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Biomedical subjects

B Barzilai

Publications and source records attributed to B Barzilai.

At least 73 records · Page 4Linked to original sources
PubMed1991

Intraoperative ultrasonographic evaluation of the ascending aorta in 100 consecutive patients undergoing cardiac surgery.

Dislodgement of atheromatous plaque from the ascending aorta following manipulation is one of the principal causes of stroke following cardiac surgery. To define clinical correlates that predict the presence of severe atherosclerosis, we performed ultrasonographic evaluation of the ascending aorta at the time of cardiac surgery in 100 consecutive patients. The ascending aorta was divided into three equal segments for analysis, and the severity of atherosclerosis was determined as mild when intimal thickening (less than 3 mm) was localized to one segment, moderate when intimal thickening (greater than 3 mm) was present in one or two segments, and severe when intimal thickening (greater than 3 mm) was present throughout the entire circumference in all three segments. Thirty-eight percent of the studies were normal, mild atherosclerosis was present in 33%, moderate atherosclerosis in 19%, and severe atherosclerosis in 10% of the patients. Palpation of the ascending aorta to detect atherosclerosis significantly underestimated the presence (p less than 0.001) and severity (p less than 0.001) of atherosclerosis when compared with ultrasonography. Age, carotid artery disease, diabetes, gender, smoking, and hypertension were evaluated for their ability to discriminate between normal and severely atherosclerotic aortas. Stepwise logistic regression analysis showed age (p less than 0.02) and diabetes (p less than 0.04) to be significant independent predictors of the presence of severe atherosclerosis in the ascending aorta. Based on the ultrasonographic findings, the operative procedure was altered to reduce the risk of embolization in 17% of the patients. We conclude that high-resolution images of the ascending aorta for identification of atherosclerosis can be obtained by ultrasonography.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Saline contrast enhancement of tricuspid regurgitant jets detected by Doppler color flow imaging.

Contrast techniques have been used to improve detection of peak velocities by Doppler spectral analysis. To define the effect of contrast enhancement on the tricuspid regurgitation (TR) jet area and length, 29 patients were studied (25 transthoracic, 4 transesophageal) with 2-dimensional color flow imaging. Three- to 5-ml of agitated saline was injected and images were obtained from 4-chamber views at 12- or 16-cm depth setting. Color gain was optimized to display TR jet at baseline and then reduced to minimal settings before injection. Measurements of TR jet area and length were made in 3 to 5 consecutive cycles. A ratio of TR jet area to 2-dimensional area was derived. TR jet area at baseline was 4.7 +/- 3.6 cm2 and increased significantly (p less than 0.0001) in 26 patients to 8.1 +/- 6.3 cm2 after contrast enhancement. Jet length at baseline was 3.4 +/- 1.7 cm and increased significantly (p less than 0.0001) in 20 patients to 4.1 +/- 1.8 cm after contrast enhancement. The ratio of TR jet area to right atrial area also increased significantly (p less than 0.0001) to greater than 0.20 in 18 of 28 patients after enhancement. Increases in jet area and length were not associated with changes in TR jet or diastolic inflow velocities measured by continuous wave Doppler at baseline and after contrast. Thus, contrast enhancement increases the amplitude of Doppler signals responsible for transvalvular and regurgitant flow. By reducing the effect of attenuation and improving signal-to-noise ratio, it improves delineation of the TR jet using color flow imaging.

Adult↗
PubMed1990

Prognostic significance of mitral regurgitation in acute myocardial infarction. The MILIS Study Group.

To define the frequency, natural history and clinical correlates of the murmur of mitral regurgitation (MR) detected after myocardial infarction, clinical data from 849 patients with documented acute myocardial infarction were analyzed. A murmur suggestive of MR was present on admission in 76 patients (9%). Patients with MR on admission were older and more apt to be female and nonwhite. They also had a significantly greater frequency of prior infarction and signs and symptoms of congestive heart failure. There was no difference in the location (anterior or inferior) of infarction. Patients with MR on admission had a 36% mortality compared to 16% for those who developed MR later in the hospitalization and 15% for those without MR by auscultation (p less than 0.001). Correction for differences in baseline variables indicated that the presence of MR on admission did not contribute independently to mortality. Thus, the murmur of MR derives its prognostic significance from integration of multiple clinical, radiographic and electrocardiographic characteristics.

