Antiarrhythmic effects of vagal nerve stimulation after cardiac sympathetic denervation in the setting of chronic myocardial infarction

Vagal nerve stimulation (VNS) has been shown to have antiarrhythmic effects, but many of these benefits were demonstrated in the setting of vagal nerve decentralization. The purpose of this study was to evaluate the role of afferent fiber activation during VNS on efferent control of cardiac hemodynamic and electrophysiological parameters. In 37 pigs a 56-electrode sock was placed over the ventricles to record local activation recovery intervals (ARIs), a surrogate of action potential duration. In 12 of 37 animals atropine was given systemically. Right and left VNS were performed under six conditions: both vagal trunks intact ( n = 25), ipsilateral right ( n = 11), ipsilateral left ( n = 14), contralateral right ( n = 7), contralateral left ( n = 10), and bilateral ( n = 25) vagal nerve transection (VNTx). Unilateral VNTx significantly affected heart rate, PR interval, Tau, and global ARIs. Right VNS after ipsilateral VNTx had augmented effects on hemodynamic parameters and increase in ARI, while subsequent bilateral VNTx did not significantly modify this effect (%change in ARI in intact condition 2.2 ± 0.9% vs. ipsilateral VNTx 5.3 ± 1.7% and bilateral VNTx 5.3 ± 0.8%, P < 0.05). Left VNS after left VNTx tended to increase its effects on hemodynamics and ARI response ( P = 0.07), but only after bilateral VNTx did these changes reach significance (intact 1.1 ± 0.5% vs. ipsilateral VNTx 3.6 ± 0.7% and bilateral VNTx 6.6 ± 1.6%, P < 0.05 vs. intact). Contralateral VNTx did not modify VNS response. The effect of atropine on ventricular ARI was similar to bilateral VNTx. We found that VNS activates afferent fibers in the ipsilateral vagal nerve, which reflexively inhibit cardiac parasympathetic efferent electrophysiological and hemodynamic effects.

Download Full-text

Abstract 13813: Intravascular Vagal Nerve Stimulation in Acute Myocardial Infarction Markedly Reduced Infarct Size and Improved Cardiac Function in the Long Term

Circulation ◽

10.1161/circ.132.suppl_3.13813 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Takahiro Arimura ◽

Keita Saku ◽

Takamori Kakino ◽

Takuya Nishikawa ◽

Takeshi Tohyama ◽

...

Keyword(s):

Myocardial Infarction ◽

Heart Failure ◽

Acute Myocardial Infarction ◽

Infarct Size ◽

Nerve Stimulation ◽

Myocardial Damage ◽

Vagal Nerve ◽

Vagal Nerve Stimulation ◽

Lv Function

Backgrounds: In acute myocardial infarction (AMI), the extent of myocardial damage governs the progression to heart failure in the long-term. Therefore, reducing the myocardial damage is prerequisite to prevent chronic heart failure. Although vagal nerve stimulation (VNS) has been repeatedly demonstrated to have the powerful anti-infarct effect, technical difficulties preclude its clinical applications. Recently we developed an new percutaneous, intravascular VNS (iVNS). In this study, we investigated whether iVNS reduces the infarct size and prevents heart failure one month after ischemia reperfusion (IR). Methods: In mongrel dogs, we ligated the left anterior descending coronary artery for 3 hours and reperfused. We transvascularly stimulated the right vagal nerve with a pacing catheter in the superior vena cava. We maximized the intensity of iVNS that did not deteriorate hemodynamics (amplitude; 5.1±2.1 V, pulse width; 0.2ms, frequency; 10 Hz). We started iVNS at the onset of ischemia (iVNS0, n=7) or 90 min after the onset of ischemia (iVNS90, n=7) and continued to 60 min after reperfusion. One month after IR, we compared the infarct size, left ventricular (LV) function and hormonal responses among 3 groups including the no treatment group (IR, n=10). Results: Both iVNS0 and iVNS90 significantly reduced the infarct size (IR: 11.6±3.1, iVNS0: 2.4±2.1, iVNS90: 4.5±1.9%, p<0.05, Figure), improved LV ejection fraction (IR: 50±7, iVNS0: 61±6, iVNS90: 60±5.1%, p<0.05) and decreased LV end-diastolic pressure (IR: 14.6±1.9, iVNS0: 4.2±1.0, iVNS90: 5.0±2.8mmHg, P<0.05). The benefits were larger in iVNS0 than iVNS90. Conclusion: Short term iVNS delivered prior to coronary reperfusion markedly reduced the infarct size and preserved LV function one month after ischemia. Since we can transvascularly deliver iVNS, it may serve as a new non-pharmacological therapeutic strategy and contribute to improve the long term survival in patients with AMI.

Download Full-text