25. Cardiac trauma
- Introduction. All regions of the heart may be damaged by penetrating or nonpenetrating chest injuries. Many cardiac injuries are overlooked transiently or permanently because of trauma to other parts of the body that demands immediate attention. Thus, many cardiac contusions undoubtedly resolve without notice in individuals with multiple traumatic injuries. Cardiac traumatic injuries can be rapidly fatal; for example, laceration or disruption of the pericardium, myocardium, and/or coronary artery or vein frequently results in hemopericardium and tamponade.
Swift recognition of the cardiac injury combined with pericardiocentesis and surgical repair of the lesion is required if the patient is to survive. Table 25-1 lists some of the many forms of traumatic cardiac injury. Myocardial rupture, contusion, and laceration account for almost 90% of deaths secondary to nonpenetrating cardiac trauma.
- History. Any penetrating or nonpenetrating chest injury can involve the heart.
The patient may not notice or be capable of reporting chest trauma. If the injury occurs in the hospital (e.g., perforation of a cardiac chamber by a cardiac catheter) in a conscious patient, the individual often complains of severe chest discomfort. Recurrent syncope may be reported in someone with tamponade or heart block after cardiac trauma. Heart failure, either immediate or delayed, may occur in individuals with valvular disruption, arteriovenous fistula, or myocardial infarction (MI) secondary to coronary arterial injury.
A delayed form of pericarditis similar in character and natural history to post-MI pericarditis occurs in approximately 20% of patients with penetrating wounds of the heart. This syndrome can also occur in patients with nonpenetrating cardiac trauma. All patients with penetrating and nonpenetrating injury to the anterior chest should undergo evaluation for cardiac trauma.
- Physical examination. Systemic and cardiovascular findings in patients with cardiac trauma depend on the type of injury sustained. Thus, patients with acquired ventricular septal defect (VSD) may have a loud systolic murmur, a third heart sound (S3), and signs of left or right ventricular failure. Patients with aortic disruption may demonstrate pulse inequalities; patients with pericardial, myocardial, or coronary arterial lacerations often present with cardiac tamponade (see Chapter 19). Patients with pericarditis or pericardial tears or lacerations may have audible precordial rubs. Some of the physical findings in patients with cardiac traumatic injuries are as follows (not all findings are present in all forms of cardiac injury):
Tachycardia (hypovolemia, tamponade)
Bradycardia (conduction system injury)
Hypotension (hypovolemia, tamponade)
Jugular venous distention (right ventricular failure, tamponade)
Signs of left ventricular failure: tachypnea, rales, pleural effusion, S3 (aneurysm, infarction, valvular disruption, VSD)
Signs of right ventricular failure: jugular venous distention, hepatomegaly, peripheral edema (same conditions producing left ventricular failure)
Signs of cardiac tamponade: tachycardia, hypotension, jugular venous distention, small quiet heart
Systolic cardiac murmurs (mitral or tricuspid valvular injury, VSD)
Diastolic cardiac murmurs (pulmonic or aortic valvular injury, aortic–left ventricular fistula)
Continuous cardiac murmurs (arteriovenous fistula, fistula from aorta to atrium or right ventricle)
Rub (pericarditis, pericardial tear or laceration)
Pulse inequalities (aortic disruption)
Signs of splenic, renal, or cerebral infarction (foreign body or thrombotic embolism)
- ECG. Atrial and ventricular arrhythmias are common in patients with cardiac trauma. Individuals with myocardial contusions often have the same ventricular arrhythmias (ventricular premature beats, ventricular tachycardia, ventricular fibrillation) seen in patients with acute MI. First-, second-, or third-degree heart block is seen with conduction system injuries. Nonspecific ST–T changes or infarction patterns are found in patients with myocardial contusion or laceration. The S–T segment changes of pericarditis may be present, or the ECG may be normal. Tall, peaked precordial T waves often are seen in patients with hemopericardium. ECG findings in patients with cardiac traumatic injuries are the following (not all findings are present in all forms of cardiac injury):
Atrial and ventricular arrhythmias
Bundle branch blocks
First-, second-, third-degree heart block
Nonspecific ST–T changes
Diffuse S–T segment elevation (pericarditis)
Tall, peaked precordial T waves (hemopericardium)
- Chest x-ray examination. Roentgenographic findings in patients with cardiac trauma include (i) cardiomegaly secondary to hemopericardium or pericardial effusion; (ii) signs of left ventricular failure (vascular redistribution, interstitial or alveolar edema, pleural effusion) secondary to myocardial contusion, ventricular aneurysm, valvular disruption, intracardiac fistula, or VSD; and (iii) mediastinal widening secondary to aortic disruption. Other roentgenographic findings that may be observed in patients with chest trauma include fractured ribs, pneumothorax, hemothorax, or pulmonary hemorrhage. Chest x-ray findings in patients with cardiac trauma are as follows:
Cardiomegaly (effusion or hemopericardium)
Left ventricular failure (vascular redistribution, interstitial or alveolar pulmonary edema, pleural effusion)
Mediastinal widening (aortic disruption)
Tracheal deviation (disruption)
Pulmonary infiltrates (pulmonary hemorrhage)
- Laboratory tests. Increased serum activities for various cardiac biomarkers are observed in patients with cardiac contusion. The time course of these enzyme elevations resembles that for MI. Because skeletal muscle trauma can result in higher serum levels of glutamic oxaloacetic transaminase, lactic dehydrogenase, and creatine phosphokinase (CK), these biomarkers are not useful in the diagnosis of cardiac contusion. Measurement of blood levels of cardiac specific troponin is the preferred method of identifying myocardial injury following cardiac trauma. An acceptable alternative that is not as sensitive or specific is determination of blood levels of CK-MB isoenzyme fraction.
