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R H Anderson

Publications and source records attributed to R H Anderson.

At least 127 records · Page 7Linked to original sources
PubMed1998

Defective lateralisation in children with congenitally malformed hearts.

Defects in lateralization can be studied from the stance of populations, the individual, or the systems of organs within each individual. Unfortunately, and confusingly, the same terms are being applied to each of these situations, but inevitably with different meanings. Thus, there is presently no consensus on how we should use terms such as "heterotaxy" and "situs ambiguus". By far the least ambiguous use of these words is encountered when they are applied to the organs. In fact, each system of organs can accurately and simply be described in terms of its left-right morphology. All those organs which are paired then can be described, when interpreted on the basis of their intrinsic morphology, as being usually arranged, mirror-imaged, or as showing left or right isomerism. Within the heart, these changes are seen only in the atrial segment. The criterion for distinction of rightness or leftness within the atrial segment is the extent of the pectinate muscles relative to the atrioventricular junction. Application of this criterion permits unequivocal recognition of symmetry as opposed to lateralization. The same holds good for the other organs. Within any individual organ, therefore, the situation is neither ambiguous nor heterotaxic. Instead, it is lateralised or symmetrical. Within the individual, in contrast, there may well be discrepancies in the expected disposition of the systems of organs which produces potential ambiguity. To dispel this ambiguity, it is necessary to provide a full catalogue. For example, persons with otherwise normally arranged organs may have left bronchial isomerism. Other persons may have discordance between the thoracic organs, which are usually arranged, and the abdominal organs, which are mirror-imaged, but no evidence of isomerism. Within the population, however, we are unaware of any genetically or environmentally induced syndrome in which all individuals show evidence of mirror-imagery, or of isomerism, or of specific discordance between the systems. In fact, all known syndromes encompass all types of defective lateralization. When attempting to identify the genetic mechanisms for production of the syndromes, therefore, it could be positively misleading to attempt to separate isomerism from other perceived forms of"heterotaxy". Our preference is to consider any deviation from the usual arrangement as heterotaxy, and to specify the specific arrangement of the organs within each malformed individual.

Child↗
PubMed1998

Postmortem changes in the immunohistochemical demonstration of nerves in human ventricular myocardium.

In order to delineate the effects of death on the immunofluorescence of autonomic nerves supplying the human ventricular myocardium, we studied percutaneous myocardial samples obtained postmortem from 5 individuals within 3 h of death. Subsequent samples were obtained daily from the same individuals up to a total of 5-11 d. The antibodies employed included those against protein gene product 9.5 to demonstrate nervous tissue, dopamine beta-hydroxylase and tyrosine hydroxylase to reveal catecholaminergic neural tissue and neuropeptide Y. An indirect immunofluorescence technique using the avidin-biotin method was employed. The density of myocardial protein gene product 9.5 immunoreactive nerves declined on the 7th day, and became markedly diminished by the 11th day. Immunoreactive dopamine beta-hydroxylase nerves decreased on the 5th day, and were difficult to identify by the 9th day. The density of tyrosine hydroxylase and neuropeptide Y containing nerves rapidly diminished on the 3rd and 4th days, and became undetectable by the 7th and 8th days, respectively. The present results indicate that, depending on the type of antibodies used, immunohistochemical techniques can be used on human hearts obtained up to within 6 d of death to study cardiac innervation.

Aged↗
PubMed1998

Anatomy of the pig heart: comparisons with normal human cardiac structure.

Transgenic technology has potentially solved many of the immunological difficulties of using pig organs to support life in the human recipient. Nevertheless, other problems still remain. Knowledge of cardiac anatomy of the pig (Sus scrofa) is limited despite the general acceptance in the literature that it is similar to that of man. A qualitative analysis of porcine and human cardiac anatomy was achieved by gross examination and dissection of hearts with macrophotography. The porcine organ had a classic 'Valentine heart' shape, reflecting its location within the thorax and to the orientation of the pig's body (unguligrade stance). The human heart, in contrast, was trapezoidal in silhouette, reflecting man's orthograde posture. The morphologically right atrium of the pig was characterised by the tubular shape of its appendage (a feature observed on the left in the human heart). The porcine superior and inferior caval veins opened into the atrium at right angles to one another, whereas in man the orifices were directly in line. A prominent left azygous vein (comparable to the much reduced left superior caval or oblique vein in man) entered on the left side of the pig heart and drained via the coronary sinus. The porcine left atrium received only 2 pulmonary veins, whereas 4 orifices were generally observed in man. The sweep between the inlet and outlet components of the porcine right ventricle was less marked than in man, and a prominent muscular moderator band was situated in a much higher position within the porcine right ventricle compared with that of man. The apical components of both porcine ventricles possessed very coarse trabeculations, much broader than those observed in the human ventricles. In general, aortic-mitral fibrous continuity was reduced in the outlet component of the porcine left ventricle, with approximately two-thirds of the aortic valve being supported by left ventricular musculature. Several potentially significant differences exist between porcine and human hearts. It is important that these differences are considered as the arguments continue concerning the use of transgenic pig hearts for xenotransplantation.

