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Obstruction to left ventricular outflow
Obstruction
to Left Ventricular
Outflow
Current Criteria for the Selection of Patients for Operation* E~JCENE BRAUNWALD, M.D. and ANDREW G. MORROW, Bethesda,
Maryland
Almost invariably the patient with aortic stenosis is referred to the cardiologist because of a precordial murmur detected by his physician. The decision as to whether cardiac catheterization and other special examinations are indicated can usually be made at the time of the initial examination. The presence of any of the now classic symptoms of angina, syncope, cardiac failure or severe exertional dyspnea constitutes almost absolute indication for prompt investigation. Exceptions to this general rule are found in those patients with aortic stenosis whose symptoms are clearly attributable to another disease process, such as pulmonary emphysema. A serious intercurrent disease or extreme age are also obvious contraindications to consideration of operation. A somewhat more difficult problem is posed by the patient who clearly has one of the forms of aortic stenosis but is entirely asymptomatic. In managing such a patient it must be remembered that the absence of symptoms by no means excludes the possibility of severe obstruction and the threat of sudden death. The age of the asymptomatic patient determines the course of procedure to some extent. The different management of the disease in children and adults is considered below.
NUMBERof different congenital and acquired cardiovascular malformations may cause obstruction to the ejection of blood from the left ventricle. The most common of these are valvular aortic stenosis, the discrete form of congenital subaortic stenosis, idiopathic hypertrophic subaortic stenosis and supravalvular narrowing of the ascending aorta. Each of these specific anatomic lesions initiates a similar chain of physiologic consequences resulting in an increased pressure load on the left ventricle, increased demand of the heart for oxygen, and, in some instances, inability of the ventricle to eject a volume of blood sufficient to sustain normal activity. The presence of an obstructing lesion in the region of the aortic valve can usually be detected on clinical examination, which may also provide some information suggesting the specific location of the obstruction and its severity. \Yhen the results of clinical studies indicate that severe obstruction may be present, the possibility of operative intervention must be considered. Methods for the surgical correction of all forms of aortic stenosis are now available, but both the risk of operation and the extent of hemodynamic improvement which can be expected afterward are dependent to a large extent upon the specific type and site of obstruction and its severity and duration. For these reasons the selection of patients for operation is greatly facilitated by detailed hemodynamic and, in some instances, angiographic assessments. Such investigations are indicated in every patient in whom the clinical examinations indicate the possibility of severe stenosis. The purpose of this report is to summarize the current indications, in this clinic, for the detailed study and surgical treatment of patients with the various lesions responsible for obstruction to left ventricular outflow.
A
* From the Cardiology JUI.Y 1963
M.D.
VALVULAR AORTIC STENOSIS AND DISCRETE SCJBVALVULAR STENOSIS IN CHILDREN Clinical Evaluation: In children or adolescents with congenital aortic stenosis, a number of clues to the severity of obstruction are provided by the physical, radiographic and electrocardiographic findings. Among 100 patients with congenital aortic stenosis whom we have studied, mild stenosis was associated with the absence of a systolic thrill and left ventricular lift; a lift and thrill were never present when the systolic pressure gradient was less than 25
Branch and Clinic of Surgery, National Heart Institute, Bethesda, Md. 53
54
mm. Hg.
Braunwald
Mild obstruction is also suggested by a short musical ejection murmur, particularly if it reaches its peak during the first third of systole. In patients under 10 years of age an S wave in lead Vi less than 16 mm., and R wave in lead Vr, less than 20 mm., and an R/S ratio in lead Vi greater than 0.40 also were found to be associated with relatively mild obstruction. The size of the heart, particularly of the left ventricle as determined by x-ray film, is normal in the absence of severe obstruction, but the converse is certainly not true since a small heart is often seen in patients with marked narrowing of the aortic valve. The clinical examination in a patient with congenital aortic stenosis also may suggest that severe obstruction is present. It may be suspected when the left ventricle is distinctly enlarged to palpation and on x-ray films. In these patients paradoxic splitting of the second heart sound is generally associated with a large gradient, and a second heart sound that remains single throughout the respiratory cycle also usually signifies marked narrowing in patients with obstruction to left ventricular outflow. A prominent presystolic ventricular lift and, in patients above the age of 12 years, a loud fourth heart sound indicate that the left ventricle is markedly hypertrophied, a finding generally reflecting severe obstruction. The electrocardiogram is less helpful ; while an S wave in Vi less than 16 mm. and an R wave in V5 less than 20 mm. are not usually seen in children with marked obstruction, the opposite is not the case, since patients in whom these voltages are exceeded do not necessarily have severe stenosis. Inversion of the T wave in the left precordial leads has been observed in our patients with gradients as low as 20 mm. Hg. Many patients with severe stenosis have prominent a waves in their jugular pulses. Indirect carotid pulse tracings usually exhibit a prominent anacrotic shoulder or notch, a rounded or delayed peak, a carotid shudder and a delayed incisura; but unfortunately none of these signs can be relied upon as a precise guide to the severity of the obstruction. Similarly, the presence or degree of poststenotic dilatation of the aorta provides little help. Hemdynamic Studies: Cardiac catheterization is certainly indicated in children over 3 years old in whom the clinical examinations indicate severe stenosis or doubt of it. Thus, detailed studies need not be made in every patient with aortic stenosis in this age group, but it is the
and Morrow physician’s responsibility to exclude severe obstruction after establishing the clinical diagnosis. When catheterization is not indicated, the child must be followed closely and catheterization performed if suspicious changes in the clinical findings, x-ray film or electrocardiogram are noted. If, on the basis of the considerations already presented, a precise assessment of the site and severity of obstruction seem to be indicated, combined right and left heart catheterization is the procedure of choice. In patients with congenital aortic stenosis right heart catheterization is helpful in detecting or excluding associated lesions such as patent ductus arteriosus, ventricular septal defect or pulmonic stenosis. In addition, pulmonary hypertension in a patient with pure aortic stenosis indicates that prompt surgical treatment should be undertaken. The systolic ,bre.wure gradient between the left ventricle and brachial artery (or preferably the central aorta) and the cardiac output are the crucial hemodynamic measurements for evaluating the severity of stenosis. In our clinic, left ventricular pressure is usually measured by transseptal left heart catheterization, and cardiac output, by the indicator-dilution technic. When the peak systolic pressure gradient is less than 45 mm. Hg and the effective area of the stenotic orifice exceeds 0.7 cm2./M2. BSA, the obstruction is considered to be mild ; in such a patient operation is not usually necessary, and selective angiocardiography is not performed. However, when the peak left ventricular-arterial gradient exceeds 45 to 50 mm. Hg, a selective angiocardiogram or cineangiocardiogram, with injection into the Ieft ventricle, is usually obtained. One of the disadvantages of the transseptal method is that it does not usually allow the recording of pressures as the catheter tip is withdrawn across the aortic valve and the Howsubvalvular and supravalvular regions. ever, a selective left ventricular angiocardiogram, performed in the course of transseptal catheterization, permits localization of the site of stenosis ; this study is also helpful in (1) distinguishing between discrete subvalvular and hypertrophic subaortic stenosis, (2) outlining the thickness of the left ventricular wall, (3) determining the mobility of the valve leaflets and (4) delineating the coronary arteries, the sinuses of Valsalva and the ascending aorta. Indications for Surgery: In patients with congenital valvular or discrete subvalvular THE
