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Biomedical subjects

M M Bodenheimer

Publications and source records attributed to M M Bodenheimer.

At least 19 recordsLinked to original sources
PubMed1992

Risk stratification in coronary disease: a contrary viewpoint.

Noninvasive stress testing is generally recommended to detect patients who are at increased risk for cardiac death and myocardial infarction. Such tests depend on the presence of a physiologically significant coronary stenosis to detect disease. The low prevalence of events in patients who are able to exercise, however, results in a poor positive predictive value. Also, recent data suggest that a significant number of morbid events result from rapid progression of disease in segments of the coronary artery that initially had only minimal obstruction. Further, from a therapeutic standpoint, only catheterization has been shown in randomized trials to predict which patients are candidates for bypass surgery. Thus, noninvasive testing as an intermediate step to select those patients who require invasive study remains an attractive but unproven hypothesis.

Coronary Disease↗
PubMed1992

Early and rapid prediction of patency of the infarct-related coronary artery by using left ventricular wall thickness as measured by two-dimensional echocardiography.

OBJECTIVES: The aim of this study was to determine whether echocardiography can distinguish between persistent coronary occlusion and reperfusion. BACKGROUND: There are no adequate clinical or noninvasive laboratory markers to accurately predict successful reperfusion in an acute myocardial infarction. METHODS: In a closed chest swine model, the effect of reperfusion on myocardial wall thickness was studied by comparing a 150-min total coronary artery occlusion (group 1) with 120 min of occlusion followed by 30 min of reperfusion (group 2) in the area of risk as measured by echocardiography. Wall thickness was measured at baseline and at 90 and 150 min. RESULTS: In group 1 (n = 4), there was no appreciable change in mean wall thickness from 90 min to 150 min of occlusion at either end-diastole or end-systole (0.54 +/- 0.02 to 0.52 +/- 0.03 cm, 0.55 +/- 0.03 to 0.54 +/- 0.03 cm, respectively; p = NS). In contrast, in group 2 (n = 6), an increase in mean wall thickness from 0.53 +/- 0.02 to 0.97 +/- 0.05 cm at end-diastole and from 0.56 +/- 0.04 to 1.04 +/- 0.07 cm at end-systole was found from 90 min of occlusion to 30 min of reperfusion (p < 0.001). Reperfusion resulted in an increase in wall thickness of 83 +/- 11% at end-diastole and 92 +/- 17% at end-systole. In contrast, persistent coronary occlusion showed minimal changes of -3.0 +/- 5% at end-diastole and -2.0 +/- 6% at end-systole. CONCLUSIONS: This study confirms the hypothesis that an increase in wall thickness can accurately distinguish between reperfusion and permanent coronary occlusion.

Animals↗
PubMed1991

Bypass surgery for chronic stable angina: predictors of survival benefit and strategy for patient selection.

The variable mortality risk associated with chronic stable angina calls for careful selection of patients for coronary artery bypass grafting (CABG) if the aim of management is to prolong life. The randomized and observational studies done in the last 20 years have identified the variables relevant to patient selection and thus have provided a rational basis for such clinical decisions. These studies showed that the sicker the patient, as gauged by relevant measures of coronary disease and cardiovascular morbidity, the more likely it is that CABG will prolong life. A CABG-related improvement in survival is therefore more likely to occur the worse the left ventricular function; the greater the number of diseased vessels; the more proximal the location of coronary lesions (more muscle is threatened by such lesions); the greater the severity of the lesions as determined by angiography; the more severe the angina; the more easily provocable the ischemia or the more extreme the measures of ischemia; and, within limits, the older the patient. Greater survival gain after CABG also occurs in patients with peripheral vascular disease, in patients with baseline electrocardiographic ST-segment and T-wave changes, and probably in women. Thus, patients are likely to live longer after CABG if they have left main disease; three-vessel disease with left ventricular dysfunction (ejection fraction less than 50%), class III or IV angina, provocable ischemia, or disease in the proximal left anterior descending coronary artery; two-vessel disease with proximal left anterior descending artery involvement; and two-vessel disease with class III or IV angina as well as either severe left ventricular dysfunction alone or moderate left ventricular dysfunction together with at least one proximal lesion. When the decision of whether to do CABG is less clear-cut, the presence of peripheral vascular disease, female sex, baseline electrocardiographic ST-segment and T-wave changes, or older age (over 60 but under 80 years) should weigh in favor of doing CABG. In general, patients with single-vessel disease do not seem to derive survival benefit from CABG.

