Perimembranous Defect Research Articles

Ventricular septal defects. Two dimensional echocardiographic and morphological correlations.

To evaluate the ability of two dimensional echocardiography to identify and classify ventricular septal defects, 280 infants and children with clinically significant ventricular septal defects were studied. Multiple precordial and subcostal echocardiographic planes were scanned in each patient in an attempt to identify the defects. Defects visualised were classified on the basis of the structures which formed their margins. Subsequent correlation of this information with angiographic (280 patients), surgical (130 patients), and pathological (31 patients) data confirmed that defects in the following sites produced a specific two dimensional echocardiographic pattern. (a) Perimembranous inlet, (b) perimembranous outlet, (c) muscular inlet, (d) single trabecular, (e) muscular outlet, and (f) doubly committed subarterial. A defect was identified and correctly classified in 252 patients. Individual defects were identified with varying degrees of accuracy. All subarterial (24 patients) defects were correctly identified and classified, as were muscular defects of the inlet (18 patients) and outlet (six patients) septa. Of the 185 perimembranous defects, 182 were identified. Only 23 of the 43 single trabecular defects were identified. Small multiple ("Swiss cheese") defects (four patients) were not identified. We conclude that two dimensional echocardiography provides a reliable non-invasive method of identifying and classifying the following ventricular septal defects: (a) perimembranous defects, (b) doubly committed subarterial defects, and (c) muscular defects of the inlet and outlet septa. In our experience it fails consistently to visualise defects in the trabecular septum.

Muscular ventricular septal defects repaired with left ventriculotomy

Between 1974 and 1979 nine patients, aged 10 months to 4 years, underwent left ventriculotomy for closure of single or multiple defects in the muscular ventricular septum. The vertical incision paralleled the anterior descending branch of the left coronary artery near the apex of the left ventricle and ranged from 2.5 to 3.5 cm in length. Four patients also had a right ventriculotomy with closure of a high perimembranous ventricular defect in two. Serial electrocardiograms indicated changes of myocardial ischemia or necrosis. Left bundle branch block did not develop in any patient. Three patients died in the early postoperative period. The six surviving patients are living and well 2 to 7 years later. There is apparent complete closure of the ventricular defects, which was documented by cardiac catheterization in four cases. Two patients had cardiomegaly and left ventricular dysfunction as assessed with echocardiographic and angiographic study, whereas four displayed good cardiac function. In three of the latter patients, cardioplegia or deep hypothermia techniques were utilized intraoperatively. The observations indicate that left ventriculotomy of limited size is an acceptable approach to the difficult problem of repair of muscular ventricular defects but may involve some risk of compromise of the coronary circulation.

Classification of ventricular septal defects.

A classification with clinical significance is proposed for ventricular septal defect based on the study of 220 hearts with defects of the ventricular septum. All had atrioventricular and ventriculoarterial concordance with normal relations of cardiac structure. For the purpose of classification, the ventricular septum was considered as possessing muscular and membranous portions, the muscular septum itself being divided into inlet, trabecular, and outlet (or infundibular) components. Defects were observed in the area of the membranous septum, termed perimembranous defects; within the muscular septum, termed muscular defects; or in the area of septum subjacent to the arterial valves, termed subarterial infundibular defects. Perimembranous defects were found extending either into the inlet, trabecular, or infundibular septa. Muscular defects were found in or between the inlet septum, trabecular septum, or infundibular septum. Review of the angiograms showed that the classification was easy to use in the catheterisation laboratory, and our observations suggest that the precision thus obtained has considerable surgical significance.

Surgical anatomy and atrioventricular conduction tissues of hearts with isolated ventricular septal defects

We have investigated a series of hearts with isolated ventricular septal defects so as to determine their surgical anatomy and the precise relationship of the atrioventricular conduction tissues to their rims. In all 63 hearts were examined, 12 of these also being studied after serial sectioning of their atrioventricular conduction systems. All defects could be divided into peri membranous, muscular, and subarterial infundibular types as previously suggested by Soto, Becker, Moulaert, Lie, and Anderson. The distinguishing feature of a perimembranous defect was that the central fibrous body formed part of its rim, this fact indicating that the conduction tissues were always to the surgeon’s right hand when the defect was approached through the right atrium. The precise relationship of the ventricular conduction tissues varied depending upon whether the perimembranous defect extended into inlet, trabecular, or infundibular components of the muscular septum. The nonbranching bundle was closest to the septal rim in inlet and trabecular defects, frequently being encased in a remnant of the interventricular membranous septum, but in those defects the nonbranching and branching bundles were also found in other specimens remote from the septal crest, carried on the left ventricular aspect of the septum. In infundibular perimembranous defects the conduction tissues were found to be remote from the septal crest. In contrast to these findings, in muscular inlet defects the penetrating and nonbranching bundles were related to the left-hand rim of the defect as viewed by the surgeon via the right atrium. In trabecular and infundibular muscular defects, and in subarterial infundibular defects when the atrial rim of the defect was muscular, the conduction tissues were again found to be remote from the edges of the defects.