Adult↗
PubMed1998

The architecture of the atrial musculature between the orifice of the inferior caval vein and the tricuspid valve: the anatomy of the isthmus.

INTRODUCTION: Electrophysiologists recognize a so-called "isthmus" in the right atrium through which passes the reentrant circuit of common atrial flutter. Ablative lesions placed in this narrow channel have proved effective in breaking the circuit. To the best of our knowledge, however, no study has been performed to establish the arrangement and orientation of the atrial myocardial fibers in this crucial area. METHODS AND RESULTS: We examined 28 normal heart specimens, identifying a quadrilateral area composed of three morphologic sectors between the inferior caval vein and the tricuspid valve confluent superiorly with the triangle of Koch. Within this quadrilateral, there are constant recesses, or sinuses, inferior and lateral to the orifice of the coronary sinus. The inferior isthmus measured an average of 31+/-4 mm (range 19 to 40). Gross examination identified marked differences in the atrial wall forming the quadrilateral. A smooth anterior component forming the vestibule of the tricuspid valve was found in all the hearts, but variations in the remaining sectors were seen in ten specimens. The usually membranous posterior sector was noticeably muscular in three specimens, while the middle, trabecular sector was more membranous in five specimens. We demonstrated the orientation of the subendocardial atrial fibers by dissection in 14 specimens, revealing a relatively constant overall pattern in eight specimens and variations in fiber orientation in the remaining specimens. CONCLUSION: There are considerable anatomic variations in the atrial wall that comprises the so-called isthmus. The presence of recesses and membranous areas in some hearts and the variations in arrangement of the subendocardial fibers are relevant in improving understanding of conduction in this area.

Data Interpretation, Statistical↗
PubMed1998

The architecture of the sinus node, the atrioventricular conduction axis, and the internodal atrial myocardium.

Concomitant with the development of catheter ablation techniques for the treatment of atrial arrhythmias, there is renewed interest in the morphologic arrangement of the cardiac conduction system. In this article, we revisit the anatomy of the specialized tissues, making special reference to the descriptions given at the time of their discovery. According to criteria for histologic distinction of morphologically specialized tracts set nearly 100 years ago, the penetrating bundle (of His) and the ventricular bundle branches are tracts of specialized cells encased by insulating sheaths of fibrous tissue. In contrast, the sinus and AV nodes are recognized histologically but are not insulated from the working atrial myocardium. At its distal extent, the AV node is distinguished from the penetrating bundle not so much by cellular characteristics, but by the presence of a fibrous collar that surrounds the specialized cells. At the atrial part, a zone of histologically transitional cells interposes between the compact node and the working atrial myocardium. Transitional cells enter the triangle of Koch to join the compact node from superiorly, inferiorly, posteriorly, and from the left. Transitional cells of the sinus node, in contrast, are limited to short tongues that interdigitate with musculature of the terminal crest. Apart from a variable extension of its tail, there are no prominent histologically discrete extensions from the sinus node into the working atrial musculature. The internodal myocardium does not contain discrete conducting tracts comparable with the ventricular bundle branches. Preferential conduction more likely reflects the arrangement of the working internodal cells and their related cellular properties.

Atrioventricular Node↗
PubMed1998

Mahaim pathway.

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Atrioventricular Node↗
PubMed1998

The structure of the common atrioventricular valve in hearts having isomeric atrial appendages and double inlet ventricle.

