Paroxysmal Supraventricular Tachycardia

PSVT is primarily caused by electrical malfunctions in the heart's conduction system. Research published in Circulation (2023) suggests that most cases result from "reentry," where an electrical impulse gets caught in a loop. This is often due to the presence of two pathways in the AV node with different conduction speeds and recovery times. When a premature beat occurs at the right moment, it can trigger the rapid looping rhythm.

Non-Modifiable Risk Factors

• Genetics: A family history of arrhythmias can increase risk, particularly in cases of WPW syndrome.
• Age: While it can affect any age, AVNRT is most frequently diagnosed in adults in their 30s and 40s.
• Sex: Women are statistically more prone to developing AVNRT than men.
• Congenital Heart Defects: Structural issues present from birth can include accessory electrical pathways.

Modifiable Risk Factors

• Stimulants: Excessive consumption of caffeine, nicotine, or certain herbal supplements (like ephedra) can trigger episodes.
• Stress and Anxiety: High levels of emotional stress can increase adrenaline, which may trigger the heart's electrical system to misfire.
• Alcohol Consumption: Even moderate alcohol use can be a trigger for some individuals, a phenomenon sometimes called "holiday heart."
• Sleep Deprivation: Lack of rest can sensitize the heart to arrhythmias.

According to the National Institutes of Health (NIH, 2024), individuals with hyperthyroidism (overactive thyroid) or those with chronic lung disease are at a higher risk for atrial-based tachycardias. Additionally, patients who have undergone previous heart surgeries may develop "scar-related" reentry circuits.

While the underlying electrical pathways are often innate, the frequency of episodes can be reduced through trigger avoidance. Evidence-based strategies include maintaining a consistent sleep schedule, limiting stimulant intake, and practicing stress-reduction techniques. For those with frequent episodes, clinical interventions like catheter ablation offer a high success rate (over 90%) for permanent prevention.

The diagnostic journey typically begins when a patient reports palpitations to a primary care provider. Because PSVT is episodic, the heart rhythm may be perfectly normal during a physical examination, making the diagnosis challenging.

During an active episode, a doctor will note a very rapid, regular pulse. Between episodes, the physical exam is often unremarkable, though the physician will check for signs of thyroid issues or heart valve problems.

• Electrocardiogram (ECG/EKG): The gold standard for diagnosis. It records the heart's electrical activity. If captured during an episode, it shows a characteristic rapid, narrow-complex rhythm.
• Holter Monitor: A portable ECG worn for 24-48 hours to catch episodes that occur daily.
• Event Monitor: A device worn for up to 30 days that the patient activates only when they feel symptoms.
• Echocardiogram: An ultrasound of the heart to rule out structural heart disease or valve issues.
• Electrophysiology (EP) Study: An invasive procedure where catheters are threaded into the heart to map the electrical system and intentionally trigger the arrhythmia to identify its exact source.

Clinical diagnosis is confirmed when an ECG shows a regular tachycardia (usually 150–250 bpm) with narrow QRS complexes (less than 120ms), and often, "p-waves" that are hidden or appear just after the QRS complex.

Doctors must distinguish PSVT from other conditions, including:

• Sinus Tachycardia: A normal fast heart rate due to exercise or fever.
• Atrial Fibrillation: An irregular, chaotic rhythm.
• Panic Attacks: Which can cause rapid heart rate but usually involve a gradual onset.
• Hyperthyroidism: Which causes a persistently elevated heart rate.

The primary goals of treating PSVT are to terminate acute episodes, prevent future recurrences, and improve the patient's quality of life. Success is measured by the reduction in episode frequency and the elimination of symptoms like syncope or chest pain.

For acute episodes, the first-line approach per the American College of Cardiology (ACC) guidelines involves Vagal Maneuvers. These are physical actions that stimulate the vagus nerve to slow the heart rate. Examples include the Valsalva maneuver (bearing down as if having a bowel movement) or coughing. If these fail, medical intervention in an emergency setting is required.

