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E H Botvinick

Publications and source records attributed to E H Botvinick.

At least 73 records · Page 4Linked to original sources
PubMed1987

Advances in noninvasive cardiovascular imaging: implications for the anesthesiologist.

We have presented a review of recent advances in medical imaging which are relevant to the practice of anesthesia and associated research. The appropriate interpretation and use of the information derived from these noninvasive technologies can prevent unnecessary morbidity and mortality. Echocardiography remains the most advanced tool for noninvasive cardiac imaging because of its applicability for most cardiac disorders and its exquisite spatial resolution. Two-dimensional systems produce real time, dynamic, qualitative assessments of cardiac chamber morphology, size, thickness, and performance. The development of transesophageal echocardiography has brought this imaging power into the operating room for use by anesthesiologists. Recently developed quantitative and color-coded Doppler techniques will reveal intracardiac flow patterns and their alterations by anesthetics and surgery. These advantages are partially offset by inherent difficulties in quantifying echocardiographic data, and the need for highly trained operators for image reproduction. Nuclear cardiology and echocardiology are highly complementary. The scintigraphic methods identify myocardium at risk for infarction, confirm infarction when present, and produce quantitative, highly reproducible estimates of ventricular filling and performance. Time required to obtain data can be very brief for first-pass techniques, and these data are ideally suited for computer processing. Equilibrium studies require a larger dose of radioactive material, but provide excellent assessment of segmental wall motion. Preoperative studies with dipyridamole and Tl can indicate the patients truly at high risk for perioperative myocardial infarction. Monitoring and intensive care efforts may be better allocated with this information. No new technology in the past decade has stirred as much interest among clinicians as magnetic resonance imaging. Like echocardiography, it uses no ionizing radiation and is entirely noninvasive. But, unlike other imaging techniques, it utilizes multiple tissue characteristics to provide quick, highly resolved, tomographic images. Since bone is invisible to the magnetic resonance scanner, tissues inside bony structures are often best revealed with MRI. Nonimaging studies, i.e., spectroscopic data not spatially encoded, may prove to be the most important research currently underway in this field. In vivo estimates of intracellular functions, enzyme kinetics, and drug kinetics and metabolism are already in progress. The effects of anesthetic in the central nervous system and other organs may be explored in ways previously not possible.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesiology↗
PubMed1987

Factors influencing myocardial response to metabolic acidosis in isolated rat hearts.

We assessed the effects of metabolic acidosis in Langendorff rat hearts to identify factors influencing myocardial response to metabolic acidosis. Intracellular pH (pHi), beta-ATP, phosphocreatine, and inorganic phosphate (Pi) content were measured by 31P nuclear magnetic resonance spectroscopy along with simultaneous measurements of coronary flow and developed pressure during 30 min of perfusion at pH = 6.8, followed by 15 min of reequilibration at pH = 7.4. Under high work-load conditions, pHi, high-energy phosphates, coronary flow, and developed pressure were severely reduced during metabolic acidosis. Each of these hearts exhibited a progressive decline in developed pressure and stopped beating during reequilibration. Lowering work load prevented severe biochemical or mechanical deterioration, allowing complete recovery during reequilibration. In the presence of high work load, factors found to improve myocardial tolerance to metabolic acidosis included maintaining base-line or higher levels of coronary flow with vasodilators or substitution of pyruvate for glucose as the energy-producing substrate. Raising perfusate osmolality did not prevent severe decreases in coronary flow and developed pressure during acidosis, but did allow a dramatic recovery during reequilibration. Recovery of biochemical and mechanical performance after 30 min of metabolic acidosis was directly related to 1) ln[ATP]/[ADP]f[Pi] greater than or equal to 4.1, where [ADP]f is the concentration of free ADP; 2) pHi greater than 6.40; and 3) ATP level greater than or equal to 75% of control.

Acidosis↗
PubMed1986

Left ventricular dimensions and mechanics in distance runners.

We assessed heart size and mechanics at rest in highly trained distance runners. By means of two-dimensional echocardiography, we compared 62 runners (greater than 40 miles/week) and 84 nonrunners. Left ventricular end-diastolic volume index and mass index were larger in runners than in nonrunners (p less than 0.001) and in men than in women (p less than 0.001). However, left ventricular end-diastolic and end-systolic volume/mass ratios were similar for runners and nonrunners. Noninvasive estimates of end-systolic and peak-systolic meridional and circumferential wall stresses were lower in runners than in nonrunners (p less than 0.001). Lower wall stress resulted from lower myocardial area/cavity area ratios, and thus 'average' radius/thickness ratios (measured from the parasternal short-axis view), in runners than in nonrunners (p less than 0.001). We detected a subtle change in ventricular shape among the distance runners. Basilar hypertrophy accounted for increased myocardial thickness with normal cavity size in the parasternal short-axis view, as might be expected in hearts working under sustained pressure elevations during prolonged training periods. However, cavity length and therefore ventricular volume were increased in the apical views, leading to a normal overall volume/mass ratio. These hearts have thus adjusted to periods of volume, as well as to pressure overload. Race performance is determined by a complex interaction between the heart, vascular, and skeletal muscle systems. In this study no parameter of myocardial size or function predicted 10 km or marathon race times, just as no physical characteristic or training record predicted left ventricular mass, end-diastolic or end-systolic volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Poor correlation between pulmonary arterial wedge pressure and left ventricular end-diastolic volume after coronary artery bypass graft surgery.