AMERICAN
JOURNAL
OF
CARDIOI.OGY
Operation
for Left Ventricular
stenosis the presence of severe obstruction is the indication for operation. Unfortuprimary the natural history of patients with nately, untreated congenital aortic stenosis, in whom the severity of obstruction has been established by left heart catheterization, is unknown. It seems unlikely that these data will ever become available since the de\.elopment of safe technics of total cardiopulmonary bypass and of open repair of congenital valvular and discrete subvalvular stenosis now permits effective treatment of these lesions. Thus, it is our current policy to recommend operation in any child with a peak systolic gradient exceeding 50 mm. Hg, measured in the basal state, or with an effective orifice of less than 0.7 cm?./M2. BSA; the somewhat arbitrary nature of these criteria Since sudden death is a must be recognized. distinct hazard in patients with severe stenosis, even when they are entirely asymptomatic, it is advisable not to postpone operation after the presence of se\‘ere stenosis has been established. Tke
optimal
age for
catheterization,
operation,
or
From the technical point of view, the smaller the patient’s aorta the more difficult For this reason, in patients is the surgeon’s task. with valvular stenosis operation is generall) deferred until the patient’s weight exceeds 15 to 17 kq. unless symptoms are ominous or heart failure and marked cardiac enlargement are present. The considerations are similar when discrete subvalvular stenosis is present. Indeed, exposure presents an e\ren greater problem in the small child with subvalvular stenosis than in one with valvular stenosis, and unless serious contraindications exist, operation for the former lesion is delayed until the child weighs 18 to 20 kg. Operations for tile r&f of aortic stenosis are now always performed during total cardiopulmonary bypass. After the institution of bypass, the esophageal temperature is reduced to approximately 30°c., and a drainage cannula is passed through the chest wall into the left ventricle through a stab wound in the apex. Following occlusion of the ascending aorta and a vertical aortotomy, the left and intermittently the right coronary artery, are perfused with oxygenated blood supplied through cannulas connected to side arms of the arterial return line. This procedure maintains oxygenation of the myocardium and obviates the impairment of left ventricular function which follows any period of ischemia. In the child with stenosis of a both,
JUI.Y
varies.
1963
Outflow
Obstruction
55
bicuspid or tricuspid valve, only division of the fused commissures is usually necessary. When discrete subaortic stenosis is present, the valve leaflets are retracted, and the obstructing fibromuscular membrane is excised, care being taken to avoid damage to the aortic leaflet of the mitral valve into which the membrane inserts. Occasionally obstruction results from a combinaThis tion of valvular and subvalvular stenosis. lesion is characterized by thickened valve leaflets and commissures that extend into a hypoplastic valve ring and a narrowed and fibrotic outflow tract. Effective surgical treatment of this lesion, which has been termed “tunnel stenosis,” is presently more difficult and less satisfactory than the treatment of either isolated valvular or discrete subvalvular stenosis, but fortunately it is encountered infrequently. The results of the operatiue treatment of 44 patients with congenital aortic stenosis in this clinic have Thirty-nine are living; recently been reviewed. four of the deaths occurred among the first 5 patients operated upon, at a time when there had been relatively little experience with the operative methods described. Postoperative left heart catheterization performed in 33 patients have shown a systolic pressure gradient less than 20 mm. Hg in 18 patients, a less satisfactory but acceptable result (gradient between 25 and 50 mm. Hg) in 10 patients and a gradient exceeding SO mm. Hg in only 5 patients. VALVULAR AORTIC STENOSISIN THE ADULT The adult patient with obstruction to left ventricular outflow presents problems that differ from those presented by the child. Although considerable progress has been made in the surgical treatment of calcific aortic stenosis, and operative mortality and morbidity have steadily declined, the results of operation are still not as salutary as in congenital aortic stenosis. The difference between results of operation in children and in adults is not related to the fact that the lesion is congenital in children and It is largely attribusually acquired in adults. utable to the extensive deformity and calcification of the valve which almost invariably occur in adults, regardless of the etiology. In order to restore satisfactory valve function, the leaflets must first be made mobile by removal of the calcific and atheromatous deposits on their surfaces and in the depths of the sinuses of Valsalva. Following this, an increased orifice is achieved by incision of the fused commissures. In many adult patients with calcific aortic
56
Braunwald
stenosis, effective debridement cannot be accomplished without the destruction of valvular tissue, and excision and prosthetic replacement of all or a portion of the valve is frequently necessary. In addition to these important technical considerations, left ventricular function is compromised with aortic stenosis more often in older patients than in children. Finally, the more frequent association of significant coronary atherosclerosis and of other valvular abnormalities are reasons for a somewhat more conservative approach in the adult than in the child with aortic stenosis. Indications for Operation: It is now quite clear that the outlook for survival is limited in the adult patient with symptoms resulting primarily from aortic stenosis. If, in such a patient, the peak left ventricular-arterial gradient exceeds 50 mm. Hg, and if the effective aortic orifice is reduced to less than 0.7 cm2./M2. BSA, operation is clearly indicated. However, the asymptomatic patient with severe calcific aortic stenosis poses a more difficult problem. The prognosis in such patients is not necessarily poor, and it is possible that they may survive for a number of years before disability develops. Under these circumstances, it now seems prudent to postpone surgical consideration in the totally asymptomatic adult with aortic stenosis. It is likely, however, that if such patients were operated upon, the risk would be extremely low, and it is possible that our current policy will be altered. As the experience with prosthetic aortic valves increases, and when it becomes clear that the initial favorable results of partial and of total replacement of valves will be maintained for many years, the attitude toward the adult patient with asymptomatic aortic stenosis will certainly change. Then many of these patients will become candidates for operation. Associated Coronary Artery Disease: A special problem is posed by the patient with severe calcific aortic stenosis and clear evidence of coronary artery disease. The latter diagnosis is not, of course, indicated by the presence of angina pectoris alone since this symptom is one of the cardinal ones in severe aortic stenosis The diagnosis without coronary artery disease. of coronary artery disease must, therefore, rest on a clear-cut history of one or more myocardial electrocardiographic evidence of infarctions, previous infarction, or unequivocal abnormalities in a coronary arteriogram. When severe aortic stenosis and coronary artery disease
