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Biomedical subjects

A J Labovitz

Publications and source records attributed to A J Labovitz.

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

Effect of mitral regurgitation on pulmonary venous velocities derived from transesophageal echocardiography color-guided pulsed Doppler imaging.

The effect of mitral regurgitation on pulmonary venous flow velocity was studied in 66 patients undergoing transesophageal echocardiography. Nine patients were studied intraoperatively before and after surgery, so that 75 pulmonary venous flow tracings were analyzed. Fifty-four patients had no significant (0 to 1+) mitral regurgitation and 21 had significant (2 to 3+) mitral regurgitation. Comparison of both groups revealed significant differences in the pulmonary venous flow pattern. In patients with no significant mitral regurgitation, the peak systolic velocity was higher (55 +/- 16 vs. -4 +/- 16 cm/s; p less than 0.0001) and the peak diastolic velocity was lower (43 +/- 13 vs. 59 +/- 17 cm/s; p less than 0.01) when compared with values in patients with significant mitral regurgitation. Consequently, the peak systolic/diastolic velocity ratio was significantly higher in the patients without significant mitral regurgitation (1.4 +/- 0.5 vs. 0.4 +/- 1.3; p less than 0.0001). The same trend was noted with respect to the systolic and diastolic velocity integrals. As the degree of mitral regurgitation increased, the peak diastolic velocity and diastolic velocity integral increased, whereas the peak systolic velocity and systolic velocity integral decreased. In patients with severe mitral regurgitation, the systolic flow became reversed (retrograde). The sensitivity of reversed systolic flow for severe mitral regurgitation was 90% (9 of 10), the specificity was 100% (65 of 65), the positive predictive value was 100% (9 of 9), the negative predictive value was 98% (65 of 66) and the predictive accuracy was 99% (74 of 75).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Superiority of transesophageal echocardiography in detecting cardiac source of embolism in patients with cerebral ischemia of uncertain etiology.

The diagnostic yield of transesophageal and transthoracic echocardiography for identifying a cardiac source of embolism was compared in 79 patients presenting with unexplained stroke or transient ischemic attack. There were 35 men and 44 women with a mean age of 59 years (range 17 to 84); 52% had clinical cardiac disease. Both transthoracic and transesophageal echocardiograms were performed using Doppler color flow and contrast imaging. Transesophageal echocardiography identified a potential cardiac source of embolism in 57% of the overall study group compared with only 15% by transthoracic echocardiography (p less than 0.0005). Compared with transthoracic echocardiography, transesophageal echocardiography more frequently identified atrial septal aneurysm associated with a patent foramen ovale (9 versus 1 of 79 patients, p less than 0.005), left atrial thrombus or tumor (6 versus 0 of 79 patients, p less than 0.05) and left atrial spontaneous contrast (13 versus 0 of 79 patients, p less than 0.0005). All cases of left atrial thrombus or spontaneous contrast were identified in patients with clinically identified cardiac disease. In the 38 patients with no cardiac disease, transesophageal echocardiography identified isolated atrial septal aneurysm and atrial septal aneurysm with a patent foramen ovale more frequently than transthoracic echocardiography (8 versus 2 of 38 patients, p less than 0.05). The two techniques had a similar rate of identifying apical thrombus and mitral valve prolapse. Overall, transesophageal echocardiography identified abnormalities in 39% of patients with no cardiac disease versus 19% for transthoracic echocardiography (p less than 0.005). Thus, transesophageal echocardiography identifies potential cardiac sources of embolism in the majority of patients presenting with unexplained stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Infarction↗
PubMed1991

Echocardiographic evaluation of cardiac structure and function in elderly subjects with isolated systolic hypertension.