The authors studied 12 surgical patients in the intensive care unit post coronary artery bypass graft surgery and ten nonsurgical patients in the coronary care unit with chronic heart failure to determine the usefulness of the pulmonary arterial wedge pressure as an indicator of left ventricular preload. Left ventricular end diastolic volume was derived from concomitant determination of ejection fraction (gated blood pool scintigraphy) and stroke volume (determined from thermodilution cardiac output). In the nonsurgical patients, there was a significant correlation between changes in pulmonary arterial wedge pressure and left ventricular end-diastolic volume (P less than 0.05, r = 0.57). In the 12 patients studied during the first few hours after surgery, there was a poor correlation between changes in pulmonary wedge pressure (range = 4-32 mmHg) and left ventricular end-diastolic volume (range = 25-119 ml/m2), and a poor correlation between pulmonary arterial wedge pressures and stroke work index. In contrast, there was a good correlation between left ventricular end-diastolic volume and stroke work index. The poor correlation between the pulmonary arterial wedge pressure and left ventricular end-diastolic volume was not explained by changes in systemic or pulmonary vascular resistance. The altered ventricular pressure-volume relationship may reflect acute changes in ventricular compliance in the first few hours following coronary artery bypass graft surgery. While measurement of pulmonary arterial wedge pressure remains valuable in clinical management to avoid pulmonary edema, it cannot reliably be used as an index of left ventricular preload while attempting to optimize stroke volume in patients immediately following coronary artery bypass graft surgery.

Aged↗
PubMed1986

Quantitation of mitral regurgitation by Doppler echocardiography.

The evaluation and care of patients with mitral regurgitation would be facilitated by an easy, reproducible and noninvasive method that could quantitate the hemodynamic burden. In this study, we describe a new Doppler echocardiographic method that measures the regurgitant fraction and we compare it with angiographic and scintigraphic methods. A total of 27 patients with mitral regurgitation were evaluated by echocardiography and either cardiac catheterization or scintigraphy. With two-dimensional echocardiography, diastolic and systolic volumes were measured to derive the left ventricular stroke volume (LVSV). The forward stroke volume (FSV) was obtained from the product of M mode-derived aortic valve area and ascending aortic flow velocity integral assessed by continuous-wave Doppler. Regurgitant fraction was calculated as follows: (LVSV - FSV)/LVSV. Comparisons showed that regurgitant fraction calculated by Doppler echocardiography correlated with regurgitant fraction determined by both cardiac catheterization (r = .82) and by scintigraphy (r = .89). There was, however, an important interobserver variability within each method: 10%, 13%, and 11% for Doppler echocardiography, angiography, and scintigraphy, respectively. In conclusion, Doppler echocardiography can be used to quantitate mitral regurgitation. Serial noninvasive determinations of regurgitant fraction may be useful in the evaluation of therapy and in the follow-up of patients with mitral insufficiency.

Adult↗
PubMed1985

Undrained bloody pericardial effusion in the early postoperative period after coronary bypass surgery: a prospective blood pool study.

To assess the clinical importance of hemopericardium after cardiac surgery, serial blood pool scintigrams were performed in 13 random patients throughout the initial hours after coronary artery bypass graft surgery. Scintigraphic measurements of pericardial fluid accumulation and left ventricular ejection fraction were made. Hemodynamics, cardiac, output, and chest tube drainage were monitored; and symptoms of postpericardiotomy syndrome were recorded for a mean of 7.4 months after surgery. Seven of the 13 patients had no scintigraphic evidence of bloody pericardial effusion. Six patients had scintigraphic evidence of bloody pericardial effusion; three of these effusions were small, localized posteriorly, and evident throughout the study. In two other patients large collections of fluid (over 100 ml) developed. In one of these patients increased mediastinal drainage required reoperation. The other patient remained stable although mediastinal drainage decreased. The sixth patient showed a moderate effusion (95 ml) that decreased without evident effusion or drainage when the last image was taken. Two patients (one with evidence of a postoperative bloody effusion), had symptoms of postpericardiotomy syndrome in the follow-up period. This study reports the generally benign occurrence of bloody postoperative mediastinal effusions, the frequent accumulation of substantial amounts of undrained sanguineous fluid, and the lack of connection between the presence and or amount of pericardial blood and the postpericardiotomy syndrome. The importance of these scintigraphic findings can be interpreted only with knowledge of associated mediastinal drainage.

