Normal sinus rhythm (NSR) is the characteristic and healthy rhythm of the human heart originating from the heart's natural pacemaker, the sinus node.
Here's a more detailed breakdown:
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Origin: The electrical impulses that trigger each heartbeat originate in the sinoatrial (SA) node, also known as the sinus node. This node is located in the right atrium of the heart.
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Regularity: In NSR, the heart rate is generally regular, meaning the time between each heartbeat is consistent. However, slight variations are normal due to factors like breathing and autonomic nervous system activity.
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Rate: The normal heart rate range for an adult in NSR is typically between 60 and 100 beats per minute (bpm). This range can vary depending on age, fitness level, and other individual factors.
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Characteristics on ECG (Electrocardiogram): An ECG is used to visualize the electrical activity of the heart. In NSR, the ECG will show:
- A P wave preceding each QRS complex (indicating atrial depolarization originating from the sinus node).
- A consistent PR interval (the time it takes for the electrical impulse to travel from the atria to the ventricles).
- Normal QRS complex morphology (representing ventricular depolarization).
- A consistent P wave morphology.
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Influences: The heart rate in NSR is influenced by the autonomic nervous system. The sympathetic nervous system increases heart rate (e.g., during exercise or stress), while the parasympathetic nervous system decreases heart rate (e.g., during rest).
In summary, normal sinus rhythm indicates that the heart is beating regularly, at a normal rate, and the electrical impulses are originating from the correct location (the sinus node). It's a sign of a healthy heart.
