Initial evaluation and management of blunt cardiac injury

INTRODUCTION — Blunt cardiac injury (BCI) encompasses a spectrum of pathology ranging from clinically silent, transient dysrhythmias to deadly cardiac wall rupture. The most common form is "cardiac contusion" (ie, injury to the myocardium), which remains the subject of considerable debate. The absence of a clear definition and accepted gold standard for testing makes the diagnosis of cardiac contusion difficult. Important considerations in blunt cardiac trauma include dysrhythmia, cardiac wall motion abnormalities, possibly progressing to cardiogenic shock, and rupture of valves, the septum, or a ventricular, atrial, or septal wall [1,2].

The evaluation and management of cardiac injuries sustained in adults from blunt thoracic trauma will be reviewed here. Other injuries from blunt trauma and injuries in children are discussed separately.

●(See "Initial evaluation and management of blunt thoracic trauma in adults".)

●(See "Thoracic trauma in children: Initial stabilization and evaluation".)

●(See "Commotio cordis".)

EPIDEMIOLOGY, DEFINITIONS, AND SCORING — The incidence of blunt cardiac injury (BCI) is unknown, and estimates vary widely. Of diagnosed BCIs, "myocardial contusion" or "cardiac contusion" is most common. However, each of these terms has been used to refer to a range of cardiac injuries. The absence of clear diagnostic criteria and reliable diagnostic tests makes reporting difficult. Suggestive symptoms may be unrelated to BCI, while some injuries may be clinically asymptomatic. Furthermore, some criteria used to define significant BCI, such as dysrhythmias, may be due to the effects of multiple trauma in a susceptible patient (eg, patient with preexisting heart disease). Other diagnostic criteria, such as an elevated troponin, may be seen in major trauma remote from the chest [3]. (See 'Cardiac biomarkers' below.)

Due to the ambiguity surrounding the terms "myocardial contusion" and "cardiac contusion," we prefer to describe BCIs in terms of specific injuries (eg, septal rupture, myocardial infarction) or cardiac dysfunction (eg, diminished contractility in the absence of dysrhythmia or hemorrhage). (See 'Types of injury' below.)

Cardiac rupture is the most devastating BCI. Most patients who sustain rupture of a heart chamber do not reach the emergency department alive. Chamber rupture is described primarily in autopsy series [4,5]. (See 'Anatomy and mechanism of injury' below.)

While not widely used in emergency medicine, the cardiac injury scale developed by the American Association for Surgery of Trauma is easy to use, applies to both blunt and penetrating cardiac injuries, and provides a standard scheme for research purposes and documentation (table 1) [6].

ANATOMY AND MECHANISM OF INJURY — Blunt cardiac injury (BCI) occurs most often from motor vehicle collisions (MVCs) [7]. Falls and crush injuries cause a smaller number. Commotio cordis, a rare type of BCI in which low impact chest trauma causes sudden cardiac arrest, usually occurs from being struck by a projectile during sports. Arrest appears to stem from the timing of the blow during a period of electrical susceptibility.

Rapid deceleration is the mechanism responsible for most BCIs. A direct blow to the precordium also accounts for a sizable number of cases. Any patient involved in a MVC with sudden deceleration, or who sustains significant chest trauma or severe multiple trauma is at risk.

Several forces may be involved in BCI, including compression of the heart between the spine and sternum, abrupt pressure fluctuations in the chest and abdomen, shearing from rapid deceleration, and blast injury (figure 1 and figure 2) [2,8,9]. In addition, fragments from rib fractures can directly traumatize the heart.

The right heart is most commonly injured. This is probably due to its position closest to the anterior chest wall (figure 3 and figure 4). High pressure ventricular injuries appear to be as common as low pressure atrial injuries, but findings vary based on the type of study (ie, clinical or autopsy). In autopsy series, ventricular injuries predominate. Other pathological findings include valvular tear or rupture, septal tears, and coronary artery thrombosis or laceration, but these are less common [8].

PREHOSPITAL MANAGEMENT — Prehospital management depends upon patient symptoms and severity of illness. Prehospital providers should treat patients with possible severe cardiac injury according to the principles of Advanced Trauma Life Support, paying special attention to the patient's airway, breathing, and circulation. Rapid transport to the closest trauma center is crucial; interventions causing unnecessary delay must be avoided.

Diagnosis of blunt cardiac injury (BCI) in the field can be difficult. Trauma patients may have multiple injuries and signs suggestive of BCI, such as dysrhythmia, which may stem from hypotension, acidosis, or preexisting heart disease. For patients with minor injuries and no respiratory difficulty, chest pain, or other concerning symptoms, no intervention may be needed.

CLINICAL FEATURES

Overview — The clinical features of blunt cardiac injury (BCI) can vary widely [1]. Concomitant injuries often affect presentation, and it may be difficult to determine whether symptoms stem primarily from the cardiac injury. Mortality from major structural injuries, such as chamber rupture or perforation, is high and most such patients die in the field. The basic types of BCI are described below; diagnostic approach and management are addressed below. (See 'Our approach' below and 'Management' below.)

