What is Supraventricular Tachycardia (SVT)?
Supraventricular Tachycardia (SVT) refers to a group of arrhythmias (abnormal heart rhythms) that originate above the ventricles in the heart. SVT results in a rapid heart rate, typically ranging from 150 to 250 beats per minute, causing palpitations and discomfort.
SVT can occur in people with otherwise healthy hearts, but it can also be linked to structural heart problems, stress, or certain lifestyle factors. While SVT itself is not usually life-threatening, it can be uncomfortable and may require treatment if episodes are frequent or prolonged.
Causes and Risk Factors
SVT can result from an electrical malfunction in the heart, where the electrical signals that regulate the heart's rhythm become abnormal. Common causes and risk factors for SVT include:
- Heart Disease: Structural issues, such as heart valve problems or congenital heart defects, can lead to SVT.
- Previous Heart Surgery: A history of heart surgery, especially involving the heart's electrical pathways, increases the risk of SVT.
- Stress and Anxiety: Emotional stress or anxiety can sometimes trigger SVT episodes.
- Caffeine or Alcohol Consumption: Excessive intake of caffeine or alcohol may trigger SVT in some individuals.
- Electrolyte Imbalances: Low levels of potassium or magnesium in the blood can affect the heart’s electrical activity.
- Thyroid Disorders: Both hyperthyroidism and hypothyroidism can affect heart rhythm and increase the risk of SVT.
- Stimulant Medications: Certain medications, such as decongestants or stimulants, can increase heart rate and trigger SVT.
- Genetic Factors: A family history of arrhythmias may increase the likelihood of developing SVT.
Symptoms of Supraventricular Tachycardia (SVT)
The symptoms of SVT can vary in intensity, with some people experiencing no symptoms at all. Common symptoms include:
- Palpitations: A feeling of rapid, pounding, or irregular heartbeats.
- Chest Discomfort: Some individuals experience mild to moderate chest pain or tightness during episodes.
- Dizziness or Lightheadedness: Reduced blood flow can lead to dizziness or feeling faint.
- Shortness of Breath: Difficulty breathing, especially during physical exertion.
- Fatigue: The heart’s inability to pump blood efficiently during episodes can lead to fatigue and weakness.
- Anxiety or Panic: Rapid heartbeats may cause feelings of anxiety or panic, especially in severe episodes.
If symptoms become severe or if a person experiences fainting, severe chest pain, or extreme dizziness, emergency medical attention is needed.
Diagnosis of Supraventricular Tachycardia (SVT)
Doctors use several diagnostic methods to determine if SVT is the cause of symptoms. These methods include:
- Electrocardiogram (ECG): The most common and effective method for diagnosing SVT, an ECG records the heart’s electrical activity and can identify irregular heart rhythms.
- Holter Monitor: A portable ECG device worn for 24-48 hours that continuously records heart rhythm to detect intermittent episodes of SVT.
- Echocardiogram: An ultrasound of the heart to assess heart structure and identify any underlying heart disease.
- Electrophysiology Study: A test where doctors use catheters to map the heart’s electrical activity, locate abnormal pathways, and determine the cause of the arrhythmia.
Treatment and Management
SVT treatment focuses on stopping the rapid heart rate during an episode and preventing future episodes. Treatment options include:
- Vagal Maneuvers: Simple techniques, such as coughing, holding your breath, or placing a cold towel on the face, may help slow the heart rate during an episode.
- Medications:
- Beta-Blockers: Medications that reduce the heart rate and help control episodes of SVT.
- Calcium Channel Blockers: These help relax the heart and slow the heart rate.
- Antiarrhythmic Drugs: Medications used to restore and maintain normal heart rhythm.
- Cardioversion: In cases where medications or vagal maneuvers do not work, doctors may use electrical cardioversion to reset the heart’s rhythm.
- Catheter Ablation: A procedure in which a catheter is used to destroy the abnormal electrical pathways in the heart that cause SVT.
- Pacemaker: In rare cases, a pacemaker may be needed to regulate the heart rate, especially if episodes are frequent or prolonged.
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