Cardiology MCQ 219: Intrinsic heart rate

Intrinsic heart rate is:

a. Normal heart rate
b. Heart rate after total sympathetic blockade
c. Heart rate after total sympathetic and parasympathetic blockade
d. Heart rate after total para sympathetic blockade


[“Click here for the answer with explanation”, “Correct Answer:”]

c. Heart rate after total sympathetic and parasympathetic blockade

Intrinsic heart rate (IHR) is measured after total autonomic blockade with a combination of propranolol and atropine. It indicates the basic rhythmicity of the sinoatrial node without any autonomic influence. It is calculated by the formula:

IHR = 117.2 – (0.53 x age) beats/min