Effects of Different Kinds of Physical Activity on Vascular Function

Regular exercise is one of the main non-pharmacological measures suggested by several guidelines to prevent and treat the development of hypertension and cardiovascular disease through its impact on the vascular system. Routine aerobic training exerts its beneficial effects by means of several mechanisms: decreasing the heart rate and arterial pressure as well as reducing the activation of the sympathetic system and inflammation process without ignoring the important role that it plays in the metabolic profile. Through all these actions, physical training counteracts the arterial stiffening and aging that underlie the development of future cardiovascular events. While the role of aerobic training is undoubted, the effects of resistance training or combined-training exercise on arterial distensibility are still questioned. Moreover, whether different levels of physical activity have a different impact on normotensive and hypertensive subjects is still debated.

Variations in the Second Derivative of a Photoplethysmogram with Age in Healthy Korean Adults

Second derivative of photoplethysmogram (SDPTG) indices correlate with aging and vascular health. The trend of SDPTG indices with age has not yet been studied in the Korean population. Various SDPTG indices were measured in 300 healthy Koreans (150 men and 150 women), aged 19−69 years, stratified into five age groups consisting of 60 people (30 men and 30 women) in each age group from their 20s to 60s. The values of the SDPTG indices clearly showed distinct variations with age in healthy Korean groups (p < 0.001 for all indices). b/a increased linearly with age (y = 0.0045x − 0.803), as did SDPTG aging index (SDPTG-AI) (y = 0.0162x − 1.1389). c/a decreased linearly with age (y = −0.0044x + 0.1017), as did d/a (y = −0.0062x + 0.034) and e/a (y = −0.001x + 0.2002). A significant sex difference was shown in b/a and e/a ratios and SDPTG-AI (p < 0.001 for all indices); women had a higher b/a ratio (−0.55 ± 0.14 versus −0.65 ± 0.13) and SDPTG-AI (−0.33 ± 0.3 versus −0.52 ± 0.33) and a lower e/a ratio (0.13 ± 0.06 versus 0.18 ± 0.07) than men. A linear regression model of diverse SDPTG indices was provided according to the age of healthy Koreans, which may be valuable in preventing diseases related to vascular conditions by estimating the degradation of arterial function.

Non-Invasive Assessment of Arterial Stiffness: Pulse Wave Velocity, Pulse Wave Analysis and Carotid Cross-Sectional Distensibility: Comparison between Methods

Background: The stiffening of large elastic arteries is currently estimated in research and clinical practice by propagative and non-propagative models, as well as parameters derived from aortic pulse waveform analysis. Methods: Common carotid compliance and distensibility were measured by simultaneously recording the diameter and pressure changes during the cardiac cycle. The aortic and upper arm arterial distensibility was estimated by measuring carotid−femoral and carotid−radial pulse wave velocity (PWV), respectively. The augmentation index and blood pressure amplification were derived from the analysis of central pulse waveforms, recorded by applanation tonometry directly from the common carotid artery. Results: 75 volunteers were enrolled in this study (50 females, average age 53.5 years). A significant inverse correlation was found between carotid distensibility and carotid−femoral PWV (r = −0.75; p < 0.001), augmentation index (r = −0.63; p < 0.001) and central pulse pressure (r = −0.59; p < 0.001). A strong correlation was found also between the total slope of the diameter/pressure rate carotid curves and aortic distensibility, quantified from the inverse of the square of carotid−femoral PWV (r = 0.67). No correlation was found between carotid distensibility and carotid−radial PWV. Conclusions: This study showed a close correlation between carotid−femoral PWV, evaluating aortic stiffness by using the propagative method, and local carotid cross-sectional distensibility.

Acute Tachycardia Increases Aortic Distensibility, but Reduces Total Arterial Compliance Up to a Moderate Heart Rate

Background: The differential effects of rapid cardiac pacing on small and large vessels have not been well-established. The objective of this study was to investigate the effect of pacing-induced acute tachycardia on hemodynamics and arterial stiffness.

Methods: The pressure and flow waves in ascending aorta and femoral artery of six domestic swine were recorded simultaneously at baseline and heart rates (HR) of 135 and 155 beats per minutes (bpm) and analyzed by the models of Windkessel and Womersley types. Accordingly, the flow waves were simultaneously measured at carotid and femoral arteries to quantify aortic pulse wave velocity (PWV). The arterial distensibility was identified in small branches of coronary, carotid and femoral arteries with diameters of 300–600 μm by ex vivo experiments.

Results: The rapid pacing in HR up to 135 bpm reduced the total arterial compliance, stroke volume, systemic pulse pressure, and central systolic pressure by 36 ± 17, 38 ± 26, 29 ± 16, and 23 ± 12%, respectively, despite no statistical difference of mean aortic pressure, cardiac output, peripheral resistance, and vascular flow patterns. The pacing also resulted in a decrease of distensibility of small muscular arteries, but an increase of aortic distensibility. Pacing from 135 to 155 bpm had negligible effects on systemic and local hemodynamics and arterial stiffness.

