The heart and its tributaries are encased in the chest cavity, composed of the manubrium, sternum, clavicle, rib cage, and vertebral bodies. This rigid chassis, for the most part, provides adequate protection against small impacts/injuries. Severe trauma requiring intervention occurs by penetrating or blunt mechanisms. Firearms often result in direct injury to the heart and great vessels, in the path of destruction.
The bony structures, interestingly, can also provide unique forms of injuries as they cause a ricocheting of bullets or alter vectors of the original direction of penetration. Blunt forces can lead to crushing, traction, and torsion injuries to the heart from deceleration forces. Penetrating trauma to the great vessels can lead to immediate exsanguination or pattern of injury similar to blunt trauma including pseudoaneurysm, partial transection with intimal flap, thrombosis, and propagation.
Cardiac injury may account for 10% of deaths from gunshot wounds.1 Penetrating cardiac trauma is a highly lethal injury, with relatively few victims surviving long enough to reach the hospital. In a series of 1,198 patients with penetrating cardiac injuries in South Africa, only 6% of patients reached the hospital with any signs of life.2 With improvements in organized emergency medical transport systems, up to 45% of those who sustain significant heart injury may reach the emergency department with signs of life. It is somewhat frustrating however to note the overall mortality for penetrating trauma has not changed much even in the major trauma centers.3
Blunt cardiac injuries have been reported less frequently than penetrating injuries.1 The actual incidence of cardiac injury is unknown because of the diverse causes and classifications. Thoracic trauma is responsible for 25% of the deaths from vehicular accidents of which 10–70% of this subgroup may have been the result of blunt cardiac rupture. There continues to be tremendous confusion as the term blunt cardiac injury/cardiac contusion is applied to a wide spectrum of pathology.
Penetrating Cardiac Injury
Penetrating trauma is a common mechanism for cardiac injury, with the predominant etiology being from firearms and knives4 (Table 26-1). The location of injury to the heart is associated with the location of injury on the chest wall. Because of an anterior location, the cardiac chambers at greatest risk for injury are the right and left ventricles. In a review of 711 patients with penetrating cardiac trauma, this series noted 54% sustained stab wounds and 42% had gunshot wounds. The right ventricle was injured in 40% of the cases, the left ventricle in 40%, the right atrium in 24%, and the left atrium in 3%. The overall mortality was 47%. This series noted one third of cardiac injuries involved multiple cardiac structures.4 More complicated intracardiac injuries involved the coronary arteries, valvular apparatus, and intracardiac fistulas (such as ventricular septal defects). Only 2% of patients surviving the initial ...