Blunt cardiac injury (BCI) is most commonly the result of sudden deceleration or direct precordial impact and encompasses a spectrum of structural and functional cardiac derangements that may occur after trauma to the heart 7.
On this page:
Terminology
While sometimes referred to with general terms such as cardiac contusion, blunt cardiac injury represents a spectrum of injuries that may be stratified according to injury severity (the AAST injury scoring 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.
Injury occurs from several mechanisms 11-12:
direct precordial blunt trauma
cardiac compression between the sternum, ribs and thoracic spine
laceration from displaced sternal and rib fractures
indirect forces transmitted from below the diaphragm
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
dyspnoea
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
premature ventricular contractions 8
Radiographic features
Plain radiograph
A chest radiograph may demonstrate cardiac signs or associated traumatic features, including:
cardiomegaly due to pericardial effusion
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
-
cardiac rupture
most commonly of the left ventricle
-
in surviving patients, right atrial injury is more common, which may result in:
coronary arterial injury
-
valvular injury
-
may include disruption of the subvalvular apparatus
chordae tendinae rupture
papillary muscle rupture
-
aortic valve the most commonly involved
-
tricuspid valve also commonly affected
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
Transoesophageal echocardiography (TOE) is considered a superior modality, also highly sensitive for associated great vessel injuries, including 3:
-
-
vast majority occur at the isthmus
pseudocoarctation pattern is characteristic, with a spectral Doppler derived pressure gradient across the isthmus exceeding 20 mmHg
-
CT
CT imaging features of blunt cardiac injury are can be divided into direct and indirect signs 8-12:
-
direct
-
focal or diffuse myocardial hypoenhancement
right ventricular contusion is more common due to the anterior position of the ventricle but less commonly visible on CT due to the thick wall thickness
has a sharp border with normal myocardial (c.f. myocardial infarction)
focal or diffuse myocardial thickening and oedema
-
myocardial rupture
very rare as almost always fatal
most commonly affects the right ventricle (due to anterior position and thinner wall)
ventricular septal rupture which can be immediate or up to 48 hours delayed
-
abnormal ventricular wall motion
on ECG-gated functional cardiac CT which is not perfromed in the usual trauma CT protocol
-
focal coronary artery dissection, thrombosis or occlusion
on ECG-gated CTCA which is not perfromed in the usual trauma CT protocol
LAD is the most commonly affected vessel
-
valve disruption
mitral and aortic valve injuries are most common
papillary muscle rupture
pericardial laceration with or without cardiac herniation
-
-
indirect
pneumopericardium
mediastinal fat stranding or haemomediastinum
pulmonary contusions or lacerations
anterior rib fractures
Iatrogenic injuries may also be seen such as a malpositioned intercostal catheter in the pericardial space or a cardiac chamber.
Differential diagnosis
-
myocardial infarction causes focal ventricular myoardial hypoenhancement
infarct usually has a indistint border and is confined to an arterial terrritory 11