and Morrow coexist, relief of stenosis often results in striking clinical improvement, presumably because of the diminution of the pressure load on the left ventricle and the resultant decrease in myocardial requirements for oxygen. However. the physician, the surgeon and the patient must understand that operation can relieve only one aspect of the patient’s disease and that the presence of associated coronary artery disease raises the risk of operation and somewhat diminishes the likelihood of complete symptomatic recovery. With these considerations in mind, it is the policy in this clinic to recommend operation for patients with aortic stenosis and coronary artery disease when the hemodynamic evidence of severe obstruction to left ventricular outflow is unequivocal. When Combined dortic Stenosis and Insuficiency: it is clear from the clinical examination that other valvular dysfunction is present, precise hemodynamic evaluation of the relative importance of the valvular lesions associated with aortic stenosis is mandatory. Small degrees of aortic regurgitation not associated with widening of the pulse pressure, with lowering of the diastolic arterial pressure, or with a bisferiens pulse in the carotid vessels need not affect the plan of management. However, when predominant aortic stenosis is accompanied by a moderate degree of aortic regurgitation as manifested by (1) a pulse pressure exceeding 55 mm. Hg and a diastolic arterial pressure below 60 mm. Hg, (2) by reflux of indicator dye from the aorta at a level below the seventh thoracic vertebra to the origin of the innominate artery, or (3) by complete opacification of the left ventricle following thoracic aortography, experience has shown that normal or near-normal aortic valve function can seldom be accomplished by debridement and commissurotomy. In such a patient it may be anticipated that complete replacement of the aortic valve will be In spite of the encouraging early necessary. results of such procedures, as already mentioned, the long term fate of prosthetic valves is not yet When preoperative studies indicate that clear. a prosthesis will probably be necessary, it is reasonable to recommend operation only if the patient’s symptoms interfere with his normal activities or if they are clearly progressive. When Combined Mitral and Aortic Stenosis: each lesion is severe enough to warrant operation, a combined valvulotomy is indicated. In such patients the left ventricle is usually less hypertrophied, friable and irritable than when ‘THEAMERICAN
JOURNAL
OF
CARDIOLOGY
Operation
for Left
Ventricular
aortic stenosis alone exists. Of even greater importance, calcification and deformity of the aortic valve tends to be less extensive when the combined lesion is present. It appears likely that the presence of the mitral stenosis in such patients leads to cardiac disability and brings them to the attention of the cardiologist at an earlier stage of their illness than when aortic stenosis alone is present. As a result, those with combined mitral and aortic stenosis are usually referred for operation before extensive calcification of the aortic valve has occurred, and a satisfactory operative result can often be obtained without insertion of an aortic valve prosthesis. Indeed, in some instances, closed transventricular mitral and aortic valvulotomies permit effective relief of obstruction of both closed transventricular valves. In contrast, aortic valvulotomy should no longer be considered in an)- patient with pure aortic stenosis. Congest& Heart 1:ailure: Fortunately, the majority of patients with pure aortic stenosis are now referred for surgical consideration before they reach the stage of intractable congestive heart failure, characterized by marked cardiomegaly, pulmonary hypertension, tricuspid regurgitation. peripheral edema and sometimes The management of patients atria1 fibrillation. presenting this clinical picture is particularly difficult. While it is clear that the prognosis without operation is indeed dismal, the risk of Not uncommonly operation is extremel\. high. in patients with aortic stenosis and intractable heart failure, irreversible ventricular fibrillation develops during the induction of anesthesia or during the thoracotomy, before cardiopulmonar>- by-pass can be instituted. At the present time, it is the attitude in this clinic that this disease process can be likened to a rapidly advancing rnalignant neoplasm, and that radical measures may be required to Acsalvage even a fraction of the patients. cordingly, operation is not withheld from any patient on the basis of the advanced nature of the disease. The extent to which the myocardial function of such patients can be improved by valve replacement will be the criterion by which the current attitude will be judged, and possibly revised, in the future. SUPRAVALVULAR AORTIC STENOSIS Congenital supravalvular aortic stenosis is a relatively uncommon anomaly, and far less information is available concerning its natural history than exists for valvular or discrete
Outflow
Obstruction
57
Similarly, there has been subvalvular stenosis. relatively little surgical experience with this malformation. Supravalvular aortic stenosis is often associated with hypoplasia of the ascendIt may be suspected clinically when, ing aorta. on x-ray examination, there is no evidence of poststenotic dilatation of the aorta or of an enlarged aortic knob, but when the thrill and murmur along the carotid vessels are unusually prominent. In some instances the lesion has been found to occur in a familial form, and in others, to be associated with mental retardation and a characteristic facies. When selective left ventricular angiocardiography reveals the presence of supravalvulat aortic stenosis, it is helpful to perform retrograde arterial catheterization. The recording of a withdrawal pressure tracing in the central aorta permits evaluation of the hemodynamic severity of the multiple obstructions which may occur Although the coronary as a part of this lesion. arteries are tremendously enlarged in the presence of supravalvular aortic stenosis, it must be appreciated that in some patients coronary filling is impeded by fibrous bands coursing between the primary site of obstruction and the upper margins of the sinuses of Valsalva. While the surgical treatment of supravalvular aortic stenosis is feasible, it must be appreciated that it is usually more difficult and less effective than the surgical relief of either congenital valvular or discrete subvalvular stenosis. Although the diameter of the obstructing supravalvular ring can be increased by the insertion of a diamond-shaped plastic prosthesis, a hypoplastic ascending aorta may then become the critical area of narrowing. The pressure gradient is then displaced, but not abolished, and the pressure load on the left ventricle persists. It appears that in many patients with supravalvular stenosis, totally effective surgical treatment may require replacement or widening of the entire hypoplastic aorta with an appropriate prosthesis. Because of the above considerations, the criteria for the selection of patients with supravalvular obstruction are stricter than for those with other forms of congenital aortic stenosis. Ideally there should be relatively little hypoplasia of the ascending aorta and arch, and severe, discrete obstruction, i.e., a systolic gradient exceeding 80 mm. Hg when measured in the basal state. In asymptomatic patients with milder obstruction operation is now deferred.
58 IDIOPATHIC
Braunwald HYPERTROPHICSUBAORTIC
STENOSIS
Hypertrophic subaortic stenosis is uncommon in comparison to valvular aortic stenosis. However, the large number of recent reports describing patients with this lesion makes it mandatory to consider it in the differential diagnosis of obstruction to left ventricular Outflow in patients of all age groups. The clinical and hemodynamic features which should suggest the presence of this lesion and those which tend to exclude it are now well recognized. When the diagnosis of idiopathic hypertrophic subaortic stenosis has been established and surgical treatment considered, it is essential to keep the basic nature of the disease process in mind. There is increasing evidence that the disease is a diffuse myocardial one that may involve both ventricles and, in some patients, results in obstruction to ventricular outflow. It is clear that it is now feasible to incise or resect, or both, a portion of the obstructing muscle and either abolish or greatly reduce the intraventricular pressure gradient. However, it must be appreciated that, even when surgical relief of the obstruction is completely successful, the underlying disease process responsible for the muscular hypertrophy remains unaltered. In this connection, it is now known that angina pectoris, congestive heart failure, or even sudden death can occur in the patients with hypertrophic subaortic stenosis and only mild outflow obstruction and even in those with idiopathic left ventricular hypertrophy without obstruction. Conversely, many patients with hypertrophic subaortic stenosis, mild heart failure or syncobe, or both, exhibit a chronic course, with little further diminution of cardiovascular reserve over a period of many years. This is in contrast to the patients with valvular aortic stenosis who rarely survive for a prolonged period after heart failure or syncope, or both, develop. Operative Indications and Results: Nonetheless, the anatomic variations of idiopathic hypertrophic subaortic stenosis are such that in some patients obstruction to left ventricular outflow is extremely severe, and the excessive pressure load on the lower portion of the ventricle must be responsible for further ventricular hypertrophy. If it is clear that severe obstruction is consistently present, and if the patient is severely disabled by the disease, operation is advised. A peak systolic gradient exceeding 70 mm. Hg and an effective orifice Iess than 0.5 cm2./M2.
