Echocardiographic sepctrum of the hypoplastic left heart syndrome: a clinicopathologic correlation in 19 newborns

Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.

Hypoplastic left heart syndrome: is echocardiography accurate enough to guide surgical palliation?

Two-dimensional echocardiography can diagnose hypoplastic left heart syndrome. However, with the advent of the possibility of palliative open heart surgery, complete anatomic diagnosis is necessary. The anatomic findings of 15 neonates with hypoplastic left heart syndrome (age 1 to 10 days, mean 4.1) who had two-dimensional Doppler echocardiographic studies were compared with the results obtained by angiography (6 cases), surgery (11 cases) and autopsy (8 cases). Complete two-dimensional echocardiographic examination of the aortic arch, pulmonary and systemic venous return, atrial septum, ductus arteriosus and proximal coronary arteries was possible in all 15 neonates and correctly diagnosed hypoplastic left heart syndrome in each. Anatomic two-dimensional echocardiographic assessment was accurate in 13 (86%) of the 15 neonates and there were no false positive results. Undiagnosed associated abnormalities were hypoplasia of a left pulmonary artery in one patient and left superior vena cava in another. Accurate quantitation of the size of the tricuspid valve anulus, ascending aorta, pulmonary anulus and right and left pulmonary arteries was possible. Doppler examination was performed in seven patients and confirmed retrograde aortic arch flow and right to left systolic shunting in the patent ductus arteriosus. In selected neonates, surgical palliation can be attempted without angiography.

Pathologic measurements in aortic atresia

Detailed autopsy measurements were performed in 13 infants with hypoplastic left ventricle and aortic atresia. Emphasis was placed on the evaluation of changes in the right ventricle, since its function may be important in determining surgical survival. Other important aspects were the ascending aortic and transverse aortic arch diameter, the presence of left atrial obstruction, and the size of the left atrium. The development of improved 2DE and Doppler imaging will permit preoperative and sequential evaluation of these parameters. Measurements performed in this study may serve as a basis for selection of infants for palliative surgery; these procedures are being undertaken more frequently in this hitherto fatal lesion. The measurements may also serve as a basis for noninvasive serial studies of these infants postoperatively.

Quantitative angiographic and morphologic aspects of aortic valve atresia

Quantitative angiographic measurements were performed in 15 infants aged 1 to 35 days who had aortic valve atresia with intact ventricular septum and hypoplastic left ventricle. Thirteen infants had similar measurements performed at autopsy. The latter measurements were smaller than those found at angiography (because of shrinkage), but their relationship was predictable. Angiographic right ventricular (RV) volumes were 2 and 4 times normal in diastole and systole, respectively. The RV volume measured at autopsy was greater than 3 times normal. Mean RV ejection fraction was 0.40; it was below normal in 10 infants. Maximal right atrial volume was greater than 2 times normal, and mean left atrial maximal volume was two-thirds normal. The relation between circumferences of the aortic arch and ascending and descending aorta was similar at angiography and autopsy.

Echocardiographic assessment of the aortic root in syndromes with left ventricular hypoplasia

Echocardiograms and angiograms of six infants with left ventricular hypoplasia were examined. Three observations were made: (1) A normal-sized aortic root echogram may be seen in infants with mitral atresia, intact ventricular septum and normally related great arteries. (2) A recognizable mitral valve echogram may be seen in mitral atresia. (3) The true echocardiographic left ventricular dimension may be exceedingly difficult to measure, the tendency being to overestimate it. Awareness of these pitfalls with aid in the echocardiographic diagnosis of left ventricular hypoplasia in infants.

Detection of persistent ductus in hypoplastic left heart syndrome by contrast echocardiography

A patient with hypoplastic left heart syndrome was studied using contrast echocardiography after peripheral venous injection of dextrose. The combination of the parasternal and suprasternal approach allowed for identification of the right ventricular cavity, excluded the presence of right-to-left intracardiac shunts, and established normal ventriculoarterial connections. From the abdominal approach, the abdominal aorta was identified as an echo-free space corresponding to this structure in position, which became opacified after peripheral injections of dextrose into the left-hand vein. In view of the suprasternal and parasternal findings opacification of the abdominal aorta could only have occurred in the presence of a pulmonary artery to descending aorta shunt through a persistent ductus arteriosus.