title: Effects of acid-base imbalance on myocardial pacing thresholds.
abstract: The effects of acid-base imbalance on ventricular pacing thresholds were studied in anesthetized dogs with complete heart block with the use of an oscilloscope and current probe. Acidosis (base excess-15) and alkalosis (base excess + 15)both resulted in significant increases in threshold voltage and current requirements at all stimulus durations tested. Chronaxie, however, was not significantly affected by shifts in acid-base balance. Abnormalities of acid-base status may adversely affect the accuracy of threshold values obtained during evaluation of different electrode designs and during electrodes implantation for clinical cardiac pacing.
mesh_terms: D000138:Acidosis / Q000503:physiopathology*; D000471:Alkalosis / Q000503:physiopathology*; D000818:Animals; D001639:Bicarbonates; D004285:Dogs; D006327:Heart Block / Q000503:physiopathology / Q000628:therapy*; D006329:Heart Conduction System / Q000503:physiopathology*; D006851:Hydrochloric Acid; D010138:Pacemaker, Artificial
chemical_list: D001639:Bicarbonates; D006851:Hydrochloric Acid