The spectrum of blunt cardiac trauma ranges from asymptomatic myocardial contusion to fatal cardiac arrhythmias and/or cardiac rupture. Although cardiac rupture is common in fatal traffic accidents, these patients rarely reach hospital care. Insignificant blunt cardiac injury during sports may cause fatal arrhythmia in teens. Penetrating cardiac trauma is fairly common in the United States, encountered frequently in major urban centers. Most cases are dead at the scene and never reach hospital. The incidence of cardiac sequelae in survivors is high, and these patients should be evaluated with early and late echocardiography to detect anatomic or functional cardiac involvement.
Key points
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Blunt cardiac trauma includes a wide spectrum of conditions, ranging from asymptomatic myocardial contusion to fatal cardiac arrhythmias and/or cardiac rupture.
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Blunt cardiac rupture is a common cause of instant death in traffic injuries.
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The role of cardiac biomarkers remains controversial; however, normal electrocardiogram and troponin levels may rule out a significant blunt cardiac trauma in most cases.
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Significant chest trauma, especially in the presence of multiple rib or sternal fractures or lung contusions, is associated with a high incidence of cardiac involvement.
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Insignificant blunt cardiac injury during sports may cause fatal arrhythmia in teens.
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The diagnosis of penetrating cardiac injury is usually clinical. The Focused Assessment with Sonography in Trauma examination is the most useful and reliable bedside investigation.
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Patients with penetrating cardiac trauma or blunt cardiac rupture presenting with cardiac arrest or imminent cardiac arrest should be managed with an emergency-room resuscitative thoracotomy.
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Survivors of penetrating cardiac injuries should be evaluated with early and late echocardiography to detect anatomic or functional cardiac sequelae.
Introduction
Trauma is overall the fourth most common cause of death and the leading cause of death in individuals younger than 40 years, accounting for 5 million fatalities worldwide on an annual basis. Thoracic trauma is directly responsible for 25% of trauma deaths, and contributes indirectly to another 25% of trauma-related mortalities.
Thoracic trauma may result in a wide spectrum of cardiac lesions, ranging from an asymptomatic myocardial contusion to a rapidly fatal cardiac tamponade or exsanguination caused by a transmural laceration. The reported incidence of cardiac injuries varies widely, with 15% to 76% of patients sustaining major chest injury depending on whether the diagnosis has been made clinically or on autopsy. Nevertheless, in penetrating trauma and in victims who die at the scene of the injury, the incidence of cardiac involvement is much higher.
Cardiac trauma is uncommon in the pediatric population in the United States. Kaptein and colleagues, in a National Trauma Data Bank (NTDB) review, reported that only 0.03% of all pediatric trauma cases (age <8 years) had a documented cardiac injury. The vast majority of cardiac lesions in this population, however, occurred in teenagers (73%). The American Association for the Surgery of Trauma (AAST) has defined the severity of cardiac injuries in their organ injury scale for standardization purposes ( Table 1 ). This article reviews the management of cardiac trauma under the following categories:
- 1.
Blunt cardiac injury (BCI)
- 2.
Penetrating cardiac injury (PCI)
| Grade | Description of Injury |
|---|---|
| I | Blunt injury with minor electrographic abnormalities Blunt or penetrating pericardial wound without cardiac injury, tamponade, or herniation |
| II | Blunt cardiac injury with heart block or ischemic changes without heart failure Penetrating tangential myocardial wound up to, but not extending through, endocardium without tamponade |
| III | Blunt cardiac injury with sustained (≥6 beats/min) or multifocal ventricular contractions Blunt or penetrating injury with septal rupture, pulmonary or tricuspid valvular incompetence, papillary muscle dysfunction, or distal coronary artery occlusion without cardiac failure Blunt pericardial laceration with cardiac herniation Blunt cardiac injury with cardiac failure Penetrating tangential myocardial wound up to, but not extending through, endocardium, with tamponade |
| IV | Blunt or penetrating injury with septal rupture, pulmonary or tricuspid valve incompetence, papillary muscle dysfunction, or distal coronary artery arterial occlusion with cardiac failure Blunt or penetrating injury with aortic or mitral valve incompetence Blunt or penetrating injury of the right ventricle, right atrium, or left atrium |
| V | Blunt or penetrating injury with proximal coronary artery occlusion Blunt or penetrating injury of the left ventricle Stellate wound with <50% tissue loss of the right ventricle, right atrium, or left atrium |
| VI | Blunt avulsion of the heart; penetrating wound producing >50% tissue loss of a chamber |
Introduction
Trauma is overall the fourth most common cause of death and the leading cause of death in individuals younger than 40 years, accounting for 5 million fatalities worldwide on an annual basis. Thoracic trauma is directly responsible for 25% of trauma deaths, and contributes indirectly to another 25% of trauma-related mortalities.
