How many SA nodes do heart transplant patients have?

How many SA nodes do heart transplant patients have?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Heart transplant patients typically have two sinoatrial (SA) nodes. When a heart is transplanted, the donor heart comes with its own SA node, which is responsible for initiating the heartbeat. The recipient's body still has its original SA node, but it usually becomes non-functional and disregarded due to the surgical procedure and the loss of nervous system control over the transplanted heart. Thus, the presence of both the donor's SA node and the recipient's non-functional SA node leads to the conclusion that there are two SA nodes present post-transplantation. This unique situation highlights the complexities of heart transplantation and its effects on physiological cardiac function.