One hundred four participants in the Systolic Hypertension in the Elderly Program (SHEP) trial (mean age 71 +/- 6 years) were examined by Doppler echocardiography to gain information on the cardiac structural and functional alterations in isolated systolic hypertension. Participants had a systolic blood pressure greater than 160 mm Hg with diastolic blood pressure less than 90 mm Hg and were compared with 55 age-matched normotensive control subjects. Left ventricular mass index was significantly higher in the participants than in the normotensive subjects (103 +/- 28 versus 87 +/- 23 g/m2, p = 0.0014) and 26% of the participants met echocardiographic criteria for left ventricular hypertrophy compared with 10% of normotensive subjects. Left atrial index was also greater in participants than in normotensive subjects (2.26 +/- 0.32 versus 2.11 +/- 0.24 cm/m2, p = 0.005) and 51% of participants had left atrial enlargement. Doppler measures of diastolic filling were significantly different between the two groups, with peak atrial velocity higher (76 +/- 17 versus 69 +/- 17 cm/s, p = 0.02) and ratio of peak early to atrial velocity lower (0.76 +/- 0.23 versus 0.86 +/- 0.22, p = 0.0124) in participants. There was no correlation between left ventricular mass index and Doppler measures of diastolic function, but relative wall thickness correlated significantly with peak atrial velocity (r = 0.22, p = 0.016) and peak early to peak atrial velocity ratio (r = 0.24, p = 0.007). There was no difference in M-mode ejection phase indexes of systolic performance (shortening fraction and peak velocity of circumferential fiber shortening) between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Evaluation of pulmonary venous flow by transesophageal echocardiography in subjects with a normal heart: comparison with transthoracic echocardiography.

Nineteen normal subjects and five patients with atrial fibrillation underwent transesophageal and transthoracic echocardiographic studies to evaluate the normal pulmonary venous flow pattern, compare right and left pulmonary venous flow and assess the effect of sample volume location on pulmonary venous flow velocities. Best quality tracings were obtained by transesophageal echocardiography. Anterograde flow during systole and diastole was observed in all patients by both techniques. Reversed flow during atrial contraction was observed with transesophageal echocardiography in 18 of the 19 subjects in normal sinus rhythm, but in only 7 subjects with transthoracic echocardiography. Two forward peaks during ventricular systole were clearly identified in 14 subjects (73%) with transesophageal echocardiography, but in none with the transthoracic technique. The early systolic wave immediately followed the reversed flow during atrial contraction and was strongly related to the timing of atrial contraction (r = 0.78; p less than 0.001), but not to the timing of ventricular contraction, and appeared to be secondary to atrial relaxation. Conversely, the late systolic wave was temporally related to ventricular ejection (r = 0.66; p less than 0.001), peaking 100 ms before the end of the aortic valve closure and was unrelated to atrial contraction time. Quantitatively, significantly higher peak systolic flow velocities were obtained in the left upper pulmonary vein compared with the right upper pulmonary vein (60 +/- 17 vs. 52 +/- 15 cm/s; p less than 0.05) and by transesophageal echocardiography compared with transthoracic studies (60 +/- 17 vs. 50 +/- 14 cm/s; p less than 0.05). Increasing depth of interrogation beyond 1 cm from the vein orifice resulted in a significant decrease in the number of interpretable tracings.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Evaluation of mitral regurgitation by Doppler echocardiography.

The diagnosis and assessment of mitral regurgitation has been one of the main challenges for cardiac ultrasound. Imaging techniques (M-mode and two-dimensional echocardiography) provide direct morphologic and etiologic information of the evaluation of patients with suspected mitral regurgitation. The advent of cardiac Doppler increased tremendously the ability to evaluate mitral regurgitation noninvasively. Continuous-wave and pulsed Doppler have been found to be sensitive and specific in the detection of mitral regurgitation. The introduction of color flow Doppler simplified enormously the assessment of patients with suspected mitral regurgitation. The maximal regurgitant area and maximal regurgitant area corrected for left atrial size have become the most commonly used parameters to evaluate mitral regurgitation by color flow Doppler in the clinical setting. However, the color regurgitant jet area is highly dependent on anatomical, hemodynamic, and equipment factors. A new method, based on the proximal isovelocity surface area, is being evaluated and appears to be relatively independent of equipment factors. Transesophageal echocardiography has been shown to be exquisitely sensitive in the detection of mitral regurgitation. Quantitation of mitral regurgitation by transesophageal echocardiography is currently based on the maximal regurgitant area and this parameter appears to correlate closely with the angiographic degree of mitral regurgitation. Pulmonary venous flow analysis had been used in conjunction with color flow mapping for the evaluation of mitral regurgitation by transesophageal echocardiography. The presence of reversed systolic flow has been shown to be sensitive and specific for the diagnosis of severe mitral regurgitation. Patients with clinically difficult surface studies, flail mitral valve leaflets, and prosthetic mitral valve are best evaluated by the transesophageal approach with interrogation of pulmonary venous flow.

