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Biomedical subjects

M E Brickner

Publications and source records attributed to M E Brickner.

At least 19 recordsLinked to original sources
PubMed1999

The clinical dilemma of anorectic drug use and valvular heart disease.

Recent attention has focused on reported valvular heart lesions in patients taking anorectic drugs. This editorial reviews published reports, comments on new findings from a study published in this issue of The American Journal of Cardiology, and makes clinical recommendations.

Appetite Depressants↗
PubMed1998

The Eisenmenger syndrome in adults.

For this article, the literature on the pathophysiology, clinical features, natural history, prognosis, and management of the Eisenmenger syndrome in adults was reviewed. English-language articles from 1966 to the present were identified through a search of the MEDLINE database by using the terms Eisenmenger, congenital heart disease, and pulmonary hypertension. Selected cross-referenced articles were also included. Articles on the pathophysiology, clinical presentation, evaluation, natural history, complications, and treatment of the Eisenmenger syndrome in adults were selected, and descriptive and analytical data relevant to the practicing physician were manually extracted. The Eisenmenger syndrome is characterized by elevated pulmonary vascular resistance and right-to-left shunting of blood through a systemic-to-pulmonary circulation connection. Most patients with the syndrome survive for 20 to 30 years. The hemostatic changes associated with the syndrome may lead to thromboembolic events, cerebrovascular complications, or the hyperviscosity syndrome. Erythrocytosis is present in most patients, but excessive phlebotomy may cause microcytosis and exacerbate the symptoms of hyperviscosity. Other complications associated with the Eisenmenger syndrome include hemoptysis, gout, cholelithiasis, hypertrophic osteoarthropathy, and decreased renal function. Pregnancy or noncardiac surgery is associated with a high mortality rate in patients with the Eisenmenger syndrome. Because most pediatric patients with the Eisenmenger syndrome survive to adulthood, primary care physicians should have a thorough understanding of the syndrome; its associated complications; and medical and surgical management, especially with regard to the appropriate timing of phlebotomy and lung or heart-lung transplantation. In addition, patients with the syndrome should undergo routine follow-up at a tertiary care center that has physicians and nurses with special expertise in congenital heart disease. In patients with the Eisenmenger syndrome who are pregnant or require noncardiac surgery, a multidisciplinary approach should be used to reduce the excessive mortality associated with these conditions.

Adult↗
PubMed1998

Comparison of vena contracta width by multiplane transesophageal echocardiography with quantitative Doppler assessment of mitral regurgitation.

Mitral regurgitation (MR) severity is routinely assessed by Doppler color flow mapping, which is subject to technical and hemodynamic variables. Vena contracta width may be less influenced by hemodynamic variables and has previously been shown to correlate with angiographic estimates of MR severity. This study was performed to compare mitral vena contracta width by multiplane transesophageal echocardiography (TEE) with simultaneous quantitative Doppler echocardiography in 35 patients with MR. The vena contracta width was measured at the narrowest portion of the MR jet as it emerged through the coaptation of the leaflets; it was identified in 97% of the patients. Vena contracta width correlated well with regurgitant volume (R2 = 0.81) and regurgitant orifice area (R2 = 0.81) by quantitative Doppler technique. A vena contracta width > or = 0.5 cm always predicted a regurgitant volume >60 ml and an effective regurgitant orifice area > or = 0.4 cm2 in all patients. A vena contracta width < or = 0.3 cm always predicted a regurgitant volume <45 ml and a regurgitant orifice area < or = 0.35 cm2. Thus, vena contracta width by multiplane TEE correlates well with mitral regurgitant volume and regurgitant orifice area by quantitative Doppler echocardiography and provides a simple method for the identification of patients with severe MR.

Adult↗
PubMed1998

Effects of afterload reduction on vena contracta width in mitral regurgitation.

