Aortic Atresia with Normal Left Ventricle: Diagnosis in Life

Transcription

1 Aortic Atresia with Normal Left Ventricle: Diagnosis in Life M.K. Mardini, MD*, F.J. Macartney, and M.R. Deleval * Department of Pediatrics, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia; * Present address (for correspondence): Department of Pediatrics, Georgetown University Hospital, 3800 Reservoir Road, NW, Washington, DC USA; The Hospital for Sick Children, Great Ormond Street, London WC 1N3 JH, UK; FJM is supported by the Vandervell and British Heart Foundations MK Mardini, FJ Macartney, MR Deleval, Aortic Atresia With Normal Left Ventricle: Diagnosis In Life. 1986; 6(1): KEYWORDS: Aorta; Heart Septal Defects, Ventricular Summary a case of aortic atresia with ventricular septal defect and normal left ventricle is presented. The diagnosis was established in life, but the patient died during attempted definitive repair at 14 months of age. Introduction Aortic atresia is commonly associated with hypoplasia of the ascending aorta. Other assorted lesions such as mitral stenosis, hypoplastic left ventricle and intact ventricular septum occur in the majority of cases (93 96%). 1-3 About 14 cases, (4 7%) 1-7 were reported to have an adequatesized left ventricle, ventricular septal defect and nonstenotic mitral valve. In about 75% of cases of aortic atresia, there is an associated coarctation of the aorta, 8 which is 50% of cases preductal and the other 50% juxtaductal. 9 A preductal coarctation plays a significant role in restricting the retrograde coronary blood flow, which may lead to a myocardial ischemia, metabolic acidosis, and early and intractable congestive heart failure. However, Freedom 4 reported no significant coarctation of the aortic arch or mitral valve stenosis in all of six necropsied patients who had aortic atresia, ventricular septal defect and normal left ventricle. Aortic atresia accounts for about 25% of cardiac deaths in the first week and about 15% in the first month of life. 10 Survival of the patients with this condition beyond the neonatal period is rather an exception, the mean age at death being five days. 1 Eighty percent of the patients die in the first week of life. 1,11 Nadas and Mody 12 described long survival in a 3½ month old infant with aortic atresia, intact ventricular septum and hypoplastic left ventricle. Moodie, et al, 13 presented the longest survival in a child with aortic atresia, hypoplastic left ventricle, ventricular septal defect and Fanconi s anemia. This child died from respiratory infection at 3½ years of age. One patient was reported alive 1½ years following palliative surgery. 4 The patient we are reporting died at 14 months of age during an elective surgical procedure in an attempt to functionally correct the blood circulation. Our patient represents the longest survival in patients with aortic atresia with ventricular septal defect, and the second longest survival in patients with aortic atresia complex. Findings This patient was a 14-month-old infant girl who presented at the King Faisal Specialist Hospital and Research Centre at 10 months of age with tachypnea, cyanosis and poor feeding since birth. She was first hospitalized at 8 months of age at a local hospital for pneumonia and congestive heart failure. On admission to the King Faisal Specialist Hospital and Research Centre the baby appeared in mild respiratory distress with a mild degree of cyanosis. The systolic blood pressure was 70 mmhg in the upper and lower extremities. There was an active précordium with a prominent right ventricular heave. There was a grade III/VI harsh systolic ejection murmur best heard at the mid and upper left sternal border. The second heart sound was single and loud and there was mild hepatomegaly. A chest X-ray showed a large heart with pulmonary interstitial edema and increased pulmonary arterial and venous vascularity. The pulmonary artery segment was prominent. The electrocardiogram showed right ventricular hypertrophy, combined atrial enlargement and diffuse and abnormal ST-T changes. M-mode echocardiogram (Fig. 1A & B) showed a small and hypoplastic posterior vessel, with no semilunar valve leaflets visualized, and large anterior vessel that was overriding the interventricular septal defect. The right ventricle was large and hypertrophied while the left ventricle was of normal size and function. The infant underwent percutaneous right heart catheterization using the right femoral vein. The left heart was entered via an interatrial communication. The catheter also entered the transverse aortic arch from the pulmonary artery, via the patent ductus arteriosus. The catheterization data are presented in the Table.

