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Biomedical subjects

M Lev

Publications and source records attributed to M Lev.

At least 91 records · Page 5Linked to original sources
PubMed1986

Conduction system in cases of sudden death in congenital heart disease many years after surgical correction.

The conduction system and the entire heart were examined histologically in four patients with congenital heart disease who had surgery many years before they died suddenly. All were asymptomatic, in sinus rhythm and living normally. The sudden death may have been related to alterations in the conduction system, previously present, or introduced by the previous surgery, or related to inflammatory phenomena, an outgrowth of the previous surgery.

Adult↗
PubMed1986

The surgical anatomy of the heart in tubular hypoplasia of the transverse aorta (preductal coarctation).

Two hundred nineteen hearts with preductal coarctation (tubular hypoplasia) were analyzed in the laboratory to aid in surgical correction. One hundred fourteen were without and 105 were with ventricular septal defect. We believe the following anatomic findings may be responsible for the mortality and morbidity in surgical repair. The smallness and thinness of the left atrium (40% in those hearts without and 24% in those with ventricular septal defect); the smallness and thinness of the left ventricle (46% in those without and 32% in those with ventricular septal defect); the presence of mitral stenosis (35% in those without and 24% in those with ventricular septal defect); the presence of unicuspid or bicuspid dysplastic aortic valve (49% in those without and 50% in those with ventricular septal defect); the presence of a combination of aortic and mitral stenosis (22% in those without and 9% in those with ventricular septal defect); the location of the ventricular septal defect when present; and the possibility of stenosis or insufficiency of the dysplastic aortic valve in the late postoperative period.

Aortic Coarctation↗
PubMed1985

Electrophysiologic and anatomic changes in the atrioventricular junction of dogs after direct-current shocks through tissue fixation catheters.

Barb-tipped fixation electrode catheters were inserted under fluoroscopic control in the region of the atrioventricular (AV) node in 6 dogs. A series of direct-current shocks (20 to 240 J) were delivered from the electrode catheter to a back plate. Serial electrophysiologic studies were performed before and 2 to 3 weeks after delivery of the shocks. In general, low-energy shocks--20 to 180 J--resulted in predominant damage to the approaches to the AV node, the AV node and common bundle, whereas larger shocks created diffuse damage involving the His bundle and bundle branches. Despite histologic damage to the AV junction, only minimal changes in AV conduction were observed. Thus, there is a large safety margin for AV conduction.

Animals↗
PubMed1985

Study of the conduction system in a population of patients with sudden infant death syndrome.

The conduction system of 23 infant hearts, 15 of sudden infant death syndrome (SIDS) and eight of those dying from known cause, was serially sectioned. A left-sided His bundle was found more commonly in (SIDS) (eight of 15) than in the controls (two of eight). Taking into account a previous study in which a left-sided His bundle was found in only four of 32 hearts from all age groups, this is statistically significant and may be a factor promoting SIDS.

Atrioventricular Node↗
PubMed1985

Truncus arteriosus with interrupted aortic arch: report of a successful surgical repair.

The association of truncus arteriosus with interrupted aortic arch represents a formidable surgical challenge. Two successful repairs have been reported, but none for the past ten years. This report presents a third successful repair using a technique that allows the widely patent ductus arteriosus to maintain continuity between the truncus (with pulmonary arteries detached) and the descending aorta. Right ventricle-pulmonary artery continuity is established in the usual way with a porcine-valved conduit. While long-term potential difficulties with this approach are recognized, it appears to give satisfactory initial palliation and to be an acceptable method of treatment for this combination of defects. The embryology and the anatomy of the lesion are briefly discussed.

Aorta, Thoracic↗
PubMed1985

Functional aortic valve atresia in transposition of the great arteries.

