Medical problems in surgery for pulmonic stenosis

Medical Problems in Surgery for Pulmonic Stenosis

By ROBERTF.

ZIECLERAND THOMAS GAHAGAN

HE FIRST MEDICAL PROBLEM in the surgery of pulmonic stenosis is accurate diagnosis which must include both a qualitative determination of the various forms and combinations in which this lesion occurs and either a direct or inferential measure of its quantitative magnitude. In view of the specq_fic choice of an appropriate surgical procedure, the anatomic situations in which pulmonic stenosis or atresia may occur, either alone or in combination with other significant malformations, have been classified as follows: A. Uncomplicated valvular pulmonic stenosis with closed interventricular septum. (1) Closed interatrial septum, or valve-competent patent foramen ovale; (2) with associated interatrial septal defect, and either no shunt in either direction or left-to-right atrial shunt; and (3) combined pulmonary and aortic stenosis. B. Severe pulmonic stenosis, or atresia, with closed interventricular septum, and right-to-left atrial shunting (normal, valve-competent, patent foramen ovale or abnormal interatrial septal defect). (1) With tricuspid stenosis and underdeveloped right ventricle; and (2) with well-developed right ventricle and pulmonary artery. C. Pulmonic stenosis, either valvular or subvalvular, or combined, with interventricular septal defect, and well-developed pulmonary artery. (1) With normal root position of great vessels and left-to-right shunt; (2) infundibular pulmonic stenosis with small interventricular septal defect, and no significant shunt in either direction; and (3) with either normal root position of great vessels or variable degree of aortic dextroposition, and right-to-left intracardiac shunting. D. Severe pulmonie stenosis or atresia, with hypoplasia of pulmonary artery and its branches, interventricular septal defect, and obligatory total, or near total, right-to-left intracardiac shunting, regardless of great vessel root positions. (1) With compensating patent ductus arteriosus; and (2) with bronchial artery collateral circulation only.

T

SOME NOTES ON DInCNOSIS It is not the purpose of this paper to include a detailed discussion of differential diagnosis, as important as this aspect of the subject is. Suffice it to say that an accurate preoperative diagnosis can and must be made, utilizing physiologic as well as anatomic information which is available both directly and inferentially through clinical history and physical examination, conventional radiography, electrocardiography, cardiac catheterization, and selective cineangiocardiography. Perhaps particular emphasis, however, should be placed upon the importance and the technical feasibility of establishing a definitive diagnosis as early as the problem may arise, even, or perhaps most particularly, in early infancy. This, of course, implies the occasional urgent 15 Paoc~Ess IN CAXaDIOVASCVLAa DISEASES,VOL. 8, No. 1 (JuLy), 1965

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importance, and again the technical feasibility, of surgical correction or palliation at any time including early infancy. Even without the immediate need for early surgery, a detailed diagnostic evaluation would seem under all circumstances to offer the best basis for medical management and perhaps later surgical planning. Mention must also be made of the diagnostic need for recognizing, or at least suspecting, the presence of pulmonic stenosis as an accompaniment, never entirely unimportant and sometimes even critical, of some other apparently more dominant defect. In such a situation it may occur in either of two forms: (1) As the primary maK(rrmation for which a patent ductus arteriosus, tor example, may actually be an important compensatory mechanism but at the same time dominate the clinical picture in terms of a "typical" murmur and absence of cyanosis; and (2) as an associated but potentially significant "complication" of a major left-to-right shunt, atrial or ventricular, and involving the differentiation between actual pulmonie stenosis and a relative right ventricular outflow obstruction due to increased stroke volume and ejection pressure. In either situation no proper or adequate surgical decision can be made without first an accurate medical evaluation. SURGICAL INDICATIONS

The next sequential consideration, having established a definitive quantitative as well as qualitative diagnosis, is that of proper indications for corrective or palliative surgery. These will, of course, vary according to the specific diagnostic entity in question, according to the factor of age, and perhaps other individual factors to be enumerated separately. Simple, uncomplicated valvular pulmonic stenosis, with closed interventricufar septurn and essentially closed interatrial septum (i.e., nothing more than a valve-competent, patent foramen ovale). Ordinarily the usual, or at least the single most important, indication for surgical correction of simple pulmonic ,valve stenosis (pulmonary valvotomy, either by the "closed" Brock, transventricular technic or by the direct vision, transarterial technic with caval, inflow occlusion) is the quantitative degree of severity; and in this regard there may well be valid room for certain variations of individual opinion, and consequently no necessarily absolute criteria, particularly in the range of moderate magnitudes. Nevertheless, there are some basic facts and principles which should prevail. The first is concerned with the problem of determining quantitative criteria of any kind. Assuming "normal" cardiac output, it is generally, and probably properly, considered that right ventricular pressure and pressure-work increase in more or less direct proportion to the degree of outflow obstruction. But this proportion is not necessarily best expressed in the level of just systolic right ventricular pressure (which may be in part artefactual or may represent early opening resistance rather than necessarily fixed and limited crosssectional area). Rather is it a function of the total area inscribed under the whole ventricular ejection curve or, in other words, as mean pressure considered in relation to stroke volume. This may, of course, be measured directly

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Fig. 1.--The chest x-ray of a 4 year old child with combined valvular and subvalvular pulmonic stenosis of severe degree. Right ventrieular pressure measured 180/6 mm, Hg (mean 90) on cardiac catheterization. The ventricular septum was intact, but there was right-to-left shunting through a patent foramen ovale. Of significance here is the paucity of radiographic evidence of "cardiac" enlargement (specifically right ventricular) commensurate with the physiologic severity of the defect. This is in part due to the presence of atrial decompression and in part to the basic failure of conventional radiography to detect even rather severe degrees of right ventricular "hypertrophy." Also of significance is the apparent absence of poststenotic dilatation of the pulmonary artery. by cardiac catheterization, or may be inferred with reasonable accuracy from the precordial lead electrocardiogram. The conventional radiographic appearance of the heart is very far from providing an accurate index to the amount of uncomplieated and compensated right ventricular hypertension and hypertrophy and, therefore, the quantitative severity of the pulmonic stenosis, except perhaps in rather far advanced and otherwise obvious degrees. In this latter regard, the varions evidences of marked, and unquestionably surgical, significance to the degree of right ventricular outflow obstruction include the following: (1) Obvious right atrial and right ventricular enlargement on x-ray examination, with normal pulmonary vascularity, and without cyanosis; (2) right-sided congestive heart "failure," with prominent hepatomegaly, etc.; (3) less than marked radiographic enlargement of the right side of the heart, but with decreased pulmonary vascularity, and cyanosis due to right-to-left atrial shunting; (4) electrocardiographic evidence of significantly quantitative right ventricular hypertrophy (hypertensive), with or without dilatation; and (5) direct physiologic a n d cineangiocardiographic evidence of moderately severe, or severe right ventricular outflow obstruction (in this case valvular). Another principle of concern is that of the importance

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Fig. 2.--Chest x-ray of a 3 and 5 year old child (A and B, respectively), each with severe valvular pulmonic stenosls with closed septa. In B typical poststenotic dilatation of the pulmonary artery is well in evidence; in A this is also present but obscured radiographically by the massive right-sided cardiac enlargement. Pulmonary vascularity in both instances is apparently decreased. of age. In contrast to the situation of a septal defect in which progressive improvement with age may be expected, at least under certain critical volumetric circumstances, pulmonary (or aortic) obstructive defects frequently become increasingly severe because of less than proportionate growth of the cross-sectional vah, e area with respect to the physiologic requirement of increasing stroke volume. Particularly above a certain critical level of quantitative severity, a given degree of pulmonie stenosis in infancy may be expected to reach a level of surgical importance within a reasonably predictable period of time. Below this critical level increasing severity is, on the contrary, unanticipated, just what this critical level is in actual measurement is difficult to define; perhaps the more important thing is that for each infant individually any progressive changes in quantitative severity can be determined inferentially and with reasonable accuracy from electrocardiographic patterns and without necessarily the need for repeated cardiac catheterizations. Furthermore, with relatively severe valvular pulmonary stenosis, again especially irt infancy, there is a considerable likelihood (and danger) of the development of a secondary and also increasingly severe subvalvular obstruction due to right ventricular outflow tract, muscular hypertrophy. The visual appearance on selective cineangiocardiography of significant hypercontractility of the right ventricular, subvalvular, outflow tract may serve as a valuable guido to the probable occurrence, or not, of this structural complication. Even without direct surgical correction, however, the latter may retrogress spontaneously and probably completely providing a thoroughly successful valvotomy is done sufficiently early. Still another diagnostic help toward deciding the time and type of operative procedure is the presence or absence of poststenotic pulmonary artery dilatation. With such dilatation a transarterial valvotomy with caval occlusion, with