Blood Flow Velocity↗
PubMed1991

Applications of Doppler echocardiography in cardiac pacing.

The purpose of this article is to review the use of Doppler echocardiography for assessing responses during cardiac pacing. Doppler techniques allow the physician to select the optimal mode pacemaker and pacemaker settings with regard to heart rate and atrioventricular delay, at rest and during exercise. Doppler parameters can be used to predict the relative hemodynamic advantage of dual chamber or rate adaptive pacing over fixed rate pacing. This valuable noninvasive modality may enhance the benefit of pacemaker therapy.

Cardiac Pacing, Artificial↗
PubMed1990

Prevalence and clinical implications of atrial spontaneous contrast in patients undergoing transesophageal echocardiography.

The prevalence of atrial spontaneous contrast was evaluated in 150 consecutive patients undergoing transesophageal echocardiography. Spontaneous contrast was observed in 29 patients (19%). It was seen in the left atrium in 24 patients, in the right atrium in 4 patients and in both atria in 1 patient. Spontaneous atrial contrast was not seen in the absence of an associated cardiac abnormality. Univariate analysis showed a significant relation between the presence of spontaneous contrast and significant mitral regurgitation (p less than 0.05), the presence of mitral valve prostheses (p less than 0.001), atrial fibrillation (p less than 0.0001) and left atrial size (p less than 0.001). Multivariate analysis showed that the presence of atrial fibrillation, prosthetic mitral valve and atrial size were independent factors for the presence of spontaneous contrast. However, of the 29 patients with spontaneous contrast, 13 (45%) were in sinus rhythm and in only 4 (16%) was the left atrial size greater than 60 mm. Left atrial thrombus was detected in 9 of the 150 patients. Although spontaneous contrast was noted in 5 (55%) patients with left atrial thrombus and in only 20 (14%) patients without left atrial thrombus (p less than 0.001), none of the 3 patients who had right atrial thrombus had spontaneous contrast in that chamber. Overall, 7 (58%) of the 12 patients with right or left atrial thrombi had no evidence of spontaneous contrast. Multivariate analysis showed that atrial fibrillation was the only independent clinical predictor of left atrial thrombus. Thus, spontaneous echocardiographic contrast is a common phenomenon observed in approximately 20% of the patients undergoing transesophageal echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Spontaneous echocardiographic contrast in the descending aorta.

The visualization of echocardiographic spontaneous contrast is a common phenomenon in patients undergoing transesophageal echocardiographic studies. Its pathophysiology is not well understood, but it has been related to the presence of a low flow state in the cardiac chambers. We report the presence of spontaneous contrast in the descending aorta of four patients, a location not previously described in the absence of aortic dissection. In two patients, spontaneous contrast was noted in both the left atrium and the descending aorta. In one patient with moderate left ventricular dysfunction, spontaneous contrast was noted in the descending aorta and in the left ventricle. In the remaining case, no cardiac or aortic abnormalities were observed and this represents the first time that spontaneous contrast has been identified in a patient with an echocardiographically normal heart. The occurrence of spontaneous contrast has been considered an abnormal echocardiographic finding, since it has always been described in patients with clinical symptoms and cardiac abnormalities. The fact that spontaneous contrast can be visualized in patients with very mild structural cardiac abnormalities or none at all, warrants further investigation, especially when therapeutic or prognostic implications are considered.