The criterion for the diagnosis of functional atresia of a patient semilunar valve is met when the pressure in a ventricle remains lower than that in the related great artery throughout systole so that no forward flow can occur. Functional pulmonary valve atresia has been well recognized in infants with normally related great arteries and massive tricuspid valve incompetence. The cardiac physiology and anatomy of an infant with transposed great arteries and functional aortic valve atresia is reported for the first time. The peak systolic pressure in the right ventricle was 30 mm Hg and in the aorta 64 mm Hg. The causes for right ventricular incompetence were abnormalities of the tricuspid valve and hypoplasia of the ventricular free wall. Three other cases with similar ventricular anatomy and physiology but with anatomic atresia of the aortic valve are reviewed. The possibility that under these physiologic circumstances during fetal life functional atresia develops first, and that anatomic fusion of idle semilunar cusps develops as a secondary phenomenon, is discussed.

Aortic Valve↗
PubMed1985

Isolated prolapse of the tricuspid valve.

Tricuspid valve prolapse has remained a poorly defined entity. Some authors have stated that prolapse isolated to the tricuspid valve has not been documented. This report contains three cases of isolated tricuspid valve prolapse including the first pathologically confirmed case. A review of worldwide literature including all reported cases of isolated tricuspid valve prolapse is also presented. Although signs and symptoms are similar to those found with mitral valve prolapse, tricuspid valve prolapse may occasionally be differentiated by auscultation. The diagnostic criteria of tricuspid valve prolapse are thoroughly discussed for each of the presently available invasive and noninvasive techniques. Right heart catheterization can define such prolapse but is invasive and requires meticulous technique. Two-dimensional echocardiography supersedes M-mode because of the superior spatial evaluation of the tricuspid leaflets in relation to the right atrium and ventricle. Multiple views including a long-axis view of the right ventricular inflow are often required. This parasternal echocardiographic window is often the only one which permits adequate visualization of the posterior leaflet. The pathologic findings of tricuspid valve prolapse are similar to those of mitral valve prolapse. This report concludes with a description of associated conditions. Severe tricuspid regurgitation has not been noted with tricuspid valve prolapse in the absence of superimposed disease, yet much remains undefined concerning the clinical significance of this condition.

Aged↗
PubMed1985

The conduction system in patients with a prolonged QT interval.

The conduction system and the myocardium of five patients with Romano-Ward syndrome and one patient with the Jervell and Lange-Nielsen syndrome were studied to determine the cause of the prolonged QT interval. The patients were 9 and 15 months and 2, 5 and 19 years of age, respectively. All had a prolonged QTc interval. A sixth patient was a 16 year old girl who died suddenly; several members of her family had a prolonged QT interval. The only common finding in the conduction system in all cases was marked fatty infiltration in the approaches to the atrioventricular (AV) node. In four, the AV bundle was lobulated, with loop formation in one. In four, the AV bundle and bundle branches showed fibrosis. The ventricular myocardium in all cases was chronically inflamed. In two cases, the AV node was partially embedded in the central fibrous body. It is not clear how these changes are related to the disturbance in the repolarization process and the prolongation of the QT interval. However, it is interesting that all patients had an abnormality in the conduction system.

Adolescent↗
PubMed1985

Sudden death after catheter-induced atrioventricular junctional ablation.

Atrioventricular (AV) junctional ablation was performed in a 59-year-old woman with recurrent atrial fibrillation refractory to treatment with digoxin, beta-blockers, verapamil, quinidine, procainamide, and amiodarone. She received two shocks of 500 J which produced complete AV block. After six weeks, both 24-hour ECG recordings and an exercise tolerance test showed infrequent premature ventricular complexes, 3 degrees AV block, and paced ventricular rhythm with 100 percent capture. She suddenly collapsed and was found to be in ventricular fibrillation and could not be resuscitated. Serial sections of the conduction system showed marked fatty infiltration of the approaches to the AV node with almost complete separation from the node. A partially fibrosed atrioHisian connection was also present. Fibroelastosis with chronic inflammatory changes was present in the AV node, bundle of His, and right and left bundle branches. In addition, marked inflammatory changes with fibrosis were present in the atrial septum, in the summit of the ventricular septum, with degenerative changes in the tricuspid and aortic valves. The sequelae of these findings outside the conduction system in other patients remains to be determined.

