Cardiocirculatory manifestations in Parkinson's disease patients without orthostatic hypotension

The objective of this study was to characterize cardiac sympathetic denervation in Parkinson's disease (PD) patients without neurogenic orthostatic hypotension (NOH), both in terms of hemodynamics and in its relation with vascular denervation. We studied 20 PD patients without NOH. We analyzed the heart rate and blood pressure variability during various physical maneuvers. The following parameters were calculated: expiratory-inspiratory ratio, stroke volume, cardiac output, cardiac index, left ventricular ejection time, left ventricular work index, thoracic fluid content, total peripheral resistance and baroreflex sensitivity (BRS). We also measured direct and spectral derivatives of cardiac (cardiovagal) parasympathetic function. Myocardial I-123 metaiodobenzylguanidine (MIBG) scintigraphy was performed and early and late heart/mediastinum uptake ratios were analyzed. We observed that the late heart/mediastinum uptake ratio was 1.33±0.21. This parameter was correlated with years since diagnosis (correlation coefficient:−0.485; P=0.05), Unified Parkinson’s Disease Rating Scale (UPDRS) III score (cc:−0.564; P=0.02) and pressure recovery time in the Valsalva maneuver (cc: 0.61; P<0.001). At rest, it was correlated with BRS (cc:0.75; P=0.003) and low-frequency diastolic blood pressure (LFDBP; cc: 0.58;P=0.017). We found no correlations with any of the cardiography impedance variables. In linear regression models, the variable that best correlated with MIBG results was LFDBP. Our results support that in absence of NOH the degree of denervation of the heart does not produce any effect on its inotropic function. Moreover, BRS and LFDBP can be used as an indirect measure of cardiac sympathetic denervation at rest.