12 - The etiology of sudden death

Summary

Definition

Sudden death is natural death, heralded by loss of consciousness within 1 hour of the onset of acute symptoms. The time and mode of death are unexpected. This definition is meant to satisfy medical and scientific considerations as well legal and social concerns. Included within this construct are four temporal elements: (a) prodromes, (b) onset of terminal event, (c) cardiac arrest, and (d) progression to biological death. Prodromes, if any, are new or worsening symptoms that begin during an arbitrarily defined period of up to 24 hours before the onset of cardiac arrest. The 1-hour time period described in the definition refers to the duration of the terminal event leading to cardiac arrest. Following cardiac arrest – the clinician's synonym for sudden death, biological death may ensue within minutes, or alternatively, due to community-based interventions and life support systems, may be delayed for a long period of time and even aborted altogether. Nonetheless, for legal, forensic, and certain social considerations, biological death is used as the absolute definition of death.

Epidemiology and Causation

A large prospective cohort study – the Framingham study – observed that over a 26-year period, 13% of all deaths were sudden in nature as defined by death within 1 hour of the onset of symptoms. In the Western hemisphere, cardiac causes currently predominate in sudden deaths among adults. One large retrospective analysis of death certificates in the United States reported that 88% of sudden deaths were due to cardiac causes. Hence, an estimated 300 000 sudden cardiac deaths occur annually in the United States, accounting for about 50% of all deaths due to cardiovascular disease.