Abstract 12484: Spinal Cord Stimulation Improves Left Ventricular Function and Decreases Myocardial Oxygen Consumption in Porcine Model of Ischemic Heart Failure
Background Prior experimental studies showed that thoracic spinal cord stimulation (SCS) improved left ventricular (LV) ejection fraction (LVEF) in animal model of ischemic cardiomyopathy. While, it is unclear whether increased LV contractile function with thoracic SCS is associated with increased myocardial oxygen consumption that may subsequently lead to further worsening of LV function and heart failure (HF) progression.
Methods We performed acute thoracic SCS in 11 adult pigs with ischemic HF induced by coronary embolization of left circumflex artery followed by rapid ventricular pacing for 4 wks. At 24 hours off -pacing, all animals underwent invasive hemodynamic assessment to determine LV contractile function, myocardial oxygen consumption and blood sampling to measure serum norepinephrine levels before (baseline) and after short-term SCS. SCS was performed twice for 15 minutes with 30 minutes apart (recovery) at T1-T2 level with 50Hz frequency, pulse width 0.2ms, and the same 90% of motor threshold as determined by 2Hz output.
Results Echocardiogram showed significant decreased in LVEF (34.1±1.9% vs. 66.5±1.7%, P<0.01) after induction of HF as compared with before HF. As compared with baseline, 15 mins of acute SCS significantly increased LV contractile function as determined by +dP/dt (Fig 1 P<0.05). Withdrawal of SCS during recovery decreased +dP/dt back to baseline but increased again with SCS (Fig 1 P<0.05). Furthermore, there was a significant decreased in myocardial oxygen consumption after SCS as compared to baseline (Fig 2 P=0.006), but no change in serum norepinephrine level (314±4.7 vs. 313±3.1 pg/ml, P=0.9).
Conclusions In porcine model of ischemic HF, acute SCS Improves LV contractile function and decreases myocardial oxygen consumption without evidence of excessive sympathetic activation as measured serum norepinephrine levels. These findings have important implication on the long-term application of SCS for treatment of ischemic HF.
- © 2011 by American Heart Association, Inc.