The QT interval—a measure of the duration of the overlapping action potentials from two billion ventricular muscle cells—has fascinated physiologists since the dawn of electocardiography. Too long or too short, it can be a harbinger of ventricular arrhythmias and sudden death. Sensitive to electrolytes, drugs, and autonomic tone, susceptible to congenital ionic channel mutations, difficult to… Continue reading Hacking the QTc