Straddling and overriding atrioventricular valves: morphology and classification.
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Heart Conduction System↗
Biomedical subjects
S Y Ho
Publications and source records attributed to S Y Ho.
Location and vascular supply of sinus node in human heart.
The exact location of the sinus node was determined in 25 infant hearts using reconstructive techniques. The sinus node was found to lie on the lateral aspect of the superior cavo-atrial junction in the great majority (22 hearts). In only 3 hearts was it found to straddle the summit of the crest of the right atrial appendage where it is popularly believed to be located. In the majority of instances a single artery supplied the node (in 11 hearts the artery approached posteriorly, and in 10 the artery approached anteriorly), though there was considerable variation in the exact anatomy of the arterial supply. Connections between the sinus node and atrial myocardium were diffuse and abundant but in no instances were tracts of specialised cells observed leaving the node and traversing any distance through the atrial wall. These findings are relevant to the sinus node dysfunction that may follow cardiac surgical procedures.
Arteries↗
Disposition of the sinus node in left-sided juxtaposition of the atrial appendages.
In view of the complex cardiac anomalies frequently associated with left-sided juxtaposition of the atrial appendages the disposition of the sinus node has been studied in 6 of these hearts. While the sulcus terminalis still provides a landmark to the position of the node, the nodes were in an anterior position in all 5 hearts with complete juxtaposition, 2 being inferior to the crista terminalis. The node was in a more normal, lateral position in the sixth case with partial juxtaposition.
Heart Atria↗
Coarctation, tubular hypoplasia, and the ductus arteriosus. Histological study of 35 specimens.
A histological study has been made in an attempt to study further the relation between the ductus arteriosus, coarctation, and tubular hypoplasia of the aortic arch. Thirty-five aortic arch systems were studied using serial sectioning techniques. Twelve were from patients with coarctation and/or tubular hypoplasia. The other 23 hearts were from patients without aortic obstructive lesions, 7 from anatomically normal hearts, and the others from malformed hearts with anomalies elsewhere from the aortic arch. The anatomical study of the hearts with obstructive aortic lesions emphasised the necessity of distinguishing 'coarctation' from 'tubular hypoplasia', since the curtain lesion of coarctation was found to coexist with tubular hypoplasia in some cases. The histological study showed that the ductus was easily distinguished from the walls of the aorta or pulmonary artery. In all these cases with coarctation or tubular hypoplasia a sling of ductal tissue was located around the aortic isthmal orifice. In 6 hearts a diaphragm of ductal tissue was seen to form the coarctation lesion.
Adult↗
The cardiac conduction system in situs ambiguus.
The cardiac specialized conduction tissue was studied by serial sectioning in 13 cases of situs ambiguus. In four cases of right isomerism, we found paired sinus nodes in relation to a crista terminalis, and in each case a sling of conduction tissue between two atrioventricular nodes was present regardless of the ventricular morphology or cardiac position. In the cases with left isomerism, the sinus node was hypoplastic and abnormally located. We saw two types of atrioventricular conduction systems. In the three cases in which the morphologically right ventricle lay to the right of the morphologically left ventricle (presumed d-loop), a single atrioventricular bundle arose from a normally located atrioventricular node. In the five cases in which the morphologically right ventricle lay to the left of the morphologically left ventricle (presumed l-loop) and in the one case with a univentricular heart, paired atrioventricular nodes were present, linked or potentially linked by a sling of conduction tissue.
Atrioventricular Node↗
Anatomical closure of the ductus arteriosus: a study in 35 specimens.
The process of anatomical ductal obliteration appears to be gradual and to involve proliferation of intima and media (mainly the latter) producing mounds, mucoid-filled spaces and fragmentation of the internal elastic membrane. Dissociation of the inner media may also be involved. The persistent ductus can be recognized histologically, and its clinical significance is discussed.
Child, Preschool↗
Complete transposition of the great arteries with intact ventricular septum and left ventricular outflow tract obstruction. Surgical management and anatomic considerations.
Surgical management of patients with complete transposition and intact ventricular septum may become difficult in the presence of left ventricular outflow tract obstruction. A Mustard operation and direct resection of the obstruction through the pulmonary artery has been the treatment of choice for this combination. Our study of the structure of the left ventricular outflow tract in four specimens with the anatomic findings of complete transposition, intact ventricular septum, and subpulmonary stenosis suggests that direct resection of the stenosis through the pulmonary artery can seldom be adequate without major risk of damaging either the mitral valve or the conduction tissue. An alternative procedure, namely, a combined Mustard operation and insertion of an external conduit from the left ventricle to the main pulmonary artery, has been employed in the management of six patients with this combination of lesions. One early and one late death occurred. Postoperative cardiac catheterization performed in all of the survivors before discharge from the hospital showed good relief of the stenosis and no significant gradient across the conduit.
