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Biomedical subjects

R H Anderson

Publications and source records attributed to R H Anderson.

At least 325 records · Page 18Linked to original sources
PubMed1988

Thoughts on concepts of development of the heart in relation to the morphology of congenital malformations.

In the past, it has often been the case that congenital malformations have been categorized in terms of their presumed embryologic development. The knowledge of development, however, has itself often been derived from studies of the normal heart during its development coupled with inferences drawn from the morphology of the abnormal hearts. This can lead to circular thinking which, often, has little basis in fact. It is our belief that cardiac embryology is an important science which should stand in its own right, but that knowledge of abnormal development should be derived from observation rather than inference. The potential dangers of concepts derived by extrapolation are illustrated with reference to hearts having deficiencies of atrioventricular septation ('endocardial cushion defects') and those with double inlet left ventricle ('single ventricle'). It is shown that description of these hearts is greatly facilitated by eschewing those concepts derived from 'armchair embryology'. Once a clear description is established, the scene is set to understand the real mechanisms underscoring the maldevelopment of these lesions.

Endocardial Cushion Defects↗
PubMed1988

The significance of discontinuity between the aortic and mitral valves in the presence of "normally related" arterial trunks.

We describe a case in which an extensive sub-aortic infundibulum was accompanied by a muscular ventricular defect in the presence of a normal relationship of the great arteries. First impressions suggested that the ventriculo-arterial connexion was concordant, but sectioning the heart showed it to be double outlet from the right ventricle. It is important to identify this combination of features prior to attempted surgical correction, since the potentially restrictive sub-aortic infundibulum may not be visualised if the heart is approached surgically from the right ventricle. If unrelieved in the repair process, this could leave severe sub-aortic stenosis.

Aortic Valve↗
PubMed1988

Experimental ventricular hypertrophy in growing pigs.

An experimental model has been developed in the growing pig to study the pathology of myocardial hypertrophy. Aortopulmonary shunts were created in 4-week-old piglets and the animals were followed-up to 7 months of age. The pulmonary arterial pressure had increased at 4 weeks of shunt function by an average of 118% and the pulmonary blood flow by as much as 63%. In the longest living animal (7 months), the pulmonary arterial pressure and blood flow had increased by 170 and 53%, respectively, in relation to normal findings. The animals were killed at varying intervals and the hearts removed and examined. The weight of the entire hearts and their individual component parts increased significantly when compared with values found for normal postnatal development (P less than 0.001). The percentage increase in the total heart weights increased at all stages of development varying from an initial 109% to 39% at the time of killing. All the other parameters were also significantly greater than the values found for the normals, including the myocardial wall thickness in both ventricles (P less than 0.001). Histology showed changes comparable to gross myocardial wall thickness hypertrophy observed in human congenital anomalities. The method is recommended as a model for further studies on myocardial hypertrophy in growing individuals.

Animals↗
PubMed1988

Transluminal balloon dilation of resected coarcted segments of thoracic aorta: histological study and clinical implications.

The effect of experimental balloon dilation on seven excised specimens of classic coarctation was assessed histologically. Widening of the lumen was achieved in all specimens by tears in the vessel wall. The tears extended through the intima in one specimen and through both intimal and medial layers in six specimens. In view of the extent of wall damage, we postulate that there would be serious long-term complications following balloon dilation for the treatment of native coarctation.

Adult↗
PubMed1988

Common arterial trunk with pulmonary atresia.

We describe a congenitally malformed heart with usual atrial arrangement and concordant atrioventricular connexions in which a solitary arterial trunk left the base of the heart and supplied the coronary and systemic arteries. Pulmonary blood supply was derived from systemic to pulmonary collateral arteries but, in addition, hypoplastic intrapericardial pulmonary arteries were found in each lung hilum. The two sets of hilar arteries were discontinuous, but it seemed likely that this discontinuity had been artefactually produced by prior dissection. Irrespective of this matter, the left pulmonary arteries were connected by a thread-like atretic cord to the left-sided sinus of the solitary arterial trunk. This indicates that, initially, there had been a common trunk which now demonstrates pulmonary atresia. The significance of this lesion is discussed in the light of the nomenclature and description of hearts with common arterial trunk.

