The concept of a denervated heart is a significant consideration in patients receiving orthotopic heart transplants. When these donor hearts are procured, there’s no way to preserve native autonomic regulation (ie, vagal input). After transplantation, it can take many months/years before some semblance of autonomic regulation is reestablished. We can also see a similar pattern in patients with autonomic neuropathy due to end-stage diabetes.
When we wean off cardiopulmonary bypass after a heart transplant, it’s important to start some sort of direct acting adrenergic agent like dobutamine or epinephrine coupled with epicardial pacing to maintain an adequate cardiac output. Of note, the Frank-Starling law is an instrinsic property of the myocardium independent of autonomic input. Optimizing preload for these patients to carefully balance acute right heart overloading with sufficient forward flow is often times difficult. I use TEE, bedside TTE, and monitors like PA catheters to help determine the appropriate interventions at the right time: diuresis, increasing inotropy, weaning vasopressors, administering volume, vasodilation, etc.
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