Summary about Disease
Inappropriate Sinus Tachycardia (IST) is a heart condition characterized by an abnormally high resting heart rate (usually over 100 beats per minute) that is not caused by typical physiological factors like exercise, stress, fever, or underlying medical conditions. It is considered "inappropriate" because the heart rate is elevated beyond what is expected for the person's activity level and circumstances. The underlying mechanism is not completely understood, but it is thought to involve dysfunction in the sinus node (the heart's natural pacemaker) or in the autonomic nervous system's control of heart rate.
Symptoms
Common symptoms include:
Rapid heartbeat or palpitations
Dizziness or lightheadedness
Shortness of breath
Chest pain or discomfort
Fatigue
Anxiety
Sweating
Exercise intolerance (feeling unusually tired with minimal exertion)
Causes
The exact cause of Inappropriate Sinus Tachycardia is often unknown (idiopathic). However, potential contributing factors may include:
Sinus node dysfunction
Autonomic nervous system imbalance (increased sympathetic or decreased parasympathetic activity)
Increased sensitivity to catecholamines (hormones like adrenaline)
Potential genetic predisposition
Possible association with certain autoimmune conditions or infections (rare).
Medicine Used
Medications used to manage IST symptoms may include:
Beta-blockers: Slow heart rate (e.g., metoprolol, bisoprolol).
Calcium channel blockers: Slow heart rate (e.g., verapamil, diltiazem).
Ivabradine: Selectively slows heart rate by inhibiting the If current in the sinus node.
Anti-anxiety medications: May be prescribed if anxiety is a significant trigger. Note: Medication choices and dosages are highly individualized and must be determined by a physician.
Is Communicable
No, Inappropriate Sinus Tachycardia is not a communicable or infectious disease. It cannot be spread from person to person.
Precautions
While there are no specific precautions to prevent IST since the cause is often unknown, lifestyle modifications that may help manage symptoms include:
Avoiding excessive caffeine and alcohol
Managing stress through relaxation techniques (e.g., yoga, meditation)
Staying hydrated
Regular exercise (as tolerated and with physician guidance)
Avoiding medications or substances that may increase heart rate (e.g., decongestants)
How long does an outbreak last?
IST is not an "outbreak" but a chronic condition. The duration of symptoms can vary greatly from person to person. Some individuals may experience persistent tachycardia, while others may have intermittent episodes. Symptoms can be ongoing unless managed with medication or other interventions.
How is it diagnosed?
Diagnosis typically involves:
Electrocardiogram (ECG or EKG): To record the heart's electrical activity and identify rapid heart rate.
Holter monitor: A portable ECG that records heart activity over 24-48 hours to capture intermittent episodes.
Event monitor: Similar to a Holter monitor, but worn for longer periods (weeks to months) and activated by the patient when symptoms occur.
Exercise stress test: To evaluate heart rate response to physical exertion.
Blood tests: To rule out other conditions that can cause tachycardia, such as hyperthyroidism or anemia.
Tilt table test: To assess for orthostatic hypotension or other autonomic nervous system dysfunction.
Ruling out other causes of tachycardia A formal diagnosis is made by a cardiologist after a thorough evaluation.
Timeline of Symptoms
The onset of symptoms can be gradual or sudden. Some individuals may notice palpitations or rapid heart rate developing over time, while others may experience abrupt episodes. The duration of symptoms can range from minutes to hours or even days. Without treatment, symptoms may persist indefinitely, varying in intensity.
Important Considerations
IST can significantly impact quality of life due to debilitating symptoms like fatigue and dizziness.
A thorough evaluation by a cardiologist is crucial to rule out other causes of tachycardia.
Treatment is aimed at managing symptoms and improving quality of life.
Lifestyle modifications can play a supportive role in symptom management.
Catheter ablation, a procedure to destroy the part of the sinus node causing the rapid heart rate, can be considered in some cases where medications are ineffective or not tolerated.
Long-term follow-up with a cardiologist is essential to monitor the condition and adjust treatment as needed.