Written by: Paul Trinquero, MD (NUEM PGY-4) Edited by: Victor Gappmaier, MD (NUEM Alum '18) Expert commentary by: Emily Koeck, MD
A 39-year-old male presents as a fall from a two-story window, landing on his left side. He lost consciousness after the fall but is now back to his baseline mental status. Primary survey is intact and his GCS is 15. Secondary survey is notable for a left temporal scalp hematoma and tenderness over his left anterior chest. A CT brain and CT cervical spine are obtained and both are unremarkable. CT chest is notable for two left sided rib fractures and a small underlying pulmonary contusion, without any evidence of hemothorax or pneumothorax. Given his high-risk mechanism for blunt cardiac injury, ECG and troponin are obtained. Troponin is negative but ECG demonstrates a right bundle branch block, with no prior for comparison. The patient remains well appearing and hemodynamically stable. He is asymptomatic other than mild chest wall pain. This typical multiple blunt trauma patient raises some interesting questions:
What is blunt cardiac injury and how is it diagnosed?
What are the potential complications and how should they be addressed?
Do all patients with chest trauma need an ECG? Troponin?
What about isolated sternal fractures?
What findings merit an emergent echo?
When should an otherwise well appearing patient be admitted for observation?
Overview of Blunt Cardiac Injury (BCI)
Blunt Cardiac Injury (BCI) encompasses a spectrum of disease caused by significant blunt force transmitted to the heart via a deceleration injury or direct blow to the precordium. Damage is done as a result of direct compression of the heart between the sternum and spine, increased intra-thoracic pressure, deceleration forces (the heart has relatively unrestricted movement in the AP direction so abrupt deceleration can cause a significant impact with the sternum), or direct trauma from fractured ribs1
BCI is an umbrella term that includes a spectrum of potential pathology such as:
Comotio Cordis: sudden death due to an ill-timed force during a period of electrical vulnerability
Cardiac rupture: traumatic rupture of the myocardium due to compression of a full chamber during early systole or raid deceleration forces shearing the atria from the vena cava or pulmonary veins. Often identified on autopsy due to roughly 90% fatality within minutes
Pericardial rupture and cardiac herniation: very rare. Most likely will either result in death before arrival or will not be the direct cause of death.
Valvular injury: laceration of aortic cusps can cause aortic insufficiency. Compression of heart during systole can lead to tearing of mitral valves and/or papillary muscle rupture.
Septal tear: traumatic ASD or VSD are less common pathological findings identifiable by characteristic loud holosystolic murmurs and echocardiography
Coronary artery dissection/thrombosis: rare to occur in isolation
Myocardial contusion: edema and necrosis of cardiac myocytes due to blunt traumatic injury
Of the above injuries, most are relatively easy to diagnosis. Comotio cordis, by definition, is not survivable. Cardiac rupture leads to immediate death in most cases, but if a stable hematoma forms, the patient may present alive and in tamponade, which can be identified clinically and with the aid of bedside ultrasound. Isolated pericardial rupture is very rare. It can be associated with cardiac herniation and subsequent impairment in cardiac output, which will manifest with unstable vitals or could be identified on echo. Valvular or septal injuries will often present with heart failure, and most will be associated with a loud, new murmur and/or hemodynamic instability. Coronary artery dissection is exceedingly rare, but diagnosis (ECG, troponin) and treatment (cardiology consultation, PCI) are similar to regular MI and not unfamiliar to the emergency physician. That leaves myocardial contusion, which is the subject of considerable debate and will be discussed in detail below.
There is no clear-cut definition or gold standard diagnosis for myocardial contusion. Pathologically, a cardiac contusion involves edema and necrosis of myocytes as well as patchy areas of hemorrhage, similar to that seen with an MI. Hence, cardiac troponins are very specific for myocardial injury from trauma just as they are for ischemic damage. Serum levels are elevated much more rapidly than after MI, however some sources recommend a 4-6 hr delta troponin depending on time of initial presentation and level of suspicion.[2,3] However, cardiac contusions can occur in the absence of troponin elevation and can be variably diagnosed via TTE, TEE, or ECG. Although frequently encountered in high-risk poly-trauma patients, the vast majority of cardiac contusions tend to improve spontaneously and will heal with scar formation. They are generally well tolerated and may produce only minimal symptoms. Prognosis is excellent both in-hospital and at 3 and 12 month follow up and patients who are initially clinically stable are very unlikely to deteriorate due to cardiac contusion. There are two mechanisms by which blunt cardiac injury can lead to significant morbidity and mortality: significant contractile dysfunction and arrhythmia.
Significant contractile dysfunction is easy to identify by assessing the patient’s vital signs. A hemodynamically stable, asymptomatic patient is unlikely to be suffering from serious traumatic heart failure. Conversely, patients with hemodynamic instability or persistent arrhythmia should have an emergent echocardiogram to assess for a structural abnormality or hemodynamically significant contusion.
