Case #6 — Proarrhythmic Antiarrhythmic

by Mark Pollet, MD, and Mohammad Saeed, MD

A 56-year-old man with a history of atypical atrial flutter related to atrial septal defect repair presented at the emergency department with palpitations and light-headedness. An electrocardiogram (ECG) was performed (Fig. 1). He had undergone an ablation procedure and therapy with metoprolol and flecainide. He had a history of cardiac arrest and had received a Teligen® model E110 dual-chamber implantable cardioverter-defibrillator (ICD) (Boston Scientific Corporation; Natick, Mass). The ICD was programmed in DDD mode, with a lower rate limit of 60 beats/min and an upper limit of 120 beats/min. Ventricular tachycardia therapy was set to begin at 210 beats/min, and ventricular fibrillation therapy at >230 beats/min.

Case #5 — To Pace or Not to Pace?

by Nadeen N. Faza, MD, Kainat Khalid, MD, Mohammad Saeed, MD, and Yochai Birnbaum, MD, FACC

A 75-year-old man with a medical history of sick sinus syndrome and left bundle branch block presented for evaluation of chest pain. The patient had a dual-chamber permanent pacemaker. Figure 1 shows his electrocardiogram (ECG).

Case #4 — An Unusual Presentation of QT Prolongation

by Mohammad Khalid Mojadidi, MD, Ninel Hovnanians, MD, Michael R. Kaufmann, MD, and James A. Hill, MD, FACC

A 55-year-old woman with a history of chronic bronchitis, Clostridium difficile colitis, and alcohol and tobacco abuse was admitted with altered mentation, hyponatremia, and necrotizing right-upper-lobe pneumonia. She was started on cefepime and vancomycin; metronidazole was added for colitis. A resting electrocardiogram (ECG) showed sinus tachycardia with a QS pattern in the precordial leads, normal intervals, and small T-wave inversions in leads V₅ and V₆. Four days later, significant changes in her baseline telemetry rhythm prompted a repeat 12-lead ECG; the patient’s pulse rate was 75 beats/min with a QT interval of 720 ms and QTc of 746 ms (Fig. 1). Her troponin T level was <0.03 ng/mL, and she had no new symptoms. Her medications at that time were aspirin, metoprolol, lisinopril, cefepime, atorvastatin, pantoprazole, metronidazole, oral vancomycin, and subcutaneous heparin. Her potassium level was 2.9 mEq/L, and her magnesium level was 1.6 mEq/L. An echocardiogram showed severe left ventricular dysfunction with wall motion that suggested stress-induced cardiomyopathy.

Case #3 - Heart Block in a Pacemaker: Does This Mean Trouble?

by Mark Pollet, MD, Yochai Birnbaum, MD, and Alireza Nazeri, MD

We present a finding in a 61-year-old woman whose St. Jude Medical dual-chamber permanent pacemaker had been implanted to treat symptomatic bradycardia. The pacemaker, programmed in DDD mode, had a lower rate limit of 60 beats/min and an upper limit of 120 beats/min, a paced atrioventricular (AV) delay period of 250 ms, and a sensed AV delay period of 225 ms.

Case #2 - Evaluation of Suspected Device Malfunction on ECG

by Luke Cunningham, MD, Henry D. Huang, MD, and Yochai Birnbaum, MD

A 62-year-old man with nonischemic cardiomyopathy, a history of Boston Scientific biventricular implantable cardioverter-defibrillator placement (in 2011), ventricular tachycardia after radiofrequency ablation (April and November 2014), paroxysmal atrial fibrillation, and severe mitral regurgitation presented with acute exacerbation of heart failure. A resting electrocardiogram (ECG) showed normal sequential atrioventricular (AV) pacing at a heart rate of 63 beats/min. Baseline device settings were DDD with a lower rate of 60 beats/min, an upper rate of 115 beats/min, a minimum sensed AV delay of 135 ms, and a minimum paced AV delay of 180 ms. The patient underwent mitral valve replacement. Three days later, the pacemaker rate was increased to 80 beats/min, and an ECG showed pacing concomitantly within the T wave in beats 5 and 13 of the rhythm strip (Fig. 1).

Case #1 - Pacing on the T Wave: What Is the Cause?

by Amir Gahremanpour, MD, Yochai Birnbaum, MD, Tracy A. Holt, BS, and Mohammad Saeed, MD

We present the case of a 50-year-old man who had a dual-chamber pacemaker that was implanted because of symptomatic bradycardia. The pacemaker was programmed in a DDD mode, with a lower rate of 70 beats/min; upper rate, 120 beats/min; paced atrioventricular (AV) delay, 180 ms; sensed AV delay, 150 ms; and V-blanking period, 200 ms.