OBJECTIVES: We used color Doppler flow mapping to determine whether vena contracta width (VCW) is a load-independent measure of the severity of mitral regurgitation. BACKGROUND: VCW has been proposed to be a relatively load-independent measure of mitral regurgitation severity in flow models using a fixed orifice. However, in patients with mitral regurgitation, VCW may not be load independent because of a dynamic regurgitant orifice. METHODS: VCW, effective regurgitant orifice area and regurgitant volume were measured by quantitative Doppler mapping in 31 patients with chronic mitral regurgitation at baseline and during nitroprusside infusion. Patients with rheumatic heart disease, annular calcification or endocarditis were considered to have a fixed regurgitant orifice, whereas patients with mitral valve prolapse, dilated cardiomyopathy or ischemia were considered to have a dynamic regurgitant orifice. RESULTS: Systolic blood pressure (148 +/- 27 to 115 +/- 25 mm Hg) and end-systolic wall stress (121 +/- 50 to 89 +/- 36) decreased with nitroprusside (p < 0.05). Although nitroprusside did not significantly change mean values for VCW (0.5 +/- 0.2 to 0.5 +/- 0.2 cm), regurgitant volume (69 +/- 47 to 69 +/- 56 ml) or effective regurgitant orifice area (0.5 +/- 0.4 to 0.5 +/- 0.6 cm2), individual patients exhibited marked directional variability. Specifically, VCW decreased in 16 patients (improved mitral regurgitation), remained unchanged in 7 patients and increased in 8 patients (worsened mitral regurgitation) with nitroprusside. Also, the VCW response to nitroprusside was concordant with changes in effective regurgitant orifice area and regurgitant volume, and was not different between dynamic and fixed orifice groups. CONCLUSIONS: Contrary to the results from in vitro studies, VCW is not load independent in patients with mitral regurgitation caused by dynamic changes in the regurgitant orifice. The origin of mitral regurgitation does not predict accurately whether the regurgitant orifice is fixed or dynamic. Finally, short-term vasodilation with nitroprusside may significantly worsen the severity of mitral regurgitation in some patients.

Adult↗
PubMed1997

Assessment of mitral regurgitation severity by Doppler color flow mapping of the vena contracta.

BACKGROUND: Although Doppler color flow mapping is widely used to assess the severity of mitral regurgitation (MR), a simple, accurate, and quantitative marker of MR by color flow mapping remains elusive. We hypothesized that vena contracta width by color flow mapping would accurately predict the severity of MR. METHODS AND RESULTS: We studied 80 patients with MR. Vena contracta width was measured in multiple views with zoom mode and nonstandard angulation to optimize its visualization. Flow volumes across the left ventricular outflow tract and mitral annulus were calculated by pulsed-Doppler technique to determine regurgitant volume. Effective regurgitant orifice area was calculated by dividing the regurgitant volume by the continuous-wave Doppler velocity-time integral of the MR jet. The cause of MR was ischemia in 24, dilated cardiomyopathy in 34 mitral valve prolapse in 12, endocarditis in 2, rheumatic disease in 2, mitral annular calcification in 1, and uncertain in 5. Regurgitant volumes ranged from 2 to 191 mL. Regurgitant orifice area ranged from 0.01 to 1.47 cm2. Single-plane vena contracta width from the parasternal long-axis view correlated well with regurgitant volume (r = .85, SEE = 20 mL) and regurgitant orifice area (r = .86, SEE = 0.15 cm2). Biplane vena contracta width from apical views correlated well with regurgitant volume (r = .85, SEE = 19 mL) and regurgitant orifice area (r = .88, SEE = 0.14 cm2). A biplane vena contracta width > or = 0.5 cm was always associated with a regurgitant volume > 60 mL and a regurgitant orifice area > 0.4 cm2. A biplane vena contracta width < or = 0.3 cm predicted a regurgitant volume < 60 mL and a regurgitant orifice area < 0.4 cm2 in 24 of 29 patients. No other parameter, including jet area, left atrial size, pulmonary flow reversal, or semiquantitative MR grade, correlated significantly with regurgitant volume or regurgitant orifice area in a multivariate analysis. CONCLUSIONS: Our results demonstrate that careful color flow mapping of the vena contracta of the MR jet provides a simple quantitative assessment of MR that correlates well with quantitative Doppler techniques.