Arrhythmia may have a delayed presentation in an otherwise asymptomatic patient. Therefore, “at risk” patients may benefit from a telemetry admission in order to identify and treat expeditiously. Twenty four hours is an appropriate duration for monitoring because evidence suggests that arrhythmia will almost always manifest within the first 24 hours.[2,5] To screen for those at risk, the Eastern Association for the Surgery of Trauma (EAST) guidelines strongly recommend an ECG on all patients with a potential mechanism. Common mechanisms include motor vehicle collisions, falls from height, and crush injuries. In terms of defining a high-risk mechanism, the EAST guidelines are not specific, but many individual institutions specify particular speeds or characteristics of MVC or particular heights of falls that merit screening for BCI.
Of note, while an isolated sternal fracture is clearly indicative of significant force transmitted to the thoracic cavity, is should be thought of as a risk factor for BCI rather than pathognomonic. Only a small percentage of patients with isolated sternal fracture wind up with a cardiac contusion. Hence, patients with sternal fracture should be screened (with an ECG and troponin as discussed above), but should not be immediately labeled with a diagnosis of myocardial contusion or blunt cardiac injury.
Prior guidelines hedged on the utility of a troponin, but the new 2012 EAST guidelines acknowledge several recent studies which have shown that a normal ECG alone may not be sufficient to rule out clinically significant BCI and that the addition of a negative troponin increases negative predictive value to 100%. Patients with a normal ECG and negative troponin can be ruled out for BCI. This guideline is partially based on a prospective study, which evaluated 333 patients with significant thoracic trauma and concluded that patients with a normal ECG and a negative delta troponin (at 0 and 8 hrs) could be safely discharged if they lacked other criteria for admission. Patients with either an ECG abnormality (arrhythmia, ST changes or evidence of ischemia, heart block) or an elevated troponin should be admitted for telemetry monitoring for 24 hours.
Our patient from above was admitted for 24 hour monitoring given his abnormal initial ECG. In addition to pain control, incentive spirometry, and supportive care for his rib fractures, he was monitored on telemetry given his elevated risk of dysrhythmia from a likely cardiac contusion. Fortunately, he had an uneventful hospital stay, repeat ECG showed resolution of the prior bundle branch block, and he was discharged the following afternoon.
Blunt cardiac injury (BCI) is an umbrella term encompassing a wide spectrum of pathology due to blunt thoracic trauma.
Hemodynamically unstable patients should receive an emergent echo. This will help to identify structural abnormalities such as cardiac, septal, or pericardial rupture, valvular disruption, or hemodynamically significant cardiac contusion.
At-risk patients should be screened with an ECG and a troponin. If both are normal, then clinically significant BCI is unlikely.
Isolated sternal fracture is a risk factor for BCI and should prompt screening with ECG and troponin, but is not pathognomonic and does not mandate additional BCI workup on its own
Patients with an abnormal ECG or an elevated troponin should be admitted for telemetry monitoring for 24 hours to ensure timely treatment if the patient develops a dysrhythmia.
Excellent overview of a broad and complicated topic; just a few points to clarify/emphasize. As you stated, blunt cardiac injury is truly a spectrum of injuries related to the delivery of significant force to the precordium/chest wall. For the most part, these patients are either stable or nearly dead. The truly serious injuries, such as comotio cordis or free cardiac/pericardial rupture, are generally fatal prior to hospital arrival. Blunt valvular injury tends to be hemodynamically significant and should be suspected in a patient with signs of cardiogenic shock or murmur. While the overall incidence of BCI in the setting of thoracic trauma ranges from 13-76%, it is rare to have serious complications from BCI, and most patients who are alive on arrival to the hospital have minor cardiac injuries. These are usually myocardial contusions or dysrhythmias, and tend to be asymptomatic and self-resolve within 24 hours.
Given the high incidence of BCI and poor sensitivity of physical exam, all patients with an appropriate mechanism should be screened with EKG and troponin. A normal EKG and negative troponin is sufficient to rule OUT blunt cardiac injury. Patients with EKG changes and/or positive troponins should be stratified by hemodynamics and clinical stability. Stable patients should be observed with telemetry for resolution of EKG changes, with serial EKG and troponins depending on the degree of abnormality. Any unstable patient with risk factors for BCI should undergo emergent echocardiography to identify a possible serious injury that would require intervention.
As a final note, the risk factors for BCI are also risk factors for aortic injury, so make sure to evaluate the aorta in unstable or symptomatic patients.
Emily Koeck, MD
Surgical Critical Care, Trauma, and Burn Fellow, John H. Stroger, Jr. Hospital of Cook County
How To Cite This Post
[Peer-Reviewed, Web Publication] Trinquero P, Gappmaier V (2018, September 10). Blunt Cardiac Injury. [NUEM Blog. Expert Commentary by Koeck E]. Retrieved from http://www.nuemblog.com/blog/BCI
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