Angina Pectoris↗
PubMed1991

Global analysis of myocardial isotonic shortening: comparison with isometric dynamics.

Although potentially analytically useful, a global empirical model of the myocardial isotonic curve, L(t), has not been described. We propose the following relation: L(t) = C(t/A)B-1e-(t/A)B, where A, B, and C are global parameters, L is length, and t is time. We evaluated this model in nine in situ canine papillary muscles studied with a servo-system to produce isotonic twitches at different isotonic forces (F). For each twitch, the parameters were determined by nonlinear curve fitting. The model fit the observed curves of L(t) closely, with the coefficient of determination being 0.995 +/- 0.002. C changed with F, but A and B varied little with F, averaging 0.262 +/- 0.021 s and 2.76 +/- 0.17, respectively. Our predictions that A reflects chronotropic, B reflects lusitropic, and C reflects heterotonic (different afterloads) and inotropic states were supported. Comparison done in five muscles showed that A was the same but B was higher for isotonic than for isometric twitches: 0.270 +/- 0.020 vs. 0.264 +/- 0.038 s (P = not significant) for A and 2.79 +/- 0.18 vs. 2.39 +/- 0.05 (P less than 0.008) for B. Dobutamine increased A but not B in isotonic twitches. Thus shortening is lusitropic but leaves no lusitropic reserve to be mobilized by dobutamine. The relation L(t) = C(t/A)B-1e-(t/A)B provides a framework that undergirds global analysis of myocardial shortening and enables comparison with isometric dynamics.

Animals↗
PubMed1991

Effect of coronary occlusion and myocardial viability on myocardial activity of technetium-99m-sestamibi.

The timing effect of sestamibi administration with respect to the onset of myocardial ischemia and reperfusion was studied in swine. In different groups of animals sestamibi was administered prior to coronary artery occlusion, during occlusion, or 1/2 hour following reperfusion. Sestamibi administered prior to coronary occlusion resulted in an insignificant decrease in 99mTc activity in the ischemic zone. However, infarct zone activity was reduced to 62 +/- 14% of the nonischemic zone. In contrast, administration during coronary occlusion resulted in similar significant reductions of both ischemic and infarct zone activity. Administration of sestamibi during reperfusion resulted in normal ischemic zone activity and markedly reduced activity in the infarct zone. Significantly reduced activity in the infarct zone was found to be independent of the timing of sestamibi administration with respect to the onset of myocardial ischemia and/or reperfusion. Thus, cell viability appears required for uptake and retention of isotope activity.

Animals↗
PubMed1990

Effect of early reperfusion on use of triphenyltetrazolium chloride to differentiate viable from non-viable myocardium in area of risk.

STUDY OBJECTIVE - The aim of the study was to assess the value of triphenyltetrazolium chloride (TTC) staining as an indicator of non-viable myocardium after early reperfusion of ischaemic myocardium. DESIGN - Left anterior descending artery occlusion was performed in pigs for various lengths of time and at two different sites (proximal and distal). After 120 min reperfusion, TTC was injected distal to the occlusion while the remainder of the myocardium was stained with Evans Blue. Myocardial enzymes were measured in non-ischaemic zone, regions of risk and in necrotic zones and related to staining characteristics. SUBJECTS - 31 male Hampshire pigs, weight 34-39 kg, were studied. Twelve were excluded because of resistant ventricular fibrillation or poorly defined areas of infarction. In the remaining 19 pigs, proximal occlusion was carried out in 15 and distal in four. Occlusion lasted for 15 min in six animals, for 30 min in eight (four of which were the animals with distal occlusions), and for 45 min in five. MEASUREMENTS and RESULTS - Biopsies from non-ischaemic zones, regions of risk and necrotic zones were analysed for creatine kinase and lactate dehydrogenase. In the 15 min group, myocardial creatine kinase in the region of risk (red stained) was similar to the non-ischaemic (blue) zone, but in the 30 min distal occlusion group it was reduced. After 30 and 45 min of proximal occlusion, creatine kinase activity in the necrotic (white) zone was reduced compared to the red zone in the same group, and in the red zone of both groups it was reduced compared to the non-ischaemic area. CONCLUSIONS - The red zone, as defined by TTC staining, may be associated with significant creatine kinase depletion after relatively brief periods of occlusion and subsequent reperfusion. This suggests that the red region may be a heterogeneous area of dead and viable cells.

