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Biomedical subjects

J A Diamond

Publications and source records attributed to J A Diamond.

At least 19 recordsLinked to original sources
PubMed2005

Abdominal diameter index: a more powerful anthropometric measure for prevalent coronary heart disease risk in adult males.

AIM: The authors wished to compare the strength of association of several anthropometric measures of body size and fat distribution among themselves and in comparison with other known risk factors for prevalent coronary heart disease (CHD). METHODS: Prevalent CHD was assessed in 466 middle-aged, male, multiracial Triborough Bridge and Tunnel Authority officers in New York City by verified history, electrocardiogram or exercise stress test. Anthropometric measures included body mass index, waist, hip and thigh circumferences, waist-hip ratio, waist-thigh ratio, sagittal abdominal diameter and abdominal diameter index (sagittal abdominal diameter/thigh circumference). Results were compared with other CHD risk factors measured simultaneously (history of diabetes, smoking, blood pressure, lipid profile, apolipoproteins A and B, lipoprotein (a), homocysteine, fibrinogen, urinary microalbumin, serum vitamin E and ferritin) and a calculated 10-year CHD risk using a Framingham algorithm (10-year Framingham CHD risk). RESULTS: CHD was found in 29 individuals. Of the six anthropometric measures, abdominal diameter index gave the largest and most significant standardized odds ratio (OR) for CHD [1.80, 95% confidence interval (CI) 1.20, 2.71], equivalent to 10-year Framingham CHD risk. Men in the highest compared with the lowest tertile of abdominal diameter index had a univariate OR of 5.47 (95% CI 1.55, 19.28) which was the only anthropometric measure that remained significant after adjusting for 10-year Framingham CHD risk. CONCLUSIONS: For middle-aged American men, abdominal diameter index may be the most powerful anthropometric measure of risk for prevalent CHD.

Abdomen↗
PubMed2005

Antihypertensive drugs and the heart.

The main goal of current antihypertensive therapy is to achieve a lowering of intra-arterial pressure by various mechanisms. A plethora of data suggests that this reduces cardiovascular morbidity and mortality due to stroke, heart failure and to a lesser extent, ischemic heart disease. Early cardiac manifestations of chronic hypertension, left ventricular hypertrophy (LVH) and diastolic dysfunction (CHF-D) confer additional risk of cardiovascular morbidity and mortality in patients with hypertension. Regression of left ventricular (LV) mass with antihypertensive therapy is associated with improved diastolic function and overall reduction in cardiovascular events, and this benefit may be independent of actual lowering of arterial pressure. Antihypertensive therapy should therefore be geared to both lower arterial blood pressure and specifically reverse pathophysiologic processes that promote LVH and CHF-D. Emerging therapies accomplish this without specifically affecting blood pressure. Therefore, future treatments for hypertension may require a combination of drugs performing complimentary tasks in lowering arterial pressure and reversing maladaptive physiologic and genetic processes causing hypertensive heart disease. This review summarizes the current and emerging approaches to the treatment of individuals with hypertensive heart disease.

Antihypertensive Agents↗
PubMed2001

Left ventricular midwall function improves with antihypertensive therapy and regression of left ventricular hypertrophy in patients with asymptomatic hypertension.

Recent evidence suggests that regression of left ventricular hypertrophy (LVH) with antihypertensive therapy improves prognosis. The mechanism for this benefit is unknown but may be related to effects on myocardial performance. Midwall fractional shortening (mFS) is often depressed in patients with asymptomatic hypertension, is associated with LVH, and is a potent, independent predictor of outcome. We therefore examined whether antihypertensive therapy may improve midwall performance. mFS as well as conventional echocardiographic parameters were measured serially among 29 hypertensive persons during 6 months of drug therapy. Stress-adjusted and absolute midwall function improved by 10% and 11%, respectively (p <0.05), whereas no significant changes were detected in other measures of chamber function. Improvement in function was more pronounced in patients with concentrically remodeled ventricular geometry and in those who achieved greater reductions in left ventricular (LV) mass. Antihypertensive therapy and LV mass regression is associated with demonstrable improvements in cardiac performance when assessed using mFS. Determinations of mFS may have a promising role in identifying patients with early hypertensive heart disease, tracking responses to therapy, and in elucidating the potential beneficial effects associated with LV mass regression.

Antihypertensive Agents↗
PubMed2001

Diastolic function in hypertension.

Diastolic dysfunction in patients with hypertension may present as asymptomatic findings on noninvasive testing, or as fulminant pulmonary edema, despite normal left ventricular systolic function. Up to 40% of hypertensive patients presenting with clinical signs of congestive heart failure have normal systolic left ventricular function. In this article we review the pathophysiologic factors affecting diastolic function in individuals with diastolic function, current and emerging tools for measuring diastolic function, and current concepts regarding the treatment of patients with diastolic congestive heart failure.

Blood Pressure↗
PubMed2001

Comparison of two calcium blockers on hemodynamics, left ventricular mass, and coronary vasodilatory in advanced hypertension.