Adult↗
PubMed1996

Cardioembolic stroke.

Cardioembolic stroke accounts for 1 out of every 5 to 6 ischemic strokes. A potential cardiac source should be considered in all patients presenting with ischemic neurologic deficits. a clear understanding of the various types of cardiac conditions associated with cardioembolic stroke is important. This article reviews potential cardiac sources of emboli and discusses the role of anticoagulation in both primary and secondary prevention of cardioembolic stroke. The role of echocardiography in evaluating patients with possible cardioembolic stroke is also addressed, and an algorithm is proposed for the use of echocardiography in evaluating patients with ischemic neurologic deficits.

Algorithms↗
PubMed1995

Dobutamine echocardiography in predicting improvement in global left ventricular systolic function after coronary bypass or angioplasty in patients with healed myocardial infarcts.

The aim of this study was to determine whether low-dose dobutamine echocardiography (DE) could predict quantitative improvement in global left ventricular (LV) systolic function after coronary revascularization. Low-dose DE was performed in 71 consecutive patients with coronary artery disease and LV dysfunction. Successful coronary bypass surgery or angioplasty was performed in 44 patients, 37 of whom had a resting echocardiogram 1 to 3 months afterward. Group A consisted of 20 patients with contractile reserve during DE, and group B consisted of 17 patients without contractile reserve. As expected, regional wall motion score index (mean +/- SD) improved in group A (1.62 +/- 0.39 to 1.38 +/- 0.31, p < 0.01) but not group B (1.56 +/- 0.42 to 1.57 +/- 0.41, p = NS). In addition, LV ejection fraction (LVEF) improved after bypass surgery or angioplasty in group A (38 +/- 5% to 42 +/- 5%, p < 0.01), but not in group B (38 +/- 7% to 39 +/- 8%, p = NS). In group A, a significant linear correlation was observed between the number of segments with contractile reserve and the improvement in LVEF (r = 0.91, p < 0.0001). A good correlation also existed between the improvement in regional wall motion score index during dobutamine infusion and the improvement in LVEF after bypass surgery or angioplasty (r = 0.90, p < 0.0001). In conclusion, low-dose DE can be used to predict quantitative improvement in global LV systolic function after coronary bypass or angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1995

Racial differences in the prevalence of left ventricular hypertrophy among chronic cocaine abusers.

There are racial differences in the prevalence and pattern of left ventricular (LV) hypertrophy in hypertension. This study was performed to determine whether racial differences also exist in LV hypertrophy among chronic cocaine users. We studied 112 chronic cocaine abusers < 45 years old in whom normal blood pressures (< or = 140/90 mm Hg) were recorded 3 times daily for 3 weeks. LV wall thickness and mass were measured echocardiographically. Technically adequate studies were obtained in 79 blacks and 33 whites. Self-reported cocaine use was higher in whites than in blacks (688 +/- 516 vs 431 +/- 468 $/week, p = 0.03). There were no group differences in terms of duration of cocaine use, age, height, weight, blood pressure, LV dimensions, or left atrial size. However, posterior wall thickness (1.13 +/- 0.17 vs 1.03 +/- 0.14 cm, p = 0.0035) and LV mass index (113 +/- 25 vs 94 +/- 19 g/m2, p = 0.0001) were significantly greater in blacks. LV hypertrophy, defined as an M-mode LV mass index > or = 134 g/m2, was present in 24 blacks (30%) and 2 whites (6%) (p = 0.011). When defined as a posterior wall thickness > or = 1.2 cm and a 2-dimensional echocardiographic LV mass index > or = 105 g/m2, LV hypertrophy was present in 37 of 79 blacks (47%) and in 6 of 33 whites (18%) (p = 0.0086). Cocaine-related LV hypertrophy is more prevalent in black men than in white men.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Multiplane transesophageal echocardiographic assessment of mitral regurgitation by Doppler color flow mapping of the vena contracta.