Angiocardiography↗
Histological study of the cardiac conducting system as a routine procedure.
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Child, Preschool↗
Heart block and sudden death associated with fibrosis of the conduction system at the margin of a ventricular septal defect.
Isolated ventricular septal defects in clinically well patients are not generally thought to cause sudden death. We document a case in which heart block, with sudden collapse and death, is related to the presence of fibrous interruption of the conduction system of the heart due to progressive fibrous closure of a small ventricular septal defect.
Fatal Outcome↗
The anatomy of a collection.
An old collection of 81 congenitally malformed hearts was examined in detail using the system of sequential segmental analysis. The specimens were almost entirely from infants and young children who had died during the two decades between 1954 and 1973. There had been surgical intervention in 26 cases, and most of these patients died during or shortly after the operation. The various anomalies are listed, and the pattern of prevalence is contrasted to that of present-day collections. Among the many interesting specimens there was a fine example of one of the rarest of cardiac anomalies, a criss-cross arrangement of atrioventricular connections. The collection, as an entity, gives an interesting historical insight of the state of congenital heart disease during the early years of the development of cardiac surgery.
Adolescent↗
A postmortem review of congenital cardiac malformations in a series of 180 adults, over the age of 16 years, born between 1865 and 1980.
The evolution of diagnosis and treatment of congenital heart malformations can be traced through patients surviving into adulthood. We reviewed the heart specimens from 180 patients aged 16 to 86 years and considered the morphological features, the nature of any interventional procedures, and the events leading to death. Based on the mode of clinical presentation, 33 cases were considered covert, and the remaining 147 cases were known or suspected to have a cardiac abnormality during life. Of the symptomatic cases, 60 had no surgical intervention, whereas 167 surgical procedures had been performed in the remaining 87 cases. Acquired heart disease was noted in 7 of the covert cases and in 16 of the symptomatic cases. Overall, there were only 3 instances of errors in clinical identification of significant morphological abnormalities, and 2 cases related to surgical procedures. This review emphasizes the value of autopsy examination for clinicopathologic correlations and the case for retention of cardiac specimens for teaching purposes.
Adolescent↗
A critical evaluation of results of partial left ventriculectomy.
BACKGROUND: Because of the variation in the surgical procedures designed to reduce ventricular radius, along with differences in hospital care, it is difficult to disentangle the factors that may contribute to the success or failure of the partial left ventriculectomy. METHODS AND RESULTS: We undertook partial left ventriculectomy in 18 patients, 10 suffering from idiopathic dilated cardiomyopathy and 8 from ischemic heart disease. We assessed the amount of reduction in wall stress, the systolic thickening of the ventricular wall, and the extent of connective tissue in the excised segment of the wall. Of the overall group, six patients died, three from infarction, one of stroke, one with asystole, and one with ventricular fibrillation. The mean decrease in measured mesh tension was 40% (p < 0.001). Most patients exhibited improvements postoperatively in terms of the systolic thickening of the posterior and superior free walls of the left ventricle. In those in whom the events could be monitored, life-threatening arrhythmias posed complications in three of four patients with ischemic heart disease, and in two of six patients suffering from idiopathic dilated cardiomyopathy. In one patient, death was associated with a transmural alignment of fibrous tissue. CONCLUSIONS: Our measured reductions in myocardial mesh tension were in keeping with the anticipated theoretical reduction in wall stress expected from partial ventriculectomy. The basic concept underscoring surgical maneuvers to reduce ventricular radius, therefore, is sound. A potential trap is the resection of the marginal artery. Critical myofibrosis was a rare complication. Arrhythmias, which are common, can successfully be treated by implantation of antitachycardic and defibrillatory devices.
Aged↗
The surgical anatomy of ventricular septal defect part IV: double outlet ventricle.
In this fourth part of our series of articles concerned with the surgical anatomy of ventricular septal defects (VSDs), we have analyzed the arrangements when both arterial trunks arise from the same ventricle. The essence of these anomalies is that the interventricular communication is an integral part of the circulation. Unless the surgeon constructs an alternative route of exit, closure of this defect would isolate one of the ventricles. The usual surgical approach, therefore, is to patch the hole between the ventricles into one or other of the subarterial outflow tracts. This means that all the components of the ventricular outflow tracts are of potential surgical importance. In hearts with double outlet right ventricle, the VSD can be categorized as being subaortic, subpulmonary, doubly committed, or non-committed. It is also important to determine whether its anatomical borders, as seen from the right ventricle, are in part fibrous or exclusively muscular, so as to establish the location of the atrioventricular conduction axis. It is possible, according to the nature of these borders, to place the defects into one of three groups, perimenbranous, muscular, or doubly committed and juxta-arterial. The size of the defect is another important surgical consideration. Double outlet left ventricle is a significantly more rare malformation, but the rules for determining the disposition of the conducting tissues are the same.
