Left Ventricular Diastolic Function in Nigerian Patients with Essential Hypertension: A Retrospective Study to Compare Angiotensin Converting Enzyme Inhibitors, Calcium Channel Blockade or Their Combination.

BACKGROUND: Hypertension in blacks imposes a greater left ventricular hypertrophy, and accelerated heart failure onset. We evaluated and compared the echocardiographically determined systolic and left ventricular diastolic functional indices in Nigerian hypertensive patients, associated with the chronic use of ACE inhibitors, Calcium channel blockers (CCB) or their combinations. METHODS: Ejection fraction -EF, intraventricular relaxation time (IVRT), E/A peak velocity ratio, E wave deceleration time] as well as the left ventricular mass index (LVMI) was undertaken among 41 Nigerian patients with essential hypertension only, on treatment for 4-6 months prior. The 41 patients (aged 59 +/- 10 years, 40% females) were divided into three groups; those receiving (i) ACE inhibitors; or (ii) CCB or (iii) combination of ACEI and CCB. All the three groups had a background of diuretic treatment for optimal blood pressure control. RESULTS: There were no statistically significant differences in the mean LVMI or sitting blood pressure between treatment groups. E/A ratio for ACEI treatment was 1.06 +/- 0.44, CCB 0.74 +/- 0.19, and for ACEI + CCB 0.87 +/- 0.26 (F = 3.29, P = 0.048 anova). The 95% confidence interval for the E/A ratio on ACEI was 0.8 to 1.33. The A wave duration time integral (AVVTi) were all abnormally large, but showed a significant between treatment group difference (P = 0.037, anova). The values were 21.9 +/- 4.7 for ACEI, 25.3 +/- 6.3 for CCB, and least at 20.1 +/- 3.6 cm for the ACE + CCB combination. Similarly, the IVRT was lowest and <100 ms with ACEI + CCB being 93 +/- 18 ms, ACEI 115 +/- 23 ms, and CCB being 117 +/- 22 ms (F = 4.92, P = 0.01, anova). The 95% CI for IVRT on ACEI + CCB was 82 to 104 ms. There were no between treatment group differences in systolic contractility, (fractional shortening or EF). CONCLUSIONS: The results indicate that use of an antihypertensive drug regime inclusive of an ACE inhibitor (+/-CCB) may be associated with greater salutary effect on indices of diastolic function, (E/A > 1, lower AVVTi, IVRT < 100 ms) even in the presence of an equivalent effect on systolic function and blood pressure.

Effect of cirrhosis and liver transplantation on the gender difference in QT interval.

The effect of gender on the QT interval in patients with cirrhosis before and after liver transplantation and the relation between the QT interval and changes in gender hormones after liver transplantation were assessed. The study showed that (1) physiologic gender difference in the QTc interval is abolished in cirrhosis, and it is not restored after liver transplantation, and (2) gender hormone concentrations had no effect on the QTc interval.

The interaction between St John's wort and an oral contraceptive.

OBJECTIVES: The popular herbal remedy St John's wort is an inducer of cytochrome P450 (CYP) 3A enzymes and may reduce the efficacy of oral contraceptives. Therefore we evaluated the effect of St John's wort on the disposition and efficacy of Ortho-Novum 1/35 (Ortho-McNeil Pharmaceutical, Inc, Raritan, NJ), a popular combination oral contraceptive pill containing ethinyl estradiol (INN, ethinylestradiol) and norethindrone (INN, norethisterone). METHODS: Twelve healthy premenopausal women who were using oral contraception (>3 months) received a combination oral contraceptive pill (Ortho-Novum 1/35) for 3 consecutive 28-day menstrual cycles. During the second and third cycles, the participants received 300 mg St John's wort 3 times a day. The serum concentrations of ethinyl estradiol (day 7), norethindrone (day 7), follicle-stimulating hormone (days 12-16), luteinizing hormone (days 12-16), progesterone (day 21), and intravenous and oral midazolam (days 22 and 23) were determined in serial blood samples. The incidence of breakthrough bleeding was quantified during the first and third cycles. RESULTS: Concomitant use of St John's wort was associated with a significant (P <.05) increase in the oral clearance of norethindrone (8.2 +/- 2.7 L/h to 9.5 +/- 3.4 L/h, P =.042) and a significant reduction in the half-life of ethinyl estradiol (23.4 +/- 19.5 hours to 12.2 +/- 7.1 hours, P =.023). The oral clearance of midazolam was significantly increased (109.2 +/- 47.9 L/h to 166.7 +/- 81.3 L/h, P =.007) during St John's wort administration, but the systemic clearance of midazolam was unchanged (37.7 +/- 11.3 L/h to 39.0 +/- 10.3 L/h, P =.567). Serum concentrations of follicle-stimulating hormone, luteinizing hormone, and progesterone were not significantly affected by St John's wort dosing (P >.05). Breakthrough bleeding occurred in 2 of 12 women in the control phase compared with 7 of 12 women in the St John's wort phase. The oral clearance of midazolam after St John's wort dosing was greater in women who had breakthrough bleeding (215.9 +/- 66.5 L/h) than in those who did not (97.5 +/- 37.2 L/h) (P =.005). CONCLUSION: St John's wort causes an induction of ethinyl estradiol-norethindrone metabolism consistent with increased CYP3A activity. Women taking oral contraceptive pills should be counseled to expect breakthrough bleeding and should consider adding a barrier method of contraception when consuming St Johns wort.

