Abstract 15111: The Combination of Vagal Nerve Stimulation and Intra-Aortic Balloon Pumping Rapidly Modulates Heart Rate and Cardiac Load While Maintaining Hemodynamics in a Dog Model of Acute Heart Failure

Background: In acute heart failure (AHF) condition, excessive tachycardia increases myocardial oxygen consumption (MVO ₂ ). Recently, we have developed an intravenous vagal nerve stimulation (iVNS) catheter which can stimulate right vagal nerve and induce HR reduction (Fig. 1). Since inappropriate bradycardia in AHF condition leads to hemodynamic instability, the use of intra-aortic balloon pumping (IABP) may serve as a beneficial adjunctive therapy for iVNS.

Methods: We induced AHF by the direct ethanol injection (0.5-2 ml/kg) to myocardium. The specialized basket catheter was inserted through the right femoral vein and placed in the superior vena cava. The IABP with 20-cc balloon was inserted through left femoral artery. We also calculated MVO ₂ by the product of coronary flow and the difference of oxygen saturation between coronary artery and coronary sinus. We compared HR, MVO ₂ , and hemodynamics between baseline and 3-min after iVNS (n=11). In addition, we examined the impact of IABP on hemodynamics during iVNS in AHF condition (n=8).

Results: The direct ethanol injection increased LAP (+3.6±7.2 mmHg) and decreased left ventricular ejection fraction (-28±9.8%). The iVNS (20Hz, 10-22 V) rapidly reduced HR (-13±6.9%, P<0.01) and MVO2 (-11±8.1%, P<0.05), while slightly decreased CO (-10±7.3%) and increased LAP (+2.0±3.5 mmHg) (Fig. 2). An adding of IABP during iVNS increased CO (1.2±0.24 vs. 1.3±0.30 l/min, P<0.05) and decreased LAP (14±8.6 vs. 13±8.2 mmHg, P<0.05) .

Conclusion: The combination of iVNS and IABP shows clinical potential as a novel therapy for effectively modulating excessive cardiac load in cases of unstable hemodynamics.