Self-Resolving Mobitz Type II Second-Degree Heart Block (Atypical Wenckebach Block) After Cesarean Section Under Subarachnoid Block: A Case Report

The majority of the perioperative arrhythmias in patients undergoing cesarean section under spinal anesthesia are benign. We report a case of a 30-year-old full-term parturient with a history of an uneventful previous cesarean section. She had no preexisting comorbidities. She subsequently underwent another emergency cesarean section three years later due to abdominal pain and scar tenderness indicative of impending rupture. Two hours after an uneventful surgery, the patient developed epigastric pain with a prolonged PR interval (280 ms) and intermittent second-degree AV block with two consecutive blocked P waves, which was consistent with Mobitz type II second-degree heart block (atypical Wenckebach block). However, she remained hemodynamically stable throughout. Serial electrocardiogram (ECG) did not demonstrate any evidence of ST-T wave changes, and normal troponin I and echocardiography excluded myocardial ischemia as a potential cause for the arrhythmia. Normal serum electrolytes and the resolution of the sensorimotor block caused by the spinal anesthesia excluded other known causes for such ECG changes. The PR interval gradually decreased to 240 ms on the second postoperative day and normalized to 200 ms on the fifth postoperative day. Such patients, especially those with a wide QRS complex, are susceptible to developing dangerous ventricular arrhythmias that can adversely affect circulatory function. Close vigil is the key to avoiding adverse perioperative outcomes.