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This Article Full Text Full Text (PDF) All Versions of this Article: 297/2/H743    most recent 00193.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Chicos, A. B. Articles by Goldberger, J. J. PubMed PubMed Citation Articles by Chicos, A. B. Articles by Goldberger, J. J.

Parasympathetic effects on cardiac electrophysiology during exercise and recovery in patients with left ventricular dysfunction

Bluhm Cardiovascular Center and the Division of Cardiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois

Submitted 27 February 2009 ; accepted in final form 9 June 2009

Depressed parasympathetic activity has been proposed to be associated with an increased risk of sudden death. Parasympathetic effects (PE) on cardiac electrophysiology during exercise and recovery have not been studied in patients with left ventricular dysfunction. We performed noninvasive electrophysiological studies (NI-EPS) and characterized the electrophysiological properties of the sinus node, atrioventricular (AV) node, and ventricle in subjects with depressed left ventricular ejection fraction and dual-chamber defibrillators. NI-EPS were performed during rest, exercise, and recovery at baseline and after parasympathetic blockade with atropine to assess PE (the difference between parameter values in the 2 conditions). Ten subjects (9 men: age, 60 ± 9 yr; and left ventricular ejection fraction, 29 ± 8%) completed the study. All NI-EPS parameters decreased during exercise and trended toward rest values during recovery. PE at rest, during exercise, and during recovery, respectively, were on sinus cycle length, 320 ± 71 (P = 0.0001), 105 ± 60 (P = 0.0003), and 155 ± 82 ms (P = 0.0002); on AV block cycle length, 137 ± 136 (P = 0.09), 37 ± 19 (P = 0.002), and 61 ± 39 ms (P = 0.006); on AV interval, 58 ± 32 (P = 0.035), 22 ± 13 (P = 0.002), and 36 ± 20 ms (P = 0.001); on ventricular effective refractory period, 15.8 ± 11.3 (P = 0.02), 4.7 ± 15.2 (P = 0.38), and 6.8 ± 15.5 ms (P = 0.20); and on QT interval, 13 ± 12 (P = 0.13), 3 ± 17 (P = 0.6), and 20 ± 23 (P = 0.04). In conclusion, we describe for the first time the changes in cardiac electrophysiology and PE during rest, exercise, and recovery in subjects with left ventricular dysfunction. PEs are preserved in these patients. Thus the role of autonomic changes in the pathophysiology of sudden death requires further exploration.

heart failure; nervous system; autonomic