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Biomedical subjects

E H Botvinick

Publications and source records attributed to E H Botvinick.

At least 91 records · Page 5Linked to original sources
PubMed1984

Cardiac imaging using gated magnetic resonance.

To overcome the limitations of magnetic resonance (MR) cardiac imaging using nongated data acquisition, three methods for acquiring a gating signal, which could be applied in the presence of a magnetic field, were tested: an air-filled plethysmograph, a laser-Doppler capillary perfusion flowmeter, and an electrocardiographic gating device. The gating signal was used for timing of MR imaging sequences (IS). Application of each gating method yielded significant improvements in structural MR image resolution of the beating heart, although with both plethysmography and laser-Doppler velocimetry it was difficult to obtain cardiac images from the early portion of the cardiac cycle due to an intrinsic delay between the ECG R wave and peripheral detection of the gating signal. Variations in the temporal relationship between the R wave and plethysmographic and laser-Doppler signals produced inconsistencies in the timing of IS. Since the ECG signal is virtually free of these problems, the preferable gating technique is IS synchronization with an electrocardiogram. The gated images acquired with this method provide sharp definition of internal cardiac morphology and can be temporarily referenced to end diastole and end systole or intermediate points.

Animals↗
PubMed1984

The scintigraphic identification of "severe myocardial ischemia".

Both perfusion scintigraphy and blood pool scintigraphy have been shown to have a high sensitivity and excellent specificity for the diagnosis of coronary artery disease. Particularly helpful in those patients where the diagnosis remains in doubt or is ambiguous, scintigraphic methods have, previously tended to underestimate the degree of coronary vascular involvement. Identification of patients with main left and triple vessel coronary disease is extremely critical as these lesions have been shown to relate to an extremely high risk in terms of morbidity and mortality and since this risk has been shown to be reduced by invasive treatment. While the extent of stress induced wall motion abnormalities and the degree of functional abnormality induced by stress suggests extensive coronary involvement, quantitative methods of radial analysis and wash-out have been applied to perfusion scintigraphy, providing objectivity and increasing the ability to identify the full extent of vascular involvement. Additionally, nonperfusion scintigraphic indicators as lung uptake, cavitary dilatation and basal uptake have, in the presence of coronary disease, demonstrated a relationship to extensive myocardial ischemia and multivessel disease. Numerous studies have now indicated the increased ability of scintigraphic methods to identify such "high-risk" coronary patients. Furthermore, the pathophysiologic nature of scintigraphic analysis permits the differentiation of the degree of coronary involvement from the true risk factor, the extent of myocardium at ischemic risk. In the setting of myocardial infarction, acute scintigraphic indicators often aid the direction of therapy and provide means for assessment of therapeutic effects. Additionally, scintigraphic measures of the extent of infarction, related ischemia and function have all demonstrated prognostic abilities.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1983

The functional implications of scintigraphic measures of myocardial ischemia and infarction.

To compare serial functional and perfusion scintigraphic changes after myocardial infarction, we performed left ventricular (LV) cineangiograms and thallium (TI)-201 myocardial perfusion scintigrams before and 1 hour, 2 days, 9 days, and 1 month after closed chest coronary occlusion in 14 dogs as survival permitted. Survivors were studied with technetium-99m (stannous) pyrophosphate (TcPYP) scintigrams at 48 hours, and at postmortem examination infarction was documented and measured after nitroblue tetrazolium (NBT) staining. The TcPYP image was abnormal in 10 dogs, each of which had infarcts on NBT staining measuring 3 to 23 gm. In all 14 dogs, perfusion scintigrams became abnormal and LV ejection fraction (EF) fell when measured within 48 hours of occlusion. In the nine late survivors studied over 1 week after the event, perfusion scintigrams and EF improved in those which developed infarcts and normalized in those without infarction. The decrement in LVEF after coronary occlusion generally showed serial improvement and correlated with the size of the defect in the accompanying TI-201 scintigram (r = 0.74). TI-201 defect size seen in late studies correlated well with NBT infarct size (r = 0.89) and TcPYP image infarct size (r = 0.82), as it did with the decrement in LVEF noted in late studies (r = 0.86). The results suggest that early perfusion scintigrams together with TcPYP images may be useful for estimating the amount of reversible dysfunction after coronary occlusion.