Female↗
PubMed1990

Congenital tricuspid valve stenosis with atrial septal defect and left anterior fascicular block.

Congenital tricuspid valve stenosis in the absence of other valvular abnormalities is rare. In this report we describe a patient with congenital tricuspid valve stenosis, ostium secundum atrial septal defect, and electrocardiographic left anterior fascicular block, who presented with paradoxical emboli. This case, as well as previous case reports, suggests that congenital tricuspid stenosis with ostium secundum atrial septal defect is associated with left anterior fascicular block.

Adult↗
PubMed1990

Myocardial ultrasonic backscatter for characterization of ischemia and reperfusion: relationship to wall motion.

We have previously shown that cardiac cycle-dependent variation of integrated backscatter occurs in normal myocardium. To determine whether myocardial ischemia and reperfusion can be distinguished by real-time integrated backscatter imaging we performed 10 min balloon occlusion of the Left Anterior Descending (LAD) coronary artery followed by reperfusion in 10 closed-chest anesthetized dogs. Images were obtained at baseline, during occlusion, and up to 120 min after reperfusion. We measured the magnitude and delay of cyclic variation of integrated backscatter in segments with and without asynergy. Radiolabeled microspheres were used to verify both ischemia and reperfusion. Ischemic segments exhibited decreased magnitude and increased normalized delay of cyclic variation of integrated backscatter (from 3.3 +/- 0.3 dB to 1.4 +/- 0.2 dB, mean +/- SE; and from 0.95 +/- 0.03 to 1.67 +/- 0.15, respectively, all p less than or equal to 0.001). Reperfusion promptly restored the magnitude of cyclic variation toward normal. However, the delay of the cyclic variation was restored only partially. Wall motion analysis of the ischemic sites revealed persistent abnormalities throughout the reperfusion interval despite return to normal of the magnitude and delay of cyclic variation. Thus, real-time integrated backscatter imaging permits detection and differentiation of changes in myocardial acoustic properties indicative of ischemia and of subsequent reperfusion.

Animals↗
PubMed1990

Hemodynamic importance of systolic ventricular interaction, augmented right atrial contractility and atrioventricular synchrony in acute right ventricular dysfunction.

To delineate the determinants of right ventricular performance with acute right ventricular dysfunction, surgical electrical isolation of the right ventricular free wall was produced in 13 dogs. During atrioventricular (AV) pacing, hemodynamic and wall motion measurements were normal. When not paced, the right ventricular free wall became asystolic, resulting in a depressed and bifid right ventricular systolic pressure (33 +/- 5 to 18 +/- 4 mm Hg) and decreased left ventricular systolic pressure (100 +/- 18 to 80 +/- 18 mm Hg) and stroke volume (14 +/- 4 to 10.3 +/- 3.5 ml) (all p less than 0.05). Ultrasound demonstrated right ventricular free wall dyskinesia, increased right ventricular end-diastolic size (155 +/- 13% of control), but decreased left ventricular size (69 +/- 11% of control) (both p less than 0.05). Right atrial pressure increased (5.8 +/- 2.5 to 7.6 +/- 2.8 mm Hg, p less than 0.05) with an augmented A wave and blunted Y descent, indicating pandiastolic right ventricular dysfunction. The septum demonstrated reversed curvature in diastole and bulged paradoxically into the right ventricle during early systole, generating the initial peak of right ventricular pressure and reducing its volume. Later, posterior septal motion coincided with maximal left ventricular pressure and the second peak of the right ventricular waveform. Left ventricular pacing alone led to further decreases in right ventricular systolic pressure and size, left ventricular systolic pressure and stroke volume. The previously augmented A wave was replaced by a prominent V wave. Therefore, when contractility of its free wall is acutely depressed, right ventricular performance is dependent on left ventricular-septal contractile contributions transmitted by the septum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Determinants of hemodynamic compromise with severe right ventricular infarction.