Heart Defects, Congenital↗
PubMed1988

Cineangiographic spectrum of Ebstein's malformation: its relevance to clinical presentation and outcome.

Eight heart specimens were examined that had concordant connections of the cardiac segments and exhibited Ebstein's malformation. The displacement of the leaflets of the tricuspid valve from the atrioventricular junction varied from minimal and isolated involvement of the septal leaflet to involvement of the mural and anterosuperior leaflets as well. This resulted in a wide range of physiologic "atrialization" of the right ventricle. The distal insertion of the valve leaflets also exhibited a spectrum of malformation. At one end the insertion was the normal focal variety, allowing free communication between the atrialized and functional parts of the right ventricle. At the other end there was abnormal linear attachment of the anterosuperior and mural leaflets to an anomalous muscular shelf at the junction between the inlet and apical trabecular portions of the right ventricle. The anteromedial commissure between the anterosuperior and the displaced septal leaflets provided a "keyhole" communication between the two ventricular compartments. Between these extremes were cases in which hyphenations along a locus of linear attachment allowed additional communications between the ventricular compartments. In light of these anatomic observations, cineangiograms of 26 patients with Ebstein's malformation were reviewed retrospectively. It was possible to classify the patients into three groups with focal, hyphenated and linear attachment, respectively. Size, ejection and displacement indexes of the functional right ventricle measured from the angiograms suggested that the severity of the malformation increased from focal attachment through hyphenated to linear attachment. Clinical observations relative to symptoms (cyanosis at rest, reduced exercise tolerance) and outcome supported this morphologic-angiographic grading.

Child↗
PubMed1988

The cross sectional anatomy of ventricular septal defects: a reappraisal.

The cross sectional echocardiographic description of holes in the ventricular septum has been unsatisfactory, chiefly because there are so many classifications of this defect. The accurate description of the anatomy of individual defects, from cross sectional images, is more important than attempts to fit them into a preconceived classification. One hundred specimens of hearts with a ventricular septal defect were reviewed to identify those features that are of value in the interpretation of cross sectional images. Three groups of defect were identified: those which abutted the central fibrous body, those with a margin partly formed by an area of fibrous continuity between the leaflets of the aortic and pulmonary valves, and those with entirely muscular margins. Each group had features that were readily discernible in cross section. Other features of the defects seen in the cross sectional images identified defects that opened between the two ventricular inlets, defects that opened between the two subarterial outlets, and those that extended solely into the trabecular septum. The criteria for describing the anatomy of defects were established in hearts with normal connections, but they were found to be equally applicable in hearts with discordant atrioventricular connection, discordant ventriculoarterial connection, common arterial trunk, and double outlet from the morphologically right ventricle. Cross sectional imaging, by echocardiography and potentially by other techniques, provided a uniquely detailed and precise description of the morphology of ventricular septal defects.

Abnormalities, Multiple↗
PubMed1988

Atrioventricular septal defect in prenatal life.

In a series of more than 3500 pregnancies referred for fetal echocardiography, 29 cases of atrioventricular septal defect were detected in the fetus. There was a chromosomal anomaly in 14 of these cases, left atrial isomerism in 12, and right atrial isomerism in two. Complete heart block was found in 11 of the cases with left atrial isomerism. Many associated cardiac abnormalities were found, particularly in the fetuses with atrial isomerism; the most common were double outlet right ventricle or aortic arch anomalies. The prognosis was poor in all patients with atrioventricular septal defect detected prenatally. Fifteen pregnancies went to term but there are only four survivors. Two of those have trisomy 21, a further patient has inoperable defects, and only one remains well and is awaiting corrective surgery for a partial atrioventricular septal defect.

Abnormalities, Multiple↗
PubMed1988

Coarctation of the aorta in prenatal life: an echocardiographic, anatomical, and functional study.