Animals↗
PubMed1983

Late prognostic value of scintigraphic parameters of acute myocardial infarction size in complicated myocardial infarction without heart failure.

Perfusion scintigraphy with thallium-201, infarct scintigraphy with technetium-99m pyrophosphate (TcPYP), and equilibrium blood pool scintigraphy were performed during the initial hospitalization for acute myocardial infarction (MI) in 25 patients without evidence of heart failure who presented with advanced electrocardiographic rhythm and conduction disturbances requiring treatment. Scintigraphic findings during short-term hospitalization were related to the late clinical follow-up performed an average of 14 months later, where patients were grouped as asymptomatic, 8 patients; symptomatic, 9 patients; and deceased, 8 patients. Quantitation of perfusion abnormalities, TcPYP image abnormalities, and left ventricular ejection fraction (EF) revealed that the deceased group had significantly larger TcPYP abnormalities (36 +/- 20 cm2), absolute perfusion abnormalities (32 +/- 16 cm2), and perfusion abnormalities expressed as a percentage of the projected left ventricular area (42 +/- 8%) than the asymptomatic group (13 +/- 8 cm2, 14 +/- 6 cm2, and 20 +/- 9%; p less than 0.05, p greater than 0.05, and p less than 0.01, respectively). The percent perfusion abnormality was significantly larger in the deceased group (42 +/- 8%, p less than 0.01) than in either the symptomatic group (35 +/- 13%, p less than 0.01) or the asymptomatic group (20 +/- 9%), and this parameter in the symptomatic group also differed from that in the asymptomatic group (p less than 0.01). The study indicates that patients with rhythm and conduction disturbances and without congestive heart failure during acute MI may follow an uncomplicated or a complicated late clinical course. Early scintigraphic measurements of MI and perfusion correlate well with this outcome; however, EF could not differentiate among prognostic subgroups.

Adult↗
PubMed1983

Electrophysiologic mechanism of exercise-induced sustained ventricular tachycardia.

To elucidate electrophysiologic mechanism of exercise-induced ventricular tachycardia (VT), electrophysiologic studies were performed in 12 patients in whom sustained VT had developed during treadmill exercise testing. Six patients had arteriosclerotic coronary heart disease, 3 had cardiomyopathy, and 3 had no clinical evidence of organic heart disease. All patients had had documented episodes of sustained VT related to exertion and had experienced dizziness, syncope, or both. In addition, 3 patients had had nonfatal cardiac arrest. Electrophysiologic studies provoked paroxysms of sustained VT identical to those observed during treadmill exercise testing in 10 patients and provoked ventricular flutter/fibrillation in 1. Seven patients had VT suggestive of a reentrant mechanism, as the VT could be readily initiated with programmed ventricular extrastimulation or terminated by ventricular overdrive pacing, or both. Three patients had VT suggestive of catecholamine-sensitive automaticity. The VT could not be initiated with programmed electrical stimulation, but it could be provoked by intravenous isoproterenol infusion; furthermore, the VT could not be terminated with ventricular overdrive pacing, but it could be abolished by discontinuing isoproterenol infusion. Reproduction of VT in these 10 patients allowed serial pharmacologic testing in selecting an effective antiarrhythmic regimen. Thus (1) exercise-induced VT can be caused by either reentry or catecholamine-sensitive automaticity, and (2) electrophysiologic studies are of use in defining the underlying mechanism of exercise-induced sustained VT.

Adolescent↗
PubMed1983

Variability in coronary hemodynamics in response to ergonovine in patients with normal coronary arteries and atypical chest pain.

Because an increase in coronary vascular resistance in response to ergonovine maleate has been suggested as a possible diagnostic aid for variant angina, changes were evaluated in coronary hemodynamics and serial myocardial thallium-201 perfusion scans in 15 patients without angina and with normal coronary arteries in response to ergonovine (0.05, 0.10 and 0.20 mg intravenously). For the group, heart rate-blood pressure product increased significantly (p less than 0.001) without any change in coronary sinus flow, coronary vascular resistance, myocardial oxygen extraction, arterial-coronary sinus oxygen difference and lactate extraction. In 7 of 15 patients, however, coronary vascular resistance increased (mean 39%, range 11 to 75%, probability [p] less than 0.001), and coronary sinus flow decreased (14%, p less than 0.001), despite an increase in heart rate-blood pressure product (36%, p less than 0.02). No electrocardiographic, metabolic or thallium-201 scan abnormalities occurred. Therefore, significant increases in coronary vascular resistance in response to ergonovine may occur in patients with normal coronary arteries and atypical chest pain.