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:IVIEDICAL P R O B L E M S I N PUL1V~ONIC STENOSIS

Palm. Stenosis, Closed Sepia I 2 5 aVR aVL

5yrs. aVF

VI

Vs

V2

V3

V4

V5

V /- s

Fig. 3.--Typical electrocardiographic pattern of a marked degree of combined right atrial and right ventricular enlargement ~s observed in severe right ventricular outflow obstruction. This is the electrocardiogram from the same patient whose chest x-ray is shown in figure 2-A. or without hypothermia, is feasible, probably at almost any age. Without such dilatation the surgical choice might otherwise be in favor either of a transventricular (Brock) type of palliative procedure, especially in infants, or an open type of corrective procedure with the pump-oxygenator in older children and adults. The presence of a complicating interatrial septal defect, if such can actually be demonstrated, also serves as an indication for cardiac bypass (or possibly the choice of deeper hypothermia) in order that both defects may be corrected at the same operation. Severe pulmonary stenosis or valvular atresia, with closed interventricular septum, normal great vessel root position, and interatrial right-to-left shunt through either a patent foramen ovale or interatrial septal defect. Because of its physiologic severity, particularly with respect to systemic arterial oxygen unsaturation rather than to congestive failure, this is a situation most likely to be encountered clinically and to require definitive management in infants. Only if there is a reasonably well-developed right ventricle and pulmonary artery and, practically synonymously, an adequate and competent tricuspid valve, can a really corrective pulmonary valvotomy be performed. Other attempted procedures, both palliative and corrective, seem for the most part to be almost completely ineffective, either immediately or over even a relatively short period of time. These include systemic-pulmonary artery

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I

Tetra/ogy 2 3

aVR

/I too. aVL

aVr

1 V4R

V/

Ve

VJ

I/4

Vs

Ve

V/- e

Fig. 4.--Typical electrocardiographic pattern as observed in pulmonary stenosls with interventrieular septal defect (tetralogy). This pattern is representative of a lesser quantitative degree of right ventricular enlargement than that shown in figure 3. Even with complete pulmonary atresia, the extent os right ventricular enlargement should not be expected to increase in this situation because of the ability of the right ventricle to decompress, as it were, through either the interventricular septal defect or the arota directly. shunts, infundibular resection (with outflow tract "roofing"), and caval-pulmonary anastomosis. The principal factor in medical management is again the establishing of an accurate and anatomically detailed diagnosis. Pulmonary stenosis or atresia with interventricular septal defect, and rightto-left intracardiac shunting. A group of defects, and various combinations of defects, are comprised within this seemingly single category, some os which are amenable to complete anatomic correction and some of which can probably only be considered capable of surgical palliation by shunting procedures. Some are perhaps not operable at all. Both the anatomy of the defect and the clinical severity (hypoxia) with specific reference to age are important in determining the nature of and the optimal or necessary time for the operative procedure. In summary form, the indications for surgical palliation in the form os a systemic-pulmonary shunt may be considered to include the following: 1. Severe hypoxia in infancy, with danger of cerebral damage or death, or at best relatively severe limitation of growth and activity early in life, especially manifest in the form of spontaneous anoxic attacks with loss of consciousness. 2. Pulmonary atresia, or severe stenosis, with marked underdevelopment of the pulmonary artery and its branches, evidenced historically by the presence

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Fig. 5.--Two selective eineangiocardiograms (right ventricular) in infants with complete valvular pulmonie atresla with closed interventricular septum and normal great vessel root position. In the top figure there is a sut~ciently well developed right ventricle and outflow tract to permit successful, direct-vision pulmonary valvotomy (which was done in this case bv the transarterial route, with caval occlusion and mild hypothennia). In the lower'figure the situation seems inoperable by any current method of surgical approach. of cyanosis right from birth. Occasionally multiple, peripheral sites of pulmonary artery obstnlction, demonstrated angiocardiographically. 3. Unfavorable or uncorrectable anatomy (keeping in mind that what may be considered "uncorrectable'" at one time or by one surgeon might prove to be correctable at some other time by some other surgeon): (a) Underdeveloped right ventricle; (b) complete aortic dextroposition; (c) transposition of both great vessel roots; and (d) complicating defects of A-V valves, etc. On the contrary, favorable conditions for complete, open correction on total cardiac bypass include the following: (1) Clinical severity which will permit scheduling open surgery at an "optimal" age, perhaps 4-7 years; (2) Localized outflow tract (valvular, subvalvular, or both ) obstruction, with well-developed main pulmonary artery and branches; and (3) Correctable intracardiac anat-

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omy, including: (a) Localized interventricular septal defect; (b) little or no aortic dextroposition; and (c) absence of complicating malformations. If the absence of any pulmonary artery is suspected, but cannot be proved clinically or by direct physiologic and angiocardiographic study, either no corrective or palliative surgical procedure is indicated (because not possible) or exploratory thoracotomy may be in order for the purpose of trying to find some pulmonary artery to which a compensating systemic-pulmonary anastomosis may be made cr at least attempted. It might be noted too that even in cases in which nothing direct is accomplished surgically, the patient quite often survives and seems improved, probably by virtue of the dea, elopment of collateral channels by way of vascular adhesions across the pleural (perhaps more particularly mediastinal) surfaces. It is this fact which one time led to a trial of the poudrage technic for the artificial stimulation of additional pleural collateral channels. PR~OPEnAa-IVE MEDICAL PROST.EMS

Congestive, Mechanical, Cardiac Failure In severe right ventrieular outflow obstruction, particularly with closed septa, the right ventriele may not be able to maintain a normal minute output or stroke volume, with resulting residual diastolic volume, increased right atrial and central venous pressure, and systemic, visceral congestion (hepatomegaly, etc.). The medical management of such myocardial failure is usually not very effeetive or satisfactory, especially over any extended period of time. The only really effective form of treatment is surgical relief of the mechanical cause, in this ease pulmonie stcnosis; and the best that digitalis and diuretics can do is to prepare the patient for operation by securing whatever temporary improvement such drugs may provide. The following schedule of procedures, drugs, and approximate dosages may provide a useful guide to the medical management of congestive rightsided cardiac failure: (1) Oxygen administration by tent; (2) dietetic salt restriction (results not impressive) ; (3) digitalis, digitoxin orally, 30-35 tzg./ Kg. of body weight for initial digitalization; 0.1 of this amount for daily maintenance; (4) diuril orally, 125-250 rag. once or twice daily; and (5) Thiomerin hypodermically, 0.05-1.0 ce. These same therapeutic measures may, of course, also be applicable for congestive failure of other mechanical origins, such for example as with massive left-to-right shunting, etc. As usual for mechanical situations, however, and particularly with an otherwise normal myoeardium, digitalis and diuretics can hardly he counted on for any real, long-term help. Only surgical correction of the meehanieal malformation can do this. But digitalis particularly has some other exceedingly important uses in situations complicating pulmonary stenosis, namely the control of paroxysmal taehyeardia and proteetion against hypoxic cardiae depression with bradycardia or arrest. "Anoxic" Attacks With the reduction in the volume of pulmonary blood flow and the accompanying systemic arterial oxygen unsaturation that result from pulmonie

