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Biomedical subjects

B S Denenberg

Publications and source records attributed to B S Denenberg.

12 recordsLinked to original sources
PubMed1986

Effects of age on ventricular performance during graded supine exercise.

To assess the effects of age on ventricular performance, graded supine exercise tests with equilibrium radionuclide ventriculography were performed in six normal subjects of mean age 37 +/- 4 years and in eight normal subjects with a mean age of 59 +/- 2 years. At a standard submaximal work load, older subjects had a similar heart rate (older: 126 +/- 10, younger: 128 +/- 5 bpm) and systolic blood pressure responses (older: 198 +/- 24, younger: 202 +/- 24 mm Hg). Cardiac output counts increased appropriately in both groups during submaximal exercise. However, when expressed as percent change from resting values, the increases in cardiac output (older: 125 +/- 14, younger: 75 +/- 10 L/min; p less than 0.05) were greater for the older subjects. The percent change in end-diastolic counts (older: 8.4 +/- 5, younger: -2.8 +/- 4), stroke counts (older: 26 +/- 6, younger: 8.6 +/- 4), and ejection fraction (older: 18 +/- 3, younger: 11 +/- 1%) in proceeding from rest to exercise Stage III (600 kg-m/min) was greater for the older subjects. Age-related differences in each of these measurements were significant at p less than 0.05. These findings suggest that cardiac output during exercise is maintained by an increased heart rate in younger subjects, and by a combination of increased heart rate and the Frank-Starling mechanism in older individuals. Since the heart rate and mean blood pressure response to exercise were similar in both groups, the use of the Frank-Starling mechanism during exercise in older subjects suggests that age-related differences in ventricular preload are important in modulating the performance of the aging left ventricle.

Adult↗
PubMed1985

Chronic thyroiditis and mitral valve prolapse.

Mitral valve prolapse is more prevalent in patients with autoimmune diffuse toxic goiter, suggesting a possible etiologic association. The prevalence of mitral valve prolapse was determined in 75 patients with chronic lymphocytic thyroiditis, another autoimmune thyroid disorder, and in 50 healthy control subjects. Mitral valve prolapse was found in 31 of 75 (41%) patients with chronic lymphocytic thyroiditis and in 4 of 50 (8%) controls (odds ratio, 8.10; 95% confidence interval, 2.64 to 24.83; p less than 0.0005). The age-race adjusted odds ratio was 9.26 (95% confidence interval, 2.83 to 30.26; p less than 0.0005). No correlation between the prevalence of mitral valve prolapse and the presence of hypothyroidism, serum antithyroid antibodies, or the duration of chronic lymphocytic thyroiditis was found. The prevalence of mitral valve prolapse is substantially increased in patients with the autoimmune thyroid disorders.

Adult↗
PubMed1984

Coronary thrombolysis by intravenous streptokinase in acute myocardial infarction: acute and follow-up studies.

Coronary arteriography was performed before, immediately after, and 9 to 14 days after administering i.v. streptokinase (850,000 to 1,500,000 IU) to 43 patients within 6 hours of myocardial infarction. Ventricular function was determined by contrast ventriculography before and 9 to 14 days later and by radionuclide studies at clinical follow-up 8 months later. Early reperfusion occurred in 49% of patients, but in only 35% was it sustained. In patients with sustained reperfusion, early ventricular dysfunction was significantly reduced 9 to 14 days and 10 months later, and frequency of infarction, sudden death, and angina pectoris was not increased at follow-up. No serious bleeding occurred.

Adult↗
PubMed1984

Absolute left ventricular volume by an iterative build-up factor analysis of gated radionuclide images.

A method for determining absolute left ventricular (LV) volumes from radionuclide gated blood-pool (GBP) images was validated in 34 patients. The technique is nongeometric, corrects for tissue attenuation, and uses an experimentally determined set of build-up factors to account for the effects of scatter. Only four parameters are needed to determine LV volumes: the LV count rates from a left anterior oblique (LAO) and a right posterior oblique (RPO) image (180 degrees opposed to the LAO), a venous blood sample, and a patient thickness measurement. A computer algorithm is used to reach an iterative solution to two simultaneous equations that yield LV volumes. Phantom studies showed less than 4% error for volume determinations at all investigated depths. For the patients studied the correlation between volumes obtained by GBP and contrast ventriculography was 0.97 for diastole and 0.96 for systole.

Adult↗
PubMed1984

Assessment of systolic ventricular muscle function in man: the end systolic index.

