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Biomedical subjects

R H Anderson

Publications and source records attributed to R H Anderson.

At least 235 records · Page 13Linked to original sources
PubMed1993

Tricuspid atresia presenting in infancy. Survival and suitability for the Fontan operation.

BACKGROUND: The Fontan operation is the usual goal of therapy for children with tricuspid atresia. The influences of morphology and different management strategies on survival and subsequent suitability for this procedure are crucial but unstudied in an unselected population during the Fontan era. METHODS AND RESULTS: The fates of 237 consecutive infants with tricuspid atresia were reviewed (1972-1987; median follow-up, 8.0 years). Overall actuarial survival was 72% at 1 year, 53% at 5 years, and 46% at 10 years. Univariate risk factor analysis established that discordant ventriculoarterial connections (24% of the group; relative risk, 2.7), pulmonary atresia (14%, 2.3), aortic arch obstruction (7%, 2.9), and subaortic stenosis (8%, 4.2) were associated with poor survival, whereas pulmonary stenosis (60%, 0.52), balanced pulmonary blood flow (9%, 0.25), and older age at presentation (33%, 0.42) were beneficial. Multivariate analysis allowed the creation of predictive patient-specific survival curves and two additive indexes. Survival was worse for patients who underwent banding of the pulmonary trunk with aortic arch repair than for other individual palliative procedures (p < 0.001). On retrospective review, 204 patients (86%) were judged suitable for a future Fontan procedure at presentation. However, 99 (48%) of these are known to have died before a Fontan operation or became unsuitable for such surgery during follow-up, mostly because of death after palliative surgery (23 patients, 11%), sudden death (18 patients, 9%), and new adverse features (32 patients, 16%) such as subaortic stenosis, pulmonary arterial distortion, and ventricular dysfunction. CONCLUSIONS: Management in infancy must aim to ensure survival and maintain suitability for a Fontan-type operation. The accumulating incidence of adverse events with increasing age would argue in favor of undertaking definitive surgery in early childhood in most patients.

Cardiac Surgical Procedures↗
PubMed1993

Evidence for a distinct gap-junctional phenotype in ventricular conduction tissues of the developing and mature avian heart.

The gap-junctional proteins connexin43 and connexin42 have been shown to be expressed in the developing and mature avian heart, but their respective spatiotemporal distributions are unknown. In the present study, we have immunolocalized connexin42 in the conduction tissues of the adult avian heart (nonbranching bundle, bundle branches, and Purkinje fibers) and vascular endothelial cells. Connexin43 immunolabeling was confined to vascular smooth muscle. A novel microwave-based method was used to label connexin42 and connexin43 in the same tissue section. Neither connexin42 nor connexin43 was immunolocalized in working myocardium, atrioventricular node, and atrioventricular ring tissue of the bird heart. Although connexin42 first appeared in periarterial conduction myocytes and vascular endothelium at 9-10 embryonic days, the central conduction tissues, including the nonbranching bundle and proximal branches, remained immunonegative for connexin42 up until hatching (approximately 20 embryonic days). During the early postnatal period (1-14 days), connexin42 immunolabeling progressively spread up the bundle branches toward the nonbranching bundle. Connexin42 appeared uniformly distributed along the left bundle branch by 14 postnatal days. The distribution and spread of connexin42 immunoreactivity suggest that the emergence of specialized junctional contacts along ventricular fascicles occurs relatively late in heart development and coincides with the emergence of the chick from incubation within the egg.

Age Factors↗
PubMed1993

Obstruction of the left ventricular outflow tract: anatomical observations and surgical implications.

Obstruction within the outflow tract from the left ventricle can take several anatomic forms. To understand better these substrates, we reviewed the anatomy in the normal heart and, with this background, focused on the malformations observed at each level of the outflow tract which produce stenosis. We examined 75 malformed hearts and reviewed the literature pertinent to surgical aspects of obstruction. Close study of the normal aortic valve shows the lack of any discrete fibrous structure which can be described in terms of a ring-like annulus. The semilunar attachment of the leaflets makes a crown-shaped arrangement at the ventriculo-arterial junction rather than a strict ring. In the pathological study, valvar abnormalities were found in 45 cases. The valve had three leaflets in 20 cases, two leaflets in 24 cases and one leaflet in to the other. In two cases, additional obstruction was found at the sinutubular junction. Subvalvar stenosis was found in 30 hearts, the aortic valve being trifoliate in 28 and bifoliate in 2. The main substrate of subvalvar obstruction was posterior malalignament of the outlet septum (40%), followed by muscular septal hypertrophy (23%); obstruction was also an intrinsic feature in association with atrioventricular septal defects (14%). Although rare in our material, it can also be due to a fibrous or fibromuscular shelf. In our review of the literature, we have highlighted the various forms of valvar malformation and commented on the surgical options. Clear analysis of both the level of obstruction, and its precise anatomic substrate are essential for optimal surgical intervention.