Assessment of the severity of mitral regurgitation (MR) by Doppler color flow mapping is limited by dependence of jet area on hemodynamic and technical variables. The width of the MR jet at its origin may be less dependent on hemodynamic variables, and thus should more accurately reflect the severity of MR. Doppler color flow mapping was performed in 80 subjects by transesophageal echocardiography (TEE) within 48 hours of catheterization. Width of the MR jet at its vena contracta was measured by both single plane and multiplane TEE and compared with the angiographic grade of MR and regurgitant volume. The width of the MR jet correlated closely with angiographic grade by both methods. A jet width > or = 6 mm identified angiographically severe MR with a sensitivity and specificity of 100% and 83% by single-plane TEE, and 95% and 98% by multiplane TEE. The sensitivity and specificity for detecting a regurgitant volume > or = 80 ml was 93% and 76% for single-plane TEE, and 86% and 95% for multiplane TEE. Thus, the width of the MR jet at its vena contracta by Doppler color flow mapping is an accurate marker of the severity of MR. By virtue of its ability to obtain orthogonal views specifically oriented to mitral leaflet coaptation, multiplane TEE is superior to single-plane TEE in assessing MR jet width.

Blood Flow Velocity↗
PubMed1994

Relation of thrombus in the left atrial appendage by transesophageal echocardiography to clinical risk factors for thrombus formation.

Transesophageal echocardiography provides excellent visualization of the left atrial appendage (LAA). This study was conducted to determine whether specific clinical risk factors could predict the presence of LAA thrombus as demonstrated by transesophageal echocardiography. The most recent 860 transesophageal echocardiographic studies performed at our institution were retrospectively reviewed. The LAA was adequately visualized in 778 patients (90%). For each study, the presence or absence of 5 specific clinical risk factors (mitral stenosis, severe left ventricular dysfunction, left atrial dilatation, atrial fibrillation, or a prosthetic mitral valve) and the presence or absence of LAA thrombi were assessed. One or more clinical risk factors were present in 149 patients, whereas no defined risk factors were noted in 629. Left atrial appendage thrombi were found in 20 of 149 patients with versus 6 of 629 patients without a clinical risk factor (13% vs 1%, p = 0.0001). By logistic regression analysis, mitral stenosis, severe left ventricular dysfunction, and left atrial dilatation were independent risk factors for LAA thrombus formation. Neither atrial fibrillation nor the presence of a mitral prosthetic valve achieved statistical significance as independent risk factors for LAA thrombus. Thus, LAA thrombi occur most often in patients with risk factors for thrombus formation that can be determined by clinical evaluation and transthoracic echocardiography. Transesophageal echocardiography rarely identifies LAA thrombi in patients without such clinical risk factors.

Chi-Square Distribution↗
PubMed1993

Dobutamine stress echocardiography identifies hibernating myocardium and predicts recovery of left ventricular function after coronary revascularization.

