Enhanced dispersion of repolarization explains increased arrhythmogenesis in severe versus therapeutic hypothermia.
Circ Arrhythm Electrophysiol
; 4(1): 79-86, 2011 Feb.
Article
en En
| MEDLINE
| ID: mdl-21163888
ABSTRACT
BACKGROUND:
Hypothermia is proarrhythmic, and, as the use of therapeutic hypothermia (TH) increases, it is critically important to understand the electrophysiological effects of hypothermia on cardiac myocytes and arrhythmia substrates. We tested the hypothesis that hypothermia-enhanced transmural dispersion of repolarization (DOR) is a mechanism of arrhythmogenesis in hypothermia. In addition, we investigated whether the degree of hypothermia, the rate of temperature change, and cooling versus rewarming would alter hypothermia-induced arrhythmia substrates. METHODS ANDRESULTS:
Optical action potentials were recorded from cells spanning the transmural wall of canine left ventricular wedge preparations at baseline (36°C), during cooling and during rewarming. Electrophysiological parameters were examined while varying the depth of hypothermia. On cooling to 26°C, DOR increased from 26±4 ms to 93±18 ms (P=0.021); conduction velocity decreased from 35±5 cm/s to 22±5 cm/s (P=0.010). On rewarming to 36°C, DOR remained prolonged, whereas conduction velocity returned to baseline. Conduction block and reentry was observed in all severe hypothermia preparations. Ventricular fibrillation/ventricular tachycardia was seen more during rewarming (4/5) versus cooling (2/6). In TH (n=7), cooling to 32°C mildly increased DOR (31±6 to 50±9, P=0.012), with return to baseline on rewarming and was associated with decreased arrhythmia susceptibility. Increased rate of cooling did not further enhance DOR or arrhythmogenesis.CONCLUSIONS:
Hypothermia amplifies DOR and is a mechanism for arrhythmogenesis. DOR is directly dependent on the depth of cooling and rewarming. This provides insight into the clinical observation of a low incidence of arrhythmias in TH and has implications for protocols for the clinical application of TH.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Arritmias Cardíacas
/
Índice de Severidad de la Enfermedad
/
Sistema de Conducción Cardíaco
/
Hipotermia
/
Hipotermia Inducida
Tipo de estudio:
Etiology_studies
/
Guideline
/
Incidence_studies
/
Prognostic_studies
/
Risk_factors_studies
Límite:
Animals
Idioma:
En
Revista:
Circ Arrhythm Electrophysiol
Asunto de la revista:
ANGIOLOGIA
/
CARDIOLOGIA
Año:
2011
Tipo del documento:
Article
País de afiliación:
Estados Unidos