PubMed Health⌕ Search

Biomedical subjects

R Shabetai

Publications and source records attributed to R Shabetai.

At least 19 recordsLinked to original sources
PubMed1992

The importance of tricuspid valve structure and function in the surgical treatment of rheumatic mitral and aortic disease.

A significant proportion of individuals with rheumatic disease have tricuspid valve involvement which may be clinically important and alter the medical or surgical approach to treatment. Therefore 50 patients with rheumatic left-sided valvular lesions who were referred for operative treatment were studied. Thirty patients had angiographically significant tricuspid regurgitation (group I) and 20 had a competent tricuspid valve (group II). Pre-operative cardiac assessment included Doppler echocardiography and contrast ventriculography. Patients with tricuspid regurgitation more commonly had mitral valve disease or combined mitral and aortic valve lesions, (P less than 0.001) and were more likely to have atrial fibrillation than those without tricuspid regurgitation (P less than 0.001). Pulmonary arterial systolic and mean right atrial pressures were higher in group I (both P less than 0.01). A close relationship was found between the angiographic and Doppler assessment of the degree of tricuspid regurgitation (P less than 0.01). Doppler-derived measurement of the right ventricular-right atrial systolic pressure difference correlated well with the systolic trans-tricuspid pressure difference measured at cardiac catheterization (y = 0.7x + 22, r = 0.67, P less than 0.001) and the pulmonary arterial systolic pressure (y = 0.8x + 27, r = 0.71, P less than 0.001). Rheumatic involvement of the tricuspid valve identified by pre-operative echocardiography was confirmed in five patients at surgery. Of the 13 patients with functional tricuspid regurgitation at operation, only two had been diagnosed as having organic disease by echocardiography. Furthermore, in all 18 cases where Doppler suggested grade 3 or 4+ tricuspid regurgitation, surgical repair or replacement of the valve was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Heart size and maximal cardiac output are limited by the pericardium.

We tested the hypothesis that the pericardium, by restricting heart size, limits maximal cardiac output and oxygen consumption. We studied 15 pigs. Five underwent maximal treadmill running before and 14-21 days after thoracotomy and pericardiectomy; these pigs also received sequential volume infusions to determine end-diastolic pressure-dimension relationships. Five underwent maximal treadmill running before and 14-21 days after thoracotomy (pericardium undisturbed) to determine the effect of thoracotomy on exercise performance. Finally, five underwent thoracotomy, instrumentation, loose closure of the pericardium, and sequential volume infusions to determine the effect of thoracotomy without pericardiectomy on end-diastolic pressure-dimension relationships. Pericardiectomy caused similar increases in maximal cardiac output (29% increase; P = 0.007) and maximal oxygen consumption (31% increase; P = 0.02). These results were associated with increased left ventricular end-diastolic dimension (10% increase; P = 0.01) and an estimated 33% increase in end-diastolic volume. In addition, left ventricular mass was increased by pericardiectomy (18% increase; P < 0.04). Thus the pericardium, by limiting utilization of the Starling mechanism, limits maximal cardiac output, and the limit to cardiorespiratory performance lies not in oxygen utilization, but in oxygen delivery. Furthermore, removal of pericardium is associated with myocardial hypertrophy.

Animals↗
PubMed1992

Digital image analysis of shark gills: modeling of oxygen transfer in the domain of time.

Digital radiographic imaging of blood circulation through leopard shark gills establishes a secondary lamellar transit time of 6.5 s. This duration, combined with estimates of cardiac output and hemoglobin-oxygen affinity, permits novel modeling of gill oxygen transfer in the time domain. The temporal model allows assessment of factors contributing to previously noted discrepancies between physiological and morphometric branchial oxygen conductance estimates. Lamellar transit time for shark blood is 20 times greater than human alveolar transit time, and thus correlates with a slower rate of hemoglobin-oxygen binding and a greater diffusion distance.

Animals↗
PubMed1992

The role of the pericardium in conditioning the effects of physical training.

More work needs to be done on the extent to which the pericardium can modulate the cardiovascular response to exercise and the mechanisms whereby this modulation is brought about. Studies are needed to differentiate the effects of the pericardium on the cardiovascular exercise response, comparing trained with untrained subjects. Evidence is accumulating that exercise training in patients with heart failure improves not only the performance of exercising muscles, but also has some beneficial effects on central hemodynamics. The extent to which these beneficial effects can be attributed to conditioning the pericardium remains speculative.