To elucidate determinants of hemodynamic compromise in patients with acute right ventricular (RV) infarction, we studied 16 patients with hemodynamically severe RV infarction by right heart catheterization and two-dimensional ultrasound. Severe RV systolic dysfunction, evident by ultrasound in all patients as RV dilatation and depressed RV free wall motion, was associated with a broad sluggish RV waveform, diminished peak RV systolic pressure (27.6 +/- 4.5 mm Hg), and depressed RV stroke work (4.6 +/- 2.4 g.m/m2). Paradoxical septal motion was consistently noted. In some cases, the septum bulged into the right ventricle in a pistonlike fashion and appeared to mediate systolic ventricular interaction through which left ventricular septal contraction contributed to RV pressure generation. RV diastolic dysfunction was indicated by elevated RV end-diastolic pressures (13.7 +/- 2.7 mm Hg), RV "dip and plateau," equalization of diastolic filling pressures, and reversal of diastolic septal curvature toward the volume-deprived left ventricle. A prominent right atrial (RA) X and blunted Y descent, indicative of impairment of RV filling throughout diastole, were confirmed in all patients by their relation to RV systolic events. Patients manifested one of two distinct RA waveform morphologies differentiated by A wave amplitude and associated with disparate clinical courses. In eight patients, an RA W pattern was evident, characterized by augmented A waves; eight others manifested an M pattern constituted by depressed A waves. Compared with those with an M pattern, patients with a W pattern had higher peak RV pressures (29.6 +/- 3.8 versus 25.5 +/- 4.3 mm Hg, p less than 0.05), better cardiac output (3.4 +/- 0.3 versus 2.9 +/- 0.7 l/min, p less than 0.05), more favorable response to volume and inotropes, and less frequently required emergency revascularization for refractory shock (none versus five for those with an M pattern). Patients with a W pattern were more severely compromised if atrioventricular dyssynchrony developed and were more dramatically improved by restoration of physiological rhythm. Angiography in patients with depressed A waves demonstrated more proximal coronary obstruction leading to ischemic compromise of RA function, whereas in those with augmented A waves, the culprit lesion was proximal to the RV but distal to the RA branches. These results indicate that hemodynamic compromise in patients with RV infarction is exacerbated by decreased preload reserve that is dependent on atrial systole. The amplitude of the RA A wave, an indication of the status of RA function, is an important determinant of RV performance and hemodynamic compromise.

Blood Pressure↗
PubMed1990

Characterization of regional diastolic pressure gradients in the right ventricle.

Regional intraventricular pressure gradients exist in the left ventricle (LV) during both the early and late filling phases of diastole. These regional pressure gradients comprise a fundamental component of the mechanism of normal LV filling. To determine whether similar diastolic pressure gradients also occur in the right ventricle (RV), we measured right atrial (RA) and RV regional pressures with use of micromanometers in six anesthetized, closed-chest dogs. Tricuspid flow velocity was recorded with use of transesophageal Doppler echocardiography, and right ventriculograms were obtained with contrast angiography. As in the LV, the maximum RA-RV pressure gradient during early diastole was consistently greater if RV pressure was measured near the apex than in the inflow tract (1.6 +/- 0.5 versus 0.8 +/- 0.4 mm Hg). The area of reversed pressure was also found to be significantly greater in the apex than in the inflow tract (72 +/- 43 versus 8 +/- 6 mm Hg.msec). However, unlike the LV, the lowest minimum pressure was usually recorded in the RV outflow tract, resulting in a significantly increased RA-RV outflow tract pressure gradient compared with the RA-RV apex pressure gradient (2.5 +/- 0.8 versus 1.6 +/- 0.5 mm Hg). Analysis of right ventriculograms indicates marked narrowing of the RV outflow tract at end systole in all six animals, suggesting that an end-systolic deformation in this region is the likely mechanism for production of low early diastolic pressure in this region. During atrial contraction the RV regional pressure gradient pattern was similar to the LV pattern: the RV a-wave ascent occurred earlier in the inflow tract and later in the apex. A-wave ascent appeared to occur almost simultaneously in the apex and outflow tract. In the six animals, Doppler-derived peak tricuspid flow velocity during early diastole was 35 +/- 6 cm/sec. Early tricuspid flow acceleration (393 +/- 101 cm/sec2) was found to be significantly greater than deceleration of flow (182 +/- 59 cm/sec2). Comparison of tricuspid pressure-flow data with mitral pressure-flow data previously obtained in our laboratory indicates that the driving pressure gradient across the tricuspid valve is significantly less than across the mitral. This pressure difference corresponds to differences in acceleration and peak flow found across the two valves. Consideration of these physiological patterns of RV diastolic intraventricular pressure and their relation to filling has important implications with regard to the development of indexes that characterize diastolic pressure-flow relations and provides physiological insight relating to the location of ventricular restoring forces.