Types of injury

●Myocardial rupture – Nonspecific signs and concomitant distracting injuries make clinical diagnosis of myocardial rupture difficult [7]. Signs such as hypotension associated with distended neck veins and muffled heart sounds suggest pericardial tamponade (ie, contained myocardial tear or rupture), which may occur with BCI. However, such signs may not be present (eg, patient with hemorrhage and hypotension may not have distended neck veins). Immediate bedside ultrasound may reveal the diagnosis. (See 'Echocardiogram' below.)

Most patients with severe BCI, such as uncontained myocardial rupture, do not reach the emergency department (ED) alive [10,11]. Of those who do, hypotension may reduce pressure on the injured myocardium, which may then worsen as fluid resuscitation restores blood pressure. In a minority of patients, rapid diagnosis by echocardiography or CT scan and operative intervention can be lifesaving [12]. Less severe injuries to the ventricular wall may lead to delayed necrosis and manifest as delayed rupture within several days of admission.

Atrial rupture occurs far less often than ventricular rupture (most likely due to the location of the atria and their lower compliance) and presentation may be delayed and less acute [13]. Right atrial rupture is seen in about 10 percent of wall ruptures from blunt trauma, and left atrial rupture less often.

●Septal and valvular injury – Septal injury appears to be rare and its presentation variable. Septal injury may involve insignificant tears or frank rupture, and may occur in isolation or with valvular injury. Findings may include acute valvular insufficiency with widened pulse pressure and signs of acute heart failure.

Isolated valvular injury is likewise rare [9,14,15]. The aortic valve is most often injured, followed by the mitral and tricuspid valves. The lesion may consist of a tear of the leaflet or a partial or full thickness tear of the papillary muscle or chordae tendineae. Presentation may vary, in part depending upon the lesion, but falls somewhere on the spectrum of acute valvular insufficiency with right or left sided heart failure and a new cardiac murmur. A widened pulse pressure may be present with aortic valvular injury. Treatment for septal and valvular injury is generally surgical and timing depends upon the presenting signs and acuity [16,17].

One retrospective review found a significant increase in tricuspid and aortic valve insufficiency, incompetence, and regurgitation among patients with a history of BCI. Milder cases may go undiagnosed initially and present late with heart failure from long-standing valvular dysfunction [18]. While less common, mitral valve insufficiency has also been reported [15,19].

●Myocardial infarction – Myocardial infarction (MI) is a rare complication of BCI reported in victims of motor vehicle collisions and minor trauma. Causes include coronary artery dissection, laceration, and thrombosis [20-28]. The left anterior descending artery appears to be involved most often [29]. (See 'Electrocardiogram' below.)

●Cardiac dysfunction – The lack of a clear definition for myocardial contusion is problematic, and we prefer the term cardiac dysfunction. (See 'Epidemiology, definitions, and scoring' above.)

The exact incidence of BCI with cardiac dysfunction (eg, decreased contractility) is unknown. The cause of such dysfunction can be difficult to determine in the multiply injured patient with many reasons for hypotension. An echocardiogram is useful in trauma patients with signs of cardiac dysfunction to diagnose the cause and assist with management. (See 'Echocardiogram' below.)

In animal studies, cardiac dysfunction from blunt trauma often manifests multiple hemodynamic derangements unrelated to dysrhythmia [30,31]. Potential derangements include diminished contractility, decreased cardiac and stroke volume indices, and low mean arterial pressure. Myocardial metabolism may be impaired, as reflected by decreases in oxygen consumption and lactate extraction, and right-sided cardiac pressures may increase. Many of these changes resolve in less than a day.

●Dysrhythmia – Clinicians should assume that hemorrhage is the cause of tachycardia in the trauma patient until proven otherwise. Once hemorrhage is ruled out, findings such as unexplained, persistent tachycardia, new bundle branch block, and minor dysrhythmia (eg, occasional premature ventricular contractions) raise concern for BCI. Patients with any of these findings should be admitted for cardiac monitoring. Case reports describe a wide range of dysrhythmias associated with BCI, including supraventricular tachycardia (eg, atrial fibrillation) and ventricular fibrillation [32,33]. (See 'Management' below.)

Few patients with BCI develop a dysrhythmia that requires treatment. While diagnostic criteria vary, making the number difficult to determine, the range often cited is 0 to 5 percent among patients with BCI [34-36]. Criteria may involve elevated cardiac biomarkers, an abnormal ECG or echocardiogram, or some combination of these. Most patients admitted for monitoring manifest minor dysrhythmias.

Commotio cordis, a type of BCI, is among the most common causes of sudden death during athletic participation. A direct blow to the chest during a sensitive time of the cardiac cycle causes ventricular fibrillation and sudden collapse seconds after impact. Commotio cordis is discussed separately. (See "Commotio cordis".)

●Concomitant injury and sternal fracture – BCI often presents with concomitant injuries. These can include injuries to the head, thorax, abdomen, or spine [7,8]. According to an eight-year review of the United States National Trauma Data Bank involving over 15,000 patients with BCI, the finding most strongly associated with BCI was hemopericardium (odds ratio [OR] 9.58), which was almost twice as likely as either sternal fracture or thoracic aortic injury [37]. Nevertheless, sternal fractures have been associated with BCI in a number of observational studies. In one autopsy series of patients who died following a fall from a height, sternal fractures were found in 76 percent of cases involving cardiac injury, whereas only 18 percent of cases had a sternal fracture without associated cardiac injury [5]. A review of a German trauma database reported a substantial risk of BCI among patients with sternal fracture but used a liberal definition of BCI, which may have inflated the number of injuries [38].

