What causes normal sinus rhythm?

As a cardiac electrophysiologist, I specialize in the study of the heart's electrical activity and how it affects the heart's rhythm. Here's a detailed explanation of what causes normal sinus rhythm (NSR): Normal sinus rhythm (NSR) is the natural rhythm of the healthy human heart. It is a regular and organized pattern of electrical impulses that initiates with the sinus node, which is often referred to as the heart's natural pacemaker. The sinus node is located in the upper part of the right atrium and is responsible for setting the heart's baseline rhythm. The rhythm that originates from the sinus node is characterized by a regular sequence of electrical signals that travel through the heart muscle, causing the atria to contract and then the ventricles. This coordinated contraction ensures efficient blood circulation throughout the body. The rate of NSR is typically regular, with a heart rate ranging from 60 to 100 beats per minute (bpm) for adults at rest. However, this rate can vary depending on several factors, including age, physical fitness, and health status. For example, well-trained athletes may have a lower resting heart rate, while children and adolescents typically have a higher resting heart rate. The NSR rate will also fluctuate based on autonomic inputs into the sinus node. The autonomic nervous system, which includes the sympathetic and parasympathetic divisions, plays a critical role in regulating heart rate. The sympathetic division can increase the heart rate, while the parasympathetic division can decrease it. In summary, normal sinus rhythm is caused by the regular electrical activity originating from the sinus node, which is influenced by the autonomic nervous system to respond to the body's needs.

Normal sinus rhythm (NSR) is the characteristic rhythm of the healthy human heart. NSR is the rhythm that originates from the sinus node. The rate in NSR is generally regular but will vary depending on autonomic inputs into the sinus node.