Double Outlet Right Ventricle↗
Hemodynamic effects of centrally administered adrenomedullin (13-52) in anesthetized rats.
This study was conducted to investigate the effect of intracerebroventricular administration of adrenomedullin (13-52) [ADM(13-52)], a novel hypotensive peptide, on the hemodynamic parameters of anesthetized rats. ADM(13-52) was administered centrally in a dose of 0.4-3.2 nmol/kg. It provoked marked, prolonged and dose-dependent increases in mean arterial blood pressure, heart rate, stroke volume, cardiac index, left ventricular pressure, left ventricular dp/dtmax and dp/dtmin, but reduction in total peripheral resistance index. In addition, intracerebroventricular administration of ADM(13-52; 1.6 nmol/kg) provoked a marked increase in renal sympathetic nerve activity. Intracerebroventricular administration of artificial cerebrospinal fluid had no effect on the hemodynamic parameters and renal sympathetic nerve activity. The results indicate that ADM(13-52) exerts a central action on the cardiovascular system. The mechanisms of hemodynamic changes induced by central ADM(13-52) were preliminarily analyzed in this study. ADM might play a role in the central control of the cardiovascular system, although the confirmed mechanisms and the physiological implications are undetermined.
Adrenomedullin↗
Isomerism of the atrial appendages in the fetus.
Thirty hearts from fetuses with visceral heterotaxy were examined to determine the range of cardiac malformations. By examining the morphology of the atrial appendages, 20 hearts were identified as having left isomerism (67%) and 10 hearts right isomerism (33%). Fifteen of the hearts with left isomerism had biventricular atrioventricular connections and five had univentricular atrioventricular connections. All 10 hearts with right isomerism had biventricular atrioventricular connections. Flow to the pulmonary arteries was obstructed or occluded in 6 hearts with left isomerism (30%) and 7 hearts with right isomerism (70%). Obstruction to aortic flow was present in 4 hearts with left isomerism (20%). Anomalies of the systemic and pulmonary veins were common in both groups. The suprarenal portion of the inferior caval vein was interrupted in 11 hearts with left isomerism (55%) and 1 heart with right isomerism (10%). Atrioventricular septal defect was present in 13 hearts with left isomerism (65%) and 9 hearts with right isomerism (90%). The arrangement of the liver or stomach in each group was not consistent, nor was the status of the spleen. The constellations of cardiac malformations in both groups corresponded to those known in postnatal life and similar guidelines for their identification were applicable.
Aorta, Thoracic↗
Morphological features of the levoatriocardinal (or pulmonary-to-systemic collateral) vein.
Three cases with an anomalous pulmonary-to-systemic collateral vein (levoatriocardinal vein) connecting the left atrium or one of the pulmonary veins to a systemic vein are described. In two of these cases the atrial septum is intact, the left atrioventricular connection is absent (mitral atresia), and the anomalous vein is the escape channel for pulmonary venous return. In the remaining case, a muscular membrane divides the left atrium, separating the pulmonary venous component from the distal component. The collateral vein may be mistaken for the vertical vein that is associated with totally anomalous pulmonary venous connections, but in all our cases the pulmonary veins inserted normally into the left atrium. Cross-sectional echocardiography, including conventional and color flow Doppler mapping, should overcome potential difficulties in diagnosis.
Coronary Circulation↗
Zinc profiles in rheumatoid arthritis.
Evidence has accumulated which suggests that zinc may play an important role in immune function and inflammation. In this study we examined the zinc status in patients with rheumatoid arthritis (RA), osteoarthritis, other rheumatic diseases and healthy controls. Results indicate that serum and plasma zinc levels are decreased significantly in patients with RA. Reduced zinc values may be due to decreased albumin-bound and micromolecular protein-bound zinc.
Adult↗
Study of the cardiac conduction tissues in the paediatric age group.
We have reviewed our experience with study of the conduction system of the heart and tried to condense our experience in the hope of aiding others to study this neglected part of the heart. The techniques involved are not complicated but do require patience and attention to detail. The key to success is the ability to cut serial sections, and to mount and study sub-serial sections. The techniques used are briefly described and then attention is given to the removal of blocks, the single most important step in the whole procedure. Advice is offered on the optimal method of studying the sinus node and the atrioventricular junctional area in the normal heart. Thereafter methods are described for studying the conduction systems in hearts with abnormal atrioventricular nodes, with ventricular septal defects and with ventricular pre-excitation. Similar attention is then paid to sudden infant death syndrome with regard to the conduction system, to congenitally complete heart block and finally to acquired disease in congenitally malformed hearts. Hope is expressed that more may become interested in the study of this fascinating system, or else refer suitable hearts to those who already are.
Adolescent↗