MEDICAL

PROBLEMS

IN P U L M O N I C

STENOSIS

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stenosis and any intracardiac (apparently more particularly intraventricular) communication and right-to-left shunt, a diagnostically typical and variably severe symptomatology occurs. This includes disproportionate hyperventilation either with effort or more or less spontaneously, presumably as an attempt to correct for both lack of oxygen and accumulation of carbon dioxide. Together with this increased respiratory effort there occurs a still further reduction in systemic arterial oxygen saturation with increasing cyanosis and perhaps even loss of consciousness. With this severity of general hypoxemia the cardiac response is characteristically that of marked slowing, which may actually make the physiologic situation worse and even result in death. This cardiac depressive reaction to generalized myocardial hypoxia is in marked contrast to the effect of localized oxygen deficit resulting, for example, from segmental coronary artery obstruction, and in which there is an established boundary between normal and hypoxic myocardium. In this latter situation there is usually increased rather than decreased irritability, evidenced by ectopic loci of either frequent premature beats or even paroxysmal tachycardia (ventricular). And in this situation of myocardial depression and slowing, digitalis apparently has a distinctly beneficial and even potentially life-saving action. This drug seems to be able to prevent serious depressive slowing of the heart rate, possibly by preserving sufficiently efficient myocardial contractility as to maintain both circulation and at/east a critical minimum of blood oxygenation. Or perhaps there may be some direct influence on heart rate. In any case, with severe hypoxia, digitalis administration is an important therapeutic part of the medical management of so-called "anoxic" attacks and a part of the preoperative preparation and protection of the patient--specifically in the prevention of bradycardia and cardiac arrest during the induction of anesthesia or at any time during operation at which systemie arterial oxygen unsaturation may for any reason reach a critically low level. There are certain other, perhaps more immediate, medical measures which should be employed in the treatment of typical, or perhaps atypical, anoxic attacks. The first and probably the most important of these is the administration of morphine hypodermically in a dosage of 1 mg./10 pounds of body weight. Contrary to the rule that clinical hypoxia ordinarily contraindicates the use of morphine, in this particular situation its use seems to be specifically beneficial. Also of apparent physiologic and clinical benefit is the assumption of a knee-chest position, illustrated by the typical squatting position that characterizes dyspneic children with tetralogy or tetralogy-like cardiac malformations. In this regard it is a mistake to attempt to make an hypoxic infant lie on its back, in a physiologically disadvantageous position. It seems much better to place it face down in the knee-chest position. The administration of oxygen by mask also constitutes a fairly standard routine in the management of these hypoxic episodes. With the severity of the existing decrease, or limitation, in the possible volume of pulmonary blood flow such provision for increased environmental oxygen probably has relatively little therapeutic effect except perhaps under hyperbaric conditions. Then, again, a clinical situation this severe constitutes a valid indication for early or even

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Fig. 6A

Fig. 6B See legend on facing page.

M E D I C A L P R O B L E 3 I S I N P U L N I O N I C STENOSIS

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Fig. 6C Fig. 6.--Continuous blood oxygen saturation, measured by ear oximetry, during anesthesia and shunt operation (Blalock) for tetralogy of Fallot. After endotraeheal intubation (A), systemic arterial oxygen saturation began to fall progressively; pulse and blood pressure became imperceptible; by auscultation the heart rate was slow and the sounds of poor quality; the chest was not yet opened. After epinephrine (B), there was a short but unsustained rise in blood oxygenation, together with some increase in heaa-t rate but still a very poor quality peripheral pulse and nonmeasurable blood pressure. Cedilanid was then given intravenously and was followed by a prompt, increasing, and sustained rise in blood oxygen saturation and a visually improved heart action, now obsel~able direetlv following thoracotomv. This degree of improvement was maintained throughout t~he remainder of the shnnt operation (C). That this improvement following the administration of digitalis was a bonifide therapeutic response and not just some simple coincidence has been "proved" by repetition under similar circumstances mauv times, so regularly in fact that such has become the expected pattern, and anoxic cardiac depression a primary indication for the administration of digitalis, either prophylactically or therapeutically. emergency surgery; since such is more frequent in infancy, the operation indicated is usually a systemic-pulmonary anastomosis (Blalock or Potts).

Disturbances of Cardiac Rate and Rhythm Paroxysmal tachycardia, usually supraventricular, is not a common, spontaneous preoperative accompaniment or complication of puhnonic stenosis, although when it does occur it may disturb an already somewhat precarious situation rather seriously. Under certain quantitatively critical circumstances at least, an already limited cardiac output may apparently be decreased further, with potentially dangerous clinical consequences. Ordinarily, full

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rapid digitalization suffices to control this situation, particularly with atrial tachycardia or flutter. However, with the increased hypoxia that may occur (due to a further decrease in volume of pulmonary blood flow and an increased right-to-left shunting at either the atrial or the ventricular level) and, even more particularly perhaps, with the fall in systemic arterial blood pressure that quite regularly cccurs, the addition of vasopressor drugs may frequently be of almost critical clinical importance. If increased hypoxia seems to be a significant factor, oxygen administration may also be of some therapeutic value. While paroxysmal tachycardia does not occur spontaneously with any great frequency, this complication may arise during diagnostic cardiac catheterization, and whenever it does it may or may not be serious depending on the quantitative severity of the heart disease in question. Bu,t another difficulty is somewhat more likely to appear here, namely the differentiation between supraventricular and ventricular tachycardia. If right bundle branch block is present in the electrocardiogram, either as a no~mal expression of the type and degree of right ventricular enlargement or as it is not infrequently induced by catheter manipulation, then this form of the ventricular deflections may simulate that of paroxysmal ventricular tachycardia which also can, and does occur with the mechanical stimulation of catheter manipulation, possibly somewhat more frequently in severe right ventricular outflow obstruction than with other lesser types of right-sided work-strain and enlargement. In either eetopic mechanism (supraventricular or ventricu!ar ) full and immediate digitalization is probably the best initial therapeutic procedure. The more important question here involves the choice of management should the arrhythmia continue apparently uncontrolled by therapeutic digitalization. A cantious use of vasopressor drugs if systemic blood pressure is low is probably not contraindicated. Qninidine would be of theoretic value in case of ventricular tachycardia but is probably too dangerous to be justified. In this particular type of situation it would probably have to be administered intravenously; and it is further said to be somewhat more hazardous in the presence than in the absence of bundle branch block. Perhaps the best recent addition to the medical management of a serious arrhythmia in this situation is external DC electric countershock which may have here one of its best indications for emergency use. Again, if the occurrence of paroxysmal tachycardia, however it may occur, does precipitate a significantly more serious clinical situation, then this too almost certainly constitutes a positive indication for early and urgent, perhaps even almost emergency, surgical intervention. The dangers associated with waiting probably outweigh any other danger of early surgery especially if this should be of a palliative type, or if corrective simple pulmonary valvotomy. The present risk of total intracardiac correction, as of both interventricular or interatrial septal defect and subvalvular or valvular pulmonic stenosis, especially in early infancy, may still be quite formidable and perhaps therefore to be postponed if possible. Complete A-V heart block is even less frequently a complication .of pulmonic stenosis, and is seldom a problem for strictly medical management in the

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specific sense of therapeutic drug administration. Of greater practical importance is its consideration for either pacemaker implantation or surgical correction or palliation or perhaps both simultaneously. Decision here is partly a matter of assessing the severity of the combined mechanical situation and partly a matter of clinical iudgment according to the specific requirements of the particular situation. Assessing the absolute importance of the pulmonary stenosis may be particularly diffcult physiologically because of the fixed limitation in cardiac rate and output, and ,because also of the "normally" increased stroke volume and ciection pressure secondary to decreased heart rate of the magnitude usually occurring in complete A-V block. Radiographic heart size too may be evaluated only with certain diffculty, again because of the "normal" increase accompanying complete block especially with a slow, fixed rate. Even the electrocardiogram (right precordial leads), from which right ventricular work can usually be inferred with reasonable accuracy, may be of limited vahie especially if the ventricles are controlled by an idioventricular focus, but also by virtue of the factor of dilatation associated with the bradycardia. Despite these various specific limitations, the combination of data available from these various studies, plus most importantly the general clinical evaluation, usually suffices for determining the surgical requirements. Other Miscellaneous Conditions

As with practically any other surgical situation at probably any age, but perhaps more critically applicable to infants, adequate preoperative, therapeutic attention must be given such problems as respiratory tract infections, both maior and minor (antibiotics, expectorants, decongestants, etc.), anemia and possibly other specific nutritional deficiencies (especially if relatively longterm consideration can be given in preparation for surgical correction), and certain other specific problems and complications. There was a time when polycythemia in cyanotic congenital heart disease (with pulmonary stenosis or atresia) was regarded as requiring specific therapeutic measures partly iust for its own sake as a physiologic abnormality and partly in the attempted prevention of secondary complications especially crf a thrombotic nature. Depending on the degree of polycythemia, attempts have been made to partially correct this situation preoperatively by variable sized venesections usually followed or accompanied by quantitative replacement with equivalent amounts of blood plasma. Whether and how useful this might be is probably open to question; and perhaps no generalized claims for or against it would be iustified. It may be something to consider in individual patients with individual and particular problems. The associated use of anticoagulants is probably not iustified. In addition to the danger of spontaneous thromboses and perhaps thromboembolic complications, polycythemia and hypoxia also appear to make possible the opposite danger, namely that of hemorrhagic complications, particularly in the event of surgery. A number of possible mechanisms may, either individually or in combination, serve to account for an abnormal bleeding tendency in cyanotic congenital heart disease, as in the present context--tetralogy of Fallot. These include: (1) Increased total blood volume; (2) mechanical

