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Longitudinal dissociation of the aggregated specialized cardiomyocytes within the non-branching portion of atrioventricular conduction axis has proved a controversial topic for both morphologists and electrophysiologists. We have now used morphological methods, including three-dimensional assessment, to revisit, in human, canine, and bovine hearts, the presence or absence of interconnections between the aggregated cardiomyocytes making up the non-branching bundle. We analyzed three datasets from human and canine hearts, and two from bovine hearts, using longitudinal and orthogonal serial histological sections. In addition, we assessed three hearts using translucent India ink injected specimens, permitting assessment of the three-dimensional arrangement of the cardiomyocytes. Using the longitudinal sections, we found numerous oblique interconnections between the groups of specialized cardiomyocytes. When assessing orthogonal sections, we noted marked variation in the grouping of the cardiomyocytes. We interpreted this finding as evidence of bifurcation and convergence of the groups seen in the longitudinal sections. The three-dimensional assessment of the bovine material confirmed the presence of the numerous interconnections. The presence of multiple connections between the cardiomyocytes in the non-branching bundle rules out the potential for longitudinal dissociation.

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OBJECTIVE: To study patients with atrioventricular septal defect to determine the pathognomonic morphological features of the lesion and the relation between the septal structures and the atrioventricular junction. Setting : Tertiary level paediatric cardiology centre. METHODS: Cross sectional echocardiograms from 60 patients were reviewed using qualitative and quantitative analysis. The unifying feature was the presence of a common atrioventricular junction. The overall dimensions of the septal defect were determined and related to the plane of the common junction; the extent of both the atrial and the ventricular septal components was then measured according to the site of closure of the bridging leaflets. RESULTS: In 48 cases, the common junction was guarded by a common valvar orifice, but in 12 cases there were separate right and left valvar orifices. Irrespective of the valvar morphology, no significant difference was found between the groups in terms of the dimensions of the atrial and ventricular septal components. In all patients, the hole permitting shunting at atrial level extended below the plane of the atrioventricular junction, with a variable position of the leading edge of the atrial septum itself. CONCLUSIONS: The atrioventricular junction is a common structure irrespective of valvar morphology. In spite of the presence of unequivocal shunting at atrial level, the atrial septum is usually a well formed structure, even extending in some below the level of the common atrioventricular junction.

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Postmortem examination of 62 hearts with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections) and an accompanying ventricular septal defect was performed to determine the morphologic variability of ventricular septal defects and to explore the surgical implications of these defects. Particular attention was directed toward assessing alignment of the outlet septum relative to the muscular septum. Coronary arterial distributions were also evaluated, but specific patterns of distribution did not correlate with morphology of the defect. Of 49 hearts with a normally aligned outlet septum, there were 24 perimembranous, 21 muscular, and 2 doubly committed and juxtaarterial defects. Two hearts had both perimembranous and muscular defects. Twelve of the 21 muscular defects were "central," being surrounded entirely by muscle and located just below the leaflets of the pulmonary valve, and 9 were located in the inlet or apical trabecular septum. There were 13 hearts with malalignment of the outlet septum, anteriorly in 11 and posteriorly in 2. All with anterior malalignment had a subpulmonary defect that was perimembranous in 7 and muscular in 4. Both defects with posterior malalignment had a subaortic perimembranous defect. Because variations in morphology of a ventricular septal defect have a direct impact on selection of the most suitable surgical repair, specific operative approaches are discussed.

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A characteristic feature of atrioventricular septal defects is a deficiency of the inlet part of the ventricular septum that results in a "scooped out" appearance. The depth of the scoop in relation to the disposition of the atrioventricular valves has been debated. To clarify the relation between the morphology of the ventricular septum and the disposition of the atrioventricular valves, we quantified these anatomic features in 151 hearts at autopsy to determine whether those features identified particular groups within the overall lesion. We found that 137 hearts had left atrioventricular valves with three leaflets. The left valve in the other 14 hearts exhibited a dual orifice, a two-leaflet or one-leaflet arrangement, or was imperforate. These anomalies could be analyzed in terms of a sequence of diminishing formation of the commissures. Also, three-leaflet valves displayed a variability in which the angular size of the mural leaflet correlated negatively with that of the inferior leaflet. In some of the hearts with a common atrioventricular orifice, the bridging leaflets did not meet over the ventricular septum, thus creating a "gap." The mural leaflet's angular size corresponded to a deficiency of the combined inferior-mural leaflet complex. Hearts with an abnormal disposition of the left atrioventricular valve had the ventricular septum "scooped" to a greater extent than those with a common orifice, although most had separate right and left atrioventricular orifices.

