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Biomedical subjects

B Barzilai

Publications and source records attributed to B Barzilai.

At least 37 records · Page 2Linked to original sources
PubMed1995

Transesophageal echocardiography and adult cardiac operations.

Transesophageal echocardiography (TEE) now is used widely as a monitoring technique during and after cardiac operations. Widespread adoption of the technique has provided a wealth of new information. This review analyzes the influence of TEE on the routine conduct of cardiac operations and on surgical decision making in specific areas. Its use in routine hemodynamic monitoring and problem solving, both intraoperatively and postoperatively, is discussed. Transesophageal echocardiography has a particular role in valve operations, in guiding and assessing the immediate results of mitral valve repair. It also has found application in the grading and operative management of the severely atheromatous aorta, the diagnosis and management of aortic dissection, and other aspects of surgery of the thoracic aorta. In addition, management in specialized areas, such as cardiopulmonary transplantation and the insertion and monitoring of ventricular assist devices, have also been helped by the information provided by TEE.

Adult↗
PubMed1995

Right ventricular dysfunction in low output syndrome after cardiac operations: assessment by transesophageal echocardiography.

BACKGROUND: Low output syndrome after cardiac operations is associated with high morbidity and mortality rates. The contribution of right ventricular dysfunction to this syndrome has not been fully characterized. The purpose of this study was to evaluate the utility of transesophageal echocardiography to identify the frequency and the in-hospital mortality from right ventricular dysfunction in patients with this syndrome. METHODS: Seventy-five consecutive patients undergoing transesophageal echocardiography for low output syndrome early after cardiac operations were evaluated. The findings from transesophageal echocardiography were correlated with the type of surgical procedure, cross-clamp time, right heart hemodynamics, and coronary angiography. RESULTS: Right ventricular systolic dysfunction occurred in 36 patients (42%); in 17 patients it was isolated and in 19 patients it occurred in combination with left ventricular dysfunction. Postoperative right ventricular dysfunction was not uniformly associated with important right coronary artery disease or with prolonged ischemic time during cardiopulmonary bypass. Hemodynamic data were not useful to distinguish the group with postoperative right ventricular dysfunction. Patients with right ventricular dysfunction had a high (44%) in-hospital mortality rate. CONCLUSIONS: Right ventricular dysfunction occurs frequently in patients with low output syndrome after cardiac operations and is associated with a high in-hospital mortality rate. Better understanding of the mechanisms causing postoperative right ventricular dysfunction may provide insight for preventing this complication.

Adult↗
PubMed1995

Multiplane transesophageal echocardiographic doppler imaging accurately determines cardiac output measurements in critically ill patients.

OBJECTIVES: To compare cardiac output and stroke volume measured by multiplane transesophageal Doppler echocardiography with that measured by the thermodilution technique. DESIGN: Prospective direct comparison of paired measurements by both techniques in each patient. SETTING: Cardiac surgery and myocardial infarction intensive care units. PATIENTS: Twenty-nine patients, mean age (+/- SD) 67 +/- 8 years. Nineteen had undergone open heart surgery and 10 had suffered acute myocardial infarction. METHODS: Cardiac output and stroke volume were measured simultaneously by the thermodilution technique and multiplane transesophageal Doppler echocardiography via the transgastric view (119 +/- 8 degrees) with the sample volume positioned at the level of the left ventricular outflow tract. RESULTS: Stroke volume and cardiac output measurements were obtained in 29 of 33 patients (88%). Mean values were 50 +/- 13 mL and 4.8 +/- 1.3 L/min by Doppler and 51 +/- 14 mL and 4.9 +/- 1.4 L/min by thermodilution (r = 0.90, r = 0.91, p < 0.001). The mean differences in values obtained with the two techniques were 1 +/- 6 mL (2 +/- 12%) and 0.1 +/- 0.7 L/min (2 +/- 12%). CONCLUSIONS: Multiplane transesophageal echocardiography enhances the ability to estimate accurately cardiac output and stroke volume by providing new access to left ventricular outflow tract in critically ill patients.

Aged↗
PubMed1994

Myocardial contrast echocardiography: enhancement of perfusion images by color coding.

To determine whether real-time color coding enhances the detection of myocardial perfusion through the use of echocardiographic contrast agents, we used a recently developed real-time color system during contrast injection in six open-chest dogs. Small amounts of echocardiographic contrast were injected into the left atrium. Short-axis epicardial images were obtained with a 5-MHz transducer before and after left anterior descending artery ligation. Gray-scale and rainbow-color map images were obtained for each contrast agent. The color map allowed detection of small increments in echo intensity that were not evident with routine gray-scale imaging. Thus, real-time color coding may improve the detection of myocardial perfusion with echocardiographic contrast agents.

