Arterial Compliance In Hypertension

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138400/1/imj49.pd

SUPPRESSION OF SYMPATHETIC NERVOUS FUNCTION IN LOW-RENIN ESSENTIAL HYPERTENSION

Study of general haemodynamics in 15 patients with low-renin essential hypertension showed haemodynamic and pathophysiological heterogeneity. However, there was suppression of sympathetic nervous system function in all low-renin patients, regardless of haemodynamic pattern. Subnormal sympathetic nervous activity was manifested by a low normal mean plasma-noradrenaline concentration at rest, diminished noradrenaline responsiveness to postural stimulation, and a reduced blood-pressure response to the indirectly acting sympathomimetic amine tyramine. It is proposed that the syndrome of low-renin essential hypertension is of diverse aetiology, but with secondary sympathetic nervous system underactivity as a feature common to the various forms. The low plasmarenin activity is probably an expression of defective sympathetic nervous system stimulation of renin release.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21720/1/0000112.pd

Cardiovascular risk reduction in hypertensive black patients with left ventricular hypertrophy The life study

AbstractObjectivesWe report on a subanalysis of the effects of losartan and atenolol on cardiovascular events in black patients in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study.BackgroundThe LIFE study compared losartan-based to atenolol-based therapy in 9,193 hypertensive patients with left ventricular hypertrophy (LVH). Overall, the risk of the primary composite end point (cardiovascular death, stroke, myocardial infarction) was reduced by 13% (p = 0.021) with losartan, with similar blood pressure (BP) reduction in both treatment groups. There was a suggestion of interaction between ethnic background and treatment (p = 0.057).MethodsExploratory analyses were performed that placed LIFE study patients into black (n = 533) and non-black (n = 8,660) categories, overall, and in the U.S. (African American [n = 523]; non-black [n = 1,184]).ResultsA significant interaction existed between the dichotomized groups (black/non-black) and treatment (p = 0.005); a test for qualitative interaction was also significant (p = 0.016). The hazard ratio (losartan relative to atenolol) for the primary end point favored atenolol in black patients (1.666 [95% confidence interval (CI) 1.043 to 2.661]; p = 0.033) and favored losartan in non-blacks (0.829 [95% CI 0.733 to 0.938]; p = 0.003). In black patients, BP reduction was similar in both groups, and regression of electrocardiographic-LVH was greater with losartan.ConclusionsResults of the subanalysis are sufficient to generate the hypothesis that black patients with hypertension and LVH might not respond as favorably to losartan-based treatment as non-black patients with respect to cardiovascular outcomes, and do not support a recommendation for losartan as a first-line treatment for this purpose. The subanalysis is limited by the relatively small number of events

Reliability of echocardiography in assessing cardiac output

Because of the potential benefits from a noninvasive technique in assessing cardiac output, we compared cardiac output estimates from left ventricular echocardiograms with results obtained simultaneously by a standard technique, dye dilution in 10 healthy normal volunteers. During rest, cardiac outputs by echocardiographic and dye dilution techniques were reproducible and not significantly different. Increases in cardiac output produced by intravenous infusion of isoproterenol (15 ng/kg/min for 4 min) were accurately estimated by echocardiography in subjects whose stroke volume increased less than 40%, but were significantly underestimated when stroke volume increased more than 40%. Decreased cardiac output produced by intravenous propranolol (0.2 mg/kg) was comparable by both methods. Although echocardiography accurately estimated mean cardiac output for the group it over- or underestimated cardiac output in individual subjects. We propose that echocardiography can reliably estimate cardiac output in groups at rest and when stroke volume changes less than 40%. Einer nicht invasiven Methode zur akkuraten Bestimmung des Herzminutenvolumens (HMV) käme eine große Bedeutung zu. Wir verglichen deshalb aus links-ventriculären Echocardiogrammen bestimmte mit gleichzeitig mittels Farbstoffverdünnungsmethode (Cardiogreen) bestimmten HMV in 10 normalen Versuchspersonen. Unter Ruhebedingungen war das HMV mit beiden Methoden reproduzierbar und nicht signifikant verschieden. Anstiege des HMV nach intravenöser Infusion von Isoproterenol (15 ng/kg/min über 4 min) wurden mittels Echocardiographie zuverlässig nur bei Probanden erfaßt, bei denen das Schlagvolumen weniger als 40% anstieg. Bei größeren Anstiegen wurde der Anstieg des HMV signifikant unterschätzt. Ein erniedrigtes HMV nach intravenöser Injektion von Propranolol (0,2 mg/kg) wurde von beiden Methoden gleichermaßen erfaßt. Obwohl das HMV mittels Echocardiographie für das Untersuchungskollektiv nicht signifikant von den Farbstoffverdünnungswerten verschieden war, wichen die echocardiographisch bestimmten HMV bei einzelnen Probanden deutlich von den Farbstoffverdünnungswerten ab. Unsere Ergebnisse zeigen, daß die links-ventriculäre Echocardiographie zur Bestimmung des HMV in Gruppen und bei Änderungen des Schlagvolumens von weniger als 40% benutzt werden kann.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45985/1/109_2005_Article_BF01746199.pd

