Pediatr Cardiol 11:195-198, 1990
Pediatric Cardiology 9 Springer-VerlagNew York Inc. 1990
Absent Aortic Valve: A Complex Anomaly Angela E. Lin and Alvin J. Chin Department of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
SUMMARY. Seven patients (four previously cited and three new cases) with absent aortic valve cusps (leaflets), a rare and underrecognized complex congenital heart defect, are discussed. All patients were male, six full-term and one premature with nonimmunologic hydrops. None underwent operation; all died within the first week of life from low cardiac output and hypoxemia. In most instances, the only remnant of the aortic valve was a nonobstructive fibrous ridge; occasionally, it was accompanied by rudimentary leaflets or sinuses of Valsalva. Absent aortic valve was associated with other significant structural malformations in all instances, including atrioventricular valve atresia, hypoplasia or dysplasia, less commonly double outlet right ventricle, abnormal pulmonary venous connection, or left ventricular endomyocardial abnormalities. Recognition of this unusual lesion is important since it is associated with other complex malformations, causes hypoxemia (for which early positive pressure ventilation is indicated), and could he possibly palliated using the right ventricle as the systemic ventricle. KEY WORDS: Aortic valve--Aortic regurgitation--Congenital heart defect
Absence of aortic valve leaflets is an exceedingly rare cardiac malformation having been reported in two patients with double outlet right ventricle [1, 10] and two patients with normally aligned great arteries [7, 9]. Herein, we describe three additional cases of absent aortic valve with normally aligned great arteries and review the clinical and pathological features of this entity. Case Reports Patient 1 This full-term white male developed cyanosis immediately after birth. The chest radiograph showed cardiomegaly, increased pulmonary vascularity, and a reticular pattern suggesting severe pulmonary venous or lymphatic obstruction. The PO2 was 18 mmHg, despite an inspired oxygen concentration of 100%. The patient deteriorated following initiation of prostaglandin infusion, and he was moribund upon arrival at the Children's Hospital of Philadelphia (CHOP) at 18 h of age.
Address offprint requests to: Dr. Angela E. Lin, Department of Medical Genetics, West Penn Hospital, Pittsburgh, PA 15224, USA.
Only a limited two-dimensional echocardiogram could be performed during the resuscitative procedures. Subxiphoid imaging revealed atrial and visceral situs solitus, d-ventricular loop, and normally aligned great arteries. The atrial septum was abnormally thick and virtually intact. A right upper pulmonary vein drained into the left atrium. The other three pulmonary veins could not be identified. The left atrium was enlarged, and the left ventricle appeared at the lower limits of the size scale for normal. Although the mitral valve annulus size appeared normal, the leaflets were thin and the papillary muscles could not be identified. There was insufficient scanning to permit examination of the left ventricular outflow tract, aortic valve, and aortic arch. Global left ventricular systolic performance was severely diminished. Doppler examination was not performed. The presumptive diagnosis based on the radiographic and the limited twodimensional echocardiographic findings was anomalous pulmonary venous return with obstruction or critical stenosis of the pulmonary veins. The patient could not be resuscitated and died at 20 h of age. Postmortem examination revealed situs solitus of the viscera and atria, d-ventricular loop, and normally aligned great arteries. The right upper pulmonary vein was mildly hypoplastic and the other three pulmonary veins were severely stenosed, barely permitting entry of a 0.021 guide wire. The mitral valve leaflets were flimsy with minimal leaflet and chordal material; it was grossly regurgitant. The left ventricle exhibited endocardial fibroelastosis. The myocardium was grossly abnormal with spongiosum architecture. The most striking feature of the cardiac anatomy was the complete absence of the aortic valve leaflets.
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The ascending aorta, coronary ostia, and arteries were normal in size. Extracardiac malformations included cortical renal cysts, hydroureter and hydronephrosis, microcephaly, widely spaced nipples, and low-set ears. A specific genetic malformation syndrome was not identified.
