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Biomedical subjects

L R Krakoff

Publications and source records attributed to L R Krakoff.

At least 19 recordsLinked to original sources
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↗
PubMed1999

Sex difference in response of blood pressure to calcium antagonism in the treatment of moderate-to-severe hypertension.

BACKGROUND: The pressor response to examination in the clinic setting is called the 'white coat effect' (WCE). This response may be a confounder when investigators use clinic blood pressure as a measure of response to antihypertensive therapy. OBJECTIVE: ;To study the effect of the pressor response by evaluating the sex-specific effect of treatment with calcium antagonism on blood pressure measured in the clinic and by ambulatory blood pressure monitoring (ABPM). METHODS: Untreated hypertensive subjects (n=39) with seated clinic diastolic blood pressures (DBP) > or = 100 and < or = 130mmHg were studied. Same-day clinic systolic blood pressure (SBP) and ambulatory SBP were obtained after 1 week of placebo, and after 1 month of treatment with either nifedipine or verapamil in a randomized, blinded, parallel trial. RESULTS: With placebo, women s average SBP was 18+/-;4mmHg lower than clinic SBP. By contrast, men s average SBP with placebo was 4+/-15mmHg lower than clinic SBP. There was a significantly greater reduction in clinic SBP for women than there was for men after 1 month of treatment (by 33+/-13 versus 18+/-18mmHg, P<0.005). However, reduction in ambulatory SBP after 1 month was the same for both sexes (20+/-11 versus 19+/-12mmHg). CONCLUSIONS: In this study of moderate-to-severe hypertensives, the large WCE measured for women, which markedly diminished with treatment, accounts for the observed sex difference in response of clinic SBP to calcium antagonism. By contrast, with ABPM there was an equivalent response to treatment for both sexes. Use of ABPM could be a valuable means of eliminating the WCE as a confounder in clinical research.

Blood Pressure↗
PubMed1998

Relation among left ventricular mass, insulin resistance, and blood pressure in nonobese subjects.

Because left ventricular (LV) mass (LVM) is a powerful predictor of future cardiovascular events, it is important to identify hemodynamic and nonhemodynamic factors that increase LVM. We studied the separate contribution to LVM of daily arterial blood pressure (BP) and insulin resistance in a consecutive series of 29 (mean+/-SD age, 43+/-13 yr) nonobese (body mass index, 24+/-1.8 kg/m2), nondiabetic, glucose-tolerant subjects with untreated borderline or mild hypertension. The insulin sensitivity index (SI) was quantitatively determined from the frequently sampled iv glucose tolerance test. BP was characterized by ambulatory 24-h BP monitoring, and LVM index (LVMI) was determined by two-dimensional directed M-mode echocardiography. LVMI was directly related to 24-h mean BP (r=0.47; P=0.01). LMVI was also significantly related to Si (r=-0.43; P=0.02). In this nonobese group, neither LVMI nor Si was related to body mass index or age. After adjustment for the influence of BP on LVMI, a significant relation remained between LVMI and Si (P < 0.05). We conclude that in nonobese subjects with high normal BP, insulin sensitivity is related to LVM independently of BP and may be an important modulator of LV growth. In addition to a reduction of arterial BP, optimal prevention of LV hypertrophy in hypertensives may require improved insulin sensitivity.

Adolescent↗
PubMed1997

Confirmation or exclusion of stage I hypertension by ambulatory blood pressure monitoring.

Criteria for the diagnosis or exclusion of hypertension using ambulatory blood pressure monitoring have not been agreed upon. We designed this study to provide a statistically based guide for using results of ambulatory blood pressure monitoring to resolve this issue. To generate this information, we used a database of 228 subjects (135 men, 93 women; average age, 45 years) referred by their primary physicians over the past 7 years for evaluation of borderline or stage I hypertension (average blood pressure, 148/92 mm Hg; SD, +/-17.5/12.2 mm Hg). In this population, the pooled SDs of systolic and diastolic ambulatory blood pressures were 13.8 and 11.6 mm Hg, respectively. Using the pooled SD, we calculated the probability that a patient's blood pressure falls within the hypertensive range (> 140/90 mm Hg). The 95% confidence interval for each subject's blood pressure was also determined. For example, if 40 ambulatory blood pressure measurements are performed on a subject and the average systolic ambulatory blood pressure is 137 mm Hg, then there is a 10% probability that the patient's "true" average blood pressure is actually in the hypertensive range. By contrast, if the systolic pressure is 143 mm Hg, there is a 90% probability that the patient is hypertensive. This approach may be useful for clinical decision making and also for the design of clinical trials.

Adolescent↗