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Biomedical subjects

R O Bonow

Publications and source records attributed to R O Bonow.

At least 37 records · Page 2Linked to original sources
PubMed1999

Echocardiographic prevalence of mitral and/or aortic regurgitation in patients exposed to either fenfluramine-phentermine combination or to dexfenfluramine.

We evaluated the prevalence of valvular regurgitation in patients who have taken anorectic medications. Two-dimensional echocardiograms with color flow Doppler were recorded in 200 consecutive patients referred to a major metropolitan hospital for evaluation of cardiac function because of a history of anorectic medication use. Each patient filled out a questionnaire at the time of the visit or through telephone contact. Each echocardiogram was reviewed by 2 observers. The degree of valvular regurgitation was graded by a consensus of both observers. Significant valvular regurgitation was defined as at least moderate mitral regurgitation (MR) or at least mild aortic regurgitation (AR), as recommended by the Food and Drug Administration and Centers for Disease Control and Prevention. For all patients having taken anorectic drugs, there was a 5% prevalence of at least moderate MR, a 12% prevalence of at least mild AR, and a 16% prevalence of significant MR and/or AR. Patients with significant AR and/or MR were older than those without significant valvular regurgitation (49+/-12 vs 44+/-11 years, p = 0.03). Patients with significant MR and/or AR had a longer exposure duration (8 vs 6 months, p = 0.049) to anorectic drugs. There was no difference in weight loss between those with and without significant regurgitation (p = NS). The 2 largest subgroups were patients who took the fenfluramine-phentermine combination (n = 127) and those who took dexfenfluramine alone (n = 42). The prevalence of significant MR and AR was 5% and 9% for the fenfluramine-phentermine group and 0% and 14% for the dexfenfluramine group, respectively. There was also a high subthreshold level of MR and AR in these patients.

Adult↗
PubMed1999

Prognostic implications of myocardial contractile reserve in patients with coronary artery disease and left ventricular dysfunction.

OBJECTIVES: This study was performed to assess the prognostic implications of myocardial contractile reserve (MCR) in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction. BACKGROUND: MCR during dobutamine stress echocardiography (DSE) identifies viable myocardium that may improve in function after revascularization. Whether revascularization influences prognosis of patients with MCR has not been determined. METHODS: We performed DSE in 80 patients with CAD and LV dysfunction (ejection fraction < or =40%). Viable myocardium was defined in dysfunctional myocardial segments as enhanced thickening and contraction during low-dose dobutamine (5 to 10 mcg/kg/min). Serial prospective follow-up was obtained in all patients (mean follow-up 2.2 +/- 1.1 years). RESULTS: Among 52 patients treated medically, there were 20 cardiac deaths. By multivariate analysis, the number of dysfunctional segments demonstrating MCR was the strongest predictor of survival (p < 0.03). Patients with MCR had better initial survival during medical therapy than did those without MCR, but this survival advantage was not maintained beyond three years. In contrast, survival was excellent in patients with MCR who underwent myocardial revascularization. Among 58 patients with MCR in > or =5 myocardial segments, survival at three years was 93 +/- 6% in the 24 patients who were revascularized but only 49 +/- 15% in the 34 treated medically (p < 0.02). CONCLUSIONS: Myocardial contractile reserve is a significant predictor of survival in patients with CAD and LV dysfunction undergoing medical therapy. Although patients with MCR have an initial survival advantage, this advantage is lost over the course of three years. In contrast, survival in patients with significant MCR is enhanced by revascularization.

Adult↗
PubMed1998

Contrast magnetic resonance imaging in the assessment of myocardial viability in patients with stable coronary artery disease and left ventricular dysfunction.

