Symposium on Pediatric Cardiology

Cyanotic Congenital Heart Defects with Increased Pulmonary Blood Flow

Isamu Kawabori, M.D.*

After the patient is determined to be cyanotic and the chest x-ray evaluation is consistent with increased blood flow, the differential diagnoses in the flow diagram (see p. 760) bring together a group of congenital heart defects that form the basis of this article. These patients have in common anatomy and physiology such that there is increased pulmonary blood flow associated with cyanosis.

TRANSPOSITION OF THE GREAT ARTERIES Transposition of the great arteries is found in 5 per cent of all patients with a congenital heart defect. As the name implies there is a reversal of the origins of the aorta and pulmonary artery so that the aorta arises anteriorly from the right ventricle, with the level of the aortic valve at a higher level than the pulmonary artery which arises from the left ventricle, with the pulmonary artery being posterior to the aorta and the pulmonary valve level inferior to the aortic valve level. Patients with transposition of the great arteries may have a variety of associated cardiac defects. This is the most common cyanotic congenital heart defect noted at birth and one that can be greatly· helped with early intervention, both medical and surgical. ANATOMY AND PHYSIOLOGY. The patient with uncomplicated transposition of the great arteries (one with no associated defects) presents very early with marked cyanosis and tachypnea because of a lack of adequate systemic venous ·and pulmonary venous mixing (bidirectional shunting) between the parallel circulations, and congestive heart failure because of pulmonary overcirculation and the volume overwork of the heart. These patients survive for a while on the basis of a patent foramen ovale and!or small patent ductus arteriosus. The presence of additional defects or a significant atrial septal defect! patent ductus arteriosus usually allows varying degrees of mixing "Assistant Professor of Pediatric Cardiology, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington

Pediatric Clinics of North America - Vol. 25, No.4, November 1978

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of the parallel circulations so that the infant may be moderately cyanotic to almost normal in coloring. While admixing lesions such as an atrial septal defect or patent ductus arteriosus do not complicate reparative surgery, a significant ventricular septal defect, pulmonary stenosis, or infundibular pulmonary stenosis can certainly complicate the ultimate surgical repair, although these "complicated" patients with a good balance of pressure and flow may have the best coloring and may not require early surgery. Even with significant additional defects that should allow for good mixing of the parallel circulations, this may not occur in the newborn infant until the pulmonary vascular resistance falls to more normal levels. The most readily reparable form of transposition of the great arteries clinically presents early with cyanosis and tachypnea because of the lack of mixing of the parallel systemic and pulmonary circulations. The pulmonary vessels are engorged. Through an adequate sized ventricular or atrial septal defect there is good bidirectional mixing. Through the patent ductus arteriosus the shunt is primarily from the .systemic to the pulmonary circulations, with the pulmonary to systemic shunt occurring through a stretched patent foramen ovale. In a patient with transposition of the great arteries, ventricular septal defect, and pulmonary stenosis (infundibular or valvular), the balance between the resistance from the pulmonary stenosis to flow into the lungs and across the ventricular septal defect into the systemic circuit is sometimes remarkable, allowing a number of years for medical management before surgery is required. The patient with transposition of the great arteries is at risk of developing pulmonary vascular changes earlier than what would be expected in acyanotic patients. This is true even in patients whose mixing is through an atrial septal defect, which should allow for normal or nearly normal pressures in the pulmonary circuit. Significant pulmonary vascular changes add increased risks to the reparative surgery, or even with operative survival limit function or longevity or both postoperatively. CLINICAL FINDINGS. Of interest is that there is a preponderance of males who have this abnormality. In the patient who has uncomplicated transposition of the great arteries, there is significant cyanosis, tachypnea, and early onset of congestive heart failure. In patients with "uncomplicated" transposition of the great arteries, these symptoms may progress rapidly to metabolic acidosis and death, and aggressive medical management is needed. Those patients whose transposition of the great arteries is complicated by additional defects will present with lesser cyanosis or even very little cyanosis if the mixing is good. These patients tend to manifest tachypnea and congestive heart failure somewhat later and have a later "onset" of cyanosis, but present ultimately a more difficult surgical problem at the time of repair. Patent ductus arteriosus and atrial septal defect do not complicate surgery. The clinical findings are very much dependent upon the age of the infant at the time of evaluation and the presence or absence of additional cardiac abnormalities. In the patient with uncomplicated trans-

