Cardiovascular Reflexes in Parkinsonism

Abstract

1. Cardiovascular reflex activity has been studied in thirty Parkinsonian patients, none of who had received levodopa or sympatholytic drugs.2. Changes in blood pressure and pulse rate in response to Valsalva's manoeuvre and head-up tilt were investigated by intra-arterial recording.3. Cardiovascular reflexfunction deteriorated with advancing age, but there was no correlation with either the duration or the severity of the Parkinsonism.4. These results are discussed in relation to previous reports of hypotension in Parkinsonism.Numerous therapeutic successes and several important adverse reactions have followed the adoption of levodopa (t-dopa) as treatment for Parkinsonism. The frequent occurrence of orthostatic hypotension as a reversible, dose-dependent effect of levodopa therapy has led to a resurgence of interest in the mechanisms of blood-pressure control in these patients. It has been reported that the blood pressure is lower than normal in Parkinsonism irrespective of drug administration and there have been suggestions of a generalized defect of catecholamine metabolism (Barbeau, 1970). More recently it has been found that plasma renin activity is decreased (Barbeau, Gillo-Joffroy, Boucher, Nowaczynski & Genest, 1969;Michelakis & Robertson, 1970). Shy & Drager (1960) have described six patients who presented with autonomic dysfunction including orthostatic hypotension and subsequently developed some of the clinical features of Parkinsonism.To obtain further information on the control of blood pressure in Parkinsonian patients before administration of levodopa, we have studied the cardiovascular response to Valsalva's manoeuvre and to head-up tilt. MATERIALSPatients. Thirty patients were investigated, of these twenty-eight had idiopathic and two postencephalitic Parkinsonism. There were fifteen men and fifteen women, their ages ranging

Cardiovascular Reflexes in Parkinson’s Disease

“…Our results agree very well with these earlier findings but disagree with both those of Aminoff and Wilcox [7], who have reported intact cardio vascular reflexes in their series of 11 patients with PD, and with those of Reid et al [8] and Gross et al [4], who did not find any differ ence in the pulse rate as a response to the Valsalva manoeuvre. This discrepancy is possibly at least partially due to the dissimi lar or differently selected clinical patients.…”

“…Conflicting results have been reported in earlier studies concerning cardiovascular re flexes in PD [2,4,[7][8][9]. Because the results of these studies are based on a small number of patients, the present study was under taken firstly to obtain further information on the occurrence and severity of the ANS fail ure in PD by using cardiovascular reflexes and secondly to ascertain the clinical corre lates of these abnormalities.…”

Assessment of selective β‐adrenoceptor blockade in man

“…Through this line arterial blood pressure was monitored with a transducer (Bell & Howell) and, by differentiating the signal electrically, axillary artery dP/dt was derived and was used as a measure of cardiac contractility. The evidence that this parameter gives a measure of cardiac contractility is derived from observations in normal man, Parkinsonian patients (Reid, Calne, George, Pallis & Vakil, 1971;Reid, Calne, George & Vakil, 1972) and anaesthetized dog and is as follows: (a) The increase in dP/dt after i.v. isoprenaline and stellate ganglion stimulation is specifically and reversibly antagonized by ,3-adrenoceptor blockade ( Figure 2).…”

Autonomic nervous system dysfunction in Parkinson’s disease

“…Meco et al [87] reported a reduced Valsalva ratio in PD patients before and after therapy, but the difference was significant compared with control groups before therapy only. Additional studies reported changes in the Valsalva reflex in parkinsonian patients [13,59], although these differences were not confirmed in other reports [89]. The discrepancies between study results may be because of variations in patient selection, study design, and choice of control groups.…”