An animal model to examine the response to environmental stress as a factor in sudden cardiac death

Sudden cardiac death is the leading mode of death in adults in the United States. While it appears intimately associated with coronary artery disease, the factors that render some subjects vulnerable to sudden cardiac death, while others with the same coronary disease do not die suddenly, are unknown. An approach is described which considers that sudden cardiac death represents a separate syndrome of coronary artery disease within certain vulnerable subjects. It is suggested that the response to psychosocial stress in vulnerable subjects results in deleterious cerebral cortical influences on the autonomic control of the heart which render it more vulnerable to ischemia-induced ventricular fibrillation. Studies in the pig, an animal known to be susceptible to sudden death resulting from an environmental stress, demonstrate that cerebral cortical influences on autonomic centers play a central role in vulnerability to ventricular fibrillation after coronary artery occlusion. In this model, the incidence of ventricular fibrillation can be reduced by psychologic adaptation of the animal to his environment, cryoblockade of frontal cortical brain stem pathways and by central administration of propranolol. The relative role of adrenergic and cholinergic innervation of the heart is an important consideration.