Conclusions: There is an acute mismatch in the response of aorta and small arteries to pacing from basal HR to 135 bpm, which may have important pathological implications under chronic tachycardia conditions.

Noninvasive assessment of the common carotid artery hemodynamics with increasing exercise work rate using wave intensity analysis

Noninvasively determined local wave speed (c) and wave intensity (WI) parameters provide insights into arterial stiffness and cardiac-vascular interactions in response to physiological perturbations. However, the effects of incremental exercise and subsequent recovery on c and WI have not been fully established. We examined the changes in c and WI parameters in the common carotid artery (CCA) during exercise and recovery in eight young, healthy male athletes. Ultrasound measurements of CCA diameter and blood flow velocity were acquired at rest, during five stages of incremental exercise (up to 70% maximum work rate), and throughout 1 h of recovery, and noninvasive WI analysis [diameter-velocity (DU) approach] was performed. During exercise, c increased (+136%), showing increased stiffness with work rate. All peak and area of forward compression, backward compression, and forward expansion waves increased during exercise (+452%, +700%, and +900%, respectively). However, WI reflection indexes and CCA resistance did not significantly change from rest to exercise. Furthermore, wave speed and the magnitude of all waves returned to baseline within 5 min of recovery, suggesting that the effects of exercise in the investigated parameters of young, healthy individuals were transient. In conclusion, incremental exercise was associated with an increase in local CCA stiffness and increases in all wave parameters, indicative of enhanced ventricular contractility and improved late-systolic blood flow deceleration.

NEW & NOTEWORTHY We examined hemodynamics of the common carotid artery using noninvasive application of wave intensity analysis during exercise and recovery. The hemodynamic adjustments to exercise were associated with increases in local common carotid artery stiffness and all waves’ parameters, with the latter indicating enhanced ventricular contractility and improved late systolic blood flow deceleration.

Resistance training-induced decrease in central arterial compliance is associated with decreased subendocardial viability ratio in healthy young men

High-intensity resistance training decreases central arterial compliance (CAC). Subendocardial viability ratio (SEVR) is a useful tool that reflects the balance between coronary perfusion and left ventricular afterload. Animal studies have demonstrated that decreased CAC is associated with SEVR deterioration. Therefore, resistance training-induced decrease in CAC may be associated with changes in SEVR. The objective of the present study was to investigate the association between SEVR and CAC using both cross-sectional and longitudinal (i.e., resistance training) study designs. To achieve this, we first conducted a cross-sectional study to investigate the association between SEVR and CAC in 89 young men. Thereafter, a longitudinal study was performed to examine the effects of resistance training on SEVR and CAC in young men. A total of 28 young men were divided into 2 groups: control (n = 13) and training (n = 15). In the training group, subjects underwent supervised resistance training for 4 weeks (5 sets of 10 repetitions at 75% of 1-repetition maximum, 3 times/week). CAC and SEVR were then measured in all subjects. In the cross-sectional study, SEVR was significantly positively correlated with CAC, whereas resistance training significantly decreased both SEVR and CAC. Moreover, training-induced changes in CAC were significantly correlated with changes in SEVR. Thus, these results suggest that resistance training-induced decrease in CAC is associated with decreased SEVR in young men.

Relationship between serum homocysteine levels and structural-functional carotid arterial abnormalities in inactive Behçet's disease

BACKGROUND

Behçet's disease (BD) is a chronic autoimmune disorder with symptoms manifesting from an underlying vasculitis. Since the disease activity is correlated with characteristic vascular endothelial dysfunction, BD places individuals at increased risk of cardiovascular diseases, such as atherosclerosis. Hyperhomocysteinaemia is an independent risk factor for arteriosclerotic vascular diseases.

AIM

This study was designed to investigate how plasma homocysteine (Hcy) affects the structural and functional properties of the carotid artery in humans.

METHODS

Sixty-eight BD patients with subclinical atherosclerosis and 40 healthy controls underwent carotid sonography and Doppler ultrasound to measure carotid artery intima-media thickness (C-IMT) and carotid stiffness and distensibility (indicat-ing elasticity). Total Hcy level was determined by enzyme-linked immunosorbent assay. For analysis, the BD patients were sub-grouped according to hyperhomocysteinaemia (> 15 μmol/L).

RESULTS

The patients with BD were found to have increased C-IMT and beta stiffness and decreased distensibility. In addition, hyperhomocysteinaemia was significantly correlated with these detrimental changes in the carotid artery, possibly raising the risk of these patients developing atherosclerosis.

CONCLUSIONS

These findings suggest a potential mechanism of atherosclerosis in BD and highlight the processes that future research should focus on to address identification and prophylactic treatment of BD patients at risk of cardiovascular disease.

