Antihypertensive Treatment and Central Arterial Hemodynamics: A Meta-Analysis of Randomized Controlled Trials

Background: Antihypertensive treatment may have different effects on central arterial hemodynamics. The extent of the difference in effects between various antihypertensive drugs remains undefined.Methods: We conducted a systematic review and meta-analysis of randomized controlled trials that explored the effects of antihypertensive agents on both central and peripheral systolic blood pressure (SBP) and pulse pressure (PP) or central augmentation index, with a special focus on the comparison between newer [renin-angiotensin-aldosterone system (RAS) inhibitors and calcium-channel blockers (CCBs)] and older antihypertensive agents (diuretics and β- and α-blockers).Results: In total, 20 studies (n = 2,498) were included. Compared with diuretics (10 studies), β-blockers (16 studies), or an α-blocker (1 study), RAS inhibitors (21 studies), and CCBs (6 studies) more efficaciously (P < 0.001) reduced both central and peripheral SBP by a weighted mean difference of −5.63 (−6.50 to −4.76 mmHg) and −1.97 mmHg (−2.99 to −0.95 mmHg), respectively. Compared with older agents, the newer agents also more efficaciously (P < 0.001) reduced central PP (−3.27 mmHg; −4.95 to −1.59 mmHg), augmentation index (−6.11%; −7.94 to −4.29) and augmentation (−3.35 mmHg; −5.28 to –1.42 mmHg) but not peripheral PP (p ≥ 0.09). Accordingly, the newer agents reduced central-to-peripheral PP amplification significantly less than the older agents (0.11 mmHg; 0.05 to 0.17 mmHg; P < 0.001).Conclusion: Newer agents, such as RAS inhibitors and CCBs, were significantly more efficacious than older agents in their effects on central hemodynamics.

P.192 Arterial Hemodynamics and the Clinical Presentation of Cerebral Arteriovenous Malformations

Background: Arterial Hemodynamics have been implicated in hemorrhage from cerebral arteriovenous malformations (AVMs). The correlation between hemodynamic characteristics and the tendency of AVMs to rupture has been explored in the past, and various theories have been proposed to explain the clinical presentation of AVMs as a hemorrhage vs. seizure. Methods: We monitored feeder artery pressures in 45 patients with AVMS (16 presenting with hemorrhage, 29 without) during super selective angiography and AVM embolization. Results: Mean feeder artery pressure (FP) was found to be 49mm Hg. The mean FP in patients presenting with hemorrhage was somewhat higher than in those without hemorrhage, but the difference was not statistically significant (53.8 mm Hg vs 47.0 mm Hg, p=0.13). Systemic mean pressure was found to correlate with AVM size (r=-0.31, p=0.037). Significant predictors of feeder artery pressure were systemic pressure, AVM size, and the distance of microcatheter from the circle of Willis. Meanwhile, the presence or absence of venous outflow stenosis and the position of the AVM nidus (superficial or deep to the cortical surface) were the most significant predictors of AVM hemorrhage vs seizures. Conclusions: Anatomic factors may be more important than arterial hemodynamic factors in determining the clinical presentation of cerebral AVMs.

A compact in vitro test bench for cardiovascular flow analysis

A low-cost particle image velocimetry set-up that allows to investigate the fluid dynamics inside realistic coronary artery phantoms has been implemented. The proposed smart test bench for experimental characterization of arterial hemodynamics also in the presence of implanted devices represents a low-cost equipment that can be easily implemented in non-expert laboratories for research as well as educational applications.

Influence of Electroacupuncture on Acupoints of Yanglingquan (GB34) on Gallbladder Volume and Gallbladder Arterial Hemodynamics in Patients With Chronic Cholecystitis

Introduction: In China, patients with chronic cholecystitis account for approximately 10% of the total population, in which over 90% of cholecystitis is caused by cholelithiasis. This study aimed to discuss the possible mechanism of electroacupuncture on the Yanglingquan acupoint promoting gallbladder contractibility of patients with chronic cholecystitis. Methods: 60 patients were randomly divided into a trial group and a control group. Doppler ultrasound and color Doppler blood flow imaging was applied. The trial group adopted the BT701-1B electroanesthesia apparatus to perform electroacupuncture on the bilateral acupoints of Yanglingquan, while electroacupuncture was made on sham acupoints in the control group. Results: Before the electroacupuncture, gallbladder volume was 49.6 ± 5.66 ml, after 15 min and 30 min of electroacupuncture, the gallbladder volume was then 32.9 ± 5.66 ml and 23.0 ± 2.83 ml respectively. The comparison before and after electroacupuncture was obviously and statistically different (P < 0.01). The comparison between after 15 min and 30 min is obviously statistically different (P < 0.01). Before the electroacupuncture, the gallbladder artery Vmax, Vmin, and RI were 18.4 ± 2.69 cm/s, 9.7 ± 0.07 cm/s, and 0.47 ± 0.06, respectively; the cystic artery Vmax, Vmin, and RI after 30 min were 8.1 ± 0.92 cm/s, 3.1 ± 0.57 cm/s, and 0.61 ± 0.02. The comparison in gallbladder artery Vmax and Vmin and the drag index (RI) before and after electroacupuncture was obviously and statistically different (P < 0.01). Conclusions: Electroacupuncture on the acupoints of Yanglingquan has the potential to promote the emptying of the gallbladder. The mechanism may be related to that the smooth muscle of the gallbladder contracts after electroacupuncture and the gallbladder empties.

The effect of left ventricular contractility on arterial hemodynamics: A model-based investigation

Ventricular-arterial coupling is a major determinant of cardiovascular performance, however, there are still inherent difficulties in distinguishing ventricular from vascular effects on arterial pulse phenotypes. In the present study, we employed an extensive mathematical model of the cardiovascular system to investigate how sole changes in cardiac contractility might affect hemodynamics. We simulated two physiologically relevant cases of high and low contractility by altering the end-systolic elastance, Ees, (3 versus 1 mmHg/mL) under constant cardiac output and afterload, and subsequently performed pulse wave analysis and wave separation. The aortic forward pressure wave component was steeper for high Ees, which led to the change of the total pressure waveform from the characteristic Type A phenotype to Type C, and the decrease in augmentation index, AIx (-2.4% versus +18.1%). Additionally, the increase in Ees caused the pulse pressure amplification from the aorta to the radial artery to rise drastically (1.86 versus 1.39). Our results show that an increase in cardiac contractility alone, with no concomitant change in arterial properties, alters the shape of the forward pressure wave, which, consequently, changes central and peripheral pulse phenotypes. Indices based on the pressure waveform, like AIx, cannot be assumed to reflect only arterial properties.

Numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation

Background The effects of arterial wall compliance on blood flow have been revealed using fluid-structure interaction in last decades. However, microcirculation is not considered in previous researches. In fact, microcirculation plays a key role in regulating blood flow. Therefore, it is very necessary to involve microcirculation in arterial hemodynamics. Objective The main purpose of the present study is to investigate how wall compliance affects the flow characteristics and to establish the comparisons of these flow variables with rigid wall when microcirculation is considered. Methods We present numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation. A novel outlet boundary condition is employed to prescribe microcirculation in an idealised model. Results The novel finding in this work is that wall compliance under the consideration of microcirculation leads to the increase of wall shear stress in contrast to rigid wall, contrary to the traditional result that wall compliance makes wall shear stress decrease when a constant or time dependent pressure is specified at an outlet. Conclusions This work provides the valuable study of hemodynamics under physiological and realistic boundary conditions and proves that wall compliance may have a positive impact on wall shear stress based on this model. This methodology in this paper could be used in real model simulations.