RESEARCH: pure autonomic failure and multiple system atrophy

[Guest guest]

J Neurol 2002 May;249(5):542-8

Haemodynamic responses during head-up tilt and tilt reversal in two groups

with

chronic autonomic failure: pure autonomic failure and multiple system

atrophy.

Chandler MP, Mathias CJ.

Autonomic Unit, National Hospital for Neurology & Neurosurgery, Queen Square

&

University Department of Clinical Neurology, Institute of Neurology,

University

College London, London, UK.

Continuous haemodynamic responses to head-up tilt (HUT) and its reversal

were

studied in 21 subjects with sympathetic denervation due to primary chronic

autonomic failure; 10 had pure autonomic failure (PAF; peripheral failure)

and

11 had multiple system atrophy (MSA; central failure); 8 healthy subjects

(controls) also were studied. Supine systolic, diastolic and mean arterial

pressure (MAP) and total peripheral resistance (TPR) were highest in PAF.

The

MAP response to HUT and tilt reversal were different between groups. After

HUT,

MAP increased in controls (12+/-4 mmHg), but decreased in PAF and MSA

(41+/-4 &

19+/-4 mmHg respectively); the fall in PAF was greater than in MSA. With

tilt

reversal, MAP returned promptly, but not entirely to pretilt levels in

controls,

with small (insignificant) overshoots in MSA and PAF. The TPR response to

HUT

and tilt reversal was different between groups. After HUT, TPR increased in

controls (0.31+/-0.04 PRU), decreased in PAF (0.23+/-0.1 PRU) and was

unchanged

in MSA. With tilt reversal, TPR remained elevated (15 %) above baseline in

the

controls and rose in PAF (13 %) with no change in MSA. There were no

differences

in supine heart rate (HR), stroke volume (SV) or cardiac output (CO) between

the

three groups; HR, SV or CO responses to HUT or tilt reversal also did not

differ

between the groups.Thus, after HUT, MAP decreased, with greater hypotension

induced in PAF than MSA. Since CO did not differ between groups, the

decrease in

TPR appears to account for the greater fall in BP in PAF than in MSA. The

elevated TPR at rest pre-tilt and after tilt reversal probably contributed

to

supine hypertension in PAF. These haemodynamic observations may aid

therapeutic

strategies to reduce orthostatic hypotension and prevent supine

hypertension.

PMID: 12021943 [PubMed - in process]