Despite these reports, a sternal fracture does not necessarily imply the presence of BCI, particularly if the fracture is visible only on CT, and several series report that BCI seldom occurs in cases of isolated sternal fracture [39-44]. As an example, a large retrospective study looked at patients with chest trauma who were evaluated with both plain chest radiographs and chest CT scans [45]. Of the 292 patients with sternal fractures (2 percent of the total study population), 94 percent sustained injuries seen only on CT, seven were diagnosed with a cardiac contusion, and only one required a surgical procedure related to the sternal injury. The presence of a sternal fracture was not associated with increased mortality. Another retrospective review of 235 patients treated for a sternal fracture at a single institution reported no correlation between the depth or displacement of a sternal fracture and the likelihood of BCI [46]. The evaluation and management of sternal fractures is discussed separately. (See "Initial evaluation and management of chest wall trauma in adults", section on 'Sternal fractures'.)

INITIAL STABILIZATION — While blunt cardiac injury (BCI) is often associated with thoracic trauma, it can occur in any patient with multisystem trauma. Initial evaluation proceeds according to standard Advanced Trauma Life Support protocols, beginning with stabilization of the patient's airway, breathing, and circulation. (See "Initial management of trauma in adults".)

Clinicians should assume that hypotension in the trauma patient stems from hemorrhage, not cardiac dysfunction, until proven otherwise. With hypotension in the setting of isolated chest trauma, clinicians should look for pericardial tamponade or a tension pneumothorax in addition to hemorrhage. Evaluation and initial management of the patient with thoracic trauma is discussed separately. (See "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of penetrating thoracic trauma in adults" and "Emergency ultrasound in adults with abdominal and thoracic trauma".)

EVALUATION AND DIAGNOSIS OF ADULT WITH BLUNT CHEST TRAUMA

Our approach — The role of the emergency clinician is to rapidly identify and initiate management for any surgically correctable lesion or life-threatening condition and to identify those patients at risk for blunt cardiac injury (BCI) and initiate appropriate consultation and testing. In an adult patient with blunt chest trauma, our approach is the following:

●We perform a standard bedside ultrasound examination (ie, focused assessment with sonography for trauma [FAST]). The FAST is an excellent screening test for clinically significant hemopericardium, which suggests ventricular wall rupture (movie 1) [4,47,48]. (See "Emergency ultrasound in adults with abdominal and thoracic trauma" and 'Valve, septum, or ventricular wall injury' below.)

An algorithm for the evaluation of a hemodynamically stable adult with suspected BCI and a FAST without hemopericardium is provided (algorithm 1).

●We obtain a screening electrocardiogram (ECG) in a patient with any of the following (see 'Electrocardiogram' below):

•Evidence of significant anterior chest wall trauma (eg, sternal fracture, manubrium fracture, retrosternal hematoma)

•Major mechanism of injury (eg, rollover, high speed, fatality at scene) in an older adult or a patient with known coronary artery disease

•Circumstances of trauma suggestive of heart disease (eg, accident preceded by syncope or shortness of breath)

•Active signs or symptoms consistent with heart disease, including chest pain suggestive of acute coronary syndrome (eg, pressure, heaviness, tightness, fullness, squeezing, radiation to one or both shoulders)

•Signs of heart failure (eg, pulmonary edema, distended jugular veins)

•Abnormal heart sounds (eg, muffled sounds, holosystolic or diastolic murmur)

•Unexplained tachycardia, bradycardia, or hypotension

•New dysrhythmia

●In a patient with a FAST that is nondiagnostic for hemopericardium, and unexplained, persistent shock out of proportion to apparent injuries or despite aggressive resuscitation, signs of heart failure, or abnormal heart sounds (eg, muffled sounds, holosystolic or diastolic murmur), we obtain bedside echocardiography. A formal echocardiogram will better identify wall motion abnormalities and valvular disorders compared with FAST. Clinicians must remember that hemorrhage remains the primary cause of traumatic shock and consider other common noncardiac causes of shock (eg, tension pneumothorax). (See 'Echocardiogram' below.)

●In a patient with unexplained tachycardia that persists over several hours despite adequate fluid resuscitation and pain control, a new conduction block (eg, bundle branch block), or a significant new dysrhythmia (except for mild sinus tachycardia), we admit for cardiac monitoring, serial cardiac biomarkers, cardiology consultation, and likely echocardiography. If no prior ECG is available for comparison, a conduction block that is uncommon for the patient's age or comorbidities should be considered new. (See 'Echocardiogram' below and 'Dysrhythmia' below and 'Cardiac biomarkers' below.)

●In the rare patient with blunt chest trauma and evidence of myocardial infarction on ECG, we obtain cardiac biomarkers and immediately consult both cardiology and cardiac surgery. (See 'Acute coronary syndrome' below.)

●We obtain serial cardiac biomarkers in a patient with ECG abnormalities, symptoms/comorbidities suggestive of acute coronary syndrome, abnormal heart sounds, or signs of hemodynamic instability or heart failure. Otherwise, we do not routinely obtain a troponin in stable patients. Controversy continues regarding the role of biomarkers for the evaluation of BCI, and some experts will routinely obtain a troponin in all patients having an ECG or in those with evidence of significant anterior chest wall trauma (eg, sternal fracture). (See 'Cardiac biomarkers' below.)

