Electromechanical dissociation and its possible role in sudden cardiac death

Electromechanical dissociation is a rare but important cause of death in some patients with cardiac ischemia. It is a well characterized syndrome involving loss of contractile function of the heart without arrhythmia. Several other clinical syndromes, including massive pulmonary embolism and cardiac rupture, can mimic electromechanical dissociation, so its incidence is difficult to estimate. Experimental studies of early ischemic contractile failure show preservation of adenosine triphosphate levels, and of the calcium ion release mechanism. Intracellular acidosis is temporarily correlated, but direct causality cannot be assigned to the acidosis because of the lack of necessary direct studies. The role of the autonomic nervous system in triggering the sequence of events leading to electromechanical dissociation is unclear and is a promising area for further study.