Pathophysiology Sick Sinus Syndrome

According to "Current Medical Diagnosis and Treatment, 2010," sick sinus syndrome describes dysfunction of the intrinsic pacemaker of the heart, the sinoatrial node. As a result, the heart rhythm becomes abnormal and characterized by intermittent tachyarrythmias (fast heart rhythms) and bradyarrythmias (slow heart rhythms).

Normal Sinoatrial Node

• The book, "Harrison's Principles of Internal Medicine" says, that the electrical impulse that causes the heart to beat originates within the specialized cluster of cells known as the sinoatrial node or sinus node. The electricity is then conducted to other parts of the heart eventually resulting in contraction of the muscular portions, and ejection of blood to the lungs and other parts of the body.

Causes

• "Current Diagnosis and Treatment in Cardiology" says that sick sinus syndrome can occur due to degeneration of the sinus node, disruption of blood flow to parts of the heart or as a result of certain medications including beta-blockers, diltiazen, verpamil, digitalis, class I and II antiarrhythmics and clonidine.

Symptoms

• Most individuals with sick sinus syndrome have no symptoms. However, some may experience dizziness, confusion, palpitations, heart failure and chest pain.

Diagnosis

• A diagnosis of sick sinus syndrome can be identified by abnormal electrical activity of the heart detected with electrocardiogram (ECG). Continuous monitoring with a Holter monitor often proves an effective means of diagnosis, says the book, "Current Medical Diagnosis and Treatment."

Treatment

• Treatment is generally initiated for those who have symptoms. Therapy may include medications or temporary pacing of the heart. Many symptomatic patients will require placement of a permanent pacemaker.