2 Figure 1A & B. M-mode echocardiogram demonstrating the hypoplastic aorta (AO) (posterior vessel) and the large pulmonary artery (PA) (anterior vessel) that overrode the ventricular septum. The left ventricle (LV) is shown to have normal size and function with normal motion of the mitral valve leaflets. RVW - Right ventricular Wall; MV - Mitral valve; AtAo - Artretic Aortic valve; LA - Left atrium; PV - Pulmonary valve; PW - Posterior wall. Angiocardiography revealed a left ventricle of normal size and function (Fig. 2A), a high ventricular septal defect overridden by the pulmonary trunk (Fig. 2B), a large atrial septal defect and a persistent ductus arteriosus. There was a mild pre- ductal coarctation of the aorta (Fig. 3). Aortic arch injection revealed large brachiocephalic arteries, a hypoplastic ascending aorta and right and left coronary arteries of normal size and distribution (Fig. 3). At 14 months of age the baby was transferred from the King Faisal Specialist Hospital and Research Centre to the Hospital for Sick Children, Great Ormond Street, London, for surgical treatment. Under deep hypothermia, totalcooling and cardiopulmonary bypass, the large atrial septal defect and high subpulmonary ventricular septal defect were closed. A number 14 Hancock valved conduit was anastomosed to the descending thoracic aorta and then connected to the left ventricle via an apical stent. The baby died on the operating table (Fig. 4). At autopsy the presence of atrial situs solitus with normal drainage of the great veins and coronary sinus was demonstrated. There was a probe patent foramen ovale. The mitral and tricuspid valves were normal and opened into hypertrophied and enlarged right and left ventricles. There was a large perimembranous outlet ventricular septal defect reaching up to the pulmonary valve which was dilated, as were the pulmonary trunk and pulmonary arteries. The only exit from the left ventricle was the ventricular septal defect. There was no vestige of an aortic valve; indeed on passing a probe down the hypoplastic aorta it was impossible to establish any potential communication with either ventricle. The coronary arteries were given off and the aorta tapered to a point below their orifices. There was a preductal coarctation which had been made more obstructive by ligation of the ductus arteriosus, such that the lumen was only 3 mm in diameter. Otherwise the surgical repair was intact.

3 Figure 2A & B. Left ventricular angiogram showing normal size LV, the large PA is seen overriding the infundibular ventricular septal defect. MPA - Main pulmonary artery; VSD - Ventricular septal defect; IVS - Interventricular septum; CoA Coarctation of the Aorta. Figure 3. This figure shows aortic arch angiography with the catheter passing from the main pulmonary artery to the aortic arch via the patent: ductus arteriosus, demonstrating hypoplastic ascending aorta (HYPO A Ao) with the left and right coronary arteries (LCA & RCA) filling and the coarctation of the aorta (CO Ao) being seen.

4 Figure 4. An artist s view of the surgical repair procedure in the patient. It consists of closure of artrial and ventricular septal defect (ASD & VSD), valved conduit connecting the left ventricle (LV) to the thoracic descending aorta and then ligation and diversion of patent ductus arteriosus (PDA). Lung biopsy showed quite severe obstructive disease for a child of this age with extension of muscle into the periphery and longitudinal muscle bundles in the intima of many arteries accompanying respiratory bronchioli. The changes were most severe in alveolar wall arteries many of which showed medial hypertrophy, and intimai proliferation to the extent that the lumen of several vessels was occluded. Table 1. Patient data obtained by catheterization Cardiac catheterization data Site Oxygen Sat. % Pressures (mmhg) hivc 65.8 hsvc 36.9 ra /9 m= 7 rv /-6-11 pa /25 m = 48 la /12 m = 8 lv /-7-8 ao /25 m = 48 Cardiac flows and resistances Pulmonary flow Systemic flow pvr 4.5 l/min/m l/min/m units, m 2 svr 13.8 units, m 2 pvr/svr ratio 0.5 Shunt calculations Pulmonary/systemic 1.8 flow ratio Arterial blood gases on room air ph 7.46 pco 2,37 mmhg; po 2, 46 mmhg; hco 3,26 mmol/l; be, 3 mmol/l