●In other patients for whom concern persists but do not have findings consistent with severe BCI (eg, shock, heart failure, abnormal heart sounds, FAST with hemopericardium), we observe in the emergency department (ED) for four to six hours for cardiac monitoring and serial examinations/ECGs. A minimum of two ECGs, obtained toward the beginning and end of the observation period, should be performed. (See 'Electrocardiogram' below and 'Cardiac biomarkers' below.)

Diagnostic tests

Electrocardiogram — The ECG is an important screening test for hemodynamically stable patients with potential BCI. An ECG consistent with BCI may reveal persistent sinus tachycardia, another dysrhythmia, a new bundle branch block, or ST depressions or elevations [49,50]. It can be difficult to determine whether the abnormality is a primary event (eg, an acute coronary syndrome that preceded trauma), a direct result of cardiac injury, or a problem brought on by the physiologic stress of severe trauma.

A meta-analysis (28 studies, 1587 patients) found that the initial ECG had low sensitivity (55 percent, 95% CI 45-65 percent) but good specificity (85 percent, 95% CI 75-91 percent) for detecting BCI [51]. The study defined BCI as injury observed on echocardiogram, magnetic resonance imaging (MRI), a radionucleotide scan, or autopsy or based on clinical criteria such as pericardial hemorrhage, coronary artery thrombosis, congestive heart failure, or serious dysrhythmia (non-specific ST changes were not included).

A large, retrospective study found that patients diagnosed with BCI have two to four times the baseline risk of dysrhythmia, depending upon the patient's age, compared with matched controls who sustain blunt thoracic trauma without BCI [52]. Although the study has significant methodologic limitations, it notes the incidence of dysrhythmia other than sinus tachycardia (ST) to be <1 percent, and the most common dysrhythmia other than ST to be atrial fibrillation. ECG abnormalities, such as ST changes and bundle branch blocks, are not discussed.

Echocardiogram — Echocardiography can provide important information in the patient who manifests signs consistent with significant BCI, but contributes little to the management of hemodynamically stable patients without dysrhythmia [8,53-55]. We obtain an echocardiogram in any patient with blunt thoracic trauma and unexplained, persistent shock out of proportion to apparent injuries or despite aggressive resuscitation, and in any patient with signs consistent with significant BCI (eg, dysrhythmia, new bundle branch block, ECG with ischemic changes, signs of heart failure, abnormal heart sounds).

Focused assessment with sonography for trauma (FAST) provides the preferred initial approach for sonographic evaluation. It enables trained clinicians to determine the presence of pericardial effusion and pneumothorax rapidly and accurately. (See "Emergency ultrasound in adults with abdominal and thoracic trauma", section on 'Pericardial and limited cardiac examination'.)

Once pericardial tamponade is ruled out, an echocardiogram is useful in trauma patients with signs of cardiac dysfunction to diagnose the cause of dysfunction, estimate the need for volume resuscitation or inotropic support, and identify other injuries requiring intervention [2,8,56]. Signs suggestive of injury include abnormal cardiac wall motion and decreased cardiac contractility. Such findings may predate the current trauma in patients with chronic heart disease. Nevertheless, any abnormality should be investigated with a formal comprehensive echocardiogram performed by skilled clinicians to define wall motion abnormalities, identify thrombus, and to identify valvular rupture or dysfunction [57].

While transthoracic echocardiogram (TTE) is the initial study performed for many patients with suspected blunt cardiac trauma, ECG abnormalities, and elevated troponin or hemodynamic instability, a transesophageal echocardiogram (TEE) is superior for investigating the cause of persistent hemodynamic instability or other problems thought to be related to BCI [58]. TEE may be needed when TTE provides a suboptimal view or there is concern for additional injuries. TEE provides a clear view of wall motion abnormalities and valvular and septal injuries. While its benefits are tempered by increased invasiveness, TEE improves sensitivity for injuries that require intervention. However, TEE is contraindicated in a patient with suspected or diagnosed esophageal injury.

A meta-analysis (20 studies, 1510 patients) found that TTE had a low sensitivity (47 percent, 95% CI 34-60 percent) but good specificity (91 percent, 95% CI 84-96 percent) for detecting BCI [51]. In the same meta-analysis (3 studies, 309 patients), the sensitivity of TEE was much better (87 percent, 95% CI 40-99 percent) but had a slightly worse specificity (72 percent, 95% CI 36-98 percent). In a study where patients with "severe chest injuries" underwent both TEE and TTE, TEE provided optimal images in approximately 98 percent of patients compared with 60 percent for TTE [59]. Moreover, multiple serious injuries including wall and valvular ruptures were not visible on TTE.

Cardiac biomarkers — We obtain cardiac biomarkers in a patient with ECG abnormalities, symptoms/comorbidities suggestive of acute coronary syndrome, abnormal heart sounds (eg, muffled sounds, holosystolic or diastolic murmur), or signs of hemodynamic instability or heart failure. Some authors obtain cardiac biomarkers in a patient with evidence of significant anterior chest wall trauma (eg, sternal fracture, manubrium fracture, retrosternal hematoma), which is discussed below. Concerning ECG abnormalities include any new dysrhythmia (other than mild sinus tachycardia), new conduction blocks, and ST or T wave abnormalities suggestive of ischemia.

