Blunt Cardiac Trauma
Usually from MVC from hitting steering wheel. Spectrum of concussion to contusion to infarction to rupture.
Myocardial concussion: also known as commotio cordis. Second MCC sudden death in athletes after HOCM. No structural heart disease on autopsies. Impact causes primarily electrical event causing ventricular fibrillation. Treatment includes bystander CPR and defibrillation. Need monitoring afterward with likely outpatient stress test, cardiac MRI, obviously no sports until cleared by cardiology.
Myocardial contusion: usually associated with other thoracic trauma (rib fractures, pulmonary contusions, etc). Most common sign: sinus tachycardia. Sometimes cardiogenic shock. Right ventricle most commonly affected due to it is the most anterior portion of the heart. New EKG abnormality usually means admission for observation and monitoring. Trop best biomarker. If negative EKG and biomarker, low suspicion for contusion. Consider pericarditis later on 2-3 weeks later with chest pain, fever and chest wall blunt injury.
Myocardial rupture: almost always fatal. Right ventricle most commonly affected. usually patients survive long enough to the ED have intact pericardium with tamponade. Murmur harsh sounding, bruit de moulin – splashing-mill wheel – ‘pneumopericardium.’ Use ultrasound for diagnosis and will need emergent thoracotomy. CXR not great. Pericardiocentesis is usually only temporizing at best. If thoracotomy done, treatment with finger occlusion, foley, or staples.
Penetrating Cardiac Trauma
If survive to hospital, 80% mortality. Right ventricle most commonly injuries (43%), then left ventricle (34%), then atria after this. 5% have coronary artery involved. Either exsanguination usually from GSW and usually dead on scene vs pericardial tamponade most commonly seen with stab needing emergent thoracotomy.
Indications for emergent thoracotomy: cardiac arrest with initial signs of life or SBP < 50 after resuscitation in penetrating injury; cardiac arrest in the ED with blunt trauma.
Pericardial tamponade: stab > GSW, RV stab tend to seal themselves as well. Diagnosis with rapid ultrasound. Beck’s triad:distended neck veins, hypotension, distant heart sounds. Usually tachycardia first, then hypotension. EKG shows electrical alternans classically though this is usually only seen on chronic pericardial effusion. Pericardicentesis can be done and sometimes only 5-10mL of blood can drastically improve stroke volume temporarily. usually clotted blood though.
Thoracotomy: Left lateral incision in same area of chest tube (5th intercostal space at nipple/inframammary line) and extend to sternum. Can extend to right side with clam-shell technique going through sternum if considering right sided laceration if left side doesn’t show much. Excise pericardium anterior to phrenic nerve in vertical incision. Deliver heart from pericardium. If hole, use digital for pressure or foley or standard skin staples.
Blunt Aortic Injury
Usually due to sudden decal. Most common sites are aortic isthmus (just distal to left subclavian artery where aorta attached to ligament arteriosium) and proximal ascending aorta. CXR will show widened mediastinum (width > 8cm or mediastinum/chest width radio > 0.38) though not specific or sensitive. CT chest is preferred imaging. Careful regulation of BP and HR due to sheering forces – treat like medical aortic dissection. Treatment likely with synthetic graft endovascularly – may need vascular surgeon or IR rather than CT surgery. Complications after stunting can be later on dissection.
Q. Whats the most common site for blunt aortic injury?
A. Aorta isthmus. Wrong answers: Ascending aorta, distal descending aorta, site of coronary artery insertion
Q. Whats the most common EKG finding with myocardial contusion?
A. Sinus tachycardia. Wrong answers: PVCs, LBBB, RBBB, ventricular fibrillation.
Rosens, Second Edition, Chapter 38: Thoracic Trauma
Tintinalli, Seventh Edition, Chapter 258: Cardiac Trauma
What’s New in Trauma, William Mallon, AAEM Scientific Assembly 2017