Is it the blood pressure or the blood vessel?

Cardiovascular Disease Progression: A Target for Therapy?

Clinical research aimed at preventing cardiovascular disease has focused on the effect of interventions to reduce risk factors on the incidence of future morbid events. Disease progression, which likely serves as a necessary prerequisite for morbid events, has not served as a target for therapy. The Rasmussen Center at the University of Minnesota has, for the past 18 years, been performing a noninvasive cardiovascular evaluation in individuals with no history of cardiovascular disease. The studies, performed in 1 hour in one room, provide a comprehensive noninvasive assessment of the severity of functional and structural abnormalities in the small arteries, the large arteries and the left ventricle, the target organs for most cardiovascular morbid events. Preliminary follow-up data have revealed a striking relationship between the Disease Score, which represents the sum of the abnormal tests, and the risk of future morbid events. In order to develop strategies to prolong cardiovascular disease-free life expectancy, studies in early stages of disease aimed at slowing disease progression should be encouraged.

Enhanced vasorelaxation effect of endogenous anandamide on thoracic aorta in renal vascular hypertension rats

Emerging evidence has indicated that anandamide (AEA) is able to stimulate vasorelaxation in both spontaneously hypertensive rats (SHRs) and L-NAME-induced hypertensive rats. Yet it remains unknown whether AEA modulates vasomotion of the aorta in renovascular hypertensive (RVH) rats. The aim of present study is to explore the effect of AEA on the relaxation of thoracic aortas in two-kidney one-clip (2K1C)-induced RVH rats. It is demonstrated that AEA stimulates a pronounced relaxation in the aortas of 2K1C rats compared with sham rats. The enhanced relaxation caused by AEA in aortas from 2K1C rats was diminished in the presence of the cannabinoid receptor-1 (CB₁ ) antagonist AM251 and the CB₂ receptor antagonist AM630. Likewise, the vasodilation action of AEA was blocked in L-NAME-treated or endothelium-denuded aortas. The Western blot results revealed that the expression of CB₁ and CB₂ receptors was increased in the 2K1C rat aortas compared with sham rats. The phosphorylation of endothelial nitric oxide synthase (p-eNOS) at the activation site Ser1177 was enhanced in AEA-treated rings from 2K1C rats in both time-dependent and dose-dependent manners. The augmented p-eNOS expression was inhibited by the co-treatment with AM251 or AM630. Taken together, the present study demonstrated that AEA enhanced endothelium-dependent aortic relaxation through activation of both CB₁ and CB₂ receptors and P-eNOS/NO pathway in 2K1C rats.

Comparative effectiveness of a fixed-dose combination of losartan + HCTZ versus bisoprolol + HCTZ in patients with moderate-to-severe hypertension: results of the 6-month ELIZA trial

Background

The aim of this study was to compare the antihypertensive efficacy of losartan 100 mg + hydrochlorothiazide (HCTZ) 25 mg versus bisoprolol 10 mg + HCTZ 25 mg and their influence on arterial stiffness and central blood pressure (BP).

Methods

Of 60 patients with a mean BP of 173.3 ± 1.7/98.4 ± 1.2 mmHg, 59 were random-ized to losartan + HCTZ (n = 32) or bisoprolol + HCTZ (n = 27). Amlodipine was added if target BP was not achieved at 1 month, and doxazosin was added if target BP was not achieved after 3 months. Body mass index, office and 24-hour ambulatory BP, pulse wave velocity (carotid-femoral [PWVE] and radial [PWVM]), noninvasive central systolic BP, augmentation index (AIx), laboratory investigations, and electrocardiography were done at baseline and after 6 months of treatment.

Results

Losartan + HCTZ was as effective as bisoprolol + HCTZ, with target office BP achieved in 96.9% and 92.6% of patients and target 24-hour BP in 75% and 66.7% of patients, respectively, after 6 months. Effective treatment of BP led to significant lowering of central systolic BP, but this was decreased to a significantly (P < 0.05) greater extent by losartan + HCTZ (−23.0 ± 2.3 mmHg) than by bisoprolol + HCTZ (−15.4 ± 2.9 mmHg) despite equal lowering of brachial BP. Factors correlated with central systolic BP and its lowering differed between the treatment groups. Losartan + HCTZ did not alter arterial stiffness patterns significantly, but bisoprolol + HCTZ significantly increased AIx. We noted differences in ΔPWVE, ΔPWVM, and ΔAIx between the groups in favor of losartan + HCTZ. Decreased heart rate was associated with higher central systolic BP and AIx in the bisoprolol + HCTZ group, but was not associated with increased AIx in the losartan + HCTZ group.

