Tetralogy of Fallot

CURRENT REVIEW

Tetralogy of Fallot Robert B. Karp, M.D., and John W. Kirklin, M.D.

T

etralogy of Fallot has been defined in various ways, but as the operative procedure for this condition has progressed, a more precise definition has evolved. In this review the term tetralogy of FaZZot denotes a congenital cardiac malformation in which a unique combination of pulmonary stenosis and ventricular septal defect occur, each with specific morphological characteristics [23]. Van Praagh and Van Praagh [49] have characterized the tetralogy as one of a group of congenital cardiac lesions resulting from underdevelopment of the distal pulmonary conus. This hypoplasia of the conus is associated with poor posterior expansion of the crista supraventricularis, leaving a junctional ventricular septal defect lying between the two divisions of the septal band and the crista. Distal conal hypoplasia is also associated with hypertrophy of those structures making up the proximal conus. This results in infundibular narrowing. The aorta may be more or less dextroposed (or overriding). T h e combination of right ventricular outflow tract obstruction and a ventricular septal defect approximately the size of the aortic annulus results in equal peak systolic pressures in both ventricles. In a clinical setting this definition of tetralogy includes, in addition, patients born with only mild infundibular stenosis in whom right ventricular outflow obstruction becomes sufficiently severe that by 2 to 4 years of age systolic pressures in both ventricles become equal. It includes patients who, although acyanotic, have morphologically typical infundibular stenosis and ventricular septal defect. Also included. are patients born with severe pulmonary outflow stenosis who, because of surgically created anastomoses or naturally developing aorto-pulmonary collaterals, acquire atresia of the pulmonary outflow tract [14, 191. From the Department of Surgery, The Medical Center, University of Alabama in Binning ham, Birmingham, Ala. 35235.

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Hypoplasia of the distal pulmonary conus is common also to a group of malformations which include some cases of aortic insufficiency with ventricular septal defect [48], ventricular septal defect with pulmonary atresia, and truncus arteriosus [49]. These malformations are not included under the term tetralogy of Fallot in this review. HISTORY

Stenson in 1671 first described the anatomy of the malformation which was to become known as tetralogy of Fallot. Fallot published his series of cases in 1888 [12]. He stressed the existence of four basic components (ventricular septal defect, pulmonary stenosis, aortic overriding, and right ventricular hypertrophy), leading to the term tetralogy. T h e work of Edwards and associates [ll], Rudolph [43], Guntheroth [ZO], Lev and Eckner [29], and others has shown that the basic anatomical picture is a combination of just the first two morphological characteristics, the aortic overriding and right ventricular hypertrophy being a consequence of the ventricular septal defect and pulmonary stenosis. Recently, Van Praagh and his associates [50] have termed the tetralogy a monology, stressing the importance of underdevelopment of the pulmonary infundibulum as the essential feature leading to the distinct Fallot anatomy. T h e diagnosis of tetralogy of Fallot received great impetus from the clinical work of Taussig in the decade 1930 to 1940 [47], and later by the angiocardiographic studies of Kjellberg and co-workers [27]. Operative treatment of tetralogy of Fallot was begun in the 1940’s by Blalock and Taussig [7], who were able to achieve significant palliation in “blue babies” using a subclavian artery-pulmonary artery anastomosis, In 1955 total open intracardiac correction of tetralogy of Fallot with cardiopulmonary bypass was begun by Lillehei and co-workers [311 in Minneapolis and Kirklin and colleagues [25] at the Mayo Clinic. At the present time, total correction with a mortality of under 10% may be offered to all patients with tetralogy. MORPHOLOGY PULMONARY STENOSIS

T h e pulmonary stenosis is a consequence of the hypoplasia of the distal pulmonary conus which results in inappropriate hypertrophy and displacement of crista supraventricularis and the muscular portions of the proximal pulmonary infundibulum. These obstructing components are the parietal band, which crosses laterally and anteriorly on the patient’s right to the ventricular free wall, and the septal band, which crosses medially to the patient’s left onto the septum and reaches VOL. 10, NO.