and
Morrow
BSA was present in all 6 patients with idiopathic hypertrophic subaortic stenosis who have been operated upon in this clinic. All 6 have survived operation; the obstruction has been completely, or almost completely, abolished ; and they have experienced dramatic relief of symptoms. Operation appeared to be lifesaving in 3 of these patients who were in intractable heart failure or who had progressively more frequent and longer syncopal episodes. These results are certainly encouraging, and it is hoped that the diffuse myocardial hypertrophy will not result in recurrent obstruction nor progressively interfere with myocardial function. SUMMARY
The current criteria for the selection for operation of patients with the various forms of obstruction to left ventricular outflow are reviewed. In children or adolescents with congenital valvular or discrete subvalvular stenosis, left heart catheterization should he performed whenever the clinical examinations indicate or suggest the possibility that severe stenosis is present. Operation is recommended in children with peak systolic pressure gradients between the left ventricle and brachial artery which exceed 50 mm. Hg or with an effective orifice less than 0.7 cm2./M2. BSA. It is now quite clear that the outlook for survival is limited in the adult with symptoms resulting from aortic stenosis, and operation is recommended when the peak systolic left ventriculararterial pressure gradient exceeds 50 mm. Hg. In many adult patients with calcific aortic stenosis, effective debridement cannot be accomplished without the destruction of valvular tissue, and excision and prosthetic replacement of at least a portion of the valve is frequently necessary. Accordingly, surgical consideration is postponed in the totally asymptomatic adult. The surgical treatment of supravalvular aortic stenosis and of idiopathic hypertrophic subaortic stenosis is usually more difficult and less effective than the surgical relief of congenital valvular or discrete subvalvular stenosis. The criteria for the selection for operation of patients with these less common forms of obstruction to left ventricular outflow are stricter than for those with the more common forms of obstruction ; the combination of severe narrowing and serious or progressive symptoms are required before operation is recommended. 'THE AMERICANJOURNALOF
CARDIOLOGY
Operation
for Left Ventricular
Outflow
Obstruction
of congenital H. T., SPENCER,F. C., BUSSE, E. F. and DAVID, F. W., JR. Cusp replacement and coronary artery perfusion in open operations on the aortic valve. Ann. Surg., 152: 494, 1960. 2. BRAUNM’ALD,E.. BROCKENBROUGH, E. C., TAIXERT, J. L., FOI.SE, J. R. and ROCKOFF, S. D. Selective left h(.art angiocardiography by the transseptal route. Am. .J. Med., 33: 213, 1962. 3. BRAUN\VILD, E., GI~LDBLATT,A., AYGEN, M. M., ROCKOFF, S. D. and MORROW, A. G. Congenital aortic stenosis. I. Clinical and hemodynamic findings in 100 patients. Circulntion, 27 : 426, 1963. 4. BRAUN~ALD, E., MORROW, A. G., CORNELL, W. P., AYGER., M. M. and HILBISH, T. F. Idiopathic hypertrophic subaortic stenosis: clinical, hemodynamic and anyiographic manifestations. .4m. 1. RAHNSON,
J. .2fed., 29: 924, 1960. 5. BRAUN~ALD. E. et al.
Clinical staff conference. Aortic stc.nosis: physiological, pathological, and clinic;ll concepts. Ann. ht. Med., 58: 494, 1963. 6. ELI.IS. E’. H. and KIRKLIN, J. W. Congenital valx-ular aortic stenosis: anatomic findings and surqical technique. J. Thor&c & Cnrdiooas. Surg.,
43: 199, 1962. 7. ELLIS, 1:. H., ONGLEY, P. A. and KIRKLIN, 3. W.
Results of surgical treatment for congenital aortic stenosis. Circulatzon, 25: 29, 1962. 8. GOLDRLATT,A., AXEN, M. M. and BRAUNWALD,E. Hemodynamic-phonocardiographic correlations of the fourth heart sound in aortic stenosis. Circulatzon, 26: 92, 1962. 9. HUFNAGEL, C. A. and
aortic stenosis.
CONRAD, P. W.
Yew England J. Med.,
Calcific 266:
72.
1962. 10. HUGENFIOL.TZ, P. G., LEES, M. M. and NADAS, A. S.
The scalar electrocardiogram, vectorcardiogram, and exercise elecrrocardiogram in the assessment
.JULY 1963
aortic stenosis.
59 Circulntion. 26: 79.
1962.
11. KAY, E. B., MENDEUOHN. D.. JR. and ZIMMERMAN, H. A. Surgical treatment of aortic valvular disease by prosthetic replacement. .l?n. J. Cnrdiol., 9: 284,
1962.
12. LEES. M. H., HAUC,K,A. J., STARKEY,G. B., NADAS,
.4. S. and GROSS. R. E. Congenital aortic stenosis: operative Indications and surgical results. Brit. Heart J., 24: 31, 1962.
McGo~N, D. C., MANKIN, H. T. and KIRKLIN, J. W. Results of open operation for acquired aortic valve disease. J. Thor& tZ Card&m. Surg., in press. 14. MORROXV.A. G., :\USTEN.W. G. and BRAUNWALD, E. The surgical treatment of calcific aortic stenosis: oprrative methods and the results of pre- and postoperative hemodynamic assessments. Ann. Surg., in press. 15. MORROM~.A. G., .\w~, \V. C and BRAUNWALD.E. Combined mitral and aortic stenosis. Brit. Hmrt
13.
J., 24: 606,
1962.
16. MORROW. A. G., GOLDBLATT, A. and BRAUN~ALD,
E. Congenital aortic stenosis. II. Surgical treatment and the results of operation. Cbmlation. 27: 450. 1963. 17. MORROW, A. G., WALDHAUSEN,I. A., PETERS:R. L.,
BLOOUWELL,R. D. and BRAUN~ALD. E. Supravalvular aortic stenosis: clinical, hemodynamic, and pathologic observations. Circulntion, 20: 1003, 1959.
