The longest r-r interval is the longest time between two heartbeats. 1. If the interval between r-r intervals is >5s, it means that the heart does not beat within 5s, and ischemia of the heart, brain, kidneys and other vital organs may occur at this time, and the situation is very serious. We should look for the specific cause in time, clarify whether it is caused by drugs, poison or conduction system lesions, etc., and carry out treatment according to the cause of the disease. 2. If it is a conduction system lesion, a pacemaker needs to be implanted. If the r-r interval is 3 to 5 s, the patient should be observed to see if there is ischemia of vital organs caused by slow heartbeat, and if there is ischemia, pacemaker implantation is also needed. 3. If the r-r interval is <3s, the risk is relatively small. The normal r-r interval should be between 0.6 and 1.0 s. Less than 0.6 s indicates tachycardia and more than 1.0 s indicates bradycardia. When performing a 24-hour ambulatory electrocardiogram, it is important to focus not only on the average heart rate, but also on the slowest heart rate, the longest r-r interval, etc., as well as whether or not the r-r interval is causing the patient's associated symptoms.