Relation of renin status to neurogenic vascular resistance in borderline hypertension

The relation of renin-angiotensin status to general hemodynamics and to neurogenic vascular resistance was studied in patients with borderline hypertension. Plasma renin activity during standing was referred to a standard renin-urinary sodium nomogram derived from 18 normal subjects. Among 22 patients with borderline hypertension the renin level was high in 8, low in 4 and within normal limits in the remaining 10. In patients with borderline hypertension and high or normal levels of plasma renin activity, the blood pressure elevation was due to increased total peripheral vascular resistance. In contrast, in patients with low renin borderline hypertension, total peripheral resistance was not significantly elevated; the blood pressure elevation reflected a cardiac index 12 percent higher than that in normal subjects.The neurogenic contribution to total peripheral vascular resistance was assessed by studying the effects of alpha adrenergic blockade with phentolamine, after prior autonomic blockade of the heart with atropine (0.04 mg/kg body weight) and propranolol (0.2 mg/kg). Phentolamine (15 mg) produced an immediate reduction in total peripheral resistance of 12.0 +/- 6.7 percent in patients with high renin borderline hypertension (P It is concluded from these preliminary data that in high renin borderline hypertension the blood pressure elevation is sustained by neurogenic mechanisms. The elevated renin level in these patients is probably an expression of increased sympathetic nervous activity. Although the elevated plasma renin level may possibly be contributing to the generation of higher sympathetic tone, our data do not support a direct role of circulating angiotensin in the maintenance of the elevated vascular resistance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21969/1/0000378.pd

Effects of Lifestyle Modification on Telomerase Gene Expression in Hypertensive Patients: A Pilot Trial of Stress Reduction and Health Education Programs in African Americans.

BACKGROUND:African Americans suffer from disproportionately high rates of hypertension and cardiovascular disease. Psychosocial stress, lifestyle and telomere dysfunction contribute to the pathogenesis of hypertension and cardiovascular disease. This study evaluated effects of stress reduction and lifestyle modification on blood pressure, telomerase gene expression and lifestyle factors in African Americans. METHODS:Forty-eight African American men and women with stage I hypertension who participated in a larger randomized controlled trial volunteered for this substudy. These subjects participated in either stress reduction with the Transcendental Meditation technique and a basic health education course (SR) or an extensive health education program (EHE) for 16 weeks. Primary outcomes were telomerase gene expression (hTERT and hTR) and clinic blood pressure. Secondary outcomes included lifestyle-related factors. Data were analyzed for within-group and between-group changes. RESULTS:Both groups showed increases in the two measures of telomerase gene expression, hTR mRNA levels (SR: p< 0.001; EHE: p< 0.001) and hTERT mRNA levels (SR: p = 0.055; EHE: p< 0.002). However, no statistically significant between-group changes were observed. Both groups showed reductions in systolic BP. Adjusted changes were SR = -5.7 mm Hg, p< 0.01; EHE = -9.0 mm Hg, p < 0.001 with no statistically significant difference between group difference. There was a significant reduction in diastolic BP in the EHE group (-5.3 mm Hg, p< 0.001) but not in SR (-1.2 mm Hg, p = 0.42); the between-group difference was significant (p = 0.04). The EHE group showed a greater number of changes in lifestyle behaviors. CONCLUSION:In this pilot trial, both stress reduction (Transcendental Meditation technique plus health education) and extensive health education groups demonstrated increased telomerase gene expression and reduced BP. The association between increased telomerase gene expression and reduced BP observed in this high-risk population suggest hypotheses that telomerase gene expression may either be a biomarker for reduced BP or a mechanism by which stress reduction and lifestyle modification reduces BP. TRIAL REGISTRATION:ClinicalTrials.gov NCT00681200