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position of the great arteries early in the postnatal course, marked cyanosis (which unless marked may be difficult to delineate by "eyeball oximetry") and tachypena may occur. This child will go on to develop congestive heart failure. There may be no murmurs and the second heart sound, although accentuated in intensity, can be easily misjudged as normal in the young infant. Gallop sounds and hepatomegaly will be present only with congestive heart failure. In the newborn period the elevated hematocrits do not exceed the usual norms. Death from hypoxia and secondary metabolic acidosis can occur in a matter of a few days. The infant with transposition of the great arteries and additional cardiac defects can have surprisingly close to normal coloring if the "balance" of the lesions is such that there is good pulmonary blood flow and good admixture of the pulmonary venous and systemic venous blood. Although some degree of cyanosis is usually perceived and most will develop congestive heart failure, there are occasional patients whose balance of lesions is such that they have good oxygenation and no congestive heart failure. All of these patients, if not referred because of cyanosis or congestive heart failure, are referred because of the presence of murmurs. The character of the murmurs will depend on the associated lesions and the patient's physiology. In the patient with transposition of the great arteries, the second heart sound is generally accentuated or louder than normal, which represents the aortic closure because of the location of the aorta directly behind the sternum. In patients with transposition of the great arteries and associated cardiac lesions the typical auscultatory findings for these associated lesions are usually present if the pulmonary vascular resistance is normal or relatively normal. Diastolic inflow murmurs may be present just as in acyanotic patients with pulmonary overcirculation. The presence of pulmonary vascular disease may diminish murmurs associated with the defect(s) found in transposition of the great arteries. Outside of the newborn period, cyanosis and clubbing, murmurs of atrial or ventricular septal defect, pulmonary stenosis, or patent ductus arteriosus, if also present, are heard, the presence or absence of thrills depending only upon the intensity of the murmur; diastolic inflow murmurs can be heard in approprate cases, mild dyspnea is present, and exercise tolerance is not as good as in other youngsters. No intellectual deficit occurs because of the hypoxemia. Total anomalous pulmonary venous return (TAPVR), truncus arteriosus, single ventricle, or hypoplastic left heart syndrome need to be considered. TAPVR may be distinguished from transposition of the great arteries by the x-ray appearance and/or ECG, and truncus arteriosus by chest x-ray film if higher than normal level of right and left pulmonary artery origins are present. The ECG may help to distinguish the single ventricle and hypoplastic left heart syndrome from transposition of the great arteries. CHEST X-RAY FILMS. Characteristically, the patient with typical transposition of the great arteries very early in the clinical course (a few hours of age) may have no cardiomegaly and no apparent in-

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Figure 1. The "egg on side" appearance of the cardiac silhouette, with narrow waist, increased pulmonary blood flow, and cardiomegaly, is seen in a patient with transposition of the great arteries.

creased pulmonary blood flow, but by a few days of age has an enlarged heart because of the volume work done and congestive heart failure with increased pulmonary blood flow. The characteristic "egg on side" appearance of the heart and narrow waist are due to the presence of a large right atrium, a radiologically "absent" thymus, and great vessels that are in an anteroposterior positional relationship (Fig. 1). Without the stress of hypoxia shrinking the thymus in the newborn period, many of the radiologic clues to the presence of this entity are obscured. Because of the possible associated cardiac defects, it is possible to have radiologically observed decrease in pulmonary blood flow. ELECTROCARDIOGRAM. The ECG in the typical case of transposition of the great arteries shows right axis deviation and right ventricular hypertrophy (Fig. 2). In the immediate newborn period the range of normal is sufficiently broad that the right ventricular hypertrophy may not be diagnosed by strict application of the voltage criteria. Right axis deviation is a frequent concomitant finding. If there is excessive pressure work being done by the left ventricle (e.g., because of a ventricular septal defect, pulmonary stenosis, or both, or a patent ductus arteriosus), the ECG will show evidence of abnormal (for patients with transposition of the great arteries) left ventricular voltages. Depending upon the severity there may be combined ventricular hypertrophy with right ventricular dominance, combined ventricular hypertrophy with left ventricular dominance or, rarely, left ventricular hypertrophy. Left ventricular dominance on the ECG usually indicates the presence of complicating anatomic factors such as severe pulmonary stenosis, or in the absence of pulmonary stenosis, the presence of pulmonary vascular disease. ECHOCARDIOGRAM. In patients with transposition of the great arteries the differences in the relationships of the great vessels may be detected by the echo. Reversal of the systolic time intervals is also helpful to identify the great vessels. If the ductus is patent, the pulsed Doppler can determine in which of the great vessels there is the continuous ductal flow, and this identifies the vessel as the pulmonary artery. During the neonatal period almost all patients have a patent