Conclusion

Although both treatments decreased both office and 24-hour BP, losartan + HCTZ significantly decreased central systolic BP and had a more positive influence on pulse wave velocity, with a less negative effect of decreased heart rate on AIx and central systolic BP.

Blood pressure tracking over the adult life course: patterns and correlates in the Framingham heart study

The extent to which select vascular risk factors differentially influence blood pressure (BP) is incompletely understood. Thus, we used multilevel modeling to analyze serial BP measurements using 21 732 person-observations obtained on Framingham Heart Study participants (mean age, 38 years, 52% women; 4993 unique individuals) over a 28-year period. We related longitudinal tracking of each BP measure (systolic BP, diastolic BP, mean arterial pressure, and pulse pressure) to age, sex, body mass index, smoking, diabetes mellitus, total/high-density lipoprotein cholesterol ratio, and heart rate. In multivariable-adjusted analyses, we observed that older age, male sex, greater body mass index, and higher heart rate were positively associated with increase in all BP measures (P<0.0001). Notably, higher total/high-density lipoprotein cholesterol ratio was associated with greater mean arterial pressure (P<0.01). Conversely, diabetes mellitus and smoking were associated with higher pulse pressure (P<0.01). We also observed effect modification by sex: the increase in pulse pressure with age and body mass index was more pronounced in women compared with men (P<0.0001). All BP measures tracked at higher levels in both men and women with multiple vascular risk factors. Taken together, our longitudinal observations in a large community-based sample demonstrate a greater pulsatile load in women than in men with increasing age. We also observed a differential impact of select vascular risk factors on the individual components of BP, underscoring distinct regulation of these measures over the life course.

Association of capillary density and function measures with blood pressure, fasting plasma glucose, and insulin sensitivity

The pathophysiology underlying the association between hypertension and insulin resistance remains unclear. The study purpose was to determine whether reduced capillary density and/or function underlie, and may therefore explain, this association. The study was conducted on 115 black and non-black participants aged 18 to 55 years: 91 with normal blood pressure (systolic blood pressure [SBP] <130 mm Hg) and 24 with mild blood pressure elevation (SBP 130-159 mm Hg). Capillary density and function were quantified using direct capillaroscopy measures. Insulin sensitivity (IS) was estimated using the Quantitative Insulin Sensitivity Check Index (QUICKI). Endothelial function (EF) was measured using strain-gauge plethysmography. Data were analyzed by linear regression adjusted for age, sex, race, and body mass index (BMI). After adjustment for BMI, capillary density and function measures were significant predictors of SBP ( P<.01), fasting plasma glucose (P=.012, P=.03, and P=.004, respectively), and EF (P=.033, P=.001, and P=.009, respectively). However, none of the capillary measures were significant predictors of fasting insulin or IS. These capillaroscopy data demonstrated an association with SBP but not insulin resistance, suggesting that capillary measures are unlikely to explain the association between hypertension and insulin resistance, at least with modest degrees of blood pressure elevation.

Alterations in capillary morphology are found in mild blood pressure elevation

OBJECTIVES

Remodeling of small resistance arteries is an early sign of target organ damage in hypertension. Peripheral capillary morphology abnormalities in hypertension are not well studied. The study objective was to determine whether altered capillary morphology is associated with SBP, DBP, or both in individuals without and with mild blood pressure elevation (SBP = 130-160 mmHg). Another objective was to determine whether capillary morphology is associated with minimum forearm vascular resistance, a measure of altered resistance artery structure.

METHODS

Participants included 115 nonpregnant, nondiabetic individuals 23-55 years of age. A five-component morphology score (distribution, tone, configuration, hypertrophy, and extravasates) was developed to describe fingernail bed capillaries visualized using venous congestion in digital photomicrographs. Multiple linear regression models adjusted for age, sex, race, tobacco use, hyperglycemia, dyslipidemia, and renal function were used to analyze the relationship between SBP, DBP, and minimum forearm vascular resistance with the morphology score.

RESULTS

The total morphology score was significantly associated with SBP and DBP as well as minimum forearm vascular resistance (P < 0.005 for all). Among the five individual morphology score components, hypertrophy was significantly associated with SBP and DBP (P = 0.002 and 0.001, respectively), whereas extravasates were significantly associated with SBP only (P = 0.002).