Aged↗
PubMed1990

Color Doppler echocardiographic evaluation of patients with a flail mitral leaflet.

Chordal rupture with a subsequent flail mitral valve leaflet is now the most common cause of pure mitral regurgitation. To describe the Doppler color flow findings in flail mitral leaflet and the determinants of these findings, Doppler color flow mapping and conventional Doppler echocardiography were performed in 31 consecutive patients presenting with a flail mitral leaflet. In the 23 patients with a posterior flail leaflet, a distinctive highly eccentric and turbulent jet directed toward the posterior wall of the aorta was noted. In the eight patients with an anterior flail leaflet, a jet directed toward the posterolateral left atrial wall was noted. Maximal regurgitant jet area was significantly larger in patients with a flail anterior leaflet (13.1 +/- 3.0 cm2) than in those with a flail posterior leaflet (5.8 +/- 3.0 cm2, p = 0.0001). Maximal jet area to left atrial ratio was also significantly higher in those with a flail anterior leaflet (0.56 +/- 0.16) than in those with a flail posterior leaflet (0.27 +/- 0.17, p = 0.0006). When systolic left atrial velocities encoded as red were incorporated into the maximal jet area measurement, 7 of the 8 patients with an anterior flail leaflet had a jet area greater than 8 cm2, consistent with severe mitral regurgitation, compared with 13 of the 23 patients with a flail posterior leaflet. There was no correlation between jet area or jet area to left atrial ratio and any hemodynamic variable. Patients with acute mitral regurgitation exhibited a trend toward smaller jet areas, but this did not reach statistical significance. Regurgitant fraction calculated from pulsed Doppler recording of mitral and aortic flow was consistent with moderately severe or severe mitral regurgitation in all cases and averaged 70%. Thus, patients with a flail mitral valve leaflet have distinctive Doppler color flow findings. A highly eccentric and turbulent jet directed posteriorly to the aorta may contribute to a systematic underestimation of severe mitral regurgitation by conventional Doppler color flow criteria. The use of pulsed Doppler ultrasound to calculate regurgitant fraction in patients with a flail mitral valve leaflet may be helpful in reliably assessing the degree of mitral regurgitation.

Acute Disease↗
PubMed1990

Diastolic function in patients undergoing coronary angioplasty: influence of degree of revascularization.

To assess the early effects of successful coronary angioplasty on Doppler-derived left ventricular filling patterns and the significance of the extent of revascularization on these variables, 31 patients undergoing coronary angioplasty were examined within 24 h before and after the revascularization procedure. After angioplasty, the peak early to late velocity ratio increased from 0.89 +/- 0.2 to 1.05 +/- 0.3 (p less than 0.0001) and the one-third filling fraction increased from 42 +/- 10% to 48 +/- 10% (p less than 0.0001). The percent atrial contribution to filling decreased from 45 +/- 7% to 41 +/- 8% (p less than 0.01), and the pressure half-time and the isovolumetric relaxation time shortened from 55 +/- 15 to 43 +/- 13 ms (p less than 0.001) and from 100 +/- 14 to 82 +/- 17 ms (p less than 0.0001), respectively. When comparing patients with complete (n = 23) and incomplete (n = 8) revascularization, the same changes in the Doppler variables were observed. However, the mean rate of acceleration of early filling increased significantly after angioplasty only in those patients with complete revascularization. These data indicate that the left ventricular diastolic filling pattern is modified significantly as early as 24 h after successful coronary angioplasty. Improvement in impaired relaxation appears to be the most likely explanation for these changes, although increased myocardial stiffness in patients with incomplete revascularization is an alternative hypothesis.

Aged↗
PubMed1990

Comparison of hemodynamic pressure half-time method and Gorlin formula with Doppler and echocardiographic determinations of mitral valve area in patients with combined mitral stenosis and regurgitation.