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Figure 2. A, No definite abnormalities on this electrocardiogram from a newborn infant with transposition of the great arteries. B, In this characteristic electrocardiogram from a patient with uncomplicated transposition of the great arteries, note the right axis deviation, right ventricular hypertrophy, and right atrial hypertrophy. This patient was three months of age.

ductus arteriosus (that may be clinically silent) which is diagnosable through the use of the pulsed Doppler to identify the pulmonary artery. Associated defects may also be identified. CARDIAC CATHETERIZATION. This is most helpful in making the diagnosis, determining the presence of concomitant defects, and in evaluating the pulmonary artery pressures. The balloon atrioseptostomy can be a life-saving palliative procedure. MANAGEMENT. Post-catheterization management is dependent upon the anatomy and physiology of each patient. In general, congestive heart failure and cyanosis are continuing problems, although not invariably so. The newborn infant whose pulmonary vascular resis-

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tance is still high may not respond to an adequate septostomy dramatically, but will continue to improve in coloring as the pulmonary vascular resistance continues to drop postnatally. Lanoxin is a part of the medical management for most patients. Polycythemia may improve in some; in others with little systemic hypoxemia the hematocrit may be only moderately elevated. The usual degree of hypoxemia for the patient may be judged from the hematocrit or hemoglobin if the patient is not relatively anemic. Increasing polycythemia to high levels should prompt surgical consideration. We reserve the Blalock-Hanlon (surgical atrioseptectomy) procedure for those patients in whom the balloon septostomy was unsuccessful as the initial procedure. Late "failure" of the septostomy is not uncommon, i.e., the patient becomes significantly cyanotic. Following either the Blalock-Hanlon or interatrial baffle repair there may be problems with conduction and arrhythmias. Nationally, of the reported arrhythmias, the most significant are atrioventricular blocks and impaired sinoatrial node function, leading to either atrioventricular junctional (high bundle of His) rhythm or sick sinus syndrome of alternating tachyarrhythmia and bradyarrhythmia, respectively. One significant anatomic dysfunction reported is obstruction of either superior or inferior vena caval or drainage into the main portion of the surgically created systemic venous return atrium. This may manifest itself as a caval syndrome with noticeable weight gain, edema, and observable prominence of the superficial venous collateral circulation. This usually necessitates a repeat cardiac catheterization and re-operation. Significant obstruction to pulmonary venous return has a poor immediate postoperative prognosis. Baffle "leaks" (in which the baffle material was not sewed tightly enough to the atrial wall) can allow shunting to occur at the atrial level in either direction. Depending upon the surgeon's preference, the coronary sinus may be included in the systemic venous return atrium (the normal physiologic finding) or in the pulmonary venous return atrium (making for a small right to left shunt). In our experience in following these children we have not yet noted tricuspid (systemic atrioventricular) valvular malfunction of any hemodynamic consequence. These problems discussed may be significant and may require treatment as well as limitation of activities. The ultimate prognosis is yet to be determined for these patients. In the successfully operated patient with transposition of the great arteries the general clinical outlook is good. Summary Patients with "uncomplicated" transposition of the great arteries come to attention shortly after birth because of the cyanosis or congestive heart failure; early development of severe cyanosis, cardiomegaly, pulmonary overcirculation and right ventricular hypertrophy on the ECG suggest transposition of the great arteries. Additional cardiac defects are common and these murmurs can be identified through auscultation; S2 is loud. Patients with "complicated" transposition of the

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great arteries may have delayed development of symptoms. Balloon atrioseptostomy may be life-saving. Pulmonary vascular disease may occur very early. Reparative surgery may be performed in infancy with a high success rate for patients with uncomplicated transposition of the great arteries.

