Sympathetic cardiovascular dysfunction in long-standing idiopathic Parkinson's disease.

Standard autonomic tests (heart rate response to deep breathing--HRDB, heart rate and systolic blood pressure response to tilt--delta HR and delta SBP) and spectral analysis of heart rate and arterial blood pressure and their transfer function (for the mid-frequency band a measure of baroreflex sensitivity) were performed in 20 patients with idiopathic Parkinson's disease (IPD) and 20 age-matched controls. Patients showed significantly diminished delta SBP, and reduced sympathetic vasomotor and cardiomotor outflow (diminished Mayer waves), consistent with an alteration of the efferent arc of the baroreflex. These results were only significant in long-standing IPD (IPD-l, > 5 years), whereas patients with short disease duration (IPD-s, < 5 years) showed values comparable to controls. Respiratory-related heart rate variability was slightly reduced in IPD-1 but this was mainly due to diminished respiratory effort, indicated by low respiratory-related blood pressure variability. We conclude that autonomic abnormalities are only present in long-standing IPD and consist in reduced sympathetic vasomotor and cardiomotor outflow.