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Diltiazem does not increase ventricular fibrillation threshold during hypothermia
Author(s) -
Bjørnstad H.,
Jenssen D.,
Mortensen E.
Publication year - 1995
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1995.tb04144.x
Subject(s) - medicine , diltiazem , ventricular fibrillation , hypothermia , cardiology , anesthesia , atrial fibrillation , fibrillation , calcium
This study was designed to investigate whether the calcium channel blocker diltiazem affects the threshold for ventricular fibrillation during hypothermia in dogs. Ten dogs were cooled from 37 to 25°C and rewarmed to 37°C. The threshold for ventricular fibrillation was determined at body temperatures 37, 34, 31, 28 and 25°C by programmed electrical stimulation using a stimulation protocol which involved application of maximal five extrastimuli. At 25°C, six dogs were given an i.v. bolus dose of 100 μg‐kg ‐1 followed by a continuous infusion of 100 μg‐kg ‐1 ‐h ‐1 of diltiazem hydrochloride. The other four dogs, were given no drugs at 25°C and served as a control group. The dogs were rewarmed, and the stimulus protocol was performed at the same temperatures as during cooling. Cooling from 37 to 25°C reduced the treshold for ventricular fibrillation in both groups. Heart rate were reduced, monophasic action potential duration at the apex and base of the heart increased from 167±5 ms to 469±17 ms and from 164±5 ms to 466±1 7 ms, respectively, when the temperature was reduced. The ventricular effective refractory period increased from 176±9 ms at 37°C to 472±15 ms at 25°C. Cooling increased QRS time on the ECG from 55±4 ms to 138±13 ms. Addition of diltiazem at 25°C did not affect the threshold for ventricular fibrillation during rewarming. Further, diltiazem at 25°C did not affect the heart rate or refractoriness. Cooling reduces the threshold for ventricular fibrillation. During hypothermia, the calcium channel blocker diltiazem does not seem to affect the threshold for ventricular fibrillation.