TOTAL ANOMALOUS PULMONARY VENOUS RETURN This abnormality occurs in 1 per cent of congenital heart defects and may be defined simply as having all pulmonary veins entering the right atrium or one of its tributaries. An atrial septal defect is an integral part of this abnormality. Prognosis depends upon the anatomy. Three "levels" of entry into the systemic venous return atrium are involved: supracardiac TAPVR via (ultimately) the superior vena cava, cardiac TAPVR commonly via the coronary sinus, and less commonly directly to the right atrium, and infradiaphragmatic usually via the portal vein or less commonly to the ductus venosus. It is important to differentiate this condition from other problems because corrective surgery is possible. ANATOMY AND PHYSIOLOGY. The supracardiac and cardiac TAPVR are not usually obstructed, and the patient may not be symptomatic in the newborn period. Some patients may, however, come to attention at several months of age with symptoms. Pulmonary overcirculation and cardiomegaly are seen. Because of the high saturation of the admixed blood, cyanosis is generally not seen. The infradiaphragmatic TAPVR is usually obstructed, and the patient is very symptomatic. The patient with this type of obstructed TAPVR is recognized as being in trouble early in the postnatal course. Differentiating this patient from one with severe idiopathic respiratory distress syndrome may be clinically difficult at times. The pulmonary hypertension due to increased pulmonary venous return is severe. The heart may be relatively normal in size because the problem is one of pressure work rather than volume work, and there may be massive hepatomegaly, marked hypoxia and acidosis, and active and passive congestion of the lungs on the chest x-ray film. CLINICAL FINDINGS. Patients with nonobstructed supracardiac and cardiac TAPVR make up 80 per cent of patients with TAPVR if the mixed types are included. Without pulmonary venous obstruction, these children, except for the clinical findings of mild cyanosis, behave very much like the patient with an atrial septal defect. They have relatively good exercise tolerance. Patients with obstructed TAPVR, most of whom are of the infradiaphragmatic type, conversely are symptomatic early. Severe congestive heart failure, dyspnea, and hypoxia are common findings. The clinical findings divide patients into two groups: those without pulmonary venous obstruction, and those with pulmonary venous obstruction. Many of the infants with TAPVR without angiographically proven obstruction are believed to be normal, but in the first several months of life develop tachypnea, become irritable, develop feeding

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problems, and fail to gain weight adequately. The cyanosis becomes clinically more apparent and increased with crying or activity. Recurrent pulmonary infections and congestive heart failure may occur by six months of age. Patients have high pulmonary artery pressures. However, there are those with TAPVR who behave in every respect like the patient with a large atrial septal defect except for the presence of cyanosis, clubbing, and polycythemia. These patients have soft systolic ejection murmurs, a diastolic inflow murmur at the tricuspid valve area, and a widely split second heart sound with normal intensity of pulmonic closure. The patients with TAPVR with obstruction constitute a high risk group. They have significant dyspnea, cyanosis, and congestive heart failure. There may be poor peripheral perfusion, marked hepatomegaly, an accentuated second heart sound, as well as third and fourth heart sounds ("quadruple rhythm"). The condition of these patients may deteriorate rapidly due to hypoxia, severe congestive heart failure, and acidosis. Other cardiac defects that should be considered are hypoplastic

Figure 3. A, This newborn infant with obstructed total anomalous pulmonary venous return was admitted as having respiratory distress syndrome (note the umbilical artery catheter). Marked pulmonary venous engorgement progressed as noted on the x-ray at the far right. The diagnosis was made at cardiac catheterization. B, The older infant, or in this case, a preschool child, with nonobstructed supracardiac total anomalous pulmonary venous return shows the classic "snowman" appearance, and has a large right atrium and increased pulmonary blood flow . Significant retrosternal fullness on the lateral view indicates right ventricular enlargement.

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left heart syndrome, transposition of the great arteries, truncus arteriosus, and single ventricle. The patient with transposition of the great arteries should be differentiated by chest x-ray film; patients with truncus arteriosus, single ventricle, and hypoplastic left heart syndrome may be distinguished by electrocardiogram. Cardiac catheterization will differentiate all of the above defects. CHEST X-RAY FILMS. Findings from chest x-ray films tend to fall into two categories also. Those patients with unobstructed pulmonary venous return have both increased pulmonary blood flow and a large cardiac silhouette, especially of the right atrium, right ventricle, and pulmonary artery. Intracardiac TAPVR without obstruction resembles an x-ray film of an atrial septal defect. Supracardiac TAPVR characteristically has a "snowman" or "figure-of-eight" configuration formed by the heart (lower portion of the snowman), and the ascending common pulmonary vein on the left of the mediastinum and a greatly dilated superior vena cava on the right of the mediastinum (forming the upper portion of the snowman). However, this usually is not evident until about six months of age or older. It may, at times, be somewhat subtle. The left atrium and ventricle are not enlarged (Fig. 3). The patient with obstructed pulmonary venous return has markedly increased pulmonary vascular markings with pulmonary venous engorgement and pulmonary edema. The heart size may initially be within normalliInits because there is no volume load (Fig. 3) ELECTROCARDIOGRAM. Right axis deviation and right ventricular hype trophy are invariably present, and right atrial hypertrophy is more often seen in those patients without obstruction. The ECG for a patient with unobstructed TAPVR is similar to that of a patient with an secundum atrial septal defect, since except for cyanosis, they are quite siInilar in physiology (Fig. 4). ECHOCARDIOGRAM. The echo will show a large right ventricle, paradoxical septal motion, small left atrium and ventricle, and aortic valve ring. If the common pulmonary vein is present behind the left atrium, it sometimes can be found, but care mustbe exercised since a line is often seen in the left atrial echo in normal neonates. Doppler echocardiography is very good to assess the flow pattern in this echo space, and the pulmonary venous flow may be followed. The Doppler will then give information as to whether the line in the atrium constitutes a wall of the pulmonary vein or an artifact. CARDIAC CATHETERIZATION. The cardiac catheterization is diagnostic and will demonstrate the anatomy, the level of the pulmonary artery pressure, pUlmonary vascular resistance, and site of obstruction, if any. MANAGEMENT. Preoperative management of the patient with TAPVR involves handling the congestive heart failure, failure to thrive, and any respiratory infections that occur. If these problems are present, surgical intervention is best at any age. Some patients with TAPVR without obstruction behave siInilarly to the patient with an atrial septal defect. Preoperative management in the infant with obstructed veins before referral to a center consists of rapid evaluation of the critically sick newborn infant, arrival at a tentative diagnosis, and