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the moderator band. Frequently a localized narrowing referred to as the ostium infundibulum is formed in this region. Between this and the pulmonary valve is a variable-sized infundibular chamber. These relationships are shown in Figure 1. In approximately 25% of patients the right ventricular outflow obstruction is localized at the ostium infundibulum. In another 67% combined valvular and infundibular stenosis occurs [55]. In a small percentage of patients a generalized narrowing of the infundibular chamber and pulmonary valve ring are seen. Occasionally, a localized, marked narrowing of the main pulmonary artery is found. Finally, tetralogy of Fallot may be accompanied by significant stenosis or absence of one of the main pulmonary artery branches or multiple peripheral artery stenoses. T h e severity of the resistance to the right ventricular output, that is, the severity of the pulmonary stenosis, determines the clinical status of the patient. This may be completely independent of the magnitude of the difficulty of operative correction, which is dictated by locality and type of stenosis present. VENTRICULAR SEPTAL DEFECT

T h e ventricular septal defect in tetralogy of Fallot is large and has a constant position which is slightly more anterior (or ventral) than the usual isolated ventricular septal defect (Fig. 2). The relationships of the ventricular septal defect to the aortic cusps, the bundle of His, and the tricuspid valve are of operative importance. Posteriorly a portion of the noncoronary cusp of the aortic valve

ORIFICE OF PULMONARY INFUNDIBULAR

VALVE

VALVE

RING

INFUNDIBULUM

FIG. 1. Diagrammatical representation of the anteroposterior right ventricular angiocardiogram in tetralogy of Fallot. Infundibular and valvular stenosis are present. (Modified f r o m 0. W . Kincaid, Angiocardiography in Obstructive Malformations of the R i g h t Ventricle and Pulmonary Arteries. I n M . Viamonte, Jr., and R . E . Parks [Eds.], Progress in Angiocardiography. Springfield, Ill.: T h o m a s , 1964.) 372

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FIG. 2 . Morphology o f the right ventricle in tetralogy of Fallot. T h e right ventricular free wall is opened and the orifice of the diminutive right ventricular outflow tract is visible o n the right. IS = infundibular septum; Ao = aorta; SB = septal band; VSD = ventricular septal defect; AL = anterior leaflet of tricuspid valve; SL = septal leaflet of tricuspid valve; ML = muscle of Lancisi; VS = ventricular septum; LA Div = left anterior division; RP Div = right posterior division. (From V a n Praagh and V a n Praagh [491.)

is in relation to the defect. Slightly more anteriorly, the commissure between the noncoronary and right coronary cusp is in proximity to the defect, and at operation this commissure is easily seen 2 to 4 mm. anterior to the posterior angle of the defect. T h e bundle of His is in relation to the ventricular septal defect at its posteroinferior angle, and the conduction fibers run anteriorly along the caudal or inferior margin of the defect to a point at which the muscle of Lancisi (or papillary muscle of the conus) attaches. T h e septal leaflet of the tricuspid valve forms the posteroinferior border of ventricular septal defect, but the tricuspid chordae tendineae usually do not overhang the defect to the extent seen in isolated high ventricular septal defects.

KARP AND KIRKLIN THE AORTA

Tetralogy of Fallot is not a form of transposition; that is, there is fibrous continuity between the aortic cusps and the anterior leaflet of the mitral valve. T h e aorta is rotated clockwise; thus, there is more continuity between the left coronary cusp and the mitral valve than is normally the case, and the right coronary cusp is more anterior. The rotation of the aorta and consequent overriding also may be a correlate of conal hypoplasia. Kjellberg [27] has classified the degree of overriding by lateral angiocardiograms. Increasing overriding is associated both with more anterior displacement of the aortic root and with the plane of the ventricular septum directed more posteriorly toward the left. THE VENTRICLES

T h e wall of the right ventricle is hypertrophied and the cavity of the inflow portion is moderately enlarged and heavily trabeculated. T h e left ventricle is usually of normal size or slightly small. Hypoplasia of the left ventricle actually is extremely rare [lo].

