Pulsatile stress in middle-aged patients with type 1 or type 2 diabetes compared with nondiabetic control subjects

Cardiovascular Responses to Squatting Postural Stress among Non-Diabetic and Type-2 Diabetic Nigerian Black Africans

Background

A change in posture brings about a significant alteration in cardiovascular functions. The squat test has been used to study autonomic function in White Europeans but not Black Africans. The aim of this study is to determine the cardiovascular effects of postural stress in Black African non-diabetics and Type-2 diabetics.

Method

Blood pressure (BP) and heart rate (HR) was measured in 40 non-diabetics and 40Type-2 diabetics in sitting, standing from sitting, squatting and standing from squatting positions Difference in BP and HR between consecutive positions was tested using 2- way mixed ANOVA. Proportions of those who showed orthostatic hypotension and hypertension were compared with Fishers exact test. Significance was set at p <0.05.

mmHg Δ

BP and HR changes evoked by standing from sitting were not different, however squatting evoked greater increase in BP in diabetics(change (Δ) SBP: 5.85±9.95 vs 17.40±13.75mmHg: Δ DBP: 0.15 ± 6.89 vs 5.10 ± 7.59 mmHg:Δ MABP:2.02 ± 6.98 vs 8.63 ± 9.34 mmHg ,p <0.05) and standing from squatting evoked greater fall BP in diabetics (ΔSBP: -9.80±13.89 vs -24.35±16.03 mmHg; Δ MABP:-2.02±6.98 vs -8.63±9.34 mmHg: Δ PP: -2.28 ±15.35 vs -14.50 ±11.96 mmHg, p < 0.05) while Δ HR did not differ. A higher proportion of diabetics showed SBP and DBP orthostatic hypertension.

Conclusion

Relative to the non-diabetics, diabetics showed greater BP but not HR responses to postural stress.

The relationship between hepatic fibrosis and arterial stiffness in hemodialysis patients

INTRODUCTION

The main cause of death in hemodialysis patients is cardiovascular diseases. Increased arterial stiffness is a predictor of cardiovascular events for hemodialysis patients. Among the nondialysis patient population, arterial stiffness increases in those with hepatic fibrosis and nonalcoholic fatty liver disease. This study aims to examine the relationship between hepatic fibrosis and arterial stiffness in hemodialysis patients for the first time in the literature.

MATERIAL AND METHOD

The study includes chronic hemodialysis patients over 18 years of age who had been treated for hemodialysis for at least 6 months. Patients with chronic liver disease, chronic viral hepatitis (HBV and HCV), alcohol use, or liver disease accompanied by polycystic kidney disease and active infection were excluded. Hepatic fibrosis scores were measured using the FibroScan device. Single-cuff Mobil-o-Graph was used for measurement of arterial stiffness.

RESULTS

Fifty-nine patients were enrolled; 54.2% of the patients were male, and the mean age was 53.9 ± 12.9 years. Thirty-nine percent of the patients had diabetes. Average pulse wave velocity (PWV) value of the patients was 8.3 ± 1.6 m/s, and it had positive correlation with age, CAP score, fibrosis score, and body mass index and showed negative correlation to albumin. It was seen that the patients with a PWV value ≥ 10 m/s have significantly higher CAP score compared with the patients with a PWV < 10 m/s. When the factors predicting PWV were examined in the regression analysis, age and systolic blood pressure were found to be determinants.

CONCLUSION

Increased hepatic fibrosis in hemodialysis patients is associated with increased arterial stiffness, but this relationship is not independent.

Squatting, a posture test for studying cardiovascular autonomic neuropathy in diabetes

Cardiovascular autonomic neuropathy (CAN) is a frequent complication of diabetes mellitus, which is associated with increased morbidity and mortality. It involves both the parasympathetic and sympathetic nervous systems, and may be diagnosed by classical dynamic tests with measurements of heart rate (HR) and/or arterial blood pressure (BP). An original squat test (1-min standing, 1-min squatting, 1-min standing) was used with continuous monitoring of HR and BP, using a Finapres(®) device. This active test imposes greater postural stress than the passive head-up tilt test, and provokes large changes in BP and HR that can be analyzed to derive indices of CAN. In healthy subjects, squatting is associated with BP increases and HR decreases (abolished by atropine: SqTv index), whereas the squat-stand transition is accompanied by a deep but transient drop in BP associated with sympathetic-driven tachycardia (abolished by propranolol: SqTs index). In diabetic patients with CAN, BP increases are accentuated during squatting whereas reflex bradycardia is reduced. When standing from squatting position, the fall in BP tends to be more pronounced and orthostatic hypotension more prolonged, while reflex tachycardia is markedly dampened. The baroreflex gain, similar to that calculated during pharmacological testing with vasodilator/vasopressor agents, can be derived by plotting pulse intervals (R-R) against systolic BP levels during the biphasic response following the squat-stand transition. The slope, which represents baroreflex sensitivity, is significantly reduced in patients with CAN. This discriminatory index allows study of the natural history of CAN in a large cohort of diabetic patients.