Accurate assessment of ventricular muscle contractile function in patients with heart disease is impaired by alterations in afterload, preload and wall thickness which often accompany the disease. The relationship between pressure and volume at end systole is considered to provide a contractile index which is independent of preload and which accounts for afterload. Use of the index prerequisites determinations of the left ventricular end systolic pressure, wall thickness as well as the dimensions or volumes, respectively, which may be assessed with either invasive or noninvasive methods. In patients with aortic stenosis and congestive heart failure, there was a significantly reduced slope (0.9 +/- 0.5) of the end systolic stress-volume relationship as compared with healthy subjects (5.8 +/- 1.3) or patients with aortic stenosis without congestive heart failure (3.9 +/- 1.3), while the ejection fraction showed no significant differences. In patients with mitral regurgitation with no or only minimal symptoms postoperatively, preoperatively the end systolic index (ESS/ESVI) was higher (3.3 +/- 0.4) than in patients with marked symptoms postoperatively or those who died perioperatively (2.2 +/- 0.2) and the values of both patient groups were lower than those of normals. In contrast, the values for ejection fraction among the normals and both groups of patients showed substantial overlap. In patients with aortic insufficiency and congestive heart failure, as opposed to patients with aortic insufficiency and only slight symptoms, there was a significantly compromised ejection fraction as well as diminished end systolic index (ESS/ESVI). Patients with hypertension accompanied by congestive heart failure had a significantly diminished slope of the relationship between end systolic left ventricular stress and volume while the values for hypertensive patients without congestive heart failure were within normal limits; in both groups of patients, the ejection fraction was normal. In patients with mitral stenosis, the end systolic index at 5.28 +/- 0.53 did not differ significantly from that of healthy subjects at 4.87 +/- 0.53, while the velocity of circumferential fiber shortening was diminished. Patients with large atrial septal defects and symptoms of congestive heart failure did not differ with respect to end systolic index or ejection fraction as compared with atrial septum defect patients without symptoms. In children with aortic stenosis and high pressure gradients, there was an increased ejection fraction together with a normal end systolic index.(ABSTRACT TRUNCATED AT 400 WORDS)

Anemia, Sickle Cell↗
PubMed1983

Absolute left ventricular volume from gated blood pool imaging with use of esophageal transmission measurement.

A new method for determining absolute left ventricular (LV) volume from equilibrium gated blood pool images was validated in 36 patients by comparing gated blood pool (GBP) imaging with contrast ventriculography (CV) using both Simpson's rule (SR) and area-length (AL) calculations. The technique is geometry-independent and is the first to correct for tissue attenuation with use of an in vivo point source. An orally administered capsule containing 1 to 2 mCi of technetium-99m (Tc-99m) sulfur colloid is used for this purpose. Left ventricular volumes are determined by dividing attenuation and background-corrected count rates obtained from semiautomated LV regions of interest by the count rate per milliliter from a blood sample. The correlation between GBP and CV (SR) was 0.96 (CV [SR] = 0.99 GBP + 1.32 ml; standard error of the estimate [SEE] = 21.2 ml) for diastole and 0.97 (CV [SR] = 0.93 GBP - 0.03 ml; SEE = 11.9 ml) for systole. The correlation between GBP and CV (AL) was 0.92 (CV [AL] = 0.90 GBP + 16.72 ml; SEE = 27.8 ml) for diastole and 0.95 (CV [AL] = 0.87 GBP + 4.56 ml; SEE = 14.4 ml) for systole. The method is noninvasive and can be performed easily as part of routine gated blood pool imaging and analysis.

Adult↗
PubMed1983

Cardiac function in sickle cell anemia.

Although ventricular dysfunction is suspected to underlie congestive heart failure in sickle cell anemia (SCA), ejection indexes of left ventricular (LV) pump performance have been found to be normal. The increased preload and decreased afterload of SCA increases the ejection phase indexes and might obscure true LV dysfunction. Therefore, the preload and afterload independent end-systolic stress-volume index was compared in 11 patients with SCA and in 11 normal volunteers. End-systolic pressure and echocardiographic LV dimensions were determined during rest, leg raise, hand-grip and amyl nitrite inhalation. Systemic vascular resistance (afterload) was decreased to 1,033 +/- 314 dynes s cm-5 (mean +/- standard deviation) in SCA from 1,701 +/- 314 dynes s cm-5 in normal subjects. End-diastolic volume index (preload) was increased to 102 +/- 24 ml/m2 in SCA from 66 +/- 10 ml/m2 in normal subjects. Cardiac index was increased to 4.7 +/- 1.1 liters/min/m2 in SCA from 2.8 +/- 0.8 liters/min/m2 in normal subjects. Ejection fractions were similar: 0.59 +/- 0.09 in SCA versus 0.62 +/- 0.07 in normal subjects. However, in patients with SCA, the ratio of resting end-systolic stress-volume index was decreased (1.5 +/- 0.5 in SCA versus 2.8 +/- 0.6 in normal subjects) and the slope of the end-systolic stress versus end-systolic volume index relation was decreased (2.7 +/- 1.3 in SCA versus 4.4 +/- 1.8 in normal subjects), suggesting LV dysfunction in those patients. Thus, LV muscle contractile performance is depressed in SCA. Increased preload and decreased afterload compensate for the LV dysfunction and maintain a normal ejection fraction and high cardiac output.

