Episode 26 – Blunt Cardiac Injury: Emergency Department Diagnosis and Management (Trauma CME)

Show Notes Jeff: Welcome back to EMplify, the podcast corollary to EB Medicine’s Emergency Medicine Practice. I’m Jeff Nusbaum, and I’m back with my co-host, Nachi Gupta. This month, after a few months of primarily medical topics, we’re talking trauma, specifically Blunt Cardiac Injury: Emergency Department Diagnosis and Management. Nachi: With no gold standard diagnostic test and with complications ranging from simple ectopic beats to fulminant cardiac failure and death, this isn’t an episode you’ll want to miss. Jeff: Before we begin, let me give a quick shout out to our incredible group of authors from New York -- Dr. Eric Morley, Dr. Bryan English, and Dr. David Cohen of Stony Brook Medicine and Dr. William Paolo, residency program director at SUNY Upstate. I should also mention their peer reviewers Drs. Jennifer Maccagnano and Ashley Norse of the NY institute of technology college of osteopathic medicine and UF Health Jacksonville, respectively. Nachi: This month’s team parsed through roughly 1200 articles as well as guidelines from the eastern association for surgery in trauma also known as EAST. Jeff: Clearly a large undertaking for a difficult topic to come up with solid evidence based recommendations. Nachi: For sure. Let’s begin with some epidemiology, which is admittedly quite difficult without universally accepted diagnostic criteria. Jeff: As you likely know, despite advances in motor vehicle safety, trauma remains a leading cause of death for young adults. In the US alone, each year, there are about 900,000 cases of cardiac injury secondary to trauma. Most of these occur in the setting of vehicular trauma. Nachi: And keep in mind, that those injuries don’t occur in isolation as 70-80% of patients with blunt cardiac injury sustain other injuries. This idea of concomitant trauma will be a major theme in today’s episode. Jeff: It certainly will. But before we get there, we have some more definitions to review - cardiac concussion and contusion, both of which were defined in a 1989 study. In this study, cardiac concussion was defined as an elevated CKMB with a normal echo, while a cardiac contusion was defined as an elevated CKMB and abnormal echo. Nachi: Much to my surprise, though, abnormal echo and elevated ck-mb have not been shown to be predictive of adverse outcomes, but conduction abnormalities on ekgs have been predictive of development of serious dysrhythmia Jeff: More on complications in a bit, but first, returning to the idea of concomitant injuries, in one autopsy study of nearly 1600 patients with blunt trauma - cardiac injuries were reported in 11.9% of cases and contributed to the death of 45.2% of those patients. Nachi: Looking more broadly at the data, according to one retrospective review, blunt cardiac injury may carry a mortality of up to 44%. Jeff: That’s scary high, though I guess not terribly surprising, given that we are discussing heart injuries due to major trauma... Nachi: The force may be direct or indirect, involve rapid deceleration, be bidirectional, compressive, concussive, or even involve a combination of these. In general, the right ventricle is the most frequently injured area due to the proximity to the chest wall. Jeff: Perfect, so that's enough background, let’s talk differential. As you likely expected, the differential is broad and includes cardiovascular injuries, pulmonary injuries, and other mediastinal injuries like pneumomediastinum and esophageal injuries. Nachi: Among the most devastating injuries on the differential is cardiac wall rupture, which not surprisingly has an extremely high mortality rate. In terms of location of rupture, both ventricles are far more likely to rupture than the atria with the right atria being more likely to rupture than the left atria. Atrial ruptures are more survivable, whereas complete free wall rupture is nearly universally fatal. Jeff: Septal injuries are also on the ddx. Septal injuries occur immediately, either from direct impact or when the heart becomes compressed between the sternum and the spine. Delayed rupture can occur secondary to an inflammatory reaction. This is more likely in patients with a prior healed or repaired septal defects. Nachi: Valvular injuries, like septal injuries, are rare. Left sided valvular damage is more common and carries a higher mortality risk. In order, the aortic valve is more commonly injured followed by the mitral valve then tricuspid valve, and finally the pulmonic valve. Remember that valvular damage can be due to papillary muscle rupture or damage to the chordae tendineae. Consider valvular injury in any patient who appears to be in cardiogenic shock, has hypotension without obvious