Thebroken heart: noninvasive measurement ofcardiac autonomic tone

Raconteurs relate reports ofsudden death under emotional stress, frequently witharetributional message. However, florid embellishments give these tales apochryphal status inserious circles. Recently, interest inthis phenomenon hasrevived. Taggart etal.1 demonstrated increased ventricular ectopy andplasma catecholamine levels instressed normal individuals without heart disease, andthe severity ofventricular arrhythmias increases under these circumstances inknowncardiac cases.2 Catecholamine infusion inhumansalters cardiac repolarization andgenerates arrhythmias.3 Thedemonstration ofcardiac chronotropic organization within theratinsular cortex may indicate how emotional stresses alter cardiac autonomic tone.4 Thisarea, inhumanslying beneath thefrontoparietal andtemporal opercula, hasprofuse reciprocal connectivity withthelimbic system whichispredominantly involved inemotional control.5 Prolonged stimulation ofcardiac insular sites produces repolarization abnormalities andventricular ectopy coupled withincreased plasma norepinephrine levels andasystolic death.6 Shifts inautonomic tonefromparasympathetic tosympathetic predominance caninduce vent