PubMed Health⌕ Search

Biomedical subjects

S C Klausner

Publications and source records attributed to S C Klausner.

18 recordsLinked to original sources
PubMed1988

Quantitative digital subtraction coronary angiography using videodensitometry. An in vivo analysis.

A videodensitometric method for measuring absolute cross-sectional area and diameter has been tested in living dogs with coronary artery stenoses created surgically by placement of small Silastic cuffs. Coronary arteriograms were performed using a circular tomographic unit to provide multiple views of each lesion, and measurements were made from logarithmically subtracted digital images. Dimensions of 13 stenoses of cross section 1 to 5 mm2 and adjacent reference segments (2 to 9 mm2) were determined by histologic sectioning of the segments after injection with a rapidly hardening plastic fixative under physiologic pressure. Two different methods were tested for calculating cross-sectional area. On 238 measurements, 102 of normal vessel segments and 135 of stenoses, both methods showed good correlation with histologic measurements, with slopes of 0.929 + (SD) 0.037 (r = 0.8563) and 0.948 + (SD) 0.037 (r = 0.8554). Multiple measurements of each segment produced values within 30% of the true absolute cross sectional area in most cases. The method shows promise as a means for quantitating absolute dimensions of vessels in clinical arteriography.

Absorptiometry, Photon↗
PubMed1985

The aging heart.

Pathologic studies of the myocardium and valvular structures have failed to provide convincing evidence of gross or microscopic changes that can be ascribed to aging alone. Lipofuscin accumulation and basophilic degeneration in cardiac muscle cells appear to be the most consistent findings associated with aging, but they are found in other conditions. Without doubt, pathologic changes in the myocardium, valves, and coronary arteries are found more frequently in the hearts of elderly persons, but those changes are caused by disease processes associated with an aging population rather than the aging process itself. Both the sinus and atrioventricular nodes decrease in size with age owing to a loss of cellularity. These structures become infiltrated with collagen, elastic tissue, and reticular fibers. Some have found infiltration also with fat. Amyloid deposition, basophilic degeneration of cells, and lipofuscin accumulation occur but probably do not cause functional abnormalities. Similar but less dramatic changes occur in the bundle of His and individual bundle branches. Most of the data suggests that these aging changes are not due to vascular insufficiency. Age-related changes in intrinsic mechanical function have been identified as a prolongation of contraction duration, decreased inotropic responses to catecholamines and cardiac glycosides, and an increase in mechanical refractoriness. Other possible age-related changes include alterations in relaxation, which may or may not be independent of the prolongation of contraction, and changes in the viscoelastic properties of cardiac muscle. When examined in the context of the components of a model of excitation-contraction coupling, changes in action potential duration and the function of the sarcoplasmic reticulum emerge as the most likely bases for the changes. The electrical characteristics of sinus, atrioventricular, and His-Purkinje cells as well as atrial and ventricular muscle cells change with age. The sinus rate decreases, as do the escape rates of other automatic cells. The sensitivity and electrical changes produced by cardiac drugs also is affected by aging. Transmembrane electrical aging changes have been attributed to changes in the slow inward current caused by calcium and alterations in potassium conductance as well as other ionic currents. An age-related change in the function of the sarcoplasmic reticulum may be contributory. There appear to be age-related changes in both the anatomy and physiology of major arteries.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1984

Alcohol and the heart.

Acute alcohol ingestion can lead to alterations of either mechanical function or electrophysiologic properties of the heart, whereas chronic consumption can lead to progressive cardiac dysfunction and congestive cardiomyopathy. On the other hand, alcohol appears to have a protective effect for coronary artery disease when consumed in low amounts, although prophylactic use of alcohol is not recommended.

Adult↗
PubMed1984

Extraction of an intravascularized pacemaker lead--a new approach to an unusual problem.

A new catheter approach to removing an intravascularized, nonfunctional pacemaker lead which was fixed at both distal (right ventricular endocardium) and proximal (brachiocephalic vein/superior vena cava) ends is described. This case also emphasizes the need for removal of an old pacemaker lead that caused bacteremia in a patient with a prosthetic aortic valve even when infection was presumed to be cured.

Aged↗
PubMed1984

Cerebellar ataxia due to procainamide toxicity.

It has become appreciated that drug levels of procainamide hydrochloride needed to suppress inducible ventricular tachycardia by programmed ventricular stimulation exceed the previously published therapeutic range. Cerebellar ataxia developed acutely in a patient receiving high-dose procainamide. This was associated with a marked increase in the serum drug level. Resolution occurred within three days after drug therapy was discontinued.