Animals↗
PubMed1990

Predictors of employee involvement in a worksite health promotion program.

Although worksite health promotion programs have proliferated, little is known about the population they reach. This study of employees of a large utility company compared whether the same characteristics which predict recruitment also predict extended participation. The study also prospectively assessed how risk factors are related to employees' on-going extended participation. The findings demonstrate that sociodemographic predictors of recruitment are almost mirror images of the predictors of extended participation. Over time employees who are at higher risk for cardiovascular disease participated in on-going sessions less frequently. Data suggest that referral to targeted sessions does not result in higher rates of attendance by employees with a particular risk factor, although there is no evidence of selective avoidance. Organizational influences on participation evident from the beginning are sustained through four sessions. Programs targeting higher risk employees nested within worksite-wide programs may be useful to increase the extended participation of individuals at elevated risk for heart disease.

Adult↗
PubMed1989

Intravascular thrombosis: definitive detection by quantitative tissue characterization in vitro.

To improve the sensitivity and reliability of the ultrasonic detection of intravascular thrombosis, we employed quantitative ultrasonic techniques for the analysis of thrombi induced in vitro. Citrated human blood or platelet-rich plasma was added to sections of canine thoracic aorta mounted vertically in a saline bath. CaCl2 and thrombin were then added to induce thrombosis. Ultrasonic integrated backscatter measured sequentially with a 10-MHz focused transducer exhibited more than a 10 dB increase in integrated backscatter when either whole blood or platelet-rich plasma was clotted (-61.7 dB to -47.4 dB whole blood; less than -70 dB to -52.8 dB platelet-rich plasma). Thus, large significant changes in integrated backscatter measured from structures within the arterial lumen were readily detectable and indicative of thrombosis in situ.

Adult↗
PubMed1989

Ultrasound integrated backscatter tissue characterization of remote myocardial infarction in human subjects.

To determine whether quantitative ultrasound tissue characterization differentiates normal myocardial regions from segments of remote infarction, 32 consecutive patients with a diagnosis of previous myocardial infarction were evaluated. Images were obtained in real time with a modified two-dimensional ultrasound system capable of providing continuous signals in proportion to the logarithm of integrated backscatter along each A line. In 15 patients, adequate parasternal long-axis images that delineated both normal and infarct segments were obtained with standard time-gain compensation. Image data were analyzed to yield both magnitude and delay (electrocardiographic R wave to nadir normalized for the QT interval) of the cyclic variation of backscatter. Cyclic variation was present in 55 of 56 normal myocardial sites, averaging (mean +/- SEM) 3.2 +/- 0.2 dB in magnitude and exhibiting a mean normalized delay of 0.87 +/- 0.03. The magnitude of cyclic variation in infarct segments was significantly reduced to 1.1 +/- 0.2 dB (42 sites), and the delay was markedly increased to 1.47 +/- 0.12 (21 sites) (p less than 0.0001 for both). In 20 of 42 infarct sites, no cyclic variation was detectable. Thus, ultrasound tissue characterization quantitatively differentiated infarct segments from normal myocardium in patients with remote myocardial infarction.

Adult↗
PubMed1989

Intraoperative ultrasonic imaging of the ascending aorta.