When cardiac biomarkers are indicated, we typically obtain troponin at presentation and four to six hours thereafter. Some experts and trauma centers will obtain high-sensitivity troponins at a shorter interval, but evidence is limited to support a routine threshold or interval [60,61]. (See "Troponin testing: Analytical considerations".)

Otherwise, we do not routinely obtain cardiac biomarkers since the utility of cardiac biomarkers in the setting of BCI remains unclear [62,63]. There are several reasons, including the lack of a gold standard for BCI, highly variable clinical outcomes, and the use of different biomarkers. A meta-analysis (17 studies, 1491 patients) found that a negative initial troponin I had a low sensitivity (64 percent, 95% CI 52-75 percent) but good specificity (84 percent, 95% CI 72-91 percent) for detecting BCI [51]. The sensitivity increased to 88 percent when a negative troponin I was combined with a normal ECG. Thus, some experts recommend routinely obtaining an initial and second (four to six hours after injury) troponin to exclude BCI.

●Patient with abnormal ECG or hemodynamic instability – In the rare case of the blunt thoracic trauma patient with evidence of myocardial infarction on ECG, serial biomarkers should be measured and immediate consultation with both cardiology and cardiac surgery obtained. However, the use of cardiac biomarkers may not affect the management of blunt trauma patients with hemodynamic instability or an abnormal ECG that does not demonstrate myocardial infarction. Such patients generally undergo echocardiography and are admitted for further evaluation.

In a patient with clinical or ECG findings consistent with BCI, an elevated troponin may be associated with increased morbidity and mortality, but the precise threshold is unclear [64]. In one study of 187 patients with blunt chest trauma, an increased troponin at admission or within six hours of arrival correlated with increasing risk of dysrhythmia and decreased ejection fraction [65].

In another study, no adverse outcomes occurred in a subgroup of 16 patients with initial ECG abnormality but no elevation in troponin at four to six hours [62]. According to one review of 10 prospective studies involving 1609 patients admitted to the hospital following blunt chest trauma, a normal troponin using a lower reference limit was associated with a high negative predictive value for clinically significant cardiac complications [66]. Of note, the complications, reference levels, and diagnostic criteria were heterogeneous among the included studies. While all these studies are limited, they suggest that troponin measurements may be useful in the patient with ECG abnormalities. However, with a markedly abnormal ECG or complex dysrhythmia, it is doubtful a negative troponin provides reassurance that further complications will not occur, and such patients should be admitted for further evaluation [8,62,67].

●Patient with normal ECG and without evidence of significant anterior chest wall trauma – In the absence of hemodynamic instability, evidence of significant anterior chest wall trauma, or an abnormal ECG, several observational studies suggest that an elevated cardiac troponin is nonspecific for the presence of a clinically significant BCI and has little prognostic value [62,65,68,69]. While a meta-analysis of 28 studies involving 7242 patients showed higher biomarker elevations in those diagnosed with myocardial contusion, there was significant variability among biomarkers, with sensitivities as low as 38 percent and specificities up to 85 percent [70]. Moreover, abnormally elevated troponins occur more frequently among patients with significant nonthoracic trauma [3]. This latter finding may stem from catecholamine-induced stress, hypovolemic shock with reperfusion injury, oxidative injury, bacterial or viral toxins, or microcirculatory dysfunction.

Instead of biomarkers, we use repeat examinations, serial ECGs, and cardiac monitoring during a brief course of observation (four to six hours) to screen for BCI, if concern exists. The use of biomarkers has not been shown to be more accurate than this approach [62,69]. While some studies suggest that biomarkers are sensitive indicators of BCI, whether such injuries are significant in patients without clinical signs or symptoms remains unclear [71].

●Patient with normal ECG and vital signs, evidence of significant anterior chest wall trauma, and chest pain – Some contributors will obtain serial cardiac markers and ECGs and discharge if these remain normal. Other contributors will obtain serial ECGs and only obtain cardiac biomarkers if worrisome clinical signs develop (eg, unexplained tachycardia or hypotension). Evidence does not exist that measuring troponins in this population will impact patient-important outcomes.

Role of cross-sectional imaging — Several observational studies suggest that imaging with CT or MRI can identify areas of contusion on the myocardium in patients suspected of BCI. However, it remains unclear how such findings can inform clinical care, and the use of such imaging should be considered investigational pending further study [72-74].

Nevertheless, as CT is often obtained in patients with multitrauma, the radiologist may see obvious signs of cardiac injury (eg, wall rupture, valve damage, hemopericardium) or may report findings suggestive of such injury. Suggestive findings may include direct signs (eg, decreased attenuation of the myocardium) or indirect signs (eg, pulmonary edema and ventricular enlargement due to ischemia) [75]. In cases of pericardial rupture, pneumopericardium can be seen on CT as gas outlining the heart. Other findings suggestive of pericardial injury include contour irregularities, dimpling, and discontinuity of the pericardium. Chamber enlargement may be an indirect sign of valvular injury.

