Episode 952: Heart Transplants - podcast episode cover

Episode 952: Heart Transplants

Apr 14, 20253 min
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Summary

This episode discusses key clinical considerations for managing heart transplant patients. It covers topics such as arrhythmias (including the lack of vagal tone and response to medications like atropine and adenosine), rejection (both acute and chronic manifestations), the increased risk of infection due to immunosuppression, and radiographic cardiomegaly. The episode also highlights the importance of recognizing atypical symptoms in these patients due to denervation.

Episode description

Contributor: Travis Barlock, MD

Educational Pearls:

  • Key clinical considerations when managing heart transplant patients due to their unique pathophysiology

  • 1. Arrhythmias

    • A transplanted heart is denervated, meaning it lacks autonomic nervous system innervation

      • The lack of vagal tone results in an increased resting heart rate

      • Adenosine can be used since it primarily slows conduction through the AV node 

      • Atropine is ineffective in treating transplant bradyarrhythmia because its mechanism is to inhibit the vagus nerve - but the heart lacks vagal tone

    • Allograft rejection can also cause tachycardia

      • Consult transplant surgery - treatment is usually 500 mg methylprednisolone

  • 2. Rejection

    • Transplant patients are administered immunosuppressants

    • Clinical presentation of acute rejection looks similar to heart failure with increased BNP, increased troponin, and pulmonary edema 

    • Cardiac allograft vasculopathy is a form of chronic rejection

    • Patients will not report chest pain due to denervated heart

      • Symptoms are usually weakness and fatigue

  • 3. High risk of infection due to immunosuppression

    • Increased risk of infections which includes CMV, legionella, tuberculosis, etc

    • Immunosuppressants have side effects such as acute kidney injury or pancytopenia

  • 4. Radiographic Cardiomegaly

    • A study found that radiographic cardiomegaly does not connote heart failure

    • They hypothesized it is instead the result of a mismatch between the size of the transplanted heart and the space in the thoracic cavity 

References

  1. Murphy JD, Mergo PJ, Taylor HM, Fields R, Mills RM Jr. Significance of radiographic cardiomegaly in orthotopic heart transplant recipients. AJR Am J Roentgenol. 1998 Aug;171(2):371-4. doi: 10.2214/ajr.171.2.9694454. PMID: 9694454.

  2. Park MH, Starling RC, Ratliff NB, McCarthy PM, Smedira NS, Pelegrin D, Young JB. Oral steroid pulse without taper for the treatment of asymptomatic moderate cardiac allograft rejection. J Heart Lung Transplant. 1999 Dec;18(12):1224-7. doi: 10.1016/s1053-2498(99)00098-4. PMID: 10612382.

  3. Pethig K, Heublein B, Wahlers T, Dannenberg O, Oppelt P, Haverich A. Mycophenolate mofetil for secondary prevention of cardiac allograft vasculopathy: influence on inflammation and progression of intimal hyperplasia. J Heart Lung Transplant. 2004 Jan;23(1):61-6. doi: 10.1016/s1053-2498(03)00097-4. PMID: 14734128.

Summarized by Meg Joyce, MS1 | Edited by Meg Joyce & Jorge Chalit, OMS3

Donate: https://emergencymedicalminute.org/donate/

 

Transcript

This is the Emergency Medical Minute. Brought to you by HCA HealthONE. Today's medical minute is going to be on heart transplants. and some of the pearls to know about that. When you have a patient who comes in with a heart transplant, there's just a couple of important conditions to keep in mind and some nuances to their pathophysiology and presentation that I think are kind of interesting and something to think about. So one is going to be dysrhythmias.

When you get a heart transplant, you have to cut the vagus nerve and so they don't have any vagal tone. so they are kind of like always very often are gonna be tachycardic and that also means that they're gonna not have any response to atropine, but they're going to be fairly responsive to adenosine. Additionally, their tachycardias can be caused by allograft rejection and sometimes a push of 500 of methylprednisone.

can help abate that, but you do want to talk to transplant surgery about that if you can. Additionally, just overall rejection is the big thing we worry about, right? It's a foreign tissue. their immune system will attack it, and that's why we give them immunosuppressants. When that happens, they can go into something that just looks like heart failure.

So troponins would be bummed, BNPs would be elevated, looks like pulmonary edema, and they can also get coronary allograft vasculopathy. So that would kind of look like coronary artery disease. So that's just an interesting way it can kind of manifest.

and again this is the vagus nerve is cut they can't feel it so if you have a patient who's having a heart attack right the chest pain you know shortness of breath that's the typical complaint but when you're that nervous cut they don't have that sensation so their complaints are like really vague it's weakness it's fatigue they're not going to really complain of chest pain

which i think is kind of interesting infection right any patient who's on the chronic immune suppression is going to be at high risk for infection those patients are going to be most commonly getting those after the first few months of a transplant and they're also more at risk for some more obscure infections like CMV, legionella, tuberculosis, cryptococcus, those are all possible. And then medication side effect just from all their immunosuppressants.

So calcineurin inhibitors, mycophenylates, those things can cause AKIs and pancytopenia, respectively. So just some pearls about that. Lastly, also... a donor heart might not be the same size for their body so they might just have like a weird you know enlarged heart just because it was the a larger person that donated it to them and so

Yeah, always kind of interesting kind of features of it. This has been the Emergency Medical Minute. Thank you for listening, and thank you to HCA HealthOne for their financial contribution. Support from them and from listeners like you helps us achieve our goal of spreading free education to the masses. If you'd like to help, please donate, follow the link in our show notes. Thanks for listening.

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