Effects of acute reduction of temperature on ventricular fibrillation activation patterns.
Because of its electrophysiological effects, hypothermia can influence the mechanisms that intervene in the sustaining of ventricular fibrillation. We hypothesized that a rapid and profound reduction of myocardial temperature impedes the maintenance of ventricular fibrillation, leading to termination of the arrhythmia. High-resolution epicardial mapping (series 1; n = 11) and transmural recordings of ventricular activation (series 2; n = 10) were used to analyze ventricular fibrillation modification during rapid myocardial cooling in Langendorff-perfused rabbit hearts. Myocardial cooling was produced by the injection of cold Tyrode into the left ventricle after induction of ventricular fibrillation. Temperature and ventricular fibrillation dominant frequency decay fit an exponential model to arrhythmia termination in all experiments, and both parameters were significantly correlated (r = 0.70, P < 0.0001). Termination of the arrhythmia occurred preferentially in the left ventricle and was associated with a reduction in conduction velocity (-60% in left ventricle and -54% in right ventricle; P < 0.0001) and with activation maps predominantly exhibiting a single wave front, with evidence of wave front extinction. We conclude that a rapid reduction of temperature to <20 degrees C terminates ventricular fibrillation after producing an important depression in myocardial conduction.
Chorro
Francisco J
FJ
Service of Cardiology, Valencia University Clinic Hospital, Spain. Francisco.J.Chorro@uv.es
Guerrero
Juan
J
Ferrero
Angel
A
Tormos
Alvaro
A
Mainar
Luis
L
Millet
Jose
J
Canoves
Joaquin
J
Porres
Juan C
JC
Sanchis
Juan
J
Lopez-Merino
Vicente
V
Such
Luis
L
D000818:Animals; D018780:Body Surface Potential Mapping; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology*; D007036:Hypothermia, Induced; D066298:In Vitro Techniques; D007552:Isotonic Solutions; D011817:Rabbits; D013696:Temperature; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000503:physiopathology*
D007552:Isotonic Solutions; C037692:Tyrode's solution