A new approach to normalize myocardial temperature in the open-chest pig model

Abstract

To prevent unphysiological temperature fluctuations in the myocardium in the open-chest model, we constructed a thermocage. Five pigs under pentobarbital sodium anesthesia underwent repetitive left anterior descending (LAD) coronary artery occlusions. Myocardial temperature was measured without any thoracic temperature-controlling device and in the presence of either a heating lamp or the thermocage. Without any thoracic temperature-controlling device, the temperature at 5-mm myocardial depth was 1.28 +/- 0.33 degrees C below the intra-abdominal temperature (P < 0.05). During a proximal 5-min LAD occlusion, myocardial temperature decreased by 1.86 +/- 1.02 degrees C in the ischemic area (P < 0.05). Both the heating lamp and the thermocage abolished the difference between intra-abdominal and myocardial temperatures and prevented the decrease in myocardial temperature during ischemia. Only the thermocage minimized myocardial temperature fluctuations due to air currents and prevented epicardial exsiccation. We conclude that either a thermocage or a heating lamp may be used to normalize myocardial temperature in the open-chest pig model. However, the thermocage is superior to the lamp in minimizing temperature fluctuations and preventing epicardial exsiccation.

A minimally invasive method for induction of myocardial infarction in an animal model using tungsten spirals

“…Pericardial incision and development of pneumthorax have important hemodynamic effects [29,30] including changes in intrathoracic pressure compared with a closed chest model [31]. Cooling of the myocardium is necessary during the intervention but is difficult to control and crucially affects the size of the induced infarction [32,33]. Moreover, normal cardiac function is impaired by incision of the chest wall in models of acute myocardial infarction [28], and major surgery always affects the local and global immunological and inflammatory response [34].…”

CaMKII inhibition has dual effects on spontaneous Ca2+ release and Ca2+ alternans in ventricular cardiomyocytes from mice with a gain-of-function RyR2 mutation

“…One can also observe contractile function visually during the experimental protocol. However, this method also leads to the exposure of the heart to room temperature, and creates an unphysiological environment (181). There will also be a higher degree of evaporation from the epicardial surface, and together these factors can lead to excessive cooling of the heart (181).…”

“…However, this method also leads to the exposure of the heart to room temperature, and creates an unphysiological environment (181). There will also be a higher degree of evaporation from the epicardial surface, and together these factors can lead to excessive cooling of the heart (181). As the incidence of arrhythmia can be affected by myocardial temperature, measures were taken to limit evaporation.…”

Transauricular embolization of the rabbit coronary artery for experimental myocardial infarction: comparison of a minimally invasive closed-chest model with open-chest surgery

“…The preceding pericardial incision bears little pathophysiological relevance to human clinical afflictions and may disturb the progression of myocardial remodelling, whereas major surgery alone may affect whole body homeostasis and alter local and systemic immunological and inflammatory responses [6,7]. Alternative closed-chest models of EMI that mainly use endovascular catheterization techniques have been developed, where transcatheter access to the coronaries is typically gained via surgical cutdown and exposure of the carotid or femoral artery.…”