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engorgement and distention of the vascular, including capillary, bed; (3) decreased number, or qualitative alteration in platelets and platelet function; (4) mechanical interference (by increased red blood cell mass) of fibrin organization, polymerization, etc.; and (5) tile enhancing effect of hypoxia on fibrinolytic mechanisms. Opinion may be divided as to the particular or predominant mechanism for the hemorrhagic tendency in any individual case. Opinion may likewise be divided as regards specific means of medical management. Certainly there is complete agreement on the need for meticulous care in achieving complete hemostasis during operation of whatever kind. Nor is there any question concerning the need, when it arises, for postoperative surgical intervention in the event of continued intrathoracic bleeding. Other measures which may be helpful, or perhaps may not, include the preoperative reduction of total blood volume and red cell mass by venesection, the postoperative administration of vitamin K, and transfusion with fresh whole blood again postoperatively. Two specific infectious complications deserve particular mention and therapeutic, preoperative management. The first is bacterial endocarditis; the second, presumably though perhaps not necessarily infectious, is brain abscess. Bacterial endocarditis, usually subacute, is too large a subject of itself, and has been discussed sufficiently and adequately, for any great detailed consideration to be justified here. Furthermore, the chief interest here is specifically the medical problem in the perspective of surgical correction or palliation. In this regard, unless the clinical severity of the basic cardiac defect warrants emergency surgery, adequate curative treatment of the infection is imperative, either preoperatively or at any other time. Therapeutic adequacy requires the choice of the proper antibiotic with respect to the responsible organism and its specific resistance or sensitMty, the achieving of an effective (preferably baeteriocidal) antibiotic blood level, and its maintenance over a sufficiently long period of time to be curative. The occurrence in cyanotic forms of puhnonary stenosis of cerebral vascular complications including cerebral thrombosis, acute hypoxic cerebromalacia, and brain abscess, offers a somewhat different medical-surgical problem. Because of the vulnerability of the central nervous system to localized as well, of course, as generalized oxygen deficit, and in an effort to minimize vascular insufficiency in what might be considered actually or analogously a periinfarction zone, or to facilitate abscess healing either with or without, but ordinarily with, craniotomy and drainage or excision, increased systemic arterial oxygen saturation by surgical palliation (a systemic-pulmonary arterial shunt probably still preferred over attempted complete correction in this situation) should be considered as an emergency surgical indication. PREOPERATIVE ORDERS

Before proceeding to operative considerations, it might be well simply to list one set of precatheter and presurgical orders which have proved their usefulness and value over an extensive clinical experience. Again, there might well be reason for other individual preferences, especially for drug combinations; but these do seem both effective and safe.

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"Routine" precatheter orders: (1) Up to 40 pounds of body weight, morphine 1 mg./10 pounds, sodium phenobarbital 30 rag./ 10 pounds; (2) from 40--100 pounds of body weight, demerol 1 mg./pound, hypodermically, seconal approximately 1 reg./pound, orally; (3) the above sedation to be given 30-45 minutes before called for cardiac catheterization; (4) atropine may be added in a dosage of 0.05 mg./10 pounds; and (5) scconal, in addition to above, may be given as necessary, intravenously, in a dosage of from 1-2 mg./pound of body weight. "Routine" preoperative orders: In addition to routine surgical skin preparation, optional cleansing enema the night before operation, etc.: ( 1 ) Nothing to be given orally for 4-6 hours preoperatively; (2) preoperative, on-call medications, morphine 1 mg./10 pounds of body weight; atropine 0.05 rag./10 pounds of body weight; (3) blood type and cross-match, appropriate amount available in operating room; (4) prophylactic digitalization in case of severe hypoxia, 30 ~g. digitoxin/Kg, body weight, orally, 24 hours preoperatively; and (5) prophylactic antibiotics not considered routine. MEDICAL RESI'ONSIBILITY FOR SURGICAL DECISION

The primary medical responsibility preoperatively, on the particular part of the individual physician, is to establish as accurate and detailed an anatomic and physiologic diagnosis as possible. The primary responsibility of the surgeon is to fulfill his best possible effort to accomplish the con'ective or palliative goal mutually set and agreed upon by physician, surgeon, and parent or patient. Between these two separate, though obviously related, responsibilities lies a great middle-ground ef varied, sometimes simple, sometimes complex, personal and professional relationships and divisions of responsibility in translating the complete clinical diagnosis and prognostic evaluation into therapeutic terms, either medical or surgical or, frc~luently, both combined. And in this regard it is well to remember that any decision against operation is as much a positive, active decision as is that for operation, each with its own risk of both morbidity and mortality. To either of these decisions the physician brings his knowledge, not only of the anatomy and physiology of the defect or defects in question, but also of their natural history, adding thereby the dimension of future expectations to the present evaluation. The surgeon, on his part, brings a first-hand knowledge of what can be done technically and with what hazards, again both now and in the forseeable future. Together, it might be expected that as factual and accurate an approach as possible might be made to the questions of whether or not surgery, what type, and when. MEDICALPROBLEMSDURING SURGICAL CORRECTION

OR PALLIATION

While they are all rather intimately interrelated, there are probably three, ~airly distinct fields of interest in the surgical cardiac patient: (1) The surgical aspect itself, the "mechanical" correction of the defect or defects in question; (2) the anesthetic aspect, which really could be considered broadly to comprise most if not all the physiologic mechanisms, and their regulation, during the anesthetic and surgical period; and (3) the medical, cardiologic

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aspect with its primary though not necessarily exclusive focus on the functional integrity of the heart specifically and entire circulation generally. None of these particular aspects or perspectives can be completely dissociated from either of the others, while at the same time each falls within the specialized interest and responsibility of one particular member of the complete team. What are some of the cardiologic problems associated with anesthesia and operation, and the principles of their management?

Disturbances of Cardiac Rate and Rhythm One of the most frequent and probably most important is that of cardiac arrhythmias. And these may be of several different types. There are a variety of atrioventricular nodal mechanisms, both with and without dissociation, frequently irregular but characterized generally by a fast ventricular rate; these are apparently innocent, and require no particular attempt at modification or "control." It is a good general rule in this regard that fast heart rates with almost any abnormal, supraventricular mechanism arc apt to be relatively safe, whereas slow rates (of 40-45/minute or less), practically regardless of the precise electrical mechanism, must be viewed with considerable concern. Another type of cardiac arrhythmia is that, or those, due to ectopic foci of impulse formation: single or multiple, isolated or repetitive, supraventricular or ventricular. Of these the most serious are multifocal or repetitive ventricular premature systoles or persistent tachyeardia, the specific danger being that of progression to ventricular fibrillation. This type of rhythm disturbance seems somewhat more likely to occur in malformations in which there is marked left rather than right ventricular strain and enlargement (the factor, perhaps, of relative coronary artery insufflciency). Further, there used to be a fairly direct relation to specific anesthetics such as cyclopropane, an etiologic factor which is significantly reduced in the use of newer and safer anesthetic agents. In the event of such arrhythmias (multifocal ventricular premature systoles or paroxysmal ventricular tachycardia) an attempt should be made first to improve blood oxygenation; the anesthetic agent should first be discontinued and then probably changed; and particularly careful electrocardiographic monitoring should be continued for evidence pointing to the need for more definitive measures such as the use of depressant drugs (quinidine, pronestyl, etc.) or DC electric countershock, and possibly quick cannulation for extracorporeal circulatory control. The supraventricular extrasystolic arrhythmias are ordinarily not so seriously significant, and are usually brought fairly easily under pharmacologic control by immediate, full digitalization. The most serious disturbances of the cardiac mechanism during anesthesia and operation are those which are characterized by a slow ventricu]ar rate (40 per minute or less). These include sinus bradycardia, sinus arrest, slow A-V nodal rhythm with or without dissociation, complete A-V block, idioventricular rhythm, and perhaps others. Complete cardiac arrest is, of course, the terminal mechanism which seldom seems to occur suddenly and totally without some forewarning. With careful electrocardiographic monitoring, which is an absolute and unqualified operating room necessity, some ante-