PULMONARY VASCULATURE

Patients with tetralogy of Fallot have diminished pulmonary artery blood flow and have little tendency to develop the pulmonary vascular lesions associated with pulmonary hypertension due either to a left-toright shunt or to mitral valve disease. Rich [42] and later Ferencz [13] found, however, that there was a marked tendency in 75% of patients with tetralogy of Fallot to develop thrombosis in the small pulmonary vessels. There were varying stages of vascular occlusion, thrombotic organization, and recanalization in lungs of patients both with and without anastomotic operations. Patients with tetralogy of Fallot develop a collateral circulation between the systemic and pulmonary circulation. Physiological studies show that this aorto-pulmonary collateral flow reaches the pulmonary circulation proximal to the pulmonary capillaries and may average 11% of cardiac output. In some cases this flow has been measured at 40% of systemic flow [401. ASSOCIATED ANOMALIES

Nagao and colleagues [39] have studied the incidence of anomalies associated with tetralogy of Fallot. They found atrial septa1 defect in 3.1% of their 161 patients, with an additional 14.9% having a patent foramen ovale. A persistent left superior vena cava was found in 5.6%. Nineteen percent had right aortic arch and 29% had a bicuspid pulmonary valve. Patent ductus arteriosus occurs infrequently with tetralogy. Of particular interest to the surgeon is an anomaly of the anterior 374

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descending coronary artery in which this artery takes its origin from the right coronary artery, passing from right to left across the infundibulum and supplying the anterior left ventricular myocardium. Fortunately this is a rare occurrence, but when the anomaly is present, the usual right ventriculotomy cannot be made and a tube graft across the infundibular stenosis must be used. Stenosis of a pulmonary artery branch occurred in 3 of 161 patients in Nagao’s series, but this situation has been reported in up to 25% of patients. T h e operative implications are many, and consideration of the location and degree of stenosis is important before an anastomotic operation or total correction is performed. Absence of the pulmonary valve occurs in about 3% of patients. This is associated with aneurysmal dilatation of the main pulmonary artery and a striking chest roentgenogram [9, 381. CLINICAL MANIFESTA TIONS NATURAL HISTORY

T h e clinical course is governed by the severity of the pulmonary stenosis. T h e typical patient with severe tetralogy of Fallot is born with moderate cyanosis, noted within the first month; a systolic murmur is identified, and the patient is observed to tire easily. Effort brings on hyperventilation and pallor, and within the first year or two the typical “spells” are noted. These spells are characterized by increasing cyanosis, hyperventilation, and limpness, and may terminate in syncope, convulsions, or death. In some infants with a heart that is morphologically characteristic of tetralogy of Fallot, cyanosis may be mild or absent. These patients will develop arterial desaturation within a year or two. Other infants destined to have tetralogy may be born with a large left-to-right shunt. Gasul and associates [15] have shown that such patients develop a progressively more severe pulmonary stenosis as a result of increasing hypertrophy of the infundibular structures. By age 3 or 4 years, the shunt is right-to-left and the clinical manifestations and anatomical features are those of typical tetralogy. Survival of most children with tetralogy past 1 to 2 years of age is based on the development of sufficient aorto-pulmonary collateral and polycythemia or the performance of an anastomotic operation. A few patients with only moderate pulmonary stenosis may have only moderate disability until the second or third decade, at which time polycythemia becomes severe and the effectof limited pulmonary blood flow and the right-to-left shunt begins to curtail exercise tolerance severely. Accidents of catastrophic proportion occur commonly in patients surviving the first decade. Anoxic or “blue” spells, as have been deVOL. 1 0 , NO.