Thoracic trauma may result in a wide spectrum of cardiac lesions, ranging from an asymptomatic myocardial contusion to a rapidly fatal cardiac tamponade or exsanguination caused by a transmural laceration. The reported incidence of cardiac injuries varies widely, with 15% to 76% of patients sustaining major chest injury depending on whether the diagnosis has been made clinically or on autopsy. Nevertheless, in penetrating trauma and in victims who die at the scene of the injury, the incidence of cardiac involvement is much higher.
Cardiac trauma is uncommon in the pediatric population in the United States. Kaptein and colleagues, in a National Trauma Data Bank (NTDB) review, reported that only 0.03% of all pediatric trauma cases (age <8 years) had a documented cardiac injury. The vast majority of cardiac lesions in this population, however, occurred in teenagers (73%). The American Association for the Surgery of Trauma (AAST) has defined the severity of cardiac injuries in their organ injury scale for standardization purposes ( Table 1 ). This article reviews the management of cardiac trauma under the following categories:
- 1.
Blunt cardiac injury (BCI)
- 2.
Penetrating cardiac injury (PCI)
| Grade | Description of Injury |
|---|---|
| I | Blunt injury with minor electrographic abnormalities Blunt or penetrating pericardial wound without cardiac injury, tamponade, or herniation |
| II | Blunt cardiac injury with heart block or ischemic changes without heart failure Penetrating tangential myocardial wound up to, but not extending through, endocardium without tamponade |
| III | Blunt cardiac injury with sustained (≥6 beats/min) or multifocal ventricular contractions Blunt or penetrating injury with septal rupture, pulmonary or tricuspid valvular incompetence, papillary muscle dysfunction, or distal coronary artery occlusion without cardiac failure Blunt pericardial laceration with cardiac herniation Blunt cardiac injury with cardiac failure Penetrating tangential myocardial wound up to, but not extending through, endocardium, with tamponade |
| IV | Blunt or penetrating injury with septal rupture, pulmonary or tricuspid valve incompetence, papillary muscle dysfunction, or distal coronary artery arterial occlusion with cardiac failure Blunt or penetrating injury with aortic or mitral valve incompetence Blunt or penetrating injury of the right ventricle, right atrium, or left atrium |
| V | Blunt or penetrating injury with proximal coronary artery occlusion Blunt or penetrating injury of the left ventricle Stellate wound with <50% tissue loss of the right ventricle, right atrium, or left atrium |
| VI | Blunt avulsion of the heart; penetrating wound producing >50% tissue loss of a chamber |
Blunt cardiac injury
Background
Borch described the very first myocardial contusion in 1676, and Akenside elucidated the first autopsy-verified BCI in 1764. Since the Borch and Akenside reports BCI has been a subject of debate, and the injury is still poorly defined. In the past, BCI has had a variety of diagnostic descriptions including myocardial contusion, cardiac contusion, or commotio cordis, to mention a few. To consolidate the terminology, Mattox and colleagues in 1992 suggested defining nonpenetrating or blunt cardiac lesions in a standardized manner.
In the teenage population, the most common mechanism of traumatic cardiac injury is blunt, accounting for 60% of cases. Kaptein and colleagues, in their NTDB review, noted that rib fractures, hemothorax, and pulmonary contusions served as markers of BCI in pediatric patients, possibly because a pliable chest wall allows transfer of the energy to the heart. Overall, 10% of all teenagers in this study required a resuscitative thoracotomy. The overall mortality in teenagers sustaining cardiac injuries was noted to be 42%.