The American College of Radiology (ACR) Appropriateness Criteria for Blunt Chest Trauma-Suspected Cardiac Injury list chest CT or CT angiography (CTA) with or with and without intravenous (IV) contrast as a usually appropriate study for the stable patient with suspicion of injury because the excellent spatial resolution and three-dimensional reconstructions can reveal anatomic disruptions and cardiovascular pathology [58]. CTA may be beneficial if other vascular structures are considered at risk or for pre-surgical planning. Magnetic resonance imaging (MRI), single-photon emission CT (SPECT), and positron-emission tomography (PET) scanning are considered "usually not appropriate" either due to lack of literature or lack of perceived marginal benefit over a faster and more easily obtained CT study or echocardiogram.

MANAGEMENT — Patient presentation and clinical findings determine management.

Myocardial or cardiac contusion — The absence of a clear definition and accepted gold standard for testing makes the diagnosis of "myocardial contusion" or "cardiac contusion" difficult. Due to the ambiguity surrounding these traditional terms, we and many trauma researchers prefer to describe blunt cardiac injuries (BCIs) in terms of specific pathology (eg, septal rupture, myocardial infarction) or cardiac dysfunction (eg, diminished contractility in the absence of dysrhythmia or hemorrhage) [1,76-78]. This approach avoids ambiguity and allows clinicians to manage patients based upon discrete problems identified through clinical evaluation and diagnostic testing. Such management is described below.

Valve, septum, or ventricular wall injury — Patients with clinical or echocardiographic evidence of severe cardiac injury (eg, ruptured valve, septum, or ventricular wall; cardiac tamponade) require emergency surgical consultation.

Induction agents with cardiodepressive effects and positive pressure ventilation following intubation may further compromise cardiac function in patients with these injuries. If possible (ie, patient is not in acute respiratory distress and is able to protect their airway), it may be helpful to delay intubation until the patient is in the operating room [47].

If tamponade is suspected either clinically (eg, hypotension, distended jugular veins, muffled heart sounds) or identified by ultrasound, pericardiocentesis is performed. Tamponade that results from an atrial tear may be amenable to pericardiocentesis with periodic drainage using a pigtail catheter until definitive surgical repair can be performed.

Among unstable patients who may not survive transfer to an operating room, emergency department (ED) thoracotomy, rather than pericardiocentesis, may be the best treatment for cardiac tamponade [4,79]. Pericardiocentesis can be an effective temporizing measure, and may be attempted. Nevertheless, in the setting of blunt trauma, ED thoracotomy rarely results in successful resuscitation. ED thoracotomy is discussed elsewhere. (See "Emergency pericardiocentesis" and "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Role of emergency department thoracotomy'.)

If cardiac injury is suspected in a hypotensive patient and rapid bedside ultrasound is unavailable to exclude tamponade or valvular injury, the cardiac surgery and cardiology services should be consulted immediately. Such patients should be admitted to a surgical service with cardiology consultation unless operative management is clearly unnecessary.

Acute coronary syndrome — The management of myocardial infarction (MI) in the setting of BCI is controversial due to the rarity of the disease and the frequent presence of multiple injuries. Catheterization with stenting may be the best approach, although some advocate bypass surgery [20,80,81]. Thrombolytics are best avoided, unless both bypass surgery and angiography are unavailable. Although there are reports of successful treatment with thrombolytics, severe bleeding complications may occur [81-83]. Management should be determined in consultation with cardiology. Cardiac surgery consultation is needed in the rare event that a coronary artery laceration or dissection is identified.

For patients with features suggestive of BCI and in whom cardiac biomarkers are found to be elevated, cardiology consultation is obtained, and the patient is admitted for cardiac monitoring and further evaluation.

A screening echocardiogram and cardiac biomarkers do NOT appear to add to the management of the hemodynamically stable patient without historical or clinical features suggestive of significant BCI, and we do not routinely obtain these tests [54]. (See 'Diagnostic tests' above.)

Cardiac dysfunction — Echocardiography is warranted in patients with BCI for any clinical findings suggestive of hypotension or acute heart failure [43]. Identified injuries are managed appropriately; patients without identifiable injury but with persistent dysfunction (eg, episodes of hypotension) are admitted for cardiac monitoring. Floor telemetry is appropriate for the patient with minor abnormalities, no significant concomitant injuries, and normal hemodynamics. All other patients should have a higher level of monitoring (eg, cardiac intensive care unit). Cardiology consultation is needed for any patient with hemodynamic instability in whom cardiac injury cannot be excluded.

Dysrhythmia — We advocate management using standard Advanced Cardiovascular Life Support (ACLS) protocols when necessary, although no studies have looked specifically at treatment of BCI-related dysrhythmia. (See "Adult basic life support (BLS) for health care providers", section on 'Resuscitation guidelines' and "Pediatric basic life support (BLS) for health care providers", section on 'Basic life support approach'.)

In patients with a new dysrhythmia (eg, high grade conduction blocks, new onset atrial fibrillation, supraventricular or ventricular tachycardia) following BCI, it is appropriate to perform a bedside echocardiogram to look for wall motion abnormalities or injuries that require emergency surgery [43,84]. (See 'Echocardiogram' above.)

Clinicians should assume that hemorrhage is the cause of tachycardia in the trauma patient until proven otherwise. Once hemorrhage is ruled out, findings such as unexplained tachycardia that persists over several hours despite adequate fluid resuscitation and pain control, new bundle branch block, or dysrhythmia raise concern for BCI. Patients with such findings are admitted for cardiac monitoring and likely echocardiography.