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Figure 4. A, Electrocardiogram from the patient in Figure 4A. shows right axis deviation but does not meet the voltage criteria in the newborn infant for right ventricular hypertrophy; however, the inverted T-wave in V. (beyond 1 or 2 days of age) and abnormal T-axis defined this electrocardiogram as being abnormal. B, An electrocardiogram from the patient in Figure 4B. shows right axis deviation and right ventricular hypertrophy.

stabilization of the cardiovascular status while transferring the patient. Time is of utmost consideration since congestive heart failure and hypoxia are severe problems that may lead to rapid deterioration with metabolic acidosis and death. Postoperatively the management should be fairly routine if no additional cardiac defects were present. Summary

Patients with obstructed TAPVR come to attention early and require urgent treatment (surgical); these patients may have congestive

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heart failure with a small heart on chest x-ray film. Patients with unobstructed T APVR may be only mildly cyanotic and have congestive heart failure; symptomatic patients should undergo corrective surgery. ECG shows right ventricular hypertrophy and chest x-ray film shows cardiomegaly and increased pulmonary blood flow.

TRUNCUS ARTERIOSlJS This abnormality occurs in less than 1 per cent of all congenital heart defects and represents a failure of septation of the primitive arterial trunk. There is only one vessel leaving the heart which gives rise to the coronary arteries, aorta, pulmonary arteries, and has only one set of semilunar valves. The common trunk overlies a ventricular septal defect which is an intergral part of this complex. The pulmonary artery may originate from this common trunk in a variety of ways. Death in the first year is the usual outcome, and survival beyond early childhood is unusual in the unoperated patient. ANATOMY AND PHYSIOLOGY. The patient with truncus arteriosus has the anatomy described above. The major significant difference among the different classifications of these patients is the size of the pulmonary arteries and the amount of flow they will accept. The patient whose pulmonary arteries arise from a common pulmonary trunk originating from the single vessel leaving the heart usually has a well developed pulmonary arterial tree and has several times more blood flowing through the lungs than is normal. Due to this magnitude of pulmonary blood flow, these patients may have a color at rest that is apparently normal or nearly normal. They tend to develop congestive heart failure due to pulmonary overcirculation. The types in which there are separate origins of the pulmonary artery from the truncus may, or may not, have large enough pulmonary arteries and sufficiently increased pulmonary blood flow to have minimal cyanosis. Where the origins of the pulmonary arteries arise from the descending aorta with bronchial collaterals interposed between the aorta and true pulmonary arteries, there is marked reduction in the pulmonary blood flow, and the child will be quite cyanotic. The patient with large pulmonary arteries and a high pressure, high flow physiologic state, will have a substantial risk of developing pulmonary vascular disease, whereas those with less flow and pressure have a lesser risk of developing this problem. PHYSICAL FINDINGS. The physical findings may be quite variable depending upon the anatomy and physiology, varying from an extreme of marked cyanosis because of markedly diminished pulmonary blood flow, with hypoxia being the primary problem, to minimal cyanosis because of a markedly increased pulmonary blood flow, with congestive heart failure being the primary problem. The patient with good coloring and large pulmonary blood flow has a murmur that may be loud and continuous like that of a patent ductus arteriosus. Variations on this murmur may be caused by the resistance to flow into the pulmonary circuit, i.e., a higher resistance shortening and softening the

