Search PubMed⌕ Search

Biomedical subjects

R H Anderson

Publications and source records attributed to R H Anderson.

At least 217 records · Page 12Linked to original sources
PubMed1994

Clinical anatomy of the atrioventricular junctions.

OBJECTIVES: This study reevaluated the anatomy of the areas anterior and posterior to the atrioventricular (AV) septal structures, previously said to represent anterior and posterior septal areas. BACKGROUND: In descriptions of the locations of accessory AV pathways within the AV junctions, four regions have been recognized: the left and right free walls and the anterior and posterior septums. On the basis of known facts concerning cardiac structure, it is questionable whether these so-called septums are truly septal. METHODS: Ten human hearts were dissected to elucidate the clinical anatomy of these purportedly septal regions, together with the overall arrangement of the AV junctions. RESULTS: The true septal components of the AV junctions are the muscular and membranous AV septal areas. These separate the cavity of the right atrium from that of the left ventricle. The region previously designated as the anterior septum is part of the right parietal junction. It is contiguous with the membranous part of the septum but extends anteriorly and laterally from the septum as part of the supraventricular crest of the right ventricle ("crista supraventricularis"). In the region posterior to and beneath the mouth of the coronary sinus, only the most anterior extent, in continuity with the central fibrous body, is part of the muscular AV septum. The posterior extent of this area roofs over the diverging right and left ventricular walls and is filled in with fibroareolar tissue of the AV groove. CONCLUSIONS: The larger part of the regions anterior and posterior to the true AV septal areas are not septal but are parts of the parietal AV junctions. An understanding of these anatomic relations is essential for those wishing to modify conduction across the AV junctions.

Atrioventricular Node↗
PubMed1994

Prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus.

OBJECTIVE: This report describes our experience with fetal congenital heart disease since 1980. BACKGROUND: Knowledge and expertise in the diagnosis, management and natural history of fetal congenital heart disease is increasingly demanded by both obstetricians and parents. The analysis of a large series should help the pediatric cardiologist to provide this service. METHODS: The notes of 1,006 patients, where a prospective diagnosis of fetal congenital heart disease was made, were reviewed. The reason for referral, the diagnosis made, the accuracy of diagnosis, the fetal karyotype and the outcome of the pregnancy were noted. The cases were grouped into malformation categories, and the spectrum of disease seen was compared with that found in infants. RESULTS: Most fetal cardiac anomalies are now suspected by the ultrasonographer during obstetric scanning. A different incidence of abnormalities is seen compared with that expected in infants. Chromosomal anomalies were more frequent in the fetus than in live births. The accuracy of diagnosis was good. The survival rate after diagnosis was poor because of frequent parental choice to interrupt pregnancy and the complexity of disease. CONCLUSIONS: A large experience with fetal congenital heart disease allows the spectrum of disease to be described with accuracy and compared with that in infancy. Knowledge of the natural history of heart malformations when they present in the fetus allows accurate counseling to be offered to the parents. If the trend in parental decisions found in this series continues, a smaller number of infants and children with complex cardiac lesions will present in postnatal life.

Female↗
PubMed1994

Human endocardial innervation and its relationship to the endothelium: an immunohistochemical, histochemical, and quantitative study.

OBJECTIVE: The endocardium contains an extensive neural plexus, the composition and function of which are unclear. The aim of this study was to characterise the innervation of the endocardium in terms of the relative density and distribution of its autonomic and sensory nerve subpopulations and to assess the relationship between these nerves and endocardial endothelial cells. METHODS: Immunohistochemical, histochemical, confocal, and quantitative image processing techniques were applied to whole mount preparations of human postmortem endocardium obtained within 24 h of death. RESULTS: The overall distribution of nerve fibres and fascicles was demonstrated using antisera to the general neural marker protein gene product 9.5 (PGP 9.5). Nerves displaying acetylcholinesterase activity represented the main nerve subpopulation, occupying 9-18% of the quantified field area. Neuropeptide Y immunoreactive nerves formed the most numerous peptide containing nerve subpopulation identified, occupying 5-19% and 2-7% of the field area in the ventricle and atrial endocardium respectively and having similar distribution patterns to tyrosine hydroxylase immunoreactive nerves. Nerves showing immunoreactivity for somatostatin, vasoactive intestinal polypeptide, and substance P were detected at a lower density, occurred more frequently in the ventricular than atrial endocardium, and showed a similar distribution in the right and left sides of the heart. Combined peptide immunofluorescence and acetylcholinesterase staining, of the same preparation, indicated that putative sympathetic and sensory nerve subpopulations could be distinguished from presumed parasympathetic, acetylcholinesterase positive, nerves. The relationship between immunostained nerves and endothelial cells was assessed using confocal microscopy. Varicose nerve fibres were detected within 0.2 micron of overlying endothelial cells in the right ventricle and between 0.4-0.6 micron in the left ventricle. CONCLUSIONS: The heterogeneous population of nerve fibres demonstrated in the human endocardium may influence the known interaction between endocardial endothelial cells and the myocardium.

