The role of the central nervous system in sudden cardiac death: heartbeat dynamics in conscious pigs during coronary occlusion, psychologic stress and intracerebral propranolol.

Electrocardiograms were recorded in conscious pigs during psychological stress (touching), left anterior descending coronary artery occlusion, intracerebral levopropranolol (0.05 mg/kg), and their respective controls. The R-R intervals were evaluated with both a deterministic measure (point correlation dimension) and a stochastic one (mean). Only the deterministic measure was sensitive to between-subject responses (P < .01), whereas both measures were sensitive to within-subject changes. The results are explained by a deterministic model of heartbeat generation.