Sports-related cardiac injuries among young athletes are rare. A recent study in National Collegiate Athletic Association student-athletes reported 273 sudden cardiac deaths over a 5-year study period, with an incidence of 1 per 43,770 participants per year. The majority of deaths (68%) was nonmedical, and occurred outside of the playing field. The medical causes of sudden death were cardiovascular-related incidents in 56% (n = 45), and represented 75% of deaths occurring during exertion. Basketball was by far the highest-risk sport, with an overall annual sudden cardiac death rate of 1 in 11,394 participants per year. Whereas the coronary artery disease as a cause of sudden cardiac death prevails in athletes older than 45 years, electrical conduction abnormalities or cardiac channelopathies have risen in prominence as a cause of cardiac deaths in younger individuals during sports activities.
In general, BCI can be subclassified as electrical or structural in nature, with a clinical presentation ranging from asymptomatic alterations in the electrocardiogram (ECG) or elevation of cardiac enzymes to lesions involving the septal wall, valvular apparatus, coronary artery, or instantly fatal rupture of the cardiac wall. Sinus tachycardia or nonspecific T- and ST-segment changes may be the only manifestation in the vast majority of BCI cases.
The mechanisms of BCI include motor vehicle crashes, auto-versus-pedestrian impacts, crush injuries, falls, assaults, or sports and recreational injuries ( Fig. 1 ). However, in recent decades there have been numerous reports describing instantaneous cardiac arrest following very modest blunt chest injuries either in a domestic setting or during sports-related activities in young individuals without cardiovascular preconditions. It has been postulated that these fatal BCIs are due to a pliable chest wall in young individuals, allowing direct transfer of the impact from the precordium to the myocardium. Another determinant of fatal blunt injury is the timing of the impact during the electrical cardiac cycle. In an experimental model, blunt impact to the anterior chest occurring in a 30- to 15-millisecond window before the T-wave peak produced fatal ventricular fibrillation, which resembled the catastrophic events described in young individuals as commotio cordis ( Fig. 2 ). The incidence of commotio cordis, and its role in sudden cardiac deaths and fatality rates, have been undetermined and underreported. Recently, however, Maron and colleagues investigated the incidence and mortality rates of commotio cordis based on the unique US Commotio Cordis Registry data set. Of a total of 216 cases reported to the registry since 1970, 161 (75%) were younger than 18 years and 77% of victims were engaged in sporting activities during the cardiac event. The overall reported mortality was 72%. Of interest, these investigators noted a progressive 5-fold increase in survival following commotio cordis–related cardiac events, from 10% to 15% before the year 2000 to greater than 50% during the recent 5-year period.
There is no reliable correlation between electrical abnormalities and structural lesions in BCI. The observed structural lesions following BCI range from subendocardial or subepicardial to full-thickness bruising of the myocardium that may result in the spectrum of injuries mentioned in Table 1 . An autopsy study by Parmley and colleagues noted that the most common structural lesion was multichamber cardiac wall rupture, followed by partial lacerations and severe contusions of the myocardium. Valvular lesions in this study were almost nonexistent. In another recent coroner’s study, Teixeira and colleagues from Los Angeles noted that 32% of all deaths following blunt trauma had a BCI, with 64% involving multiple cardiac chambers ( Fig. 3 ). In the contemporary clinical setting, the most common pathologic features following BCI consist of contusions that are asymptomatic and require no workup, unless they are associated with significant dysrhythmias or cardiac failure.
Screening and Diagnosis
There is a lack of a gold standard in the diagnosis of BCI, and there is no single test that can diagnose cellular, electrical, and/or structural lesions. For this reason, the diagnosis of BCI relies on a combination of history, clinical examination, ECG, cardiac enzyme assays, computed tomography (CT) for associated injuries, echocardiography, and nuclear studies. Diagnostic modalities in the workup of BCI and its complications are listed in Box 1 . In many cases, the injury is clinically insignificant and requires observation but no treatment. However, it is of paramount importance to recognize and treat those injuries that are clinically significant and require aggressive management so as to avoid fatal arrhythmias or cardiogenic shock. Many trauma providers define BCI when there is blunt thoracic trauma accompanied by cardiogenic shock, arrhythmias requiring treatment, or structural lesions related to cardiac insult. The recent evidence-based guidelines by the Eastern Association for Surgery on Trauma state that all patients who have a significant mechanism of injury or those who respond poorly to resuscitative efforts should be screened for BCI ( Box 2 ).