Healthcare providers typically consider several classes of medications for both acute termination and long-term management:

• Antiarrhythmics: These work by affecting the sodium or potassium channels in the heart cells to reset the rhythm. They are often used when other treatments are not tolerated.
• Calcium Channel Blockers (Non-Dihydropyridine): These slow the conduction of electrical impulses through the AV node. Common side effects include constipation and low blood pressure.
• Beta-Blockers: These block the effects of adrenaline on the heart, slowing the heart rate and reducing the force of contraction. They are often preferred for long-term prevention.
• Adenosine: Used exclusively in a hospital setting via IV, this medication momentarily "stops" the heart's electrical activity to break the reentry circuit.

If single-agent therapy is ineffective, doctors may combine a beta-blocker with an antiarrhythmic. However, this requires close monitoring due to the risk of bradycardia (excessively slow heart rate).

• Catheter Ablation: This is often considered the definitive treatment. A specialist (electrophysiologist) uses radiofrequency energy or cold (cryoablation) to destroy the tiny area of heart tissue causing the short circuit.
• Synchronized Cardioversion: In emergency cases where a patient is unstable, a controlled electrical shock is delivered to the heart to reset the rhythm.

Medication may be required indefinitely unless the patient undergoes a successful ablation. Monitoring typically involves periodic ECGs and checking for medication side effects.

In pregnancy, many antiarrhythmic drugs are avoided due to potential risks to the fetus; vagal maneuvers and certain beta-blockers are generally preferred. In the elderly, lower doses are often used to avoid excessive slowing of the heart.

> Important: Talk to your healthcare provider about which approach is right for you.

While diet does not cause PSVT, certain substances can trigger episodes. A study in the American Journal of Clinical Nutrition suggests that while moderate caffeine is safe for most, individuals with PSVT should monitor their sensitivity. Avoiding excessive alcohol and staying hydrated is crucial, as electrolyte imbalances (low magnesium or potassium) can make the heart more prone to arrhythmias.

Most patients with PSVT can and should exercise. However, high-intensity "burst" exercises may trigger episodes in some. It is recommended to perform a gradual warm-up and cool-down. If an episode occurs during exercise, stop immediately and perform vagal maneuvers as instructed by your doctor.

Sleep apnea has been linked to increased cardiac arrhythmias. Ensuring 7-9 hours of quality sleep can reduce the sympathetic nervous system's "fight or flight" activity, potentially lowering the frequency of PSVT episodes.

Evidence-based techniques such as Mindfulness-Based Stress Reduction (MBSR) and diaphragmatic breathing can help stabilize the autonomic nervous system. Lowering chronic stress levels reduces the baseline heart rate and may prevent the "premature beats" that trigger PSVT.

Some patients find relief through acupuncture or yoga, though clinical evidence for these as primary treatments is limited. Magnesium supplementation may be discussed with a doctor if a deficiency is present, but it should never replace prescribed medical therapy.

Caregivers should learn how to help the patient perform a Valsalva maneuver correctly. It is also helpful to keep a log of the patient's episodes, noting the duration, triggers, and symptoms to provide accurate data for the electrophysiologist.

The prognosis for PSVT is generally excellent. For the vast majority of patients, the condition is not life-threatening and does not increase the risk of a heart attack or stroke in the absence of other heart conditions. According to the Cleveland Clinic (2024), catheter ablation has a success rate exceeding 95% for most types of PSVT, effectively curing the condition.

If left untreated and if episodes are very frequent or prolonged, complications can include:

• Tachycardia-induced Cardiomyopathy: A weakening of the heart muscle due to prolonged rapid heart rates.
• Heart Failure: Occurs if the heart cannot meet the body's demands over time.
• Syncope-related Injuries: Falls or accidents resulting from fainting.

Long-term management focuses on monitoring for recurrence. Patients who have had an ablation usually require a follow-up visit at 3 and 12 months. Those on medication may need annual check-ups to monitor kidney and liver function, depending on the drug class.

Most people live full, active lives. Understanding your triggers and knowing how to stop an episode using vagal maneuvers can provide a sense of control and reduce the anxiety associated with the condition.

Contact your healthcare provider if your episodes become more frequent, last longer, or if you begin to experience new symptoms like chest pain or near-fainting. These may indicate that your current treatment plan needs adjustment.