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

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

Increased risk of infections which includes CMV, legionella, tuberculosis, etc
Immunosuppressants have side effects such as acute kidney injury or pancytopenia

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

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.
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.
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

Episode 952: Heart Transplants

Emergency Medical Minute