Sinus arrest is a condition where the heart’s primary pacemaker has problems with electrical impulses, causing the heart to stop beating. It can be caused by problems with the sinus node or heart’s conduction system. Symptoms include dizziness, unconsciousness, and cardiac arrest. Treatment involves an artificial pacemaker. Survival depends on overall heart health.
Sinus arrest is a condition in which the heart’s sinoatrial (SA) node, the heart’s primary pacemaker, has problems with the formation and propagation of electrical impulses. This results in the heart failing to beat. The condition is referred to as sinus pause if only one or two beats are missed, and sinus arrest if more than two beats are missed. Sinus arrest is a form of sinus node dysfunction (SND).
In a healthy heart, the cardiac cycle is produced by a cyclical flow of electricity through the heart. The sinus node sends an impulse through the atria, causing the muscles to contract and pumping blood into the ventricles. The impulse then reaches the atrioventricular (AV) node. After pausing to allow the ventricles to fill with blood, the AV node retransmits the impulse to the ventricles. The contracting ventricles then pump blood out of the heart and out to the rest of the body.
In sinus arrest, the cardiac cycle is interrupted and the heart stops beating. This will continue until the sinus node impulse is effectively restored or the atrioventricular node assumes the role of pacemaker. These missed beats can be clearly identified on an electrocardiogram (ECG) strip.
The causes of this failure are typically related to the formation or propagation of electrical impulses. There may be a problem with the sinus node, where impulse formation is the problem. There may also be problems with the heart’s conduction system, where the impulse isn’t being propagated properly. Conductive problems can result from natural deterioration, hypothyroidism, or electrolyte imbalances.
The effects of sinus arrest typically present as brain or heart symptoms. Brain symptoms include dizziness, slurred speech, unconsciousness, and syncope. The most serious of these symptoms is syncope, or loss of consciousness, caused by lack of blood flow to the brain. Cardiac symptoms include palpitations, angina, symptoms of congestive heart failure and, in severe cases, cardiac arrest. Minor incidents such as sinus pauses are often asymptomatic and can only be detected via an ECG.
Sinus arrest usually occurs in elderly patients, due to natural deterioration of the SA node, atrial muscle, and conductive system. This phase of sinus arrest is progressive in nature and irreversible. When sinus arrest occurs earlier in life, it is usually a complication of another heart problem or a severe electrolyte imbalance.
Typically, no treatment is required for asymptomatic patients. For chronic sinus arrest, treatment involves the use of an artificial pacemaker. Research has shown that sinus node dysfunction occurs in about one in 600 heart patients who are over the age of 65. Nearly half of these patients will develop tachy-brady syndrome at some point and face an increased risk of stroke and death.
Survival appears to depend on the patient’s overall heart health. A pacemaker will treat sinus arrest effectively, but won’t significantly change other underlying heart problems. In most cases, it is not sinus arrest that directly leads to death; rather, it’s a combination of other chronic heart problems.
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