Autonomic nerve activity and the short term variability of Tpeak–Tend interval in dogs with pacing-induced heart failure

Piccirillo, Gianfranco, Magri, Damiano, Pappada', Maria, Maruotti, Antonello, Ogawa, Mashiro, Han, Seongwook, Joung, Boyoung, Rossi, Pietro, Nguyen, Bich Lien, Lin, Shien-Fong and Chen, Peng-Sheng (2012) Autonomic nerve activity and the short term variability of Tpeak–Tend interval in dogs with pacing-induced heart failure. Heart Rhythm.

Abstract

Background
In congestive heart failure (CHF), autonomic nervous system (ANS) activity is known to modulate arrhythmic risk through its effects on myocardial repolarization. An increased interval between the peak and the end of T wave (Tpeak–Tend) has been reported to increase the incidence of sudden cardiac death. However, the ANS influence on Tpeak–Tend interval remains unclear. We directly measured ANS nerve activity in ambulatory dogs with pacing-induced CHF to test the hypothesis that ANS activity modulates the Tpeak–Tend variability index (Tpeak-endVI), the short period variability of Tpeak–Tend interval obtained on 30 beats (Tpeak-endSTV30) and on 5 minute ECG recording (Tpeak-endSTVT).

Methods and results
Using data previously recorded in 6 ambulatory dogs before and after pacing-induced CHF, we assessed ANS activity recorded from an implanted radiotransmitter that monitored integrated left stellate-ganglion nervous activity (iSGNA), integrate vagus nerve activity (iVNA), and electrocardiogram (ECG). We selected for analysis 36 segments recorded at baseline and 36 after induced CHF with similar iSGNA. During CHF, Tpeak-end STV30 (p<0.001) and Tpeak-end STVT (p<0.05) were significantly higher than those at baseline. The multiple linear mixed regression analysis disclosed a significant positive correlation between iSGNA and Tpeak-endSTVT (baseline: ?: 2.92, p<0.001; CHF: ?: 1.13, p<0.001) and a significant negative correlation between iVNA and Tpeak-endSTVT (baseline: ?: -6.74, p<0.001; CHF: ?:-1.42, p<0.001).

Conclusions
In a canine model of pacing-induced CHF, iSGNA correlates positively while iVNA correlates negatively with the Tpeak-endSTVT. These findings suggest that SGNA increases while VNA decreases the dispersion of ventricular repolarization in ambulatory dogs with CHF.

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