Mitral valve area determined by the Gorlin formula in patients with combined mitral stenosis and regurgitation underestimates the true orifice size. Recent data suggest Doppler ultrasound and two-dimensional echocardiography more accurately estimate the mitral valve area in patients with mixed mitral valvular disease. This study assessed the accuracy of an alternate method, the hemodynamic pressure half-time method, for mitral valve area determination in such patients. In 22 patients, 28 separate mitral valve areas were calculated by the hemodynamic pressure half-time method, the Gorlin formula, and the Gorlin formula corrected for mitral regurgitation, and were compared with results calculated by the Doppler pressure half-time method. Six patients were studied both before and after balloon mitral valvuloplasty. In addition, mitral valve areas calculated by all four methods were compared with results obtained by planimetry in 15 patients with technically optimal echocardiograms. The mitral valve areas determined by hemodynamic pressure half-time corretated closely with the valve areas determined by Doppler (r = 0.90), whereas mitral valve areas determined by the Gorlin formula (both without and with correction for mitral regurgitation) did not correlate as well with the Doppler-estimated valve areas (r = 0.47 and r = 0.56, respectively). Correlation between the Doppler-derived mitral valve areas and the planimetered valve areas was also good (r = 0.84), as was that between the mitral valve areas calculated by hemodynamic pressure half-time and those calculated by planimetry (r = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Safety and utility of transesophageal echocardiography in the critically ill patient.

We studied the safety and utility of transesophageal echocardiography in the evaluation of critically ill patients in the intensive care unit setting. Sixty-two studies were performed in four different intensive care units on 61 patients with a mean age of 58 +/- 14 years (range 25 to 78 years). Indications for the study included suspected aortic pathologic conditions (18 patients), cardiac source of embolus (16 patients), postmyocardial infarction complications (6 patients), and suspected infective endocarditis (5 patients). Studies were performed at bedside with the use of small amounts of intravenous sedatives. The probe was passed successfully in 61 of 62 attempts. Diagnoses that were missed by surface echocardiography, including aortic dissection, left atrial thrombus, ruptured papillary muscle, and prosthetic valve vegetation were clearly identified by transesophageal echocardiography, which facilitated appropriate management in these cases. In cases in which no pathologic condition was identified, transesophageal echocardiography was useful in ruling out intracardiac shunt, in assessing left ventricular function, and in excluding significant valvular pathologic conditions. No serious complications were recorded, and the procedure was, in general, very well tolerated.

Adult↗
PubMed1990

Aortic valve decalcification.

Ultrasonic decalcification of the aortic valve was performed in 22 elderly patients with critical aortic stenosis (aortic valve areas less than 0.8 cm2) as an alternative to prosthetic valve replacement. All of the patients had symptoms. The mean New York Heart Association class was 3.3 +/- 0.9. Adequate decalcification with restoration of leaflet mobility was achieved in all patients, including seven with bicuspid aortic valves. Leaflet perforation occurred and was successfully repaired in five patients. Ten patients underwent concomitant myocardial revascularization. There were two operative deaths (9%) and three late deaths. Echocardiograms were obtained preoperatively, postoperatively, and at 6 months. The mean aortic valve area increased significantly from 0.72 +/- 0.17 to 1.42 +/- 0.31 cm2 (p less than 0.001) and the peak gradient decreased from 74 +/- 34 to 25 +/- 13 mm Hg (p less than 0.001). At 6 months the aortic valve area (1.29 +/- 0.48 cm2) and peak gradient (31 +/- 12 mm Hg) continued to be significantly better than the preoperative measurements (p less than 0.001), but the 6-month aortic valve area was slightly decreased and the gradient increased when compared with the immediate postoperative values (p less than 0.02). The prevalence of mild to moderate aortic insufficiency increased from 50% of the patients preoperatively to 87% at 6 months (p less than 0.05). Two patients subsequently required aortic valve replacement for restenosis and aortic insufficiency. Ultrasonic decalcification is effective in relieving aortic stenosis, but subsequent restenosis and insufficiency may limit its application.

