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Biomedical subjects

M Lev

Publications and source records attributed to M Lev.

At least 181 records · Page 10Linked to original sources
PubMed1976

The conduction system in double outlet right ventricle with subpulmonic ventricular septal defect and related hearts (the Taussig-Bing group).

The Taussig-Bind group of hearts is that group in which the aorta emerges completely from the right ventricle, unrelated to the position of the ventricular septal defect (VSD), while the pulmonary trunk emerges at varying degrees from the right ventricle related to the location of the VSD. Several types of surgical procedures involve the VSD in these hearts. The conduction systems in six of these hearts were therefore studied. The atrioventricular (A-V) bundle lies in the inferior (posterior) wall of the defect on the left side beneath the summit of the ventricular septum. In some cases, the bundle may be proximal to the defect, thus lying intramuscularly, and only the right and left bundle branches are related to the defect. The pattern od development of the atrioventricular (A-V) node, bundle and bundle branches is related primarily to the development of the endocardial cushions and posterior ventricular septum, and not to that of the absorption of the bulbus.

Aorta↗
PubMed1976

Sudden death caused by benign tumor of the atrioventricular node.

Histologic study of the conduction system of the heart of a 16-year-old girl who died suddenly demonstrated a benign mesothelioma of the AV node, with almost complete replacement of the structure by the tumor. Teh past history was unremarkable, except for few syncopal episodes at 9 and 11 years of age and during pregnancy. Immediately postpartum, she developed a 2:1 AV block and intermittent complete AV block. Six weeks later, during diagnostic work-up in the cardiac catheterization laboratory, she died suddenly. Electrophysiological studies during this work-up disclosed complete AV dissociation, with normal QRS complexes. The block was proximal to the His-bundle recording site, with a normal H-V interval. Occasional syncopal attacks in young adults should alert the physician to the possibility of this diagnosis and lead to pacemaker insertion.

Adolescent↗
PubMed1976

The conduction system in simple, regular (D-), complete transposition with ventricular septal defect.

This is a serial section study of the conduction system in 5 cases of complete (d-) transposition with ventricular septal defect (VSD) . In 3 of the cases with infracristal or intracristal VSD, the bundle lay in the posterior (inferior) wall on the left side of the defect. In the fourth case with infracristal VSD it was on the right side of this wall. In the case with a more distally situated VSD, the bundle branches skirted the anterior and distal walls of the defect. This study shows that in closure of the VSD in complete transposition, the posterior wall of the defect in some cases, and in others the anterior and distal walls of the defect are to be handled judiciously. The right side of this wall is probably safer to handle from the standpoint of block than the left side in most cases. His bundle recording during open-heart surgery may be indicated in large or unusually located VSD's to delineate the course of the conduction system and thereby to avoid atrioventricular (A-V) block.

Child, Preschool↗
PubMed1976

Anatomic variations in underdeveloped right ventricle related to tricuspid atresia and stenosis.

In the anatomy of 416 hearts, the seat of tricuspid stenosis or atresia is examined, with special reference to Fontan-like surgical procedures. A classification is offered which includes cases with and without regular or inverted transposition, and with decreased or increased pulmonary flow. The size and thickness of the right atrium, the size and architecture of the right ventricle, the size of the pulmonary tree, the types of atrial and ventricular septal defects, the condition of the mitral valve, and the size and thickness of the left atrium and left ventricle are analyzed. In addition the various intracardiac and extracardiac abnormalities are enumerated. Reference is also made to the tendency of the aorta and pulmonary trunk to override the septum, in some cases producing double-outlet left ventricle. It is considered that many cases of tricuspid valve atresia and stenosis with or without transposition may be amenable to Fontan-like procedures in the proper age group. All the above anatomic considerations have a bearing on the suitability and type of operative tricuspid bypass procedures, and they may influence the prognosis of surgical therapy.

Abnormalities, Multiple↗
PubMed1975

Conduction system in systemic lupus erythematosus with atrioventricular block.

We describe the clinical course and the postmortem cardiac findings in a 12 year old girl with systemic lupus erythematosus, complete heart block, renal failure and hyperkalemia. The conduction system was examined by serial section. The sinoatrial and atrioventricular nodes were found to be almost completely replaced by granulation tissue; we believe that this finding is related to the systemic lupus. The hyperkalemia is not considered to be the cause of the block, since the block persisted despite the lowering of the blood potassium level and the morphologic findings in this case are not found in hyperkalemia.