Adolescent↗
PubMed1983

Cardiovascular imaging with nuclear magnetic resonance.

This article provides some examples of what the previous article outlined. The sections on Image Display and Myocardial Characterization contain numerous illustrations of gating, cross-sectional images, flow signals, and ischemic injury. The possibility of metabolic imaging with NMR and quantitating blood flow is also considered.

Aorta, Abdominal↗
PubMed1983

Diagnostic test use in different practice settings. A controlled comparison.

Health maintenance organizations (HMOs) have lower than average medical care costs, but the reasons remain controversial. The diagnostic practices of cardiologists from an HMO, a university, and a community were therefore surveyed. First, cardiologists defined indications for coronary bypass surgery and then evaluated randomly selected case summaries of patients with chest pain. After review, the cardiologist rated the need for an exercise thallium scintiscan and for a coronary angiogram in each case. Community cardiologists had the broadest indications for bypass surgery. The HMO cardiologists chose thallium scintigraphy significantly less often than the other two types of cardiologists did. The HMO and university cardiologists both rated the need for coronary angiography significantly lower than did community cardiologists. Physicians in different practice settings therefore recommend costly diagnostic and therapeutic methods differently, even for identical patients.

Adult↗
PubMed1982

Phase image characterization of ventricular contraction in left and right bundle branch block.

The phase image is a computer-derived functional image, based on the analysis of the time versus radioactivity curve in each pixel location of the multiple gated blood pool scintigram. Within the ventricular regions of interest, the phase angle is roughly equivalent to the time of onset of counts reduction or to the time of onset of ventricular contraction and is expressed in degrees from 0 to 360 degrees. A gray scale-coded image of such a regional phase angle, the phase image, can be looked on as a map of sequential contraction. This method was applied in 33 patients without severe contraction abnormality including 16 patients with normal conduction, 9 with right bundle branch block and 8 with left bundle branch block. In patients with normal conduction the pattern of phase angle distribution, representing the pattern of ventricular contraction, was homogeneous and symmetric in both the left and right ventricles. Analysis in this normal group indicated a slight but significant difference between the mean (+/- standard deviation) phase angle of the left ventricle (8.5 +/- 11.8 degrees) and that of the right ventricle (13.6 +/0 12.9 degrees, p = 0.01). There was a slight, but nonsignificant difference between mean intrapatient left and right ventricular phase angle onset (1.9 +/- 6.5 degrees). The mean phase angle of the right ventricle in patients with right bundle branch block (27.6 +/- 14.2 degrees) and of the left ventricle in those with left bundle branch block (21.9 +/- 14.0 degrees) was delayed compared with that in patients with normal conduction (p less than 0.05 for both). The mean intrapatient difference between left and right ventricular mean phase angles in patients with normal conduction (-5.2 +/- 6.8 degrees) was significantly different from that in patients with right (-21.8 +/- 10.3 degrees, p less than 0.001) or left (21.8 +/- 6.8 degrees, p less than 0.001) bundle branch block. The mean intrapatient difference between onset of left and right ventricular phase angles was also significantly different from normal in patients with right (-10.6 +/- 7.5 degrees, p less than 0.005) or left (18.7 +/- 8.3 degrees, p = 0.01) bundle branch block. Although phase imaging is not without artifactual error, this study demonstrates that the phase image can characterize familiar conduction abnormalities. It presents the potential for application as a general noninvasive tool in the investigation of the timing and sequence of ventricular contraction in patients with normal or abnormal ventricular activation.

Adult↗
PubMed1982

An accurate means of detecting and characterizing abnormal patterns of ventricular activation by phase image analysis.