Adolescent↗
PubMed1992

Morphology of the posterior junctional area in atrioventricular septal defects.

The location and size of the coronary sinus in hearts with atrioventricular septal defect were investigated in relation to the known disposition of the atrioventricular conduction axis. We examined the morphology in 40 hearts and supplemented this series with two other hearts that had been serially sectioned previously. The coronary sinus received drainage from a persistent left superior caval vein in 5 hearts. Six cases of 40 had malalignment of the septal structures relative to the crux of the heart. In these, the conduction axis was anticipated to course in the position where the inlet ventricular septum met the atrioventricular junction. The coronary sinus terminated in the left atrium in 4 hearts: 2 in the morphological series and 2 that were sectioned for histological studies. The sectioned hearts showed the atrioventricular conduction axis in the usual position for the defect, unrelated to the coronary sinus. The principle that the node and penetrating bundle are located at the intersection of the ventricular septum with the atrioventricular junction holds good despite the variability of the coronary sinus.

Adolescent↗
PubMed1992

Disposition of the atrioventricular conduction tissues in the heart with isomerism of the atrial appendages: its relation to congenital complete heart block.

OBJECTIVES: Our goal was to compare histologically the mechanisms producing congenital complete heart block in normally structured hearts and in hearts with isomerism of the atrial appendages. BACKGROUND: It is known that several different histologic patterns can underscore the existence of congenital complete heart block in the normally structured heart, and that block is particularly frequent in the setting of isomerism of the atrial appendages. The histologic findings in the latter setting were compared and contrasted with those found in the normally structured heart. METHODS: Serial section techniques were used to study 14 hearts with isomerism of the atrial appendage (12 with left isomerism and 2 with right isomerism) and 7 normally structured hearts. RESULTS: Discontinuity between the atrioventricular (AV) node and the ventricular conduction tissues was found in 10 of the 12 hearts with left isomerism; the other 2 hearts had a normally formed conduction axis and heart block was not present in these cases. In both hearts with right isomerism, "slings" of ventricular conduction tissue connected dual AV nodes; congenital complete heart block was not present in either case. In six of the seven cases with a normally structured heart, anti-Ro antibodies had been found in the maternal serum. All six of these hearts had discontinuity between the atrial tissues and the ventricular conduction axis. Intraventricular discontinuity was found in the seventh case, in which anti-Ro antibodies were not found in the mother. CONCLUSIONS: The pattern of congenital complete heart block in cases with left isomerism is discontinuity between the AV node and the conduction axis, in contrast to the pattern of atrial-axis discontinuity produced in the normally structured heart when anti-Ro antibodies are found in the maternal serum.

Abnormalities, Multiple↗
PubMed1992

The surgical anatomy of ventricular septal defect.

There is still no consensus as to how best to categorize and describe interventricular communications. In a series of three reviews, a system will be described showing how the anatomical criteria chosen for categorization will also serve as a guide for surgeons as to the location of the axis responsible for atrioventricular conduction tissue. In this first review, the defects described are not complicated by overriding of arterial or atrioventricular valves and are present in hearts that have basically normal segmental connections, or have some discordant connections (complete transposition or congenitally corrected transposition). The rims of the defect categorize the boundaries to which a surgeon may place a patch. Variations in these rims produce three classes of defect: perimembranous; muscular; and doubly committed and juxtaarterial (subarterial). The second part of the classification recognizes the further variation existing with respect to the component of the morphologically right ventricle into which the defect predominantly empties. Deficient atrioventricular septation can also lead to interventricular shunting in isolation, but the morphology is then quite different from hearts with simple deficiencies of the ventricular septum. We emphasize the abnormal location of the atrioventricular node in hearts with atrioventricular, as opposed to ventricular, septal defects.

Endocardial Cushion Defects↗
PubMed1992

Surgical significance of morphological variations in the atrial septum in atrioventricular septal defect for determination of the site of penetration of the atrioventricular conduction axis.

