McGill Case 299

This case report is kindly provided by Michael Rosengarten from McGill and is part of the McGill Cases. These cases come from the McGill EKG World Encyclopedia. Previous Case: McGill Case 298 | Next Case: McGill Case 300

The ventricular rate of the patient is about 72 beats/minute and it would appear that there is a p wave in front of each QRS complex. The "pr" interval is a little short at about 120 ms. The pacer should have started to pace he atrium when set at 100/min. The failure to do so suggests that the pacing system is non-functional (depleted pacemaker battery, broken lead etc.) or that the pacer is sensing an atrial rhythm faster than 100/min. In this case the pacer is sensing an SVT with an atrial rate of about 150/min. which explains the lack of pacing when the pacer is set to 100/min. The treating physician decided to leave the patient in this rhythm. It is interesting to note that some SVTs and atrial fibrillation can "cure" a sick sinus patient of their bradycardia and the need for a pacemaker. In those cases though that convert to atrial fibrillation anticoagulants are usually considered.