Adolescent↗
PubMed1994

The Wolff-Parkinson-White syndrome: the cellular substrate for conduction in the accessory atrioventricular pathway.

The longstanding quest for the anatomical basis of the Wolff-Parkinson-White syndrome has left many unanswered questions. The ultrastructural morphology of the myocytes comprising accessory atrioventricular pathways, which are capable of rapid and variable conduction, is central to understanding the development and behaviour of this congenital anomaly, but remains unknown. Examination of three surgically resected pathways was performed to determine their underlying cellular morphology and the pattern of intercellular coupling, by correlative light microscopy, electron microscopy and confocal scanning laser microscopy combined with immunohistochemical localization of the cardiac gap-junctional protein, connexin43. Two left-sided pathways were composed of myocardium of 'normal working ventricular' type. The right-sided pathway was composed almost entirely of highly abnormal myocytes characterized by aberrant myofibril organisation, with a lack of A-band material and abnormal mitochondria, but normal intact intercalated disks no different from those seen in left-sided pathways. The gap junctions of all pathways were composed of connexin43 distributed as in ventricular myocardium, and not as found in atrial or atrioventricular nodal tissues. While myocytes of abnormal structure were present in one of the accessory atrioventricular pathways examined, all pathways had morphologically normal gap junctions, the structures responsible for efficient intercellular coupling, with a pattern of distribution suggestive of working ventricular myocardium.

Adolescent↗
PubMed1994

The surgical anatomy of ventricular septal defects with univentricular atrioventricular connection.

Hearts that do not possess one-to-one connections at the segmental junctions almost always produce a univentricular atrioventricular connection. One ventricle is usually large and dominant and the other small, lacking one or two of its components. The ventricular septal deficiency forms part of the circulatory pathway. We take the stance that only hearts that possess a truly solitary ventricular chamber are univentricular. They cannot have a ventricular septal defect, and so are excluded from this study. This review, therefore, is concerned with the morphology of septal defects in hearts in which both atrioventricular junctions are connected exclusively to a dominant left or a dominant right ventricle, and those lacking one atrioventricular connection, where the remaining valve is connected to a dominant ventricle. This morphology in the absence of one atrioventricular connection can be modified when there is overriding of the solitary atrioventricular valve. The ventricular septal defects are analyzed and categorized for the various groups, and the position of the conduction axis is described for the well-recognized entities.

Heart Atria↗
PubMed1994

Innervation of the human cardiac conduction system. A quantitative immunohistochemical and histochemical study.

BACKGROUND: Cardiac conduction is influenced by peptidergic mechanisms as well as classic neurotransmitters. The distribution of peptide-containing nerves has not been well defined. METHODS AND RESULTS: Immunofluorescence and histochemical techniques were used to visualize the innervation of the human conduction system and to distinguish nerve subpopulations according to their peptide and enzyme content. Nerve fibers and fascicles displaying immunoreactivity for protein gene product 9.5 (PGP 9.5) were more numerous in the sinus and atrioventricular nodes than in the penetrating bundle, bundle branches, and adjacent myocardium. The relative density of innervation was greater in the central region of the sinus node than in the peripheral regions. Nerve densities were also higher in the transitional region of the atrioventricular node compared with its compact region. Acetylcholinesterase (AChE)-positive nerves were the main subtype identified in the sinus and atrioventricular nodes, representing half to two thirds of the stained area occupied by PGP 9.5-immunoreactive nerves. Neuropeptide Y-immunoreactive nerves represented the main peptide-containing subpopulation and occurred throughout the conduction system, displaying a similar pattern of distribution and relative density to those demonstrating tyrosine hydroxylase immunoreactivity. Nerve fibers showing immunoreactivity for vasoactive intestinal polypeptide, somatostatin, substance P, or calcitonin gene-related peptide exhibited distinct patterns of distribution and comprised a relatively minor component of the innervation, the percentage of stained area being 10- to 40-fold lower than that occupied by neuropeptide Y- and PGP 9.5-immunoreactive nerves, respectively. CONCLUSIONS: The innervation of human conduction tissues exhibits significant regional variation and comprises putative parasympathetic nerves and intrinsic neurons (AChE positive), sympathetic efferent nerves (neuropeptide Y- and tyrosine hydroxylase-immunoreactive nerves), and other peptide-containing nerves, some of which (substance P and calcitonin gene-related peptide containing) are considered to represent afferent nerves. Locally released peptides may be involved in the neural modulation of the human conduction system.

