Thermotolerance does not reduce the size or remodeling of radiofrequency lesions in the rat myocardium

Abstract

Thermotolerance does not reduce the size or remodeling of RF lesions in the rat myocardium.

Arrhythmogenesis after acute myocardial necrosis with and without preceding ischemia in rats

“…The area of coagulation necrosis in our experiments was similar to that reported by Antonio et al [9], displaying macroscopically well-demarcated borders from normal myocardium [10,11]. The size of the necrotic area was comparable to that after non-reperfused MI and was highly reproducible; this observation carries important implications in MI animal models, in which constant infarct size represents a major strength.…”

“…As previously described [9][10][11], a left thoracotomy was performed, the pectoral muscles were dissected and the thoracic cage was opened with a blunt forceps; the heart was exposed, the pericardium was removed and the heart was exteriorized. A suture (7-0 Everpoint, Ethicon, Johnson & Johnson, New Brunswick, NJ, USA) was passed through the apex, allowing a slight caudal-lateral traction of the heart.…”

“…In 2009, Antonio et al [9] described a rat model of direct myocardial necrosis without preceding ischemia, induced by epicardial radiofrequency current application, and the same group recently expanded its description [10,11]. In addition to its utility in heart failure studies, this model presents several advantages in the investigation of MI-related VT/VF, because (a) application of radiofrequency current produces immediate coagulation necrosis of highly reproducible size, without preceding ischemia [9][10][11]; this irreversible loss of cellular excitability is known to occur at temperatures > 50.…”

“…In addition to its utility in heart failure studies, this model presents several advantages in the investigation of MI-related VT/VF, because (a) application of radiofrequency current produces immediate coagulation necrosis of highly reproducible size, without preceding ischemia [9][10][11]; this irreversible loss of cellular excitability is known to occur at temperatures > 50. 0°C and is associated with homogenous electrophysiologic properties [12,13]; (b) previous histological studies have demonstrated the production of a well-demarcated lesion after radiofrequency ablation, with abrupt transition from necrotic to normal myocardium [12].…”

Atrial fibrillation promotion in a rat model of heart failure induced by left ventricle radiofrequency ablation

“…However, this model has drawbacks such as elevated significant immediate mortality and high variability of myocardial infarction size [ [10] , [11] ]. As an alternative to coronary occlusion, we have recently demonstrated a method of inducing myocardial infarction in rats by left ventricle radiofrequency (RF) ablation which is associated with homogenous infarct size and low mortality [ [12] , [13] , [14] ]. In addition, the histopathologic evolution, severity of left ventricular dysfunction and CHF outcome reproduced a myocardial infarction from coronary occlusion [ 12 ].…”