Aged↗
PubMed1985

ECG-synchronized cardiac MR imaging: method and evaluation.

An electrocardiographic (ECG) sensing and gating device compatible with a 0.35-tesla (T) magnetic resonance (MR) imager has been developed and used to produce 802 MR images of the heart in 30 patients. The instrument consists of an isolated acquisition module, an electrically floating preamplifier, and a monitor gating module. Two spin-echo images were acquired for each of five, 0.7-cm thick, transaxial sections from the base to the apex of the heart during each ECG-synchronized imaging run. Image quality was assessed in a blind study by two investigators, on a scale from 0 to 3, as diagnostic [2-3] or nondiagnostic [0-1]. There was agreement in 91.4% of their assessments of diagnostic images (68.1% of the images studied). Resolution of heart anatomy on the MR images was adversely affected by prolonged spin-echo time delay, imaging in late diastole, image acquisition at the cardiac apex, irregular triggering, and artifacts. The synchronization of gradient pulses to the ECG at 0.35 T appears safe for patients, permits diagnostic resolution of images, allows image acquisition at distinct points during the cardiac cycle, and enables monitoring of patients during imaging.

Adult↗
PubMed1985

The effects of coronary angioplasty and reperfusion on distribution of myocardial flow.

To assess the effects of angioplasty (PTCA) and intracoronary streptokinase (ICSK) on relative myocardial perfusion, we administered 99mTc-macroaggregated albumin (MAA) to the uninvolved coronary artery before successful PTCA in 33 patients and before successful infusion of ICSK in eight patients and of 111In-MAA into the same vessel after the intervention. In 10 patients who underwent PTCA, MAA was injected into the involved, instrumented coronary artery. Computer-processed images were acquired in registry and compared. Similar scintigraphic studies were performed in six control patients and in 11 in whom planned interventions were not performed or were unsuccessful. Distribution of MAA was also compared with angiographic results and with the distribution of 201Tl on images obtained in patients at rest or on redistribution images obtained before and soon after intervention in 22 patients. In control patients and those studied after aborted or unsuccessful intervention, scintigraphic results showed excellent correlation with the angiographic anatomy and were without serial change. When MAA was injected into the uninvolved vessel, the scintigram revealed evidence of collateral perfusion with retraction of the perfusion zone from that of the involved coronary in 19 of 33 patients undergoing PTCA and in three of eight of those receiving ICSK. When MAA was injected into the involved artery, a relative increase in perfusion was seen in eight of 10 patients after PTCA. Although 30 patients demonstrated scintigraphic evidence of collateral vessels, only 10 patients had angiographic evidence of collateral circulation before intervention. The distribution of 201Tl demonstrated little change in its global pattern and regions previously supplied by collaterals were generally well perfused after intervention. Coronary collateral perfusion may be inapparent angiographically and regress rapidly after angioplasty or reperfusion. Native perfusion is generally and quickly restored after successful PTCA or ICSK infusion, which obviates the need for collaterals. After intervention, the distribution of total perfusion may not change, but its regional source may demonstrate beneficial alterations, shifting from collateral to native circulation.

Angioplasty, Balloon↗
PubMed1985

[Imaging of the heart using nuclear magnetic resonance tomography. I: Tomography].

Magnetic resonance (MR) is a new concept in the diagnostics of the cardiovascular system. The basic principle of MR is nuclear magnetism. MR tomography is based on induction and spatial encoding of a nuclear magnetic resonance signal. Due to the high tissue concentration and MR sensitivity, medical MR imaging chiefly uses protons of water, 1H. MR tomography of protons presents highly contrasted images of soft tissue organs with spatial resolution in millimeters. Parametric analysis of the MR signal enables quantitative assessments of physico-chemical tissue properties, blood flow and perfusion. The method is noninvasive and without serious biological side effects. Ionising radiation or traditional contrast agents are not utilized. Using conventional ECG synchronized MR tomography the cardiac and great vessels anatomy are superbly resolved, exceptions being the resolution of coronary vasculature and cardiac valve apparatus. The excellent spatial resolution and flexible spatial image orientation are important advantages of quantitative assessment of cardiac function by MR imaging. Preliminary studies demonstrated clinical utility of tomographic assessments of T1 and T2 relaxation parameters as well as phase angle analysis for definition of myocardial ischemia, blood flow rates and wall motion dynamics. The first comparative studies between imaging modalities in diagnostics of specific cardiac disorders point to a superior anatomic resolution of the heart and vascular morphology by MR tomography. The utilization of MR tomography in cardiovascular medicine is new and it would be premature to assign a definite value to this costly technique in clinical evaluations of patients with heart disease. However, there is unequivocal evidence that MR technology will play a decisive role in cardiology in the future, and MR imaging already represents significant progress in the evaluation of patients with cardiac disease.

