Abnormal autonomic control of the cardiovascular system in syndrome X.
Anomalies of autonomic control of the coronary circulation may play a role in the development of syndrome X (angina pectoris, ischemic-appearing results on exercise test, and normal coronary arteriograms). Twenty-six patients with syndrome X and 20 healthy sex- and age-matched control subjects were studied by means of analysis of heart rate variability during 24-hour Holter monitoring. Spectral and nonspectral parameters of heart rate variability were investigated. Mean heart rate was similar in patients with syndrome X and in control subjects. Patients with syndrome X had significantly lower standard deviation of all normal RR intervals, a lower percentage of adjacent normal RR intervals > 50 ms in difference (126.4 +/- 22 vs 149 +/- 43 ms, p < 0.05; 6.3 +/- 4 vs 11.2 +/- 7%, p < 0.05; respectively), and a trend toward lower values of time-domain parameters. Lower values of total power and low frequency were also observed in patients with syndrome X (1273 +/- 693 vs 1790 +/- 989 ms2, p < 0.05; 406 +/- 176 vs 729 +/- 455 ms2, p < 0.01, respectively). An inverse correlation between heart rate and measures of heart rate variability was found in syndrome X but not in control subjects. High- and low-frequency power showed a similar circadian pattern in syndrome X patients and control subjects. Patients and control subjects were then allocated into 2 groups according to the median RR duration: syndrome X1 and control 1 with high mean heart rate, and syndrome X2 and control 2 with low mean heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Rosano
G M
GM
National Heart & Lung Institute, Royal Brompton National Heart & Lung Hospital, London, United Kingdom.
Ponikowski
P
P
Adamopoulos
S
S
Collins
P
P
Poole-Wilson
P A
PA
Coats
A J
AJ
Kaski
J C
JC
D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D016022:Case-Control Studies; D002940:Circadian Rhythm; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D005583:Fourier Analysis; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000503:physiopathology*; D008875:Middle Aged; D015588:Observer Variation; D012815:Signal Processing, Computer-Assisted