BACKGROUND AND AIMS OF THE STUDY: It is now well recognized that regurgitation through a common atrioventricular valve can compromise the clinical course both before and after surgical interventions in patients with visceral heterotaxy. This may reflect the anatomic structure of the valve. This study aimed to determine whether the structure of the common atrioventricular valve found in the setting of hearts with isomeric atrial appendages and double inlet ventricle differs from that of the valve guarding a common junction in hearts with biventricular atrioventricular connections. METHODS: Sixty-three autopsied hearts with double inlet ventricle and isomeric atrial appendages were studied, in addition to 79 with isomerism and biventricular atrioventricular connections, all having a common valve guarding the atrioventricular junctions. RESULTS: A valve with three or four leaflets was seen more frequently in hearts with double inlet ventricle than in those with biventricular atrioventricular connections (p = 0.016, chi-squared test). Complicated multiple orifices within the valvular curtain, including abnormal accessory orifices within a leaflet, were found in seven cases with double inlet to a dominant morphologically left or right ventricle. The presence of four papillary muscles was the most common pattern in hearts with double inlet ventricle. Straddling of the papillary muscles to a rudimentary and incomplete ventricle was seen in 23% of cases. Direct attachment of tendinous cords to the ventricular septum or parietal wall was seen 81% of hearts with double inlet. CONCLUSIONS: These features of the common valve found with double inlet atrioventricular connection seem less suited to function as the inlet valve supporting the systemic circulation. The recognized abnormal features should be identified preoperatively so as to plan more effective valvular plasty, or alternatively to establish different surgical strategies.

Abnormalities, Multiple↗
PubMed1997

Angiographic and morphologic features of the left ventricle in Ebstein's malformation.

Quantitative and qualitative cineangiographic analysis of the left ventricle (LV) was performed in 26 patients with isolated Ebstein's malformation, having a mean age of 23 +/- 17 years. Nine autopsied hearts with isolated Ebstein's malformation were submitted to morphologic and morphometric analysis. In 4 of the cases, it was possible to make a direct correlation between the angiographic data obtained during life and the autopsy findings. On the basis of the LV end-diastolic volume we identified 3 groups of patients: 7 with volume <60 ml/m2, another 7 with volume between 60 and 80 ml/m2, and 12 with volume >80 ml/m2. The LV ejection fraction was reduced in 2 patients with normal LV end-diastolic volume and in 6 with increased LV end-diastolic volume. The ratio of ventricular mass to LV end-diastolic volume was always adequate, but a reduction of the ventricular contractive performance (end-systolic pressure to end-systolic volume ratio <3 mm Hg/ml/m2) was found only in patients with a dilated left ventricle. No correlation was demonstrated between the extent of the atrialized component of the right ventricle (mean value 67 +/- 31 cm2, range 13 to 133) and the LV dimensions. All but 2 patients showed a leftward diastolic displacement of the ventricular septum, but in only 1 did this produce an elongated shape of the left ventricle. Sixteen had anomalies of LV dynamics: 10 with hypokinesia (3 of the posterior wall, 4 of the apex, 1 of the inferior wall, 1 of the septum, and 1 global), 6 with dyskinesia (1 of the posterior wall, 2 of the apex, 1 of the posterior wall and apex, 1 of the superior part of the septum, and 1 of the anterior wall), and 8 with premature diastolic distension of the anterobasal wall. Morphometric analysis produced mean values for myocytes of 59 +/- 10%, for the interstitium of 21 +/- 4%, and for fibrous tissue of 20 +/- 9% (normal 4 +/- 1%). Five autopsied hearts had a prolapsing and/or dysplastic mitral valve.

Adolescent↗
PubMed1997

Location of the coronary arterial orifices in the normal heart.

We examined the coronary arterial orifices in relation to the aortic valve to determine the range of normality in 23 normal hearts from autopsied adults. We determined the position of the zones of apposition between leaflets, the size of the leaflets, the number, position, and shape of the coronary arterial orifices, and their relation to the sinutubular junction. The aortic valve had three leaflets in all specimens, nearly equally spaced around the aorta. The left coronary artery arose within the left posterior aortic sinus (of Valsalva) in 16 (69%) specimens, above the sinutubular junction in five (22%), and at the level of the junction in two (9%). The distance of the left orifice from the zone of apposition between the left posterior and anterior aortic leaflets was between 13% and 61% of the width of the aortic sinus at the sinutubular junction. The right coronary artery arose within the anterior aortic sinus in 18 (78%) specimens, above the junction in three (13%), and at the level of the junction in two (9%). The distance of the orifice from the zone of apposition between the leaflets hinged from the anterior and right posterior aortic sinuses was between 5% and 62% of the width of the aortic sinus at the sinutubular junction. An accessory coronary orifice was found in the anterior aortic sinus in 17 (74%) specimens, whereas a third orifice in this sinus was found in five hearts. The coronary arterial orifices are usually located within the aortic sinuses below the sinutubular junction, but are rarely centrally located. Accessory coronary arterial orifices are found in the majority of the anterior aortic sinuses.