Acetylcholinesterase↗
PubMed1994

Atrioventricular conduction system in hearts with muscular ventricular septal defects in the setting of complete transposition.

The detailed structure of a ventricular septal defect was compared in 90 hearts with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections) and in 102 hearts with concordant connections at both junctions; the latter group was selected to include only cases with the septums aligned in the normal way. The interventricular communications observed in 13% of the group with complete transposition, which, in our material, had no counterpart in the hearts with concordant segmental connections, were of special interest. These defects, completely surrounded by muscle, were positioned around the midline on the right side of the septum but always lay under or partially under the septal leaflet of the tricuspid valve. The medial papillary muscle group was always to the "left hand margin" of the defect as seen by the surgeon. Because these defects lay within the boundaries set by the septal leaflet of the tricuspid valve, they would conform to the criteria for classification as inlet muscular defects but could equally be described as central or subtricuspid. It is significant that, in all those cases with histologic sectioning, the axis of atrioventricular conduction tissue ran to the surgeon's right hand margin. This position is markedly different from the pattern found in typical defects of the inlet septum, which are completely surrounded by muscle and extend to the posterior wall of the heart. In this more common situation, the conduction axis runs above the left hand margin of the defect. This finding has obvious implications for surgical treatment.

Heart Conduction System↗
PubMed1993

Echocardiographic and anatomic correlation of ventricular septal defect morphology in newborn Yucatan pigs.

With the use of a Yucatan micropig strain with a high incidence of ventricular septal defects (VSDs), results of two-dimensional and color-flow Doppler echocardiography of VSD morphology in newborn piglets were correlated with autopsy findings. A spectrum of perimembranous, muscular outlet, and doubly committed subarterial VSDs was found. Echocardiography was performed in 29 piglets weighing 1.2 to 4.4 (mean 2.8) kg, studied at age 4 to 18 (mean 8) days. VSD was diagnosed by means of echocardiography in 16 of 29 subjects; morphologic findings included perimembranous defects in 12, muscular outlet in two, and doubly committed subarterial defect in two. At autopsy the presence and location of defects were confirmed in all pigs. No additional defects were found. VSD diameters were 1.0 to 5.0 (mean 3.94) mm on echocardiography and 1.0 to 6.0 (mean 2.84) mm at autopsy. After aortic valve diameter was used as an internal control for tissue shrinkage during fixation, echocardiography/color Doppler imaging tended to overestimate VSD diameter by 21% (0.6 mm). In conclusion, echocardiography/Doppler imaging accurately identified the presence, morphology, and size of even the smallest VSDs in newborn Yucatan micropigs. Echocardiographic classification of VSD morphology in vivo will facilitate future research on specific types of VSDs in this animal model.

Animals↗
PubMed1993

Anomalous course of the left brachiocephalic vein.

An anomalous course of the left brachiocephalic vein beneath the aortic arch was identified in 7 patients undergoing surgical repair of congenital cardiac malformations. Six of these patients had the morphologic features of tetralogy of Fallot including severe obstruction to the right ventricular outflow tract and a right aortic arch. A review of the literature reveals this to be an uncommon anomaly. When it is present, however, it is frequently associated with a ventricular septal defect, obstruction of the right ventricular outflow, and aortic arch anomalies. This anomaly can be documented by echocardiography, at cardiac catheterization, or intraoperatively. The presence of a subaortic left brachiocephalic vein may have implications for the conduct of surgical procedures, especially in the setting of tetralogy of Fallot.

Abnormalities, Multiple↗
PubMed1993

Morphology of the cardiac conduction system in patients with electrophysiologically proven dual atrioventricular nodal pathways.

INTRODUCTION: Although the electrophysiologic criteria for dual atrioventricular nodal pathways are well established, the anatomical substrate is still unclear. METHODS AND RESULTS: We examined the hearts from 10 patients who had been studied electrophysiologically prior to cardiac transplantation. All 10 patients were male, aged 22 to 60 years. Nine of the 10 patients had dual atrioventricular nodal pathways according to accepted criteria. Histologic studies of the atrioventricular conduction system showed normal structure of the atrioventricular node in all 10 hearts, with minor variations within the node in 3 cases, within the penetrating bundle in 3 cases, and within the nonbranching bundle in 3 cases. The atrial approaches to the atrioventricular node were generally scanty in 6 hearts. The solitary case that was shown electrophysiologically to lack dual pathways had no obvious difference in the structure of the nodal area other than sparsity of transitional cells. We were unable to locate any extranodal atrial tracts as described by other investigators. CONCLUSION: The anatomical substrate for conduction over dual pathways may be too subtle to be detected by gross morphologic studies. Since dual pathways were unmasked in all patients but one during electrophysiologic studies, it may be that the potential for these pathways is ubiquitous.

