A controlled study of the effects of mental relaxation on autonomic excitatory responses in healthy subjects.
OBJECTIVE
Circumstantial evidence indicates that, in the presence of a suitable substratum, sudden, behaviorally induced increases in sympathetic drive to the cardiovascular system might play an important physiopathological role in various conditions, ranging from arterial hypertension to sudden coronary death. Accordingly, it might be useful to study the effects of behavioral interventions, such as mental relaxation, that might be capable of blunting excitatory autonomic responses. It would also be preferable to study healthy subjects in whom autonomic control is not modified by the presence of disease, and to use noninvasive approaches to minimize the possible emotional impact produced by invasive recordings.


METHODS
We examined healthy subjects who were either subjected to relaxation training (N = 13) or sham relaxation (N = 12). An additional group, treated with beta-adrenergic blockade (N = 12), was also examined. Spectral and cross-spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided quantitative markers of sympathovagal balance modulating the sinoatrial (SA) node, of sympathetic vasomotor modulation, and of the gain of the arterial pressure/heart period baroreflex (index alpha). Subjects were studied at rest, during standing, and during mental arithmetic.


RESULTS
Data indicate that both beta-adrenergic blockade and relaxation training significantly blunted the excitatory autonomic responses to standing and to mental arithmetic. Indices of sympathetic modulation also seemed reduced by beta blockade at rest. No changes were observed with sham training.


CONCLUSIONS
Frequency domain analysis of cardiovascular variabilities, using a totally noninvasive approach, indicates that relaxation training significantly blunts the excitatory autonomic changes produced by standardized behavioral laboratory stimuli.
Lucini
D
D
Centro Ricerca Neurovegetativa, Ospedale L. Sacco, Università di Milano, Italy.
Covacci
G
G
Milani
R
R
Mela
G S
GS
Malliani
A
A
Pagani
M
M
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D000704:Analysis of Variance; D001262:Atenolol / Q000494:pharmacology; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D018849:Controlled Clinical Trials as Topic; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D011187:Posture / Q000502:physiology; D012063:Relaxation / Q000502:physiology* / Q000523:psychology; D012064:Relaxation Therapy; D012146:Rest / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D001262:Atenolol