Cardiac Alternans: From Bedside to Bench and Back

Cardiac alternans arise from dynamical instabilities in the heart's electrical and calcium cycling systems and often precedes ventricular arrhythmias and sudden cardiac death. In this review, the study integrates clinical observations with theory and experiment to paint a holistic portrait of cardiac alternans: the underlying mechanisms, arrhythmic manifestations and electrocardiographic signatures. The major conclusion is that alternans is not only a predictor but also a causal mechanism of potentially lethal ventricular and atrial arrhythmias across the full spectrum of arrhythmia mechanisms that culminate in functional reentry, although less important for anatomic reentry and focal arrhythmias.