Administration, Oral↗
PubMed1983

A randomized trial of intracoronary streptokinase in the treatment of acute myocardial infarction.

Fifty patients with acute myocardial infarction were randomly assigned to receive either intracoronary streptokinase or standard (control) therapy within about three hours after the onset of pain. Coronary perfusion was reestablished in 19 of 24 patients receiving streptokinase. Streptokinase alleviated pain (as indicated by differences in subsequent morphine use). The Killip class was significantly improved after therapy with streptokinase, as were changes in radionuclide ejection fraction between Days 1 and 10 in surviving patients (+3.9 vs. -3.0 per cent, P less than 0.01). The echocardiographic wall-motion index also showed greater improvement after streptokinase treatment (P less than 0.01). Streptokinase therapy was associated with rapid evolution of electrocardiographic changes, which were essentially complete within three hours after therapy, but loss of R waves, ST elevation, and development of Q waves in the convalescent period were greater in the control group (P less than 0.01). The time required to reach peak plasma enzyme concentrations was significantly shorter after streptokinase. The incidence of early and late ventricular arrhythmias was not affected by treatment. We conclude that intracoronary streptokinase appears to have a beneficial effect on the early course of acute myocardial infarction.

Adult↗
PubMed1982

Quantitative analysis of segmental wall motion throughout systole and diastole in the normal human left ventricle.

We traced left ventricular contours, frame-by-frame throughout systole and diastole, of normal sinus beats from 30 degrees right anterior oblique ventriculograms from 32 normal patients. We separated both systole and diastole into 19 equal time intervals each and calculated regional lengths (R), normalized by both end-diastole length and relative time interval (T) in systole and diastole and diastole, for the middle inferior wall, distal inferior wall, apex, distal anterior wall, middle anterior wall, and proximal anterior wall. We also computed the relative velocities of R, delta R/ delta T, over each quarter of systole and diastole. Comparing systole with diastole, we found significant differences between paired values of R at all regions except the distal inferior wall, but these differences were not the same between regions. Between regions, mean R and delta R/ delta T values were significantly different as early as the first quarter of systole. Within a region, there were significant differences between mean R and delta R/ delta T values over intervals as short as one-fourth of systole or diastole. Thus, there is no homogeneity between regions in normal wall motion in both systole and diastole. This normal lack of homogeneity has important clinical implications for identifying abnormal wall motion in individual patients from ventriculographic measurements, and for using the information present in the diastole portion of the ventriculogram to characterize normal segmental function.

Age Factors↗
PubMed1982

Should a fixed external reference system be used to analyze left ventricular wall motion?

To investigate whether a fixed external reference system should be used to most accurately describe regional left ventricular wall motion, we used vectors to analyze a simple model of ventricular contraction. If measured in a fixed external reference system, motion of implanted radiopaque midwall markers may contain translational as well as contractile components. Therefore, comparisons of different reference systems that use marker motion measured in a fixed reference system as a standard will be biased unless proper corrections are included. We conclude that evidence to data does not indicate that the use of a fixed reference system is superior to other methods for analyzing regional ventricular wall motion.

Heart↗
PubMed1981

Changes in left ventricular wall motion after coronary artery bypass surgery: signal or noise?

We evaluated changes in ventricular wall motion after surgery by comparing smoothed, filtered measurements of regional percent shortening (RPS) from right anterior oblique ventriculograms in 37 patients before and after surgery. After surgery there was a significant (p less than 0.05) decrease in the number of regions with hypokinetic wall motion. The distribution of RPS values was also different (p less than 0.005). However, the mean value of RPS for the surgery group as a whole was not significantly altered. These data were contrasted with RPS data from 11 control patients, who were each studied twice but did not have surgical intervention. Similar analysis of the control group did not show any significant change between studies in the number of hypokinetic regions, and the distributions of RPS for the first and second angiograms were not different. We found a 10.3% absolute mean change in repeated measurements of RPS in the control group. We conclude that significant changes occurred after surgery that were not evident in the control group, and the amount of variability in repeated measurements of RPS suggests that analysis should be applied to group rather than individual data.

Coronary Artery Bypass↗
PubMed1980

Evaluation of left ventricular performance by gated radionuclide angiography.