Embolization of atherosclerotic material from the ascending aorta resulting from placement of cannulas or vascular clamps is a major cause of stroke during cardiac surgical procedures. In an effort to identify atherosclerotic disease of the ascending aorta which might predispose to embolization, intraoperative B-mode ultrasonography was performed in 50 patients. The aorta was imaged from the aortic annulus to the origin of the innominate artery in transverse and longitudinal views. The results were compared with visual and tactile examination of the aorta for the presence of atherosclerosis. Ultrasonic imaging demonstrated atherosclerotic disease in 29 patients (58%). Visual examination and palpation identified atherosclerosis in 12 patients (24%). The amount and location of plaque was sufficient to require a change in the site of arterial cannulation or the proximal vein graft anastomoses or the technique of cardiopulmonary perfusion in 12 of the 50 patients (24%). All 12 patients were 65 years of age or older. Palpation underestimates the presence of atherosclerotic disease in the ascending aorta. Intraoperative ultrasonography accurately identifies patients with atherosclerotic disease of the ascending aorta. This allows the surgeon to modify cannulation, perfusion, and operative techniques to reduce the risk of perioperative stroke due to the embolization of atherosclerotic debris from the ascending aorta.

Aged↗
PubMed1989

Automated determination of the magnitude and time delay ("phase") of the cardiac cycle dependent variation of myocardial ultrasonic integrated backscatter.

An algorithm for quantitative description of cardiac cycle dependent variation of integrated backscatter (cyclic variation) has been developed and is shown to be suitable for analysis of nonsinusoidal data typical of ultrasonic tissue characterization measurements from myocardium in vivo. The algorithm produces estimates of the magnitude of variation and of the time delay relative to the electrocardiographically recorded QRS-complex. To validate the algorithm, 246 integrated backscatter measurements were analyzed both manually and by the automated method. The magnitude and time delay estimates from the two methods correlated closely. With a separate set of data, the algorithm produced reasonable descriptions of the cyclic variation for 89 of 101 integrated backscatter measurements. Only modest computational power is required for effective implementation of this algorithm, facilitating inclusion of online automated analysis capabilities in quantitative ultrasonic tissue characterization systems.

Algorithms↗
PubMed1989

Avoidance of embolic complications by ultrasonic characterization of the ascending aorta.

Surgical manipulation of the atherosclerotic ascending aorta in elderly patients is often accompanied by serious complications. To reduce the risk of disrupting highly degenerated but nonpalpable plaques, we used quantitative ultrasonic techniques to intraoperatively image the ascending aorta in 33 patients (mean age, 71 years) as a guide to selection of cross-clamping or cannulation sites. Two-dimensional, integrated backscatter images (integration time, 1.6 mu sec) were obtained with a 5-MHz transducer wrapped in a sterile sheath and placed directly on the aorta. Significant atherosclerotic disease was detected in 18 patients. Calcified lesions were found in 13 patients, and fibrofatty lesions were found in five. In four patients undergoing repair of degenerative aneurysms, the extent and distribution of ultrasonically delineated regions of calcification and fibrosis were confirmed histologically. In eight (24%) patients, the composition, severity, and location of plaques delineated ultrasonically led to selection of alternate cannulation sites without resultant atheroembolism. Thus, ultrasonic tissue characterization sensitively delineates the extent of aortic atherosclerosis, and its use may decrease the risk of atheroembolism.

Aged↗
PubMed1988

Significance of Doppler-detected mitral regurgitation in acute myocardial infarction.

To define the incidence of mitral regurgitation (MR) and elucidate its potential contribution to the development of severe congestive heart failure after acute myocardial infarction (AMI), Doppler echocardiograms were obtained within 48 hours of onset of AMI in 59 patients. The presence of MR was determined from the apical 4-chamber and parasternal long-axis views with pulsed Doppler. MR was detected in 23 of the 59 patients (39%) and was similarly frequent in patients with anterior (11 of 24 or 46%) and inferior AMI (12 of 34 or 35%). Patients with MR were older (71 +/- 3 vs 62 +/- 2 years, p less than 0.005), had a higher incidence of prior AMI (8 of 23 vs 4 of 36, p less than 0.05) and larger end-diastolic volume indexes by radionuclide ventriculography (112 +/- 9 vs 72 +/- 4, p less than 0.005). A systolic murmur was heard in only 10 of 23 patients with MR detected by Doppler. Mortality determined 8 to 14 months after the index AMI was 48% (11 of 23) in patients with MR but only 11% (4 of 30) in those without it (p less than 0.01). Thus, this study determined that clinically silent MR frequently complicates AMI and its presence is associated with and is a potential determinant of severe congestive heart failure and mortality.

