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Biomedical subjects

A A Carr

Publications and source records attributed to A A Carr.

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

Racial aspects of ambulatory blood pressure.

Ambulatory blood pressure measurements, recorded by a Del Mar Pressurometer IV, were performed in 71 patients (25 blacks and 46 whites) with documented essential hypertension (supine diastolic blood pressure 95-119 mmHg) after four weeks of placebo treatment. Each 24-hour ambulatory BP measurement was calibrated with manual measurements within 5 mmHg and was repeated according to the daily conditions (work status) of the original recording. Ambulatory BP measurements were recorded every 15 minutes over 24 hours on two separate occasions one week apart. The mean of two 24-hour measurements was the value for the individual patient. Analyses of variance indicated no significant difference in the mean age, height, weight, 24-hour ambulatory systolic or diastolic BP, 8 am to 12 noon systolic or diastolic ambulatory BP, or 12 midnight to 4 am ambulatory systolic or diastolic BP for blacks versus whites. Among the subset of females, the 20 blacks were older than the 23 whites. Despite this age difference, there was no significant difference in height, weight or 24-hour, 8 am to 12 noon, or 12 midnight to 4 am ambulatory BP measurements. Therefore, this study does not support a racial difference in the level of ambulatory blood pressure measurement in these hypertensive patients.

Ambulatory Care↗
PubMed1991

Nifedipine GITS (gastrointestinal therapeutic system) bezoar.

In a patient with a gastroplasty, gastric outlet obstruction developed after the dosage of nifedipine GITS (gastrointestinal therapeutic system) was increased from 30 to 60 mg/d. The hard, insoluble shell for this extended-release tablet appears causative.

Adult↗
PubMed1990

Multicenter evaluation of the hemodynamic effects of bisoprolol in patients with mild to moderate hypertension.

Twenty-six patients with mild-to-moderate essential hypertension participated in a 6-week outpatient, multicenter, randomized, double-blind, placebo-controlled two-way crossover study to assess the hemodynamic effects of bisoprolol (20 mg QD) at steady state. Hemodynamic assessments included sitting blood pressure, heart rate, and left-ventricular ejection fraction by radionuclide ventriculography after 7 days of bisoprolol or placebo at trough (24 h post-dose) and peak (3 h post-dose) values. The group adjusted mean ejection fraction was not significantly different in patients receiving bisoprolol compared with the placebo group at either peak or trough measurements; in fact, means in patients taking bisoprolol were slightly higher than in the placebo group. No symptomatic hypotension was documented. Blood pressure, measured 24 hours after dosing, was significantly lower in those receiving bisoprolol when compared with the placebo group, by 7.7 mm Hg and 9 mm Hg for diastolic and systolic blood pressure, respectively. Similarly, mean values of heart rate were 10 beats/min lower in the bisoprolol patients than in the placebo group. Only headache and insomnia occurred as adverse events. Bisoprolol (20 mg QD) effectively lowered blood pressure over a 24-hour period without significantly reducing ejection fraction or causing adverse clinical or biochemical events.

Adrenergic beta-Antagonists↗
PubMed1990

Biochemical, endocrine, and mineral effects of indapamide in black women.

Black women with established essential hypertension, without renal insufficiency or diabetes mellitus, were withdrawn from their usual antihypertensive therapy for 2-3 weeks prior to entry into a study to evaluate pertinent biochemical and mineral effects of indapamide treatment. Twenty patients with a sitting diastolic blood pressure greater than 90 mm Hg had baseline measurements of plasma total cholesterol, HDL cholesterol, triglycerides, glucose, uric acid, potassium, magnesium, calcium, selenium, renin, norepinephrine, whole blood ionized calcium, and glycosylated hemoglobin. Low-density lipoprotein (LDL) cholesterol was calculated by the Friedewald equation. The patients were placed on a fixed daily dose of 2.5 mg indapamide. Blood pressure and blood tests were repeated at 4, 8, and 12 weeks of treatment. The systolic and diastolic blood pressure were both lowered significantly at week 12. Plasma renin activity was significantly increased. There was no significant change in norepinephrine, glucose, glycosylated hemoglobin, uric acid, ionized calcium, calcium, triglycerides, potassium, magnesium, or selenium. Total cholesterol increased with an increase in both high-density lipoprotein (HDL) and LDL cholesterol; however, these increases did not alter significantly either the total/HDL cholesterol or LDL/HDL cholesterol ratios. It is concluded that 2.5 mg of indapamide per day effectively lowers blood pressure with no significant adverse metabolic effects.