Adaptation, Physiological↗
PubMed1992

Controversial issues in restrictive cardiomyopathy.

The topic of restrictive cardiomyopathy remains controversial for many reasons. The term cardiomyopathy is unfortunately sometimes used interchangeably with diastolic heart failure. Furthermore, diastolic heart failure is sometimes linked with other causes of diastolic dysfunction such as hypertrophic cardiomyopathy and mitral valve disease. Restrictive cardiomyopathy is a clinical entity of primary or secondary myocardial disease presenting a picture that closely simulates that of constrictive pericarditis. In the majority of cases the correct diagnosis can be arrived at following a careful paradigm that begins with history and may end with endomyocardial biopsy. Many of the old teachings about how to distinguish restrictive cardiomyopathy from constrictive pericarditis have not held up with time and clinical experience: in particular equal diastolic pressures on both sides of the heart are compatible with either restrictive cardiomyopathy or constrictive pericarditis.

Biopsy↗
PubMed1991

Pericardial influences on right and left ventricular filling dynamics.

The influence of the pericardium on right and left ventricular filling was studied using two-dimensional and Doppler echocardiography in 14 open-chest dogs. Doppler echo parameters of filling included early (E) and late (A) velocities and their ratio (E/A) for the mitral and tricuspid valves. Right and left ventricular volumes were calculated from orthogonal two-dimensional echocardiographic images. Data were compared at three levels of left ventricular end-diastolic pressure (6 +/- 2, 13 +/- 3, and 21 +/- 4 mm Hg) at matched heart rates before and after pericardiectomy. The instantaneous diastolic pressure gradient was measured in 12 of the dogs. Pericardiectomy resulted in an increase in early mitral velocity, peak early diastolic pressure gradient, and E/A but not early mitral velocity normalized for end-diastolic volume. In contrast, for the tricuspid valve flow, pericardiectomy did not change E but caused a marked increase in A and a decrease in E/A. Right ventricular end-diastolic volumes at matched left ventricular end-diastolic volumes were similar before and after the pericardium was removed. However, removal of the pericardium caused a significant decrease of the slope for the right (86.0 +/- 27.0 x 10(-4) versus 50.0 +/- 19.5 x 10(-4) mm Hg/ml, p less than 0.01), but not left, ventricular ln end-diastolic pressure-volume relation (21.2 +/- 9.2 x 10(-3) versus 21.4 +/- 5.3 x 10(-3) mm Hg/ml, p = NS), and a decrease of the pressure intercept for the left (3.0 +/- 2.0 versus 1.6 +/- 0.9 mm Hg, p less than 0.05), but not right, ventricular ln end-diastolic pressure-volume relation (2.8 +/- 1.4 versus 1.4 +/- 0.8 mm Hg, p = NS). In conclusion, filling of the two ventricles is affected by the pericardium over a wide range of physiological ventricular volumes and pressures. At matched left ventricular end-diastolic volume, pericardiectomy causes a fundamental alteration in right, but not left, ventricular filling.

Animals↗
PubMed1991

Effects of mental exercise in patients with dilated cardiomyopathy and congestive heart failure. An echocardiographic Doppler study.

To assess the effects of mental stress on left ventricular diastolic function in patients with congestive heart failure, nine patients aged 57 +/- 12 years with dilated cardiomyopathy (end-diastolic volume, more than 110 ml/m2; ejection fraction, less than 40%; mean, 28 +/- 8%) and congestive heart failure in New York Heart Association functional class II or III and 14 normal volunteers (mean age, 49 +/- 8 years) were studied during mental arithmetic lasting 10 minutes with echocardiographic Doppler monitoring of transmitral flow velocity. During mental arithmetic, the ratio of peak flow velocity in early versus late diastole (E/A) and deceleration time of early diastole did not change in normal controls. However, E/A increased significantly (from 1.6 +/- 1.5 to 1.9 +/- 1.7; p less than 0.01) and deceleration time markedly decreased (from 156 +/- 49 to 108 +/- 31 msec; p less than 0.001) in patients with congestive heart failure. In 16 postinfarct patients with ejection fraction of less than 40% studied during mental arithmetic with simultaneous hemodynamics and Doppler recordings, good correlations were found between pulmonary wedge pressure and Doppler parameters (wedge pressure versus E/A, r = 0.89; wedge pressure versus deceleration time, r = -0.87). During mental arithmetic, the pulmonary wedge pressure-E/A correlation was weaker (r = 0.67), whereas the correlation between pulmonary wedge pressure and deceleration time was stronger (r = 0.91). The value of 153 msec in deceleration time was the best cutoff point in predicting 12 mm Hg pulmonary wedge pressure, both at rest and during mental arithmetic: the higher the deceleration time, the lower the pulmonary wedge pressure, and vice versa. Among patients with congestive heart failure, five showed normal baseline deceleration time (195 +/- 21 msec; pattern 1), and the remaining four showed a short (less than 153 msec) deceleration time (108 +/- 13 msec; pattern 2). During mental arithmetic, deceleration time markedly decreased to as short as 119 +/- 20 msec in all patients except one with baseline pattern 1. Deceleration time further decreased to 75 +/- 6 msec in all patients with baseline pattern 2. Mental arithmetic induces changes in left ventricular diastolic function in patients with congestive heart failure. Transmitral echocardiographic Doppler provides a simple noninvasive method of estimating and monitoring pulmonary wedge pressure in patients with severe left ventricular dysfunction.