Adult↗
PubMed1993

"AV nodal" reentry: Part I: "AV nodal" reentry revisited.

This review is the first of a two-part series of articles on "atrioventricular [AV] nodal reentry." The early clinical literature as well as the experimental studies are reviewed, and more recent morphologic data are presented, with the aim of clarifying whether the reentrant circuit is confined to the AV node, or consists in part of extranodal components. Most of the evidence supports the concept that atrial tissue is an essential link in the reentrant pathway. Arguments will be presented to indicate that within the AV node, the separation between antegrade and retrograde pathways is functional, not anatomical, and that both pathways are in electrotonic contact.

Animals↗
PubMed1993

The surgical anatomy of ventricular septal defects associated with overriding valvar orifices.

This is the second review in a three-part series concerned with the description and categorization of ventricular septal defects. By viewing the defects from the right ventricular aspect, they can be placed into one of three classes: perimembranous, muscular, or doubly committed and juxta-arterial. According to the posteroinferior margin of the third group, these could extend to become perimembranous or muscular. In this review, the complications produced by malalignment of the septal structures associated with overriding of an arterial or atrioventricular valve are described in detail. It shows that although there are problems in defining the extent of any interventricular communication, these ventricular septal defects can be classified with the same categorization as developed for those not associated with overriding. The nosology developed is able to serve as a guide to the surgeon to the site of the specialized axis for atrioventricular conduction.

Atrioventricular Node↗
PubMed1993

Dysplastic conditions of the right ventricular myocardium: Uhl's anomaly vs arrhythmogenic right ventricular dysplasia.

OBJECTIVE: Since 1905 there have been many reports of cases in which the right ventricle was deficient in myocardium. Several terms have been used to describe this condition. Of these, "Uhl's anomaly" and "arrhythmogenic right ventricular dysplasia" are most often used. Our study investigates the relation between these entities. METHOD: Five cases with a primary deficiency of the right ventricular musculature were examined. The findings were compared with those published reports to evaluate the similarities and differences between Uhl's anomaly and arrhythmogenic dysplasia. RESULTS: The five cases showed two patterns of myocardial deficiency in the right ventricle. On the one hand, the parietal wall was paper thin with complete absence of musculature and apposition of the endocardial and epicardial layers. On the other hand, patchy, localised fibrofatty tissue replacement was found within the parietal musculature. Evidence from our cases, combined with analysis of other publications, showed different modes and timing of clinical presentation of the patients with these two anatomical conditions, congestive heart failure or arrhythmia. CONCLUSIONS: The conditions variously described as Uhl's anomaly and arrhythmogenic dysplasia are separate and distinct morphological entities.

Adolescent↗
PubMed1993

Innervation of the human cardiac conduction system at birth.

OBJECTIVE: To study the pattern of innervation of the conduction system of the neonatal heart in humans. DESIGN: A prospective analysis based on immunohistochemical and enzyme histochemical examination of newborn human hearts. SETTING: A general district hospital. MAIN OUTCOME MEASURES: Fresh necropsy tissue. MATERIAL: Hearts of three neonatal humans with no cardiac anomaly, freshly taken at necropsy. METHODS: Serial sectioning to obtain a three dimensional reconstruction of the cardiac conduction system, followed by identification of the pattern of innervation by immunohistochemical and enzyme histochemical techniques; with a panel of antisera against protein gene product (PGP) 9.5 as a general neural indicator; dopamine beta-hydroxylase (DBH) and tyrosine hydroxylase (TH) as indicators for sympathetic neural tissue; and selected neuropeptides--namely, neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calcitonin gene related peptide (CGRP), and substance P (SP). Gomori's technique was used for locating cholinesterase activity. RESULTS: PGP immunoreactive (PGP-IR) nerves were present in large numbers in the sinus node, atrioventricular (AV) node, and penetrating atrioventricular bundle; in moderate numbers in the branching bundle; and occasionally in the bundle branches. Small numbers of DBH-IR and TH-IR nerves were seen in the sinus and AV nodes, mainly perivascularly; there were few in the penetrating and branching bundles and none in the bundle branches. A few perivascular NPY-IR nerves were seen only in the sinus node. VIP-IR, CGRP-IR, and SP-IR nerves were not seen. Pseudocholinesterase activity was found in the conduction tissue, whereas occasional acetylcholinesterase positive nerves were found only in the sinus and AV nodes. CONCLUSION: A considerable innervation of the human cardiac conduction system is present at birth, although, by comparison with the results of other studies on adult tissue, the mature pattern has not yet been established. Thus it is still in the process of maturation, especially with regard to the acquisition of various neurotransmitters, including the more recently described neuropeptides.

Calcitonin Gene-Related Peptide↗