Ep 155: An 18-Year-Old with Trauma to the Chest

In this episode, we review the differential diagnosis of cardiac injuries.

Read more on this topic in Harrison's.

Harrison's Principles of Internal Medicine, 22nd Edition

Transcript

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[Ms. Heidhausen] This is Katerina Heidhausen, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. 

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[Dr. Handy] Hi, everyone. Welcome back to Harrison's PodClass. We're your co-hosts. I'm Dr. Cathy Handy. 

[Dr. Wiener] And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. 

[Dr. Handy] Welcome back to today's episode: an 18-year-old with trauma to the chest. 

[Dr. Wiener] Cathy, today's case is topical, especially for those of us that are sports fans. 

[Dr. Handy] And who is not? 

[Dr. Wiener] I don't know, but here it goes. You are volunteering as a medical professional at a high school lacrosse game. During the game, one of the defenders steps in front of a shot that hits him in the chest. Seconds later, he falls to the ground and is unresponsive. 

[Dr. Handy] Oh dear. I know that that happened within the past few years here in the mid-Atlantic region, and it sounds similar to what had happened with Damar Hamlin of the Buffalo Bills. 

[Dr. Wiener] Exactly. So the question is asking, which of the following is the most likely mechanism of this injury? And the options are A. aortic transection; B. mitral valve rupture; C. myocardial rupture; D. Takotsubo syndrome; or E. ventricular fibrillation. 

[Dr. Handy] All right, in general, what we are talking about is blunt cardiac injury or non-penetrating trauma. Blunt cardiac injuries most often occur during motor vehicle accidents, actually, and that's either from rapid deceleration or from the impact of the chest against the steering wheel or airbag. Importantly, rapid deceleration following motor vehicle accidents may be associated with significant cardiac injury even in the absence of external signs of thoracic trauma. 

[Dr. Wiener] Okay, so our case today is a little bit less common. Other lesser common types of cardiac trauma? Where do they occur? 

[Dr. Handy] It's very rare for it to happen during sports, but it is possible. Blunt cardiac injury can also result from falls from heights, or crush injuries, or blast injuries, or even from assault. 

[Dr. Wiener] Is this the same as a myocardial contusion? 

[Dr. Handy] Myocardial contusion is a non-specific term, but it's been used to describe a broad spectrum of non-penetrating cardiac injuries that result in abnormalities that are found on EKG with an elevation of cardiac biomarkers and acute structural cardiac abnormalities. There is no single sign, symptom, or test that confirms a diagnosis of blunt cardiac injury. 

[Dr. Wiener] What about physical exam? 

[Dr. Handy] The physical examination may be challenging in the setting of chest wall injury. However, patients should be carefully examined to detect pericardial rubs, cardiac murmurs, and evidence of pericardial tamponade. There is no proven association between sternal or rib fractures and the presence of blunt cardiac injury, and significant cardiac injury may be present in the absence of chest wall abnormalities. 

[Dr. Wiener] You already mentioned ECG and cardiac biomarkers. How do they figure in? 

[Dr. Handy] The injured myocardium is pathologically similar to infarcted myocardium, and it may be associated with atrial or ventricular arrhythmias, or conduction disturbances, or abnormalities on ECG resembling those of infarction or pericarditis. Serum CK-MB isoenzymes are increased in about 20% of patients who experience blunt chest trauma, but they may be falsely elevated in the presence of massive skeletal muscle injury and should not be relied upon to confirm the diagnosis of blunt cardiac injury in the setting of trauma. Cardiac troponin levels are more specific for identifying cardiac damage. Patients with normal serial troponin levels after chest trauma are very unlikely to have cardiac injury. When combined with a normal ECG, a normal troponin level at six to eight hours after chest trauma essentially excludes blunt cardiac injury. 

[Dr. Wiener] How about using an echocardiogram? That's often included in our POCUS exams. 

[Dr. Handy] Yes, that's the most useful test in suspected blunt cardiac injury as it may detect structural and functional abnormalities. A transthoracic echocardiogram should be performed in all patients with suspected blunt cardiac injury, especially in those with an abnormal ECG, elevated troponin, or hemodynamic instability. 

[Dr. Wiener] Okay, well, let's get to our question. What is going on with our young lacrosse player? 

[Dr. Handy] Well, first is to say that all the options may occur after blunt cardiac trauma, but this is most likely a case of so-called commotio cordis or agitation of the heart. That's been described in a variety of sporting events including lacrosse, football, baseball, hockey. And as I mentioned earlier, there was the highly public event in 2023 during a Monday night football game when Damar Hamlin had sudden death after a football play. 

[Dr. Wiener] So, the answer is E. ventricular fibrillation? 

[Dr. Handy] Yes, and immediate cardioversion can be lifesaving, and that's why it is vital to have defibrillators handy at sporting events where blunt cardiac trauma is possible. 

[Dr. Wiener] Before we finish, you mentioned that all the others are possible. Let's quickly go over them. 

[Dr. Wiener] Rupture or transection of the aorta is the most common vascular deceleration injury. It usually occurs just above the aortic valve or at the site of the ligamentum arteriosum. The clinical presentation may be similar to aortic dissection. Mitral or tricuspid valve rupture will present with acute regurgitation. And Takotsubo syndrome is an acute catecholamine-mediated cardiomyopathy that may present after not only blunt cardiac injury, but also any emotional or physical trauma. 

[Dr. Wiener] And myocardial rupture? 

[Dr. Handy] Myocardial rupture is the most serious consequence of non-penetrating cardiac injury and it may result in hemopericardium and tamponade or intracardiac shunting depending on the location of the injury. Although generally fatal, up to 40% of patients with cardiac rupture have been reported to survive long enough to reach a specialized trauma center. And inflammatory pericarditis or pericardial effusion, resembling post-pericardiotomy syndrome may develop weeks or even months after blunt cardiac injury. 

[Dr. Wiener] Great, so the teaching points today are that blunt cardiac injury may occur from a variety of mechanisms and may present with structural or functional manifestations. Commotio cordis and ventricular fibrillation may result from blunt cardiac injury. Cardioversion may be lifesaving in these cases. 

[Dr. Handy] And you can find this question and other questions like it in the Harrison's Self-Review. And to read more about this topic, check out the chapter on cardiac trauma. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on AccessMedicine. If you enjoyed this episode, please leave us a review, so we can reach more listeners just like you. Thanks so much for listening. 

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