Pathological Pulse Wave Latency as a Surrogate of Sympathetic Adrenergic Failure in Patients with Idiopathic and Atypical Parkinson Syndromes

Autonomic dysfunction is associated with idiopathic Parkinson's disease (IPS) and atypical Parkinson syndromes (APS) like multiple system atrophy (MSA). One approach to obtain quantitative information about the status of orthostatic hypotension, in which sympathetic adrenergic failure may be predominant, is to measure blood pressure response to active standing up or tilting after supine rest. However, continuous recording of blood pressure using commercial blood pressure monitors requires special equipment available only in specialized centers. We used the pulse wave latency (PWL) as a surrogate of beat-to-beat blood pressure. The PWL was calculated by the interval between the R wave of the ECG and the blood pressure pulse, which was recorded at the right earlobe by a photoplethysmographic device. It has been shown previously that changes of the PWL are negatively correlated to the changes of intra-arterial blood pressure recording with an almost perfect linear fit. The measurement of heart rate variability (HRV) to assess parasympathetic autonomic function is clinically routine in most autonomic labs. We used the device FAN ® (Schwarzer, Germany) which allows the recording of PWL and HRV at the same time. In 22 patients with Parkinson syndromes (IPS and APS) and 89 healthy controls we recorded PWL differences and HRV before and after Valsalva maneuver (VM), focusing on phase IV, the blood pressure overshoot. Our patients with Parkinson syndromes showed significantly (p=0.002) different results in terms of reduced PWL reduction after VM compared to controls. Concerning HRV only the coefficients of variation during deep respiration (p=0.004) and at rest (p=0.032) were found to be statistically significantly different in patients with Parkinson syndromes as compared to controls. The measurement of PWL reduction after VM seems to detect pathology of the sympathetic adrenergic nervous system in patients with Parkinson syndromes.