Adult↗
PubMed1990

Placebo-controlled trial of once-a-day isradipine monotherapy in mild to moderately severe hypertension.

The efficacy and safety of once-daily dosing of isradipine, a new calcium antagonist vasodilator, was evaluated in a multicenter, placebo-controlled trial in hypertensive patients who had supine diastolic blood pressure (SDBP) 100-119 mm Hg. After a 3-week single-blind placebo washout patients randomly received either isradipine, 5 mg once daily, or a matching placebo; if SDBP remained greater than or equal to 95 mm Hg or less than or equal to 10 mm Hg below baseline at four weekly clinic visits, isradipine was increased at weekly intervals by 5 mg once daily up to 20 mg and maintained during weeks 5 and 6. At week 6 mean supine blood pressure 24 hours after dosing had declined from 163 +/- 20/105 +/- 5 (N = 78) to 146 +/- 17/92 +/- 7 mm Hg (N = 60) on isradipine, 14.5 mg once daily, and from 163 +/- 20/105 +/- 6 (N = 85) to 157 +/- 18/99 +/- 10 mm Hg (N = 64) on placebo (P less than .001 between groups). Standing blood pressure decreased from 159 +/- 20/104 +/- 8 to 144 +/- 18/93 +/- 11 mm Hg with isradipine and from 160 +/- 22/105 +/- 9 to 154 +/- 19/101 +/- 11 mm Hg with placebo (P less than .001 between groups) without signs or symptoms of postural hypotension. A SDBP less than or equal to 90 mm Hg or a greater than or equal to 10 mm Hg fall below baseline was achieved in 41 of 78 isradipine-treated (53%) and 18 of 85 placebo-treated subjects (21%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1990

Relations among impaired coronary flow reserve, left ventricular hypertrophy and thallium perfusion defects in hypertensive patients without obstructive coronary artery disease.

Invasive Doppler catheter-derived coronary flow reserve, echocardiographic measurements of left ventricular hypertrophy and intravenous dipyridamole-limited stress thallium-201 scintigraphy were compared in 48 patients (40 were hypertensive or diabetic) with clinical ischemic heart disease and no or minor coronary artery disease. Abnormal vasodilator reserve (ratio less than 3:1) occurred in 50% of the study group and markedly abnormal reserve (less than or equal to 2:1) occurred in 27%. Coronary vasodilator reserve was significantly lower (2.2 +/- 0.8 versus 3.5 +/- 1.3, p = 0.003) and indexed left ventricular mass significantly higher (152.6 +/- 42.2 versus 113.6 +/- 24.0 g, p = 0.0007) in patients with a positive (n = 11) versus a negative (n = 32) thallium perfusion scan. Coronary flow reserve was linearly related in coronary basal flow velocity as follows: y = -0.17x + 4.59; r = -0.57; p = 0.00002. The decrement in flow reserve was not linearly related to the degree of left ventricular hypertrophy. Abnormal vasodilator reserve subsets found in hypertensive patients were defined on the basis of basal flow velocity, indexed left ventricular mass and clinical factors. In this series, diabetes did not cause a detectable additional decrement in flow reserve above that found with hypertension alone. These findings demonstrate that thallium perfusion defects are associated with depressed coronary vasodilator reserve in hypertensive patients without obstructive coronary artery disease. Left ventricular hypertrophy by indexed mass criteria is predictive of which hypertensive patients are likely to have thallium defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1990

The new calcium antagonist isradipine. Effect on blood pressure and the left ventricle in black hypertensive patients.

Treatment with the new calcium antagonist isradipine significantly reduced diastolic blood pressure to less than 90 mm Hg in 64% of fourteen blacks with mild or moderately severe essential hypertension. There was a significant reduction in the echocardiographic measures of left ventricular wall thickness and mass in these patients. There was also an increase in fractional left ventricular mass index, shortening and ejection fraction per 100 g left ventricular mass and no indication in mean circumferential shortening. There was another indication of improved left ventricular performance. With the reduced left ventricular mass and diastolic blood pressure, there was a reduction in the ratio of peak systolic wall stress to fractional shortening per 100 g left ventricular mass. There was a significant relationship between peak systolic wall stress and fractional shortening per 100 g left ventricular mass index. The directional change after left ventricular mass reduction with isradipine indicated improved left ventricular function. There was an increase in left ventricular wall thickness and mass both in those patients not controlled on isradipine combined with those treated with placebo (n = 10), and in those treated with placebo (n = 5) there was an increase in wall thickness. These changes occurred in five weeks. There was no regression to a lower mean of left ventricular mass or wall thickness during placebo. There was reduction in electrocardiogram (ECG) ST-T changes of ischemia in those patients with diastolic blood pressure reduced to less than 90 mm Hg. Isradipine monotherapy was an effective antihypertensive drug in blacks with essential hypertension, resulting in regression of left ventricular wall thickness and mass and augmentation of fractional shortening per 100 g left ventricular mass.