Animals↗
PubMed1990

Limited correlation of left ventricular end-diastolic pressure with radiographic assessment of pulmonary hemodynamics.

Left ventricular end-diastolic pressure (LVEDP) is a reliable indicator of the diastolic function of the left ventricle. The purpose of this study was to correlate the radiographic assessment of pulmonary hemodynamics with LVEDP. The study population consisted of 104 consecutive patients with four categories of LVEDP: less than 13 mm Hg (n = 26), 13-19 mm Hg (n = 30), 20-24 mm Hg (n = 24), and more than 24 mm Hg (n = 24). Chest radiographs obtained within 24 hours of cardiac catheterization were assessed for evidence of congestive heart failure (CHF) by three experienced radiologists. Findings were graded from 0 to 3 (normal to abnormal) on the basis of the following signs of CHF: redistribution, perihilar and perivascular haze, peribronchial cuffing, pulmonary artery-bronchus ratio, septal lines, subpleural edema, air-space edema, pleural effusion, cardiomegaly, and overall radiographic assessment of CHF. A consensus report was then generated. In patients with LVEDP over 20 mm Hg, 38% did not show CHF in the overall assessment. Correlation between radiographic signs of CHF and LVEDP was limited.

Cardiac Catheterization↗
PubMed1989

Analysis of myocardial isometric dynamics using parameters of a global model.

Despite previous efforts, a global empirical relation has not been described for the myocardial isometric curve, F(t). We propose here that a useful relation is F(t) = CtB-1e-AtB. A, B, and C are global parameters. We evaluated this model and the effect of change in muscle length (L) and dobutamine on the parameters in nine in situ canine papillary muscles. A servo-system clamped muscle length to produce isometric twitches. For each twitch, the parameters were determined by curve fitting. The model fit the observed curves of F(t) closely; the correlation coefficient was 0.997 +/- 0.001. Whereas C changed with L, A and especially B varied little with L averaging 28.6 +/- 5.2 and 2.42 +/- 0.08, respectively. Our predictions that A reflects chronotropic state, B lusitropic, and C heterometric and inotropic states, were verified with dobutamine. We also derived relations for various attributes of the F(t) curve in terms of A, B, and C only. An excellent correlation was noted between the calculated and the observed values of these attributes. The empirical relation F(t) = CtB-1e-AtB therefore provides a valid cohesive reference frame for analysis of myocardial dynamics.

Animals↗
PubMed1989

Differences in left ventricular adaptation to chronic mitral and aortic regurgitation.

For comparable volume load, impedance to ejection of the regurgitant volume in AR exceeds that in MR. To determine whether this load difference results in differences in PLVH and ejection performance, we studied consecutive, untreated, asymptomatic patients (11 in each group) by echocardiography and Doppler. Mean LVID, SBP, h, and FS were, respectively, in AR vs MR: 60.3 +/- 3.1 mm vs 62.0 +/- 2.3 mm (p = NS), 152 +/- 7.1 mm Hg vs 125 +/- 6.4 mm Hg (p less than 0.005), 12.1 +/- 0.4 mm vs 10.5 +/- 0.6 mm (p less than 0.04), and 0.38 +/- 0.02 vs 0.43 +/- 0.02 (p = NS). The h/R ratio reflects the PLVH-0.41 +/- 0.02 in AR and 0.34 +/- 0.02 in MR (p less than 0.02). The FS correlates positively with h/R in either lesion, but was higher in MR for any given h/R. The difference in loading conditions imposed by both lesions is associated with a difference in the PLVH as well as in ejection performance.