Cardiomyopathy, Dilated↗
PubMed1990

Regional left ventricular wall motion abnormalities in idiopathic dilated cardiomyopathy.

An evaluation and a comparison of left ventricular regional wall motion were performed in 32 patients with idiopathic dilated cardiomyopathy, none of whom had coronary artery diameter stenosis exceeding 20% in any major artery, and 17 control subjects, using frame by frame video intensity analysis of digitized ventriculograms. This technique evaluates the whole cardiac cycle in short overlapping intervals and yields information for systolic and diastolic events, without assumptions regarding the position and orientation of the ventricle. Diastolic regional wall motion abnormalities were found in 31 of 32 patients and systolic abnormalities were present in 16 patients. Asynchronous regions most commonly detected during diastole were anteroapical and apical; they were found in 19 of 32 patients. Regional contraction abnormality was observed in the apical and the anteroapical regions in 6 of 16 patients. Dilatation-induced changes in left ventricular shape exaggerate the phenomenon of higher wall stress at the apex of the normal ventricle. Basal wall motion is thus relatively preserved in dilated cardiomyopathy.

Adult↗
PubMed1990

Detection and quantitation of ischemic left ventricular dysfunction using a new video intensity technique for regional wall motion evaluation.

Eighty patients with ischemic heart disease and 17 normal subjects were evaluated for left ventricular regional wall motion by means of a new method. The wall motion analysis is based on video intensity. This technique uses a temporally sliding analysis to evaluate the cardiac cycle in 100 msec intervals. Presence of coronary artery disease was defined as more than 50% measured diameter stenosis. Wall motion abnormalities in regions perfused by stenotic vessels were most common in early diastole (76%). Sensitivity of this method at rest in patients with coronary artery disease was 79.7% (p less than 0.0001) and overall accuracy was 84.2% (p less than 0.0001). Abnormalities in both systole and diastole were more common in regions perfused by severe lesions (greater than 75%) than in those perfused by moderately stenotic (less than 75%) vessels (p less than 0.05). A comparison of the new method with phase and amplitude analysis was performed in 15 patients and with two-frame analysis in 40 patients. This new method yielded a higher sensitivity than either of the other two methods.

Adult↗
PubMed1990

Prediction of outcome in late-stage cardiomyopathy.

One hundred thirty-three patients with dilated heart failure, 80 with coronary artery disease, and 53 with idiopathic dilated cardiomyopathy were followed for a mean of 29 months. Patients with ischemic heart disease had a worse prognosis than those classified as having idiopathic cardiomyopathy. Features from history, physical examination, and diagnostic tests done when patients were referred to our clinic were checked for univariate association with survival and were used in Cox model survival analysis to define risk groups. Neither the overall group nor either subgroup showed a relationship between ejection fraction and survival. The best variables for predicting long-term mortality included underlying coronary artery disease, basal systolic blood pressure of less than 120 mm Hg, presence of congestion on chest radiogram, and age over 64. Other variables did not improve risk prediction in the overall group. Among patients with ischemic heart disease, blood pressure, congestion, maximal heart rate on treadmill test, and the presence of left bundle branch block on the initial electrocardiogram all contributed. Only systolic blood pressure and the symptom score were related to survival in idiopathic cardiomyopathy.

Aged↗
PubMed1990

Selective beta-1-adrenoceptor partial agonist treatment for congestive heart failure.