Dihydropyridine and nondihydropyridine calcium channel blockers (CCB) differ in pharmacologic characteristics. Few clinical studies distinguish effects of CCB as monotherapy. We conducted a comprehensive comparison of two CCB on patients with moderate to severe hypertension. Thirty patients with pretreatment diastolic blood pressures > or = 100 mm Hg were randomly assigned to either nifedipine-GITS or verapamil-SR. Dose titration achieved a diastolic blood pressure of < or = 95 mm Hg or a decrease of > or = 15 mm Hg over 4 weeks. Clinic blood pressure (BP), 24-h ambulatory BP, exercise BP, left ventricular mass, systolic and diastolic function by echocardiography, and coronary flow reserve by split-dose thallium-201 imaging with adenosine were assessed at baseline, end of titration, 3 months and 6 months of treatment. Plasma renin activity, atrial natriuretic peptide, norepinephrine, and epinephrine were assayed. Both drugs caused similar reductions in clinic and 24-h ambulatory BP and similar reductions in left ventricular mass index. Compared to nifedipine-GITS, verapamil-SR produced a significantly lower resting and peak exercise heart rate. Nifedipine-GITS elicited a lower peak exercise systolic BP. At end titration nifedipine-GITS produced lower plasma atrial natriuretic peptide levels, no longer apparent by 6 months. Plasma norepinephrine was lower with verapamil-SR, also at end titration and at 3 months, but not at 6 months. Plasma epinephrine and plasma renin activity were unchanged by either drug. There was no difference for systolic or diastolic left ventricular function or coronary flow reserve between the two treatments. Once daily nifedipine-GITS and verapamil-SR are equally effective for reduction of arterial pressure in moderate to severe hypertension. Differences in their hemodynamic profiles and neurohormonal responses are consistent with preclinical pharmacologic characteristics. The clinical implications of their similarities and differences remain to be fully evaluated in outcome studies.

Blood Pressure↗
PubMed2001

Validation in the canine model of a new non-invasive method of measuring coronary blood flow reserve: split dose thallium-201 rest/stress imaging.

Diffusely impaired coronary blood flow reserve is difficult to measure non-invasively. We developed and tested a quantitative non-invasive method of measuring coronary blood flow reserve using thallium-201 perfusion imaging. Ten anesthetized dogs were injected simultaneously at rest with thallium-201 and either Ru-103 or Sn-113 microspheres. SPECT images were obtained followed by varying doses of intravenous adenosine, and a second thallium-201 dose was injected simultaneously with either Nb-95 or Sc-46 microspheres. SPECT images were then repeated. The heart was removed, sectioned and counted, along with arterial blood samples. Blood flow was calculated at rest and stress. Peak resting counts in four regions in each of three SPECT slices were subtracted from stress values and stress/rest thallium-201 count ratios (coronary flow reserve (CFR)) were calculated and correlated with the corresponding microsphere flow ratios. Overall correlation of the imaging and microsphere flow ratios was 0.77 (p = 0.0001). Regional correlation coefficients ranged from 0.65-0.86 (p = 0.0001). Coronary blood flow reserve ratios by the microsphere method ranged from 0.7 to 5.3, and by thallium-201 imaging from 0.33-2.45. The non-invasively measured coronary blood flow reserve with thallium-201 imaging and adenosine stress correlates well with microsphere-measured coronary blood flow reserve over a wide range of coronary flows, and should be useful in clinical studies of CFR impairment.

Adenosine↗
PubMed1999

Predictive value of left ventricular ejection fraction in stem cell transplantation.

We evaluated predictive value of left ventricular ejection fraction at rest (REF) and its increment with exercise (deltaEF) on autologous and allogeneic stem cell transplantation mortality. In a 7 year period, a total of 163 patients evaluated for stem cell transplantation were studied. All were followed for at least 3 months after the transplant. REF was discriminatory for peritransplant mortality only in younger (<43 years) patients (n = 66), particularly those who underwent autologous transplantation (n = 30). Resting ejection fraction was not a discriminator for early death in any other subgroup. Cardiac reserve (deltaEF) was significantly lower in patients (n = 35), who died early. The finding was most prominent in younger patients who underwent autologous transplantation (n = 26). Combination of decreased REF and low deltaEF (n = 18) was associated with high peritransplant mortality (56%), after both autologous and allogeneic transplantation. A low REF with an appropriate deltaEF (n = 43) was associated with a 19% peritransplant mortality and no deaths in the autologous group. These observations indicate that resting ejection fraction is of only limited value for pretransplant evaluation. However, measurement of cardiac reserve during exercise can provide important prognostic information before stem cell transplantation.

Adolescent↗
PubMed1999

Effect of long-term eprosartan versus enalapril antihypertensive therapy on left ventricular mass and coronary flow reserve in stage I-II hypertension. Eprosartan Study Group.

A double-blind comparator study was performed in 528 hypertensive patients [baseline sitting diastolic blood pressure (SitDBP) 95-114 mmHg]. The primary objective was to compare the incidence of drug-related cough in patients treated with enalapril and eprosartan. This paper reports the results of 27 asymptomatic patients who were recruited into a single centre substudy of the multicentre trial and randomised to receive either eprosartan (200-300 mg b.i.d.) or enalapril (5-20 mg o.d.). Blood pressure (BP) reduction, left ventricular (LV) mass regression and change in coronary flow reserve (CFR) after 6 months' treatment with either eprosartan or enalapril were compared. At the end of the study, eprosartan and enalapril were found to have caused similar reductions in BP. There was an increase in CFR in the eprosartan group to 1.6 +/- 0.3 and a decrease in CFR in the enalapril group to 1.3 +/- 0.3. Neither value was significantly different from baseline although the difference between the two groups was significant (p = 0.05). By study endpoint, there was a significant reduction in LV mass in the enalapril group (p = 0.05), but not the eprosartan (p = ns) group. Further investigation of the effects of angiotensin receptor blockers on CFR and LV mass regression appear warranted.

Acrylates↗