Gated radionuclide angiography (RVG) in orthogonal projections was used to evaluate left ventricular volume, ejection fraction, and segmental wall motion. Images of the left ventricle at end-diastole and end-systole were outlined in two projections using a simple manual method. The perimeter drawings were digitized on a desktop computer, interfaced to an XY recorder and left ventricular volumes and ejection fraction calculated. The results were compared to contrast left ventriculography (CVG) in the same projections. RVG and CVG gave similar results for end-diastolic volume (r = .87, P less than 0.001), end-systolic volume (r = .95, P less than 0.001), and ejection fraction (r = .89, P less than 0.001) over a wide range of values. In 92% of all left ventricular segments analyzed, RVG and CVG showed only minor differences in the analysis of wall motion. Reproducibility of the method by a trained observer was excellent. Interobserver trials demonstrated that less well-trained observers consistently over- or underestimated volumes, emphasizing the need for prior experience in RVG analysis. Use of this manual method for analysis of gated equilibrium RVG in orthogonal projections appears to be a reasonably accurate, reproducible method for evaluating left ventricular function.

Angiocardiography↗
PubMed1979

The characteristic sequence for the onset of contraction in the normal human left ventricle.

The sequence for the onset of segmental contraction of the left ventricle was studied in 25 normal patients by analyzing sequential frames obtained at 16.7-msec intervals of right anterior oblique (RAO) ventriculograms by two independent methods. In the first method, we compared the times of onset of contraction of the hemidiameters associated with each of 54 segments with time of onset of contraction of the average of all the hemidiameters for the ventricular contour. In the second method we used a radial coordinate system and determined relative phase relationships by plotting the motion of each of 54 segments against the average motion of all segments. The resulting pattern showed that, on the average, the midregion of the inferior wall began to contract 25 msec before the apex and the midregion of the anterior wall began contraction 18 msec before the apex. In 12 of 25 patients the interior and anterior walls both began to contrast before the apex. In only one of 25 patients did the apex begin to contract first. This sequences of contraction corresponds to the reported sequence of electrical activation for normal human left ventricles.

Heart Ventricles↗
PubMed1978

The specificity of pyrophosphate myocardial scintigrams in patients with prior myocardial infarction: concise communication.

Fifty-five patients with old (9 days to 10 yr) transmural infarcts but with no evidence of recent infarction, were imaged with Tc-99m pyrophosphate. Discrete uptake was rare in the setting of an old infarct. Diffuse uptake was neither sensitive to, nor specific for, acute infarction. Prior infarction will rarely cause diagnostic error if the discrete pattern is required for a positive diagnosis.

Acute Disease↗
PubMed1977

The application of radionuclide infarct scintigraphy to diagnose perioperative myocardial infarction following revascularization.

To evaluate the application of radionuclide infarct scintigraphy to diagnose myocardial infarction after revascularization, we obtained postoperative technetium 99m pyrophosphate myocardial scintigrams, serial electrocardiograms and CPK-MB isoenzymes in ten control and 51 revascularized patients. All control patients had negative electrocardiograms and scintigrams, but eight had positive isoenzymes. Eight revascularized patients had positive electrocardiograms, images and enzymes and two had positive scintigrams and enzymes with negative electrocardiograms. Thirty-four patients with negative electorcardiograms and scintigrams had positive isoenzymes; in only seven patients were all tests negative. Our data suggest radionuclide infarct scintigraphy is a useful adjunct to the electrocardiogram in diagnosing perioperative infarction. The frequent presence of CPK-MB in postoperative patients without other evidence of infarction suggests that further studies are required to identify all factors responsible for its release.

Adult↗
PubMed1976

The similarity of changes in segmental contraction patterns induced by postextrasystolic potentiation and nitroglycerin.

Despite a fundamental difference in their underlying mechanisms, both postextrasystolic potentiation (PESP) and administration of nitroglycerin (TNG) have been utilized to predict reversibility of abnormal segmental wall motion in patients with ischemic heart disease. To determine whether these interventions induce the same changes in segmental contraction pattern, we analyzed biplane ventriculograms of 14 patients who had an adequately visualized PESP beat on a basal ventriculogram as well as a post-TNG ventriculogram. Four segments in each plane were defined and the area ejection fraction of each segment was calculated for a basal sinus, PESP, and post-TNG beat. To correct for global differences in the response to PESP and TNG, we normalized each segmental ejection fraction (NSEF) by the ventricular ejection fraction for that beat and then compared the differences in NSEF from the basal value after PESP and TNG. Eleven patients demonstrated similar responses to both interventions. The three patients whose responses were discordant had elevated or unchanged left ventricular systolic or end-diastolic pressures at the time of the TNG ventriculogram. Our data suggest that, provided these pressures are lower than basal values at the time of the TNG ventriculogram, PESP and TNG will induce similar changes in segmental contraction patterns. Seven patients with similar responses had a PESP beat on their post-TNG ventriculogram. Changes in NSEF after PESP+TNG were identical to those after either intervention. This implies that the combination of interventions does not induce further changes in segmental contraction pattern beyond that produced by either intervention alone.