Patient 2 This full-term white male was delivered by cesarean section because of placenta previa. Respiratory distress, cyanosis, and a systolic murmur developed soon after birth. Chest radiograph revealed cardiomegaly with normal pulmonary vascularity. The pO2 was 19 mmHg with an inspired oxygen concentration of 100%. There was a 2/6 systolic murmur at the left lower sternal border and severely diminished pulses throughout. The clinical diagnosis was hypoplastic left heart syndrome. Cardiac catheterization at CHOP demonstrated a left ventricular pressure of 45/25 mmHg; the waveform was identical to the aortic pressure waveform. There was a hypoplastic left ventricle with markedly diminished left ventricular performance, severe aortic regurgitation, no identifiable aortic valve leaflets, severe mitral regurgitation, and a large left-to-right shunt at the atrial level (Qp/Qs > 4). The patient died at 24 h of age. Postmortem examination revealed situs solitus of the viscera and atria, d-ventricular loop, and normally aligned great arteries. The left atrium and ventricle were hypoplastic and covered with endocardial fibroelastosis. The aortic valve leaflets were absent with only a ring of fibrous tissue at the site of the normal annulus (Fig. 1). The mitral valve leaflets were present but dysplastic. A secundum atrial septal defect and large patent ductus arteriosus were present. There was marked hemosiderosis of the liver with minimal deposits in kidney and spleen.
Patient 3 This full-term hispanic male developed cyanosis and a systolic murmur shortly after birth and was intubated. His blood gas showed a pO2 of 34 mmHg (on 100% inspired oxygen), pCO_, of 38 mmHg, HCO3 of 15 mmHg, pH 7.21. Following transfer at 4 days of age to the University of California, Los Angeles Medical Center, a repeat echocardiogram showed atrial and visceral situs solitus, d-ventricular loop, mitral atresia, Ebstein's malformation, large patent ductus arteriosus, and absent aortic valve leaflets. A long thin membrane extended from the infundibular septurn to the muscular ventricular septum. This membrane excluded the aorta from the remainder of the right ventricle but allowed free communication between the left ventricle and aorta. There was total anomalous pulmonary venous return to a leftsided ascending vertical vein that drained to the innominate vein. Doppler examination was not performed. Cardiac catheterization confirmed the ecbocardiographic findings; there was severe aortic insufficiency (Fig. 2). Left ventricular pressure was 60/40 and identical to the ascending aortic pressure. The patient died at 6 days of age. At necropsy, the aortic valve leaflets were rudimentary with a nonobstructive fibrous ridge below the coronary ostia (Fig. 3). The long, thin membrane seen on the echocardiogram was in fact a huge membranous septum; it is possible that the aortic insufficiency jet was directed at the membranous septum in utero, resulting in progressive stretching of this area. An aber-
Pediatric Cardiology Vol. 11, No. 4, 1990
rant right subclavian artery was identified. The left ventricle had a smooth-walled component and a "spongiosum-like" component. Hemosiderosis of the liver was present.