Animals↗
PubMed1994

Quantification of left ventricular dimensions on line with biplane transesophageal echocardiography and lateral gain compensation.

To determine the feasibility and accuracy of biplane transesophageal echocardiography (TEE) with automatic boundary detection (ABD) for the estimation of left ventricular areas, we examined 19 consecutive patients with the use of this technique. In addition, we evaluated the utility of lateral gain compensation (LGC) to improve the online tracking of the ABD algorithm on the lateral endocardial-blood boundary of the echocardiographic image. The transverse plane short-axis TEE view and the longitudinal plane two chamber TEE view were used for the analysis. A semiquantitative estimate (in degrees) of the endocardial circumference, in which the boundary was correctly identified and tracked on line, improved from a mean of 198 degrees to 360 degrees with LGC (P less than 0.001). Results of comparisons of offline and online biplane TEE cavity areas revealed excellent correlations of values for the 16 patients (84%) in whom adequate transverse plane short-axis images were obtained (r values greater than 0.9 at systole and diastole). The correlation was also excellent (r values greater than 0.9) in the nine patients in whom longitudinal plane two-chamber views adequate for ABD analysis were obtained at systole and diastole. LGC significantly improved the accuracy of endocardial detection and tracking, which otherwise would be limited due to the anisotropic properties of the myocardium. Thus, ABD during biplane TEE may be feasible in a significant number of patients and accurately reflects left ventricular areas when compared with offline methods.

Echocardiography, Transesophageal↗
PubMed1994

Initial clinical experience with a miniature biplane transesophageal echocardiographic probe in adults.

Transesophageal echocardiography (TEE) is now routinely used in cardiovascular medicine. With improved technology the size of TEE probes has increased. Recently there has been interest in using smaller probes for adult TEE. We used a miniature 32-element, phased array biplane probe in 20 consecutive adults who underwent clinically indicated TEE evaluation. The miniature biplane probe was easily inserted without complication in all patients including one with thrombocytopenia and one with an esophageal stricture. Subjectively the probe was easier to insert and better tolerated by patients than standard adult TEE probes. High quality images of near-, mid-, and far-field structures were obtained in a majority of patients. Color Doppler identified mitral regurgitation in 12 (60%) patients, tricuspid regurgitation in ten (50%) patients, and aortic insufficiency in five (25%) patients. The miniature biplane TEE probe used in this study enhanced patient comfort without significant loss of image quality.

Adult↗
PubMed1994

Delineation of determinants of left ventricular early filling. Saline versus blood infusion.

BACKGROUND: Left atrial pressure (LAP) is often believed to play a dominant role in the determination of left ventricular (LV) early diastolic filling. In a previous study we found no significant relation between LAP and LV early filling velocity (E) but found instead a relation between E and two determinants of LV myocardial shortening (contractility and afterload). To determine if such disparate results may be related to the data ranges of the independent variables in a given population of animals, we took advantage of the differential hemodynamic effects of two modes of volume expansion: saline and whole blood. METHODS AND RESULTS: Eighteen closed-chest anesthetized dogs were instrumented with micromanometers for measurement of LV, left atrial, and aortic pressures. LV volumes were obtained with use of contrast ventriculography, pressures by micromanometry, and transmitral flow-velocity by Doppler echocardiography. After obtaining baseline measurements, group 1 (n = 9) received rapid infusion of 500 to 650 mL of saline over 10 minutes, and group 2 (n = 9) received the same volume infusion of whole blood. In terms of two known determinants of E, infusion of saline resulted in a significant increase in LAP at the moment of mitral valve opening (X1) (1.5 +/- 0.9 to 5.7 +/- 1.4 mm Hg; P < .05) and a moderate decrease in the pressure decay rate during isovolumic relaxation (tau 1/2) (22.9 +/- 2.4 to 26.3 +/- 3.5 milliseconds; P < .05). When these two factors were entered together into a multiple regression analysis with E as the dependent variable, the overall correlation was found to be significant (R = .722; P < .008), with both independent variables contributing significantly to the relation. When factors related to myocardial shortening (afterload and contractility) were added to this relation, they did not significantly improve the prediction of E. Like saline, whole blood infusion augmented X1 (1.6 +/- 2.4 to 8.8 +/- 3.2 mm Hg; P < .05) and tau 1/2 (21.5 +/- 2.6 to 32.0 +/- 6.3 milliseconds; P < .05) but also significantly increased LV afterload as measured by aortic diastolic pressure (91 +/- 10 to 110 +/- 12 mm Hg; P < .05). Multiple regression analysis of X1 and tau 1/2 with E again revealed a significant relation (R = .761; P < .002), with both independent variables contributing significantly to the relation. However, in this case, addition of contractility and afterload to the regression significantly improved the relation (R = .909; P < .001), with all four independent variables now contributing significantly to the prediction of E. CONCLUSIONS: Combined with our previous results, this study indicates the degree to which experimental methods can have an impact on the delineation of the determinants of a phenomenon as complex as LV early diastolic filling. Which independent variables emerge as primary determinants can be strongly influenced by the experimenter's choice of experimental design and manipulations. Specifically, experiments using volume infusion to delineate the responses of the cardiovascular system to variations in loading must allow for the hemodynamic changes that are inherent in the choice of infusate and infusion technique, especially when those interventions may significantly alter blood oxygen-carrying capacity and, in turn, differentially modify factors that affect the magnitude of the early diastolic transmitral pressure gradient.

