What is Sinus Arrhythmia?
What is sinus arrhythmia? Heartbeats are like clockwork. In the same way the second hand on a clock ticks regularly each second, the heart has an electrical impulse that is generated and leads to a heartbeat in a regular manner. The timing between each of these generated impulses is known as the P-P interval.
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Most individuals have a minor variation in the P-P interval. Usually however this is small, <0.16 seconds. In individuals with sinus arrhythmia however, the P-P interval may vary by > 0.16 seconds.
Is Sinus Arrhythmia Normal?
There are typically 2 types of sinus arrhythmia. By far the most common is basically benign and known as respiratory sinus arrhythmia. Here the variation in the heart rate is related to the breathing cycle. The rate increases when the person breathes in and decreases when the person breathes out. Its what we call a physiological response and isn’t considered a significant abnormality. Its much more common in children and tends to decrease with age. The cause isn’t exactly known, but is thought related to reflexes related to the pulmonary and the vascular systems. As you can imagine, the sinus arrhythmia may be more pronounced in very heavy breathers, such as people with sleep apnea.
The other form of sinus arrhythmia is less common and known as non-respiratory sinus arrhythmia. It is more common in the elderly where it may occur in association with heart disease. Once again the exact cause is unknown.
Sinus arrhythmia is most commonly seen when the heart rate is slow. And when the heart rate speeds up, during exercise for example, the rhythm tends to become regular. In general, the presence of sinus arrhythmia is not indicative of the need for further testing and people can be reassured as to its generally benign nature.
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