BACKGROUND: The utility of contrast MRI for assessing myocardial viability in stable coronary artery disease (CAD) with left ventricular dysfunction is uncertain. We therefore performed cine and contrast MRI in 24 stable patients with CAD and regional contractile abnormalities and compared MRI findings with rest-redistribution 201Tl imaging and dobutamine echocardiography. METHODS AND RESULTS: Delayed MRI contrast enhancement patterns were examined from 3 to 15 minutes after injection of 0.1 mmol/kg IV gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). Comparable MRI and 201Tl basal and midventricular short-axis images were subdivided into 6 segments. Segments judged nonviable by quantitative and qualitative assessment of 201Tl scans showed persistent, systematically greater MRI contrast signal intensity than segments judged viable (P</=0.002). Delayed contrast hyperenhancement also occurred in segments judged nonviable by dobutamine echocardiography (P</=0.03). The presence or absence of hyperenhancement correlated most closely with nonviability and viability, respectively, in segments that were akinetic or dyskinetic under resting conditions (83% concordance with 201Tl in both cases). In segments with resting hypokinesis, 58% of segments showing hyperenhancement were judged viable by 201Tl and may have represented an admixture of scar tissue and viable myocardium. CONCLUSIONS: Delayed (by 3 to 15 minutes) hyperenhancement of Gd-DTPA contrast-enhanced MRI images occurs frequently in dysfunctional areas of the left ventricle in patients with stable CAD. Hyperenhancement is associated with nonviability by rest-redistribution 201Tl scintigraphy and dobutamine echocardiography, particularly in regions exhibiting resting akinesis/dyskinesis. The absence of hyperenhancement correlates with radionuclide and echocardiographic determinations of viability, regardless of resting contractile function.

Adult↗
PubMed1998

Thallium scintigraphy compared with 18F-fluorodeoxyglucose positron emission tomography for assessing myocardial viability in patients with moderate versus severe left ventricular dysfunction.

Thallium-201 reinjection imaging and positron emission tomography provide concordant information regarding myocardial viability in many patients with coronary artery disease and left ventricular (LV) dysfunction. It is unclear whether this concordance applies to patients with severe, as well as those with moderate, LV dysfunction. We studied 44 patients with chronic coronary artery disease and LV dysfunction, subgrouped on the basis of severity of dysfunction: 23 patients had moderate and 21 had severe dysfunction (ejection fractions 34 +/- 6% and 19 +/- 6%). Patients underwent exercise thallium single-photon emission computed tomography (SPECT) with 3- to 4-hour redistribution and reinjection imaging, as well as positron emission tomography (PET) imaging with 18fluorodeoxyglucose and 15O-water. Data were analyzed quantitatively in aligned transaxial PET and SPECT tomograms. A myocardial region was considered nonviable by PET if 18fluorodeoxyglucose activity was <50% of that in a normal region, associated with proportional reduction in blood flow. Similarly, regions were considered nonviable by thallium if activity was <50% of activity in normal regions on redistribution and reinjection studies. Thallium SPECT and PET data were concordant regarding viability in 98% and 93% of myocardial regions, respectively, in patients with moderate and with severe LV dysfunction. Lower concordance was observed only when regions with severe irreversible thallium perfusion defects on redistribution images were considered in both groups: 86% and 78%, respectively (p <0.01). Thus, thallium SPECT with reinjection yields information regarding regional myocardial viability that is similar to that provided by PET in patients with severe as well as moderate LV dysfunction. However, there is discordance in >20% of regions manifesting severe irreversible thallium defects in patients with severely reduced LV function.

Aged↗
PubMed1998

Chronic aortic regurgitation. Role of medical therapy and optimal timing for surgery.

Aortic valve replacement should be performed once significant symptoms develop. Lacking important symptoms, operation should also be performed in patients with aortic regurgitation who manifest consistent and reproducible evidence of either LV contractile dysfunction at rest or extreme LV dilation. Noninvasive imaging techniques should play a major role in this evaluation. An important clinical decision, such as recommending aortic valve replacement in the asymptomatic patient, should not be based on a single echocardiographic or radionuclide angiographic measurement alone. When these data consistently indicate impaired contractile function at rest or extreme LV dilation on repeat measurements, however, operation is indicated in the asymptomatic patient. This strategy should reduce the likelihood of irreversible LV dysfunction in these patients and enhance long-term postoperative survival.

Aortic Valve Insufficiency↗