The clinical case, says 64-year-old woman with dilated cardiomyopathy, her left ventricular ejection fraction is 25 percent. She has paroxysmal atrial fibrillation and a dual-chamber ICD in place, treated with lisinopril, metoprolol, digitalis, furosemide, and she comes to clinic after experiencing two implanted defibrillator shocks. Her only complaints at the time are malaise, dizziness, and shortness of breath. The ICD interrogation reveals multiple episodes of tachycardia. Two were associated with shocks that were delivered from the device. The baseline ECG is shown in figure 3.1. Let me show that to you for just a couple of seconds. There were several monitor strips recorded and they are shown in Figure 3-2, and I'll show those to you as well. As noted, intermittent episodes of this rhythm were observed in this patient. Her electrolytes were unremarkable. BUN was 35 milligrams per deciliter and the creatinine was 1.9 milligrams per deciliter. What is the most likely cause of the tachycardia? A, digitalis-induced delayed after depolarizations. B, exaggerated dispersion of repolarization due to left ventricular dysfunction. C, inappropriate shocks due to atrial fibrillation with rapid ventricular response. D, tachycardia-induced tachycardia with AF inducing VT. Again, let me give you a couple of minutes to consider this, and we'll go back to the figures and let you have a look at those as well. The baseline electrocardiogram and the monitor strips.

dilated cardiomyopathy

dual-chamber ICD

tachycardia

defibrillator shocks

digitalis-induced depolarizations