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scribed here, in the untreated patient are the most common cause of death. Polycythemia leads to thrombosis. That process in the lung eventually may interfere significantly with capillary blood flow and infrequently may lead to severe compromise of lung function. Cerebral thrombosis is another complication of the polycythemia and together with the right-to-left shunt results in cerebral abscesses. Hemoptysis, a complication seen after the first decade, presumably results from the extensive aortopulmonary collateral. Anastomotic operations decrease spells as well as polycythemia while increasing exercise tolerance. Cerebral abscesses may still occur, however, and, as in the untreated patient, subacute bacterial endocarditis is a persistent worry. SYMPTOMS

T h e most frequent presenting complaint in patients with tetralogy of Fallot is cyanosis with or without spells. Some patients, however, may not have visible cyanosis and may never have had syncopal attacks. This small group does indeed have the morphology of tetralogy, together with equal ventricular pressures, but a proper balance has resulted between right-to-left and left-to-right shunting to allow fairly adequate day-today existence. Spells are said to occur as a result of contraction of the infundibular muscle. Guntheroth and co-workers [21] state that hyperpnea is the common denominator in a cycle which results in an increased right-to-left shunt and decreased pulmonary blood flow. Arterial pC0, increases, PO, decreases, and pH decreases, leading finally to syncope. Squatting occurs very frequently and is a predominant feature of tetralogy of Fallot. T h e ameliorative effect of squatting is due to a decrease in right-to-left shunt. Two mechanisms in combination effect a change in pressure gradient across the ventricular septa1 defect. Blood flow to the lower extremities is reduced and thus, due to lessening of venous return, right ventricular pressure decreases. Also, left ventricular pressure increases secondary to an elevation of peripheral resistance. Symptoms related to the complications of the malformation may predominate in later years. Hemoptysis, hemiplegia, or, in the third or fourth decade, congestive heart failure may be noted. SIGNS

Patients with tetralogy of Fallot are cyanotic to a variable degree. Clubbing is present. Excess sweating and an increased incidence of acne have been noted. A systolic murmur is generally present. T h e intensity of the murmur is related to the blood flow into the main pulmonary artery. Thus, absence of a murmur or a soft murmur without a thrill signifies severe pulmonary stenosis and a small pulmonary blood flow. 376

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Continuous murmurs may occur with tetralogy, and this suggests peripheral pulmonary stenosis, pulmonary valve insufficiency, a patent Blalock or Potts shunt, or extensive aorto-pulmonary collateral. Classically, the second sound at the base is single. CHEST ROENTGENOGRAM

T h e PA chest film is one of the most valuable studies in the diagnosis of tetralogy of Fallot. T h e size of the ascending aorta and position of the arch, the contour of the ventricular mass, and the degree and pattern of the pulmonary vascularity are particularly important (Fig. 3).

A

B FIG. 3. Posteroanterior and lateral chest roentgenograms in tetralogy of Fallot. The apex is upturned as a result of right ventricular enlargement. The main pulmonary artery segment is small, giving a concave left-heart border. The pulmonary vascularity is diminished.

KAKP AND KIRKLIN ELECTROCARDIOGRAM

T h e pattern of right ventricular hypertrophy is typically found in patients with tetralogy of Fallot. T h e unipolar leads show a tall R wave in Lead V,, notched on the upstroke. There is a sharp transition between V, and V,, with diminished R waves and deep S waves in the left precordial leads.

