August 1, 2012 by EmerJencyWEBB
It is that time again. Like I said before, I’m prepping a senior lecture on Cardiac Trauma to be delivered later this month. We’ll start with the basics here by outlining the awesome chapter in the 7th Edition, which if you haven’t flipped through yet, get your hands on one. Great images and tables, new chapters, and also an additional DVD with even more goodies. In the next few weeks, we’ll add more to this topic with additional multimedia, procedure guidelines, and journal articles with the most recent information about the topic. So let’s get to it!
Pearl: Know the anatomical landmarks and boundaries that may constitute a thoracic injury, especially in penetrating trauma. The diaphragm, for example, is a moving target, so an injury that on first glance looks epigastric, may have actually gone intrathoracic. Also surface injury does not correspond to missle trajectory. Cardiac Box: area between sternal notch and xiphoid process, bounded laterally by nipples
- In order of injury prevalence: RV > LV > RA > LA
- It makes sense that anterior structures are more commonly injured.
- However, remember that no structure of the heart is off limits for injury including valves and coronaries
- Stab wounds tend to involve less structures, do less damage, and these pts are more likely to survive to hospital discharge
- The primary causes of death including bleeding out (less likely in isolated RV injuries as muscular wall may seal itself) and suffering tamponade
- Cardiac Tamponade: more common with smaller pericardial wounds (more likely to seal off)
- As little as 65cc of fluid can increase intrapericardial pressure and begin to decrease LV filling and CO
- Beck’s Triad and Pulsus Paradoxus are classic signs, but may not be apparent on initial eval
Blunt Cardiac Trauma
- Reportedly up to 20% of MVC deaths can be attributed to blunt cardiac injury
- Again, right heart (more anterior) structures are most susceptible to trauma
- Mechanisms of death: arrythmia, wall/septal/papillary rupture, coronary damage
- Minor injuries are usually reversible within 24 hrs.
- Special Case: Commotio Cordis – results fromdirect blow to chest (may look like a fairly benign injury to bystanders until the patient drops dead). Mechanism usually R on T phenomenon to send heart into V fib.
- If new murmur, suspect valvular, septal, or papillary muscle injury (think about causes of mumur in non-traumatic patients)
- Most common coronary artery injured is LAD (bad juju)
- Post traumatic pericarditis has also been reported as delayed sequelae (correlate with post-MI pericarditis)
- Cardiac chambers most susceptible to rupture: atria (thin walls) – listen close, you may hear the “Bruit de Moulin“
- A normal ECG does not exclude a clinically significant cardiac injury.
- Troponins may be elevated in all forms of cardiac injury, but if clinically significant, are usually accompanied by ECG changes
- The best radiographic modality is echocardiogram, with TEE winning out over TTE for sensitivity (however, use what is available). And remember your FAST exam to answer the question “Is there fluid around the heart?”. Especially in the setting of penetrating injury, treat this as operative emergency.
How to Treat
- All will require operative intervention. In the HD unstable pt, or those that arrested in the field or in the ED with prior signs of life, ED Thoracotomy is indicated. Pericardiocentesis may also be a life-saving maneuver, but the extent to which it helps is limited by the clotting of blood in pericardium as well as the lack to expose/fix underlying injury. However, it has been reported that very small volumes (5-10cc) may improve CO dramatically.
Blunt Cardiac Injuries
- Observe if suspicion is high, and eval for structural complications.
NOT COVERED IN THIS OUTLINE: GREAT VESSEL INJURY DIAGNOSIS/MANAGEMENT, DETAILS ON CARDIAC PROCEDURES, MUCH MORE
(This outline is only a reference, and is not all-inclusive of ideas presented in the published chapter. Please refer to the definitive text for details beyond the big ideas above. All credit to the written material above goes to Tintinalli’s Emergency Medicine: A Comprehensive Study Guide 7th Edition)