- Echocardiography. Blood or effusion in the pericardial space can be detected by echocardiography. Regurgitant valvular lesions, aortic-atrial or ventricular fistulae, and VSD can produce left ventricular dilatation or hypercontractility in the echocardiogram. Valvular regurgitation and shunt flow can be detected and quantitated by a Doppler study. Myocardial contusion and MI result in regional hypokinesis or akinesis.
- Radionuclide studies. Regions of myocardial injury can often be identified by myocardial scintigraphy with technetium 99m–labeled antimyosin antibodies or technetium 99m–labeled pyrophosphate. Ventricular aneurysms can be identified by radionuclide ventriculography, and intracardiac shunts secondary to fistulae or VSD can be identified and measured by radionuclide angiocardiography.
- Catheterization and angiography. A variety of hemodynamic findings can be observed in patients with cardiac trauma, depending on the type of injury incurred. Patients may demonstrate the pathophysiologic patterns of tamponade (see Chapter 19), left ventricular failure, right ventricular failure, acute VSD (see Chapter 15), acute valvular regurgitation (see Chapter 16), or MI. VSDs, fistulae, and ventricular or aortic aneurysms can be visualized by angiography. Aortic disruption usually occurs just above the aortic valve or just distal to the left subclavian artery.
- Protocol for the diagnosis of cardiac trauma
- Because of the many types of cardiac trauma with differing natural histories, it is hard to envision one diagnostic protocol for all lesions. Fig. 25-1 is a suggested diagnostic protocol for patients suspected of having cardiac traumatic injuries (dashed arrows indicate optional steps). There are a number of branches to this protocol corresponding to the diagnostic strategies used in the various types of cardiac traumatic injury. Patients with life-threatening injuries such as hemopericardium or aortic rupture may require emergency surgical treatment without any diagnostic information other than a brief history and physical examination.
Fig. 25.1. Protocol for the diagnosis of cardiac trauma. Dashed arrow indicates optional procedures.
- Criteria used in the diagnosis. Cardiac traumatic injury is diagnosed in patients with a history of trauma, usually involving the chest, in whom physical examination, ECG, or chest roentgenogram discloses an abnormality consistent with cardiac trauma. Confirmation of the diagnosis depends on the demonstration of at least one of the following: (i) elevated serum activity of troponin or CK-MB, (ii) pericardial fluid by echocardiography, (iii) myocardial injury by radionuclide scintigraphy, and (iv) anatomic abnormality such as valvular regurgitation, septal defect, fistula, or aortic or ventricular rupture by echo-Doppler study or catheterization after chest trauma.
- Differential diagnosis. Because of the setting in which the diagnosis of cardiac trauma is considered, it is unlikely to be confused with other entities. Therefore, diagnostic problems revolve around identifying specific lesions that result from the traumatic event. Pericardial injuries present with prominent rubs or cardiac tamponade. Echocardiography demonstrates fluid in the pericardial space. Myocardial contusion resembles infarction in natural history; presenting complaint; and serologic, physical, ECG, and roentgenographic findings. Residual left ventricular damage is less with contusion than with infarction. Fistulae, VSD, and valvular disruption present with murmurs with or without evidence of left or right ventricular failure. Aorta-to–right heart fistulae produce continuous murmurs and right ventricular failure. VSD and atrioventricular valvular injury with resultant regurgitation cause prominent systolic murmurs, whereas pulmonic and aortic valvular disruption and regurgitation produce diastolic murmurs. Patients with injury to the conduction system usually have some form of heart block. Those with aortic rupture often complain of severe chest and midscapular pain associated with dyspnea, increased pulse amplitude, and upper extremity hypertension. Identification of cardiac traumatic injuries occurs only if the physician maintains a high index of suspicion when facing patients who have suffered an episode of chest trauma.
- Medical treatment. Medical therapy may involve only preoperative volume replacement in a patient with aortic rupture awaiting momentary operative repair. On the other hand, the therapy of cardiac contusion is completely medical, resembling that of non–Q wave myocardial infarction.
- Arrhythmias. Patients with cardiac traumatic injuries frequently manifest atrial or ventricular arrhythmias. These usually can be controlled with routine antiarrhythmic regimens (see Chapters 3 and 15).
- Heart failure. Left and right ventricular failure usually can be managed with conventional antifailure regimens, including vasodilators, diuretics, and, on occasion, digitalis.
- Posttraumatic pericarditis. The treatment of posttraumatic pericarditis resembles that for postinfarction pericarditis. Salicylates, ibuprofen, or other nonsteroidal antiinflammatory agents are used initially, followed by corticosteroids if pericarditis persists (see Chapter 19).
- Heart block. Transient or permanent conduction disturbances may require temporary or permanent transvenous pacing.
- Cardiac tamponade. Tamponade is usually the result of hemopericardium in patients with cardiac trauma. Pericardiocentesis should be performed once or several times while the patient is being readied for thoracotomy.
- Cardiac traumatic injuries often demand urgent or delayed surgical repair. It is best if repair can be delayed a few weeks to allow for some healing; however, many patients (e.g., those with aortic rupture) require emergency surgical intervention. Patients with valvular disruption may need valve replacement, although repair of the valve is successful in many patients. Fistulae and VSDs usually must be closed unless the flow through them is small. Spontaneous closure of small traumatic VSDs can occur.
- Laceration or rupture of a coronary vessel, a cardiac chamber, or the aorta requires urgent surgical repair. If a coronary artery has been injured, MI can be ameliorated or prevented if coronary bypass or coronary arterial stenting is performed promptly.
- Patients with permanent second- or third-degree heart block should receive a permanent pacemaker.
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