5 Discussion Since survival in aortic atresia is dependent on retrograde perfusion of the coronary arteries from the pulmonary arteries, there must be pulmonary hypertension, a widely patent ductus arteriosus, and no obstruction to the ascending aorta or isthmus of any severity, whether from a discrete pre- ductal coarctation or from generalized hypoplasia. The only exception to this rule would be association with an aorto-pulmonary window, 5 which would bypass most causes of obstruction of the aorta. Furthermore, other than in the exceptionally rare case where there is an anatomical or physiological switch of the circulation, such as ventriculoarterial discordance, 14 survival is also dependent on the ability of pulmonary venous return to cross to the right side of the heart at the level of the atria or ventricles before encountering any obstructive lesion such as mitral stenosis or atresia. Given the high incidence of associated coarctation and aortic hypoplasia and the low incidence of either ventricular or atrial septal defect, it is hardly surprising that most cases of aortic atresia do so poorly. We ascribe the unusually long natural survival of this patient to absence of all the above risk factors except preductal coarctation and moderate aortic hypoplasia. There is in fact only one patient without ventriculo-arterial discordance that we can find reported in the literature who survived longer, a patient with hypoplasia of the ventricle and a ventricular septal defect who died at 3½ years. 13 In Roberts1 study, of 73 infants with aortic valve atresia, 95% of the patients had diminutive left ventricles, in 64% the mitral valve was abnormal and not well developed, and 36% of them had mitral atresia. Of the 5% remainder (four patients), three had abnormal mitral valves with an adequate left ventricular size (4%) and one had an intermediate-sized left ventricle with mitral atresia (1%). Freedom 4 found that 6 out of 148 (4%) and Thiene 2 found 4 out of 58 autopsies (7%) of patients with aortic atresia had a normal-sized left ventricle with a normal mitral valve. The total number of patients described with this discrete clinical pathological entity is about In the majority of these patients the correct diagnosis was made only after death. Two cases 7,15 have been correctly diagnosed in life by angiocardiography. In our case, unlike the others, the presence of a normal-sized left ventricle was anticipated prior to cardiac catheterization because of M-mode echocardiography. Otherwise the findings were remarkably similar to those described by Freedom and colleagues 7 except that in their case, there was no coarctation of the aorta. In the majority of these cases the ventricular septal defect results from malalignment between the conoin-fundibular septum and the trabecular septomarginalis and the obstructive mechanism of the sub- aortic vestibule is the fusion between the leftward and caudally deviated infundibular septum and the ventriculo infundibular fold. 4 However, in our case there was no evidence of malalignment of the ventricular septal defect involved in the infundibular septum. The mechanism of the subaortic obstruction appears to be secondary to the persistence of the ventriculo-infundibular fold. Aortic angiography was done using the transductal technique 18 which provided us with excellent delineation of the hypoplastic ascending aorta, coronary arteries, aortic arch and the location of the patent ductus arteriosus in relation to the mild coarctation in our patient. Since aortic atresia is usually a fatal condition in the first week of life, several surgical procedures have been attempted for palliation and functional correction of the blood circulation. 2,4,8,20,14-17 Since our patient had a normal mitral valve and left ventricular size and function, we attempted to perform a surgical procedure that ensures functional correction of the blood circulation by closing the patent ductus arteriosus, ventricular septal defect and atrial septal defect, and using a Hancock valve conduit to connect the left ventricle to the descending thoracic aorta. The failure of the operation can be ascribed both to the elevated pulmonary vascular resistance and to underestimation of the severity of the coarctation which blocked the free passage of blood to the brachiocephalic and coronary arteries. Had the operation been carried out earlier in life and the coarctation been adequately relieved, it might have been successful. REFERENCES 1. 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