From Ask Dr Wiki
- Sudden cardiac death accounts for more than 300,000 deaths annually in the United States.
- Defined as sudden cardiac death secondary to relatively innocent chest wall impact.
- Commonly compared to R-on-T and shock-on-T phenomena for VF induction.
- More than 180 cases have been reported.
- Clinical findings include young age (average age 14 years) and male gender (>95%).
- Impact objects have included baseballs, softballs, hockey pucks and rigid body parts.
- Impact must occur during a very narrow window which results in ventricular depolarization during phase 2 of repolarization.
- Impact leads to inhomogeneity of repolarization leading to activation of myocardial substrate occuring in a nonuniform manner culminating in VF.
- Only impacts occurring 0-40msec before the peak of the T wave cause VF in swine models. Interestingly, the vulnerable window appears to be narrower than the vulnerable window with experimentally induced VF from shock on T.
- Chest wall protection does not prevent sudden death.
- With early resuscitation and defibrillation, prognosis is good.