The ability of scintigraphic phase image analysis to characterize patterns of abnormal ventricular activation was investigated. The pattern of phase distribution and sequential phase changes over both right and left ventricular regions of interest were evaluated in 16 patients with normal electrical activation and wall motion and compared with those in 8 patients with an artificial pacemaker and 4 patients with sinus rhythm with the Wolff-Parkinson-White syndrome and delta waves. Normally, the site of earliest phase angle was seen at the base of the interventricular septum, with sequential change affecting the body of the septum and the cardiac apex and then spreading laterally to involve the body of both ventricles. The site of earliest phase angle was located at the apex of the right ventricle in seven patients with a right ventricular endocardial pacemaker and on the lateral left ventricular wall in one patient with a left ventricular epicardial pacemaker. In each case the site corresponded exactly to the position of the pacing electrode as seen on posteroanterior and left lateral chest X-ray films, and sequential phase changes spread from the initial focus to affect both ventricles. In each of the patients with the Wolff-Parkinson-White syndrome, the site of earliest ventricular phase angle was located, and it corresponded exactly to the site of the bypass tract as determined by endocardial mapping. In this way, four bypass pathways, two posterior left paraseptal, one left lateral and one right lateral, were correctly localized scintigraphically. On the basis of the sequence of mechanical contraction, phase image analysis provides an accurate noninvasive method of detecting abnormal foci of ventricular activation.

Adult↗
PubMed1982

The significance of nitroglycerin-induced changes in ventricular function after acute myocardial infarction.

The potential of nitroglycerin for improving global and regional ventricular function after acute myocardial infarction and predicting serial change in ventricular function at the time of hospital discharge was investigated. Equilibrium multiple gated blood pool scintigrams were performed at rest before and after sublingual administration of nitroglycerin in 18 patients an average of 36 hours after infarction and again at discharge. Global right and left ventricular function and regional left ventricular function of infarct and noninfarct zones were determined scintigraphically. In the early study nitroglycerin increased both mean (+/- standard deviation) left ventricular ejection fraction (0.51 +/- 0.15 to 0.55 +/- 0.15 ; p less than 0.02) and mean right ventricular ejection fraction (0.42 +/- 0.14 to 0.47 +/- 0.13; p less than 0.05). Left ventricular ejection fraction significantly increased in 5 of the 18 patients. It increased late in five of the six patient who exhibited an increase early after nitroglycerin but in only 2 of the 12 patients who did not exhibit an early increase (p less than 0.06). Regional ejection fraction in the infarct zone increased late in 7 of the 12 patients who exhibited an early increase after nitroglycerin and in none of the 6 who did not exhibit an early increase (p less than 0.05). Both right and left ventricular global ejection fraction and regional ejection fraction showed little late responsiveness to nitroglycerin. Early after infarction, sublingual nitroglycerin improved left, right and regional ejection fraction at the infarct site in some patients. These nitroglycerin-induced changes predicted those patients whose global ventricular function and regional left ventricular function at the infarct site improved late.

Administration, Oral↗
PubMed1982

The late prognostic value of acute scintigraphic measurement of myocardial infarction size.

Infarct, perfusion and blood pool scintigraphy were performed in 62 patients during hospitalization for acute myocardial infarction. The largest measured infarct or perfusion image defect and left ventricular ejection fraction were related to the late prognosis determined a mean of 16 months after the event. Breakpoint values for all scintigraphic variables could separate those who were asymptomatic on follow-up from those who died. The best indicators for selection of survivors and nonsurvivors were a scintigraphic infarct size greater than or equal to 25 cm2 and a perfusion abnormality greater than or equal to 35% of the projected left ventricular area. Among patients with perfusion abnormalities above this limit, 61% died; 93% of those with small perfusion abnormalities survived. Scintigraphic measurements of relative myocardial perfusion and function best separated patients asymptomatic on follow-up from those who developed heart failure and also best identified those with an unfavorable evolution, who developed heart failure or died. Early scintigraphic parameters appeared more accurate than other clinical laboratory indicators for determining late prognosis and could be important in planning treatment after acute infarction.

Aged↗
PubMed1982

Hemodynamic benefit of atrial pacing in right ventricular myocardial infarction.

Right ventricular and inferior-posterior myocardial infarctions in four patients were complicated by low-output syndrome unresponsive to increasing intravascular volume. Ventricular pacing was started because of bradyarrhythmias, but failed to increase cardiac output; atrial pacing at identical rates resulted in dramatic increases in cardiac output. The importance of atrial contribution to ventricular function, as well as the role of the pericardium in this clinical setting, are discussed. In treating right ventricular myocardial infarction, atrial or atrioventricular sequential cardiac pacing may be preferable to ventricular pacing.