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3i

eedent slowing will practically invariably be discovered. Whether this gives sufficient opportunity for effective therapy is another question, depending partly on the specific cardiac (or perhaps respiratory, including hypoxic) mechanism and partly on the type of cardiac malformation present. In any case immediate measures to improve blood oxygenation as well as the administration of appropriate drugs are of vital importance. In this group of abnormal cardiac mechanisms various drugs may be considered, either alone or in various combinations, including: (1) Digitalis in full digitalizing dosage; (2) atropine in sufficient dosage to produce complete vagal paralysis; (3) cardiac stimulants such as isuprel (isoproterenol hydrochloride), agents such as epinephrine probably to be avoided unless given extremely cautiously in very small doses. On occasion any or all these measures may prove ineffective, in which case the only possible resort must be to some form of electrical stimulation most appropriate to the particular circumstance; but even this, unfortunately, is no guarantee of final success, since the slow mechanism may represent the irreversible result of some serious metabolic deficit to the myocardium and the conduction system. Another related problem is the occurrence of complete A-V block or dissociation induced surgically during closure of in this case an associated interventricular septal defect. Here, it is important initially to differentiate between "dissociation" and "block." A-V "dissociation," ordinarily with a relatively fast ventricular rate in response to a supraventricular focus, frequently occurs transiently at almost any time during anesthesia and operation. This is usually spontaneously reversible or may be converted to normal with atropine, and is of no particular surgical concern. If, however, a slow, usually though perhaps not necessarily idioventricular, heart rate occurs during the closure of an interventricular septal defect, possibly even with the placement of a single particular suture, then A-V "block" exists, along with the questions of whether or not it will be reversible and how best to manage the now complicated situation. Several medical measures may be employed in an attempt either to convert the an~hythmia or at least to maintain a relatively fast and efficient ventricular mechanism which will promote survival and pro~ide the opportunity for late spontaneous recovery to normal sinus mechanism. These include: (1) Isuprel intravenonsly and later sublingually; (2) atropine in vagal paralyzing doses; (3) ccrrection of existing acidosis with sodium bicarbonate or lactate Ringer's solution. Even if the ventricular rate remains fairly fast, though still with blocked A-V conduction, the decision must be made as to pacemaker implantation. A permanent internal pacemaker may be implanted in order to avoid a future, second thoracotomy; or, more frequently, electrode wires may be implanted for necessary use with an external pacemaker unit, particularly during the immediate postoperative period. Although late "spontaneous" reversions to normal sinus mechanism have been reported, the likelihood of such occurring decreases rather markedly after the first few days to a week postoperatively. For this reason, plus the inherent dangers associated with persistent block (decreased mechanical cardiac efficiency, congestive failure, and even sudden death), a postoperative patient with per-

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sistent complete A-V block should probably not be discharged from the hospital without the implantation of a permanent internal pacemaker.

Provision for Adequate Blood Replacement a~wlPerfu~ion These are important requirements, obviously, in all types of surgery, cardiovascular and others, but have particular implications, principally in the use of the extracorporeal circulation during which time the patient's entire circulation is completely dependent on the artificial meohanism, blood losses are likely to be both large and somewhat difficult to quantitate with real accuracy, and total blood volume replacement by continuous turnover a problem for equally continuous, careful and critical clinical evaluation. A great deal can be learned by observant attention to the color of the tissues, the appearance (pallor or congestion) of the oral and conjunctival mucous membranes, the state of the pupils, any changes or not in a continuously recorded electroencephalogram, the direction and magnitude of changes in various physiologic measurements which are being constantly monitored, including both arterial and venous pressures, and perhaps others. All of these signs are important both during operation and postoperatively as an indication for approaching a final satisfactory blood volume. Adequate perfusion is primarily a surgical team responsibility, but it has many important medical implications, especially in the prevention of significant and potentially serious postoperative complications, both general and local. One of the important general complications of inadequate perfusion is acidosis, the best treatment for which is obviously prevention. Local complications may result from inadequacies of either arterial perfusion or venous decompression, which too can and must be avoided by careful observation and flow adjustments. General perfusion rates and oxygen proportions have been fairly well established for various conditions and particular purposes (as, for example, with or without hypothermia), and in this ease for a bubble-type oxygenator. Adequate perfusion is considered to be provided at low, middle, and high flow rates, respectively, of 50, 75, and 100 ee./Kg, of body weight, the principle factor determining, or permitting, variability being that of temperature. Adequate blood oxygenation is achieved by oxygen flow rates of 2-3 L./minute for each liter of blood flow. There must be many problems arising in the course of surgery for pulmonie stenosis in one of its several forms and requiring some kind of medical decision and management. Little has been said, for example, regarding hypothermia which eertairdy poses any number of special and important problems, but the use of which is still, and probably will continue to be, somewhat restricted. MEDICAL PROBLEMS IN ]'FIE POSTOPERATIVE PERIOD

Medical problems presented in the immediate postoperative period may vary greatly depending upon the nature of the operation performed and upon the basic clinical (including age factor), anatomic and hemodynamic situation. There are also certain problems which may very well occur in eom-

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men to the entire group. For purposes of this discussion the types of surgical procedures might conveniently be d M d e d into: (1) Simple, direct pulmonary valv.otomy (either the Brock, transventricular procedure or, more commonly, direct vision, transarterial valvotomy with caval occlusion and with or without mild hypothermia) ; (2) systemic-pulmonary shunt (Blalock or Potts type of aortic-pulmonary anastomosis) ; and (3) complete, open correction using the pump-oxygenator for total cardiac bypass.

Simple PulmonaryValvotomy This can be, and usually is, one of the technically easiest and least traumatic of the available operative procedures for pulmonary stenosis as represented in this group of simple or complex malformations. Ordinarily, essentially complete correction of what may be a severe hemodynamic derangement can be accomplished in but 1 to 2 minutes of caval, inflow occlusion time, with only mild protective hypothermia, with little if any significant blood loss, and practically without even touching the heart itself. This means, of course, that postoperative problems related to blood replacement, management of cardiac arrhythmias, and even to some extent pulmonary complications, are minimized, and postoperative convalescence is usually quite uncomplicated. Sinus tachycardia is not infrequently an early postoperative occurrence (scarcely a "complication"). This does not appear to be related to blood loss or to hypotension, so that blood replacement should not be predicated on the basis of this sign. Neither is digitalis indicated, nor effective, in this practically "normal" situation. Presumably this represents some transient phase of eardiocirculatory adjustment, the proper management for which seems simply to be watchful observation. Since even the immediate postoperative period following simple pulmonary valvotomy is usually quite uncomplicated, it seems scarcely justified to list and discuss all the possible complications, the most important of which will be included in the medical management of the other basically more complicated surgical situations. The basic medical problems, similar in each of the surgical procedures, involve the careful observation of "vital" signs, maintenance of fluid balance, active attention to the problem of promoting good pulmonary function, the control of pain and restlessness, and determination of the pattern of ambulation and activity. In respect of these purposes, postoperative care may be reasonably well guided by the following "routine" orders: 1. The recording of pulse, respirations, and (if feasible) blood pressure every 15 minutes until stabilized postoperatively (approximately 3 hours), then every 30 minutes for another 3 hours, then every 1 hour for approximately 6 hours ff stable. 2. Continuous electrocardiographic bedside monitoring in the event of any operative or immediately postoperative arrhythmia, conduction defect, etc. 3. Continuous humidified oxygen administration by tent for at least the first 12-24 hours postoperatively. Try out and discontinue as tolerated after this time. 4. Intravenous fluids (such as 5 per cent glucose in N/4 saline), and nothing taken orally, for approximately the first 6-12 hours postoperatively; oral fluids ad lib, and diet