Aortic Diseases↗
PubMed1984

Value of noninvasive assessment of patients with atypical chest pain and suspected coronary spasm using ergonovine infusion and thallium-201 scintigraphy.

Twenty-six patients with known benign coronary anatomic characteristics and atypical chest pain syndromes were evaluated for the possibility of coronary spasm. Incremental intravenous ergonovine maleate infusions were administered, and thallium-201 scintigraphy was performed at the peak dosage and during recovery in the coronary care unit. With ergonovine therapy, 4 patients (16%) had chest pain associated with electrocardiographic (ECG) or scintigraphic changes. Nine patients (35%) had chest pain without associated ECG or scintigraphic changes, and 13 patients did not have chest pain in response to ergonovine administration, although 2 (8%) had ergonovine-induced scintigraphic defects. All 4 patients with ergonovine-induced chest pain and associated ECG or scintigraphic abnormalities had resolution or reduction of chest pain after medical treatment. However, 7 of the 9 patients with ergonovine-induced chest pain in the absence of ECG or scintigraphic abnormalities continued to have symptoms despite medical treatment a mean of 18 months later. In this limited study of a select group, bedside ergonovine provocation appeared safe. Many patients had chest pain, but few showed ECG or scintigraphic evidence of ischemia. Perfusion scintigraphy appears to have potential complementary value for the identification of an ischemic cardiac cause of atypical chest pain and provides a rationale for appropriate therapy.

Adolescent↗
PubMed1984

Mechanisms of improved left ventricular function following intravenous MDL 17,043 in patients with severe chronic heart failure.

To evaluate the mechanisms for improved left ventricular function with MDL 17,043 in patients with severe chronic heart failure, 24 patients were evaluated by simultaneous determination of hemodynamics by right heart catheterization and ejection fraction by computerized nuclear probe before and following intravenous administration of MDL 17,043 (mean cumulative dose 3.6 mg/kg). Following MDL 17,043, there was an increase in cardiac index (+62%), stroke volume index (+42%), and stroke work index (+68%), together with a decrease in pulmonary capillary wedge pressure (-46%), indicating improved left ventricular pump function. There was a marked reduction in systemic vascular resistance (-40%) and a modest reduction in arterial pressure, indicating decreased left ventricular outflow resistance. The ratio of peak systolic blood pressure to calculated left ventricular end-systolic volume tended to increase, but the change was not statistically significant. Despite a marked increment in stroke volume index, left ventricular ejection time corrected for heart rate was shortened, suggesting enhanced contractility. In the group as a whole, the calculated left ventricular end-diastolic volume remained unchanged, but it increased in 14 patients. Since pulmonary capillary wedge pressure fell in each patient, this suggests improved overall left ventricular distensibility. Thus, decreased left ventricular outflow resistance, and possibly increased contractile function, and improved left ventricular diastolic compliance may all contribute to improved left ventricular pump function with MDL 17,043 in patients with severe heart failure.

Aged↗
PubMed1984

Improved regional ventricular function after successful surgical revascularization.

Left ventricular segments with reversible asynergy at rest demonstrate reversible myocardial perfusion defects on exercise thallium-201 scintigrams. To determine if improved perfusion eliminates asynergy at rest, 23 patients with angina (stable in 21, unstable in 2) were studied before and after coronary artery bypass surgery. All patients underwent exercise myocardial perfusion scintigraphy, contrast ventriculography and coronary arteriography before and after surgery. Selective graft angiography was performed during the postoperative catheterization to determine graft patency. Segmental ventricular function was quantitated by a regional fraction method. The scintigrams were divided into five regions and compared with the corresponding regions of the ventriculogram. Seventy-one of a possible 142 ventricular segments exhibited exercise-induced perfusion deficits. Preoperative regional ejection fraction was normal in 42 of these segments and abnormal in 29. Postoperatively, in 19 of the abnormal segments, function improved or normalized. All these segments had improved perfusion during exercise after surgery and were supplied by a patent bypass graft. Nine of the 10 segments in which abnormal wall motion persisted postoperatively continued to have exercise-induced perfusion deficits, and 9 of the 10 segments were supplied by an occluded or stenotic graft or one with poor run off. Of the 42 segments with normal wall motion preoperatively, 30 had improved perfusion after surgery and 35 maintained normal function. This study indicates that asynergy at rest is permanently reversed after coronary bypass surgery if improved myocardial perfusion can be documented. These findings are consistent with but do not prove the concept that reversible rest asynergy may reflect chronic ischemia or a prolonged effect from previous ischemic episodes.

Angina Pectoris↗