18 MUUER, IV. H., JR., LITTLEFIELD,J. G. and DAMMANN..I. F., .JR. Subcoronary prosthetic replacement of the aortic valve. In: Conference on Prosthetic Valves for Cardiac Surgery, p. 493. Edited by ~~ERENDINO,K. A. Sprin$ield. Ill., 1961. Charles C Thomas.
to Left Ventricular
Outflow
Current Criteria for the Selection of Patients for Operation* E~JCENE BRAUNWALD, M.D. and ANDREW G. MORROW, Bethesda,
Maryland
Almost invariably the patient with aortic stenosis is referred to the cardiologist because of a precordial murmur detected by his physician. The decision as to whether cardiac catheterization and other special examinations are indicated can usually be made at the time of the initial examination. The presence of any of the now classic symptoms of angina, syncope, cardiac failure or severe exertional dyspnea constitutes almost absolute indication for prompt investigation. Exceptions to this general rule are found in those patients with aortic stenosis whose symptoms are clearly attributable to another disease process, such as pulmonary emphysema. A serious intercurrent disease or extreme age are also obvious contraindications to consideration of operation. A somewhat more difficult problem is posed by the patient who clearly has one of the forms of aortic stenosis but is entirely asymptomatic. In managing such a patient it must be remembered that the absence of symptoms by no means excludes the possibility of severe obstruction and the threat of sudden death. The age of the asymptomatic patient determines the course of procedure to some extent. The different management of the disease in children and adults is considered below.
NUMBERof different congenital and acquired cardiovascular malformations may cause obstruction to the ejection of blood from the left ventricle. The most common of these are valvular aortic stenosis, the discrete form of congenital subaortic stenosis, idiopathic hypertrophic subaortic stenosis and supravalvular narrowing of the ascending aorta. Each of these specific anatomic lesions initiates a similar chain of physiologic consequences resulting in an increased pressure load on the left ventricle, increased demand of the heart for oxygen, and, in some instances, inability of the ventricle to eject a volume of blood sufficient to sustain normal activity. The presence of an obstructing lesion in the region of the aortic valve can usually be detected on clinical examination, which may also provide some information suggesting the specific location of the obstruction and its severity. \Yhen the results of clinical studies indicate that severe obstruction may be present, the possibility of operative intervention must be considered. Methods for the surgical correction of all forms of aortic stenosis are now available, but both the risk of operation and the extent of hemodynamic improvement which can be expected afterward are dependent to a large extent upon the specific type and site of obstruction and its severity and duration. For these reasons the selection of patients for operation is greatly facilitated by detailed hemodynamic and, in some instances, angiographic assessments. Such investigations are indicated in every patient in whom the clinical examinations indicate the possibility of severe stenosis. The purpose of this report is to summarize the current indications, in this clinic, for the detailed study and surgical treatment of patients with the various lesions responsible for obstruction to left ventricular outflow.
A
* From the Cardiology JUI.Y 1963
M.D.
VALVULAR AORTIC STENOSIS AND DISCRETE SCJBVALVULAR STENOSIS IN CHILDREN Clinical Evaluation: In children or adolescents with congenital aortic stenosis, a number of clues to the severity of obstruction are provided by the physical, radiographic and electrocardiographic findings. Among 100 patients with congenital aortic stenosis whom we have studied, mild stenosis was associated with the absence of a systolic thrill and left ventricular lift; a lift and thrill were never present when the systolic pressure gradient was less than 25
Branch and Clinic of Surgery, National Heart Institute, Bethesda, Md. 53
54
mm. Hg.
Braunwald
Mild obstruction is also suggested by a short musical ejection murmur, particularly if it reaches its peak during the first third of systole. In patients under 10 years of age an S wave in lead Vi less than 16 mm., and R wave in lead Vr, less than 20 mm., and an R/S ratio in lead Vi greater than 0.40 also were found to be associated with relatively mild obstruction. The size of the heart, particularly of the left ventricle as determined by x-ray film, is normal in the absence of severe obstruction, but the converse is certainly not true since a small heart is often seen in patients with marked narrowing of the aortic valve. The clinical examination in a patient with congenital aortic stenosis also may suggest that severe obstruction is present. It may be suspected when the left ventricle is distinctly enlarged to palpation and on x-ray films. In these patients paradoxic splitting of the second heart sound is generally associated with a large gradient, and a second heart sound that remains single throughout the respiratory cycle also usually signifies marked narrowing in patients with obstruction to left ventricular outflow. A prominent presystolic ventricular lift and, in patients above the age of 12 years, a loud fourth heart sound indicate that the left ventricle is markedly hypertrophied, a finding generally reflecting severe obstruction. The electrocardiogram is less helpful ; while an S wave in Vi less than 16 mm. and an R wave in V5 less than 20 mm. are not usually seen in children with marked obstruction, the opposite is not the case, since patients in whom these voltages are exceeded do not necessarily have severe stenosis. Inversion of the T wave in the left precordial leads has been observed in our patients with gradients as low as 20 mm. Hg. Many patients with severe stenosis have prominent a waves in their jugular pulses. Indirect carotid pulse tracings usually exhibit a prominent anacrotic shoulder or notch, a rounded or delayed peak, a carotid shudder and a delayed incisura; but unfortunately none of these signs can be relied upon as a precise guide to the severity of the obstruction. Similarly, the presence or degree of poststenotic dilatation of the aorta provides little help. Hemdynamic Studies: Cardiac catheterization is certainly indicated in children over 3 years old in whom the clinical examinations indicate severe stenosis or doubt of it. Thus, detailed studies need not be made in every patient with aortic stenosis in this age group, but it is the
and Morrow physician’s responsibility to exclude severe obstruction after establishing the clinical diagnosis. When catheterization is not indicated, the child must be followed closely and catheterization performed if suspicious changes in the clinical findings, x-ray film or electrocardiogram are noted. If, on the basis of the considerations already presented, a precise assessment of the site and severity of obstruction seem to be indicated, combined right and left heart catheterization is the procedure of choice. In patients with congenital aortic stenosis right heart catheterization is helpful in detecting or excluding associated lesions such as patent ductus arteriosus, ventricular septal defect or pulmonic stenosis. In addition, pulmonary hypertension in a patient with pure aortic stenosis indicates that prompt surgical treatment should be undertaken. The systolic ,bre.wure gradient between the left ventricle and brachial artery (or preferably the central aorta) and the cardiac output are the crucial hemodynamic measurements for evaluating the severity of stenosis. In our clinic, left ventricular pressure is usually measured by transseptal left heart catheterization, and cardiac output, by the indicator-dilution technic. When the peak systolic pressure gradient is less than 45 mm. Hg and the effective area of the stenotic orifice exceeds 0.7 cm2./M2. BSA, the obstruction is considered to be mild ; in such a patient operation is not usually necessary, and selective angiocardiography is not performed. However, when the peak left ventricular-arterial gradient exceeds 45 to 50 mm. Hg, a selective angiocardiogram or cineangiocardiogram, with injection into the Ieft ventricle, is usually obtained. One of the disadvantages of the transseptal method is that it does not usually allow the recording of pressures as the catheter tip is withdrawn across the aortic valve and the Howsubvalvular and supravalvular regions. ever, a selective left ventricular angiocardiogram, performed in the course of transseptal catheterization, permits localization of the site of stenosis ; this study is also helpful in (1) distinguishing between discrete subvalvular and hypertrophic subaortic stenosis, (2) outlining the thickness of the left ventricular wall, (3) determining the mobility of the valve leaflets and (4) delineating the coronary arteries, the sinuses of Valsalva and the ascending aorta. Indications for Surgery: In patients with congenital valvular or discrete subvalvular THE