Discussion C o n g e n i t a l m a l f o r m a t i o n s o f the aortic v a l v e inc l u d e a t r e s i a , s t e n o s i s , d i s r u p t i o n of a sinus c u s p [3], a b s e n c e o f a c u s p [5], a n d c o m p l e t e a b s e n c e of all leaflets [1, 7, 9, 10]. All s e v e n c a s e s of a b s e n t aortic v a l v e in this r e v i e w w e r e a s s o c i a t e d with other complex cardiac malformations and abnormalities o f o t h e r v a l v e s . O n e r e p o r t e d p a t i e n t [1] had h y d r o p s , w h i c h was not p r e s e n t in o u r three cases. All died s h o r t l y after birth from low cardiac output and hypoxemia. R e p o r t e d p a t i e n t s i n c l u d e a male with d o u b l e o u t l e t right v e n t r i c l e , d o u b l e orifice mitre/1 valve, d y s p l a s t i c t r i c u s p i d v a l v e , a b s e n t aortic v a l v e , sev e r e left v e n t r i c u l a r h y p o p l a s i a , s e c u n d u m atrial septal defect, p a t e n t d u c t u s a r t e r i o s u s , a n d accessory s p l e e n [10]. A n o t h e r m a l e p a t i e n t had visceral h e t e r o t a x y with p o l y s p l e n i a , d o u b l e outlet right v e n t r i c l e , h y p o p l a s t i c left h e a r t v a r i a n t o f c o m p l e t e a t r i o v e n t r i c u l a r c a n a l with r e g u r g i t a n t v a l v e , hypop l a s i a o f the " m i t r a l " v a l v e a n d a cleft in its anterior leaflet, c o m m o n a t r i u m , a b s e n t aortic valve, a z y g o u s c o n t i n u a t i o n o f the i n f e r i o r v e n a c a v a , double a o r t i c arch, a n d left s u p e r i o r v e n a c a v a to the right a t r i u m [l]. R o s s i d e s c r i b e d a male with norm a l l y a l i g n e d g r e a t a r t e r i e s , h y p o p l a s t i c left heart s y n d r o m e with h y p o p l a s t i c mitral v a l v e w h i c h had a n a c c e s s o r y orifice a n d a c c e s s o r y leaflets, a n d end o c a r d i a l f i b r o e l a s t o s i s o f the h y p o p l a s t i c left ventricle [9]. S i n u s e s o f V a l s a l v a w e r e p r e s e n t ; howe v e r , the a o r t i c v a l v e leaflets w e r e a b s e n t . The p a t i e n t r e p o r t e d b y N i w a et al. had n o r m a l l y a l i g n e d g r e a t a r t e r i e s , n o d u l a r d y s p l a s i a of the t r i c u s p i d a n d p u l m o n i c v a l v e s , mild right a n d left v e n t r i c u l a r dilat a t i o n , mitral a t r e s i a , a n d e n d o c a r d i a l fibroelastosis of the left v e n t r i c l e w h i c h also h a d " b i z a r r e trabec u l a t i o n " [7]. T h e aortic v a l v e w a s c o m p l e t e l y abs e n t w i h o u t a n y f i b r o u s ridge, a l t h o u g h t h e r e was mild n a r r o w i n g . T h e left l u n g was t r i l o b e d a n d there was a h o r s e s h o e k i d n e y . I n all s e v e n c a s e s , the c o r o n a r y ostia a n d arteries w e r e n o r m a l , e x c e p t for high t a k e o f f of the left c o r o n a r y a r t e r y in o n e p a t i e n t [7]. T h e left v e n t r i c l e v a r i e d in size f r o m slightly d i l a t e d to s e v e r e l y hypoplastic. T h e r e w e r e t w o c a s e s with a b n o r m a l pulm o n a r y v e n o u s r e t u r n , that is, o n e case of total a n o m a l o u s p u l m o n a r y v e n o u s r e t u r n to a left-sided a s c e n d i n g v e r t i c a l v e i n ( p a t i e n t 3) a n d o n e case with critical s t e n o s i s o f t h r e e p u l m o n a r y v e i n s (patient 1). F i v e p a t i e n t s h a d n o r m a l l y a l i g n e d great arteries a n d t w o h a d d o u b l e o u t l e t right v e n t r i c l e .
Lin and Chin: Absent Aortic Valve
Fig. 1. Patient 2. Hypoplastic left ventricle with endocardial fibrosis and absent aortic valve with fibrous rim of annulus. LV, left ventricle; MV, mitral valve, LAA, left atrial appendage. Fig. 2. Patient 3. Angiography in the posteroanterior view (A) demonstrates massive aortic regurgitation and in the lateral view (B) demonstrates "partitioning" of the left ventricle. Ao, aorta; LV, left ventricle; MS, membranous septum. Fig. 3. Patient 3. Absent aortic valve leaflets with a ridge of dysplastic leaflet tissue and abnormal left ventricular trabeculations. MS, membranous septum; Ao V, aortic valve.
