BACKGROUND: Sudden death due to low-energy blunt trauma to the precordium 
(commotio cordis) has been described with a variety of sporting objects. 
However, the risk of ventricular fibrillation (VF) relative to the shape of the 
impact object is not known.
OBJECTIVE: The objective of the current experiment is to test whether the impact 
object shape is a clinical variable that affects the risk for commotio cordis.
METHODS: In a juvenile swine model, impacts were given in random order with two 
different spherical shapes (72 mm diameter, equivalent to a baseball; 42 mm 
diameter, equivalent to a golf ball) and a flat round object 72 mm in diameter. 
Objects were equal in weight (150 g), thrown at 30 mph, and gated to the 
vulnerable portion of the cardiac cycle.
RESULTS: Sixteen swine received 144 impacts. The flat object did not cause VF (P 
= .01 compared with the two spherical objects), nonsustained VF, ST elevation, 
or bundle branch block. The smaller diameter sphere caused VF in nine of 48 
impacts (19%), and the larger diameter sphere caused VF in five of 48 impacts 
(10%; P = .25). The smaller diameter sphere was associated with a greater 
increase in left ventricular pressure (P <.0001 and P = .001 compared with 
larger sphere only) and a higher likelihood of ST segment elevations (P <.001 
and P = .08 compared with larger sphere only) and bundle branch block (Fisher's 
exact P = .008, and Fisher's exact P = .18 compared with larger sphere only).
CONCLUSION: The shape of the projectile markedly influences the risk of VF from 
chest wall impact. This effect is likely mediated via a greater increase in left 
ventricular pressure with smaller diameter objects. Spreading the impact force 
over a larger area may decrease the risk of sudden death and has implications 
for the design of protective athletic equipment.