Arentje Oppenheimer-Dekker

Anterolateral Muscle Bundle of the Left Ventricle, Bulboventricular Flange and Subaortic Stenosis

A hitherto unrecognized muscle bundle in the left ventricular outflow tract is described. Found between the left coronary aortic semilunar cusp and the anterior leaflet of the mitral valve, this anterolateral muscle bundle of the left ventricle is present in approximately 40 percent of normal hearts. On embryologic grounds it is suggested that this bundle is a muscular remnant of the left extremity of the bulboatrioventircular flange. It can be very prominent, causing obstruction of both the left ventricular inflow and outflow tracts.

The abnormal pulmonary venous connexion: a developmental approach

If embryonic communications exist between the splanchnic and cardinal venous systems, then they can explain variations in partially or completely abnormal pulmonary venous return as seen in congenitally malformed hearts. With this in mind, we investigated complete serial sections of 52 human embryos, ranging from 4.4 to 25 mm crown-rump length (Streeters horizons XIII-XXII) and 57 mouse embryos (Mus musculus albus CPB-S) from 7.8 to 19.7 days of gestation. Specifically, we investigated whether communications persisted between the splanchnic, the pulmonary and the cardinal venous systems. In the early stages of development, the pulmonary vascular bed shared the route of drainage of the peripheral splanchnic plexus into the umbilical-vitelline and cardinal venous systems. As the pulmonary plexus developed, it obtained a new direct route of drainage into the left atrium via the pulmonary veins. A persistence of embryonic connexions was encountered in one human and 14 mouse embryos. In all these cases, the stage of development was such that the connexions between the splanchnic and pulmonary plexuses should have disappeared. An abnormality in the development of the central pulmonary venous system was also found in the human embryo. Whether this was primary or secondary to the persistence of the embryonic connexions remained unresolved.

Muscular ventricular septal defects: A reappraisal of the anatomy

Among 79 autopsy specimens of heart 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.

Congenital mitral valve anomalies in transposition of the great arteries

In 165 hearts in transposition of the great arteries, including 16 with a ventricular septal defect and overriding pulmonary trunk and 5 with a so-called posterior transposition, the left ventricle was studied with emphasis on the morphology of the mitral valve. Distinct mitral valve anomalies were found in 36 cases (22 percent), and four categories of anomalies could be identified. Group A included 16 specimens with a cleft anterior mitral valve leaflet. The cleft was complete or partial. Partial clefts continued as a fibrous cord within the leaflet. In eight cases the cleft was situated posterior or lateral to the pulmonary ostium; in these cases the left ventricular outflow tract was not narrowed. Severe outflow tract stenosis was present in another eight cases in which the cleft was located anterior to the pulmonary ostium, usually in combination with a ventricular septal defect, and in four of these specimens there was straddling of the mitral valve. Group B included eight hearts with an abnormal size or position of the mitral valve, or both, the valve being hypoplastic or rotated clockwise, or both. Group C comprised seven hearts showing redundant left ventricular structures involving the mitral valve, among which were anomalous tissue strands, subpulmonary rings and redundant valve tissue. Group D included five specimens with deficient papillary muscles. It is concluded that an abnormal mitral valve is not unusual in hearts with transposition of the great arteries. The findings are notably important for those patients for whom anatomic surgical correction of the transposition is considered. In comparison with the venous baffle procedure, this operation makes greater demands on the structure of the mitral valve because the pressure in the left ventricle remains at systemic level. Thorough investigation of mitral valve anatomy and function is necessary before anatomic correction is considered.

The ductus arteriosus and associated cardiac anomalies in interruption of the aortic arch

SummarySeventeen heart specimens with aortic arch interruption, a ductus-dependent anomaly, were investigated. In all specimens the cardiac anatomy favoured a preferential flow into the pulmonary artery (from which the blood could reach the descending aorta through the ductus). Ten specimens had the interruption proximal to the left subclavian artery (type B) and nine of these presented solely with an outflow tract septal defect. On the other hand, six of seven specimens with the interruption distal to the left subclavian artery (type A) were associated with more complex heart malformations.The ductus was studied histologically in the 12 available arches without surgical intervention. The structure of the ductal wall, the components of which could extend considerably into the descending aorta and the pulmonary artery, ranged from that seen in a normal, mature ductus with prominent intimal cushions, to a totally abnormal persistent type with no intimal cushions and with marked elastification. This variability in ductal wall structure and the distribution of ductal tissue in the descending aorta and pulmonary artery has clinical and surgical consequences.

Anatomic characteristics of ventricular septal defect associated with coarctation of the aorta

The morphologic characteristics of ventricular septal defect (VSD) and left ventricular outflow tract were studied in 45 hearts with VSD and coarctation of the aorta (C of A). Forty-one VSDs were classified into 1 of 4 categories. The first category includes 19 central muscular VSDs (43%), among which 3 hearts had the architecture of a spontaneously closed defect. The second category includes 10 perimembranous inlet defects (23%) with overlying tricuspid valve. The third category is formed by 8 perimembranous VSDs with leftward outlet septal malalignment (18%) and the fourth category includes 4 subarterial VSDs (8%) in which leftward malalignment of a deficient outlet septum results in subpulmonary localization of the defect. In addition to the main categories, 1 membranous, 1 perimembranous trabecular, 1 apical muscular and 1 doubly committed subarterial defects were identified. The left ventricular outflow tract was assessed as normal in only 2 cases. In 43 cases the left ventricular outflow tract was compromised by 1 or more of the following anomalies: anterolateral muscle bundle, anteroseptal twist, bicuspid aortic valve or a leftward malaligned outlet septum. These findings support the hypothesis of C of A being hemodynamically induced by anomalies of the left ventricular outflow tract. Previous studies have established that muscular, membranous and perimembranous inlet defects are prone to close spontaneously, in contrast to malalignment and subarterial VSDs. The present study shows that 70% of the VSDs belong to types characterized by a high incidence of spontaneous closure.

