IMPACTS OF SYSTEMIC HYPERTENSION AND LEFT VENTRICULAR HYPERTROPHY ON OUTCOME OF CARDIOPULMONARY RESUSCITATION AND THERAPEUTIC HYPOTHERMIA IN A CARDIAC ARREST MODEL OF RAT.

BACKGROUND: Systemic hypertension and left ventricular hypertrophy (LVH) are major risk factors of cardiac arrest. However, the impacts of hypertension and LVH on the outcome of cardiopulmonary resuscitation (CPR) and post-resuscitation hypothermia are still undetermined.

METHODS: After 4 min of untreated ventricular fibrillation (VF) and 4 min of CPR, defibrillation was attempted in 16 male spontaneously hypertensive rats (SHR) with LVH and 16 male normotensive Wistar Kyoto (WKY) rats. When restoration of spontaneous circulation (ROSC) was achieved, animals were randomized into either hypothermia or normothermia. For animals subjected to hypothermia, rapid cooling was started immediately after ROSC and a temperature of 33.0 ± 0.4°C was maintained for 2 h. Normothermic animals were maintained at 37.0 ± 0.4°C.

RESULTS: Baseline mean arterial pressure, heart rate, and left ventricle mass were significantly higher but ejection fraction was lower for hypertensive animals. Coronary perfusion pressure was higher for SHR, but no differences in duration of CPR and number of defibrillations required for resuscitation compared with WKY. All of the animals were successfully resuscitated but post-resuscitation cardiac function was severely impaired in hypertensive animals. Serum levels of cardiac troponin T, amino-terminal pro-brain natriuretic peptide, and S100B measured after ROSC were also markedly higher in SHR groups. Fourteen WKY rats (87.5%) survived, whereas only 1 SHR (6.3%, P < 0.001) survived to 96 h.

CONCLUSIONS: In this rat model, systemic hypertension and LVH did not affect ROSC. However, survival was dismal due to elevated severity of cardiac and cerebral injury in hypertensive animals regardless of short-duration hypothermia.