Inadvertent Left Ventricle Endocardial or Uncomplicated Right Ventricular Pacing: How to Differentiate in the Emergency Department.

BACKGROUND: Temporary transvenous pacemaker implantation is an important and critical procedure for emergency physicians. Traditionally, temporary pacemakers are inserted by electrocardiography (ECG) guidance in the emergency department because fluoroscopy at the bedside in an unstable patient can be limited by time and equipment availability. However, in the presence of atrial septal defect, ventricular septal defect, and patent foramen ovale, the pacemaker lead can be implanted inadvertently into the left ventricle or directly into the coronary sinus instead of right ventricle. Regular pacemaker rhythm can be achieved despite inadvertent implantation of the pacemaker lead into the left ventricle, leading to ignorance of the possibility of lead malposition. CASE REPORT: A 65-year-old female patient with hemodynamic instability and complete atrioventricular block underwent temporary pacemaker implantation via right jugular vein with ECG guidance at the emergency department. Approximately 12 h after implantation, it was noticed that the ECG revealed right bundle branch block (RBBB)-type paced QRS complexes. Diagnostic workup revealed that the lead was inadvertently located in the left ventricular apex. This case illustrates the importance of careful scrutiny of the 12-lead ECG and imaging clues in identifying lead malposition in the emergency department. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Because inadvertent left ventricle endocardial pacing carries a high risk for systemic embolization, it is important to determine whether an RBBB pattern induced by ventricular pacing is the result of a malpositioned lead or uncomplicated transvenous right ventricular pacing.