hemorrhage, or has pulmonary edema. Jeff: Next on the ddx are coronary artery injuries, which include lacerations, dissections, aneurysms, thrombosis, and even MI secondary to increased sympathetic activity and platelet activity after trauma. In one review, dissection was the most commonly uncovered pathology, occurring 71% of the time, followed by thrombosis, which occured only 7% of the time. The LAD is the most commonly injured artery followed by the RCA. Nachi: Pericardial injury, including pericarditis, effusion, tamponade, and rarely rupture, is also certainly on the differential. Jeff: In terms of dysrhythmias, sinus tachycardia is the most common dysrhythmia, with other rhythms, including PVC / PAC / and afib being found only 1-6% of the time. Nachi: And while conduction blocks are rare, a RBBB is the most commonly noted, followed by a 1st degree AVB. Jeff: Though also rare, commotio cordis deserves it’s own section as its the second most common cause of death in athletes < 18 who are victims of blunt trauma. Though only studied in swine models, it’s hypothesized that the impact to the chest wall during T-wave upstroke can precipitate v-fib. Nachi: Aortic root injuries usually occur at the insertion of the ligamentum arteriosum and isthmus. Such injuries typically result in aortic insufficiency. Jeff: And the last pathology on the differential requiring special attention is a myocardial contusion. Again, no standard definition exists, with some diagnostic criteria including simply chest pain and increasing cardiac enzymes, and others including cardiac dysfunction, ecg abnormalities, wall motion abnormalities, and an elevation of cardiac enzymes. Nachi: Certainly a pretty broad differential… before moving on to the work up, Jeff why don’t you get us started with prehospital care? Jeff: Prehospital management should focus on rapid identification and stabilization of life threatening injuries with expeditious transport as longer prehospital times have been associated with increased mortality in trauma. Immediate transport to a Level I trauma center should be the highest priority for those with suspected blunt cardiac injury. Nachi: In terms of who specifically should be transporting the patient, a Cochrane review evaluated the utility of ALS vs BLS transport in trauma. There is reasonably good data to support BLS over ALS, even when controlling for trauma severity. Moreover, when airway management is needed, advanced airway techniques by ALS crews were associated with decreased odds of survival. Regardless of who is there, the message is the same: focus not on interventions, but instead on rapid transport. Jeff: And if it does happen to be an ALS transport crew, without delaying transport, pain management with fentanyl is both safe and reasonable and preferred over morphine. Post opiate hypotension in prehospital trauma patients is a rare but documented complication. Nachi: And if the prehospital team is lucky enough, or maybe unlucky enough, i don’t know, to have a credentialed provider who can perform ultrasound for those suspected of having a blunt cardiac injury, the general prehospital data on ultrasound is sparse. As of now, it’s difficult to conclude if prehospital US improves care for trauma patients. Jeff: Interestingly, the system I work in has prehospital physicians, who do carry US, but I can’t think of a major trauma where ultrasound changed any of the decisions we made. Nachi: Right, and I think that just reinforces the main point here: there may be a role, we just don’t have the data to support it at this time. Jeff: Great, let’s move onto ED care, beginning with the H&P. Nachi: On history, make sure to elucidate if there is any chest pain, and if it’s onset was before or after the traumatic event. In addition, make sure to ask about dyspnea, fatigue, palpitations, and lightheadedness. Jeff: And don’t forget to get the crash details from the EMS crew before they depart! As a side note, for anyone taking oral boards in a few months, don’t forget to ask the EMS crew for the details!!! Nachi: A definite must for oral boards and for your clinical practice. Jeff: In terms of the physical, tachycardia is the most common abnormality in blunt cardiac injury. In those with severe injury, you may note refractory hypotension secondary to cardiogenic shock. But don’t be reassured by normal vitals, especially in the young, who may be compensating well despite being quite ill. Nachi: Fully undress the patient to appropriately inspect and percuss the chest wall - looking for signs of previous cardiac surgeries or pacemaker placement, as well as to auscultate for new murmurs which may be a sign of valvular injury. Jeff: Similarly, as concomitant injuries are common, inspect the abdomen, looking for ecchymosi...