Atrial Fibrillation↗
PubMed1985

Inhibition of cerebroside synthesis in the brains of mice treated with L-cycloserine.

Subcutaneous injection of L-cycloserine resulted in a 28% reduction in cerebroside levels in mouse brain but had no effect on the levels of gangliosides. In contrast, intraperitoneal injection results in a reduction of ganglioside as well as cerebroside + sulfatide levels. The route of injection influenced the degree of 3-ketodihydrosphingosine synthase inhibition. Intraperitoneal injection caused a rapid decrease in synthase activity followed by recovery over 48 hr, whereas subcutaneous injection resulted in no inhibition over this time; only after daily injection for a week was synthase activity reduced 35%. One week following cessation of L-cycloserine administration, enzyme activity had recovered, whereas the cerebroside level continued to fall. All lipids and enzymes showed normal levels 3 weeks post-cycloserine administration. L-[3H]serine incorporation into glycolipids showed that cerebroside synthesis was most affected, whereas sulfatide synthesis was less affected. One week after cessation of cycloserine treatment, cerebroside synthesis was still severely inhibited, whereas sulfatide levels were near normal. Two weeks after cessation of L-cycloserine administration, synthesis of these glycolipids was similar to that of controls.

Animals↗
PubMed1984

Microtransection of the His bundle with laser radiation through a pervenous catheter: correlation of histologic and electrophysiologic data.

This study describes microtransection of the His bundle with a pervenous laser catheter in a live dog. In an adult mongrel dog anesthetized with Nembutol , administered intravenously, electrode catheters (No. 5Fr and 6Fr ) were inserted through a femoral vein and positioned in the high right atrium for atrial pacing and in the His bundle region for recording of His bundle electrograms. The AH and HV intervals were measured during normal sinus rhythm and atrial pacing. Through another femoral vein, a laser fiber was inserted through a lumen catheter (No. 7Fr ) with a preformed curved tip. Under fluoroscopic control, the laser fiber tip was positioned immediately next to the His bundle electrode catheter. During continuous His bundle recordings and fluoroscopic monitoring, short bursts (10 to 60 seconds) of argon laser were delivered (2.5 W) in order to produce His bundle interruption and complete heart block. Escape of a His bundle rhythm (cycle length = 1,100 ms) with QRS morphologic characteristics and duration similar to that of normal sinus rhythm was noted. "Split" His bundle potentials were recorded with an unchanged AH (50 ms) and an H'V interval of 20 ms. After the dog was killed, serial sections of the conduction system of the heart were analyzed. Histologic findings showed excellent correlation with electrophysiologic observations and validated "split" His bundle potentials. The laser radiation produced microtransection of the His bundle with a channel of tissue dissolution 0.2 to 0.3 mm wide in diameter. The latter passed through the His bundle at the junction of penetrating and branching segments, dividing it into superior and inferior portions that retained continuity with proximal and distal His bundle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

L-cycloserine inhibition of sphingolipid synthesis in the anaerobic bacterium Bacteroides levii.

L-cycloserine was found to significantly inhibit the activity of the first enzyme of the sphingolipid pathway when added to growing cultures of Bacteroides levii. The effect of cycloserine on the synthesis of the sphingolipids showed that ceramidephosphorylethanolamine was inhibited to a greater degree than ceramidephosphorylglycerol, although synthesis of both was significantly inhibited by cycloserine as determined by [32P] incorporation and phosphorus determination. In contrast, synthesis of phosphatidylethanolamine and phosphatidylglycerol was not inhibited by L-cycloserine at 100 micrograms/ml. Peturbation of sphingolipid synthesis by L-cycloserine may therefore provide a useful tool for the study of the function of these membrane lipids.

Anaerobiosis↗
PubMed1984

Origin of both coronary arteries from the pulmonary trunk associated with hypoplasia of the aortic tract complex: a new entity.