Adaptation, Physiological↗
PubMed1988

Comparative bioavailability of two oral sustained-release procainamide products.

The bioavailability characteristics of two sustained-release oral procainamide preparations, Procan SR and Pronestyl-SR, were compared in 10 patients with arrhythmias. Each patient was randomly assigned to receive either Procan SR 1 g or Pronestyl-SR 1 g, both administered orally every six hours. The initial drug was continued for 48 hours (eight doses), at which time the second drug, given at the same dosage and dosing interval, was substituted for a 48-hour period. Serum samples for procainamide determination were obtained hourly between 42 and 48 and between 90 and 96 hours after initiation of procainamide therapy. Values for area under the serum concentration-time curve (AUC) during the steady-state dosing interval, maximum serum drug concentration (Cmax), minimum serum drug concentration (Cmin), Cmax:Cmin ratio (representing fluctuations in serum drug concentrations within the dosing interval), and the time to maximum serum drug concentration (tmax) were determined. Mean ( +/- S.D.) tmax values for Procan SR and Pronestyl-SR were 2.2 +/- 0.8 hours and 3.8 +/- 1.1 hours, respectively. Only the differences between tmax values were statistically significant. The study had an 83% chance of detecting a 20% difference in AUC values. The chances of detecting a 20% difference in values for Cmax and Cmin were 62% and 71%, respectively. These two preparations would probably possess similar therapeutic properties when given at the same dosage and dosing schedule; however, studies with larger subject populations are needed to project bioavailability data to the general population.

Aged↗
PubMed1987

Role of exercise thallium-201 myocardial perfusion scintigraphy in predicting prognosis in suspected coronary artery disease.

While exercise thallium imaging has improved sensitivity and specificity for detection of coronary artery disease (CAD), its predictive value for morbid cardiac events is unclear. Of 532 consecutive patients who underwent exercise thallium imaging, follow-up was complete in 515 (97%) after an average of 36 months (range 31 to 48). Two hundred six patients had an abnormal exercise thallium response and 309 had a normal response. Twenty morbid cardiac events occurred (13 deaths and 7 acute myocardial infarctions [AMI]). Of the 13 patients who died, 12 had abnormal thallium results. Overall, 5.8% of the patients with abnormal thallium results died, in contrast to 0.3% of patients with normal results. Of the 7 patients who had a nonfatal AMI, 3 had abnormal exercise thallium results. Moreover, similar proportions of patients (1.4% and 1.3%) with normal and abnormal exercise thallium results had nonfatal AMI. Presence or absence of pathologic Q waves and inclusion of exercise electrocardiographic results did not significantly alter the results. Thus, although a normal exercise thallium response significantly reduces the likelihood of cardiovascular death, its predictive value for nonfatal AMI is limited. Moreover, the relatively low event rate for patients with a positive exercise thallium response further limits its prognostic value.

Coronary Circulation↗
PubMed1986

The impact of transtelephonic documentation of arrhythmia on morbidity and mortality rate in sudden death survivors.

A post hospital follow-up system based on predetermined antiarrhythmic strategies and telephone transmitters used to record ECGs was helpful in managing post hospital course and improved survival in patients with a history of out-of-hospital sudden death. All patients underwent therapy guided by serial electrophysiologic testing. Of the 47 patients, 19 used the telephone transmitter system and 28 did not. During follow-up, residual symptomatic and silent ventricular arrhythmia was documented in 78% of patients using telephone transmitters. Ventricular tachycardia was transmitted in six patients--all survived. During an average 15-month follow-up, 1 of 19 patients using the telephone transmitter system died vs 12 deaths among the 28 patients who did not use the system (p less than 0.005). These results were independent of ejection fraction, presence of congestive heart failure, amiodarone therapy, and the outcome on electrophysiologic therapy. Thus, patients with a history of out-of-hospital sudden death, discharged following electrophysiologic guided therapy, require repeated antiarrhythmic dose titration for side effects or residual ventricular arrhythmia. Prompt diagnosis and treatment of potentially fatal arrhythmia is crucial and feasible, especially with regular ECG checks through telephone transmission.

