Blunt cardiac injury

Most commonly a result of sudden deceleration or direct precordial impact, blunt cardiac injury (BCI) encompasses a spectrum of structural and functional cardiac derangements which may occur after trauma to the heart ⁷.

Terminology

While sometimes referred to with general terms such as "cardiac contusion," blunt cardiac injury represents a spectrum of injuries which may be stratified based on injury severity (the AAST organ injury scale is sometimes used) or anatomical structure affected. 

Epidemiology

Blunt cardiac injury may account for an estimated 20% of fatalities occurring as a result of a motor vehicle collision ³.

Clinical presentation

Presenting symptoms may be non-specific, vary greatly, and appear attributable to coexisting injuries and/or pre-existing medical conditions including:

• chest pain
• dyspnea
• palpitations
• presyncope

ECG

Features on the electrocardiogram include ⁷:

• sinus tachycardia
• pathologic Q wave formation
• elevation of the ST segment
• new bundle branch blocks and/or atrioventricular (AV) nodal blocks
• ventricular fibrillation
  • in the context of an injury not producing structural damage referred to as commotio cordis

Radiographic features

Plain radiograph

A chest radiograph may demonstrate associated features, including:

• sternal fracture
• rib fracture(s)

Ultrasound

Sonographic features of blunt cardiac injury are highly variable. Manifestations detectable by transthoracic echocardiography may appear as follows, based on the structure injured ⁴:

• ventricular septal rupture
  • new ventricular septal defect
• cardiac rupture
  • most commonly of the left ventricle
  • in surviving patients, right atrial injury is more common, which may result in:
    • pericardial effusion
    • cardiac tamponade
• coronary arterial injury
• valvular injury
  • may include disruption of the subvalvular apparatus
    • chordae tendinae rupture
    • papillary muscle rupture
  • aortic valve the most commonly involved
    • aortic regurgitation
  • tricuspid valve also commonly affected
    • tricuspid regurgitation
  • mitral annular disruption also reported, with mitral regurgitation
• contractile dysfunction
  • most commonly of the left ventricle
    • regional wall motion abnormalities
    • global depression of systolic function
• pericardial laceration
  • appearance of the air gap sign ²

Transesophageal echocardiography is considered a superior modality, also highly sensitive for associated great vessel injuries, including ³:

• thoracic aortic rupture
  • vast majority occur at the isthmus
    • pseudocoarctation pattern is characteristic, with a spectral Doppler derived pressure gradient across the isthmus exceeding 20 mmHg
  • periaortic hematoma
  • hemopericardium
  • hemothorax