Adult↗
PubMed1997

Is there such a thing as the "tendon of the infundibulum" in the heart?

The fibrous skeleton of the heart has featured prominently in anatomical and surgical descriptions, although all its purported components are difficult to demonstrate. In descriptions of the skeleton, there have been repeated references to the presence of a tendon (or ligament) between the aortic and pulmonary roots. Such a tendon is rarely, if ever, discussed in the context of surgical procedures being carried out on the ventricular outflow tracts. Our study was undertaken, therefore, to investigate the existence and nature of such a tendon or ligament. Serial transverse sections were made through roots of aorta and pulmonary trunk in an intact fetal heart. In addition, ten normal adult hearts were dissected to display the components of the fibrous skeleton of the heart. No discrete fibrous or elastic structure could be detected in the tissue plane between the aortic sinuses and the subpulmonary muscular infundibulum, although a fascial strand was observed in one heart. Apart from this specimen, the space between the free-standing muscular subpulmonary infundibulum and the sinuses of aorta hearing the coronary arteries was occupied only by loose fibroareolar tissue. The initial presence of the ligament was described following studies of animal and macerated human hearts. Subsequently, it would seem its existence has been passed down through generations of morphologists and surgeons without its presence being reconfirmed. We have been unable to demonstrate any structure approximating to the initial illustrations.

Aortic Valve↗
PubMed1997

Anatomically sound, simplified approach to repair of "complete" atrioventricular septal defect.

BACKGROUND: There are few congenital anomalies of the heart that have benefited more from thorough anatomic analysis than the complex anomaly known as atrioventricular septal defect in the setting of common atrioventricular junction. Recent advances in understanding the anatomy of this lesion have led to alternative methods of repairing these defects. METHODS: The medical records of 21 consecutive patients undergoing repair of complete atrioventricular septal defect have been reviewed. Nine of these patients had a standard one- or two-patch repair, and 12 had direct closure of the ventricular element of the defect. RESULTS: Direct closure resulted in significantly shorter pump and cross-clamp times. Follow-up for an average of 34 months suggests that when direct closure can be performed, the results are comparable with those of the more standard technique. CONCLUSIONS: Our initial success with this approach is encouraging; however, longer follow-up is required to establish whether it will be broadly applicable.

Cardiac Surgical Procedures↗
PubMed1997

Cardiac morphology at late fetal stages in the mouse with trisomy 16: consequences for different formation of the atrioventricular junction when compared to humans with trisomy 21.

OBJECTIVE: The mouse with trisomy 16 (Ts16) is held to be a genetic model for humans with Down's syndrome (Ts21). Both trisomies are associated with atrioventricular septal defects, but the precise morphology in the mouse remains unclear. We have therefore characterised cardiac morphology in the mouse with Ts16. METHODS: Ts16 fetuses, from a Rb(11.16)2H/Rb(16.17)7Bnr x C57BL/6J cross, were collected on gestational days 17 or 18 (full term = 19 days) and studied using scanning electron microscopy and serial sections. RESULTS: The hearts showed a spectrum of deficient atrioventricular septation which we categorised into two types. In one, a common atrioventricular junction was separated into right and left orifices by a tongue of tissue joining two valvar leaflets that bridged the ventricular septum to varying extent. In the other, a common atrioventricular junction was connected exclusively to the left ventricle. All hearts had ostium primum atrial and ventricular septal defects, together with abnormal ventriculo-arterial connections. No heart had the typical morphology seen in the human with Down's syndrome, namely a balanced common atrioventricular junction, guarded by a common valve, with the aorta connected exclusively to the left ventricle. CONCLUSIONS: The cardiac defects seen in Ts16 mice show marked differences from the typical anatomy in human Ts21, suggesting more complex mechanisms of cardiac dysmorphogenesis in Ts16. The mouse model will prove valuable in elucidating the mechanism of normal expansion of the atrioventricular junctions, and help in charting the precise steps involved in atrial and ventricular septation.

Animals↗