Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms (arrhythmias) usually caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a variant of sick sinus syndrome in which the arrhythmia alternates between fast and slow heart rates.
Signs and symptoms
Often sinus node dysfunction produces no symptoms, especially early in the disease course. Signs and symptoms usually appear in more advanced disease and more than 50% of patients will present with syncope or transient near-fainting spells as well as bradycardias that are accompanied by rapid heart rhythms, referred to as tachycardia-bradycardia syndrome Other presenting signs or symptoms can include confusion, fatigue, palpitations, chest pain, shortness of breath, headache, and nausea. Patients can also present with symptoms of congestive heart failure, stroke or transient ischemic attacks due to the abnormal rhythm. Sinus node dysfunction has a close association with the presence of atrial fibrillation due to their shared etiology of remodeling. Sinus node dysfunction can also present with sudden sinus arrest with or without junctional escape, sinoatrial block, prolonged asystolic period followed by tachycardias, or tachycardia-bradycardia syndrome presenting as various atrial arrhythmias such as atrial fibrillation, flutter, tachycardia, or paroxysmal supraventricular tachycardia. The goal of this treatment modality is to relieve symptoms associated with sinus node dysfunction and improve quality of life.
In tachycardia-bradycardia syndrome, medication-based management can treat atrial tachyarrhythmias. However, these medications may exacerbate underlying bradyarrhythmia. Therefore, a dual-chamber pacemaker capable of managing atrial tachyarrhythmias as well as bradyarrhythmias is implanted before drug therapy is begun. with 1 in 1000 in adults over 45 years old