What is sinus arrhythmia?
Sinus arrhythmia refers to a normal variation in the heart rhythm caused by breathing. It is not a true arrhythmia, in the sense that it is not a truly abnormal heart rhythm. In fact, in most cases sinus arrhythmia is actually a sign of a healthy, well functioning heart.
Normal electrical conduction in the heart involves transmission of electrical impulses from the sinus node in the top right corner of the heart, through the AV node in the middle of the heart, and into the ventricles below. As the electricity is transmitted to the heart, the ventricles contract.
What causes sinus arrhythmia?
The heart is positioned in the chest cavity, along with the lungs. Every time we breathe in, we created a negative pressure in our lungs which draws in air. When we breathe out, the opposite happens - a positive pressure is created. Since it sits in the chest with the lungs, the heart is also exposed to these pressure changes. With breathing in, a slightly negative pressure is created in the heart. This causes a slight increase in the volume of blood returning to the heart. The heart senses this slight increase in volume and interprets it as a sign that the heart is filling up. It therefore responds by beating slightly faster. The opposite happens during expiration, or breathing out. The heart slows down as it senses a slight decrease in volume. These minor changes in the heart rate that can happen momentarily are termed sinus arrhythmia. They are a normal and expected finding simply caused by normal breathing.
How is sinus arrhythmia diagnosed?
Occasionally sinus arrhythmia may be mistaken for something more concerning, for example a true arrhythmia, such as premature atrial contractions or premature ventricular contractions. Usually a well-trained ear can differentiate the cause, although occasionally an ECG or Holter monitoring may be necessary.
Does sinus arrhythmia require treatment?
Since sinus arrhythmia is a normal finding, it does not require any special treatment, precautions, or restrictions.