LABORATORY STUDIES

Chronic mild acidosis may be present in patients with severe tetralogy of Fallot. During acute hypoxic spells pH decreases, and although hyperventilation is present, arterial pC0, is normal or slightly elevated due to low pulmonary blood flow [18]. Arterial desaturation leads to polycythemia. However, iron may be deficient in the diet of many small infants so that a relative anemia exists. In the presence of an increased hematocrit and red blood cell count, there may be a reduction of mean corpuscular hemoglobin concentration and mean corpuscular volume, leading to a decreased oxygen-carrying capacity [44]. PHYSIOLOGICAL STUDIES VENTRICULAR SEPTAL DEFECT FLOW

T h e right-to-left shunt across the ventricular septal defect has been shown by Levin and his colleagues [30] to occur in two phases of the cardiac cycle and at two sites. Early during ventricular systole, blood flows from the right ventricle into the dextroposed aorta. During so-called isovolumic relaxation (early diastole), blood flows from the right ventricle into the left ventricle. These flow relationships are a result of changing intraventricular pressure relationships and asynchronous ventricular contraction and relaxation. Levin has also demonstrated a left-to-right shunt through the defect during middiastole. Arterial PO, has been shown to fall with exercise or during quiet standing [32]. Arterial PO, is increased by squatting. As mentioned previously, the arterial PO, depends on the direction and magnitude of ventricular septal defect flow, which in turn is based to some extent on resistance to emptying of each ventricle. COLLATERAL FLOW

Aorto-pulmonary collateral flow may vary from 5 to 40% of total cardiac output. T h e magnitude of naturally occurring collateral may significantly ameliorate the clinical syndrome. Of course, high-flow surgical shunts such as the Potts anastomosis may lead also to significant pulmonary vascular disease, and some patients are inoperable because of high pulmonary vascular resistance. 378

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INDICATIONS FOR OPERATION

T h e indications for operation in tetralogy of Fallot are deduced from the history of the lesion and the risks and results of operative intervention. Complete intracardiac repair is associated today with low hospital mortality, and late death after repair is uncommon. T h e symptomatic and hemodynamic results of operation are generally among the most satisfying in surgery. We have generally advised open intracardiac repair for all patients 5 years of age or older with tetralogy with or without symptoms. Preliminary anastomotic operations are not necessary in patients more than 5 years old. For patients 2 to 5 years of age primary intracardiac correction has been proposed [8, 33, 541. Woodson and co-workers [54] noted a lower mortality and fewer complications from primary repair than from anastomotic procedures in this age group. However, in our experience and that of others [5, 261 the complications of bypass, the incidence of heart block, the incidence of recurrent ventricular septa1 defect, and the operative mortality are higher in patients less than 5 years old. T h e occurrence of hypoxic spells is the compelling indication for operation for tetralogy of Fallot. I n patients under the optimal age for intracardiac repair, an anastomotic operation is advised. In children over 1 year of age a Blalock-Taussig procedure is done on the side opposite the aortic arch. Infants under 1 year are explored on the right side; if the subclavian artery is not of adequate size for anastomosis to the pulmonary artery, an ascending aorta-right pulmonary artery anastomosis is done. CONTRAINDICATIONS

If less than half of the pulmonary vascular bed is anatomically or functionally available for blood flow, complete repair should not be done. Absence of the left pulmonary artery occasionally occurs in tetralogy, and if documented by late-filming aortography [4], operation is usually contraindicated. Some patients suffer multiple thromboses of the pulmonary arteries, and if the pulmonary vasculature is seriously diminished in this manner, operation is contraindicated. Kinking and subsequent complete distal occlusion of a pulmonary artery subsequent to an anastomotic operation may also render the patient inoperable. Pulmonary hypertension occurs rarely following a systemic-pulmonary artery anastomosis, and if the ratio of pulmonary resistance to systemic resistance is greater than 0.85, complete repair is not indicated. Small pulmonary arteries have not been a factor in deciding against complete correction. Infrequently, in patients over 5 years the left venVOL. 10, NO.