Antihypertensive Agents↗
PubMed1990

Ambulatory blood pressure monitoring and echocardiographic left ventricular wall thickness and mass.

In a highly select group of stable hypertensive patients, we have assessed the strength of association between various blood pressure measurements (24 h average automated ambulatory blood pressure, 4 h automated ambulatory morning average blood pressure, multiple office visit average blood pressure, and a single office visit average blood pressure) and various echocardiographic indices of hypertensive cardiac target organ damage (left atrial diameter, left ventricular end diastolic diameter, posterior wall thickness, combined wall thickness, relative wall thickness, left ventricular mass and mass index, and combined wall thickness/left ventricular diastolic diameter ratio). These data demonstrated that a single 24 h average diastolic blood pressure by automatic noninvasive ambulatory monitoring was a significantly better predictor of echocardiographic posterior wall thickness, combined wall thickness or relative wall thickness than the multiple office or single office average diastolic blood pressure. Also there were highly significant correlations between both 24 h average systolic and diastolic blood pressure and these echocardiographic parameters (in descending order of correlation coefficient): combined wall thickness, posterior wall thickness, combined wall thickness/left ventricular diastolic diameter, left ventricular mass index, relative wall thickness, and left ventricular mass. Left ventricular end diastolic dimension did not linearly correlate with any systolic or diastolic blood pressure measurement. Left atrial dimension demonstrated only a significant association with 24 h average diastolic blood pressure. Single office average blood pressure did not linearly correlate with any echocardiographic parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The calcium antagonist isradipine and its effect on blood pressure related to plasma renin activity.

This study was designed to test the hypothesis that peripheral vein plasma renin activity is a determinant of the magnitude of the hypotensive effect of the calcium antagonist Isradipine when given to mild to moderately severe essential hypertensives. There was significant relationship between plasma renin activity and blood pressure reduction by Isradipine. The lower the plasma renin activity the greater the blood pressure reduction. Both plasma volume and initial diastolic blood pressure level were not determinants. Thus, low peripheral vein plasma renin activity is a determinant (marker) of the hypotensive effect of Isradipine in mild to moderately severe uncomplicated essential hypertensives.

Adult↗
PubMed1990

Effects of MDL 11,939 on action potential and contractile force in cardiac tissues: a comparison with bretylium, clofilium, and sotalol.

The effect of MDL 11,939 hydrochloride [alpha-phenyl-1-(2-phenylethyl)-4-piperidinemethanol HCl], a novel antiarrhythmic agent, was studied using microelectrode recording techniques. MDL 11,939 (10(-7) - 10(-6) M increased the action potential (AP) duration in both guinea pig papillary muscle and dog Purkinje fiber with a maximum effective concentration of 10(-6) to 3 x 10(-6) M. MDL 11,939 up to and including 10(-6) M did not alter upstroke velocity (Vmax) of the AP in either tissue but 10(-5) M decreased the Vmax in Purkinje fibers. Compared to the other class III antiarrhythmic agents (bretylium, clofilium, and d-sotalol), MDL 11,939 was among the most potent in increasing AP duration in the papillary muscle, while being relatively less effective in increasing AP duration in Purkinje fiber. Bretylium did not increase the AP duration in papillary muscle unless it was reserpinized. MDL 11,939, clofilium, and d-sotalol all produced negative inotropic effects in papillary muscle, whereas bretylium produced a positive inotropic effect. The positive inotropic effect of bretylium was abolished by reserpinization. In papillary muscle preparations depolarized with 22 mM K+, MDL 11,939 at concentrations greater than or equal to 10(-5) M depressed Vmax of the slow AP, suggesting that it inhibited the inward Ca2+ current, and such an effect may contribute to the negative inotropic effect of this agent. In the depolarized preparations, the slow AP duration was still increased by concentrations of MDL 11,939 greater than or equal to 10(-6) M. In conclusion, MDL 11,939 has cellular electrophysiological properties that suggest a class III antiarrhythmic activity.

Action Potentials↗
PubMed1989

Efficacy and safety of isradipine in hypertension.

