Desflurane Inhibits U Wave in Electrocardiogram

Background: Volatile anesthetics inhibit cardiac transmembrane ionic currents and intracellular ionic activity and exert antiarrhythmic actions. Among electrocardiogram (ECG) waveforms, the effect of volatile anesthetics on U wave has never been studied. The aim of the present observational study was to evaluate the possible effect of desflurane on U wave in anesthetized patients. Methods: Peri-operative ECG tracings (lead II) were recorded and analyzed from 24 gynecologic patients (American Society of Anesthesiologists (ASA), class 1). Anesthesia was routinely induced with thiopental, fentanyl and succinylcholine and maintained with desflurane (1 to 1.5 minimal alveolar concentration (MAC)) and O2. U wave amplitude (Uamp) was manually measured from amplified ECG records. Results: Discernible U wave in 24 patients varied in amplitude (64 24 V). U wave was three times larger when heart rate increased to maximum during tracheal intubation. Similarly, Uamp was augmented (285% 58% of the control) in extrasystolic beats elicited by tracheal intubation. Desflurane (1 to 1.5 MAC) significantly and reversibly suppressed Uamp (a decrease by 60 24 V, n = 24, p < 0.05). Conclusions: The suppressive effect of desflurane on Uamp might be explained by its inhibitory effects on transmembrane ionic currents, intracellular calcium load and delayed afterdepolarizations. Our results support a contributory role of afterpotentials in the genesis of U wave.