Aged↗
PubMed1988

Relationship of QRS scoring system to enzymatic and pathologic infarct size: the role of infarct location.

A method for estimating infarct size from 12-lead ECGs has been developed but not extensively validated. To assess its accuracy, ECG scores from 62 patients admitted to the coronary care unit at Barnes Hospital were compared to infarct size calculated from plasma MB creatine kinase (MB-CK) activity. A second cohort of 29 patients enrolled in the Multicenter Investigation of the Limitation of Infarct Size (MILIS) was evaluated as a test set and to provide pathologic correlates. Patients with conduction system disease, ventricular hypertrophy, or multiple infarctions were excluded, as were those in the Barnes group who had undergone thrombolytic therapy. ECGs obtained early (days 3 to 7 in the Barnes group and day 3 in the MILIS group) or late (days 8 to 14 in the Barnes group) were scored manually and by computer. QRS scores from early ECGs of patients with anterior infarctions correlated closely with MB-CK estimates of infarct size (r = 0.71 [Barnes] and 0.85 [MILIS] and with anatomic data (r = 0.78). Enzymatic and pathologic infarct size also correlated well (r = 0.85). Correcting for body surface area by means of total CK-derived infarct size or use of QRS scores from late ECGs did not alter the correlation coefficients. Among patients with inferior infarctions QRS scores corresponded poorly with MB-CK infarct size (r = 0.28 [Barnes] and r = -0.42 [MILIS]) and pathologic infarct size (r = -0.20), despite a significant relationship between pathologic and MB-CK estimates (r = 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The transmitral pressure-flow velocity relation. Effect of abrupt preload reduction.

Although recent animal and clinical studies suggest that Doppler-derived indexes may be useful for the characterization of ventricular diastolic behavior, the hemodynamic basis for the preload dependency of these indexes has not previously been fully elucidated. Accordingly, effects of reduction of left atrial load on the pressure-flow velocity relation were characterized in 10 anesthetized, closed-chest dogs during transient inferior vena caval occlusion by means of simultaneously recorded left atrial and left ventricular micromanometric pressure measurement and transesophageal Doppler echocardiograms. Within four or five beats after inferior vena caval balloon occlusion, left atrial loading was reduced as evidenced by a decrease in the slope of the left atrial v wave from 21 +/- 4 to 13 +/- 4 mm Hg/sec (p less than 0.001) and by a decrease in the first crossover point of left atrial and left ventricular pressures from 5.6 +/- 1.1 to 2.9 +/- 1.5 mm Hg (p less than 0.001). This decrease in left atrial loading resulted in reductions during early diastole of minimum left ventricular pressure (from 1.0 +/- 0.8 to -0.4 +/- 1.2 mm Hg, p less than 0.001), the maximum early forward (i.e., left atrial pressure greater than left ventricular pressure) transmitral pressure gradient (from 2.8 +/- 0.8 to 2.4 +/- 0.5 mm Hg, p less than 0.01); the slope of the rapid filling pressure wave (from 44 +/- 11 to 38 +/- 10 mm Hg/sec, p less than 0.025); and the area of the reversed (i.e., left ventricular pressure greater than left atrial pressure) transmitral pressure gradient (from 79 +/- 42 to 53 +/- 33 mm Hg.msec, p less than 0.05). During late diastole, both the heights and slopes of the left atrial and left ventricular a waves fell, resulting in a decrease in the maximum late transmitral pressure gradient (from 1.2 +/- 0.7 to 0.9 +/- 0.5 mm Hg, p less than 0.05). Vena caval occlusion also altered Doppler transmitral velocity profiles during both the early and late phases of diastole. Peak velocity of the E wave decreased (from 50 +/- 11 to 41 +/- 7 cm/sec, p less than 0.01) as did acceleration (from 880 +/- 222 to 757 +/- 258 cm/sec2, p less than 0.025) and deceleration (from 597 +/- 260 to 429 +/- 197 cm/sec2, p less than 0.025). Peak velocity of the A wave also fell (from 29 +/- 9 to 22 +/- 5 cm/sec, p less than 0.005). Abrupt inferior vena caval occlusion did not significantly change heart rate or mean aortic pressure.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