Diminished parasympathetic tone is associated with increased mortality. The risk of sudden death is increased during exercise. Exercise is also associated with diminished parasympathetic tone, raising the question whether parasympathetic tone may provide a natural anti-arrhythmic effect. Thus, the aim of the proposed studies is to address the question: What is the role of parasympathetic tone in modulating cardiac electrophysiology during exercise and recovery? Specific hypotheses are: a) recovery of heart rate and ventricular repolarization after exercise is mediated by sympathetic withdrawal, parasympathetic activation, and sympathetic-parasympathetic interactions -- this will be assessed by sequential autonomic blockade during serial bicycle exercise tests; b) there is diminished parasympathetic effect on recovery of heart rate and QT interval in subjects with coronary artery disease and left ventricular dysfunction -- this will be assessed by serial exercise tests with and without parasympathetic blockade; c) a new index of heart rate variability during recovery correlates with parasympathetic effects on recovery of heart rate and QT interval; d) parasympathetic effects on cardiac electrophysiology persist during exercise and are depressed in subjects with decreased versus normal left ventricular function -- this will be assessed by noninvasive programmed stimulation via implanted devices during sedal exercise testing with and without parasympathetic blockade; e) parasympathetic effects on the QT interval during exercise and recovery correlate with parasympathetic effects on ventricular refractoriness. Validation of these hypotheses will show: 1) parasympathetic tone modulates ventricular repolarization and refractoriness during exercise and recovery; 2) this modulation is suppressed in subjects with left ventricular dysfunction. Understanding the role of parasympathetic tone in modulating cardiac electrophysiology during exercise and recovery will open up a new avenue of research relating autonomic tone and sudden death. If parasympathetic tone does provide an antiarrhythmic effect during exercise and recovery, one could consider developing vagal nerve stimulation during exercise and recovery as a new treatment modality to prevent sudden death.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL070179-02
Application #
6783406
Study Section
Special Emphasis Panel (ZRG1-CCVS (01))
Program Officer
Lathrop, David A
Project Start
2003-08-01
Project End
2007-07-31
Budget Start
2004-08-01
Budget End
2005-07-31
Support Year
2
Fiscal Year
2004
Total Cost
$291,423
Indirect Cost
Name
Northwestern University at Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
Goldberger, Jeffrey J; Johnson, Nils P; Subacius, Haris et al. (2014) Comparison of the physiologic and prognostic implications of the heart rate versus the RR interval. Heart Rhythm 11:1925-33
Banthia, Smriti; Bergner, Daniel W; Chicos, Alexandru B et al. (2013) Detection of cardiovascular autonomic neuropathy using exercise testing in patients with type 2 diabetes mellitus. J Diabetes Complications 27:64-9
Lahiri, Marc K; Chicos, Alexandru; Bergner, Dan et al. (2012) Recovery of heart rate variability and ventricular repolarization indices following exercise. Ann Noninvasive Electrocardiol 17:349-60
Pelchovitz, Daniel J; Ng, Jason; Chicos, Alexandru B et al. (2012) QT-RR hysteresis is caused by differential autonomic states during exercise and recovery. Am J Physiol Heart Circ Physiol 302:H2567-73
Johnson, Nils P; Goldberger, Jeffrey J (2012) Prognostic value of late heart rate recovery after treadmill exercise. Am J Cardiol 110:45-9
Wang, Norman C; Chicos, Alexandru; Banthia, Smriti et al. (2011) Persistent sympathoexcitation long after submaximal exercise in subjects with and without coronary artery disease. Am J Physiol Heart Circ Physiol 301:H912-20
Laing, Susan T; Gluckman, Ty J; Weinberg, Kenneth M et al. (2011) Autonomic effects of exercise-based cardiac rehabilitation. J Cardiopulm Rehabil Prev 31:87-91
Johnson, Nils P; Holly, Thomas A; Goldberger, Jeffrey J (2010) QT dynamics early after exercise as a predictor of mortality. Heart Rhythm 7:1077-84
Ng, Jason; Sundaram, Sri; Kadish, Alan H et al. (2009) Autonomic effects on the spectral analysis of heart rate variability after exercise. Am J Physiol Heart Circ Physiol 297:H1421-8
Chicos, Alexandru B; Kannankeril, Prince J; Kadish, Alan H et al. (2009) Parasympathetic effects on cardiac electrophysiology during exercise and recovery in patients with left ventricular dysfunction. Am J Physiol Heart Circ Physiol 297:H743-9

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