Previous in vitro and in vivo studies have shown that norepinephrine, acting through alpha(1A)-adrenoceptors, stimulates hypertrophy, proliferation, and migration of vascular smooth muscle cells and adventitial fibroblasts and may contribute to neointimal growth, lumen loss, and inward remodeling caused by iatrogenic wall injury and vascular disease. Our present aim was to determine whether intravenous administration of the alpha(1A)-adrenoceptor antagonist KMD-3213, at dosages without systemic hemodynamic effects, inhibits wall growth after injury. Inhibition of alpha(1A)-adrenoceptors with 12.8 and 32 microg/kg KMD-3213 had no effect on arterial pressure or renal and hindquarter resistances in anesthetized rats. A second group then received carotid balloon injury and continuous intravenous KMD-3213 at 4 and 10 microg x kg(-1) x h(-1) for 2 wk. Mean, systolic, and diastolic arterial pressures and heart rate of conscious unrestrained rats were unaffected. KMD-3213 reduced neointima growth by approximately 30 and 46% at the two doses (P < 0.01). These data support the novel hypothesis that a direct alpha(1A)-adrenoceptor-dependent trophic action of catecholamines is augmented by injury and may contribute significantly to hypertrophic vascular disease.
Introduction
The purposes of this study are to investigate the cost-effectiveness of an implantable carotid body stimulator (Rheos®) for treating resistant hypertension and determine the range of starting systolic blood pressure (SBP) values where the device remains cost-effective.
Methods
A Markov model compared a 20 mmHg drop in SBP from an initial level of 180 with Rheos® to failed medical management in a hypothetical 50-year old cohort. Direct costs (2007$), utilities and event rates for future myocardial infarction, stroke, heart failure and end-stage renal disease were modeled. Sensitivity analyses tested the assumptions in the model.
Results
The incremental cost-effectiveness ratio (ICER) for Rheos® was $64,400 per quality-adjusted life-year (QALY) using Framingham-derived event probabilities. The ICER was <$100,000/QALY for SBPs ≥142. A probability of device removal of <1% per year or SBP reductions of ≥24 mmHg were variables that decreased the ICER below $50,000/QALY. For cohort characteristics similar to ASCOT-BPLA trial participants, the ICER became $26,700/QALY. Two-way sensitivity analyses demonstrated that lowering SBP 12 mmHg from 220 or 21 mmHg from 140 were required.
Conclusions
Rheos® may be cost-effective, with an ICER between $50,000-$100,000/QALY. Cohort characteristics and efficacy are key to the cost-effectiveness of new therapies for resistant hypertension.
Primary hypertension among children and adolescents is increasing in prevalence and has been associated with the sequela of left ventricular hypertrophy (LVH), defined by increased left ventricular mass index (LVMI). The association between high blood pressure (BP) and LVMI in an otherwise healthy pediatric population is not well understood. We evaluated the relationship between measures of BP and LVMI in a group of healthy adolescents. We conducted a retrospective review of 55 high school athletes who participated in a community health screen, which included collecting BP readings and limited echocardiograms. End points included prevalence of BP in the ranges of hypertension and prehypertension, prevalence of LVH, and relationship between BP indices and LVMI. No individuals were found to be in the hypertensive range, and there were 13 (24%) in the prehypertensive range. Only one (2%) adolescent met LVH criteria. In multivariable regression analysis, increasing systolic BP index was the only variable significantly associated with greater LVMI (P=0.028). In a healthy cohort of lean adolescents, BP in the prehypertensive range was common in the community health screen setting. Increasing systolic BP index was significantly associated with LVMI.
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