BACKGROUND: The identification of hibernating myocardium is important in selecting patients who will benefit from coronary revascularization. This study was performed to determine whether dobutamine stress echocardiography (DSE) could identify hibernating myocardium and predict improvement in regional systolic wall thickening after revascularization. METHODS AND RESULTS: DSE was performed in 49 consecutive patients with multivessel coronary disease and depressed left ventricular function. Contractile reverse during DSE was defined by the presence of two criteria: (1) improved systolic wall thickening in at least two adjacent abnormal segments and (2) > or = 20% improvement in regional wall thickening score. Postoperative echocardiograms were evaluated for improved regional wall thickening in 25 patients at least 4 weeks after successful coronary revascularization. All studies were read in blinded fashion. Contractile reserve during DSE was present in 24 (49%) of 49 patients. The presence or absence of contractile reserve on preoperative DSE predicted recovery of ventricular function in the 25 patients who underwent successful revascularization. Thus, 9 of 11 patients with contractile reserve had improved systolic wall thickening after revascularization (hibernating myocardium), whereas 12 of 14 patients without contractile reserve did not improve (P = .003). CONCLUSIONS: Dobutamine stress echocardiography provides a simple, cost-effective, and widely available method of identifying hibernating myocardium and predicting improvement in regional left ventricular wall thickening after coronary revascularization. This technique may be clinically valuable in the selection of patients for coronary revascularization.

Adult↗
PubMed1992

Intravascular ultrasound imaging of saphenous vein grafts in vitro: comparison with histologic and quantitative angiographic findings.

The ubiquity of coronary artery disease and the resultant widespread use of saphenous veins for coronary artery bypass surgery has stimulated considerable interest in the morphologic and pathophysiologic alterations these vessels undergo after implantation. This study was undertaken to determine the ability of intravascular ultrasound to identify and characterize abnormalities in saphenous vein grafts. Ten saphenous vein grafts excised at autopsy and nine saphenous vein segments harvested during coronary artery bypass surgery were examined with intravascular ultrasound imaging, quantitative coronary angiographic techniques and histologic analysis. Intravascular ultrasound lumen measurements were strongly correlated with quantitative coronary arteriographic measurements (r 0.91, SEE 0.5 mm). Wall thickness was significantly greater in the vein grafts after long-term implantation than in the freshly harvested veins (average thickness 1.4 +/- 0.5 vs. 0.7 +/- 0.2 mm, p less than 0.007); this finding correlated histologically with vein wall fibrosis. There was good correlation between ultrasound imaging and histologic analysis, with the ability to distinguish among normal intima, intimal hyperplasia, vein wall fibrosis and atheromatous plaque. Thus, this preliminary study demonstrates the ability of intravascular ultrasound to provide real-time cross-sectional images of saphenous veins and morphologic characterization of their walls. This modality may have important clinical applications, including the ability to detect serial changes in vein graft intimal hyperplasia and atherosclerosis.

Arteriosclerosis↗
PubMed1992

Improved left ventricular contractility with cool temperature hemodialysis.

Cool temperature dialysis (CTD) has been shown to sharply decrease the frequency of intradialytic hemodialysis hypotension, but the mechanism of this hemodynamic protection is unknown. Therefore, we performed two-dimensional echocardiographic studies of left ventricular contractility in six stable hemodialysis patients before and after hemodialysis at 37 degrees C (RTD) and 35 degrees C (CTD). Left ventricular function was assessed by plotting the rate-corrected velocity of circumferential fiber shortening (Vcfc) against end-systolic wall stress (sigma es) at four different levels of afterload. Linear regression was used to calculate Vcfc at a common afterload of 50 g/cm2. Changes in weight and dialysis parameters were similar following RTD and CTD. Mean arterial pressure and heart rate did not change significantly following RTD or CTD. The Vcfc - sigma es relation was shifted upward in each patient after CTD, indicating increased contractility as compared to RTD or pre-dialysis baseline. Pre-dialysis Vcfc at an afterload of 50 g/cm2 was similar during RTD and CTD (0.94 +/- 0.24 circ/sec vs. 0.92 +/- 0.22 circ/sec). Postdialysis Vcfc at an afterload of 50 g/cm2 was significantly higher for CTD than for RTD (1.13 +/- 0.29 circ/sec vs. 0.98 +/- 0.30 circ/sec, P = 0.0004). Thus, cool temperature dialysis increases left ventricular contractility in hemodialysis patients, which may be a potential mechanism whereby hemodynamic tolerance to the dialysis procedure is improved.

Adult↗