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tricle may be abnormally small such that left ventricular performance after repair may be inadequate. In these few patients a preliminary anastomotic operation should be done [lo]. DESCRIPTION OF OPERATION

Intracardiac repair of tetralogy of Fallot consists basically of relieving the pulmonary stenosis and closing the ventricular septal defect. Operation is performed using a disc oxygenator, moderate hypothermia (30°C.), and intermittent cardiac asystole. A vent is placed in the left ventricle. We prefer a transverse or oblique right ventriculotomy appropriate to the course of the right coronary artery and placed just caudal to the aortic root and just upstream to the ostium infundibulum. This gives good exposure of the ventricular septal defect and satisfactory approach to the mobilization and resection of the pulmonary stenosis with less depression, compared to a vertical incision, of the right ventricular myocardial function [I 61. T h e septal band, parietal band, and crista are identified and separately mobilized, and redundant portions are excised (Fig. 4).This generally relieves the stenosis; however, the ante-

FIG. 4 . Relief of pulmonary stenosis. (A) Transverse ventriculotomy. (B) Mobilization and resection of septal band, parietal band, and portions of ventricular free wall and crista. (C) Infundibular stenosis relieved and ventricular septal defect exposed. (From J . W . Kirklin [231. Reproduced from M . Viamonte, Jr., and R . E. Parks [Eds.], Progress in Angiocardiography. Springfield, 111.: Thomas, 1964.)

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rior right ventricular free wall and fibrous crest of the crista are shaved and resected if necessary. If pulmonic valvular stenosis is present, it is generally approached from below through the valve ring. If this is not satisfactory, a separate arteriotomy of the pulmonary artery is made and the commissures are separated under direct vision. T h e ventricular septal defect is closed using a Dacron patch cut slightly smaller than the defect so as to pull the crista dorsally and away from the pulmonary outflow tract. Generally, a continuous suture is used, interrupted at zones of transition where tissue planes change. Special care must be taken at the posteroinferior border of the defect where the conduction bundle running anteriorly traverses the rim of the defect. Stitches are taken 4 to 5 mm. from the rim and the suture is continued anteriorly in this fashion. Another suture is begun at the base of the septal leaflet of the tricuspid valve and continued cephalad, avoiding the aortic valve cusps and continuing onto the right ventricular myocardium and then to the crista. T h e septal or anterior rim of the defect is closed last (Fig. 5). Pressures in the right and left ventricle must be measured after discontinuing bypass but before removing the perfusion cannulas. T h e need for an outflow tract patch of pericardium is dictated by pressure relationships of the right ventricle and left ventricle and by the corresponding right atrial and left atrial pressure ratios. If the RV/LV pressure ratio is 0.8 or less and cardiac output is good, a patch is not used. If the ratio is higher, a patch probably will be needed except when cardiac output seems good and the RA/LA ratio is less than 1, suggesting that right ventricular performance is not the limiting factor. An outflow patch is used in about 20% of patients. This frequency has diminished in the past few years [26] coincident with greater familiarity with the anatomy and technical details of the operation and with concern for the possible long-term effects of pulmonary valve insufficiency. As an alternative in the reconstruction of a narrow outflow tract, homograft aortic valves have been used [52]. Widening of the outflow tract is accomplished and competence of the pulmonary valve area is maintained. This may be particularly useful in older children or young adults in whom acquired near atresia exists. Functioning Blalock shunts are ligated immediately after initiation of cardiopulmonary bypass. Closure of a Potts anastomosis is done through the left pulmonary artery under circulatory arrest after deep hypothermia is achieved by the pump oxygenator [24]. RESULTS OF OPERA T I O N HOSPITAL MORTALITY

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FIG. 5. Closure of ventricular septa1 defect. T h e first stitch is taken at the posteroinferior angle of the defect, 4 to 5 mm. away from the rim. T h e suture is continued anteriorly and then posterosuperiorly from this point. (From J . W . Kirklin [231. Reproduced from M . Viamonte, Jr., and R. E. Parks rEds.1, Progress in Angiocardiography.Springfield, Ill.: Thomas, 1964.)

