London, UK summARY 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 itselfbeing 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.In this report, we present a simplified concept for the classification of ventricular septal defects based on the study of over 200 pathological specimens with atrioventricular concordance, ventriculoarterial concordance, and usual relations of intracardiac structures. We have shown it to be useful for angiographic diagnosis and we believe it to have considerable surgical relevance. Subjects and methodsThe hearts studied were taken from the cardiopathological collections of the Cardiothoracic Institute, Brompton Hospital, London; the Royal

In order to elucidate some of the unexplained phenomena in prolonged patency of the ductus arteriosus in preterm infants, the histology of the ductus was studied in 27 eases. Some PROLONGED PATENCY of the ductus arteriosus in preterm infants with a large left-to-right shunt often leads to cardiopulmonary distress. Its increased incidence over the last few years ~ is probably due to improved neonatal intensive care. A satisfactory explanation of the cause of delayed ductal closure in preterm infants has not been found. Sooner or later spontaneous closure is seen in most infants. Immediate closure of the ductus after birth in very immature infants may also occur. 1-~ In recent years pharmacologic closure with indomethacin has been attempted, >" and closure may be obtained in this way. However, both lack of response and reopening after initial contraction with indomethacin have been observed. ~-~ To contribute to a better understanding of the above mentioned problems, we did a histologic study of the ductus tissue of preterm human infants. SUBJECTS AND METHODStThe ducts of 27 preterm infants, with gestational ages ranging from 24 to 37 weeks and varying in age from 10 tTabulated clinical data available on special request. hours to 5F2 months, were studied. The ducts, with the adjacent parts of the aorta and pulmonary artery, were removed at autopsy. The material was fixed in alcohol/ glycerine and prepared routinely for histologic examination. All specimens were completely serially sectioned and the sections stained alternately with hematoxylin-eosin, azan, resorcin fuchsin, and van Gieson elastic tissue stain. See related article, p. 94.For comparison, we also studied 15 ducts from fetuses with a gestational age of 16 to 23 weeks, who either were born dead or did not live longer than one hour. Furthermore, 40 ducts from term infants ranging in age from 0 hours to several years, were investigated. Some of the results of this last group have been described previouslyY lo These latter studies indicated that in case of permanent patency of the ductus, also referred to as persistent patency, there is a primary anatomic defect of the ductus.The bistologic findings in the preterm infants were related to clinical data, birth weight, asphyxia at birth, incidence of respiratory distress, use of assisted ventilation, prolonged patency of the ductus, and cause of death. All infants had been admitted to a neonataI intensive care unit. The clinical recognition of patency of the ductus arteriosus during the first week of life was sometimes very difficult. It was often impossible to separate those infants

This investigation presents additional evidence for the hemodynamic influence of intracardiac anomalies on the development of the aortic arch, based on measurements of different parts of the great vessels. Criteria are given to define the normal aortic arch and the different anomalies of the aortic arch, such as interruption, atresia, tubular hypoplasia, hypoplasia, abnormal long segment and juxtaductal coarctation. Two types of of malignment venentricular septal defects are described to illustrate how prenatal intracardiac flow disturbances can account for various aortic arch patterns. An explanation is proposed as to how reduced blood flow through the embryonic preductal aorta may contribute to the pathogenesis of all dimensional anomalies of the aortic arch.

Histologic study of the persistent ductus arteriosus in case of a congenital rubella syndrome revealed that this persistency is probably due to an arrest in the development of the ductus. Histologically, it resembles a very immature ductus and not the most common type of persistent ductus arteriosus. The earlier finding, that in the human ductus arteriosus, the presence of an extensive subendothelial elastic lamina is incompatible with anatomic sealing, still holds.

SUMMARY The histology ofthe ductus arteriosus was studied after prostaglandin E1 (PGE1) administration in 4 infants with ductus dependent cardiac malformations. Pronounced pathological changes were found in each instance. The changes consisted of oedema of the media with separation of medial components by clear spaces, pathological interruptions of the internal elastic lamina, and intimal lacerations, some of which extended into the media.The findings suggest that PGE1 administration has a profound weakening effect on the structure of the wall of the ductus arteriosus, rendering the vessel prone to laceration.

Among 79 autopsy specimens of heads with an isolated ventricular septal defect, there were 29 cases of muscular defect. Among 60 hearts with complete transposition Of the great arteries and a ventricular septal defect, there were 13 cases with a muscular defect. All muscular defects could be classified in three different types, based on the specific Pathologic anatomy of the ventricular septum. The central and posterior defects were usually large and single, the marginal defects were frequently small and multiple. In hearts with transposition, central muscular defects were extremely rare, whereas these defects were by far the most frequent muscular defects in isolated ventricular septal defect. Alternatively, the posterior type was more common in cases of transposition. Marginal muscular defects were rare in both groups of malformations.

Two-dimensional echocardiography was performed on a patient with criss-cross atrioventricular (AV) relationship and ventriculo-arterial discordance. A systematic approach from the subcostal area revealed the complex cardiac pathology including the criss-cross AV relationship of right and left heart, indicating that this very abnormal relationship can be identified echocardiographically. The echocardiographic findings were confirmed by angiocardiography. Post-mortem investigation showed that much of the complexity, including the criss-cross AV relationship, had been caused by a secondary leftward torsion of the entire ventricular part of the heart.

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