Xamoterol is a beta-adrenoceptor partial agonist which selectively acts at the beta 1-receptors of the heart. The partial agonist effect modestly increases myocardial contractility and appears also to improve diastolic function and cardiac output without an increase in myocardial oxygen demand. Improved myocardial performance is maintained during exercise while increased heart rate is attenuated. Partial agonist activity protects against tachyphylaxis and arrhythmogenicity. With chronic treatment, exercise duration and work capacity increase and clinical manifestations of heart failure are reduced.

Adrenergic beta-Agonists↗
PubMed1990

Acute pericarditis.

Acute pericarditis may be of viral or idiopathic origin, may be induced by certain drugs, may occur as a consequence of thoracic surgery, may result from infection by bacteria or other organisms, or may be associated with noninfectious systemic disease. In some instances, pericarditis may be detected quickly, and in other cases it may not be recognized until late. This article discusses clinical findings, clinical course, and treatment of acute pericarditis. In addition, diagnosis and treatment of pericardial effusion are presented.

Acute Disease↗
PubMed1989

A comparison of oral milrinone, digoxin, and their combination in the treatment of patients with chronic heart failure.

We randomly assigned 230 patients in sinus rhythm with moderately severe heart failure to treatment with digoxin, milrinone, both, or placebo. The effects of each were compared during a 12-week, double-blind trial. Treatment with milrinone or digoxin significantly increased treadmill exercise time as compared with placebo (by 82 and 64 seconds respectively; 95 percent confidence limits, 44 and 123, and 30 and 100). Both treatments reduced the frequency of decompensation from heart failure, from 47 percent with placebo to 34 percent with milrinone (P less than 0.05; 95 percent confidence limits, 22 and 46) and 15 percent with digoxin (P less than 0.01; 95 percent confidence limits, 7 and 26). However, the clinical condition of 20 percent of the patients taking milrinone deteriorated within two weeks after treatment was begun, as compared with only 3 percent of those taking digoxin (P less than 0.05). The left ventricular ejection fraction at rest was not significantly changed by milrinone (+0.2 percent; 95 percent confidence limits, -1.5 and 1.9), but it was increased by digoxin (+1.7 percent; P less than 0.01; 95 percent confidence limits, -0.03 and 3.4) and decreased by placebo (-2.0 percent; 95 percent confidence limits, -3.8 and -0.1). Three-month survival was related inversely to the base-line ejection fraction. Analysis of mortality from all causes according to the intention to treat suggested an adverse effect of milrinone (P = 0.064). After adjustment for an excess of patients with lower ejection fractions randomly assigned to receive milrinone, this trend was not significant (P = 0.26). Increased ventricular arrhythmias occurred more frequently in patients who received milrinone than in those who did not (18 vs. 4 percent; P less than 0.03). We conclude that milrinone significantly increased exercise tolerance and reduced the frequency of worsened heart failure. However, in the population of patients studied, milrinone or the combination of milrinone and digoxin offered no advantage over digoxin alone. Furthermore, our data suggest that milrinone may aggravate ventricular arrhythmias.

Administration, Oral↗
PubMed1989

Complications of cardiac catheterization and angiography in patients with valvular heart disease. VA Cooperative Study on Valvular Heart Disease.

Complications were surveyed prospectively in 2,029 catheterizations performed on 1,483 patients from the 13 centers participating in the VA Cooperative Study on Valvular Heart Disease. Complications were reported in 6.9% of 1,559 preoperative procedures of which 2.6% were major and 0.2% fatal. Clinical predictors of complications were hypertension and the precatheterization diagnosis of aortic stenosis. Nevertheless, patients with aortic stenosis successfully tolerated left ventriculography, which was routinely performed regardless of the magnitude of gradient. Procedural predictors of complication were brachial arteriotomy (vascular occlusion) and transseptal catheterization (tamponade). Among the 470 postoperative catheterizations performed solely for research purposes, there were six complications, of which five were bleeding events in patients taking warfarin. Transseptal catheterization was safer in postoperative patients with no cases of tamponade in 125 procedures.

Cardiac Catheterization↗
PubMed1989

Myocarditis and dilated cardiomyopathy: twins or distant relatives?

Myocarditis and dilated cardiomyopathy both commonly present as new unexplained heart failure. This similarity raises the question of the interrelation of these disorders. What proportion of dilated cardiomyopathy begins as myocarditis, what other cardiac insults commonly lead to myocarditis and how often endomyocardial biopsy yields the diagnosis of myocarditis when present, are unknown. Proof that immunosuppressive treatment of myocarditis is beneficial is also lacking.

Biopsy↗