With the passage of time, experience with the precise operative technique has been gained and is reflected in the decreasing mortality figures. T h e University of Alabama experience from 1967 to 1968 is shown in Table 2. Following are several factors that may influence operative mortality. Previous Operation. Certainly the results of Malm [351, Shumway [46], Vathayanon [51], Kirklin [26], and their colleagues suggest that children who have had a previous Blalock-Taussig shunt do as well as those who have not had a previous operation. However, Gold382

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TABLE 1. RESULTS OF OPEN INTRACARDIAC CORRECTION OF TETRALOGY OF FALLOT

Author Poulsen et al. [411 wolf et al. 1531 Goldman et al. U71

Dates 1956-1962 1956-1962 1957-1966

No. of Patients 34 146 188

Klinner and Zenker [281 Bjernulf et al. [61 Azar et al. [31

1959-1963

178

1959-1963 1959-1968

56 200

1960-1 962 1960-1966 1960-1964

41 100 337

1960-1964 1960-1965

44 100

1963-1968 1965-1968

121 62

Malm et al. [34, 351 Kirklin et a1 [261 Shumway et al. 1461 Barnard and Schrire [51 Hawe et al. [221 Vathayanon [511

Hospital Deaths (70) 65 29 39 (1957-1962) 20 (1963-1966) (31-13) 25

Patients with Previous Operations

30 13 (43-0) 0 7 11 (15-7)

(%)

74 66 61

.... 28 25 62 69 51

12

39 19

3

....

0

1.6

19

Series are listed in chronological order. Percent in parentheses indicates range of yearly mortality, the lower number being the most recent yearly experience.

man and co-workers [17] noted that the mortality was lower in their patients who had not required previous palliative operation, and Meyer and associates [36] report a 13% mortality in 54 patients with previous operations, 22 of whom had undergone a previous Potts anastomosis. We would agree with Wolf and his colleagues [53] that previous end-toend shunts, Potts anastomoses, and bilateral complex anastomoses are associated with a higher mortality at complete correction. Right Ventricular Outpow Patch. In our series the use of a right ventricular outflow tract patch has decreased to a rather constant figure of 20% in recent years. Several studies [3, 17, 531 suggest that the mortality is higher in patients who have an outflow tract patch than in patients in whom no patch was used. Wolf and colleagues [53] reported that with patches the mortality was 49%, compared to 24% without. Yet Hawe and his associates 1221report a 3% mortality in a recent group of 121 patients in whom an outflow tract patch was used in 36%. Although the mortality distribution was not indicated, obviously it was low in both groups. Our experience is similar [26]. Residual Right Ventricular Hypertension. Although earlier pubVOL.

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KARP AND KIRKLIN TABLE 2. INTRACARDIAC REPAIR OF TETRALOGY OF FALLOT (1967-1968)

Hospital Deaths Operation Primary operation Previous Blalock operation Previous Potts operation Multiple previous operations Adult with heart failure Total

No. of Repairs 29 24 5 4 1 63

No. I 1

2 1 1

6

% of

Total 3.4 4.2 40 25

100

9.5

SOURCE: From J. W. Kirklin and R. B. Karp, The Tetralogy of Fallot from a Surgical

Viewpoint. Philadelphia: Saunders, 1970.

lications suggested that there was a relation between hospital mortality and the RV/LV peak-pressure ratio immediately following repair, more recent experience is not so convincing. It now appears that if the operative procedure and postoperative care are properly done, RV/LV pressure ratios of 0.75 to 0.80 can be accepted with no increase in hospital mortality. T h e interpretation of the postrepair peak-pressure ratio must take into account the type of outflow tract anatomy, the precision of the infundibular resection, and the status of the cardiac output and atrial pressure relationships [23]. PERMANENT HEART BLOCK

Complete heart block occurs in 1% or less of patients who have intracardiac correction. T h e incidence of block seems higher in reports of patients who have complete correction before the age of 5 years. In the series of McMillan and associates [331,4of 14 young children developed heart block; however, both Woodson and colleagues [54] and Dobell and his co-workers [8] more recently report no instances of heart block in each of their series of young children submitted to total correc tion. RESIDUAL VENTRICULAR SEPTAL DEFECT