AMERICAN
JOURNAL
OF
CARDIOI.OGY
Operation
for Left Ventricular
stenosis the presence of severe obstruction is the indication for operation. Unfortuprimary the natural history of patients with nately, untreated congenital aortic stenosis, in whom the severity of obstruction has been established by left heart catheterization, is unknown. It seems unlikely that these data will ever become available since the de\.elopment of safe technics of total cardiopulmonary bypass and of open repair of congenital valvular and discrete subvalvular stenosis now permits effective treatment of these lesions. Thus, it is our current policy to recommend operation in any child with a peak systolic gradient exceeding 50 mm. Hg, measured in the basal state, or with an effective orifice of less than 0.7 cm?./M2. BSA; the somewhat arbitrary nature of these criteria Since sudden death is a must be recognized. distinct hazard in patients with severe stenosis, even when they are entirely asymptomatic, it is advisable not to postpone operation after the presence of se\‘ere stenosis has been established. Tke
optimal
age for
catheterization,
operation,
or
From the technical point of view, the smaller the patient’s aorta the more difficult For this reason, in patients is the surgeon’s task. with valvular stenosis operation is generall) deferred until the patient’s weight exceeds 15 to 17 kq. unless symptoms are ominous or heart failure and marked cardiac enlargement are present. The considerations are similar when discrete subvalvular stenosis is present. Indeed, exposure presents an e\ren greater problem in the small child with subvalvular stenosis than in one with valvular stenosis, and unless serious contraindications exist, operation for the former lesion is delayed until the child weighs 18 to 20 kg. Operations for tile r&f of aortic stenosis are now always performed during total cardiopulmonary bypass. After the institution of bypass, the esophageal temperature is reduced to approximately 30°c., and a drainage cannula is passed through the chest wall into the left ventricle through a stab wound in the apex. Following occlusion of the ascending aorta and a vertical aortotomy, the left and intermittently the right coronary artery, are perfused with oxygenated blood supplied through cannulas connected to side arms of the arterial return line. This procedure maintains oxygenation of the myocardium and obviates the impairment of left ventricular function which follows any period of ischemia. In the child with stenosis of a both,
JUI.Y
varies.
1963
Outflow
Obstruction
55
bicuspid or tricuspid valve, only division of the fused commissures is usually necessary. When discrete subaortic stenosis is present, the valve leaflets are retracted, and the obstructing fibromuscular membrane is excised, care being taken to avoid damage to the aortic leaflet of the mitral valve into which the membrane inserts. Occasionally obstruction results from a combinaThis tion of valvular and subvalvular stenosis. lesion is characterized by thickened valve leaflets and commissures that extend into a hypoplastic valve ring and a narrowed and fibrotic outflow tract. Effective surgical treatment of this lesion, which has been termed “tunnel stenosis,” is presently more difficult and less satisfactory than the treatment of either isolated valvular or discrete subvalvular stenosis, but fortunately it is encountered infrequently. The results of the operatiue treatment of 44 patients with congenital aortic stenosis in this clinic have Thirty-nine are living; recently been reviewed. four of the deaths occurred among the first 5 patients operated upon, at a time when there had been relatively little experience with the operative methods described. Postoperative left heart catheterization performed in 33 patients have shown a systolic pressure gradient less than 20 mm. Hg in 18 patients, a less satisfactory but acceptable result (gradient between 25 and 50 mm. Hg) in 10 patients and a gradient exceeding SO mm. Hg in only 5 patients. VALVULAR AORTIC STENOSISIN THE ADULT The adult patient with obstruction to left ventricular outflow presents problems that differ from those presented by the child. Although considerable progress has been made in the surgical treatment of calcific aortic stenosis, and operative mortality and morbidity have steadily declined, the results of operation are still not as salutary as in congenital aortic stenosis. The difference between results of operation in children and in adults is not related to the fact that the lesion is congenital in children and It is largely attribusually acquired in adults. utable to the extensive deformity and calcification of the valve which almost invariably occur in adults, regardless of the etiology. In order to restore satisfactory valve function, the leaflets must first be made mobile by removal of the calcific and atheromatous deposits on their surfaces and in the depths of the sinuses of Valsalva. Following this, an increased orifice is achieved by incision of the fused commissures. In many adult patients with calcific aortic
56
Braunwald
stenosis, effective debridement cannot be accomplished without the destruction of valvular tissue, and excision and prosthetic replacement of all or a portion of the valve is frequently necessary. In addition to these important technical considerations, left ventricular function is compromised with aortic stenosis more often in older patients than in children. Finally, the more frequent association of significant coronary atherosclerosis and of other valvular abnormalities are reasons for a somewhat more conservative approach in the adult than in the child with aortic stenosis. Indications for Operation: It is now quite clear that the outlook for survival is limited in the adult patient with symptoms resulting primarily from aortic stenosis. If, in such a patient, the peak left ventricular-arterial gradient exceeds 50 mm. Hg, and if the effective aortic orifice is reduced to less than 0.7 cm2./M2. BSA, operation is clearly indicated. However, the asymptomatic patient with severe calcific aortic stenosis poses a more difficult problem. The prognosis in such patients is not necessarily poor, and it is possible that they may survive for a number of years before disability develops. Under these circumstances, it now seems prudent to postpone surgical consideration in the totally asymptomatic adult with aortic stenosis. It is likely, however, that if such patients were operated upon, the risk would be extremely low, and it is possible that our current policy will be altered. As the experience with prosthetic aortic valves increases, and when it becomes clear that the initial favorable results of partial and of total replacement of valves will be maintained for many years, the attitude toward the adult patient with asymptomatic aortic stenosis will certainly change. Then many of these patients will become candidates for operation. Associated Coronary Artery Disease: A special problem is posed by the patient with severe calcific aortic stenosis and clear evidence of coronary artery disease. The latter diagnosis is not, of course, indicated by the presence of angina pectoris alone since this symptom is one of the cardinal ones in severe aortic stenosis The diagnosis without coronary artery disease. of coronary artery disease must, therefore, rest on a clear-cut history of one or more myocardial electrocardiographic evidence of infarctions, previous infarction, or unequivocal abnormalities in a coronary arteriogram. When severe aortic stenosis and coronary artery disease