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murmur. The patient with little pulmonary blood flow may have only a soft nonspecific murmur. The first heart sound in either extreme is normal, the second heart sound is usually single, and an ejection click is common. A split second heart sound does not rule out truncus arteriosus. The patients with hypoxia as their primary problem are tachypneic, limited in exercise tolerance, and grow poorly. The patients with good color tend to have congestive heart failure as their primary problem, often fail to thrive, and have increased susceptibility to pneumonia. The differential diagnoses possible could come from the group of cyanotic congenital heart defects with increased flow or decreased flow, depending upon the patient's clinical degree of cyanosis and findings on chest x-ray films. A patent ductus arteriosus with an acyanotic lesion may also have to be considered. The patient with truncus arteriosus with the pulmonary arterial supply originating from the descending aorta may be impossible to differentiate with certainty from the one with Fallot's tetrad and pulmonary atresia. Functionally, and from a management standpoint, it makes no difference. The other cyanotic defects with decreased flow are distinguishable by ECG. The patients with cyanosis and increased pulmonary blood flow may be differentiated using the clues from the x-ray films, auscultation, and ECG, but catheterization may be required. CHEST X-RAY FILMS. The chest x-ray film may vary considerably depending upon the general anatomic findings. It may vary from a picture consistent with a large left to right shunt (increased pulmonary blood flow and cardiomegaly), with a relatively normal or unremarkable appearing cardiac silhouette, clues to the diagnosis being a right aortic arch in about one-quarter of patients and "high" take-offs of the pulmonary arteries in relationship to the heart. The roentenographic appearance of the oligemic extreme cannot be differentiated from that of a severe tetrad of Fallot with marked hypoplasia of the pulmonary arteries and a small heart (because there is no volume overload) (Fig. 5). ELECTROCARDIOGRAM. Most patients show left ventricular hypertrophy or combined ventricular hypertrophy; right ventricular hypertrophy is less common. The mean QRS is usually normal (Fig. 6). ECHOCARDIOGRAM. The echo will show a single large vessel overriding the ventricular septum, but echo does not distinguish truncus from pulmonary atresia with a ventricular septal defect. Doppler echocardiography gives important clues to the relationship of the trunk and pulmonary artery, especially in the patient with a main or common pulmonary artery, by following the pulmonary blood flow between the vessels, which is different from the maneuver through a patent ductus arteriosus. CARDIAC CATHETERIZATION. Cardiac catheterization will demonstrate the anatomy and physiology. Unless an angiogram is done in the truncal vessel, left and right ventricular biplane injections may not necessarily make the diagnosis of truncus arteriosus because of the rare cases of extremely good streaming with the left ventricular

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Figure 5. A, Typical X-ray film of a patient with truncus arteriosus shows marked cardiomegaly and increased pulmonary blood flow. Note the narrow waist. B, The high take-off of the pulmonary arteries that sometimes can be seen radiologically in patients with truncus arteriosus is demonstrated nicely.

Figure 6. One possibility (combined ventricular hypertrophy) is demonstrated on this electrocardiogram from a three day old patient with truncus arteriosus .

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output directed into the aortic segment of the trunk and right ventricular output directed into the pulmonary vessel. MANAGEMENT. Management is divided into treatment of congestive heart failure with digitalis, and, if necessary, diuretics or surgical treatment for severe hypoxia. If the anatomy of the pulmonary tree is so underdeveloped as to preclude ultimate repair, palliation through shunting may only allow the infant to grow to die at an older age. The patient with a high flow pulmonary circuit is a candidate for reparative surgery. While awaiting optimal timing of surgery, the risk of developing pulmonary vascular disease from the high flow-high pressure physiology is real. In general reparative intervention (using a conduit and valve) is preferred to palliation with pulmonary artery banding, which has carried a high mortality rate even in the best of cardiac .surgical centers. With a prosthetic valve and conduit in place, precautions against subacute bacterial endocarditis must be exercised. No physical limit ations are placed on these children, but repeat surgery may be required for replacement of the conduit, for malfunction, or if the conduit becomes relatively too small. Summary The clinical course varies with the underlying structural abnormalities, particularly the size of the pulmonary arteries. Death within the first year in untreated patients is the norm. Pulmonary vascular disease is common in survivors beyond several years of life with pulmonary overcirculation without surgical intervention. Appearance on chest x-ray film may be consistent with a large left to right shunt or a tetrad, depending upon the pulmonary blood flow. The ECG usually shows left ventricular hypertrophy or combined ventricular hypertrophy, but right ventricular hypertrophy may be present. Operation should be considered in all patients with adequate sized pulmonary arteries in spite of the risks.