In a prospective echocardiographic study of over 2000 pregnancies, 24 fetuses were found to have dilatation of the right ventricle and pulmonary artery when these structures were compared with those of the left heart. In 18 of these cases the diagnosis of coarctation or interruption of the aorta was correctly inferred from these findings. On direct echocardiographic examination of the aortic arch, arch hypoplasia or interruption of the aortic arch was recognisable prenatally in 10 of these 18 cases, most readily between 20-30 weeks' gestation. In 11 of 12 cases of aortic arch anomaly studied by Doppler echocardiography, a reduction in blood flow in the ascending aorta was demonstrated. The intracardiac appearances were suggestive of coarctation but the Doppler findings were within normal limits in two further cases which later proved to be normal. A diaphragmatic hernia was found in four fetuses and the intracardiac echocardiography and Doppler findings were the same as those found in fetuses with aortic coarctation. Five cases of coarctation were overlooked on the prenatal echocardiogram but these were found at follow up of the infants. Thus coarctation of the aorta can be diagnosed prenatally, although the condition may be missed or incorrectly predicted by the criteria examined in the present study. Reduced aortic blood flow is a demonstrable feature of aortic arch abnormalities but it is found in other conditions that are not associated with coarctation.

Aorta↗
PubMed1988

Intermediate to late term results of Mustard's procedure for complete transposition of the great arteries with an intact ventricular septum.

Overall survival after Mustard's operation was assessed in 130 patients with complete transposition of the great arteries and an intact ventricular septum who were operated on at the Brompton Hospital in the 12 year period from January 1974 to December 1985. Actuarial analysis showed a survival at five years of 79.1% (25 deaths in 130 patients). Half the deaths occurred within a month of operation and half up to five years later. Operation under the age of three months carried a greater mortality (six deaths in 11 patients). Statistical analysis showed that these survival figures were consistent throughout the series and did not alter with the year of operation. In the light of recent trends in treatment of this lesion, it is concluded that for neonates an arterial switch procedure is now likely to carry the best chance of long term success. For the patient who presents after the age of three months, however, there may still be a place for the Mustard procedure.

Age Factors↗
PubMed1988

Doubly committed subarterial ventricular septal defect: new morphological criteria with echocardiographic and angiocardiographic correlation.

To gain a better understanding of the anatomy of doubly committed subarterial defects and its relation to findings at cross sectional echocardiography and angiocardiography, eight necropsy specimens from patients with this condition were examined, and preoperative echocardiograms and angiocardiograms from 313 patients with surgically or necropsy confirmed outlet defect were reviewed. Of these, 48 had doubly committed subarterial defects. Morphological review showed that doubly committed defects are roofed by the arterial valves in fibrous continuity because of lack of both the outlet septum and the "septal" aspect of the subpulmonary infundibulum. Angiocardiography had a lower sensitivity (50%) than echocardiography (95%) for diagnosis of doubly committed defects, but each was highly specific. In five (14%) of 35 available echocardiograms the arterial valves were normally offset, but in the remainder they were at the same level. The ventriculoarterial connection was concordant in 37/48 (77%), discordant in five (10%) of 48, and double outlet right ventricle in six (13%) of 48. Displacement of the fibrous raphe between the arterial valves in relation to the ventricular septum below was associated with outflow obstruction in 14 patients (pulmonary in nine and aortic in five). These features were readily identified by echocardiography. Thus echocardiography is not only a more accurate method than angiocardiography of recognising these defects, but also shows that the arterial pole of the heart is architecturally abnormal.

Angiocardiography↗
PubMed1988

A histological study of the atrioventricular junction in hearts with normal and prolapsed leaflets of the mitral valve.

The mitral annulus is the point at which the atrial and ventricular walls meet the base of the mitral valve cusps. The suggestion that a variant of this arrangement termed "disjunction" was associated with prolapse of the leaflets prompted examination of the mitral atrioventricular junctions in seven normal hearts and six with prolapse owing to floppy mitral valves. A complete cord-like ring of connective tissue that encircled the atrioventricular junction and into which the three components were inserted at the same point was found in only one heart. The remaining hearts all showed a mixture of segments in which either the three components were inserted into a cord or simply met. Disjunction, defined as a separation of the atrial wall-mitral valve junction from the other component, the left ventricular wall, can occur both with and without a cord-like annulus. There was no significant difference in the number of segments around the left atrioventricular junction which showed disjunction in hearts with normal or prolapsing leaflets. The feature termed disjunction is an anatomical variation of the normal morphological characteristics of the left atrioventricular junction.

Aged↗