Effect of antihypertensive therapy on aortic distensibility in patients with essential hypertension: comparison with trichlormethiazide, nicardipine and alacepril

Spironolactone Reduces Aortic Stiffness in Patients With Resistant Hypertension Independent of Blood Pressure Change

Background

Aortic stiffness is an independent predictor of cardiovascular events in patients with arterial hypertension. Resistant hypertension is often linked to hyperaldosteronism and associated with adverse outcomes. Spironolactone, a mineralocorticoid receptor antagonist, has been shown to reduce both the arterial blood pressure (BP) and aortic stiffness in resistant hypertension. However, the mechanism of aortic stiffness reduction by spironolactone is not well understood. We hypothesized that spironolactone reduces aortic stiffness in resistant hypertension independently of BP change.

Methods and Results

Patients with uncontrolled BP (≥140/90 mm Hg) despite use of ≥3 antihypertensive medications (including diuretics) were prospectively recruited. Participants were started on spironolactone at 25 mg/d, and increased to 50 mg/d at 4 weeks while other antihypertensive medications were withdrawn to maintain constant mean BP. Phase‐contrast cardiac magnetic resonance imaging of the ascending aorta was performed in 30 participants at baseline and after 6 months of spironolactone treatment to measure aortic pulsatility, distensibility, and pulse wave velocity. Pulse wave velocity decreased (6.3±2.3 m/s to 4.5±1.8 m/s, P<0.001) and pulsatility and distensibility increased (15.9%±5.3% to 22.1%±7.9%, P<0.001; and 0.28%±0.10%/mm Hg to 0.40%±0.14%/mm Hg, P<0.001, respectively) following 6 months of spironolactone.

Conclusions

Our results suggest that spironolactone improves aortic properties in resistant hypertension independently of BP, which may support the hypothesis of an effect of aldosterone on the arterial wall. A larger prospective study is needed to confirm our findings.

Polymeric perfluorocarbon nanoemulsions are ultrasound-activated wireless drug infusion catheters

Catheter-based intra-arterial drug therapies have proven effective for a range of oncologic, neurologic, and cardiovascular applications. However, these procedures are limited by their invasiveness and relatively broad drug spatial distribution. The ideal technique for local pharmacotherapy would be noninvasive and would flexibly deliver a given drug to any region of the body with high spatial and temporal precision. Combining polymeric perfluorocarbon nanoemulsions with existent clinical focused ultrasound systems could in principle meet these needs, but it has not been clear whether these nanoparticles could provide the necessary drug loading, stability, and generalizability across a range of drugs, beyond a few niche applications. Here, we develop polymeric perfluorocarbon nanoemulsions into a generalized platform for ultrasound-targeted delivery of hydrophobic drugs with high potential for clinical translation. We demonstrate that a wide variety of drugs may be effectively uncaged with ultrasound using these nanoparticles, with drug loading increasing with hydrophobicity. We also set the stage for clinical translation by delineating production protocols that are scalable and yield sterile, stable, and optimized ultrasound-activated drug-loaded nanoemulsions. Finally, we exhibit a new potential application of these nanoemulsions for local control of vascular tone. This work establishes the power of polymeric perfluorocarbon nanoemulsions as a clinically-translatable platform for efficacious, noninvasive, and localized ultrasonic drug uncaging for myriad targets in the brain and body.

The effect of continuous positive airway pressure therapy on arterial stiffness and endothelial function in obstructive sleep apnea: a randomized controlled trial in patients without cardiovascular disease

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality which may be mediated by increased arterial stiffness and endothelial dysfunction. Continuous positive airway pressure (CPAP) therapy improves excessive daytime somnolence (EDS), but its effect on vascular function in patients without preexisting cardiovascular disease (CVD) is unclear.

METHODS

Fifty-three patients with OSA defined as an apnea-hypopnea index (AHI) of ⩾15 and without CVD were recruited into a double-blind, randomized, placebo-controlled, crossover trial of 12weeks of CPAP therapy, of whom 43 participants completed the study protocol. Arterial stiffness was assessed by measuring the augmentation index (AIx) and pulse wave velocity (PWV) by applanation tonometry and cardiovascular magnetic resonance imaging to determine aortic distensibility. Endothelial function was assessed by measuring vascular reactivity after administration of salbutamol and glyceryl trinitrate.