HYPOPLASTIC LEFT HEART SYNDROME Hypoplastic left heart syndrome represents the severe end of the spectrum of coarctation, aortic valvular stenosis, and mitral valvular stenosis. The left ventricle and ascending aorta may be hypoplastic because of mitral atresia, aortic atresia, or in some cases premature closure of the foramen ovale. Although this is usually associated with poor cardiac output (vasoconstriction and gray coloring), in order to maintain a cardiac output a portion of the right ventricular output through a patent ductus arteriosus (most often) is utilized and thus leads to cyanosis. Of the total number of congenital heart defects, the hypoplastic left heart abnormalities constitute only a very small number; however, because of the severity of the lesion, these patients present early and die within several days to several weeks of age. They constitute a high percentage of autopsy cases (25 per cent) of patients dying of a congenital heart defect in the first month of life, and 5 to 10

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per cent of the diagnoses made at catheterization performed on young infants. ANATOMY AND PHYSIOLOGY. The key to the hypoplastic left heart syndrome is the hypoplastic left ventricle associated with either aortic atresia or mitral atresia. With aortic atresia there is usually passive pulmonary vascular engorgement, and the right ventricle provides much of the cardiac output through the patent ductus arteriosus; there is pulmonary overcirculation as well. With aortic atresia retrograde flow in the ascending aorta from the patent ductus arteriosus provides coronary blood flow. The poor myocardial perfusion with aortic atresia leads to rapid decompensation. With mitral atresia other concomitant defects are usually present such as a ventricular septal defect and/or a transposed aorta which allow better hemodynamics and slightly longer longevity. CLINICAL FINDINGS. Patients appear relatively normal at birth and then rapidly develop symptoms including noticeable tachypnea and dyspnea, pallor or grayish hue to the skin (secondary to vasoconstriction), and marked congestive heart failure with hepatomegaly. Rales may be heard in the lungs. Although, most have a systolic murmur, about a third have no murmur at all. The second sound is usually prominent, and gallop sounds are present. Careful observation of coloring, generally poor pulses, and clamminess should help in differentiation from other congenital heart defects, especially TAPVR, which may have a similar appearance on chest x-ray film, and a critical aortic stenosis; both usually have entirely different ECG findings. CHEST X-RAY FILMS. The cardiac silhouette is enlarged and the pulmonary vasculature increased in the typical case of hypoplastic left ventricle. Pulmonary edema may be a striking finding. In mitral atresia and a left to right shunt at the atrial level there may be unrestricted increase in pulmonary blood flow with cardiomegaly. With pulmonary stenosis or atresia (assuming a concomitant ventricular septal defect, single ventricle, or transposed aorta), the heart size may not be striking and pulmonary blood flow decreased. This may resemble a tetrad of Fallot (Fig. 7). ELECTROCARDIOGRAM. The ECG usually shows right axis deviation, right ventricular hypertrophy, and right atrial hypertrophy. A normal ECG is not unusual (Fig. 8). ECHOCARDIOGRAM. The echo has many suggestive features of a small left heart and is extremely helpful for this diagnosis. The Doppler evaluation will assist in defining the direction of blood flow and in identifying the small aortic root. MANAGEMENT. Management is symptomatic and supportive. This condition is not correctable; if palliative procedures are done, all involved should be well awaret1iat following a palliative procedure there is no definite surgical repair possible, and if the child survives the initial procedure, death may occur at a few years of age rather than a few days or weeks. An occasional patient, because of the balance from a combination of defects, will survive to late childhood or adolescence, but this is extremely rare.

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Fig. 7

Fig. 8 Figure 7. Marked cardiomegaly and increased pulmonary blood flow are seen in this x-ray film of a newborn infant with hypoplastic left heart syndrome. Figure 8. This electrocardiogram from a patient with hypoplastic left heart syndrome shows clearly that the electrocardiogram may not always be typical (i.e., right ventricular hypertrophy and right atrial hypertrophy) in a given patient. There is right ventricular hypertrophy, however.

Summary

Patients may briefly appear to be normal after birth. Clinical findings are those of poor pulses, poor perfusion of tissues (gray coloring), and early death. The ECG lacks the normal left ventricular forces, and shows right axis deviation and right atrial and ventricular hypertrophy, but shortly after birth a normal ECG would not be unusual. There is a need to rule out treatable congenital heart defects such as critical aortic stenosis and TAPVR with obstruction.

