Question

After a heart transplant, there is no nerve connection. What happens to heart rate with increased activity?

Answer 1

Heart transplant is a major operation worldwide.

If there is no nerve supply post surgery it is called as Cardiac Denervation.

This causes disappearance of neral input to Sinoatrial node leading to loss of afferent and efferent nerve signals in and out of the heart

.This leads to further loss of sensation if the patient has a angina attack due to ischemia.

Furthere this leads to loss of Ventricular sensory input finally leading to Hypotension (low Blood Pressure) and Bradycardia (decreased heart rate). This is because of inferior wall ischemia.

Then causing loss of presynaptic neuronal uptake directly affecting the catecholamine actions by its superaction.

The exercise capacity is decreased ,hence catecholamines are released to adapt to the exercise.Although this is not sufficient to bring the normal heart rate but increases slowly due to exercises and decends down post exercise than the normal level when compared to a healthy individuals.

Hence the heart rate before exercise is on the low level ,then increases to an extent during exercise and then coming back to the same level

In addition to this cardiac output is altered during and and after exerise

Therefore cardiac degeneration leads to poor cardiovascular control in the heart transplant recipient.