PubMed Health⌕ Search

Biomedical subjects

J B Kostis

Publications and source records attributed to J B Kostis.

At least 19 recordsLinked to original sources
PubMed1994

The effect of chlorthalidone on ventricular ectopic activity in patients with isolated systolic hypertension. The SHEP Study Group.

In an ancillary study of the Systolic Hypertension in the Elderly Program (SHEP), the effects of diuretics on ventricular ectopic activity were investigated in 186 patients with isolated systolic hypertension. Ventricular premature complexes (VPCs) were examined as the number of VPCs/24 hours, presence of > or = 1 VPC, presence of > or = 10 VPCs/24 hours, and presence of VPC pairs or ventricular tachycardia. Significant changes in VPCs were not observed either in the 92 patients randomized to chlorthalidone stepped-care (12.5 and 25 mg/day) or in the 94 placebo-treated patients (p > 0.1 for all VPC definitions and both groups). Serum potassium decreased from 4.4 +/- 0.5 to 4.1 +/- 0.5 mEq/liter (p = 0.002) in the chlorthalidone group and did not change (4.4 +/- 0.5 to 4.5 +/- 0.4 mEq/liter) in the placebo group. Potassium was prescribed routinely for confirmed hypokalemia < 3.5 mEq/liter. A relation between serum potassium and VPC or change in serum potassium and change in VPC was not observed in the chlorthalidone group. In summary, in patients with isolated systolic hypertension, chlorthalidone in doses that are effective in decreasing stroke and cardiovascular event rates (12.5 or 25 mg/day), did not increase VPCs.

Aged↗
PubMed1994

Correlates of ventricular ectopic activity in isolated systolic hypertension. SHEP Cooperative Research Group.

Ventricular ectopic activity was recorded at baseline in 5.6% of the 12-lead electrocardiograms and 8.2% of the 2-minute rhythm strips of 4674 subjects with isolated systolic hypertension (systolic blood pressure 160 to 219 mm Hg, diastolic blood pressure < 90 mm Hg) participating in the Systolic Hypertension in the Elderly Program (SHEP). In this study 1.3% had 6 to 10 ventricular premature beats (VPB), and 0.7% had > 10 VPB on the 2-minute rhythm strip. Correlates of VPB presence on the 12-lead ECG were older-age male sex, presence of Q/QS pattern and higher heart rate. Participants with serum potassium < 3.5 mmol/L had a higher prevalence of VPB. Similarly, the number of VPB on the 2-minute rhythm strip was associated with male sex, increasing age, with lower serum potassium, history of palpitations, and presence of Q/QS patterns.

Aged↗
PubMed1992

The effect of treatment on survival in congestive heart failure.

Congestive heart failure (CHF) is a disorder characterized by a variety of clinical, biochemical, electrophysiological, and hemodynamic abnormalities. During the past two decades, numerous drugs have been employed in the treatment of this complex syndrome, and many agents have been shown to improve symptoms and ventricular function in patients with CHF. Because CHF is associated with a high risk of death, treatment should be directed not only toward the relief of symptoms, but also toward a reduction in mortality. Many variables have been shown to be related to survival; taken individually, however, each is limited in its utility in predicting prognosis. In recent years, large-scale studies with large sample sizes have directly assessed the effects of treatment on mortality in CHF. Results from these trials indicate that vasodilators and angiotensin-converting enzyme (ACE) inhibitors may improve mortality in patients with symptoms of heart failure. Additional trials are now in progress to evaluate the effect of treatment on patients with asymptomatic left ventricular dysfunction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Arterial blood nicotine concentration and coronary vasoconstrictive effect of low-nicotine cigarette smoking.

Low-nicotine cigarettes have been advertised to the public as less harmful to the cardiovascular system. We studied the effects of smoking two low-nicotine cigarettes on arterial and venous blood nicotine levels, hemodynamics, and coronary vascular tone in 12 patients referred for diagnostic coronary arteriography. All were chronic smokers as evidenced by their elevated baseline arterial and venous cotinine blood levels (139 +/- 30 ng/ml and 155 +/- 34 ng/ml, respectively). High-resolution coronary angiograms were evaluated "blindly" before and after smoking. An electronic caliper was used to measure the diameter of disease-free coronary segments of the left anterior descending and circumflex arteries. Arterial nicotine levels rose from 5 +/- 1 ng/ml at baseline to 37 +/- 7 ng/ml (p less than 0.01) after the first cigarette was smoked and to 45 +/- 8 ng/ml (p less than 0.01) after the second cigarette. Venous nicotine levels rose from 8 +/- 2 ng at baseline to 15 +/- 3 ng/ml (p less than 0.05) after the first cigarette and to 20 +/- 3 ng/ml (p less than 0.01) after the second cigarette. After the first cigarette heart rate increased 8 +/- 2 beats/min (p less than 0.003) and double product 1229 +/- 400 beats/min x mm Hg (p less than 0.02). Compared to baseline values, after the second cigarette heart rate increased 9 +/- 1 beats/min (p less than 0.001) and double product 1767 +/- 486 beats/min x mm Hg (p less than 0.01). Systolic, diastolic, and mean blood pressure did not change significantly after either the first or second cigarette.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1992

Superiority of nonpharmacologic therapy compared to propranolol and placebo in men with mild hypertension: a randomized, prospective trial.