CONCLUSION

A five-component capillary morphology score is associated with SBP, DBP, and altered resistance artery structure in individuals with and without mild blood pressure elevation. These observations suggest that target organ damage at the level of the microcirculation can be detected using capillary morphology.

Functional capillary rarefaction in mild blood pressure elevation

Capillary rarefaction is described in patients with moderate to severe hypertension. The study objective was to determine if structural and/or functional capillary rarefaction is detectable and associated with endothelial dysfunction in patients with mild blood pressure elevation (HBP: Systolic blood pressure 130 - 160 mm Hg). Capillary density was quantified by direct capillaroscopy in 110 nondiabetic black and non-black subjects. Endothelial function was quantified by plethysmographic measures of flow-mediated vasodilation. Compared to normotensives (NBP: N = 90), functional capillary rarefaction was detected in HBP (N = 20; P<0.001). Functional capillary density measures correlated with endothelial function (P<0.001). Functional, but not structural, capillary rarefaction is detectable and associated with endothelial dysfunction in both black and non-black individuals with mild blood pressure elevation.

Capillary rarefaction in treated and untreated hypertensive subjects

This study aimed to determine if capillary rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural capillary rarefaction measures were not different between the three groups. Functional capillary rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation.

Coadministered amlodipine and atorvastatin produces early improvements in arterial wall compliance in hypertensive patients with dyslipidemia

BACKGROUND

Combining statins with antihypertensive therapy has been demonstrated to provide an early reduction in cardiovascular events. This nested substudy of the AVALON trial assessed the effects of coadministered amlodipine and atorvastatin vs. either therapy alone or placebo on arterial compliance, to evaluate the vascular benefits of coadministered therapy.

METHODS

During an initial 8-week, double-blind phase, patients with concomitant hypertension and dyslipidemia were randomized into four treatment groups (placebo, amlodipine 5 mg, atorvastatin 10 mg, or coadministered amlodipine 5 mg and atorvastatin 10 mg). The sustained effect of combined therapy was evaluated during subsequent 8-week, single-blind, and 12-week, open-label periods. In the single-blind phase, all patients were coadministered amlodipine 5 mg and atorvastatin 10 mg, which were then titrated to optimize blood pressure and low-density lipoprotein cholesterol control during the open-label phase. Arterial compliance was assessed every 4 weeks using the HDI/Pulsewave CR-2000.

RESULTS

Overall, 668 patients (61% male, mean age 55 years) were randomized to treatment. A 19% improvement in small artery compliance (C2) was observed with coadministered amlodipine and atorvastatin from baseline to week 8, which was significantly greater than with either treatment alone or with placebo (P = 0.03 to 0.0001). After 28 weeks, C2 was increased from baseline in all groups, but the overall improvement was greatest in the group receiving coadministered drugs for the entire study period (P < 0.05).

CONCLUSIONS

Early and sustained improvement in small artery compliance was observed following coadministration of amlodipine and atorvastatin, thus demonstrating a vascular benefit with simultaneous treatment of hypertension and dyslipidemia.

Reducing cardiovascular risk by blockade of the renin-angiotensin-aldosterone system

Many factors contribute to the overall risk of cardiovascular disease (CVD) in a given patient. Activation of the renin-angiotensin-aldosterone system (RAAS) is pivotal in the pathophysiology of CVD and renal disease and appears to place individuals at high risk for cardiovascular (CV) and renal events. Results from many large-scale, long-term clinical trials have demonstrated that RAAS blockade with an angiotensin-converting-enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB) can significantly decrease CV and renal morbidity and mortality in a wide range of patients. Some of the clinical benefits derived from use of these agents appears to be independent of their ability to lower blood pressure. The combined use of an ACEI and an ARB for antihypertensive therapy has begun to receive considerable attention. Such an approach may seem counterintuitive, but ACEIs and ARBs have distinct and potentially complementary pharmacologic effects. Results from clinical trials thus far suggest that combination therapy with an ACEI plus an ARB may be a rational choice in patients with chronic activation of the RAAS, including those with heart failure or impaired left ventricular systolic function, diabetes, proteinuria, impaired renal function, recent myocardial infarction, or multiple CV risk factors. Results from ongoing, large-scale, clinical endpoint trials will provide important additional information about the benefits of dual RAAS inhibition in patients at high risk for CV morbidity and mortality.