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as tolerated, in 12-24 hours, first decreasing and later discontinuing intravenous fluids as oral intake becomes adequate; 5. Antibiotics--oral penicillin (q.i.d.) and intramuscular streptomycin (b.i.d.) in dosages appropriate for age and size. Discontinue streptomycin after 3-5 days if "normal" postoperative temperature elevation decreasing, and no evidence of respiratory or other infectious complications; continue oral penicillin for 1 week postoperatively or until temperature completely normal. Substitute broad-spectrum antibiotics ff hypersensitivity to penicillin. 6. Encourage patient to move frequently, sit up, and cough (aided if necessary by fairly firm manual support of the chest in order to decrease discomfort); nasopharyngea] suction as necessary to renrove secretions or, incidentally, to stimulate effective, deep coughing. Expectorants may be useful for liquefying respiratory tract secretions and prorooting their easier removal. 7. If significant pain, and particularly if respiratory tract is relatively clear, narcotics are probably not contraindicated, and are usually only necessary during the first 24--48 hours postoperatively, particularly in infants and children. These may be administered hypodermically in the following dosages: Morphine, 1 rag./10 lb. of body weight; Codeine, 2 rag./10 lb.; Demerol, 1 reg./lb. 8. Acetylsalicylic acid (aspirin) by mouth, as necessary for minor aches and pains or for reduction of high fever. Aminopyrine (pyramidon) may be used cautiously for the reduction of fever which is resistant to other usual measures. 9. Small starting, or cleansing, enema if abdominal distention or faihrre to move bowels for 2--3 days. Oral preparations such as milk of magnesia, oil and agar, stool softeners, etc., as indicated. 10. Permit activity in bed as desired and tolerated. Children and adults may be permitted and encouraged to sit up in 3-5 days, and to walk in 7 days. 11. Stitches out on seventh or eighth postoperative day. Increase degree of ambulation and activity. 12. Discharge home 11-14 days postoperatively. After simple p u l m o n a r y valvotomy, postoperative convalescence, especially in children, is ordinarily rapid and uncomplicated. Resumption of normal, essentially unlimited, activity, attendance at school, etc., m a y b e permitted usually within a period of 3-4 weeks after operation. Late complications of practically any kind are quite unanticipated, particularly with the transarterial procedm-e. After a Brock type of transventricular operation frequent ventricular p r e m a t u r e systoles have occurred, but only rarely to a really troublesome extent; the most common problems after this type of surgical correction (or more often, palliation) h a v e been either inadequate valve opening or complicating valve incompetence, either of which may or m a y not pose the question of future re-operation. Unless an otherwise successful, direct-vision valvotomy is complicated b y hypoplasia of the valve ring, subvalvular muscular obstruction, or other associated or perhaps unrelated and complicating abnormalities, any further problems requiring special medical m a n a g e m e n t are virtually at an end. Antibiotic prophylaxis against potential bacterial endocarditis, important before operation, m a y b e continued postoperatively although the question of its necessity is hardly a settled one.

Systemic-Pulmonary Shunt The creation of a Blalock or Potts type of systemic-pulmonary artery anastomosis, or artificial patent ductus arteriosus, is again, strictly speaking,

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35

an extracardiac or vascular operation, thereby more or less automatically eliminating or at least minimizing some of the postoperative problems of intracardiac surgical procedures. Further, with a mechanically successful shunt and immediate improvement in systemic arterial oxygenation, postoperative problems of practically any type, but particularly of a cardiovascular variety, are rather effectively minimized. Perhaps the most important medical measures should be directed toward the prevention of respiratory complications and tile avoidance of any situation that might lead to thrombotic occlusion of the arterial anastomosis (such, for example, as circulatory stasis, hypotension, dehydration, etc.). Among the intrathoracic complications which are somewhat more likely to occur here as compared with simple puhnonary valvotomy are phrenic nerve paralysis (usually asymptomatic, but important in the differential diagnosis of pleural fluid, atelectasis, etc.), pleural effusion or hemothorax, occasionally chylothorax, pulmonary atelectasis and possible pneumonia. Whenever thorac~tomy is accompanied by positive pressure expansion of the lung, another complication or complications may occur, namely puhnonary interstitial emphysema which may manifest itself most safely in the form of subcutaneous emphysema and more symptomatically in the forms of either pncumothorax or pneumopericardium. Somewhat more common in infants, or after long periods of intratracheal anaesthesia, is the potentially serious complication of upper respiratory obstruction due to laryngeal edema. The important thing in all of these situations is, of course, early recognition of the existing problem together with prompt and appropriately effective management. The combination of physical and x-ray examination usually suffices to make a working diagnosis; the conservative management of intrapleural complications consists of simple thoracentesis or water-seal venting of extrapulmonary air. Indications for thoracotomy and tracheostomy will be considered separately. Another extremely important problem in the immediate postoperative management of cyanotic patients, particularly though not exclusively infants, who have had palliative surgery, is the recognition of the need for operative revision of the anastomosis, e.g., evidence of early postoperative occlusion of the anastomotic site. This may be a matter of some clinical difficulty, since the continuous murmur of an artificially constructed, compensatory "ductus" is not always easily audible in the immediate postoperative period and, too, since significant cyanosis may persist either because of unrelieved polycythemia or because of respiratory complications making ventilation ineffective or pulmonary blood oxygenation inadequate. Complete functional closure of the anastomosis in the early postoperative period usually renders the patient severly hypoxic, frequently even worse than preoperatively because of the unavoidable surgical interruption of collateral vessels during pleuro-mediastinal dissection. This hypoxia is most apt to be evidenced by hyperpnea of a severity entirely disproportionate to any respiratory cause which may (or more frequently may not) be demonstrated on physical or radiographic examination. Early, emergency re-operation may as a consequence become an urgent, life-saving effort, and the early recognition of its need a combined medical-surgical responsibility.

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Another unusual, early postoperative complication of shunt surgery, especially in infants or young children, and almost exclusively with the Potts t y p e of side-to-side aortic-pulmonary anastomosis, is pulmonary congestion resulting from an excessively large shunt volume. Here again early recognition is necessary because of the potential urgency for prompt, strenuous methods of management. Immediate full digitalization plus the use of parenteral diuretics, and, of course, oxygen administration possibly under positive pressure, may stabilize the situation medically. If it does not, then again emergency re-operation in an attempt to decrease the size of the anastomosis may be indicated. In general, the same "routine" medical orders that were listed for the postoperative care of patients undergoing simple pulmonary valvotomy are equally applicable after a palliative shunting procedure. Ordinarily convalescence in this latter situation too is rapid and uncomplicated. Late complications, however, are by the nature of the situation more frequent and also more serious. These may be of two general types: infectious or mechanical. The infectious complications include subacute bacterial endocarditis and brain abscess, some of the principles and practices for the treatment of which have already been discussed. The mechanical complications are either progressively increasing inadequacy of the compensating aortic-pulmonary shunt or increasing pulmonary hypertension and left-sided cardiac enlargement due to an excessive volume of left-to-right great vessel shunting. In either of these two mechanical situations both physiologic and anatomic evaluation are necessary for the determination of not only the clinical need but perhaps more importantly the potentiality for completely corrective, "open" surgery utilizing the pump-oxygenator for total cardiac bypass.

Complete, Open Intracardiac Correction, with Total Cardiac Bypass The amount and nature of surgery to the heart, as well as the various physiologic effects involved in the use of the pump-oxygenator and cardiac bypass, make possible (though they by no means necessi,tate) a variety of potential postoperative complications which may not be quite so likely to occur in the other "simpler" forms of surgery for pulmonic stenosis. The intracardiac repair itself, i.e., closure of the interventricular septal defect, may be productive of complete atrioventricular block, an extremely important problem for further medical-surgical management. An improperly placed right ventricular incision may result in localized coronary artery insufficiency. Overzealous excision of the right ventricular outflow tract may be productive of a ventricular aneurysm, or possibly tricuspid valve insufficiency; while inadequate excision leaves a variable degree of residual outflow obstruction. Rarely, and possibly related to the critically located formation of scar tissue in the right ventricle, persistently recurrent paroxysmal ventricular tachycardia may pose a real and disturbing therapeutic problem. The use of the pumpoxygenator, particularly some of the mechanical and other associated factors in its use (such, for example, as blood anticoagulation), also given potential origin to certain more or less specific complications, including: postoperative

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37

bleeding, microembolism, cerebral edema, hemoglobinuria and renal shutdown, pulmonary atelectasis (problem of depletion of pulmonary surfactant), hemorrhagic pulmonary congestion, and others. The incidence, and consequently the danger, of many of these potential complications have been materially diminished through improvements both in pump-oxygenator equipment and in surgical and bypass technics, which really emphasizes the fact that prevention has been, and still remains, the most important aspect of management, either medical or surgical. This is most particularly true with those types of postoperative complications that seem practically completely irreversible once they have occurred. The syndrome associated with hemorrhagic pulmonary congestion and consolidation, ~or example, would appear to be fatally irreversible, apparently refractory to any and all forms of attempted medical management, but probably preventable by proper decompression of the left side of the heart during bypass and correction. Complete atrioventricular heart block too is in most cases irreversible, though not fatally so since it can be modified favorably by artificial means. Another largely preventable complication which, if not actually irreversible, may at least be uncomfortably resistant even to intensive medical management, is that of excessive hemoglobinemia and its resulting renal shutdown. A variable amount of red blood cell destruction with increased plasma hemoglobin levels is an accompaniment, and associated danger, of the mechanics of practically any type of extracorporeal circulation. And, representing primarily, a mechanical problem regarding its inception and quantitative magnitude, all mechanical means possible must be directed toward its elimination or minimization. With regard to the individual patient in whom high plasma hemoglobin levels are present following pump-surgery, medical management must be directed toward the protection and enhancement of renal function, the main clinical danger probably being renal shut-down. Probably the most pertinent principles here are to promote a high urinary output together with maintenance of adequate but not excessive hydration. In this regard, it has been found that the intravenous use of mannitol as a glomerular filtered osmotic diuretic, either during surgery routinely or immediately postoperatively i n selected cases (long pump-time, high hemoglobin level in pump blood at the conclusion of operation, sluggish kidney function in early postoperative period, etc.), is an effective and apparently safe means of producing good urinary output--providing, of course, that there is adequate circulating blood volume available to the kidneys and sufficiently effective myocardium and peripheral vascular reactivity for the maintenance of necessary cardiac output and renal filtration pressure. Myocardial function may be maintained; on proper indication, by therapeutic digitalization; circulating blocd volume can similarly be regulated by adequate whole blood replacement and the administration of intravenous fluids as indicated by the individual situation (hourly volume of urinary output collected via an indwelling catheter, etc.), using preferably 5 per cent glucose in N/4 saline. Particularly in the event of significantly diminished renal function, it may be very important