Of the calcium channel blocking drugs, only verapamil is approved in the United States for treatment of hypertension. Isradipine is a 1,4-dihydropyridine calcium blocker that may be given on a twice-daily basis. It causes peripheral vasodilation with minimal cardiodepressant activity. We undertook a double-blind, parallel group randomized, multicenter study of 203 hypertensive subjects to examine the efficacy and safety of isradipine in treatment of hypertension. Subjects were given 0, 2.5, 5, 7.5, or 10 mg isradipine twice daily for up to 5 weeks. There was a significant dose-response relationship between isradipine dose and decrease in systolic blood pressure (SBP) and diastolic blood pressure (DBP). Isradipine 15 mg/day reduced supine pressure by 16/15 mm Hg in patients with starting DBP less than 105 mm Hg and by 38/22 mm Hg in those with starting DBP greater than or equal to 105 mm Hg. There was no significant orthostatic fall in blood pressure at any dose. Heart rate (HR) increased on an average by only a maximum of four beats/min. The drug was slightly more effective in the elderly in the standing position than in the young in the standing position. Adverse effects were mild, and only six patients were discontinued from the study because of adverse effects. Isradipine appears to be a safe, effective drug in monotherapy of hypertension at a wide range of patient ages.

Adolescent↗
PubMed1989

Isradipine vs propranolol in hydrochlorothiazide-treated hypertensives. A multicenter evaluation.

A randomized, parallel, controlled study was conducted to evaluate the safety and efficacy of isradipine, 2.5 to 10 mg orally twice a day, compared with propranolol hydrochloride, 60 to 240 mg orally twice a day, in 78 hypertensives whose supine diastolic blood pressure was greater than 95 mm Hg while receiving 50 mg/d or more of hydrochlorothiazide. Isradipine or propranolol was titrated during a 10-week double-blind phase to achieve a supine diastolic blood pressure below 90 mm Hg while a fixed dose of hydrochlorothiazide was maintained. Supine diastolic blood pressure was reduced by 10 mm Hg in 88% of the isradipine/hydrochlorothiazide-treated and 83% of the propranolol/hydrochlorothiazide-treated groups and to less than 90 mm Hg in 55% of the isradipine/hydrochlorothiazide-treated and 69% of the propranolol/hydrochlorothiazide-treated patients. There was no significant difference in supine blood pressure reduction between either group, but there was a 3-to 4-beats per minute increase in supine heart rate in isradipine-treated patients and an expected 15- to 20-beats per minute decrease in heart rate in propranolol-treated patients. Five of 7 patients in the isradipine-treated group and 8 of 9 patients in the propranolol-treated group discontinued the therapy because of adverse reactions or treatment failure. Using Fisher's Exact Test, we found no significant difference in the relative frequency of individual adverse reactions between groups, although the absolute adverse reaction frequency was significantly higher with isradipine. This study demonstrates the effectiveness and safety of supplemental isradipine in the treatment of hypertension not controlled by hydrochlorothiazide alone.

Adult↗
PubMed1988

Diagnosis of hypertension in a family practice setting: a preliminary study of published protocol versus 24-hour ambulatory blood pressure monitoring.

Although there have been many recommendations in the medical literature regarding the proper evaluation of hypertensive patients, there have been few reports regarding physician compliance with such diagnostic protocols. To assess physician compliance with the diagnostic protocol published by the Joint National Committee for the Detection, Evaluation, and Treatment of High Blood Pressure (JNC), we reviewed the records of 181 hypertensive patients in the family practice clinic of a medical university. We found numerous discrepancies between the published protocol and actual practice. Antihypertensive medication was then discontinued in a small subset of the study group, and the diagnosis of hypertension was reevaluated by both JNC criteria and by 24-hour ambulatory blood pressure monitoring. As compared with 24-hour ambulatory measurements, the JNC criteria were ineffective in properly classifying hypertensive status of the patients in this small subset.

Adult↗
PubMed1987

How can we diagnose coronary heart disease in hypertensive patients?

Chest pain is a common complaint among hypertensive patients. Hypertension and coronary heart disease each may present with symptoms and signs that are clinically indistinguishable. Noninvasive testing by routine exercise stress testing and stress radionuclide angiography are not reliably predictive of ischemia resulting from obstructive epicardial coronary artery disease and should be abandoned for that diagnostic purpose. Noninvasive thallium-201 myocardial perfusion imaging for this purpose may prove to be a valuable tool, avoiding the risk and expense of coronary arteriography. However, carefully performed prospective studies are not available. Because of the high prevalence of both diseases, a high priority must be given to obtaining these data and evaluating other noninvasive methods (especially positron emission tomography) if they appear promising.

Cardiomegaly↗