The morphological variation in the recognized landmarks for the atrioventricular conduction system was studied grossly in 94 hearts with atrioventricular septal defect, assessing 20 hearts with normal atrioventricular septation as a control. In all the hearts with intact atrioventricular septal structures, the tendon of Todaro demarcated the superior boundary of the triangle of Koch. In hearts with atrioventricular septal defect, however, the landmarks for the conduction axis made up a separate nodal triangle. The tendon of Todaro, along with a bridging tendon not found in the normal heart, were variably developed in hearts with atrioventricular septal defect and formed a further triangle unrelated to the axis for atrioventricular conduction. The opening of the coronary sinus was also variable in its location and size. It was the location of the inferior bridging leaflet as it crossed the ventricular septum that was the best surgical landmark to the site of penetration of the atrioventricular conduction axis.

Atrioventricular Node↗
PubMed1992

Morphological study of defects of the atrial septum within the oval fossa: implications for transcatheter closure of left-to-right shunt.

OBJECTIVE: To determine the anatomical variability of the oval fossa in cases of atrial septal defect and to find out which factors might make such defects suitable or unsuitable for closure by umbrella or clamshell devices. DESIGN: 100 specimens with defects of the atrial septum within the oval fossa were studied, especially the position of the defects within the fossa; the area of the defect in relation to the total area of the oval fossa; the shape of the rims and flap valve of the oval fossa; and the anatomical variability in the eustachian and thebesian valves. RESULTS: The oval fossa was displaced to the mouth of the inferior caval vein in four cases; displaced to the mouth of superior caval vein in two cases; placed on the middle of the interatrial wall in 43; or placed slightly towards the inferior caval vein in 51. Because of their shape 29 of the hearts were considered to be unsuitable for transcatheter closure of the defect. This was because the defect was too large (16 hearts); the oval fossa was displaced to the mouth of the inferior caval vein (four hearts) or to the superior caval vein (two hearts); lacked its anterior rim (two hearts); lacked the posteroinferior rim (one heart); because a thick eustachian valve was displaced posteriorly forming a false posteroinferior rim (one heart); or because the strand of insertion of the floor of the oval fossa was too distant from the left atrial aspect (three hearts). CONCLUSION: 68 hearts appeared to be ideal candidates for transcatheter closure; 3 would probably have been suitable; but 29 were unsuitable. These morphological variations might explain why the procedure has been unsuccessful in so many cases. Patients should be screened before any attempt is made at transcatheter closure.

Adolescent↗
PubMed1992

Correlation between echocardiographic and morphological investigations of lesions of the tricuspid valve diagnosed during fetal life.

OBJECTIVE: To assess the degree of agreement between the fetal echocardiographic and postmortem examination of hearts from fetuses with severe malformations of the tricuspid valve. DESIGN: A retrospective study to analyse echocardiographic recordings and make comparisons with postmortem findings. SETTING: Tertiary referral centre for fetal echocardiography. Institute for cardiac morphology. PATIENTS: 19 cases shown to have severe malformation of the tricuspid valve by fetal echocardiography that died in the prenatal or neonatal period. MAIN OUTCOME MEASURES: Correlations between morphology and measurements made at echocardiography and necropsy. RESULTS: The echocardiographic diagnosis was Ebstein's malformation in seven and tricuspid valvar dysplasia in 12 fetuses. These findings were confirmed in six and eight cases at necropsy. In one false positive diagnosis of Ebstein's malformation, necropsy showed dysplasia of the leaflets of the tricuspid valve without displacement. In four cases with the echocardiographic diagnosis of valvar dysplasia, necropsy showed displacement, the hallmark of Ebstein's malformation. Associated malformations that are known to worsen prognosis were predicted correctly by echocardiography. Taking the mean duration of four weeks between echocardiographic and postmortem investigations, both methods showed cardiomegaly causing lung hypoplasia, right atrial dilatation, and relative hypoplasia of the pulmonary trunk, morphometric factors that may be responsible for the poor outcome. Mostly good agreement existed between the echocardiographic and postmortem measurements if cases with an interval of more than eight weeks between the measurements were excluded. CONCLUSION: Fetal echocardiography was proved to be a reliable technique in differentiating the variants of tricuspid valvar disease, in diagnosing associated cardiac lesions, and in predicting quantitative factors that can define the subsequent outcome.