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Abnormalities of the ventricular myocardium were striking. Endocardial fibroelastosis was noted in our patients 1 and 2 and the patients reported by Rossi and Niwa [7, 9]. The myocardial architecture was abnormal in patients 1 and 3 and Niwa's patient [7]. A comparison between absent aortic valve and absent pulmonary valve [4] reveals some similarities and differences. The latter is usually accompanied by a malalignment-type ventricular septal defect and some degree of pulmonary stenosis at the valvar and infundibutar level ("tetralogy of Fallot with absent pulmonary valve"). Poststenotic dilata-
198
tion of the main and proximal branch pulmonary arteries can be severe. Absent aortic valve was not associated with obstruction to aortic outflow or poststenotic dilatation. Despite the appellation "absent" pulmonary valve, some remnant of pulmonary valve leaflet tissue, albeit dysplastic, is present. In contrast, absent aortic valve is usually associated with only a faint endothelial ridge at the annulus, although rudimentary leaflets were noted in patient 3. The hemodynamic effects of severe aortic regurgitation in utero are unknown. Postnatally, severe aortic regurgitation would be worsened by the increase in systemic vascular resistance accompanying the removal of the (low-resistance) placenta from the circuit. In addition to resulting in low cardiac output, absent aortic valve causes elevated left ventricular diastolic pressure which in turn results in pulmonary venous hypertension and impaired oxygenation. Two of our patients developed this; the other was spared the effects on pulmonary venous pressure of high left ventricular end-diastolic pressure because there was total anomalous pulmonary venous connection. Prenatal echocardiography was utilized [1] to diagnose this defect and could be offered during subsequent pregnancies to mothers of affected infants. Because of the rapid hemodynamic deterioration following delivery, prenatal diagnosis would facilitate neonatal critical care. None of these seven patients underwent surgery. In the presence of a normal tricuspid valve, palliation may be achieved by the Norwood procedure [8] or, presumably, by cardiac transplantation. The pathogenesis of this disorder is unknown. The aortic and pulmonary valves are derived from three mounds of endocardial cushion tissue.Valvulogenesis is postulated to occur by cellular proliferation at the stagnant margins of the downstream end of the cardiac tube [6]. To account for the absence of the aortic valve leaflets, one could speculate that a disturbance in embryonic blood flow prevented
Pediatric Cardiology Vol. 11, No. 4, 1990
the normal hemodynamic stimulus or that a selective injury occurred after the valve formation. Disturbances in embryonic cardiac function have been postulated to be the basis of some forms of congenital heart defects [2]. That all seven patients were male suggests Xlinked recessive inheritance or other X-linked factors.
Acknowledgment: We thank Dr. Paul Weinberg for the materials
on patient 2.
References 1. Bierman FZ, Yeh M-N, Swersky S, Martin E, Wigger JH, Fox H (1984) Absence of the aortic valve: Antenatal and postnatal two-dimensional doppler echocardiographic features. J Am Coil Cardiol 3:833-837 2. Clark EB (1986) Cardiac embryology. Its relevance to congenital heart disease. A m J Dis Child 140:41-44 3. Dolora A, Manetti A, Magi-Diligenti L, Gori F (1979) Aortic regurgitation in a newborn. Br Heart J 42:606-607 4. Fischer DR, Neches WH, Beerman LB, Fricker FJ, Siewers RD, Lenox CC, Park SC (1984) Tetralogy of Fallot with absent pulmonic valve: Analysis of 17 patients. Am J Cardiol 53:1433-1437
5. Hoa T-Q, Smolinsky A, Neufeld HN, Goor DA (1986) Dysplastic aortic valve with absence of aortic valve cusp: An unreported cause of congenital aortic insufficiency. J Thorac Cardiovasc Surg 91:471-472
6. Marron BJ, Hutchins GM (1975) The development of the semi-lunar valves of the human heart. Am J Pathol 74:331340 7. Niwa K, Ikeola F, Miyamoto H, Nakajima H, Ando M (1987) Absent aortic valve with normally related great arteries. Heart Vessels 3:104-107 8. Pigott JD, Murphy JD, Barber G, Norwood WI (1988) Palliative surgery for hypoplastic left heart syndrome. Ann Thorac Surg 45:122-128
9. Rossi MB, Ho SW, Tasker RC (1986) Absent aortic valve leaflets. Int J Cardiol 11:235-237 10. Toews WH, Lortscher RH, Kelminson LL (1975) Double outlet right ventricle with absent aortic valve. Chest 68:381382
