Reduced neural baroreflex sensitivity is related to enhanced endothelial function in patients with end-stage liver disease

Peripheral endothelial and microvascular damage in liver cirrhosis: a systematic review and meta-analysis

OBJECTIVE

This is the first systematic review and meta-analysis of studies using any available functional method to examine differences in peripheral endothelial function between cirrhotic and non-cirrhotic individuals.

METHODS

Literature search involved PubMed, Web-of-Science and Scopus databases, as well as grey literature sources. We included studies in adult subjects evaluating endothelial function with any semi-invasive or non-invasive functional method in patients with and without liver cirrhosis.

RESULTS

From 3378 records initially retrieved, 15 studies with a total of 570 participants were included in the final quantitative meta-analysis. In 6 studies examining endothelial function with flow-mediated-dilatation no differences between patients with cirrhosis and controls were evident (WMD: 1.33, 95%CI [-2.87, 5.53], I² =97%, p<0.00001). Among studies assessing differences in endothelial-dependent or endothelial-independent vasodilation with venous-occlusion-plethysmography, there were no significant differences between the two groups. When pooling all studies together, regardless of the technique used, no significant difference in endothelial function between cirrhotic patients and controls was observed(SMD: 0.79, 95%CI[-0.04, 1.63], I2=94%, p<0.00001).

CONCLUSIONS

No differences in peripheral endothelial function assessed with semi-invasive or non-invasive functional methods exist between cirrhotic and non-cirrhotic subjects. The increasing co-existence of cardiovascular risk factors leading to impaired vascular reactivity in cirrhotic patients may partly explain these findings.

Type 2 Diabetes Mellitus Is Independently Associated With Decreased Neural Baroreflex Sensitivity: The Paris Prospective Study III

OBJECTIVE

Impaired baroreflex function is an early indicator of cardiovascular autonomic imbalance. Patients with type 2 diabetes mellitus (T2D) have decreased baroreflex sensitivity (BRS), however, whether the neural BRS (nBRS) and mechanical component of the BRS is altered in those with high metabolic risk (HMR, impaired fasting glucose and metabolic syndrome) or with overt T2D, is unknown. We examined this in a community-based observational study, the Paris Prospective Study III (PPS3). Approach and Results: In 7626 adults aged 50 to 75 years, resting nBRS (estimated by low-frequency gain, from carotid distension rate and RR [time elapsed between two successive R waves] intervals) and mechanical BRS were measured by high-precision carotid echotracking. The associations between overt T2D or HMR as compared with subjects with normal glucose metabolism and nBRS or mechanical BRS were quantified using multivariable linear regression analysis. There were 319 subjects with T2D (61±6 years, 77% male), 1450 subjects with HMR (60±6 years, 72% male), and 5857 subjects with normal glucose metabolism (59±6 years, 57% male). Compared with normal glucose metabolism, nBRS was significantly lower in HMR subjects (β=-0.07 [95% CI, -0.12 to -0.01]; P=0.029) and in subjects with T2D (β=-0.18 [95% CI, -0.29 to -0.07]; P=0.002) after adjustment for confounding and mediating factors. Subgroup analysis suggests significant and independent alteration in mechanical BRS only among HMR patients who had both impaired fasting glucose and metabolic syndrome.

CONCLUSIONS

In this community-based study of individuals aged 50 to 75, a graded decrease in nBRS was observed in HMR subjects and patients with overt T2D as compared with normal glucose metabolism subjects.

Acute hypotension attenuates brachial flow-mediated dilation in young healthy men

PURPOSE

This study aimed to test our hypothesis that acute hypotension attenuates brachial flow-mediated dilation (FMD) as an index of endothelial function in healthy humans.

METHODS

Twelve healthy men (21.8 ± 1.6 years, body mass index; 22.2 ± 1.6 kg/m²) participated in this study. Brachial FMD was measured in three trials: standardized FMD protocol (control trial), abrupt decrease in blood pressure (BP) via thigh cuff inflation-deflation (hypotension trial) and decrease in shear rate (SR) via a shortened forearm occlusion time (SR reduction trial). Brachial diameter and blood velocity were measured using Duplex ultrasound.

RESULTS

Mean arterial pressure during reactive hyperaemia showed a marked decrease in the hypotension trial (- 23.7 ± 6.0 mmHg), but not in the control and SR reduction trials. SR area under the curve was attenuated in the SR reduction trial (P < 0.001), but not in the control and hypotension trials (P = 0.316). Consequently, FMD was attenuated in the hypotension and SR reduction trials compared with that in the control trial (P = 0.003 and P = 0.043, respectively), and was attenuated to a greater extent in the hypotension trial compared with the SR reduction trial (P = 0.006; control, 6.9 ± 3.5%; hypotension, 3.5 ± 1.7%; SR reduction, 5.0 ± 2.2%). After adjusting FMD using SR, FMD remained attenuated in the hypotension trial (P = 0.014), but not in the SR reduction trial.

CONCLUSION

Our findings indicate that arterial pressure as well as sympathetic nervous system activation could be an important determinant of FMD. Blunted FMD of peripheral arteries may be a rational response to restore BP and/or prevent further reduction of BP following acute hypotension in healthy humans.