From the Guidelines
Tachybrady syndrome, also known as sick sinus syndrome, is a cardiac condition where the heart's natural pacemaker (sinus node) malfunctions, causing alternating episodes of abnormally fast (tachycardia) and slow (bradycardia) heart rhythms. This disorder typically affects older adults and can cause symptoms such as fatigue, dizziness, fainting, shortness of breath, and chest pain. The condition occurs when the sinus node develops scarring or other damage that disrupts its normal electrical activity. Common causes include age-related fibrosis, heart disease, medications, and electrolyte imbalances. Diagnosis usually involves ECG monitoring, Holter monitors, or event recorders to capture the irregular rhythms. Treatment depends on severity but often requires permanent pacemaker implantation to regulate the heart rate, as stated in the guidelines by 1. Some patients may also need medications to control the tachycardia component, such as beta-blockers or calcium channel blockers. The condition is progressive, and without treatment, it can lead to complications like heart failure, stroke, or sudden cardiac arrest due to prolonged pauses between heartbeats.
Key Points
- Tachybrady syndrome is a cardiac condition that affects the heart's natural pacemaker, causing irregular heart rhythms.
- The condition typically affects older adults and can cause symptoms such as fatigue, dizziness, and fainting.
- Diagnosis involves ECG monitoring, Holter monitors, or event recorders to capture the irregular rhythms.
- Treatment often requires permanent pacemaker implantation to regulate the heart rate, as recommended by 1.
- Medications such as beta-blockers or calcium channel blockers may be needed to control the tachycardia component.
Treatment Considerations
- Permanent pacemaker implantation is the most effective treatment for symptomatic bradycardia, as stated in the guidelines by 1.
- The decision to implant a pacemaker for SND is often accompanied by uncertainty that arises from incomplete linkage between sporadic symptoms and ECG evidence of coexisting bradycardia.
- It is crucial to distinguish between physiological bradycardia due to autonomic conditions or training effects and circumstantially inappropriate bradycardia that requires permanent cardiac pacing, as noted in 1.
From the Research
Definition of Tachybrady Syndrome
- Tachybrady syndrome, also known as tachycardia-bradycardia syndrome (TBS), is a complication of sick sinus syndrome (SSS) characterized by alternating tachycardia and bradycardia 2, 3, 4, 5.
- It is a collection of disorders marked by the heart's inability to perform its pacemaking function, resulting in various arrhythmias, including bradyarrhythmias with or without accompanying tachyarrhythmias 4.
Electrophysiological Mechanisms
- The electrophysiological mechanisms of TBS involve dysfunction of ion channels responsible for initiation or conduction of cardiac action potentials, which may underlie both bradycardia and tachycardia 2.
- Bradycardia can also increase the risk of tachycardia, and vice versa, due to the complex relationship between ion channel dysfunction, tachycardia, and bradycardia in TBS 2.
Clinical Manifestations
- TBS can manifest with diverse symptoms, including palpitations, fatigue, lightheadedness, presyncope, and syncope, due to abnormal heart rhythms limiting tissue perfusion 3, 4.
- Cerebral hypoperfusion is most common, with syncope or near-fainting occurring in about one-half of patients 4.
Diagnosis and Treatment
- Diagnosis of TBS is made by electrocardiographic identification of the arrhythmia in conjunction with the presence of symptoms, and may involve inpatient telemetry monitoring, outpatient Holter monitoring, event monitoring, or loop monitoring 4.
- Treatment of TBS includes removing extrinsic factors, when possible, and pacemaker placement, which can decrease symptoms and improve quality of life, although it does not reduce mortality 4, 5, 6.