EISENMENGER'S SYNDROME Eisenmenger's syndrome is any usually large defect that allows mixing of the left heart output (systemic circuit) and right heart out-

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put (pulmonary circuit), an acquired irreversible increase in pulmonary vascular resistance to the level of the systemic vascular resistance, and a reversal of the flow of blood so that unoxygenated blood is passed into the systemic circulation. Hypoxemia is noted, and cyanosis and clubbing of the extremities follow. In patients with Eisenmenger's syndrome, it is too late to consider surgical correction of the underlying defect. This occurs in any cardiac abnormality that causes increased pulmonary blood flow; the process is accelerated if higher than normal pulmonary artery pressures and/or hypoxemia is present. CLINICAL FINDINGS. Patients are limited in exercise tolerance, become dyspneic early, have congestive heart failure secondary to hypoxemia, angina (in some younger children expressed as epigastric rather than precordial pain), hemoptysis, syncope, and arrhythmias. "Paradoxical" embolization is a potential hazard, and the risks of polycythemia are also present. There may be little in the way of a systolic murmur because of the balanced pressures. However, the second heart sound is "banging" or "tambourine" in quality. With markedly elevated pulmonary artery pressures, there may be a murmur of pulmonic insufficiency ("Graham Steell") murmur. This murmur sounds very similar to aortic insufficiency because of the elevated pulmonary artery pressure to systemic levels. There will be no gallop rhythm or hepatomegaly unless congestive heart failure is present. Pulmonary hypertension secondary to pulmonary venous elevation from various causes is believed to be reversible. These patients do not fall into the category of Eisenmenger's syndrome. Potentially reversible causes of pulmonary hypertension such as mitral stenosis or cor triatriatum need to be considered. The combination of the clinical findings, and findings on chest x-ray films and ECG should differentiate this from other congenital heart defects. The underlying congenital heart defect leading to Eisenmenger's may not be delineated by auscultation alone. CHEST X-RAY FILMS. Classically, in the patient without congestive heart failure chest x-ray films show a normal or nearly normal sized heart with prominent central pulmonary vessels and ischemicappearing peripheral lung areas (the "pruned" appearance of the pulmonary vasculature) (Fig. 9). ELECTROCARDIOGRAM. With long-standing elevated pulmonary vascular resistance and pulmonary hypertension, there is right axis deviation, right ventricular hypertrophy, and right atrial hypertrophy. Prior to this stage combined ventricular hypertrophy may be present (Fig. 10). ECHOCARDIOGRAM. The pulmonary valve motion may be abnormal and the ratio of the right ventricular pre-ejection period to ejection time is increased. Doppler echocardiography may be able to delineate the underlying cardiac defect by the flow patterns; however, this is more difficult in patients with pulmonary hypertension because of the minimal turbulence across the defects. CARDIAC CATHETERIZATION. In view of the severe pulmonary hypertension this procedure carries significant risks. This may be the only way to delineate the etiology; the reasons for catheterization are

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ISAMU KAWABORI

Fig. 9

Fig. 10 Figure 9. Note the huge central pulmonary arteries and the marked paucity of vessels in an eight year old patient with Eisenmenger's syndrome; the "pruning" appearance is typical in the right lung. Figure 10. An electrocardiogram from a 23 year old patient with Eisenmenger's syndrom shows right ventricular hypertrophy.

to rule out a treatable cause and to be certain that irreversible pulmonary vascular disease is present. MANAGEMENT. Patients can have a variable course with periods of stabilization and deterioration. Heart failure may require digitalis, and rarely phlebotomy, which can be a life-threatening procedure. In cases of primary or acquired pulmonary hypertension with normal cardiac anatomy, poor cardiac output in addition to hypoxia may be a significant problem. Angina, hemoptysis, and syncope are poor prognostic signs.

CONGENITAL HEART DEFECTS WITH INCREASED PULMONARY BLOOD FLOW

795

Summary

Primary and secondary forms of irreversible pulmonary vascular disease exist. The second heart sound is accentuated. Congestive heart failure in advanced cases is common. Phlebotomy is dangerous, slightly less so with volume replacement. Hemoptysis, angina, and syncope are poor prognostic signs.

REFERENCES 1. Moss, A. J., Adams, F. H., and Emmanouilides, G. C.: Heart Disease in Infants, Children and Adolescents. Edition 2. Baltimore, Williams and Wilkins Co., 1977. 2. Nadas, A. S., and Tyler, D. C.: Pediatric Cardiology. Edition 3. Philadelphia, W. B. Saunders Co., 1972. 3. Rudolph, W. M.: Congenital Diseases of the Heart. Chicago, Year Book Medical Publishers, 1974.

Department of Pediatrics University of Washington School of Medicine Seattle, Washington 98195