Atrioventricular Node↗
PubMed1975

Mahaim and James fibers as a basis for a unique variety of ventricular preexcitation.

This report concerns pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast. Electrocardiograms revealed predominantly normal sinus rhythm with a normal P-R interval and narrow QRS complex. Episodes of sinus rhythm, short P-R interval and QRS widening (with delta wave) were also recorded. During preexcitation QS complexes were noted in leads II, III, aVF, V1 and V4 to V6. Delta waves were negative in leads II, III, aVF and V1 isoelectric in leads V4 to V6 and positive only in leads I, aVL, V2 and V3. This case thus defies classification into any known variety of preexcitation. Complete serial sections, cut through the entire conduction system and both atrioventricular (A-V) rims, totaled 18,600 sections. These revealed no bundle of Kent. Instead, Mahaim fibers histologically identified as His bundle tissue gave off from the A-V bundle to both the right and the left sides of the septum associated with the normal fibers of James. This case reveals that (1) fibers of James can bypass the A-V node, (2) fibers of Mahaim can conduct, and (3) there are types of preexcitation in addition to types A and B.

Atrioventricular Node↗
PubMed1975

Sensitivity of a Bacteroides melaninogenicus strain to monosaccharides: effect on enzyme induction.

The inhibition of growth in Bacteroides melaninogenicus by sugars in described. Monosaccharides such as D-glucose, D-galactose, D-mannose, and D-fructose are inhibitory at low concentrations, whereas the disaccharides sucrose and lactose are not inhibitory even at high concentrations. The major inhibitory effect of the sugar is found during the transition of lag to logarithmic growth phases. There was no primary effect of D-glucose on protein, ribonucleic acid, or deoxyribonucleic acid synthesis on cells in transition from lag to logarithmic growth. However, the addition of glucose or galactose completely abolished the induction of 3-ketodihydrosphingosine synthetase by vitamin K in vitamin K-depleted cells. Futhermore, in cells which were not vitamin K depleted, the level of this enzyme was drastically reduced by the addition of the sugar. Cyclic adenosine 5-monophosphate was unable to reverse the growth inhibition produced by glucose. In actively growing cultures, addition of sugar slows the growth rate. In these experiments the level of 3-ketodihydrosphingosine synthetase fell only after the cells had assumed the slower rate of growth. There were two indications that D-galactose was more inhibitory than D-glucose; in the presence of 0.1% D-galactose cells in lag phase did not show the increase in turbidity found in similar cells placed in medium with 0.1% D-glucose, and also D-galactose caused a greater decrease in the growth rate of actively growing cultures than was found with D-glucose. These studies suggest that the inhibitory effect of monosaccharides in lag leads to logarithmic growth transition can be ascribed to an effect on enzyme induction. On the other hand, the ability of many monosaccharides to inhibit growth, and the greater inhibitory property of D-galactose compared with D-glucose, suggests that other mechanisms may be operative as well.

Bacterial Proteins↗
PubMed1975

Hemodynamic consequences of delayed ventriculoconal conduction in the frog Rana catesbeiana.

We investigated the function of the conus arteriosus in the bullfrog Rana catesbeiana using a combination of anatomical and physiological techniques. Although there is a normal delay in ventriculoconal conduction and we could induce a spectrum of ventriculoconal conduction disturbances by manipulating the region of the ventriculoconal junction, we found no histological evidence of specialized conducting myocardial tissue in this region. The performance of the conus arteriosus was explored during various disturbances of ventriculoconal conduction and also during hemodynamic disturbances produced by hemorrhage and afterloading. The conus was found to contribute little to forward flow under ordinary circumstances, but its contribution increased greatly during bleeding or partial occlusion of the truncus. In contrast to the conclusion of others, no evidence could be adduced to support the idea that the conus serves as a depulsating chamber. Disparities in previous reports concerning the operation of the conus as a booster pump are attributed to special experimental circumstances.

Animals↗
PubMed1975

Return of normal conduction after paroxysmal heart block. Report of a case with major discordance of electrophysiological and pathological findings.

