Abstract 16027: The Induction of Mild Hypothermia Improves Oxygen Supply-Demand Balance in a Model of Acute Ischemic Heart Failure in Pigs.
Background: The induction of mild hypothermia (MH, 32–34 °C) is guideline therapy after cardiac arrest. In normal and resuscitated porcine hearts, MH exerts a positive inotropic effect and reduces whole body oxygen demand.
Hypothesis: The induction of MH is a beneficial intervention in acute ischemic heart failure.
Methods: In a closed chest preparation, 15 anesthetized pigs (70±1 kg) were acutely instrumented with a Swan-Ganz catheter, a left ventricular (LV) pressure-volume catheter, a right atrial pacing probe, an intraaortic balloon catheter and an intravascular cooling device. 45 μm polystyrole microspheres were infused repeatedly into the left circumflex coronary artery (coronary microembolisation, CME) until cardiac power output decreased by >40 %. Pigs were then assigned to either normothermia (NT, 38 °C, n=8) or MH (33 °C, n=7). Data are reported at 6 h after CME (CME 6) vs. control. *: p<0.05 vs. control, #: p<0.05 vs. NT.
Results: The target temperature of 33.0 °C was reached at 193±13 min after CME. Heart rate (bpm) increased during NT (99±6* vs. 86±4), but decreased during MH (65±4*,# vs. 86±4). Cardiac output was reduced to a similar degree in both groups, but mean aortic pressure (AOP) was less decreased in MH due to increased systemic vascular resistance (mmHg/l/min, MH: 20±1*,# vs. 16±1, NT: 14±1 vs. 17±1). Also, LV dP/dtmax was less decreased vs. control in MH (−31±4 %) than in NT (−45±2 %#). Central venous oxygen saturation (%) was markedly higher in MH than in NT due to reduced whole body oxygen consumption during MH (ml/min, MH: 193±8*,# vs. 332±18, NT: 274±13 vs. 311±10).
Conclusions: The induction of MH in acute ischemic heart failure markedly improves systemic oxygen supply-demand balance by reducing systemic oxygen demand and further exerts a slight positive inotropic effect. These data warrant clinical studies of MH as a rescue intervention in acute heart failure and cardiogenic shock.
- © 2010 by American Heart Association, Inc.