T h e exact incidence of residual left-to-right shunt at the ventricular level late postoperatively is unknown. I n 34 patients studied for various reasons 1 to 9 years postoperatively at the Mayo Clinic, there were no residual shunts [l]. Malm and associates [35]reported 9 patients out of 64 recatheterized postoperatively to have left-to-right shunts. In 8 of the 9 the shunt was small. A residual shunt occurred in the presence of multiple muscular defects, common ventricle and supracristal defects (most of which are not usually associated with tetralogy of Fallot). T h e usual site of inadequate closure is at the posteroinferior aspect of the defect. Placement of the initial sutures in a precise manner is doubly important here; the conduction bundle must be avoided, but the usual site of leakage must be closed. 384

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LAI'E HEMODYNAMIC AND MORPHOLOGICAL RESULTS

Right ventricular performance is adequate late after total correction. In patients studied by Shah and Kidd [45] 1 to 5 years postoperatively, right atrial and right ventricular pressures were normal or slightly elevated at rest and were unaltered by exercise. Right atrial pressure is only slightly elevated in patients with fesidual pulmonary valve incompetence. No abnormalities of left ventricular performance have been noted postoperatively. Angiocardiograms taken late after complete repair generally show rather normal-appearing pulmonary outflow tract and pulmonary arteries. T h e right ventricle enlarges, particularly in the presence of pulmonary valve incompetence. A fullness in the outflow tract may be present in half of the cases in which a pericardial patch was used, but progressive aneurysmal dilatation has not been a problem in our patients. Anderson and his colleagues [Z] found that the usual cause of late enlargement of the outflow tract was a residual left-to-right shunt. SYMPTOMATIC RESULTS

Late postoperatively, 93% of patients have been found to be completely asymptomatic [26]. Over a 10-year period there have been no adverse effects of moderate residual outflow gradients or pulmonary valve insufficiency.

REFERENCES 1. Albertal, G., Swan, H. J. C., and Kirklin, J. W. Hemodynamic studies two weeks to six years after repair of tetralogy of Fallot. Circulation 29:583, 1964. 2. Anderson, I. M., Newman, C. G. H., and Urquhart, W. Fallot's tetralogy: Some radiological and other findings in the first few years after total correction. Brit. J. Radiol. 38:81, 1965. 3. Azar, H., Hardesty, R. L., Pontius, R. F., Zuberbuhler, J. R., and Bahnson, H. T. A review of total correction in 200 cases of tetralogy of Fallot. Arch. Surg. (Chicago) 99:281, 1969. 4. Barcia, A. Personal communication, 1969. 5. Barnard, C. N., and Schrire, V. The surgical approach to tetralogy of Fallot. S. Afr. Med. J. 40:330, 1966. 6. Bjernulf, A., Cullhed, I., Hallen, A., and Michaelsson, M. Primary and late results of open correction of Fallot's disease. Acta Med. Scand. 184:89, 1968. 7. Blalock, A., and Taussig, H. B. The surgical treatment of malformations of the heart in which there is pulmonary stenosis or pulmonary atresia. J.A.M.A. 128:189, 1945. 8. Dobell, A. R. C., Charrette, E. P., and Chughtai, M. S. Correction of tetralogy of Fallot in the young child. J. Thorac. Cardiovasc. Surg. 55:70, 1968. 9. Durnin, R. E., Willner, R., Virmani, S., Lawrence, T. Y., and Fyler, D. C. Pulmonary regurgitation with ventricular septa1 defect and pulmonic stenosis: Tetralogy of Fallot variant. Arner. J. Roentgen. 106:42, 1969. 10. Ebert, P. A., and Sabiston, D. C., Jr. Surgical management of the tetralogy of Fallot: Influence of a previous systemic-pulmonary anastomosis on the results of open correction. Ann. Surg. 165:806, 1967. VOL. 10, NO.

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