This report describes a 52-year-old male with paroxysmal heart block as well as left and right bundle branch block, resulting in Stokes-Adams attacks. The patient experienced a return to 1:1 atrioventricular (A-V) conduction with narrow QRS within 48 hours of the attacks and heart block never recurred. Electrophysiological studies three weeks later revealed a narrow QRS, a normal H-V interval (36 msec), 1:1 A-V conduction up to an atrial paced rate of 210 beats/min, and normal refractory periods with atrial extrastimulus techniques (His-Purkinje system refractory periods less than 370 msec). The patient died from a cerebral embolus incurred during diagnostic left heart catheterization two days after electrophysiological studies. Postmortem examination revealed calcific aortic stenosis with calcific impingement upon the pars membranacea resulting in compression of the distal His bundle and marked disruption of the proximal portions of both bundle branches. This report documents a major limitation of electrophysiological studies, this limitation being that these studies may be totally normal on one occasion in a patient with pathologically significant chronic conduction disease, which may become clinically manifest on another occasion.

Adams-Stokes Syndrome↗
PubMed1975

The course of the conduction system in single ventricle with inverted (L-) loop and inverted (L-) transposition.

The conduction systems of three hearts with single ventricle and inverted (L-) loop and inverted (L-) transposition were studied by serial section. The course of the conduction system was similar in all three hearts. The regular (posterior) atrioventricular (A-V) node was rudimentary and did not form the bundle of His. An accessory (anterior) A-V node was present in the roof of the right atrium. This node pierced the connective tissue adjacent to the right side of the pulmonary annulus to form the bundle of His. The bundle proceeded into the main ventricular chamber lying on the septum between this chamber and the small outlet chamber. It bifurcated a varying distance from the defect in this septum. The right bundle branch proceeded through the septal wall to the trabeculae of the outlet chamber. The left bundle branch proceeded to caudad on the anterior wall of the main ventricular chamber. An unusual feature in one case was the splitting of the anterior node into two parts, one forming the bundle of His, and the other giving off Mahaim fibers to the ventricular myocardium. The surgical importance of avoiding the right side of the pulmonary annulus and the region adjoining the defect is stressed.

Atrioventricular Node↗
PubMed1975

Electrophysiologic and pathologic correlations in two cases of chronic second degree atrioventricular block with left bundle branch block.

This study concerns two cases of chronic 2 degrees atrioventricular (A-V) block with left bundle branch block (LBBB). Pathological studies included serial section of the conduction systems. Case 1 had type I 2 degrees block with LBBB. Electrophysiological studies revealed type I 2 degrees block proximal to the His bundle recording site and a prolonged H-V interval (60 msec). Pathologically there was a moderate to marked fibrosis of the approaches to the A-V node and of the A-V node, marked fibrosis of the left bundle branch, and moderate involvement of the right bundle branch. The changes proximal to the His bundle were more marked than the changes distal to this bundle. Case 2 had type II and 2:1 2 degrees A-V block with LBBB. Electrophysiologically the site of block was distal to the His bundle recording site, and there was a prolonged A-V node and severe involvement of both bundle branches. The changes distal to the His bundle were more severe than the changes proximal to the His bundle. This study reveals that the electrophysiologic data more closely approximated the pathologic findings than did surface electrocardiographic data alone. It also emphasizes that there may be multiple sites of disease in chronic 2 degrees block with bundle branch block.

Aged↗
PubMed1975

Infarct of the myocardium with aneurysm in a 13-year-old girl.

We present the case of a girl with an infarct and an aneurysm of the left ventricle after viral disease at the age of six years. She died suddenly at 13 years of age. Autopsy findings revealed occlusion of the anterior descending and narrowing of the right coronary artery. The possible relationship of virus disease to the vascular disease is discussed.

Angiocardiography↗
PubMed1975

The surgical anatomy of pulmonary atresia with ventricular septal defect: pseudotruncus.

This is a study of 172 heart specimens with pulmonary atresia and ventricular septal defect (VSD)--pseudotruncus. These are divided into simple and complicated types. In the simple type the following may be of importance from the surgical standpoint: (1) the size of the pulmonary arteries, (2) the origin of the aorta, (3) the amount of pulmonary flow, (4) the size of the left side of the heart, (5) the presence of bronchial and/or abnormal systemic supply to the lungs, (6) the coronary circulation, and (7) the presence of intra- and extracardiac associated abnormalities. The following factors may be important in the complicated types: (1) Complete transposition may accompany the complex; (2) instead of the VSD there may be a common atrioventricular (AV) orifice; (3) the pulmonary atresia with VSD may be associated with tricuspid or mitral atresia or with common or single ventricle; (4) the entity may be associated with abnormal position of the entire heart or some of its component chambers.

Abnormalities, Multiple↗