Cardiology consultation is needed for any patient with a new dysrhythmia (including persistent tachycardia), signs of heart failure, or hemodynamic instability likely due to cardiac dysfunction.

Floor telemetry is appropriate for the patient with minor abnormalities (eg, intermittent premature ventricular or atrial contractions), no significant concomitant injuries, and normal hemodynamics [43,85,86]. All other patients should have a higher level of monitoring. Established criteria for monitoring do not exist, but 24 to 48 hours of monitoring is reasonable for minor abnormalities. Rarely do abnormalities first present after 24 hours. If dysrhythmias persist during monitoring, cardiology consultation should be obtained.

PEDIATRIC CONSIDERATIONS

Epidemiology — Reports of blunt cardiac injury (BCI) in children are uncommon, and thus it is difficult to know the precise incidence or to determine if these injuries occur by different mechanisms than in adults. BCI occurs in less than 5 percent of children with blunt thoracic trauma [87-89]. Myocardial contusions may account for as much as 60 percent of these injuries [90]. However, as with adults, there is no clear definition of "myocardial contusion" in children and no accepted gold standard for testing, which makes diagnosis difficult. "Cardiac dysfunction" is now used at the author's institution for any child with decreased contractility.

Motor vehicle collisions (MVC) are routinely cited as the most common cause of BCI in both children and adults [7,89,91-93]. In a systematic review, MVCs accounted for 53 percent of all BCIs in children [90]. Other, less common cardiac injuries sustained by children are ventricular septal defects and papillary muscle rupture [89]. According to a retrospective review, the thoracic and non-thoracic injuries most often associated with BCI in children include pulmonary contusion, rib or clavicle fractures, brain injury, and abdominal injuries [89].

Clinical features — It is difficult to determine if children are more susceptible to BCI than adults. However, the chest wall of a child is more compliant than the adult, and therefore during blunt thoracic trauma more kinetic energy can be transmitted to a child's intrathoracic structures without causing bony injury. Thus, BCI in children may go undiagnosed because external examination and bony radiographic findings do not reflect the strength of the forces involved. Most BCIs in such cases are cardiac dysfunction that resolve on their own without any sequela, while most patients with a clinically significant BCI have some abnormal finding on chest examination, chest radiograph, or ECG. (See "Thoracic trauma in children: Initial stabilization and evaluation", section on 'Anatomy'.)

Commotio cordis is a type of BCI that occurs with greater frequency in child athletes, most often as the result of a projectile (eg, baseball, hockey puck) striking the chest during a sensitive time during the cardiac cycle. Commotio cordis often results in ventricular fibrillation and sudden cardiac death. (See "Commotio cordis".)

Unlike adults, children with BCI often have few presenting signs or symptoms so diagnosis may be more difficult [49,93,94]. The presence of any of the following features in the setting of blunt trauma raises the possibility of clinically significant BCI:

●A dysrhythmia or heart failure

●Ecchymosis, abrasions, or deformity of the chest wall

●Focal tenderness over superior ribs, sternum, or scapula

●Muffled heart tones or a new murmur

●Abnormal upper or lower extremity pulses

●Rib fractures

●Pulmonary contusion

●Pneumothorax or hemothorax

A retrospective review of patients younger than 18 years with sternal fractures (n = 3160) reported that the most common associated thoracic cavity injury was pulmonary contusion (47 percent), while BCI occurred in only 3 percent [95]. In other retrospective reviews, BCI in children was often associated with pulmonary contusion, rib fractures, pneumothorax, hemothorax, and spinal fractures [89,93]. Signs of heart failure or hypotension in the setting of blunt thoracic trauma may be caused by BCI, but these findings are absent in many children and hypotension is far more likely to be due to hemorrhage. In the same retrospective series cited above, less than 25 percent of children with BCI had an abnormal cardiac examination. Of those with isolated BCI, 26 percent were hypotensive in the emergency department and less than 9 percent had signs of heart failure.

Evaluation and diagnosis — The diagnostic approach to BCI in children is similar to adults (see 'Our approach' above). In a child with significant (ie, high energy mechanism) chest trauma, our approach is the following:

●Perform a bedside ultrasound (FAST examination) early in the assessment of any child with blunt thoracic trauma who is hemodynamically unstable. Ultrasound is ideal for identifying hemopericardium. If no hemopericardium is present but there is persistent concern for cardiogenic shock, a formal transthoracic echocardiogram looking for wall motion or valvular/septal abnormalities should be obtained. In younger children, a transthoracic echocardiogram is generally preferred because it is less invasive, less difficult to perform, and usually provides sufficient information. (See "Trauma management: Approach to the unstable child", section on 'e-FAST (extended focused assessment with sonography for trauma)'.)

●Obtain a plain chest radiograph. In cases of BCI, the radiograph may demonstrate cardiomegaly or reveal noncardiac injuries (eg, pulmonary contusions, rib fractures, hemothorax, pneumothorax).

●Obtain an electrocardiogram (ECG) in a child with chest pain, tenderness, chest wall ecchymosis, abnormal heart sounds, abnormal upper or lower extremity pulses, or radiograph with any of the above findings. (See 'Electrocardiogram' above.)

