Trauma is the leading cause of death and disability among young people in the United States.1,2,3 Thoracic injures account for 20% to 25% of deaths from trauma, and contribute to 25% to 50% of the remaining deaths. Thus thoracic injures are a contributing factor in up to 75% of all trauma-related deaths.4 Cardiac and great vessel injuries are common contributors to the morbidity and mortality of severely injured patients.5 Causes of 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 mechanism of injury may be categorized as low, medium, or high velocity. Knife wounds are low velocity, shotgun injuries are medium velocity, and high-velocity injuries include bullet wounds caused by rifles and wounds resulting from military and civilian weapons. The amount of tissue damage is directly related to the amount of energy exchange between the penetrating object and the body part.4
Traumatic cardiac penetration injuries are highly lethal at 70% to 80%. The anteriorly positioned right ventricle is most frequently injured followed by the left ventricle, right atrium, and left atrium (Table 104–1).6 Other potentially injured structures include the interatrial or interventricular septum, coronary arteries, valves, subvalvular apparatus, and conduction system.7 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.8,9,10,11
TABLE 104–1.Spectrum of Penetrating Cardiac Injury by Anatomic Location50 |Favorite Table|Download (.pdf) TABLE 104–1. Spectrum of Penetrating Cardiac Injury by Anatomic Location50
|Right ventricle ||43% |
|Left ventricle ||34% |
|Right atrium ||16% |
|Left atrium || 7% |
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.8 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.12 The diagnostic gold standard, short of exploration, is a subxiphoid window.
Management of penetrating wounds to the heart depends on the ...