Animals↗
PubMed1994

Atherosclerosis of the ascending aorta. Prevalence and role as an independent predictor of cerebrovascular events in cardiac patients.

BACKGROUND AND PURPOSE: The cause of cerebral and peripheral embolism remains undetermined in a significant number of patients. An atherosclerotic thoracic aorta has thus far been considered to be an uncommon one. METHODS: To define the potential role of the ascending thoracic aorta as an embolic source, intraoperative ultrasonic aortic imaging was performed in 1200 of 1334 consecutive patients aged 50 years and older who were undergoing cardiac surgery. Patients were divided into two groups according to the results of the ultrasound study in terms of presence or absence of atherosclerotic disease. The prevalence of previous neurological events in the two groups was characterized and compared. RESULTS: Ascending aortic atherosclerosis was present in 231 (19.3%) of the patients studied. Patients in this category were older (P < .0001). A higher percentage of them were smokers (P < .0001) compared with patients with less severe disease. Coronary artery disease was more extensive (P = .012), and a higher percentage of these patients had a history of peripheral vascular disease (P < .0001). Univariate analysis of the subjects with (n = 158) and without (n = 1042) previous neurological events indicated that age, body mass index, atrial fibrillation, hypertension, and atherosclerosis of the ascending aorta were associated significantly with previous occurrence of a cerebrovascular accident. For the group as a whole, multiple logistic regression analysis demonstrated that hypertension (odds ratio, 1.81; P = .002), atherosclerosis of the ascending aorta (odds ratio, 1.65; P = .013), and atrial fibrillation (odds ratio, 1.54; P = .060) were significantly and independently associated with the occurrence of previous neurological events. CONCLUSIONS: Atherosclerosis of the ascending aorta is an independent risk factor for cerebrovascular events. An atherosclerotic ascending aorta may represent a potential source of emboli or may be a marker of generalized atherosclerosis.

Age Factors↗
PubMed1994

Ultrasonic tissue characterization: integrated backscatter imaging for detecting myocardial structural properties and on-line quantitation of cardiac function.

Quantitative myocardial tissue characterization is being developed as an adjunct to conventional echocardiography to delineate the physical state of myocardium under diverse pathophysiological states. Real-time quantitative integrated backscatter imaging has made possible clinical investigations carried out in the United States, Europe, and Japan in patients with ischemic heart disease, hypertrophic cardiomyopathy, and cardiac allograft rejection, among others. A modification of the imaging processing used for characterization of tissue facilitates automatic detection of endocardial blood interfaces and on-line quantification of ventricular size and function, which has been recently introduced in clinical practice. Further progress and developments in quantitative ultrasonic imaging will place in perspective the clinical use of tissue characterization based on myocardial backscatter.

Animals↗
PubMed1993

Strategy for the reduction of stroke incidence in cardiac surgical patients.

Atherosclerosis of the ascending aorta (AAA) and severe carotid artery disease are risk factors for stroke in cardiac surgical patients. Twelve hundred of a consecutive series of 1,334 patients 50 years of age or older having a cardiac operation were screened for the presence of AAA by intraoperative ultrasonographic scanning and for the presence of carotid artery occlusive disease (791 of 798 patients > or = 65 years of age and younger symptomatic patients) by carotid duplex scanning. Coronary artery disease was present in 88% of the patients. Patients with moderate or severe AAA (n = 231; 19.3% of the total) were treated by ascending aortic replacement (n = 27) or by modified, less extensive techniques (n = 168) to avoid the atherosclerotic areas. Thirty-three patients had combined carotid endarterectomy and cardiac operation. Thirty-day mortality and stroke rates for the 1,200 patients were 4.0% and 1.6%, respectively. The stroke rate was low (1.1%) among the 969 patients with no or mild AAA. It was zero among 27 patients with moderate or severe AAA who had ascending aortic replacement and among the 33 patients who had carotid endarterectomy. The stroke rates were higher for 111 patients with moderate or severe ascending aortic disease who had only minor interventions (6.3%) and for 16 patients with severe carotid artery disease who did not have carotid endarterectomy (18.7%). Screening for AAA and carotid artery disease and aggressive surgical treatment of moderate or severe AAA and severe or symptomatic carotid artery disease appears to reduce the frequency of stroke in older cardiac surgical patients.