Pediatric Cardiology 9 Springer-VerlagNew York Inc. 1990
Absent Aortic Valve: A Complex Anomaly Angela E. Lin and Alvin J. Chin Department of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, and the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
SUMMARY. Seven patients (four previously cited and three new cases) with absent aortic valve cusps (leaflets), a rare and underrecognized complex congenital heart defect, are discussed. All patients were male, six full-term and one premature with nonimmunologic hydrops. None underwent operation; all died within the first week of life from low cardiac output and hypoxemia. In most instances, the only remnant of the aortic valve was a nonobstructive fibrous ridge; occasionally, it was accompanied by rudimentary leaflets or sinuses of Valsalva. Absent aortic valve was associated with other significant structural malformations in all instances, including atrioventricular valve atresia, hypoplasia or dysplasia, less commonly double outlet right ventricle, abnormal pulmonary venous connection, or left ventricular endomyocardial abnormalities. Recognition of this unusual lesion is important since it is associated with other complex malformations, causes hypoxemia (for which early positive pressure ventilation is indicated), and could he possibly palliated using the right ventricle as the systemic ventricle. KEY WORDS: Aortic valve--Aortic regurgitation--Congenital heart defect
Absence of aortic valve leaflets is an exceedingly rare cardiac malformation having been reported in two patients with double outlet right ventricle [1, 10] and two patients with normally aligned great arteries [7, 9]. Herein, we describe three additional cases of absent aortic valve with normally aligned great arteries and review the clinical and pathological features of this entity. Case Reports Patient 1 This full-term white male developed cyanosis immediately after birth. The chest radiograph showed cardiomegaly, increased pulmonary vascularity, and a reticular pattern suggesting severe pulmonary venous or lymphatic obstruction. The PO2 was 18 mmHg, despite an inspired oxygen concentration of 100%. The patient deteriorated following initiation of prostaglandin infusion, and he was moribund upon arrival at the Children's Hospital of Philadelphia (CHOP) at 18 h of age.
Address offprint requests to: Dr. Angela E. Lin, Department of Medical Genetics, West Penn Hospital, Pittsburgh, PA 15224, USA.
Only a limited two-dimensional echocardiogram could be performed during the resuscitative procedures. Subxiphoid imaging revealed atrial and visceral situs solitus, d-ventricular loop, and normally aligned great arteries. The atrial septum was abnormally thick and virtually intact. A right upper pulmonary vein drained into the left atrium. The other three pulmonary veins could not be identified. The left atrium was enlarged, and the left ventricle appeared at the lower limits of the size scale for normal. Although the mitral valve annulus size appeared normal, the leaflets were thin and the papillary muscles could not be identified. There was insufficient scanning to permit examination of the left ventricular outflow tract, aortic valve, and aortic arch. Global left ventricular systolic performance was severely diminished. Doppler examination was not performed. The presumptive diagnosis based on the radiographic and the limited twodimensional echocardiographic findings was anomalous pulmonary venous return with obstruction or critical stenosis of the pulmonary veins. The patient could not be resuscitated and died at 20 h of age. Postmortem examination revealed situs solitus of the viscera and atria, d-ventricular loop, and normally aligned great arteries. The right upper pulmonary vein was mildly hypoplastic and the other three pulmonary veins were severely stenosed, barely permitting entry of a 0.021 guide wire. The mitral valve leaflets were flimsy with minimal leaflet and chordal material; it was grossly regurgitant. The left ventricle exhibited endocardial fibroelastosis. The myocardium was grossly abnormal with spongiosum architecture. The most striking feature of the cardiac anatomy was the complete absence of the aortic valve leaflets.
196
The ascending aorta, coronary ostia, and arteries were normal in size. Extracardiac malformations included cortical renal cysts, hydroureter and hydronephrosis, microcephaly, widely spaced nipples, and low-set ears. A specific genetic malformation syndrome was not identified.
