Relationships between autonomic function and 24-hour blood pressure profile in patients with primary biliary cirrhosis

Introduction: In order to further clarify the supposed connection between the systemic hypotension – characterizing hyperdynamic circulation – and the autonomic function, we aimed to evaluate the relationship between autonomic function and 24-hour blood pressure profile in patients with primary biliary cirrhosis.

Patients and methods: Twenty-four AMA M2 positive female patients with PBC and twenty age-matched healthy female subjects were studied. Five standard cardiovascular reflex-tests and 24-hour heart rate variability (HRV) analysis were performed to define autonomic function.

Results: Using standard cardiovascular reflex-tests, 14 patients with PBC (58%) had autonomic neuropathy. Each patient had at least one abnormal parameter of HRV. In patients with PBC significantly lower 24-hour mean systolic and diastolic blood pressure values were found than in control subjects (116/69 vs. 124/75mmHg; both P=0.01). Decreased HRV was associated with lower casual blood pressure values in PBC patients. Patients with lower HRV triangular index had lower 24-hour mean systolic (r=0.74; P=0.002) and diastolic (r=0.55; P=0.036) blood pressure values. The severity of autonomic dysfunction was inversely related to 24-hour mean systolic (r=-0.63; P=0.01) and diastolic (r=-0.57; P=0.03) blood pressure values. Time domain parameters of HRV positively correlated with 24-hour blood pressure variability, characterized by 24-hour systolic (r=0.74; P=0.002) and diastolic blood pressure (r=0.79; P=0.0001) standard deviations. Conclusions: The sympatho-vagal imbalance is significantly related to the reduction of casual, and 24-hour mean blood pressure, as well as to lower blood pressure variability. These observations indicate that that autonomic dysfunction may be responsible for systemic hypotension, a typical symptom of hyperdinamic circulation.