Abrupt deceleration associated, with vehicle crash environments commonly produces rupture of the heart and great vessels of the thoracic cavity. A study of the mechanism of these lesions has yielded a series of high-speed radiographs obtained at selected time intervals during controlled deceleration. Lightly anesthetized Beagle dogs were rigidly restrained in form-fitted stafoam capsules and subjected to ± Gz impact on the Bopper and Daisy Decelerator. Flash radiographs were taken with a Flexitron Model 233 (300 kv) X-ray pulser initiated by microswitch on the decelerator track.

Preliminary data indicate that the heart undergoes considerable inertial movement during deceleration. These observations suggest that the mechanism of vessel rupture may involve mechanical tearing from violent displacement of the heart and diaphragm.

(The experiments reported herein were conducted according to the "Principles of Animal Care" established by the National Society for Medical Research.)