Ambulatory Aortic Stiffness Is Associated With Narrow Retinal Arteriolar Caliber in Hypertensives: The SAFAR Study

BACKGROUND

Arterial stiffness measured under static conditions reclassifies significantly cardiovascular (CV) risk and associates with narrower retinal arterioles. However, arterial stiffness exhibits circadian variation, thus single static stiffness recordings do not correspond to the "usual" 24 hr, awake, and asleep average arterial stiffness. We aimed to test the hypothesis that ambulatory 24 hr, awake, and asleep aortic (a) pulse wave velocity (PWV) associate with retinal vessel calibers, independently of confounders and of static arterial stiffness, in hypertensive individuals free from diabetes and CV disease.

METHODS

Digital retinal images were obtained (181 individuals, age: 53.9±10.7 years, 55.2% men) and retinal vessel calibers were measured with validated software to determine central retinal arteriolar and venular equivalents (CRAE and CRVE, respectively); ambulatory (24 hr, awake, asleep) and static office aPWV were estimated by Mobil-O-Graph; and static office carotid to femoral (cf) PWV by SphygmoCor.

RESULTS

Regression analysis performed in 320 gradable retinal images showed that, after adjustment for confounders: (i) ambulatory aPWV was significantly associated with narrower retinal arterioles but not with venules; (ii) asleep aPWV had stronger associations with CRAE than awake aPWV; (iii) both ambulatory aPWV and cfPWV were associated mutually independently with narrower retinal arterioles; aPWV introduction in the model of cfPWV, improved model's R2 (P = 0.012). Similar discriminatory ability of 24 hr aPWV and of cfPWV to detect the presence of retinal arteriolar narrowing was found.

CONCLUSION

Ambulatory aPWV, estimated by an operator-independent method, provides additional information to cfPWV regarding the associations of arterial stiffness with the retinal vessel calibers.

Large artery stiffening with weight gain in humans: role of visceral fat accumulation

We tested the hypothesis that weight gain would increase arterial stiffness in healthy nonobese adults. To address this, we overfed 14 nonobese men (age: 23+/-1 years) approximately 1000 kcal/d for 6 to 8 weeks until a 5-kg weight gain was achieved. Carotid diameters (high-resolution ultrasound) and pressures (applanation tonometry), body composition (dual energy x-ray absorptiometry), and abdominal fat distribution (computed tomography) were measured at baseline and following 4 weeks of weight stability at each individual's elevated body weight. Overfeeding increased body weight 5.1+/-0.1 kg and body fat 3.4+/-0.4 kg (both P<0.001) in 45+/-7 days. Total abdominal fat increased 46+/-7 cm(2) with weight gain due to increases in both subcutaneous (30+/-6 cm(2)) and visceral fat (15+/-4 cm(2); all P<0.01). As hypothesized, weight gain increased arterial stiffness 13+/-6% and decreased arterial compliance 21+/-4% (both P<0.05). Furthermore, those individuals above the median increase in abdominal visceral fat demonstrated a significantly greater increase in arterial stiffness (0.97+/-0.29 versus 0.06+/-0.36 U; P<0.05) compared with those below the median. Consistent with these observations, the only correlates of the changes in arterial stiffness with weight gain were the increases in total abdominal fat (r=0.794), abdominal visceral fat (r=0.651), and waist circumference (r=0.470; all P<0.05). Taken together, these findings suggest that modest weight gain is associated with increases arterial stiffness in nonobese men. The degree of large artery stiffening with weight gain seems to be determined, in part, by the amount of abdominal visceral fat gain. Importantly, this relation is independent of the amount of total body fat gained.

Comparison of the micro- and macro-vascular effects of glimepiride and gliclazide in metformin-treated patients with Type 2 diabetes: a double-blind, crossover study

AIMS

To compare the metabolic and vascular effects of two sulphonylureas (SU), gliclazide (specific for the pancreatic [SUR1] receptor) and glimepiride (a nonspecific agent that also binds to vascular and cardiac [SUR2] receptors), during chronic administration in metformin-treated patients with Type 2 diabetes (T2DM).

METHODS

A randomized, double-blind, crossover study of gliclazide 80 mg BID and glimepiride 2 mg OD, each for 4 weeks as add-on therapy to metformin, with a 4-week washout period. Patients attended four study mornings after first dose and 4 weeks' SU treatment for measurements of arterial distensibility (Ax), pressor responsiveness to i.v. angiotensin II (ANGII), and cutaneous microvascular vasodilator responses to iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP).

RESULTS

Glycaemic responses were similar (e.g. serum fructosamine was 315 vs 329 micro mol l-1 after 4 weeks), and there was no change in augmentation index during treatment with either SU (9.1 vs 9.8 mmHg after 4 weeks [95% confidence interval -8.1, 10.5]). Similarly, there were no differences between treatments in pressor responsiveness (e.g. PD10[dose of agonist required to increase mean BP by 10 mmHg] for ANGII was 1.37 vs 1.68 ng kg-1 min-1[-4.3, 6.9]) or cutaneous microvascular vasodilator responses (peak ACh response 68 +/- 36 vs 63 +/- 34 perfusion units [-82.7, 79.1]).

CONCLUSIONS

There is no evidence that SUR1-specific and nonspecific SUs have differential effects on arterial distensibility, endothelial function or vasodilator mechanisms in metformin-treated patients with T2DM.