Ebstein Anomaly↗
PubMed1992

Abnormal laterality and congenital cardiac anomalies. Relations of visceral and cardiac morphologies in the iv/iv mouse.

BACKGROUND: In the management of hearts with deranged laterality, it is essential that the left and right atrial chambers are correctly identified. There are two major approaches, which are based on venous connections or on the morphology of the atrial appendages, and there is no consensus as to which is the most useful. We used the iv/iv mouse mutant, which is known to be pertinent to this problem, to evaluate the relations of cardiac defects with atrial, venous, and other visceral morphologies. METHODS AND RESULTS: The morphology of the heart and other organs was examined in 275 iv/iv mice using criteria based on abnormal laterality in humans. The arrangement of the atrial appendages was determined by morphological examination of the junction between the appendage and the venous component of the atrium. On this basis, 45.1% of cases were shown to have usual atrial arrangement, 50.2% had mirror imagery, 1.5% had right isomerism, and 3.3% had left isomerism. Every case of atrial isomerism had a cardiac lesion; the morphological types were similar to those seen in human cases. Of cases with either usual or mirror-image arrangement of the appendages, 33.2% had abnormal spleens, but only 3.1% had cardiac defects. Similarly, venous abnormalities were much more common (30.1%) than cardiac defects. CONCLUSIONS: Study results endorse the importance of the morphology of atrial appendages in predicting cardiac abnormalities and point to the marked inconsistency of the arrangement of other organs, including the spleen and the connections of the systemic veins.

Animals↗
PubMed1992

New findings concerning ventricular septation in the human heart. Implications for maldevelopment.

BACKGROUND: The mechanics involved in development of the inlet component of the morphologically right ventricle are, as yet, undecided. Some argue that this component is derived from the descending limb of the ventricular loop, and that the inlet and apical trabecular components of the muscular ventricular septum have separate developmental origins. Others state that the entirety of the right ventricle grows from the ascending limb of the loop, and that the muscular septum, apart from its outer component, has a unitary origin. We now have material from human embryos at our disposal, which, we believe, solves this conundrum. METHODS AND RESULTS: We used a monoclonal antibody against an antigen to neural tissue from the chick to demarcate a ring of cells separating the descending (inlet) and ascending (outlet) limbs of the developing ventricular loop of the human heart. Preparation of serial sections of graded human embryos enabled us to trace the fate of this ring, and hence the formation of the inlet of the right ventricle, to the completion of cardiac septation. Eight embryos were studied, encompassing stages 14-23 of the Carnegie classification. The ring of cells initially separating the ascending and descending limbs of the ventricular loop were, at the conclusion of ventricular septation, located within the atrioventricular junction, sequestrated for the most part in the terminal segment of atrial myocardium. CONCLUSIONS: Our study conclusively shows that the inlet component of the morphologically right ventricle is derived from the ascending limb of the embryonic ventricular loop, and that the inlet and apical trabecular components of the muscular septum are derived from the same primary ventricular septum.

Antibodies, Monoclonal↗
PubMed1992

Morphology of ventricular septal defects in complete transposition. Surgical implications.

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.

Abnormalities, Multiple↗
PubMed1992

Morphology of the ventriculoaortic junction in critical aortic stenosis. Implications for hemodynamic function and clinical management.

The clinical presentation of infants with critical aortic stenosis, as well as the results of surgical treatment, differs from obstruction of the left ventricular outflow tract in older children. To investigate a possible anatomic basis for this situation, we performed a detailed morphometric study of 21 hearts from infants who had critical aortic stenosis and 11 normal hearts from infants less than 3 months of age. In each of the hearts with critical aortic stenosis, only one commissure extended to the sinutubular ridge. The other two commissures were represented by folds in the aortic wall that suspended the leaflet below the level of the sinutubular junction. The leaflet thus had a free edge shorter than the circumference of the sinus, in contrast with the normal valve, in which leaflets always were longer than the circumference of their supporting sinus. Analysis of the fibrous triangles on the ventricular aspect of abnormal valves showed a symmetric three-sinus arrangement. In all but one specimen, however, only the triangle related to the mitral valve was fully developed. Although incision of both rudimentary commissures to the aortic wall should achieve some relief of obstruction, these morphologic features strongly mitigate against surgical restoration of normal function or growth in aortic valves having the morphology observed in this series of hearts.

Aortic Valve↗