Anti-Arrhythmia Agents↗
PubMed1986

Quantitation of absolute area of a coronary arterial stenosis: experimental validation with a preparation in vivo.

The absolute cross-sectional area of a coronary stenosis measured by quantitative coronary angiography correlates well with its hemodynamic significance. We evaluated a combined approach using edge detection applied to the normal segment and videodensitometry applied to the stenosis to determine the absolute cross-sectional area of the stenosis (videodensity method). The results were then compared with those with the edge detection method applied directly to the stenosis. The area of the stenosis by the edge detection method was calculated by analyzing two orthogonal projections for irregular stenoses and with use of the formula for the area of an ellipse (ellipse method). The accuracy of both these techniques was assessed by analyzing digital angiograms acquired from closed-chest dogs in which 10 plastic cylinders with precisely machined circular and irregular lumina were inserted into the coronary arteries. Angiograms of irregular stenoses were acquired in two orthogonal views. The ellipse method applied to circular stenoses was very accurate, with r = .97, average absolute difference (AAD) = 0.21 mm2, and SEE = 0.30. For the videodensity method r = .97, AAD = 0.84 mm2, and SEE = 0.40. Irregular stenoses were better quantitated by the videodensity method applied in one view (AAD = 0.50 mm2, SEE = 0.47) than by the ellipse method applied in two orthogonal projections (AAD = 1.03 mm2, SEE = 0.87). Overall, the two methods were comparable in accuracy (for videodensity, AAD = 0.65 mm2, SEE = 0.71 vs AAD = 0.54 mm2, SEE = 0.79 for ellipse).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1985

A sequential approach to the diagnosis of coronary artery disease using multivariate analysis.

There has been considerable interest in recent years in enhancing the accuracy of noninvasive tests in diagnosing coronary artery disease. The recognition that no currently available test is a perfect predictor has led to the use of probability analysis as a means of assessing the presence or absence of coronary disease. In this article we present a multivariate approach to the diagnosis of coronary disease. One hundred forty-seven patients undergoing coronary angiography, thallium-201 imaging, and exercise ECG were studied. Patients were classified according to age, sex, and typical vs atypical chest pain. Sequential stepwise logistic regression analysis was performed to develop probability statements prior to testing, after exercise ECG, and after exercise ECG and thallium-201. The results indicate that this sequential approach can be used to develop strategies for the diagnosis of coronary disease in the same way as Bayes' theorem, while permitting integration of multiple characteristics into one model.

Adult↗
PubMed1985

Influence of nitroglycerin on collateral blood flow during acute ischaemia in the dog.

To investigate the effects of nitroglycerin on collateral blood flow 10 open chest dogs underwent coronary occlusion followed by nitroglycerin infusion (80 to 300 micrograms . min-1) to lower mean systemic blood pressure by 20 mmHg, followed by phenylephrine infusion (10 to 40 micrograms . min-1) to restore blood pressure to the pre-nitroglycerin level. Myocardial blood flow was measured with microspheres. The contribution of overlapping normal zone tissue in the ischaemic zone was evaluated with the balloon perfusion technique. Collateral flow was measured with microspheres in the most ischaemic tissue. In addition "load line" analysis was used to calculate collateral flow from retrograde flow. Nitroglycerin lowered blood flow to non-ischaemic tissue, and tended to lower blood flow to ischaemic tissue. Phenylephrine restored blood flow to the value after coronary occlusion. Load line analysis data was similar to data on myocardial blood flow from the microspheres. Collateral resistance changed little during the experiment. Th effects of nitroglycerin on collateral blood flow are, thus, minimal. While it is possible that under special circumstances there may be some decrease in collateral resistance, the bulk of data from this study and others do not support the idea that systemic infusion of nitroglycerin in the setting of an acute myocardial infarction will affect collateral flow.

Animals↗