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Early and Late Ischemic Preconditioning
Protect Against Reperfusion-Induced
Arrhythmias Following Reversible
Sustained Ischemia in Conscious Sheep

Lascano, Elena Catalina; del Valle, Héctor Fabián;
Negroni, Jorge Antonio

Department of Physiology, Pharmacology and Biochemistry,
Favaloro University, Buenos Aires, Argentina

Introduction: Reperfusion-induced arrhythmias following irreversible ischemia are not reduced by early preconditioning (EP) in conscious animals, while late preconditioning (LP) results are controversial. However, there are no data regarding the protective action of EP and LP against arrhythmias following a reversible ischemia in conscious animals.

Objective: The purpose of this study was to investigate whether EP and LP protect against reperfusion-induced arrhythmias in conscious sheep submitted to a 12 min ischemic period:

Material and Methods: Adult sheep were instrumented with an intraventricular pressure microtransducer. A week later the experiments were performed in the fully conscious state. An external electrocardiogram and the pressure signal were used to assess arrhythmias. Lidocaine (1-2 mg/kg) was administered if VT lasted more than 30 sec. If VT evolved to VF, one or two cardiovertive shocks (200-300 Joules) were applied. If cardioversion was unsuccessful the animal was sacrificed with an overdose of anesthesia. The animals were divided in 2 groups; Control (C): 12 min ischemia followed by 15 min reperfusion; EP: 6 periods of 5 min ischemia-5 min reperfusion followed by 45 min of normal perfusion were performed before the 12 min ischemia and subsequent 15 min reperfusion; LP: same as EP, except that a 24 hr interval was allowed between the preconditioning periods and the 12 min ischemia.

Results: Sinus rhythm was present during ischemia. Arrhythmia incidence and severity (ASI) at the onset of reperfusion was diagnosed according to the Lambeth convention as shown in the Table 1.

Conclusions: Results show that EP and LP protect against arrhythmia incidence following reversible ischemia in conscious sheep.

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
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Dr. Armando Pacher
Technical Committee - CETIFAC
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