Myocardial Contusion, Emergency Medicine

Basics

Description

Also known as blunt cardiac injury
Pathologically characterized by discrete and well-demarcated area of hemorrhage
Usually subendocardial
May extend in pyramidal transmural fashion
Most commonly involves anterior wall of right ventricle or atrium due to anatomic location

Etiology

Blunt trauma to chest:
- High-speed deceleration accidents
- May occur in accidents with speeds as low as 20 " 35 mph
Auto " pedestrian injuries
Falls
Prolonged closed-chest cardiac massage
Heart may be compressed between sternum and vertebrae.
Heart strikes sternum during deceleration.
Heart is damaged by abdominal viscera upwardly displaced by force on abdomen.
Concussive forces (e.g., explosion)
Associated conditions:
- Life-threatening dysrhythmias
- Cardiogenic shock/CHF
- Hemopericardium with tamponade
- Valvular/myocardial rupture
- Intraventricular thrombi
- Thromboembolic phenomena
- Coronary artery occlusion from intimal tearing or adjacent hemorrhage and edema may rarely occur.

Diagnosis

Signs and Symptoms

Clinical picture is varied and nonspecific:
- Chest pain
- Cardiogenic shock
- Subtle EKG changes without clinical symptoms
Most common sign is tachycardia out of proportion to degree of trauma or blood loss.
Friction rub may occur rarely.
Retrosternal chest pain unrelieved by nitroglycerin:
- Often delayed up to 24 hr
- May respond to oxygen
Evidence of significant thoracic trauma:
- Contusions, abrasions
- Palpable crepitus
- Sternal fracture alone with normal EKG and negative serial troponin I does not predict BCI
- Visible flail segments
Other injuries may mask signs and symptoms of myocardial contusion.

History

Mechanism of injury (e.g., MVA, fall, explosion, missile to chest wall)
Any syncope or loss of consciousness suggests possible dysrhythmia.
Crush injury

Obtain and consider pre-existing cardiac disease and concurrent medications in elderly patients following blunt cardiac injury.
Due to increased compliance of pediatric chest wall, significant cardiac compression and contusion may be present with minimal or no external signs of trauma.
Physical Exam
Complete physical exam as in any trauma patient:

Evaluate for jugular venous distention (JVD)
Decreased or muffled heart sounds
Extra heart sounds
Crepitus
Pulsus paradoxus
Evidence of chest wall trauma

Essential Workup

No single diagnostic study (other than autopsy findings!) confirms presence of myocardial contusion.
EKG:
- Best initial screening tool
- Most common rhythm is sinus tachycardia (70%).
- Normal EKG does not rule out myocardial damage.
- EKG changes may be subtle or include nonspecific findings such as ST changes, right bundle branch block, and premature atrial and ventricular contractions.
- At least 1 repeat EKG is recommended because changes may occur over time.
- Serious dysrhythmias may result in hemodynamic instability:
  - Atrial fibrillation/atrial flutter
  - Ventricular tachycardia/ventricular fibrillation (commotio cordis)
Troponin I is now the recommended screening lab test over CK-MB to be interpreted with EKG.
Echocardiography should be performed on all patients with any EKG changes, elevated troponin I or troponin T.
Transesophageal ECG (TEE) more sensitive than transthoracic ECG (TTE) but technically more difficult and time-consuming.
Multidetector CT angiography or MRI may be of benefit.

Diagnosis Tests & Interpretation

Lab

Troponin I is the preferred lab test.
Troponin T less sensitive than troponin I.
- Levels should be sent on all patients where BCI suspected.
- Should be repeated at 6 " 8 hr after injury.
- Any elevation requires admission.
Cardiac troponins are more specific than CK-MB for cardiac injury.
CK-MB no longer routinely recommended.

Imaging

Radiographs, CT, MRI detect associated injuries:
- Pulmonary contusion
- Rib or sternal fractures
- Acute pulmonary edema
- No specific findings in cardiac contusion
Focused assessment with sonography for trauma (FAST) should be performed on all patients to assess pericardium and possible concurrent intra-abdominal injuries.
ECG:
- Generally regarded as best imaging study for detecting cardiac contusion
- Detects wall-motion abnormalities and effusions
- Allows direct visualization of cardiac chambers and valves
- May not visualize small (possibly clinically insignificant) contusions
- TEE preferable to TTE if patient stable enough for procedure.
- TTE may be performed although may also visualize great vessels.
Radionuclide ventriculography:
- Has been largely abandoned owing to wide availability of ECG
Thallium201 scintigraphy (single photon emission CT [SPECT]):
- Sensitive and specific to left ventricular injury
- Unable to evaluate right ventricle, which is most commonly injured

Diagnostic Procedures/Surgery

Pericardiocentesis:
- For treatment of cardiac tamponade, preferably under US guidance
Thoracotomy:
- Consider in patient with acute cardiac arrest or decompensation in ED or after unsuccessful pericardiocentesis

Differential Diagnosis

Cardiac rupture
Tamponade
Valvular damage
Other traumatic chest wall injury
Angina or MI

Treatment

Pre-Hospital

Pre-hospital personnel should convey accurate information to emergency department personnel:

Mechanism of injury
Motor vehicle status
Steering wheel and dashboard damage
Use of restraint devices
Vehicle speed
Patient position
Time to extrication
Any loss of consciousness

