{'fraction_non_alphanumeric': 0.036891679748822605, 'fraction_numerical': 0.02119309262166405, 'mean_word_length': 5.262899262899263, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Additive Cardiac Depression by Volatile Anesthetics in Isolated Hearts After Chronic Amiodarone Treatment

Some patients undergoing general anesthesia may be chronically receiving the antidysrhythmic drug amiodarone.The half-life of this drug is very long and it may not be advisable or possible to discontinue its administration prior to anesthesia. We examined depressant effects of three volatile anesthetics in hearts isolated from guinea pigs chronically treated with amiodarone. Hearts were isolated and perfused retrogradely through the aorta with oxygenated Krebs-Ringer solution at 37 degrees C at constant pressure. Variables measured in 26 hearts were heart rate (HR), atrioventricular, intraatrial, and intraventricualr conduction times (AVCT, IACT, IVCT) during pacing at 240 bpm, coronary flow, and left ventricular pressure (LVP). Amiodarone (20 mg intraperitoneally) or placebo (Group 1) was given once daily for 1 (Group 2) or 4 (Group 3) wk. Cardiac tissue concentrations of amiodarone were similar (12.1 micro gram/g wet weight) in hearts in Groups 2 and 3 but serum levels were twice as high in hearts in Group 3 as in Group 2 (0.33 vs 0.17 micro gram/mL). Before anesthetic exposure, all variables for hearts in Group 2 were not significantly different from those in Group 1. Significantly, for hearts in Group 3, compared to those in Group 1, HR was slower (-14%), conduction times were longer (IACT + 5 ms, IVCT + 4 ms, AVCT + 9 ms), coronary flow was higher (+23%), and LVP was lower (-12%). After control measurements, hearts were exposed to 0.5 and 1 minimum alveolar anesthetic concentration (MAC) halothane, enflurane, and isoflurane in random order. Each anesthetic slowed HR, prolonged IACT and AVCT, and decreased LVP in a dose-dependent manner; only isoflurane increased flow in a dose-dependent manner. Enflurane depressed HR and LVP more than halothane or isoflurane, halothane decreased LVP more than isoflurane, and isoflurane increased coronary flow more than halothane or enflurane. The changes in these variables due to anesthetic effects were statistically additive to the changes due to amiodarone. Our results indicate that all three anesthetics augment cardiac depression due to chronic administration of amiodarone. This study in isolated hearts suggests that patients on chronic amiodarone therapy for dysrhythmias may exhibit pronounced impairment of conduction and contractility, especially with enflurane, and augmented coronary vasodilation, especially with isoflurane. (Anesth Analg 1995;80:917-24)