Angiocardiography↗
PubMed1976

Combination vasodilator therapy for severe chronic congestive heart failure.

A patient with severe, chronic congestive heart failure was unresponsive not only to conventional therapy, but also to nonparenteral nitroglycerin and isosorbide dinitrate; he became nitroprusside dependent. Oral minoxidil therapy produced a significant decrease in systemic vascular resistance and an increase in cardiac output, with no tachycardia, hypotension, or decrease in systemic and pulmonary venous pressures. The addition of sublingual isosorbide dinitrate decreased venous pressures and produced a further increase in cardiac output. The combination of oral minoxidil and sublingual isosorbide dinitrate maintained clinical and hemodynamic improvements, and the patient could be weaned off nitroprusside. Deterioration in hemodynamics occurred with the withdrawal of minoxidil. Therapy with oral hydralazine produced hemodynamic effects comparable to those of oral minoxidil. These observations suggest that chronic reduction of impedance to left ventricular ejection with minoxidil or hydralazine is possible in patients with severe intractable heart failure and deserves further clinical trial.

Chronic Disease↗
PubMed1975

Echocardiographic demonstration of early mitral valve closure in severe aortic insufficiency. Its clinical implications.

Severe aortic insufficiency may accelerate mitral valve closure. We noted this echocardiographic finding in several patients with the acute onset of severe aortic insufficiency. Accordingly, we examined our total echocardiographic series retrospectively for early closure of the mitral valve (ECMV) in the setting of aortic insufficiency and found it in 11 of 53 patients with confirmed aortic insufficiency. During our study ECMV was fortuitously found in two other patients without aortic insufficiency, ECMV occurred in late diastole following the echocardiographic "A" wave, often associated with s suppressed "A" wave (type "B" ECMV). ECMV presence and subtype, along with other clinical parameters, appeared to be useful in the serial evaluation of the patient with severe aortic insufficiency. Additionally, the analysis of ECMV type helped to clarify the mechanism and significance of the Austin Flint murmur. Analysis of 17 patients with and without ECMV, with severe aortic insufficiency judged clinically (NYHA functional class III or IV) and angiographically (3+), indicated that only ECMV patients had acute aortic insufficiency and demonstrated diminished left ventricular size following successful aortic valve replacement. Although due primarily to aortic insufficiency, ECMV could be influenced by rhythm or conducted abnormalities, co-existent cardiac lesions, and pharmacologic interventions. Exclusive of these factors, ECMV was an excellent sign of acute, torrential aortic insufficiency, and a simple noninvasive indicator of the patient requiring immediate aortic valve replacement.

Adolescent↗
PubMedDate not supplied

The electrophysiologic effects of nicardipine hydrochloride in man.

Nicardipine hydrochloride is an investigational antianginal calcium channel blocking agent with potent vasodilating properties. To study its acute electrophysiological effects in man, 12 patients (mean age 66, range 58-84), 6 with normal conduction and 6 with bifascicular block were evaluated. Each subject underwent electrophysiologic studies before and after a bolus and an intravenous infusion of nicardipine titrated to lower the mean blood pressure by at least 10%. The actual drop in mean blood pressure was 17% (p less than .01). The mean bolus was 2.2 +/- 1.2 mg (mean +/- standard deviation). The infusion rate was .21 +/- .06 mg/min. The drop in mean blood pressure was associated with an increase in heart rate of 13% (p less than .01). Maximum sinus node recovery time and sinoatrial conduction time decreased (p less than .01). The QT interval decreased (p less than .01), although the corrected QT remained unchanged. There was a tendency for a decrease in the atrioventricular nodal effective refractory period, functional refractory period, paced atrioventricular and ventriculoatrial conduction times. Intra-atrial, intraventricular and infranodal conduction times did not change. The administration of intravenous nicardipine produces hemodynamic effects consistent with arteriolar vasodilatation and a reflex sympathetic increase in heart rate. Except for the changes in sinus node function, the lack of marked electrophysiologic effects with intravenous nicardipine suggests that reflex sympathetic activity masks its direct slow channel blocking electrophysiologic effects in man.

Aged↗