Sinus arrhythmias are changes in heart rhythm that become faster or slower. This condition is generally not dangerous and is not a sign of a serious disturbance in the heart. Sinus arrhythmias are closely related to sinus function which refers to a part of the heart called the sinoatrial node, which is a natural pacemaker that is located in the right ventricular wall of the heart. Sinus functions to control the rhythm of the human heart. Under normal conditions, the heart should have a stable sinus rhythm. Sinus Arrhythmias Rarely Symptoms Sinus arrhythmias are associated with the heart and respiratory system. A person's heart rhythm will increase when he breaths and will decrease when he sighs. Sinus arrhythmias can occur in the form of sinus bradycardia or heart rhythm that becomes slow, which is below 60 times per minute, and sinus tachycardia or fast heart rhythm, above 100 times per minute. The cause of sinus arrhythmia is still unknown. Most sufferers also rarely compl...