Abstract 1779: Post Resuscitation Myocardial Microcirculatory Dysfunction After Prolonged Ventricular Fibrillation
Background: Post resuscitation myocardial stunning with resultant LV systolic and diastolic dysfunction is common after prolonged ventricular fibrillation (VF). The etiology of such global LV dysfunction is thought to be related to ischemia occurring during the no-flow period of untreated VF and the low flow state produced with cardiopulmonary resuscitation, reperfusion injury after restoration of circulation, and possibly electrical injury during defibrillation. The role of the myocardial microcirculation has not been previously investigated in an intact, in-vivo model of post resuscitation myocardial dysfunction.
Methods: Domestic swine (n = 5; 25–30 kg) were electrically fibrillated and left untreated for 12 minutes. Aggressive ACLS was performed to restore spontaneous circulation. Hemodynamics, left ventricular ejection fraction (LVEF), cardiac output, and coronary flow reserve (CFR) [using the standard technique of intracoronary Doppler flow measurements before and after intracoronary administration of 48 mcg adenosine] were performed pre-arrest and post resuscitation at 30 min, 1, and 4 hours. Abnormal CFR was assumed to indicate abnormal myocardial microcirculatory function since these swine had no coronary artery obstructive disease.
Results: Significant differences (p < 0.05) were found between pre and post resuscitation HR, RaP, LVEF, Cardiac Output (l/min), and CFR. Coronary flow reserve decreased by more than 50% in the post resuscitation period indicating substantial microcirculatory dysfunction. This decrease in CFR paralleled the decreases in LV function (i.e. ↓ LVEF, ↑ RaP, and ↓CO).
Conclusion: In this swine model of prolonged VF followed by successful resuscitation, significant declines in left ventricular function were accompanied by marked dysfunction of the myocardial microcirculation. Therapies shown to improve microcirculation abnormalities during ACS and PCI should be considered in the post resuscitation period.