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The report describes the morphologic features of 102 specimens with hypoplasia of the chambers of the left heart, all with either a concordant atrioventricular connection (66 cases) or absence of the left atrioventricular connection, the right atrium being connected to a dominant right ventricle (36 cases). Either the aorta was connected to the left ventricle, having a patent valve in 23 cases and an imperforate valve in 5, or else the aortic trunk was atretic (74 cases). It was not possible to determine with certainty the ventricular origin of the aorta when its trunk was atretic, but in all hearts but 1 it seemed to be connected to the left ventricle. The atrial septum was intact in 11 hearts and grossly restrictive in a further 8. Deviation of the atrial septum relative to the infolded atrial roof (septum secundum) was seen in 32 specimens. The ventricular septum was intact in 88 hearts. The length of the left ventricle compared to the right was greatest in the 14 hearts with a ventricular septal defect. The left ventricular length was also significantly greater in hearts with a patent aortic valve. The state of the atrial septum, in contrast, bore no relationship to the dimensions of the left ventricle. Aortic coarctation was found in 44 of the hearts, and in all but 2 the shelf lesion was preductal in location. Coarctation was significantly more frequent in those hearts in which the ascending aorta was less than 3 mm in diameter. The anatomic findings are discussed in relation to recent advances in the surgical palliation of these malformations.

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Division of the morphologically left atrium (cor triatriatum) is a recognized clinical and surgical entity. Division of the right atrium (prominence of the eustachian and thebesian valves) is recognized pathologically, but is rare. It is unusual for this entity to be diagnosed during life. Stimulated by our experience with two patients seen at operation, one with an obstructive spinnaker-like formation and the other with a partitioned right atrium in the setting of pulmonary atresia, we reviewed the specimens in the heart museum of Children's Hospital of Pittsburgh that had prominence of the eustachian and thebesian valves. We identified 14 such hearts, which could be divided into two groups. In the first group, comprising six hearts, the valves were prominent in the form of Chiari networks and were of no functional significance. The valves were more extensive in the other eight hearts and partitioned the right atrium. In two of these, the valves themselves were the impediment to flow through the right side of the heart. In the other six, there was either atresia or severe stenosis along the right-sided pathways so that, after birth, the prominent valves retained their role during fetal life; namely, to deflect inferior caval venous return across the atrial septum to the left atrium. The partitions in these latter hearts would be of functional significance only if it were necessary to perform a Fontan procedure, when they might obstruct flow through an atriopulmonary (or atrioventricular) anastomosis.

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O perigo de lesao do feixe de conducao esta sempre presente na correcao cirurgica das cardiopatias congenitas. E um risco pequeno nos defeitos dos septos atrial e ventricular; ligeiramente maior na tetralogia de Fallot e nos defeitos do septo atrioventricular; tornando-se alto na transposicao das grandes arterias, nos coracoes com valvulas atrioventriculares cavalgadas e consideravelmente elevada na transposicao corrigida (com lesoes associadas) e na septacao dos coracoes com conexao atrioventricular univentricular.Com base na experiencia coletiva dos autores, os tecidos de conducao do coracao foram estudados na sua disposicao e trajetoria normais e tambem do modo como eles podem ser observados pelo cirurgiao nas varias cardiopatias congenitas. Com relativamente poucas regras a posicao e curso dos tecidos de conducao nos coracoes malformados, podem ser localizados e evitados o traumatismo e lesao dessas estruturas.Na experiencia dos autores a incidencia de disturbios da conducao e praticamente nula na correcao das cardiopatias simples e significativamente baixa nas lesoes complexas

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Nomenclature for congenital heart malformations has always been confusing. Efforts of classifying these malformations according to the relations and morphology of the cardiac segments have been attempted but have risen confusion because there many terms for the same malformations. In this paper we describe a well defined sequencial diagnosis that links the cardiac segments, and besides, permits the identification of the associated defects. The connections between the cardiac segments are considered has the most important step in the classification of heart malformations while, relations are left as a secondary stage in this study. In some congenital hearts malformations concordant or discordant atrioventricular connections do not apply as the univentricular hearts or ambiguus atrial situs, but we also stablish the parameters for their classification. In our opinion, this nomenclature describe in a complete and objective way the congenital heart malformation.

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