History and physical examination
Chest radiograph
Electrocardiogram
Cardiac enzymes
Creatine phosphokinase myocardial band
Cardiac troponin I
Cardiac troponin T
Echocardiography
Transthoracic echocardiography
Transesophageal echocardiography
Nuclear imaging studies
Gated radionuclide angiography
Multiple gated acquisition angiography
Technetium pyrophosphate scanning
Single-photon emission computed tomography
Thallium-201 scanning
Antimyosin scintigraphy
Pulmonary artery catheterization
Level I
An admission electrocardiogram (ECG) should be performed on all patients in whom there is suspected BCI.
Level II
- 1.
If the admission ECG is abnormal (arrhythmia, ST-segment changes, ischemia, heart block, unexplained sinus tachycardia), the patient should be admitted for continuous ECG monitoring for 24 to 48 hours. Conversely, if the admission ECG is normal, the risk of having a BCI that requires treatment is insignificant, and the pursuit of diagnosis should be terminated.
- 2.
If the patient is hemodynamically unstable, an imaging study (echocardiogram) should be obtained. If an optimal transthoracic echocardiogram cannot be performed, the patient should have a transesophageal echocardiogram.
- 3.
Nuclear medicine studies add little when compared with echocardiography, and thus are not useful if an echocardiogram has been performed.
Level III
- 1.
Elderly patients with known cardiac disease, unstable patients, and those with an abnormal admission ECG can be safely operated on provided they are appropriately monitored. Consideration should be given to placement of a pulmonary artery catheter in such cases.
- 2.
The presence of a sternal fracture does not predict the presence of BCI, and thus does not necessarily indicate that monitoring should be performed.
- 3.
Neither creatinine phosphokinase with isoenzyme analysis nor measurement of circulating cardiac troponin T are useful in predicting which patients have or will have complications related to BCI.
Chest Radiography
A chest radiograph is frequently the initial screening modality obtained following blunt chest injury. This investigation is nonspecific for BCI. The most specific pathologic chest-radiographic findings indicating severe BCI are pulmonary congestion and a widened mediastinum owing to cardiac failure or tamponade, respectively. However, a widened mediastinum is more frequently seen with sternal fracture and an associated retrosternal hematoma, thoracic spine fracture with hematoma in the posterior mediastinum, or thoracic aortic injury. Moreover, chest radiography reliably reveals concomitant injuries to the lung and the chest wall.
Electrocardiogram
The 12-lead ECG should be performed in all patients sustaining a significant chest trauma, and they should receive continuous cardiac monitoring. Overall, an abnormal ECG can be noted in 40% to 83% of BCI patients within the first 24 to 48 hours following injury. There is a variety of rhythm abnormalities associated with BCI ( Box 3 ). The most frequently observed electrical abnormalities on ECG are sinus tachycardia, followed by nonspecific ST-T wave changes, atrial fibrillation, premature ventricular contractions, and right bundle branch block. The presence of sinus tachycardia should lead to a search for active hemorrhage. Atrial fibrillation, albeit rare in this setting, has been associated with poor outcomes. The most common fatal arrhythmia following BCI is ventricular fibrillation, even in the absence of major structural abnormality (see Box 3 ).