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to avoid excesses of sodium, potassium, and protein or protein catabolites at least until function recovery has progressed to a safe level. Overhydration, particularly in the presence of some significant degree of renal failure, or in the now rare situation of central nervous system microembolism (oxygen bubbles, antifoam, etc. ) may lead rather rapidly to another potentially serious postoperative complication, namely cerebral edema. Again, this is, now at least, largely preventable, but once having occurred it may or may not be reversible. Actually this has constituted a postoperative situation which, with intensive medical management, has frequently terminated in dramatic and perhaps surprizing recovery. The clinical manifestations of acute postoperative cerebral edema are variable and frequently severe--with increased irritability going on perhaps to disorientation, delerium, and convulsive seizures, decreased irritability to the point of deep coma, multiple and usually migratory changes in reflexes, neuromuscular paresis and paralysis. Perhaps the extensive involvement and the variability of the neurologic picture help as much as anything to establish the clinical diagnosis and to point the way to the necessary, practically emergency, treatment. The aim of treatment must be that of as prompt as possible reduction of cerebral edema by promoting diuresis and dehydration. This regimen can be initiated by fluid restriction, both oral and parenteral, supplying only enough to permit adequate renal function. But this may not be suffcient for the needs of the particular central nervous system problem. Diuretics may also be necessary. Inta'avenous urea has been used for this purpose; mannitol is also useful here, as is 50 per cent glucose given intravenously together with a small amount of aminophyllin (such, for example as 20--25 cc. of 50 per cent glucose plus lIX~--150 rag. of aminophyllin). The patient's as well as the pump blood must be rendered incoagulable with heparin (1.5 mg./Kg, of body weight) for cardiac bypass. Following surgical correction this heparinization must be neutralized by the intravenous administration of protamine (in the usual dosage of 3 mg./Kg, of body weight) or Other heparin antagonist. Even with this, and despite apparently good and adequate mechanical hemostasis, there may still be residual abnormalities of the clotting mechanism, induced somehow by the use of ,the pumpoxygenator, and productive of an important postoperative hemorrhagic diathesis. Any kind of complete analysis, or perhaps even some reasonably satisfactory though still approximate working evaluation of the hematologic mechanism or mechanisms involved, is usually quite impracticable because of the necessary time required for their performance. The answer just could not be made available at the critical time of its therapeutic need. As in the case of postoperative hemorrhage in polycythemia and hypoxia, a few simple bedside determinations may suffice for a gross approximation to the problem and its medical management. But in general tile same more or less "shot-gun" type of therapeutic approach is going to be employed anyway, and in most instances will be likely to succeed in controlling the postoperative bleeding. If, for example, the bleeding and clotting times are still prolonged even after the calculated neutralization of heparin by protamine, an additional amount of

MEDICAL PROBLEMS IN PULMONIC STENOSIS

,~

the latter may be indicated. If bleeding continues despite normal clotting time, attention must be directed to the rate and amount of clot lysis as a testtube determinaion. If this is abnormal, a more or less specific antagonist to the fibrinolytic mechanism may be available in episolon amino-caproic acid given in appropriate dosage intravenously. In the event of any other less easily defined deficiencies in the clotting mechanism, therapeutic replacement may be effected by the administration of whole fresh blood Instead of assuming that there is no possible localized surgical reason for continued intrathoracic postoperative bleeding, a possible decision for reopening the thorax should be considered carefully for the express purpose of locating any bleeding points or areas and providing better mechanical hemostasis. Continued intrathoracic bleeding, of obvious therapeutic importance, may be characterized by a varying combination of manifestations including actual measured blood loss (chest tube drainage), progressive respiratory insufficiency, and decreasing cardiac output. A triad of cardiocirculatory and pulmonary signs should first serve to point diagnostic suspicion in this direction. These include: (1) Increasing pulse rate; (2) increasing respiratory rate; and (3) falling blood pressure. In addition there may be pallor or cyanosis, restlessness, sweating, central nervous system depression, diminishing urinary output, acidosis, and, of course, localized physical signs of intrapleural fluid accumulation (impaired resonance to percussion, diminished breath sounds, possibly distant bronchial breathing, etc.). X-ray evidence is, of course, confirmatory of the presence, and thoracentesis will disclose the type and volume of fluid. One might expect that chest drainage should both reveal the occurrence of persistent intrapleural bleeding and keep the hemithorax clear of accumulated blood. Such is frequently not the case, however, due to the formation of clots which may effectively prevent drainage and thereby mask, at least for a time, the underlying bleeding. Failure to aspirate blood by direct, even multiple, thoracentesis may have exactly the same significance and, notably therefore, not contraindicate thoracotomy for the relief of continued intrathoracic bleeding. The clinical evidence of hemothorax is usually not particularly difficult. Nor should evidence be wanting for the detection of continued bleeding. The principal question perhaps is that of when to return the patient to the operating room for repeat thoractomy and more complete surgical hemostasis. And, again as in the case of other potentially surgical complications (such, for example, as laryngeal obstruction and tracheostomy) it is almost certainly wiser to intervene early rather than late and for precisely the same reasons. Postoperative bleeding may also occur intrapericardially and, together with clot formation preventing adequate (or perhaps any) drainage, result in cardiac tamponade. Clinically this situation is likely to be evidenced in more or less the usual way, that is, by simultaneous signs of both decreased cardiac output (falling blood pressure, increasing heart rate, etc.) and increasing systemic venous congestion (hepatomegaly, increased central venous pressure, etc. ). And again the chest x-ray should be helpful in displaying moderate but usually not marked "cardiac" enlargement, decreased amplitude of pulsations

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fluoroscopically, with or without associated hemothorax, and, importantly, clinical judgment favoring the absence of myocardial failure. Needle aspiration is scarcely necessary to make a clinical diagnosis of hemopericardium, and could even be misleading due to the presence of clots and the resulting failure to aspirate blood. Usual clinical evidences of cardiac tamponade should be sufficient to indicate the need for thoracotomy and correction of the underlying situation. Another emergency surgical procedure which may become necessary in the immediate postoperative period is that of tracheostomy, with or without mechanical ventilatory assistance, for one of two principal indications: (1) The relief of high respiratory obstruction, usually in the form of acute laryngeal edema; and (2) the more effective removal of lower respiratory, obstructive secretions. The clinical recognition of laryngeal obstruction (usually due to edema if early postoperative) is usually not difficult, characterized overtly as it is by stertorous, croupy breathing together with inspiratory retraction (suprasternal, intercostal, etc.). The difficulty, if there is any, is in deciding how long to continue conservative medical management (expectorants, high humidity, cortocosteroids, etc.) or when to provide an artificial and adequate airway by way of tracheostomy. The usual mistake in clinical judgment is to defer operative intervention too long, for example, until the patient has become exhausted, perhaps seriously hypoxic and acidotic, and liable to sudden terminal collapse, making tracheostomy a truly emergency affair, perhaps to be performed by untrained personnel under adverse physical conditions (e.g., in bed during the middle of the night), and therefore at unnecessarily great risk. It would be much better to perform this procedure simply and safely, electively with the patient still in reasonably good physical condition and with the benefit of skillful surgical performance under ideal operating room facilities. It is probably a good general rule that with any progressive severity of upper respiratory obstruction in the early postoperative period, tracheostomy is going to be necessary and therefore, had, better be performed early. There is another set of indications for tracheostomy postoperatively, more particularly though not entirely exclusively after pump-surgery, namely the syndrome associated with inadequate removal (either spontaneously and naturally or artificially by externally applied suction) of lower respiratory tract secretions. This is characterized by some combination of the following: 1. Clinical hypoxia, usually with some, though perhaps not severe, cyanosis. 2. Central nervous system depression and hyporeactivity. 3. Increased respiratory rate and effort, but decreased alveolar ventilatory exchange. 4. Acidosis. 5. Decreased cardiac output and efficiency. 6. Respiratory depression and possibly periodic apnea, with associated depressive bradycardia and terminal arrest. Again, as in the ease of upper respiratory obstruction, it is much better to introduce active, effective therapy early rather than late in this almost

