Blunt Cardiac Injury (BCI)

Posted by Marco Torres on

Friday, 2300 hours:

A 24 year-old woman presents to your Emergency Department after a motor vehicle collision. She was the restrained driver of a car that collided head-on with another vehicle. She is complaining only of chest pain and appears uncomfortable and anxious. The monitor shows sinus tachycardia and you spot a sternal fracture on her chest x-ray. After IVF and Fentanyl, she remains slightly tachycardic and you wonder:

  • Do I need to send a troponin?
  • If the troponin is negative does this patient need to be admitted?
  • What other testing should I consider in the Emergency Department?

Blunt Cardiac Injury

Definition: There is no standard definition of blunt cardiac injury (BCI). In general, BCI refers to any blunt trauma to the heart. This can range from mild to severe injuries including:

  • Cardiac contusions
  • Dysrhythmias after trauma
  • Ventricular wall rupture

Epidemiology:

  • Estimated incidence of BCI in thoracic trauma varies greatly with reported values ranging from 8 to 71%. This large range results from a lack of clear definition and diagnostic criteria. (Pasqaule 1998 , Singh 2018 )
  • One recent study found a BCI incidence of 25% among patients with blunt thoracic trauma. (Emet 2010 )
  • Most commonly injured anatomy (Anterior Structures):
    • Right ventricle
    • Right atrium
  • Less commonly injured:
    • Left ventricle and atrium
    • Septum, valves, and coronary arteries (extremely RARE). (Karalis 1994 )

Causes:

Suspect BCI in any patient with significant thoracic trauma or direct precordial impact including:

  • Motor vehicle accidents (most common)
  • Pedestrians struck by motor vehicles
  • Crush injuries
  • Blast injuries
  • Deceleration injuries

A significant amount of force is normally required for BCI to occur. Up to 20% of death due to motor vehicle crashes is attributed to BCI. (Schultz 2004 , Singh 2018 )

A word (or two) in Latin…

Commotio Cordis (Borjesson 2009 )

  • Latin for “disturbance of the heart”
  • Second leading cause of death in young athletes after hypertrophic cardiomyopathy (HCM)
  • Sudden death after a seemingly low-impact blow to the chest by a hard projectile most commonly
    • Baseballs
    • Lacrosse balls
    • Hockey pucks
  • The fatal nature of the blow requires an unlucky combination of impact location, velocity, and projectile hardness occurring just milliseconds before the peak of a T wave
  • This results in ventricular fibrillation followed by sudden death

Pathophysiology:

The pathophysiology of BCI depends upon which of the injuries has occurred

  • Pericardial injury:Pericardial laceration, perforation, hematoma
  • Atrial and Ventricular injury
    • Wall rupture
    • Myocardial contusions (most common and most innocuous)
  • Valvular injury: Cardiac valve, papillary muscle, and chordae tendineae tears or ruptures
  • Coronary vessel injury
    • Intimal disruption
    • Thrombosis
    • Dissection

Signs & Symptoms:

  • Symptoms:
    • Most common symptom is chest pain
    • Symptoms will widely depend on the extent of BCI
  • Signs:
    • Dysrhythmias (most commonly sinus tachycardia, atrial fibrillation)
    • Chest wall deformities or ecchymosis
    • Pulse deficits
    • Hypotension
    • New murmurs
    • New heart failure
      • Rales
      • Muffled heart sounds
      • Distended neck veins
    • Pericardial effusion or tamponade

The most severe BCIs result in wall rupture in any of the chambers and these patients typically do not survive to ED presentation. (Shorr 1987 , Calhoon 1986 , Yousef 2014 )

Pediatric patients have increased compliance of the thoracic cavity and there may be no outward signs of trauma to raise suspicion of BCI.

Associated Injuries (Schultz 2004 ):

  • Head injury
  • Extremity injury
  • Rib fracture
  • Aortic injury
  • Hemothorax
  • Pulmonary contusion
  • Pneumothorax
  • Flail chest
  • Sternal fracture
  • Abdominal solid organ injury
  • Spinal injury

Immediate Management:

  • Clinicians should proceed with initial stabilization of the trauma patient
  • Hypotension in the trauma patient should be initially approached as due to hemorrhage rather than from a purely cardiac cause
  • A FAST (Focused Assessment with Sonography for Trauma) exam should be performed immediately after the primary survey is completed
  • Consider an “Extended” exam (EFAST) and include views of the anterior thorax to evaluate for pneumothorax
  • Persistent tachycardia after volume resuscitation, adequate pain control, and exclusion of intrathoracic or intraabdominal hemorrhage should raise suspicion of possible BCI

Testing and Treatment:

  • Electrocardiogram
    • 12-lead EKG is an important screening tool in the patient with potential BCI and can quickly guide the patient’s disposition
    • New abnormalities on EKG such as
      • Dysrhythmias (i.e. atrial fibrillation)
      • Conduction delays (bundle branch blocks)
      • ST segment elevations or depressions warrant continued telemetry monitoring
    • The most common rhythm encountered after BCI is sinus tachycardia followed by atrial fibrillation
    • EKGs should be repeated with any change in the patient’s symptomatology or hemodynamic status

EKG Findings in Blunt Cardiac Injury (Foil 1990 ):

  • Chest X-ray
    • Helpful initial test to evaluate thoracic trauma
    • Certain injuries visible on x-ray are commonly associated with but do not guarantee BCI:
  • Echocardiography
    • Part of a comprehensive evaluation for BCI
    • Pericardial effusions and tamponade should be ruled out early with FAST exam
    • Transthoracic Echocardiography (TTE)
      • Can be performed at the bedside by EM physicians
      • Provides an impression of:
        • Overall cardiac contractility (organization, ejection fraction)
        • Wall motion abnormalities
        • Turbulent blood flow
        • Intraventricular or intraatrial thrombi
      • Visualization limited in up to 1/3 of patients due to poor echocardiographic views
    • Transesophageal Echocardiography (TEE) is more sensitive in detecting injuries that require intervention (wall and valve ruptures)
    • Time to surgery was significantly shorter for patients with BCI identified on TEE. (Chirillo 1996 )
    • TTE should be repeated with any change in the patient’s status (Chirillo 1996 , Labovitz 2010 )
  • Cardiac biomarkers
    • Utility of cardiac biomarkers such as troponin remains unclear
    • Presence of a single elevated troponin does little to help guide further management or intervention except for increasing the likelihood of admission and cardiology consultation
    • Optimal timing for troponin measurement remains unknown
    • A review of prospective studies demonstrated that a negative troponin had 100% negative predictive value for subsequent cardiac complications (Guild 2014 ). However, the ideal timing of checking that troponin is unknown
    • Elevations in troponin can also be attributed to significant non-thoracic trauma
    • CK-MB is not a recommended biomarker in BCI and has not been shown to correlate with morbidity or mortality from BCI (Fulda 1997 )
    • There is no gold standard or recommendation for the routine use of cardiac biomarkers to characterize or prognosticate BCI
  • Chest Computed Tomography (CT)
    • CT with significant thoracic trauma raises the suspicion for BCI and should lead to further investigations
    • CT is not sensitive as it has been shown to miss injuries then found on echo (Hammer 2016 )

Published Guidelines:

  • The Eastern Association for the Surgery of Trauma (EAST) published a set of guidelines for the evaluation and care of those with BCI: (Clancy 2012 )
  • Level 1 Evidence:
    • Obtain an electrocardiogram (EKG) on all patients with suspected BCI
  • Level 2 Evidence:
    • If the EKG reveals a new abnormality (dysrhythmia, ST changes, heart blocks), admit the patient for continuous EKG (telemetry) monitoring. Compare to a previous EKG whenever available
    • BCI can be ruled out in patients with a normal EKG and a negative troponin I although the optimal timing of troponin measurement remains undetermined
    • Obtain an optimal TTE or a TEE on patients who are hemodynamically unstable or with persistent new arrhythmias
    • Those with sternal fractures but also with a normal EKG and troponin I do not have to be continuously monitored
    • Troponin I are the preferred cardiac enzymes. Creatinine phosphokinase levels are not useful
    • Nuclear studies offer little when compared with Echocardiography and do not need to be obtained routinely
  • Level 3 Evidence:
  • Among patients with BCI, surgery is not contraindicated, given appropriate monitoring in
    • The elderly with known cardiac disease
    • Hemodynamically unstable patients
    • Those with new EKG abnormalities on admission
  • Measure troponin I on patients with suspected BCI. If elevated, admit to a monitored setting and follow serial troponins although the best timing of measurement has not been determined
  • Cardiac CT or MRI can be useful in differentiating acute MI from BCI to help guide further management

Take Home Points

  • No single test can be used to exclude BCI. However a thorough physical exam combined with a 12-lead EKG, troponin measurement, and echocardiography can be used to characterize BCI and direct care
  • Obtain a 12-lead EKG in all thoracic trauma patients
  • A chest x-ray may help to identify associated injuries. However, isolated musculoskeletal injuries such as sternal fractures do not correlate with a risk of BCI
  • Bedside TTE can quickly evaluate for life-threats such as cardiac tamponade; A TEE is both sensitive and specific across the spectrum of BCI pathology and is part of a comprehensive evaluation
  • BCI can be excluded in a patient without EKG abnormalities and a negative troponin I

Guest Post By:

Katrina D’Amore, MD
PGY-4 Resident
St. Joseph’s Regional Medical Center Emergency Department

References:

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Post Peer Reviewed By: Anand Swaminathan, MD (Twitter: @EMSwami) and Salim Rezaie, MD (Twitter: @srrezaie)

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