Patient 2 This full-term white male was delivered by cesarean section because of placenta previa. Respiratory distress, cyanosis, and a systolic murmur developed soon after birth. Chest radiograph revealed cardiomegaly with normal pulmonary vascularity. The pO2 was 19 mmHg with an inspired oxygen concentration of 100%. There was a 2/6 systolic murmur at the left lower sternal border and severely diminished pulses throughout. The clinical diagnosis was hypoplastic left heart syndrome. Cardiac catheterization at CHOP demonstrated a left ventricular pressure of 45/25 mmHg; the waveform was identical to the aortic pressure waveform. There was a hypoplastic left ventricle with markedly diminished left ventricular performance, severe aortic regurgitation, no identifiable aortic valve leaflets, severe mitral regurgitation, and a large left-to-right shunt at the atrial level (Qp/Qs > 4). The patient died at 24 h of age. Postmortem examination revealed situs solitus of the viscera and atria, d-ventricular loop, and normally aligned great arteries. The left atrium and ventricle were hypoplastic and covered with endocardial fibroelastosis. The aortic valve leaflets were absent with only a ring of fibrous tissue at the site of the normal annulus (Fig. 1). The mitral valve leaflets were present but dysplastic. A secundum atrial septal defect and large patent ductus arteriosus were present. There was marked hemosiderosis of the liver with minimal deposits in kidney and spleen.
Patient 3 This full-term hispanic male developed cyanosis and a systolic murmur shortly after birth and was intubated. His blood gas showed a pO2 of 34 mmHg (on 100% inspired oxygen), pCO_, of 38 mmHg, HCO3 of 15 mmHg, pH 7.21. Following transfer at 4 days of age to the University of California, Los Angeles Medical Center, a repeat echocardiogram showed atrial and visceral situs solitus, d-ventricular loop, mitral atresia, Ebstein's malformation, large patent ductus arteriosus, and absent aortic valve leaflets. A long thin membrane extended from the infundibular septurn to the muscular ventricular septum. This membrane excluded the aorta from the remainder of the right ventricle but allowed free communication between the left ventricle and aorta. There was total anomalous pulmonary venous return to a leftsided ascending vertical vein that drained to the innominate vein. Doppler examination was not performed. Cardiac catheterization confirmed the ecbocardiographic findings; there was severe aortic insufficiency (Fig. 2). Left ventricular pressure was 60/40 and identical to the ascending aortic pressure. The patient died at 6 days of age. At necropsy, the aortic valve leaflets were rudimentary with a nonobstructive fibrous ridge below the coronary ostia (Fig. 3). The long, thin membrane seen on the echocardiogram was in fact a huge membranous septum; it is possible that the aortic insufficiency jet was directed at the membranous septum in utero, resulting in progressive stretching of this area. An aber-
Pediatric Cardiology Vol. 11, No. 4, 1990
rant right subclavian artery was identified. The left ventricle had a smooth-walled component and a "spongiosum-like" component. Hemosiderosis of the liver was present.
