Editorial note New light on the morphogenesis of atrioventricular septal defects

Atypical form of atrioventricular septal defect without left axis deviation: relation between morphology and unusual QRS axis

OBJECTIVE

To clarify the morphological features relating to an intermediate axis or a right axis deviation in atrioventricular septal defect (AVSD).

SUBJECTS

135 patients with typical AVSD and with nine patients with atypical AVSD, characterised by a well formed atrial septum, a milder downward displacement of the atrioventricular valves, and a shorter length of the ostium primum defect.

MAIN OUTCOME MEASURES

Relation between morphology and electrocardiographic and vectorcardiographic findings; prevalence of Down's syndrome and of other cardiac anomalies.

RESULTS

All nine patients with atypical AVSD had an unusual mean frontal QRS axis compared with six of the 135 patients (4%) with typical AVSD (p < 0.01). All eight patients who underwent the vector analyses showed atypical movement of the QRS loop--that is, an initial left inferior movement in the frontal loop (eight patients) and counter-clockwise rotation in the sagittal loop (seven). The corresponding values for 119 patients with typical AVSD were 20 and 22 patients (p < 0.01). Seven patients with atypical AVSD (78%) and 55 (41%) with typical AVSD had Down's syndrome (p < 0.05). None of the twenty one patients with additional cardiac anomalies had atypical AVSD, an unusual QRS axis, or unusual movement in the QRS loop.

CONCLUSIONS

The atypical morphology, supposedly related to the degree of posteroinferior displacement of the conduction system, was one of the causes of unusual movement of the QRS loop in AVSD.

Echocardiographic evaluation of atrioventricular orifice anatomy in children with atrioventricular septal defect

In atrioventricular (AV) septal defect, the common AV valve can have a common orifice or can be divided by bridging leaflet tissue into two separate orifices. To determine the accuracy of a two-dimensional echocardiographic technique devised specifically for evaluation of the number of AV valve orifices, all 69 children undergoing surgical repair of AV septal defect from April 1987 to August 1990 were examined prospectively. The presence of bridging leaflet tissue and the number of AV valve orifices were determined with use of a subcostal imaging plane. From a standard subcostal four-chamber view, the plane of sound was rotated 30 degrees to 45 degrees clockwise until the AV valve was seen en face. The plane of sound was then tilted from a superior to an inferior direction so that cross-sectional views of the AV valve were examined from the inferior margin of the atrial septum to the superior margin of the ventricular septum. Of the 69 patients, 6 (9%) were excluded because the appropriate subcostal images were not obtained (in 3 because of obesity and in 3 as a result of operator failure). The remaining 63 children, ranging in age from 1 day to 13.5 years and in weight from 1 to 55 kg, constituted the study group. Echocardiographic results were compared with surgical observations in 62 patients and with autopsy findings in 1 patient. With the two-dimensional echocardiographic technique, 32 of 33 patients with a common orifice and 28 of 30 patients with two separate AV valve orifices were correctly identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative transesophageal echocardiography of atrioventricular septal defect

To determine the accuracy and utility of single-plane transesophageal echocardiography in analyzing atrioventricular (AV) septal defect, intraoperative transesophageal echocardiography was performed before and after institution of cardiopulmonary bypass in 16 patients (age 24 days to 14 years, weight 3 to 47 kg). Prebypass transesophageal echocardiography (including two-dimensional echocardiography, Doppler color flow mapping and pulsed wave Doppler ultrasound) correctly diagnosed divided AV valve, common AV valve and unbalanced AV valve, as well as atrial or ventricular septal defect, or both, in all cases. It correctly analyzed AV valve regurgitation in all 10 patients with right and all 14 with left AV valve regurgitation and correctly analyzed 30 of 33 additional cardiac anomalies. Transesophageal echocardiography was able to detect the absence of normal pulmonary venous connections but failed to demonstrate all of the complex anomalous pulmonary venous connections in three patients with atrial isomerism. Postbypass transesophageal echocardiography documented the absence of a significant residual shunt in 11 of 11 patients undergoing corrective surgery and verified residual AV valve regurgitation in 7 of 9 patients with tricuspid regurgitation and 11 of 13 with mitral regurgitation. Transesophageal echocardiographic information that altered or refined the surgical treatment was obtained in 5 (31%) of 16 patients. Epicardial and transesophageal echocardiography results were concordant in all 13 patients in whom both were performed. Transesophageal echocardiography provides useful and accurate imaging of the important two-dimensional, pulsed wave Doppler ultrasound and Doppler color flow mapping features in AV septal defect.