●We obtain a troponin as an adjunct in a child who is either clinically symptomatic (eg, dysrhythmia, hypotension) or who has abnormal findings on chest radiograph or ECG. A normal troponin and ECG can be helpful to exclude BCI in a child with an abnormal chest radiograph [93]. We do not recommend obtaining a troponin in an asymptomatic child.

When clinical and ECG findings suggest that BCI, rather than hemorrhage, may account for a child's hemodynamic instability, immediate transthoracic echocardiography should also be performed. Hemodynamically stable children with a normal sinus rhythm are unlikely to develop a dysrhythmia or cardiac insufficiency [89].

As with adults, the appropriate use of cardiac troponin in the evaluation of children with possible BCI remains unclear. BCI is unlikely in an asymptomatic child with a cardiac troponin less than 1.05 mcg/L at presentation and again within the first six hours of admission (it should be noted that baseline and threshold values for troponin vary by institution and assay) [65,96]. In addition, the clinical significance of an elevated troponin is questionable in a hemodynamically stable child with no examination findings suggestive of BCI and a normal ECG and chest radiograph.

Conversely, any child with an abnormal ECG and elevated troponin following blunt thoracic trauma warrants evaluation with transthoracic echocardiography and admission or close observation, including cardiac monitoring, for at least 24 hours.

Management — The general management and disposition of children with blunt thoracic trauma is discussed separately (see "Thoracic trauma in children: Initial stabilization and evaluation"). In general, any child who has sustained significant blunt chest trauma and manifests any of the findings listed below suggestive of BCI should be admitted for observation, even in the absence of intrathoracic or intraabdominal injuries detected on imaging studies:

●Hemodynamic instability

●Abnormal ECG findings, including persistent sinus tachycardia

●Elevated cardiac troponin in association with concerning symptoms, signs, or abnormalities on ECG or cardiac monitoring

Definitive management of BCI in children depends upon the specific injury sustained. Cardiac sequelae (such as mitral or tricuspid insufficiency or ventricular septal defect) may develop as the result of BCI. Consequently, all children with confirmed or suspected BCI should have a follow-up evaluation by a cardiologist with pediatric expertise [89].

PITFALLS

●Attributing shock in a trauma patient to cardiac injury rather than hemorrhage.

●Assuming that blunt cardiac injury (BCI) with hemodynamic abnormalities is due to contused myocardium alone and not obtaining an echocardiogram to look for more severe injury (eg, valvular or septal rupture, pericardial tamponade).

OUTCOMES — Outcome for patients with blunt cardiac injury (BCI) correlates with the clinical findings at presentation. Factors associated with increased mortality include a high trauma severity score (eg, Injury Severity Score or Organ Injury Scale), a shorter time to diagnosis (implying more significant clinical findings), cardiac tamponade or rupture, absence of vital signs on admission, and coexistent injury to the aorta, liver, spleen, or kidneys [97]. When the diagnosis is made due to an abnormal ECG or cardiac biomarker alone, outcome is favorable, with no long term sequelae in the majority of patients [69,98,99].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues of trauma management in adults" and "Society guideline links: Thoracic trauma".)

SUMMARY AND RECOMMENDATIONS

●Definitions – Blunt cardiac injury (BCI) is a poorly characterized disease with varied presentations and no clear diagnostic criteria. Injuries may include rupture of the ventricular or atrial wall, septum, or a valve; cardiac dysfunction; dysrhythmia; or, rarely, myocardial infarction. (See 'Epidemiology, definitions, and scoring' above and 'Types of injury' above.)

●Dysrhythmia and structural injury – Standard ACLS protocols are used to manage dangerous dysrhythmia. The focused assessment with sonography for trauma (FAST) examination is an excellent screening test for clinically significant hemopericardium, which suggests ventricular wall rupture. Immediate surgical consultation is required for severe injury, such as a valve tear, or septal or ventricular wall rupture. (See 'Dysrhythmia' above and 'Valve, septum, or ventricular wall injury' above.)

●Cardiology consultation – Echocardiography and cardiology consultation are necessary for any patient with blunt thoracic trauma and a complex dysrhythmia, cardiac dysfunction, diastolic murmur (not known to be old), or signs of heart failure. (See 'Our approach' above and 'Echocardiogram' above.)

●Stable patient at risk for BCI – Screening with serial electrocardiograms (ECGs), cardiac monitoring, and observation for four to six hours is sufficient in the hemodynamically stable patient with a FAST without hemopericardium for whom there is concern about BCI (algorithm 1). We obtain cardiac biomarkers in a patient with ECG abnormalities, symptoms/comorbidities suggestive of acute coronary syndrome, abnormal heart sounds (eg, muffled sounds, holosystolic or diastolic murmur), or signs of hemodynamic instability or heart failure. We do not routinely obtain cardiac biomarkers in the stable patient with blunt chest trauma in the absence of ECG abnormalities. (See 'Our approach' above and 'Cardiac biomarkers' above.)

●Child at risk for BCI – The chest wall of a child is more compliant than the adult and therefore during blunt thoracic trauma more kinetic energy can be transmitted to a child's intrathoracic structures without bony injury. Thus, BCI can be difficult to diagnose in children because external signs of injury may be minimal or absent. When present, such external signs, focal tenderness over the upper thorax, or abnormal findings on the cardiac or pulse examinations raise the possibility of BCI. (See 'Pediatric considerations' above.)