Morphology of ventricular septal defect in complete transposition of the great arteries

The morphologic characteristics of ventricular septal defect (VSD) was studied in 50 hearts with complete transposition of the great arteries. Except for 1 membranous and 1 subarterial defect, all VSDs could be classified into 1 of 4 categories. Group A included 14 specimens with a perimembranous defect extending into inlet and trabecular septum with rightward malalignment of the outlet septum; in this group aortic arch anomalies (6 hearts) and tricuspid valve abnormalities (7 hearts) were frequently present. Group B comprised 13 hearts with perimembranous defects extending into the inlet septum; 11 hearts in this group also had an anomalous mitral valve. Group C included 13 hearts with muscular inlet defects, with signs of spontaneous closure by marginal fibrosis in 10 cases. Group D included 8 hearts with muscular infundibular defects; in 6 of these hearts the outlet septum was malaligned to the left, causing different degrees of subpulmonary stenosis. A small second VSD was present in 5 hearts. Thus, the spectrum of VSD in transposition of the great arteries is different from that of isolated VSD.

Double-outlet right ventricle without ventricular septal defect. A challenge to the embryologist? microscopic investigation

SummaryA male infant died at the age of four weeks with the following clinical diagnosis: ventricular septal defect, patent ductus arteriosus, total heart block. Postmortem X-ray investigation of the heart-lung-specimen (in which the aorta and the pulmonary trunk had a normal interrelationship, with an approximately normal caliber) and succeeding dissection of the heart chambers, revealed that both great arteries took their origin from the right ventricle; there was no ventricular septal defect and consequently the non-functioning left ventricle was rudimentary; ductus arteriosus and foramen ovale were patent.The lack of a ventricular septal defect, from embryologic viewpoint an almost obligatory part of the well-known entity of double-outlet right ventricle, compelled an extensive microscopic serial investigation of the central part of the heart septum (with the adjacent parts of tricuspid and mitral valves) and the outflow tract of the right ventricle, including the arterial orifices and a paraseptal flap of the ventral right ventricular wall.In the ventricular septum, underneath the lower left aortic semilunar cusp, at the usual site of the pars membranacea, a large mass of chondroïd tissue was found, coherent with a vast area filled with inflammatory cells, calcification, necrosis and another, smaller-sized piece of chondroid tissue in the left ventricular septal wall. Furthermore, there was pronounced endocardial fibro-elastosis of the left ventricle, demarcated by a ring of numerous thick-walled arteries with narrowed or even occluded lumina, and with several conspicuous communicating channels toward the left ventricular cavity (arterio-luminal vessels).Most likely this malformation was the result of an embryonic inflammatory process, started before the 16 mm stage and involving the region of the foramen interventriculare so violently as to occlude it before the aorta had reached its left ventricle.The endocardial fibro-elastosis, the large arterio-ventricular communications and the coronary arterial lesions are attributed to the exceeding pressure in the blind left ventricular cavity and the associated ischemia in the left ventricular wall. The ischemia might also have contributed to the aberrant cartilage formation.The significance of the findings for the functional, embryological and anatomical distinction from the usual type of double-outlet ventricle is emphasized.

Pulmonary arterial development in infants with large perimembranous ventricular septal defects associated with overriding of the aortic valve.

Intracardiac anatomy and pulmonary vascular structure were studied in 13 cases having large perimembranous ventricular septal defects associated with overriding of the aortic valve, 12 of whom died aged 2 days-9 months. In all cases the ventricular septal defect and aorta were of the same size, but the diameter of the pulmonary orifice was usually greater. Quantitative morphometric techniques were used to study the lungs. Structural adaptation to extra-uterine life was shown to have occurred normally in the 4 patients who died as neonates. In the cases aged 2 months-4 years, there was an increase in arterial medial thickness and extension of muscle, while the intra-acinar arteries were larger than normal in size and normal in number. Intimal proliferation was seen in 1 case at 4.5 months, but such proliferation caused significant obstruction only in one child aged 4 years. These findings emphasize the rapidity with which structural adaptation to extra-uterine life can occur in the patient with a large unrestrictive ventricular septal defect. A rapid increase in muscularity can be seen by 2 months of age. Should banding of the pulmonary artery be required in patients with more complicated intracardiac abnormalities in whom it is desirable to achieve a normal pulmonary vascular bed, our findings encourage its early performance, particularly in those destined for a Fontan repair.

Ventricular septal defect with normally connected and with transposed great arteries

The morphologic characteristics of 50 hearts with ventricular septal defect (VSD) and ventriculoarterial (VA) discordance were compared with those of 105 hearts with VSD and VA concordance. Of the 7 VSD types in VA concordant hearts, the 3 that occur most frequently--central muscular (26%), perimembranous with leftward malalignment of the outlet septum (18%) and perimembranous with overriding posterior artery (15%)--were absent in VA discordant hearts. Of the 6 with VA discordance, 2 principal VSD types (perimembranous with rightward outlet septum malalignment [25%] and muscular infundibular with leftward outlet septum malalignment [15%]) did not occur in VA concordant specimens. Thus, 4 VSD types occurred with VA concordance as well as with VA discordance: subarterial (12% concordance, 3% discordance); perimembranous inlet (15%, 27%); muscular inlet (10%, 27%); and membranous (4%, 3%). Of these 4 common groups, perimembranous inlet VSD with VA concordance was accompanied by tricuspid valve anomalies; however, mitral valve anomalies complicated this type of VSD with VA discordance. It is concluded that in hearts with VA concordance vs hearts with VA discordance the spectrum of VSD and ventricular morphology is different.