Initial Stabilization/Therapy

Manage airway and resuscitate as indicated:

Oxygen:
- IV access
- Cardiac monitoring

Ed Treatment/Procedures

Dysrhythmias may be treated with same pharmacologic agents used for nontraumatic dysrhythmias:
- Supraventricular tachycardia:
  - Adenosine or calcium channel blocker if patient not hypovolemic
- Bradycardia:
  - Atropine
  - Pacing
- Ventricular dysrhythmias:
  - Electrical conversion
  - Amiodarone
  - Lidocaine
  - Procainamide
- Cardiac arrest:
  - Epinephrine
  - Atropine
  - Other interventions as appropriate
- Rapid atrial fibrillation or flutter:
  - Diltiazem, or digoxin if patient not hypotensive
Prophylactic treatment of dysrhythmias is not indicated.
Cardiogenic shock caused by myocardial contusion:
- Judicious fluid administration
- Inotropic support (dopamine or dobutamine)
- Intra-aortic balloon counterpulsation may be necessary.

Medication

Medications used in cardiac contusion are supportive for dysrhythmias or hemodynamic compromise secondary to injury.
There is no primary therapy for cardiac contusion.
Adenosine: 6 mg rapid IVP (peds: 0.05 " 0.1 mg/kg rapid IVP), may repeat 12 mg q1 " 2min twice if no response
Amiodarone: Load 150 mg IV over 10 min (peds: 5 mg/kg), then 1 mg/min for 6 hr, then 0.5 mg/min (peds: 5 Όg/kg/min)
Atropine: 0.5 " 1 mg (peds: 0.02 mg/kg/dose, min. 0.1 mg) IV or endotracheal tube (ET)
Digoxin: Load 0.5 mg (peds: 0.02 mg/kg) IV, then 0.25 mg (peds: 0.01 mg/kg) IV q6h for 2 more doses
Diltiazem: 0.25 mg/kg IV for both adults and peds over 2 min, may rebolus 0.35 mg/kg (adult and peds) 15 min later
Dobutamine: 2 " 15 Όg/kg/min (adults and peds)
Dopamine: 2 " 20 Όg/kg/min (adults and peds)
Epinephrine: 1 mg (peds: 0.01 mg/kg) IV or ET for cardiac arrest (1:10,000 solution)
Lidocaine: Load 1 mg/kg IV, then 0.5 mg/kg q8 " 10min to max. 3 mg/kg (adults and peds); infusion 1 " 4 mg/min (peds: 20 " 50 Όg/kg/min) IV
Procainamide: start at 3 to 6 mg/kg/dose over 5 minutes not to exceed 100 mg to a titrated maximum of 15 mg/kg/loading dose
Verapamil: 0.1 " 0.3 mg/kg up to 5 " 10 mg IV over 2 min (not approved in children)

Follow-Up

Disposition

Adverse outcomes, particularly dysrhythmias, are uncommon but generally occur within 1st 24 hr.
No single test or combination of tests will accurately predict which patients can be discharged safely from ED:
- All patients in whom diagnosis is seriously being entertained should be admitted to a monitored setting.

Admission Criteria

EKG abnormalities
Cardiac enzyme abnormalities
Hemodynamic instability
Other studies suggesting cardiac contusion
Admit to monitored unit for close observation.

Discharge Criteria
Asymptomatic patients with no EKG abnormalities or dysrhythmia and with normal cardiac enzymes after 6 " 8 hr period may be discharged.
Issues for Referral
Immediate surgical consultation:

Suspected myocardial wall rupture
Suspected valve or papillary muscle rupture
Suspected septal rupture
Coronary artery thrombosis
Pericardial effusion
Cardiac tamponade

Followup Recommendations

Discharged patients:

Should have follow-up within 24 hr of injury

Pearls and Pitfalls

Obtain EKG in patients following chest wall trauma.
Perform FAST exam on all patients to assess pericardium.
External signs of chest wall trauma should increase concern of blunt cardiac injury.
Pediatric patients may have little or no external signs of chest wall trauma.
Do not administer thrombolytics to patients with ST elevation MI following trauma.
Negative troponin I and normal EKG make significant blunt cardiac injury unlikely.

Additional Reading

Clancy K, Velopulos C, Bilaniuk JW, et al. Screening for blunt cardiac injury: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012;73:S301 " S306.
El Chami MF, Nicholson W, Helmy T. Blunt cardiac trauma. J Emerg Med. 2008;127 " 133.
Rajan GP, Zellweger R. Cardiac troponin I as a predictor of arrhythmia and ventricular dysfunction in trauma patients with myocardial contusion. J Trauma. 2004;57:801 " 808.
Salim A, Velmahos GC, Jindal A, et al. Clinically significant blunt cardiac trauma: Role of serum troponin levels combined with electrocardiographic findings. J Trauma. 2001;50:237 " 243.
Sybrandy KC, Cramer MJ, Burgersdijk C. Diagnosing cardiac contusion: Old wisdom and new insights. Heart. 2003;89(5):485 " 489.

Codes

ICD9

861.01 Contusion of heart without mention of open wound into thorax

ICD10

S26.01XA Contusion of heart with hemopericardium, initial encounter
S26.11XA Contusion of heart without hemopericardium, init encntr
S26.91XA Contusion of heart, unsp w or w/o hemopericardium, init

SNOMED

17414004 Contusion to heart (disorder)

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