Sinus tachycardia
Atrial fibrillation
ST-segment elevations/depressions
T-wave abnormalities
Atrioventricular blocks
Right bundle branch block
Bradycardia
Ventricular tachycardia
Ventricular fibrillation
Cardiac Enzymes
Many studies have looked at the diagnostic value of cardiac enzymes, such as myocardial band of creatine phosphokinase (CK-MB), cardiac troponin T (cTnT), or cardiac troponin I (cTnI) in BCI settings. In a prospective study by Salim and colleagues, it was noted that the ECG and cTnI had positive predictive values of 28% and 48% in diagnosing a BCI, respectively. However, with normal ECG and enzyme assay on admission, these markers uncombined had a negative predictive value of 95% and 93%, respectively. When both tests (ECG + cTnI) were abnormal or normal, the positive and negative predictive values increased to 62% and 100%, respectively. Another study by Walsh and colleagues noted that combination of ECG and cardiac cTnI reliably diagnosed significant BCI. Likewise, Rajan and Zellweger observed that a cTnI value of less than 1.05 μg/L on admission and within 6 hours ruled out BCI. However, there are no studies that correlate cardiac biomarkers to the extent of BCI or outcomes. Some trauma care providers do not perform routine troponin assays unless evaluating for coronary artery involvement following BCI. Accepting the ambiguity of the currently available data, the authors’ current practice is to obtain a 12-lead ECG and cTnI assays on admission, at 4 hours, and at 8 hours in all patients sustaining significant BCI.
Echocardiography
Echocardiography is not a useful screening tool following BCI, and should be reserved for patients with hemodynamic compromise or arrhythmias. Echocardiography provides direct visualization of ventricular contusions, cardiac chamber size, wall motion, valvular function, cardiac tamponade, septal defects, and/or intracardiac thrombi. In many instances, transthoracic echocardiography (TTE) may be limited by chest wall injuries, pain, chest tubes, and chest-wall emphysema following severe chest trauma.
Karalis and colleagues performed a TTE on 105 patients following severe thoracic injury. Twenty patients (19%) required a transesophageal echocardiogram (TEE) owing to suboptimal TTE images. These investigators reported myocardial contusion in 30% of patients, infrequently requiring interventions and associated with favorable outcome. TEE was found to be of value when TTE images were suboptimal and in cases of suspected aortic injury. Bromberg and colleagues demonstrated the role of TTE in children with hemodynamic compromise in the setting of BCI. Based on these reports, TTE may be a good choice as the initial study, with TEE being of use in cases with suboptimal TTE images or suspected aortic injury.
Treatment
Asymptomatic patients with abnormal ECG or cardiac enzymes should be observed in a monitored intensive care unit until findings return to normal. There is no need for any specific treatment in this group of patients. Echocardiography should be performed to evaluate for any underlying functional or anatomic abnormalities. The treatment of symptomatic patients with cardiogenic shock or arrhythmias is similar to that for nontraumatic conditions, and may include replacement of intravascular volume, inotropic agents, and occasional placement of an intra-aortic balloon pump. Serial echocardiography should be performed to rule out delayed tamponade or other structural complications. Treatment of coronary artery injury includes medical management, percutaneous intervention, and/or operative revascularization. Fibrinolytic therapy is usually contraindicated because of associated injuries, although it may be an option in isolated cardiac trauma. Treatment of any BCI with pericardial tamponade and hypotension requires immediate surgical exploration. Operative repair is preferably performed off bypass, to avoid the risks associated with systemic anticoagulation and the risks of inducing arrest in a severely contused heart.
Cardiac ruptures following severe blunt impact are universally fatal. Multiple coroner’s studies have revealed that approximately 30% of all deaths following blunt trauma are due to cardiac rupture. Large myocardial contusions following BCI are associated with arrhythmias, late rupture, aneurysm formation, congestive heart failure, and/or intracavitary thrombus formation, and hence require careful clinical and sonographic follow-up. Asymptomatic patients with an absence of BCI structural abnormalities have a good prognosis.
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Trauma is the leading cause of death in individuals younger than 40 years
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Cardiac trauma in the pediatric population is rare
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Blunt trauma is the most common mechanism in the teenage population
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Commotio cordis refers to a rare catastrophic event caused by ventricular fibrillation as a result of a BCI
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Most common abnormality following a BCI is asymptomatic myocardial contusion
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Diagnosis is established with a combination of history, physical examination, ECG, cardiac enzymes, echocardiography, and/or CT for associated injuries
- •
Clinical presentation includes a wide spectrum ranging from asymptomatic to catastrophic events
- •
Based on the clinical presentation, treatment may involve observation only or management of cardiogenic shock, arrhythmias, and/or coronary injuries
- •
Careful clinical and sonographic follow-up is recommended
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