Autonomic Nervous System Activity Measured Directly and QT Interval Variability in Normal and Pacing-Induced Tachycardia Heart Failure Dogs

• Published in: Journal of the American College of Cardiology Vol. 54; no. 9; pp. 840 - 850
• Main Authors: Piccirillo, Gianfranco, MD, PhD, Magrì, Damiano, MD, Ogawa, Masahiro, MD, PhD, Song, Juan, PhD, Chong, Voon J, Han, Seongwook, MD, PhD, Joung, Boyoung, MD, PhD, Choi, Eue-Keun, MD, PhD, Hwang, Samuel, BS, Chen, Lan S., MD, Lin, Shien-Fong, PhD, Chen, Peng-Sheng, MD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25-08-2009; Elsevier Limited
• Subjects: Analysis of Variance; Animals; autonomic nervous system; Autonomic Nervous System - physiology; Autonomic Nervous System - physiopathology; Cardiac arrhythmia; Cardiac Pacing, Artificial; Cardiology; Cardiovascular; congestive heart failure; Disease Models, Animal; Dogs; Electrocardiography; Heart failure; Heart Failure - etiology; Internal Medicine; QT variability index; Regression analysis; Software; Studies; sudden cardiac death; Sympathetic Nervous System - physiology; Sympathetic Nervous System - physiopathology; Tachycardia - complications; Tachycardia - diagnosis; Vagus Nerve - physiology; Vagus Nerve - physiopathology; CHF; Data Sciences International; ANS; QT variance; QT mean; RR mean; sudden cardiac death; RR variance; QT m; congestive heart failure; DSI; integrate vagus nerve activity; iSGNA; QT v; QTc; corrected QT interval; autonomic nervous system; TDR; RR m; QTVI; RR v; iVNA; QT variability index; SCD; transmural dispersion of repolarization; integrated left stellate-ganglion nervous activity; QTm; RRm; QTv; RRv
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/j.jacc.2009.06.008

Objectives This study sought to find out more about the relationship between sympathetic and vagal nerve activity and the cardiac repolarization in a canine model of pacing-induced tachycardia congestive heart failure (CHF). Background The QT variability index (QTVI), a noninvasive marker of temporal cardiac repolarization dispersion, is among the risk factors for sudden death during CHF. Among factors influencing this variable are the myocardial damage and the autonomic nervous system activity typical of dilated cardiomyopathy. Methods We assessed autonomic nervous system activity recorded from an implanted data transmitter that monitored integrated left stellate-ganglion nervous activity, integrated vagus nerve activity, and electrocardiogram. We collected 36 segments recorded at baseline and 36 after induced CHF. We then arbitrarily identified recording segments as containing low or high sympathetic activity values, and we compared corrected QT intervals and the QTVI under a given sympathetic activity condition at baseline and after inducing CHF. Results In the high sympathetic activity subgroup, both QT variables increased from baseline to CHF (corrected QT intervals, p < 0.01; QTVI, p < 0.05) whereas in the low sympathetic activity subgroup they remained unchanged. The baseline QTVI correlated inversely with integrated vagus nerve activity (r2 = 0.16; β = −0.47; p < 0.05) whereas, during CHF, the QTVI correlated directly with integrated left stellate-ganglion nervous activity (r2 = 0.32; β = 0.27, p < 0.01). Conclusions During CHF, sympathetic activation is associated with an increase in the QT interval and QTVI. Because these changes vary over time, they could result from myocardial structural damage and sympathetic activation combined. Conversely, under normal conditions, no relationship exists between sympathetic activation and the QT variables.