Aged↗
PubMed1981

The inconsistent pattern of thallium defects: a clue to the false positive perfusion scintigram.

Exercise thallium myocardial scintigrams were analyzed in 76 consecutive patients with documented normal coronary arteries to identify the factors associated with abnormal or "false positive" studies. The thallium scintigrams had been judged normal in 60 patients (79 percent) and abnormal in 16 (21 percent). Analysis of the location of thallium defects in the 16 patients with abnormal scintigrams revealed a pattern that was consistent with coronary artery disease in 5, including 4 with an abnormal left ventricle, and a pattern that was inconsistent in the other 11. In 9 of these 11 patients the pattern of defects suggested soft tissue attenuation, by the diaphragm in 2 and breast or adipose tissue in 7, whereas in the other 2 patients isolated apical defects were seen. Among exercise myocardial scintigrams performed in 68 randomly selected patients with abnormal coronary arteries, 6 (9 percent) were reported to be normal. In four patients with abnormal scintigrams, the diagnosis of coronary artery disease was based on an inconsistent pattern. In three of these the pattern was related to isolated apical defects and in one it was related to apparent soft tissue attenuation. "Consistent" scintigraphic defects, seen frequently in patients with normal coronary arteries, in whom they are usually associated with an abnormal left ventricle. In patients with normal coronary arteries, "inconsistent" thallium defects are probably related to soft tissue attenuation or to normal apical thinning. Although defects caused by isolated apical abnormalities and soft tissue attenuation are also seen in patients with coronary diseases and add somewhat to scintigraphic sensitivity, they are a rare cause of diagnostic scintigraphic abnormalities in patients with coronary disease. The incidence of false positive thallium scintigrams could be reduced and overall accuracy improved by careful attention to the pattern of thallium defects.

Adult↗
PubMed1981

Detecting and localizing peripheral arterial disease: assessment of 201Tl scintigraphy.

Detection and localization of peripheral arterial disease was evaluated by intravenous injection of 201Tl at peak exercise in 22 subjects. Images of the gluteals (G), thighs (T), knees (K), and calves (C) were obtained at exercise and after a 3 hr delay, and stored in a computer, interextremity (T/T and C/C) and intraextremity (G/T, T/C, T/K) counts ratios were calculated. Normal values were defined in 11 control subjects and compared with those obtained in 11 patients with angiographically proven peripheral arterial disease. Bilateral disease was detected scintigraphically in all patients. T/T and G/T ratios correctly predicted proximal disease in nine of 12 limbs, while C/C, T/C, T/K ratios correctly predicted distal disease in 21 of 21 involved limbs. Delay images 3 hr after stress generally reverted towards the norm. Objective systematic evaluation of limb isotope uptake permits accurate detection and localization of peripheral arterial disease. Method accuracy compares favorably with physical signs and with other noninvasive methods of detection of peripheral vascular disease. Scintigraphy presents advantages which indicate great clinical potential.

Adult↗
PubMed1980

A consideration of factors affecting the diagnostic accuracy of thallium-201 myocarial perfusion scintigraphy in detecting coronary artery disease.

Several factors influence the ability of TI-201 myocardial perfusion scintigraphy to detect coronary artery disease. Among these are the physiologic effect of the coronary lesion on relative myocardial perfusion and radionuclide distribution; technical and physiologic aspects of the scintigraphic process; and observer interpretation. The diagnostic accuracy of this scintigraphic method is related to: (1) the extent of the hypoperfused myocardium, which will depend on the severity and extent of coronary disease, the presence of collaterals, the exercise method, and the timing of thallium administration and scintigraphy; (2) the scintigraphic process, which depends on the nature of the isotope, the imaging system, and the method of image display; and (3) image interpretation, which depends on the experience of the observer as well as on the area of hypoperfused myocardium and the scintigraphic process. The diagnostic accuracy of scintigraphy for detecting coronary disease can be optimized by computer methods of image enhancement, which maximize differences in image contrast; by electrocardiographic gating; and by emission computer tomography. Other computer methods have been developed to reduce or eliminate observer intervention in interpretation and to increase the objectivity of the method.

Coronary Disease↗
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↗