Trauma is the leading cause of death and disability among young people in the United States.1-3 Cardiac and great vessel injuries are common contributors to the morbidity and mortality of severely injured patients.4 Injury to the heart and thoracic aorta can be broadly divided into penetrating or blunt mechanisms.

Penetrating Cardiac Injuries

Penetrating injury to the heart must be suspected with any missile or knife wound to the thorax or upper abdomen. The anteriorly positioned right ventricle is most frequently injured followed by the left ventricle and right atrium.5 Other potentially injured structures include the interatrial or interventricular septum, coronary arteries, valves, subvalvular apparatus, and conduction system.6 Low-velocity injuries, such as stab wounds, produce damage commensurate to the structure penetrated and size of the defect. High-velocity missiles produce injury beyond the region of myocardial penetration secondary to concussive effects and are more frequently lethal.7-10

The primary manifestations of cardiac penetration are hemorrhage and tamponade. Valve or coronary injury may, of course, produce acute valvular incompetence or myocardial infarction. Stab victims often present with tamponade when clot and surrounding pericardial fat partially seal the pericardial defect. Injuries to the left ventricle more commonly result in overt hemorrhage. Patients presenting with tamponade may have a survival advantage, with mortality rates as low as 8% in experienced trauma centers.7 Early diagnosis is critical to survival, and this is only possible with a high index of suspicion, bearing in mind that patients with potentially fatal wounds can be stable at presentation. Echocardiography can confirm the diagnosis of cardiac injury, but the lack of an effusion does not disprove injury.11 The diagnostic gold standard, short of exploration, is a subxiphoid window.

Management of penetrating wounds to the heart depends on the stability of the patient. If the patient presents with a recent loss of vital signs or in a moribund state, a left anterior thoracotomy performed in the emergency department is potentially lifesaving. Emergent thoracotomy may salvage as many as 20% of unstable or pulseless patients who have isolated penetrating trauma to the heart, but results are less favorable with missile wounds.12,13 Most cardiac wounds can be repaired through a left thoracotomy. Additionally, the thoracic aorta can be compressed or clamped to improve cerebral and cardiac perfusion while volume is restored. More stable patients are transported to the operating room, where a median sternotomy is the preferred approach. A sternotomy allows adequate exposure of all cardiac structures and permits rapid institution of cardiopulmonary bypass when required. Most injuries are repaired with simple pledgeted sutures using finger control to stop bleeding once identified. Coronary artery injuries are common, and the surgeon must use his or her judgment regarding coronary artery bypass versus ligation. An effort should be made to bypass large epicardial vessels, whereas smaller terminal branches or side branches can be ligated. The principal objective is to relieve tamponade and stop life-threatening hemorrhage. Further procedures, once again, require individualized surgical judgment based on the severity of the lesion and the physiologic significance on echocardiogram.

Blunt Cardiac Injury

Blunt cardiac injury results from either a rapid deceleration mechanism or a direct blow to the precordium. Resulting injuries include cardiac contusion, valve disruption, atrial or ventricular septal defects,14 or frank cardiac rupture. Once again, because of its anterior position, the right ventricle is the chamber most frequently involved. Cardiac rupture is a common mechanism of death in blunt trauma,15 with survival after medical care being uncommon. In patients reaching medical care with vital signs, however, a reasonable survival rate can be expected if cardiac injury is promptly recognized and operated on.16 Those surviving cardiac rupture more frequently have injuries to the right heart.17 Myocardial contusion encompasses a spectrum of injuries. In its mildest form, cardiac contusion results in mild epicardial ecchymosis without functional significance. More severe contusion can cause muscular injury, dysfunction, and infarction. The true incidence of myocardial contusion following blunt trauma is difficult to discern and is dependent on the definition and method of diagnosis. There is no universal agreement on this matter. It is important to note that severe myocardial injury can occur with little evidence of external chest trauma.

All patients who have a significant mechanism of injury should have a screening electrocardiogram (ECG). Findings suggestive of cardiac contusion include nonspecific ST and T wave changes. Arrhythmias such as atrial fibrillation, atrial flutter, and premature ventricular complexes are also common and are usually self-limiting. Ventricular tachycardia and fibrillation are uncommon in patients surviving to the hospital. With a normal ECG in an otherwise uninjured patient, the risk of complications is low. Serial cardiac enzyme measurements are nonspecific for the diagnosis of myocardial contusion in the blunt injury patient.18 In the patient who remains unstable or responds poorly to standard resuscitative efforts, echocardiography is indicated to look for regional wall motion abnormalities or structural defects.

The management of myocardial contusion is often expectant, particularly in the patient who remains hemodynamically stable after treatment of concurrent injuries. Arrhythmias are treated with standard agents for rate control and suppression of ectopy as well as optimization of electrolytes. In cases of severe ventricular dysfunction and low cardiac output, inotropic support is appropriate with perhaps less concern for extension of injury than with a primary ischemic event. If inotropic support does not produce satisfactory improvement, intra-aortic balloon counterpulsation should be considered.

Valve injury following blunt trauma is uncommon. The aortic valve is most frequently involved and can result from commissural avulsion, leaflet tears, or aortic dissection, all resulting in acute aortic insufficiency.19-21 Isolated injury of the mitral valve is less common and most frequently involves rupture of the papillary muscle or chordal apparatus. Tricuspid valve injury is more commonly reported than mitral injury perhaps because the latter is frequently fatal. Tricuspid valve injury may become evident at a time remote from the injury as right heart failure develops.22,23

Delayed Sequelae of Cardiac Injury

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