[An analysis of the variability in the heart rate in relation to the presence of transient ischemia and to its physiopathological mechanism].
To assess the differences in the pathogenesis of cardiac ischemic events and the role of the autonomic nervous system, we studied the electrocardiographic measures of tonic vagal activity during 24-hour Holter monitoring. We tested the circadian rhythm of the power in the high frequency energy (HF: 0.15-0.40 Hz) of the normal R-R interval power spectrum, the daily percent of successive normal R-R greater than 50 ms (pNN50) and the roots mean square of successive difference of normal R-R intervals (MMSD) in patients with coronary artery disease of comparable angiographic severity. Group A consisted of 5 patients (mean age 62 +/- 8) with chronic stable angina and Group B of 5 patients (mean age 61 +/- 8) with variant angina. Characteristic anginal pattern, typical ST changes during ischemic events on Holter monitoring and angiographic evidence of vasoconstriction induced by hyperventilation distinguished the 2 groups. Mean Cosinor analysis showed the presence of a significant circadian rhythm of HF only in Group A with a peak in the early morning hours (phi at 03.45, % rhythm 50.0, p less than 0.03); a significant reduction of parasympathetic activation was also found in Group B (MSSD: 27.8 vs 15.4, p less than 0.05; pNN50: 2.9 vs 0.6, p less than 0.05). These results suggest a different pattern in circadian variation of HF and lower degree of time and frequency domain of heart rate variability, as a marker of vagal tone in patients with high susceptibility to coronary vasospasm.
Meloni
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C
Divisione di Cardiologia, Istituto Scientifico HS Raffaele, Milano.
Carandente
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O
Bonetti
F
F
Ferrario
F
F
Carandente
F
F
Chierchia
S L
SL
D000788:Angina Pectoris, Variant / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D006328:Cardiac Catheterization; D002908:Chronic Disease; D002932:Cineangiography; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D008297:Male; D008875:Middle Aged
Analisi della variabilità della frequenza cardiaca in relazione alla presenza di ischemia transitoria e al suo meccanismo fisiopatologico.