NONPENETRATING TRAUMA



Blunt chest trauma is especially common after steering wheel impact from an automobile acci­dent. It may produce myocardial contusion, re­sulting in myocardial hemorrhage and at times some degree of necrosis. Often there is little or no residual myocardial scar once healing is com­plete. Large contusions may lead to myocardial scars, cardiac or septal rupture, congestive heart failure, or formation of true or false aneurysms. Necrosis or hemorrhage involving the cardiac conduction system can produce intraventricular or atrioventricular block. Coronary artery lacera­tion, valvular damage, or pericardial tears may oc­casionally occur after blunt trauma. The chest pain of myocardial contusion is similar to that of myocardial infarction and is often confused with musculoskeletal pain from the chest trauma. The electrocardiogram at the time of injury may show a diffuse injury pattern similar to that of pericar­ditis. Later, the electrocardiogram may reveal se­rial development of Q waves similar to that of acute myocardial infarction if significant necrosis has occurred. Bradyarrhythmias and tachyar­rhythmias are common. Contractile abnormalities are usually not severe unless concomitant injury to a valve or the septum has occurred. The MB fraction of creatine kinase is elevated. Myocardial contusion is usually treated similarly to myocar­dial infarction with initial monitoring and sub­sequent progressive ambulation. Anticoagulants should not be administered to patients with my­ocardial contusion. If the patient survives the acute-episode,, his long-term prognosis is usually good, although late complications such as ven­tricular arrhythmias occasionally occur.

Rupture of the aorta is a common consequence of blunt trauma. It most commonly occurs just dis­tal to the take-off of the left subclavian artery. The patient may complain of pain in the back or chest similar to that of aortic dissection. The chest x-ray usually reveals widening of the mediastinum. Many patients demonstrate increased arterial pressure in the upper extremities and decreased arterial presure and pulse pressure in the lower extremities. Signs of decreased renal or spinal cord perfusion may become evident. The diag­nosis is usually confirmed by aortography, and the treatment is surgical.