Aged↗
PubMed1989

Immediate and short-term effects of aortic balloon valvuloplasty on left ventricular diastolic function and filling in humans.

The effect of aortic balloon valvuloplasty on left ventricular diastolic function and filling was investigated in 44 adult patients with severe aortic stenosis. Two-dimensional and Doppler echocardiography was performed in all patients before and 24 h after valvuloplasty. In 19 patients (short-term group) repeat studies were performed at 3 (n = 2) and 6 (n = 17) months. Left ventricular relaxation, chamber stiffness and filling were assessed in 16 patients (immediate post-valvuloplasty group) before and immediately after valvuloplasty by simultaneous micromanometer left ventricular pressure tracings and echocardiograms. Immediately after valvuloplasty, relaxation was slightly impaired in the immediate post-valvuloplasty group, as reflected by the isovolumic relaxation time constant (56 +/- 26 to 68 +/- 39 ms; p less than 0.01) and maximal negative dP/dt (2,063 +/- 640 to 1,767 +/- 495 mm Hg/s; p less than 0.001). The chamber stiffness constants and diastolic filling dynamics were unchanged immediately after valvuloplasty. Twenty-four hours after valvuloplasty, patients without mitral regurgitation (n = 24) showed increases in the peak early filling velocity (72 +/- 31 to 83 +/- 28 cm/s; p less than 0.05) and peak early to atrial filling velocity ratio (0.8 +/- 0.6 to 1.0 +/- 0.7; p less than 0.05). However, in patients with mitral regurgitation (n = 20), the diastolic filling dynamics were not significantly changed. In the short-term group at the 3 to 6 month follow-up period, patients without mitral regurgitation (n = 12) showed striking increases compared with pre-valvuloplasty values in the peak early filling velocity (66 +/- 21 to 93 +/- 31 cm/s; p less than 0.02), peak early to atrial filling velocity ratio (0.6 +/- 0.2 to 0.9 +/- 0.4; p less than 0.02) and early time-velocity integral (9 +/- 4 to 16 +/- 6 cm; p less than 0.002). In patients with mitral regurgitation (n = 7) decreases occurred in the peak early filling velocity (123 +/- 32 to 106 +/- 28 cm/s; p less than 0.05) and peak early to atrial filling velocity ratio (1.5 +/- 0.7 to 1.1 +/- 0.6; p less than 0.05). Functional class in hospital improved after valvuloplasty (3.1 +/- 1.0 to 2.6 +/- 0.9; p less than 0.001) and correlated modestly with the percent decrease in Doppler-derived peak gradient (rs = 0.41, p less than 0.02) and mean gradient (rs = 0.36, p less than 0.05), but did not correlate with changes in aortic valve area, left ventricular ejection fraction or diastolic filling variables.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1989

Exercise capacity during the first year after cardiac transplantation.

Few data are available examining the influence of perioperative clinical parameters on exercise capacity after cardiac transplantation. Accordingly, 40 patients were studied by metabolic exercise testing early (1 to 3 months) and late (6 to 12 months) after cardiac transplantation. Various clinical parameters, including congestive heart failure class, length of hospital stay, age, cold ischemic time and histologic evidence of rejection were correlated with exercise capacity after transplantation. As expected, peak exercise capacity correlated inversely with both age and length of hospital stay. There was no correlation with preoperative congestive heart failure class or heart rate at rest. Interestingly, there was a statistically significant correlation between cold ischemic time and exercise capacity after transplantation. In addition, increased episodes of rejection during the first 6 months after transplantation resulted in statistically lower exercise capacity at 6 to 12 months after the operation. Thus, ischemic damage during transport of the donor organs and subclinical damage during early rejection may affect clinical status after heart transplantation and may only be apparent during increased physical demand such as exercise.

Adult↗