We compared the effects of nonpharmacologic therapy, propranolol monotherapy, and placebo on blood pressure, metabolic, exercise, and quality of life variables in a 12-week, randomized, placebo-controlled trial of 79 male patients with hypertension. A significant reduction in diastolic blood pressure was observed with both nondrug therapy (-8.0 +/- 1.08 mm Hg) and propranolol (-9.5 +/- 1.46 mm Hg) compared to placebo (-0.1 +/- 2.01 mm Hg). However, only patients receiving nonpharmacologic therapy showed a reduced body mass index, lower total and low-density lipoprotein serum cholesterol levels, and increased exercise tolerance compared to both propranolol and placebo. Patients receiving propranolol felt less anxious and unsure but showed a significant decrement in nocturnal penile tumescence compared to both placebo and nondrug therapy. Patients receiving nondrug therapy felt more energetic and reported improved sexual arousal and greater sexual satisfaction after treatment. Reductions in blood pressure in the nondrug treatment group were related to both weight reduction and improved fitness. We conclude that nondrug therapy is effective in controlling blood pressure in men with mild hypertension and is associated with improvements in weight, lipoprotein levels, and exercise tolerance compared to both propranolol and placebo. Quality of life assessments further support the use of nondrug therapy in this context.

Diet, Reducing↗
PubMed1992

Application of adaptive filters to noninvasive acoustical detection of coronary occlusions before and after angioplasty.

Previous studies have indicated that coronary stenoses produce sounds due to the turbulent blood flow in these vessels [1]-[10]. Measurement of these signals forms the basis of our noninvasive approach to the detection of coronary artery disease. It is during diastole that coronary blood flow is maximum and the sounds associated with turbulent blood flow through partially occluded coronary arteries would be loudest [1]-[10]. Isolated diastolic heart sounds taken from recordings made at the patient's bedside were modeled using the autoregressive (AR) and autoregressive moving average (ARMA) methods [4], [7] after adaptive line enhancement (ALE). Decisions were made in a blind fashion without prior knowledge of whether a given recording was made before or after angioplasty. Resulting model frequency spectra showed greater high-frequency components (between 400 and 800 Hz) in preangioplasty patients, and a consistent shift in amplitude of the second pole pairs of the AR and ARMA methods with surgery. Blind assessment, based on frequency spectra and poles, correctly classified the diastolic recordings in 18 of 20 cases. These results provide strong evidence supporting our hypothesis that coronary stenoses produce detectable sounds during diastole [1]-[10].

Angioplasty, Balloon, Coronary↗
PubMed1992

Differential exercise effects of captopril and nadolol in patients with essential hypertension.

In a crossover study, 12 patients with mild to moderate hypertension were given placebo, captopril (12.5 to 50 mg three times a day), and nadolol (20 to 160 mg once a day) to control the resting diastolic blood pressure to a nearly identical degree (p less than 0.0001) (106.1 +/- 4 placebo, 89.6 +/- 8 captopril, 89.8 +/- 7 nadolol). Both drugs lowered (p less than 0.0004) systolic and diastolic blood pressure at rest and during exercise. However, systolic blood pressure lowering during exercise was more pronounced (p less than 0.05) with nadolol than with captopril (difference of 6 mmHg, 16 mmHg, and 21 mmHg at 5.0, 7.0, and 9.0 metabolic equivalents (METS) respectively). Heart rate was lower (p less than 0.05) at rest and during exercise with nadolol as compared with placebo and with captopril. These data imply different mechanisms of action of the two drugs at rest and during exercise and may help in selection of drug therapy in special patient subsets.

Adult↗
PubMed1992

The prognostic significance of very low frequency ventricular ectopic activity in survivors of acute myocardial infarction. BHAT Study Group.

Survivors of myocardial infarction with less than 2 PVC/h on 24-h ambulatory electrocardiography were followed up for an average of 25 months (11 to 40 months) while receiving a placebo (1,222 patients) or propranolol, 180 or 240 mg/day (1,234 patients). Three quarters of the participants with PVCs had an average of less than 2 PVC/h. Only 16 percent did not have any ventricular ectopic activity during the 24 h. Analysis of total mortality according to the number of premature ventricular complexes per hour showed that patients who had PVCs with a very low frequency (less than 0.5/h) had 49 percent higher mortality than patients who did not have any PVC. Patients who had greater than 0.5 PVC/h but less than 1 PVC/h had a statistically significant higher mortality rate, 11.7 vs 4.1 percent (p less than 0.0001) than patients who had no PVC. These data indicate that low ventricular ectopic activity frequency is associated with increased mortality in survivors of acute myocardial infarction.