Aged↗
PubMed1993

Echocardiographic characterization of the improvement in right ventricular function in patients with severe pulmonary hypertension after single-lung transplantation.

OBJECTIVES: This study was designed to characterize immediate, early and long-term changes in right ventricular structure and function, as defined by two-dimensional and Doppler echocardiography, after single-lung transplantation in patients with severe pulmonary hypertension. BACKGROUND: Single-lung transplantation has recently been shown to dramatically improve hemodynamics in patients with primary pulmonary hypertension who had unsuccessful medical therapy. METHODS: Fourteen patients with severe pulmonary hypertension who underwent single-lung transplantation were studied with transthoracic and transesophageal two-dimensional and Doppler echocardiography. Right ventricular dimensions were measured in the apical four-chamber view. Right ventricular ejection and acceleration times and peak velocity of tricuspid regurgitation were measured by Doppler study. Results of right heart catheterization were available early (< 3 months) after transplantation in 10 of 13 patients and late after transplantation (6 months to 2 years) in 11 patients. RESULTS: In the early posttransplantation studies, right ventricular dimensions decreased and fractional area change and ejection fraction increased in all patients, but right ventricular wall thickness did not change significantly. Tricuspid regurgitation lessened markedly in all patients. Long-term decreases in right ventricular dimension and improvement in systolic function were sustained. Right ventricular wall thickness significantly decreased compared with the early postoperative value (0.76 +/- 0.1 cm compared with 0.63 +/- 0.14 cm, p < 0.02). CONCLUSIONS: Two-dimensional echocardiography demonstrates sustained improvement in right ventricular function after single-lung transplantation for severe pulmonary hypertension despite severe preoperative dysfunction.

Cardiac Catheterization↗
PubMed1993

Hemodynamic effects of atrial interaction.

BACKGROUND: Ventricular pressure and volume overload may induce hemodynamically important ventricular interactions mediated by the thick interventricular septum. The purpose of this study was to determine whether analogous hemodynamically manifest atrial interactions occur across the thinner interatrial septum. METHODS: Right atrial (RA) and left atrial (LA) pressures were measured with micromanometer-tipped catheters before and after atrial pressure and volume overload elicited by sequential right ventricular (RV), RA, and septal ischemia induced in nine open-chest dogs. RESULTS: Following RV ischemia, RA pressure increased and RA contraction and relaxation were enhanced, as indicated by an augmented A wave and X descent. Despite decreased LV diastolic size, LA pressure increased, with similar increases in its A wave and X descent. RA ischemia depressed RA contraction and relaxation, resulting in diminished A wave and X descent. Parallel changes occurred in the LA waveform. Following septal ischemia, LA contraction and relaxation were enhanced, as reflected in an augmented A wave and X descent. Despite persistent RA ischemia, the RA A wave and X descent increased. CONCLUSIONS: These findings demonstrate interatrial transmission of pressure and waveform changes that may influence hemodynamic evaluation and cardiac function.

Animals↗
PubMed1993

Comparison of color flow imaging and peripheral venous saline contrast during transesophageal echocardiography to evaluate right-to-left shunt at the atrial level.

Intravenous injections of agitated saline (contrast) are used to identify right-to-left atrial shunt during transesophageal echocardiography (TEE). Color flow imaging (CFI) with TEE can be used to detect left-to-right atrial shunt but its application to detect right-to-left shunt is not known. We performed CFI and contrast during TEE in 72 patients for detection of right-to-left shunt. Frame-by-frame review of CFI demonstrated discrete laminar jets of the left side of the atrial septum at the lower or upper margin of the fossa ovalis (FO) in 41 (57%) of 72; only 22 had positive contrast. Timing of shunts was late diastolic or early systolic and not related to pulmonary venous inflow. The length of the FO at end-systole was greater in those with positive CFI compared to negative CFI (13.5 +/- 5 vs 11 +/- 4 mm, P = 0.02). CFI was positive for right-to-left shunt in ten of 14 with atrial septal aneurysms. Contrast was positive for right-to-left shunt in 29 (40%) of 72; all but six had positive CFI. The degree of left atrial opacification was minimal in 19 and moderate to severe in ten. FO size was greater in positive versus negative contrast (14 +/- 4 vs 11 +/- 5 mm, P = 0.02). Contrast was positive for shunt in ten of 14 with septal aneurysms. Thus, right-to-left atrial shunt more often occurs with increased FO size and septal aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Determinants of the recovery of right ventricular performance following experimental chronic right coronary artery occlusion.