RESULTS

CPAP therapy lowered systolic blood pressure (SBP) (126mmHg [standard deviation {SD}, 12] vs 129mmHg [SD, 14]; P=.03), with a trend towards reduced AIx (15.5 [SD, 11.9] vs 16.6 [SD, 11.7]%; P=.08) but did not modify endothelial function. When subjects with (n=24) and without (n=19) EDS were separately examined, no effect of CPAP therapy on vascular function was seen.

CONCLUSIONS

In patients without overt CVD, CPAP therapy had a nonsignificant effect on AIx and did not modify endothelial function.

Vascular function assessed with cardiovascular magnetic resonance predicts survival in patients with advanced chronic kidney disease

BACKGROUND

Increased arterial stiffness is associated with mortality in patients with chronic kidney disease. Cardiovascular magnetic resonance (CMR) permits assessment of the central arteries to measure aortic function.

METHODS

We studied the relationship between central haemodynamics and outcome using CMR in 144 chronic kidney disease patients with estimated glomerular filtration rate <15 ml/min (110 on dialysis). Aortic distensibilty and volumetric arterial strain were calculated from cross sectional aortic volume and pulse pressure measured during the scan.

RESULTS

Median follow up after the scan was 24 months. There were no significant differences in aortic distensibilty or aortic volumetric arterial strain between pre-dialysis and dialysis patients. Aortic distensibilty and volumetric arterial strain negatively correlated with age. Aortic distensibilty and volumetric arterial strain were lower in diabetics, patients with ischaemic heart disease and peripheral vascular disease. During follow up there were 20 deaths. Patients who died had lower aortic distensibilty than survivors. In a survival analysis, diabetes, systolic blood pressure and aortic distensibilty were independent predictors of mortality. There were 12 non-fatal cardiovascular events during follow up. Analysing the combined end point of death or a vascular event, diabetes, aortic distensibilty and volumetric arterial strain were predictors of events.

CONCLUSION

Deranged vascular function measured with CMR correlates with cardiovascular risk factors and predicts outcome. CMR measures of vascular function are potential targets for interventions to reduce cardiovascular risk.

Effect of Angiotensin‐Converting Enzyme Inhibitors on Arterial Stiffness in Hypertension: Systematic Review and Meta‐Analysis

Arterial stiffness is an independent cardiovascular prognostic factor and is modulated by angiotensin-converting enzyme inhibitors (ACEIs). The authors performed a meta-analysis of clinical trials investigating the effects of ACEIs on pulse wave velocity (PWV) or augmentation index. The search included randomized clinical trials as well as uncontrolled studies that measured in-treatment changes in arterial stiffness. The authors performed separate analyses for carotid-femoral PWV, brachioradial PWV, and augmentation index. Average absolute and relative reduction in mean arterial pressure and PWV were -15.4 mm Hg and -13.04% and -1.15 m/s and -9.74% for carotid-femoral PWV studies; and -11.2 mm Hg and -9.3% and -1.9 m/s and -16.7% for brachioradial PWV studies. There was a greater reduction in augmentation index by ACEIs when compared with controls (-1.0% to -5.3%). The authors conclude that ACEIs have modest beneficial effects on arterial stiffness measured as PWV and augmentation index, and this effect is at least partly independent of changes in blood pressure.

Aortic distensibility is closely related to the progression of left ventricular hypertrophy in patients receiving hemodialysis

Aortic stiffening and left ventricular hypertrophy are believed to be major determinants for the prognosis of patients with end-stage renal disease. However, the relationship between left ventricular hypertrophy and aortic stiffness remains to be determined. Echocardiographically determined parameters and aortic distensibility determined with cine magnetic resonance were evaluated in 21 patients undergoing chronic hemodialysis. Hemodynamic variables measured at the beginning of the study were compared with those measured after 28 months. Aortic distensibility determined at the descending aorta was markedly lower in patients undergoing hemodialysis than in healthy control subjects. During the follow-up period, blood pressure and hemodynamic variables, including left ventricular mass index, remained unchanged. However, multiple regression analysis indicated that aortic distensibility independently contributed to the left ventricular mass index and to the change in left ventricular mass index between baseline and after 28 months. Baseline left ventricular mass index negatively correlated to aortic distensibility (r = -0.74, p < 0.0001), and the changes in left ventricular mass index positively correlated to aortic distensibility (r = 0.52, p < 0.05). Our study demonstrates that aortic distensibility at the descending aorta is a predictable marker for the development or regression of left ventricular hypertrophy. Therefore, patients with end-stage renal disease must be treated with appropriate drugs to improve aortic distensibility.