Discussion C o n g e n i t a l m a l f o r m a t i o n s o f the aortic v a l v e inc l u d e a t r e s i a , s t e n o s i s , d i s r u p t i o n of a sinus c u s p [3], a b s e n c e o f a c u s p [5], a n d c o m p l e t e a b s e n c e of all leaflets [1, 7, 9, 10]. All s e v e n c a s e s of a b s e n t aortic v a l v e in this r e v i e w w e r e a s s o c i a t e d with other complex cardiac malformations and abnormalities o f o t h e r v a l v e s . O n e r e p o r t e d p a t i e n t [1] had h y d r o p s , w h i c h was not p r e s e n t in o u r three cases. All died s h o r t l y after birth from low cardiac output and hypoxemia. R e p o r t e d p a t i e n t s i n c l u d e a male with d o u b l e o u t l e t right v e n t r i c l e , d o u b l e orifice mitre/1 valve, d y s p l a s t i c t r i c u s p i d v a l v e , a b s e n t aortic v a l v e , sev e r e left v e n t r i c u l a r h y p o p l a s i a , s e c u n d u m atrial septal defect, p a t e n t d u c t u s a r t e r i o s u s , a n d accessory s p l e e n [10]. A n o t h e r m a l e p a t i e n t had visceral h e t e r o t a x y with p o l y s p l e n i a , d o u b l e outlet right v e n t r i c l e , h y p o p l a s t i c left h e a r t v a r i a n t o f c o m p l e t e a t r i o v e n t r i c u l a r c a n a l with r e g u r g i t a n t v a l v e , hypop l a s i a o f the " m i t r a l " v a l v e a n d a cleft in its anterior leaflet, c o m m o n a t r i u m , a b s e n t aortic valve, a z y g o u s c o n t i n u a t i o n o f the i n f e r i o r v e n a c a v a , double a o r t i c arch, a n d left s u p e r i o r v e n a c a v a to the right a t r i u m [l]. R o s s i d e s c r i b e d a male with norm a l l y a l i g n e d g r e a t a r t e r i e s , h y p o p l a s t i c left heart s y n d r o m e with h y p o p l a s t i c mitral v a l v e w h i c h had a n a c c e s s o r y orifice a n d a c c e s s o r y leaflets, a n d end o c a r d i a l f i b r o e l a s t o s i s o f the h y p o p l a s t i c left ventricle [9]. S i n u s e s o f V a l s a l v a w e r e p r e s e n t ; howe v e r , the a o r t i c v a l v e leaflets w e r e a b s e n t . The p a t i e n t r e p o r t e d b y N i w a et al. had n o r m a l l y a l i g n e d g r e a t a r t e r i e s , n o d u l a r d y s p l a s i a of the t r i c u s p i d a n d p u l m o n i c v a l v e s , mild right a n d left v e n t r i c u l a r dilat a t i o n , mitral a t r e s i a , a n d e n d o c a r d i a l fibroelastosis of the left v e n t r i c l e w h i c h also h a d " b i z a r r e trabec u l a t i o n " [7]. T h e aortic v a l v e w a s c o m p l e t e l y abs e n t w i h o u t a n y f i b r o u s ridge, a l t h o u g h t h e r e was mild n a r r o w i n g . T h e left l u n g was t r i l o b e d a n d there was a h o r s e s h o e k i d n e y . I n all s e v e n c a s e s , the c o r o n a r y ostia a n d arteries w e r e n o r m a l , e x c e p t for high t a k e o f f of the left c o r o n a r y a r t e r y in o n e p a t i e n t [7]. T h e left v e n t r i c l e v a r i e d in size f r o m slightly d i l a t e d to s e v e r e l y hypoplastic. T h e r e w e r e t w o c a s e s with a b n o r m a l pulm o n a r y v e n o u s r e t u r n , that is, o n e case of total a n o m a l o u s p u l m o n a r y v e n o u s r e t u r n to a left-sided a s c e n d i n g v e r t i c a l v e i n ( p a t i e n t 3) a n d o n e case with critical s t e n o s i s o f t h r e e p u l m o n a r y v e i n s (patient 1). F i v e p a t i e n t s h a d n o r m a l l y a l i g n e d great arteries a n d t w o h a d d o u b l e o u t l e t right v e n t r i c l e .
Lin and Chin: Absent Aortic Valve
Fig. 1. Patient 2. Hypoplastic left ventricle with endocardial fibrosis and absent aortic valve with fibrous rim of annulus. LV, left ventricle; MV, mitral valve, LAA, left atrial appendage. Fig. 2. Patient 3. Angiography in the posteroanterior view (A) demonstrates massive aortic regurgitation and in the lateral view (B) demonstrates "partitioning" of the left ventricle. Ao, aorta; LV, left ventricle; MS, membranous septum. Fig. 3. Patient 3. Absent aortic valve leaflets with a ridge of dysplastic leaflet tissue and abnormal left ventricular trabeculations. MS, membranous septum; Ao V, aortic valve.