Adolescent↗
PubMed1983

Multiple scintigraphic findings in a patient with a primary myocardial sarcoma.

Primary myocardial sarcomas are rare. We report the scintigraphic findings observed with TI-201, Ga-67, Tc-99m pyrophosphate, and Tc-99m pertechnetate labeled red cell gated cardiac imaging in a patient with this tumor. We found that thallium and gated blood pool imaging can be used both in the diagnosis of these tumors and the assessment of the effects of chemotherapy on the tumor and normal myocardium. The thallium study was particularly helpful in identifying the malignant nature of the tumor by showing extensive infiltration into surrounding areas.

Adult↗
PubMed1982

High-dose, brief intravenous streptokinase early in acute myocardial infarction.

An acute thrombus at the proximal border of a high-grade atherosclerotic obstruction is the usual cause of myocardial infarction. Although intracoronary thrombolysis is potentially an exciting new therapy for reducing the extent of myocardial infarction by lysing coronary clot, a number of major difficulties limit its widespread application. It is a complex procedure requiring intracoronary visualization and infusion within a few hours of onset of symptoms. Since intravenous streptokinase could be widely applied if effective, we and others have wondered whether high-dose, brief-duration intravenous streptokinase infusion given early in myocardial infarction would lyse coronary clots without bleeding. To date we have treated 13 patients within 6 hours of onset of symptoms and with ECG and angiographic evidence of typical myocardial infarction caused by coronary clot. Clot lysis and angiographically proved coronary reperfusion were achieved in 6 patients within 1 hour of starting a systemic intravenous infusion of 850,000 IU of streptokinase. Schroeder et al., in Berlin, West Germany, achieved angiographically proved coronary reperfusion in 11 of 21 patients with acute myocardial infarction following a 30-minute intravenous streptokinase infusion of 500,000 IU. Neuhaus et al., in Göttinen, West Germany, achieved angiographically proved coronary reperfusion in 24 of 39 similar patients within 48 minutes by intravenous infusion of 1,700,000 IU of streptokinase. In these three studies, no serious bleeding occured; left ventricular function was improved in patients who achieved coronary reperfusion. We conclude that rapid intracoronary clot lysis and coronary reperfusion can be achieved early in myocardial infarction by brief-duration systemic intravenous infusion of high-dose streptokinase without a high incidence of serious bleeding.

Clinical Trials as Topic↗
PubMed1981

Normal left ventricular emptying in coronary artery disease at rest: analysis by radiographic and equilibrium radionuclide ventriculography.

The volume ejected early in systole has been proposed as an indicator of abnormal left ventricular function that is present at rest in patients with coronary artery disease with a normal ejection fraction and normal wall motion. The volume ejected in systole was examined by calculating the percent change in ventricular volume using both computer-assisted analysis of biplane radiographic ventriculograms at 60 frames/s and equilibrium gated radionuclide ventriculograms. Ventricular emptying was examined with radiographic ventriculography in 33 normal patients and 23 patients with coronary artery disease and normal ejection fraction. Eight normal subjects and six patients with coronary artery disease had both radiographic ventriculography and equilibrium gated radionuclide ventriculography. In all patients, there was excellent correlation between the radiographic and radionuclide ventricular emptying curves (r = 0.971). There were no difference in the ventricular emptying curves of normal subjects and patients with coronary artery disease whether volumes were measured by radiographic or equilibrium gated radionuclide ventriculography. It is concluded that the resting ventricular emptying curves are identical in normal subjects and patients with coronary artery disease who have a normal ejection fraction and normal wall motion.

Contrast Media↗
PubMed1981

Redistribution on the thallium scan in myocardial sarcoidosis: concise communication.

Resting and redistribution thallium studies were performed in four young patients with sarcoidosis to evaluate the possibility of myocardial involvement. In each case the resting scan showed marked defects that resolved on the redistribution studies. In a different patient population, these results would have implied significant coronary artery disease.

Adult↗