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inevitably deteriorating sequence of events. And effective therapy is probably not to be achieved by usual "medical" means but rather necessitates tracheostomy as a means of providing for the removal of deep, lower respiratory tract secretions, and at the same time providing for mechanically assisted respiration. Indications for mechanically assisted respiration, particularly postoperatively, include the following: 1. Complete inability of the patient to breathe at all, loss of central nervous system control, etc., signalled by either periodic or total apnca. 2. Ability of the patient to perform the muscular act of respiration but inadequately, with inability to move sufficient air to produce sustaining alveolar ventilation and blood oxygenation---clinical and physiologie hypoventilation. 3. Ability to breathe and ventilate but only at the cost of great and fatiguing muscular effort, leading practically inevitably to final physical exhaustion and respiratory failure with all of its terminal implications. 4. Another indication, not particularly applicable in the present context, is for the purpose of employing positive pressure as in the occurrence of pulmonary edema.

Any attempt at a complete discussion of the application and use of so-called "automatic" ventilation, a combined medical-surgical responsibility, is hardly appropriate to the primary purpose of the present paper. Some summary statements, however, might be helpful. An airway must obviously be available for the application of an effective respirator system. This can be provided either by endotracheal intubation (in an unconscious patient or as an emergency, immediately postoperative procedure) or by tracheostomy (in a conscious patient and particularly when there is a reasonable expectation of his need over an extended period of time). In either case at least two primary technical requirements must be fulfilled: (1) That any leakage around the tracheal tube be prevented either by an inflatable cuff or by snug fitting of the relatively large calibre tube itself; and (2) that the length of the tube be such that its lower end rests within the trachea and not in either main bronchus. The respirator action (Bennett) may be pressure or time cycled, triggered by, and assisting the patient's own respirations in the first case, and in the second taking over automatically at an adjustable, predetermined rate. With this type of mechanical situation it is technically possible, within limits at least, to control respiratory rate and volume, the accumulation and removal of upper and lower respiratory tract secretions, the oxygen content and humidification of inspired air, the administration of therapeutic aerosols, etc. It remains during the time of such therapy to provide for fluid and nutritional requirements by way of intravenous or nasogastric feedings, or both. Late cardiac complications of complete correction, providing that correction is really "complete" and not just partial or itself complicated, should be virtually nonexistent. There is, however, a group of clinical "diseases" of perhaps a bothersome yet usually benign type which may complicate convalescence some 3-8 weeks or so postoperatively. These are probably somowhat heterogeneous in origin, representing perhaps some hypersensitivity state or perhaps a virus or "viral-like" infectious syndrome, or occasionally, par-

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ticularly in the earlier postoperative period, actually b e i n g a fibrinous, granulo, matous, and h e m o r r h a g i c pericarditis. T h e clinical manifestations of these p o s t p e r i c a r d i o t o m y or postpcrfusion syndromes are variable, including fever, malaise, chest pain, pericarditis, plenritis with effusion, splcnomegaly, lymphocytosis, eosinophilia, a n d p e r h a p s others. T r e a t m e n t is conservative, sometimes m e r e l y symptomatic, occasionally requiring the administration of corticosteroids to w h i c h the t h e r a p e u t i c response is f r e q u e n t l y dramatic. I n a n y case r e c o v e r y w i t h o u t complications is to be anticipated. REFERENCES

1. Avery, M. E., and Clcments, J. A.: Pulmonary surfactant and atelectasis. Physiol. for Physicians. 1: No. 3, 1963. 2. Blalock, A., and Taussig, H. B.: The surgical treatment of malformati,~ns of the heart in which there is pulmonary stenosis or atresia. J. A. M. A. 128:189, 1945. 3. Brock, R. C.: Pulmonary valvotomy for the relief of congenital stcnosis. Brit. Med. J. 1:1121, 1948. 4 . - - , and Campbell, M.: Infundibnlar resection or dilatation for infundibular stensois. Brit. Heart J. 12:403, 1950. 5. Deterling, R. A., Jr.: Clinical studies on open-heart surgery and cardiac bypass. In Luisada, A. A. (Ed.). Cardiology, vol. 3. New York, McGrawtlill Book Co., 1962. pp. 185--235. 6. Deysine, M., and Cliffton, E. E.: Mechanism of action of epsilon aminocaproic acid in the control of hemorrhage. In Gollub, S., and Ulin, A. W.: Bleeding in the surgical patient. Ann. N. Y. Acad. Sci. 115:291-297, 1964. 7. Gilbert, J. W., Morrow, A. G., and Talbert, J. L.: The surgical significance of hypertrophic infundibular obstruction accompanying valvular pulmonie stenosis. J. Thnrac. & Cardiovasc. Surg. 46:457, 1963. 8. Gollub, S.: Unexplained bleeding in cardiothoracic operations. In Golub, S., and Ulin, A. W.: Bleeding in the surgical patient. Ann. N. Y. Acad. Sci. 115:199-224, 1964. 9. - - : Some variables affecting hemostatsis in cardiopulmonary bypass. In Gollub, S., and Ulin, A. W.: Bleeding in the surgical patient. A~l!a. N. Y, Acad,

Sci. 115:278-290, 1964. 10. lIolswade, G. R., Engle, M. A., Redo, S. F., Goldsmith, E. I., and Barondess, J. A.: Development of viral diseases and a viral-like syndrome after extracorporeal circulation. Circulation 27: 812, 1963. 11. Jackson, I). P.: Hemorrhagic diathesis in patients with cyanotic congenital heart disease: preoperative management. In Gollub, S., and Ulin, A. W.: Bleeding in the surgical patient. Ann. N. Y. Acad. Sci. 115:235-251, 1964. 12. Karlson, K. E., and Stuckey, J. H.: Experimental studies on cardiopulmonary bypass. In Luisada, A. A. (Ed.) Cardiology, vol 3. New York, McGraw-Hill Book Co., 1962, pp. 185: 235.

13. Lam, C. R., and Taber, R. E.: Simplified technique for direct vision pulmonary vavotomy. J. Thorac. & Cardiovasc. Surg. 38:309, 1959. 14. Lewis, F. J.: Hypothermia. In Luisada, A. A. (Ed.): Cardiology, vol. 3. New York, McGraw-Hill Book Co., 1962, pp. 185-235. 15. Lillehei, C. W., Sterns, L. P., Long, D. M., and Lepcly, D., Jr.: Comparative study of polybrene and protamine for hcparin neutralization in open heart surgery. Ann. Surg. 151:11, 1960. 16. Motfitt, E. A., Kirklin, J. W., and Theye, R. A.: Physiologic studies during whole-body perfusion in tetralogy of Fallot. J. Thoracic & Cardiovasc. Surg. 44:180, 1962. i7. Mushin, W. M., Rendell-Baker, L., and. Thompson, P. W.: Automatic Ventilation of the Lungs, Springfield, Ill. r Charles C Thomas~ 1959,

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18. Potts, W. J., Smith, S., and Gibson, S.: Anastomosis of aorta to puhnonary artery. J. A. M. A. 132:627, 1946. 19. Silva-Iribarren, C. O., and Ekestrom, S.: The causes of death after openheart surgery. J. Thorac. & Cardiovasc. Surg. 47:725, 1964. 20. Smith, llomer, W.: The Kidney. Oxford, Oxford Univ. Press, 1951, pp. 791-

802. 21. Thorn, G. W.: Treatment of renal insufRciency. J. Urol. 59:119, 1948. 22. Ziegler, R. F.: The cardiac mechanism during anaesthesia and operation in patients with congenital heart disease and cyanosis. Bull. J. Hopkins I/osp. 83:9_,37, 1948.

Robert F. Ziegler, M.D., Physician-in-Charge, D~vision o[ Pediatric Cardiology, Henry Ford Hospital, Detroit, Mich. Thomas Gahagan, M.D., Associate Surgeon, Division of Thoracic Surgery, Henry Ford Hospital, Detroit, Mich.