PMC5804611_01
Preoperative electrocardiogram. The tracing of lead II shows second-degree atrioventricular block with 2:1 AV conduction, ventricular rate of 46 beats per minute. Every other P wave (marked) was regularly conducted. Note the short PR interval during conducted complexes and the narrow QRS complexes
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Fig1
However, routine preoperative resting 12-lead electrocardiogram (ECG) revealed a second-degree 2:1 AV block with a narrow QRS complex (0.102 s), heart rate (HR) of 46 bpm, normal axis, and with no ischemic change (Fig. 1).
Intraoperative monitor electrocardiogram following induction of general anesthesia. The traces show complete atrioventricular block with junctional escape rhythm of approximately 30-40 beats per minute. The P waves (marked) were completely dissociated from the QRS complexes. Artifacts most likely due to poor electrode contact with the skin caused the noisy baseline in this tracing
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Fig2
Conversely, the 2:1 AV block progressively converted to complete AV block (Fig. 2).