Differing effects of antihypertensive drugs on the incidence of diabetes mellitus among patients with hypertensive kidney disease

The African American Study of Kidney Disease and Hypertension was a multicenter trial of African Americans with hypertensive kidney disease randomized to an angiotensin-converting enzyme inhibitor (ramipril), a beta-blocker (metoprolol succinate), or a calcium channel blocker (amlodipine besylate). We compared the incidence of type 2 diabetes mellitus (DM) and the composite outcome of impaired fasting glucose or DM (IFG/DM) for the African American Study of Kidney Disease and Hypertension interventions. Cox regression models were used to evaluate (post hoc) the association of the randomized interventions and the relative risk (RR) of DM and IFG/DM and to assess the RR of DM and IFG/DM by several prerandomization characteristics. Among 1017 participants, 147 (14.5%) developed DM; 333 (42.9%) of 776 participants developed IFG/DM. Respective DM event rates were 2.8%, 4.4%, and 4.5% per patient-year in the ramipril-, amlodipine-, and metoprolol-treated groups. The RRs of DM with ramipril treatment were 0.53 (P = .001) compared with metoprolol treatment and 0.49 (P = .003) compared with amlodipine treatment. Respective IFG/DM event rates were 11.3%, 13.3%, and 15.8% per patient-year in the ramipril-, amlodipine-, and metoprolol-treated groups. The RRs of IFG/DM with ramipril treatment were 0.64 (P<.001) compared with metoprolol treatment and 0.76 (P = .09) compared with amlodipine treatment. The RRs of DM and IFG/DM with amlodipine treatment compared with metoprolol treatment were 1.07 (P = .76) and 0.84 (P = .26), respectively. Ramipril treatment was associated with a significantly lower risk of DM in African Americans with hypertensive kidney disease than amlodipine or metoprolol treatment

Relationship of left ventricular hypertrophy and diastolic function with cardiovascular and renal outcomes in African Americans with hypertensive chronic kidney disease

African Americans with hypertension are at high risk for adverse outcomes from cardiovascular and renal disease. Patients with stage 3 or greater chronic kidney disease have a high prevalence of left ventricular (LV) hypertrophy and diastolic dysfunction. Our goal was to study prospectively the relationships of LV mass and diastolic function with subsequent cardiovascular and renal outcomes in the African American Study of Kidney Disease and Hypertension cohort study. Of 691 patients enrolled in the cohort, 578 had interpretable echocardiograms and complete relevant clinical data. Exposures were LV hypertrophy and diastolic parameters. Outcomes were cardiovascular events requiring hospitalization or causing death; a renal composite outcome of doubling of serum creatinine or end-stage renal disease (censoring death); and heart failure. We found strong independent relationships between LV hypertrophy and subsequent cardiovascular (hazard ratio, 1.16; 95% confidence interval, 1.05-1.27) events, but not renal outcomes. After adjustment for LV mass and clinical variables, lower systolic tissue Doppler velocities and diastolic parameters reflecting a less compliant LV (shorter deceleration time and abnormal E/A ratio) were significantly (P \u3c 0.05) associated with future heart failure events. This is the first study to show a strong relationship among LV hypertrophy, diastolic parameters, and adverse cardiac outcomes in African Americans with hypertension and chronic kidney disease. These echocardiographic risk factors may help identify high-risk patients with chronic kidney disease for aggressive therapeutic intervention

Coronary Artery Bypass Grafting in a Predominately Black Group of Patients

The preoperative profiles of a predominately non-white group of patients undergoing coronary artery bypass grafting were reviewed. Data were obtained from a retrospective analysis of medical records of 163 patients operated on at Howard University Hospital between July 1983 and July 1986. The analysis was carried out primarily to determine whether patients requiring myocardial revascularization were somehow different from their non-black counterparts. Ninety-one percent of the patients were black, 5 percent white, 0.5 percent Hispanic, and 3.5 percent others (Iranian, Filipino, etc)