Analyzing the electrophysiological effects of local epicardial temperature in experimental studies with isolated hearts.
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.
Bioengineering, Electronics and Telemedicine Group, Polytechnic University of Valencia, Camino de Vera 14, 46022 Valencia, Spain. atormos@eln.upv.es
Alvaro
A
Tormos
Francisco J
FJ
Chorro
José
J
Millet
Luis
L
Such
Joaquín
J
Cánoves
Luis
L
Mainar
Isabel
I
Trapero
Luis
L
Such-Miquel
Antonio
A
Guill
Antonio
A
Alberola
D000818:Animals; D001831:Body Temperature; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D010496:Pericardium / Q000502:physiology*; D011817:Rabbits; D012032:Refractory Period, Electrophysiological; D014693:Ventricular Fibrillation / Q000209:etiology