197
Abnormalities of the ventricular myocardium were striking. Endocardial fibroelastosis was noted in our patients 1 and 2 and the patients reported by Rossi and Niwa [7, 9]. The myocardial architecture was abnormal in patients 1 and 3 and Niwa's patient [7]. A comparison between absent aortic valve and absent pulmonary valve [4] reveals some similarities and differences. The latter is usually accompanied by a malalignment-type ventricular septal defect and some degree of pulmonary stenosis at the valvar and infundibutar level ("tetralogy of Fallot with absent pulmonary valve"). Poststenotic dilata-
198
tion of the main and proximal branch pulmonary arteries can be severe. Absent aortic valve was not associated with obstruction to aortic outflow or poststenotic dilatation. Despite the appellation "absent" pulmonary valve, some remnant of pulmonary valve leaflet tissue, albeit dysplastic, is present. In contrast, absent aortic valve is usually associated with only a faint endothelial ridge at the annulus, although rudimentary leaflets were noted in patient 3. The hemodynamic effects of severe aortic regurgitation in utero are unknown. Postnatally, severe aortic regurgitation would be worsened by the increase in systemic vascular resistance accompanying the removal of the (low-resistance) placenta from the circuit. In addition to resulting in low cardiac output, absent aortic valve causes elevated left ventricular diastolic pressure which in turn results in pulmonary venous hypertension and impaired oxygenation. Two of our patients developed this; the other was spared the effects on pulmonary venous pressure of high left ventricular end-diastolic pressure because there was total anomalous pulmonary venous connection. Prenatal echocardiography was utilized [1] to diagnose this defect and could be offered during subsequent pregnancies to mothers of affected infants. Because of the rapid hemodynamic deterioration following delivery, prenatal diagnosis would facilitate neonatal critical care. None of these seven patients underwent surgery. In the presence of a normal tricuspid valve, palliation may be achieved by the Norwood procedure [8] or, presumably, by cardiac transplantation. The pathogenesis of this disorder is unknown. The aortic and pulmonary valves are derived from three mounds of endocardial cushion tissue.Valvulogenesis is postulated to occur by cellular proliferation at the stagnant margins of the downstream end of the cardiac tube [6]. To account for the absence of the aortic valve leaflets, one could speculate that a disturbance in embryonic blood flow prevented
Pediatric Cardiology Vol. 11, No. 4, 1990
the normal hemodynamic stimulus or that a selective injury occurred after the valve formation. Disturbances in embryonic cardiac function have been postulated to be the basis of some forms of congenital heart defects [2]. That all seven patients were male suggests Xlinked recessive inheritance or other X-linked factors.
Acknowledgment: We thank Dr. Paul Weinberg for the materials
on patient 2.
References 1. Bierman FZ, Yeh M-N, Swersky S, Martin E, Wigger JH, Fox H (1984) Absence of the aortic valve: Antenatal and postnatal two-dimensional doppler echocardiographic features. J Am Coil Cardiol 3:833-837 2. Clark EB (1986) Cardiac embryology. Its relevance to congenital heart disease. A m J Dis Child 140:41-44 3. Dolora A, Manetti A, Magi-Diligenti L, Gori F (1979) Aortic regurgitation in a newborn. Br Heart J 42:606-607 4. Fischer DR, Neches WH, Beerman LB, Fricker FJ, Siewers RD, Lenox CC, Park SC (1984) Tetralogy of Fallot with absent pulmonic valve: Analysis of 17 patients. Am J Cardiol 53:1433-1437
5. Hoa T-Q, Smolinsky A, Neufeld HN, Goor DA (1986) Dysplastic aortic valve with absence of aortic valve cusp: An unreported cause of congenital aortic insufficiency. J Thorac Cardiovasc Surg 91:471-472
6. Marron BJ, Hutchins GM (1975) The development of the semi-lunar valves of the human heart. Am J Pathol 74:331340 7. Niwa K, Ikeola F, Miyamoto H, Nakajima H, Ando M (1987) Absent aortic valve with normally related great arteries. Heart Vessels 3:104-107 8. Pigott JD, Murphy JD, Barber G, Norwood WI (1988) Palliative surgery for hypoplastic left heart syndrome. Ann Thorac Surg 45:122-128
9. Rossi MB, Ho SW, Tasker RC (1986) Absent aortic valve leaflets. Int J Cardiol 11:235-237 10. Toews WH, Lortscher RH, Kelminson LL (1975) Double outlet right ventricle with absent aortic valve. Chest 68:381382