Cardiac Complexes, Premature↗
PubMed1992

Twenty-four hour blood pressure effect of once-daily lisinopril, enalapril, and placebo in patients with mild to moderate hypertension.

This multicentre, double-blind, parallel-group, placebo-controlled study compared the antihypertensive effects of equal doses of two long-acting angiotensin converting enzyme (ACE) inhibitors. After a two-week, placebo run-in phase, 110 patients with mild to moderate hypertension were randomised to receive 10 mg lisinopril or enalapril, or placebo for 4 weeks. Office BPs were measured at regular intervals throughout the study. Twenty-four hour ambulatory blood pressure (ABP) was measured at baseline and after the first and final doses of study drug. Serum ACE activity and aldosterone were obtained concomitantly with each ABP monitoring. Office BP differences from placebo reached (P less than 0.05) or approached (P less than 0.10) statistical significance at all observations for the lisinopril group but were not significant for any observation in the enalapril group and approached significance on two occasions. After four weeks of treatment, ABP analysis revealed that the lisinopril and enalapril groups, when compared with placebo, had similar and significant systolic and diastolic AUC reductions (P less than 0.01) from baseline over the 24 h dosing interval. During the second half of the dosing interval, 13-24 h post drug administration, the lisinopril group was significantly different from placebo (systolic BP, P = 0.002; diastolic BP, P = 0.005) while the enalapril group was not. Both drugs were well tolerated. The results indicate that monotherapy with 10 mg of lisinopril is as effective as with 10 mg of enalapril, and that ABP monitoring is useful in more precisely depicting the clinical effect of the known pharmacokinetic properties of these two agents.

Adult↗
PubMed1991

Beta blocker effects on heart rate during sleep: a placebo-controlled polysomnographic study with normotensive males.

Although the effect of beta blockers on heart rate (HR) at rest, during exercise, and by ambulatory electrocardiography during the day and night has been studied extensively, data on the effect of these drugs on heart rate during the various stages of sleep are not available. We performed overnight polysomnography and exercise testing in a randomized, double-blind, placebo-controlled, Latin square crossover study of four beta blockers with different ancillary properties (atenolol 100 mg daily, metoprolol 100 mg, pindolol 10 mg, and propranolol 80 mg), on 30 healthy men aged 23-40 years (29.4 +/- 4.3) (mean +/- SD). At rest pindolol increased HR by 4.7 beats/min +/- 13.1 (p less than 0.05), while beta blockers without intrinsic sympathomimetic activity (ISA) decreased HR (p less than 0.0001) by 6.1 +/- 8.8 (atenolol), 5.8 +/- 8.4 (propranolol), and 5.0 +/- 9.4 (metoprolol). Exercise at 125 W increased HR on placebo by 76.4 +/- 18.4 beats. Compared to placebo all beta blockers were associated with lower (p less than 0.0001) exercise HR by 18.3 +/- 23.2 atenolol, 21.1 +/- 15.5 metoprolol, 16.8 +/- 14.1 pindolol, and 20.8 +/- 13.1 propranolol [not significant (NS) among beta blockers]. Thus the effect of beta blockers on heart rate was magnified during exercise. Mean and maximum HR were higher in rapid eye movement (REM) than in nonREM (NREM) sleep (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1991

Noninvasive estimation of cardiac output.

A noninvasive method of measuring cardiac output is described. The method uses adaptive aorta models in conjunction with femoral and carotid pulse contour waveform measurements to calculate aortic flow. Results are presented from measurements on dogs using internal pressure recordings made with fluid-filled catheters and compared with electromagnetic flow measurements taken in the ascending aorta. Preliminary results using external pulse measurements on patients are also presented and compared with thermal dilution measurements.

Animals↗
PubMed1991

The use of magnetic resonance imaging in the study of edema.

A method of studying edema using magnetic resonance imaging (MRI) is presented. Three patients with lower extremity edema due to congestive heart failure were imaged with a 0.6 tesla system before and after diuresis. Edge detection algorithms were utilized to precisely outline regions of interest for quantification. Water and nonwater elements were separated within the region of interest to quantify water content. The results show that: (1) Edema can be quantified by use of MRI. (2) Subcutaneous edema is distributed along defined planes (ie, nonuniformly). (3) Increased water content is present not only in the subcutaneous tissue but also in deeper lying muscle.

Algorithms↗