The first case of origin of both coronary arteries from the pulmonary trunk, associated with hypoplasia of the aortic tract complex is reported. Although this is a lethal anomaly, as both coronary arteries originate from the pulmonary artery, it is conceivable that surgical intervention could make this unusual entity a viable one. Possible surgical techniques are discussed.

Aortic Valve↗
PubMed1984

Origin of the left coronary artery from the right pulmonary artery.

Origin of the left coronary artery from the right pulmonary artery has rarely been documented. This is the first such case in a heart with an intact ventricular septum and paraductal coarctation of the aorta. Although an antemortem diagnosis was made and the anomalous left coronary artery was ligated, the patient, a 3 1/2 month old infant, died 1 day after surgery. Autopsy confirmed the diagnosis, but revealed that the left coronary artery was dominant. It is believed that the fatal outcome in the infant was, in part, due to the dominance of the left coronary artery and the effects of the coarctation on the already ischemic left ventricle.

Aortic Coarctation↗
PubMed1984

Inhibition of sphingolipid synthesis by cycloserine in vitro and in vivo.

D- and L-cycloserine were shown to be irreversible inhibitors of the first enzyme of the sphingolipid pathway, 3-ketodihydrosphingosine synthetase, in a study using bacterial and brain microsomal enzymes. L-Cycloserine was shown to be 100 times more inhibitory than the D-isomer for the brain microsomal enzyme in vitro. In vivo, L-cycloserine caused a 70% inhibition of brain microsomal enzyme. Following one injection, enzyme activity recovered 80% of normal after 16 hours. Daily dosages of L-cycloserine on a regimen of intraperitoneal injection for 7 days caused a significant reduction in total brain ganglioside and cerebroside plus sulfatide levels.

Animals↗
PubMed1984

Comparative inhibition of bacterial and microsomal 3-ketodihydrosphingosine synthetases by L-cycloserine and other inhibitors.

Eleven compounds were examined for their capacity to inhibit the first enzyme of the sphingolipid pathway, 3-ketodihydrosphingosine synthetase. Of these, L-cycloserine was the most potent, affecting both bacterial and brain microsomal enzymes to a significant degree at 0.04 mM. D- and L-cycloserine irreversibly inactivated the enzyme, indicating a suicide substrate mode of action. L-Cycloserine was a more potent inhibitor of the growth of Bacteroides levii than was D-cycloserine, indicating that inhibition of sphingolipid synthesis could be a factor in the growth inhibition.

Animals↗
PubMed1984

Dystrophica myotonia. Correlative electrocardiographic, electrophysiologic, and conduction system study.

Correlative ECG, electrophysiologic (EPS), and pathologic findings of the conduction system (CS) in dystrophica myotonia has not been documented to our knowledge in the English literature. We present such a correlation in two cases. The first at age 55 had right bundle branch block, left anterior fascicular block, and first-degree AV block. At age 65, ECG demonstrated type 1 AV block, and EPS revealed block proximal to the His bundle. Two years later, he died of pneumonia. The CS showed marked degenerative changes and fatty infiltration in the atrial septum and the approaches to the AV node, with marked fibrosis of the right bundle branch and partial interruption of the left bundle branch. Case 2 at age 32 had complete left bundle branch block. At age 35, she had syncope, and the ECG revealed type 2, 2:1, and complete AV block, as well as nonsustained polymorphic ventricular tachycardia; EPS showed block distal to the His bundle. A year later, she died in ventricular fibrillation. The CS revealed fatty infiltration in the approaches to the AV node, fibrosis completely interrupting the left bundle branch, and marked fibrosis of the right bundle branch. In both cases, there was fibrosis of the summit of the ventricular septum with irregularity in the size of the cells, vascular changes, and fatty infiltration of the atrial septum. There was good but not perfect correlation among ECG, EPS, and CS findings. The discrepancy was in the approaches to the AV node in case 2. It appears that dystrophica myotonia is a striated muscle disease and possibly a pan-muscle disease.

Adult↗