Key result
Regional hypo- and hyperthermia exerted reversible and opposite effects upon myocardial refractoriness and conduction velocity, without significantly modifying ventricular activation wavelength.
Why the study?
Do local epicardial temperature changes affect myocardial refractoriness, conduction velocity, and ventricular fibrillation activation frequency in isolated rabbit hearts?
Do local epicardial temperature changes affect myocardial refractoriness, conduction velocity, and ventricular fibrillation activation frequency in isolated rabbit hearts?
Local epicardial temperature changes exert reversible and opposite effects on myocardial refractoriness and conduction velocity in isolated rabbit hearts.
Local epicardial temperature changes should not alter clinical practice; hypothesis-generating for arrhythmia mechanisms in translational models.
As a result of their modulating effects upon myocardial electrophysiology, both hypo- and hyperthermia can be used to study the mechanisms that generate or sustain cardiac arrhythmias. The present study describes an original electrode developed with thick-film technology and capable of controlling regional temperature variations in the epicardium while simultaneously registering its electrical activity. In this way, it is possible to measure electrophysiological parameters of the heart at different temperatures. The results obtained with this device in a study with isolated and perfused rabbit hearts are reported. An exploration has been made of the effects of local temperature changes upon the electrophysiological parameters implicated in myocardial conduction. Likewise, an analysis has been made of the influence of local temperature upon ventricular fibrillation activation frequency. It is concluded that both regional hypo- and hyperthermia exert reversible and opposite effects upon myocardial refractoriness and conduction velocity in the altered zone. The ventricular activation wavelength determined during constant pacing at 250 ms cycles is not significantly modified, however. During ventricular fibrillation, the changes in the fibrillatory frequency do not seem to be transmitted to normal temperature zones.
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Tormos et al. (2008) studied Cardiac arrhythmias. Local epicardial temperature changes (hypo- and hyperthermia) vs. Normal temperature zones was evaluated on Electrophysiological parameters implicated in myocardial conduction and ventricular fibrillation activation frequency. Regional hypo- and hyperthermia exerted reversible and opposite effects upon myocardial refractoriness and conduction velocity, without significantly modifying ventricular activation wavelength.
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