and Morrow coexist, relief of stenosis often results in striking clinical improvement, presumably because of the diminution of the pressure load on the left ventricle and the resultant decrease in myocardial requirements for oxygen. However. the physician, the surgeon and the patient must understand that operation can relieve only one aspect of the patient’s disease and that the presence of associated coronary artery disease raises the risk of operation and somewhat diminishes the likelihood of complete symptomatic recovery. With these considerations in mind, it is the policy in this clinic to recommend operation for patients with aortic stenosis and coronary artery disease when the hemodynamic evidence of severe obstruction to left ventricular outflow is unequivocal. When Combined dortic Stenosis and Insuficiency: it is clear from the clinical examination that other valvular dysfunction is present, precise hemodynamic evaluation of the relative importance of the valvular lesions associated with aortic stenosis is mandatory. Small degrees of aortic regurgitation not associated with widening of the pulse pressure, with lowering of the diastolic arterial pressure, or with a bisferiens pulse in the carotid vessels need not affect the plan of management. However, when predominant aortic stenosis is accompanied by a moderate degree of aortic regurgitation as manifested by (1) a pulse pressure exceeding 55 mm. Hg and a diastolic arterial pressure below 60 mm. Hg, (2) by reflux of indicator dye from the aorta at a level below the seventh thoracic vertebra to the origin of the innominate artery, or (3) by complete opacification of the left ventricle following thoracic aortography, experience has shown that normal or near-normal aortic valve function can seldom be accomplished by debridement and commissurotomy. In such a patient it may be anticipated that complete replacement of the aortic valve will be In spite of the encouraging early necessary. results of such procedures, as already mentioned, the long term fate of prosthetic valves is not yet When preoperative studies indicate that clear. a prosthesis will probably be necessary, it is reasonable to recommend operation only if the patient’s symptoms interfere with his normal activities or if they are clearly progressive. When Combined Mitral and Aortic Stenosis: each lesion is severe enough to warrant operation, a combined valvulotomy is indicated. In such patients the left ventricle is usually less hypertrophied, friable and irritable than when ‘THEAMERICAN
JOURNAL
OF
CARDIOLOGY
Operation
for Left
Ventricular
aortic stenosis alone exists. Of even greater importance, calcification and deformity of the aortic valve tends to be less extensive when the combined lesion is present. It appears likely that the presence of the mitral stenosis in such patients leads to cardiac disability and brings them to the attention of the cardiologist at an earlier stage of their illness than when aortic stenosis alone is present. As a result, those with combined mitral and aortic stenosis are usually referred for operation before extensive calcification of the aortic valve has occurred, and a satisfactory operative result can often be obtained without insertion of an aortic valve prosthesis. Indeed, in some instances, closed transventricular mitral and aortic valvulotomies permit effective relief of obstruction of both closed transventricular valves. In contrast, aortic valvulotomy should no longer be considered in an)- patient with pure aortic stenosis. Congest& Heart 1:ailure: Fortunately, the majority of patients with pure aortic stenosis are now referred for surgical consideration before they reach the stage of intractable congestive heart failure, characterized by marked cardiomegaly, pulmonary hypertension, tricuspid regurgitation. peripheral edema and sometimes The management of patients atria1 fibrillation. presenting this clinical picture is particularly difficult. While it is clear that the prognosis without operation is indeed dismal, the risk of Not uncommonly operation is extremel\. high. in patients with aortic stenosis and intractable heart failure, irreversible ventricular fibrillation develops during the induction of anesthesia or during the thoracotomy, before cardiopulmonar>- by-pass can be instituted. At the present time, it is the attitude in this clinic that this disease process can be likened to a rapidly advancing rnalignant neoplasm, and that radical measures may be required to Acsalvage even a fraction of the patients. cordingly, operation is not withheld from any patient on the basis of the advanced nature of the disease. The extent to which the myocardial function of such patients can be improved by valve replacement will be the criterion by which the current attitude will be judged, and possibly revised, in the future. SUPRAVALVULAR AORTIC STENOSIS Congenital supravalvular aortic stenosis is a relatively uncommon anomaly, and far less information is available concerning its natural history than exists for valvular or discrete
Outflow
Obstruction
57
Similarly, there has been subvalvular stenosis. relatively little surgical experience with this malformation. Supravalvular aortic stenosis is often associated with hypoplasia of the ascendIt may be suspected clinically when, ing aorta. on x-ray examination, there is no evidence of poststenotic dilatation of the aorta or of an enlarged aortic knob, but when the thrill and murmur along the carotid vessels are unusually prominent. In some instances the lesion has been found to occur in a familial form, and in others, to be associated with mental retardation and a characteristic facies. When selective left ventricular angiocardiography reveals the presence of supravalvulat aortic stenosis, it is helpful to perform retrograde arterial catheterization. The recording of a withdrawal pressure tracing in the central aorta permits evaluation of the hemodynamic severity of the multiple obstructions which may occur Although the coronary as a part of this lesion. arteries are tremendously enlarged in the presence of supravalvular aortic stenosis, it must be appreciated that in some patients coronary filling is impeded by fibrous bands coursing between the primary site of obstruction and the upper margins of the sinuses of Valsalva. While the surgical treatment of supravalvular aortic stenosis is feasible, it must be appreciated that it is usually more difficult and less effective than the surgical relief of either congenital valvular or discrete subvalvular stenosis. Although the diameter of the obstructing supravalvular ring can be increased by the insertion of a diamond-shaped plastic prosthesis, a hypoplastic ascending aorta may then become the critical area of narrowing. The pressure gradient is then displaced, but not abolished, and the pressure load on the left ventricle persists. It appears that in many patients with supravalvular stenosis, totally effective surgical treatment may require replacement or widening of the entire hypoplastic aorta with an appropriate prosthesis. Because of the above considerations, the criteria for the selection of patients with supravalvular obstruction are stricter than for those with other forms of congenital aortic stenosis. Ideally there should be relatively little hypoplasia of the ascending aorta and arch, and severe, discrete obstruction, i.e., a systolic gradient exceeding 80 mm. Hg when measured in the basal state. In asymptomatic patients with milder obstruction operation is now deferred.
58 IDIOPATHIC
Braunwald HYPERTROPHICSUBAORTIC
STENOSIS
Hypertrophic subaortic stenosis is uncommon in comparison to valvular aortic stenosis. However, the large number of recent reports describing patients with this lesion makes it mandatory to consider it in the differential diagnosis of obstruction to left ventricular Outflow in patients of all age groups. The clinical and hemodynamic features which should suggest the presence of this lesion and those which tend to exclude it are now well recognized. When the diagnosis of idiopathic hypertrophic subaortic stenosis has been established and surgical treatment considered, it is essential to keep the basic nature of the disease process in mind. There is increasing evidence that the disease is a diffuse myocardial one that may involve both ventricles and, in some patients, results in obstruction to ventricular outflow. It is clear that it is now feasible to incise or resect, or both, a portion of the obstructing muscle and either abolish or greatly reduce the intraventricular pressure gradient. However, it must be appreciated that, even when surgical relief of the obstruction is completely successful, the underlying disease process responsible for the muscular hypertrophy remains unaltered. In this connection, it is now known that angina pectoris, congestive heart failure, or even sudden death can occur in the patients with hypertrophic subaortic stenosis and only mild outflow obstruction and even in those with idiopathic left ventricular hypertrophy without obstruction. Conversely, many patients with hypertrophic subaortic stenosis, mild heart failure or syncobe, or both, exhibit a chronic course, with little further diminution of cardiovascular reserve over a period of many years. This is in contrast to the patients with valvular aortic stenosis who rarely survive for a prolonged period after heart failure or syncope, or both, develop. Operative Indications and Results: Nonetheless, the anatomic variations of idiopathic hypertrophic subaortic stenosis are such that in some patients obstruction to left ventricular outflow is extremely severe, and the excessive pressure load on the lower portion of the ventricle must be responsible for further ventricular hypertrophy. If it is clear that severe obstruction is consistently present, and if the patient is severely disabled by the disease, operation is advised. A peak systolic gradient exceeding 70 mm. Hg and an effective orifice Iess than 0.5 cm2./M2.
