Central origin of decreased heart rate variability in patients with cardiovascular diseases.

Sympathetic activity influences the total power of the heart rate variability spectrum. Decreased heart rate variability and increased sympathetic tone have been related to poor prognosis and an increased risk of sudden cardiac death in patients with myocardial infarction, congestive heart failure or hypertension. On the basis of recent experimental data, I propose that these disease states are associated with altered spectral characteristics of the central sympathetic activity generated within rostral ventrolateral medulla neurones, which subsequently leads to decreased heart rate variability and increased systemic sympathetic tone.