BACKGROUND: Patients with acute ischemic right ventricular dysfunction often develop hemodynamic compromise, yet most manifest spontaneous early clinical improvement and later recovery of global right ventricular performance. This study was designed to delineate the determinants of right ventricular performance following chronic right coronary artery occlusion. METHODS AND RESULTS: Thrombotic right coronary artery occlusion was induced in 16 closed-chest dogs. Acute occlusion depressed right ventricular free wall motion (motion score, 1.0 +/- 0.0 to 3.4 +/- 0.1*) and global performance (right ventricular fractional area change, 29.2 +/- 1.8% to 2.3 +/- 1.9%*). There was right ventricular dilatation and reversed septal curvature, with elevated and equalized diastolic filling pressures. At 5 days, despite persistent severe right ventricular free wall dysfunction (motion score, 3.4 +/- 0.1 to 2.7 +/- 0.1*), global right ventricular performance improved (fractional area change, 2.3 +/- 1.9% to 17.0 +/- 3.8%*), in part due to reduced right ventricular free wall dyskinesis associated with increased right ventricular free wall end-diastolic thickness. At 7 weeks, collateral flow had restored right ventricular free wall perfusion to baseline values. The increased right ventricular free wall thickness had resolved, right ventricular free wall motion was improved (2.7 +/- 0.1 to 1.6 +/- 0.1*), and global right ventricular performance had recovered further (17.0 +/- 3.8 to 20.9 +/- 0.9). Right ventricular dilatation was reduced, septal curvature normalized, and there was resolution of equalized filling pressures. Histopathological analysis demonstrated minimal right ventricular infarction. CONCLUSIONS: Acute right coronary artery occlusion results in right ventricular free wall dyskinesis and depressed global right ventricular performance. Global right ventricular function improves early, in part due to reduced right ventricular free wall dyskinesis associated with increased right ventricular free wall diastolic thickness. Collateral restoration of perfusion facilitates late recovery of right ventricular free wall function (*P < .05).

Animals↗
PubMed1993

On-line assessment of left atrial area and function by echocardiographic automatic boundary detection.

BACKGROUND: Direct assessment of left atrial (LA) function has not been previously performed by noninvasive techniques; rather, LA function has been evaluated only indirectly via the analysis of transmitral flow velocity by Doppler. The recent development of real-time two-dimensional echocardiographic automatic boundary detection suggests that LA dimensions can be measured instantaneously to provide on-line assessment of its systolic and diastolic functions. METHODS AND RESULTS: We performed echocardiographic assessment of LA dimensions and function with automatic boundary detection in 45 patients by using the apical four-chamber view. Thirty-seven patients had structural or functional cardiac abnormalities, 35 patients were in sinus rhythm, and 10 patients had atrial fibrillation. Moderate to severe mitral regurgitation (MR) was noted in 16 patients. We also studied 10 control subjects to assess normal values of LA cavity area and indexes of function. From the instantaneously derived LA area, we derived indexes of systolic atrial expansion and diastolic atrial emptying. There were excellent correlations between the on-line-derived LA areas and those measured off line from videotaped images of conventional echocardiography (r = .91 for end-diastolic and .93 for end-systolic areas; SEE, 4.0 and 3.8 cm2, respectively). Patients in atrial fibrillation had depressed diastolic emptying index (0.17 +/- 0.05) compared with those in sinus rhythm (0.28 +/- 0.12; P < .02). Furthermore, patients with chronic MR exhibited larger LA cavity areas and depressed systolic and diastolic LA function as compared with those without MR. In addition, the Doppler-determined mitral E/A ratio was related to the ratio of early diastolic-to-late diastolic change in LA cavity area (r = .79; SEE 0.6; n = 35). CONCLUSIONS: Instantaneous LA cavity area measurement by echocardiographic automatic boundary detection is accurate and feasible in patients with diverse cardiac disorders. Patients with atrial fibrillation had a depressed diastolic emptying index and those with significant mitral regurgitation had depressed systolic expansion index as well. LA functional indexes in both systole and diastole can be derived providing an approach for quantitative evaluations of left atrial-left ventricular interactions based on geometric assessment noninvasively.

Atrial Fibrillation↗