and
Morrow
BSA was present in all 6 patients with idiopathic hypertrophic subaortic stenosis who have been operated upon in this clinic. All 6 have survived operation; the obstruction has been completely, or almost completely, abolished ; and they have experienced dramatic relief of symptoms. Operation appeared to be lifesaving in 3 of these patients who were in intractable heart failure or who had progressively more frequent and longer syncopal episodes. These results are certainly encouraging, and it is hoped that the diffuse myocardial hypertrophy will not result in recurrent obstruction nor progressively interfere with myocardial function. SUMMARY
The current criteria for the selection for operation of patients with the various forms of obstruction to left ventricular outflow are reviewed. In children or adolescents with congenital valvular or discrete subvalvular stenosis, left heart catheterization should he performed whenever the clinical examinations indicate or suggest the possibility that severe stenosis is present. Operation is recommended in children with peak systolic pressure gradients between the left ventricle and brachial artery which exceed 50 mm. Hg or with an effective orifice less than 0.7 cm2./M2. BSA. It is now quite clear that the outlook for survival is limited in the adult with symptoms resulting from aortic stenosis, and operation is recommended when the peak systolic left ventriculararterial pressure gradient exceeds 50 mm. Hg. In many adult patients with calcific aortic stenosis, effective debridement cannot be accomplished without the destruction of valvular tissue, and excision and prosthetic replacement of at least a portion of the valve is frequently necessary. Accordingly, surgical consideration is postponed in the totally asymptomatic adult. The surgical treatment of supravalvular aortic stenosis and of idiopathic hypertrophic subaortic stenosis is usually more difficult and less effective than the surgical relief of congenital valvular or discrete subvalvular stenosis. The criteria for the selection for operation of patients with these less common forms of obstruction to left ventricular outflow are stricter than for those with the more common forms of obstruction ; the combination of severe narrowing and serious or progressive symptoms are required before operation is recommended. 'THE AMERICANJOURNALOF
CARDIOLOGY
Operation
for Left Ventricular
Outflow
Obstruction
of congenital H. T., SPENCER,F. C., BUSSE, E. F. and DAVID, F. W., JR. Cusp replacement and coronary artery perfusion in open operations on the aortic valve. Ann. Surg., 152: 494, 1960. 2. BRAUNM’ALD,E.. BROCKENBROUGH, E. C., TAIXERT, J. L., FOI.SE, J. R. and ROCKOFF, S. D. Selective left h(.art angiocardiography by the transseptal route. Am. .J. Med., 33: 213, 1962. 3. BRAUN\VILD, E., GI~LDBLATT,A., AYGEN, M. M., ROCKOFF, S. D. and MORROW, A. G. Congenital aortic stenosis. I. Clinical and hemodynamic findings in 100 patients. Circulntion, 27 : 426, 1963. 4. BRAUN~ALD, E., MORROW, A. G., CORNELL, W. P., AYGER., M. M. and HILBISH, T. F. Idiopathic hypertrophic subaortic stenosis: clinical, hemodynamic and anyiographic manifestations. .4m. 1. RAHNSON,
J. .2fed., 29: 924, 1960. 5. BRAUN~ALD. E. et al.
Clinical staff conference. Aortic stc.nosis: physiological, pathological, and clinic;ll concepts. Ann. ht. Med., 58: 494, 1963. 6. ELI.IS. E’. H. and KIRKLIN, J. W. Congenital valx-ular aortic stenosis: anatomic findings and surqical technique. J. Thor&c & Cnrdiooas. Surg.,
43: 199, 1962. 7. ELLIS, 1:. H., ONGLEY, P. A. and KIRKLIN, 3. W.
Results of surgical treatment for congenital aortic stenosis. Circulatzon, 25: 29, 1962. 8. GOLDRLATT,A., AXEN, M. M. and BRAUNWALD,E. Hemodynamic-phonocardiographic correlations of the fourth heart sound in aortic stenosis. Circulatzon, 26: 92, 1962. 9. HUFNAGEL, C. A. and
aortic stenosis.
CONRAD, P. W.
Yew England J. Med.,
Calcific 266:
72.
1962. 10. HUGENFIOL.TZ, P. G., LEES, M. M. and NADAS, A. S.
The scalar electrocardiogram, vectorcardiogram, and exercise elecrrocardiogram in the assessment
.JULY 1963
aortic stenosis.
59 Circulntion. 26: 79.
1962.
11. KAY, E. B., MENDEUOHN. D.. JR. and ZIMMERMAN, H. A. Surgical treatment of aortic valvular disease by prosthetic replacement. .l?n. J. Cnrdiol., 9: 284,
1962.
12. LEES. M. H., HAUC,K,A. J., STARKEY,G. B., NADAS,
.4. S. and GROSS. R. E. Congenital aortic stenosis: operative Indications and surgical results. Brit. Heart J., 24: 31, 1962.
McGo~N, D. C., MANKIN, H. T. and KIRKLIN, J. W. Results of open operation for acquired aortic valve disease. J. Thor& tZ Card&m. Surg., in press. 14. MORROXV.A. G., :\USTEN.W. G. and BRAUNWALD, E. The surgical treatment of calcific aortic stenosis: oprrative methods and the results of pre- and postoperative hemodynamic assessments. Ann. Surg., in press. 15. MORROM~.A. G., .\w~, \V. C and BRAUNWALD.E. Combined mitral and aortic stenosis. Brit. Hmrt
13.
J., 24: 606,
1962.
16. MORROW. A. G., GOLDBLATT, A. and BRAUN~ALD,
E. Congenital aortic stenosis. II. Surgical treatment and the results of operation. Cbmlation. 27: 450. 1963. 17. MORROW, A. G., WALDHAUSEN,I. A., PETERS:R. L.,
BLOOUWELL,R. D. and BRAUN~ALD. E. Supravalvular aortic stenosis: clinical, hemodynamic, and pathologic observations. Circulntion, 20: 1003, 1959.
18 MUUER, IV. H., JR., LITTLEFIELD,J. G. and DAMMANN..I. F., .JR. Subcoronary prosthetic replacement of the aortic valve. In: Conference on Prosthetic Valves for Cardiac Surgery, p. 493. Edited by ~~ERENDINO,K. A. Sprin$ield. Ill., 1961. Charles C Thomas.