Adjunctive sympathoplegic therapy to ACE inhibition in Blacks with congestive heart failure: a comparison of alpha-1 with beta-1 blockade on exercise tolerance and cardiac sympathovagal reflex activity.

OBJECTIVES: Congestive heart failure (CHF) is characterized by an initial compensatory, but subsequently deleterious, activation of both the renin-angiotensin (RAS) and the sympathetic nervous system (SNS). Incomplete suppression of the SNS may contribute to the residual mortality during optimal ACE inhibitor therapy in CHF. Carvedilol, a mixed alpha and beta-blocker with antioxidant properties, and other pure beta-adrenoceptor blockers reduce morbidity and mortality in Caucasians with CHF. However, beta-blocker monotherapy is of poor efficacy in Blacks with essential hypertension or in the treatment of glaucoma. The efficacy of beta-blockers in the treatment of African Americans with congestive heart failure is a controversial issue with conflicting findings. The aims of the present study were to examine and compare the cardiovascular, autonomic, and clinical effects of additional alpha-1, or beta-1 blockade in ACE-inhibitor treated Black patients with moderate to severe CHF. METHODS: Twenty-eight Nigerian patients with chronic CHF stabilized on digoxin and diuretics, were randomized to 3 groups of similar demographics according to a single blind, parallel group design. The patients were aged 53 +/- 6 years, and comprised 14 men and 14 women, with a mean cardiothoracic ratio of 0.66 +/- 0.03, and ejection fraction of 0.38 +/- 0.10, 60% hypertensive etiology. Group 1 patients received 5 mg enalapril alone, group 2 received 5 mg enalapril + 1 mg prazosin, and group 3 received 5 mg enalapril + 50 mg atenolol. All medication was taken daily for 4 weeks. Blood pressure, heart rate, pressure rate product, 6-minute walk test, NYHA class, and cardiac autonomic reflexes were measured at baseline and again at 2 and 4 weeks of treatment. Two-way repeated measures ANOVA, and a one-way ANOVA were used in data analysis. RESULTS: The 3 treatments caused significant (P<.001 ANOVA) and similar improvements for the NYHA class (-1.0 to -1.6), and increased the 6-minute distance covered (+130 m to +205 m). Although no treatment differences were observed, a trend suggesting a greater improvement with enalapril + atenolol became apparent. By the fourth week, the sympathoplegic treatments, enalapril + atenolol, and enalapril + prazosin, caused significant reductions in the pressure rate product (-3726 +/- 1885 mm Hg x beats/min; -3498 +/- 396 mm Hg beats/min, respectively), (compared to enalapril alone (-1349 +/- 894 mm Hg x beats/min) (P<.001 ANOVA). During the Valsalva maneuver, the phase IV bradycardia were significantly greater after treatment with enalapril + atenolol (944 +/- 66 msec) or with enalapril + prazosin (825 +/- 48 msec), compared to enalapril alone (760 +/- 45 msec) (P<.001 ANOVA). The phase II Valsalva tachycardia were similar between treatments. The respiratory sinus arrhythmia ratio increased significantly (P<.005 ANOVA) and equally on all treatments. However, the pressor and chronotropic responses to forearm isometric handgrip increased significantly on the enalapril + prazosin combination (P<.02), compared to the other treatments. CONCLUSIONS: Our findings demonstrated not only the safety of providing additional therapy with alpha-1 or beta-1 receptor blockade concurrent with ACE inhibition in Blacks with CHF, but also the resultant improvement in exercise tolerance and NYHA class. Compared to using ACE inhibition alone, the combined therapies caused a marked reduction in the pressure rate product, an index of myocardial oxygen consumption, and a greater enhancement of cardiac parasympathetic activity. Selective beta-1 blockade caused a greater enhancement of central baroreceptor vagal activity compared to alpha-1 blockade. Conversely, the pressor and chronotropic abnormalities during forearm isometric handgrip in CHF, were normalized by alpha-1, but not beta-1, blockade. Thus, the combined reflex cardiac vagal augmentation following selective beta-1 blockade, and the hemodynamic effects of alpha-1 antagonism with concurrent ACE inhibition, may be of major therapeutic and prognostic benefit in Blacks with non-ischemic (hypertensive) CHF stabilized on digoxin and diuretics.

Clinical effects of grapefruit juice-nifedipine interaction in a 54-year-old Nigerian: a case report.

Grapefruit juice is known to increase the oral bioavailability of dihydropyridine calcium channel blockers, including nifedipine, by reducing presystemic clearance. The nature and magnitude of this interaction has not been studied in black Africans. Previous studies have reported reduced systemic clearance of nifedipine in this population, suggesting altered risk from the interaction of grapefruit juice and nifedipine. We report a case of a nifedipine-grapefruit juice adverse interaction in a Nigerian to draw attention to the problem and further sensitize practitioners.