Paroxysmal Supraventricular Tachycardia (PSVT)

Overview

Paroxysmal Supraventricular Tachycardia is a heart rhythm disorder characterized by episodes of rapid heart rate that begin and end abruptly. The term "paroxysmal" refers to the sudden onset and offset, "supraventricular" indicates the abnormal rhythm originates above the heart's ventricles (in the atria or AV node), and "tachycardia" means rapid heart rate. PSVT is one of the most common arrhythmias encountered in clinical practice, affecting people of all ages, though it often first appears in young adulthood.

During a PSVT episode, an abnormal electrical circuit in the heart causes it to beat much faster than normal. This rapid rhythm typically involves a reentry circuit, where electrical impulses travel in a circular pattern through the heart tissue. The most common types of PSVT include atrioventricular nodal reentrant tachycardia (AVNRT), accounting for about 60% of cases, atrioventricular reentrant tachycardia (AVRT), which involves an accessory pathway, and atrial tachycardia.

While PSVT episodes can be alarming and uncomfortable, they are rarely dangerous in people with otherwise healthy hearts. However, frequent or prolonged episodes can lead to complications, particularly in those with underlying heart disease. The condition can significantly affect daily activities, exercise tolerance, and overall quality of life. Fortunately, various effective treatments are available, ranging from simple vagal maneuvers to medications and catheter ablation procedures that can potentially cure the condition.

Symptoms

PSVT symptoms typically begin and end suddenly, lasting from a few seconds to several hours. The severity and frequency of symptoms vary greatly among individuals, with some experiencing mild discomfort while others have debilitating episodes.

Primary Cardiac Symptoms

• Palpitations - Sensation of rapid, fluttering, or pounding heartbeat
• Increased heart rate - Typically 150-250 beats per minute during episodes
• Irregular heartbeat - Though the rhythm is usually regular during PSVT
• Sharp chest pain - May occur due to rapid heart rate
• Chest tightness - Pressure or discomfort in the chest

Associated Symptoms

• Shortness of breath - Difficulty breathing during episodes
• Dizziness - Lightheadedness or feeling faint
• Weakness - General fatigue or loss of strength
• Anxiety or panic sensations
• Sweating or clamminess
• Nausea
• Neck pulsations or throat fluttering

Less Common Symptoms

• Involuntary urination - May occur at the end of prolonged episodes
• Syncope (fainting) - Rare but may occur with very rapid rates
• Confusion or altered mental state during severe episodes
• Fatigue following episodes

Symptom Patterns

PSVT episodes exhibit characteristic patterns:

• Sudden onset: Symptoms start abruptly, often described as a "switch" being flipped
• Consistent rate: Heart rate remains steady during the episode
• Abrupt termination: Episodes stop as suddenly as they start
• Variable duration: May last seconds to hours, rarely days
• Post-episode effects: Fatigue, frequent urination, or weakness may follow

Causes

PSVT results from abnormal electrical pathways or circuits in the heart that allow rapid firing of electrical impulses. Understanding these mechanisms helps in selecting appropriate treatment strategies.

Types and Mechanisms

Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

• Most common type (60% of PSVT cases)
• Involves two pathways within or near the AV node
• Electrical impulse travels in a circuit between fast and slow pathways
• More common in women and typically begins in young adulthood

Atrioventricular Reentrant Tachycardia (AVRT)

• Second most common type (30% of cases)
• Involves an accessory pathway (bypass tract) between atria and ventricles
• Wolff-Parkinson-White syndrome is a subtype when pathway is visible on ECG
• Often diagnosed in childhood or adolescence

Atrial Tachycardia

• Abnormal focus in the atria fires rapidly
• May be focal (single site) or multifocal
• Can be related to structural heart disease
• Sometimes triggered by stimulants or medications

Triggers

Common factors that can precipitate PSVT episodes include:

• Physical triggers:
  • Sudden movements or position changes
  • Bending over
  • Exercise or physical exertion
  • Straining during bowel movements
• Substances:
  • Caffeine consumption
  • Alcohol intake
  • Nicotine/smoking
  • Recreational drugs (cocaine, amphetamines)
  • Certain medications (decongestants, asthma inhalers)
• Physiological factors:
  • Emotional stress or anxiety
  • Lack of sleep or fatigue
  • Dehydration
  • Hormonal changes (pregnancy, menstruation)
  • Fever or illness

Risk Factors

While PSVT can affect anyone, certain factors increase the likelihood of developing this condition:

Demographic Factors

• Age: Can occur at any age but often begins in teens or early adulthood
• Gender: AVNRT is more common in women; AVRT affects both sexes equally
• Family history: Some forms have genetic components

Medical Conditions

• Congenital heart conditions: Including accessory pathways
• Heart disease: Coronary artery disease, heart failure, or valve problems
• Thyroid disorders: Particularly hyperthyroidism
• Lung disease: COPD or pulmonary hypertension
• Previous heart surgery: May create substrate for arrhythmias

Lifestyle Factors

• Stimulant use: Excessive caffeine, energy drinks
• Alcohol consumption: Particularly binge drinking
• Drug use: Cocaine, methamphetamines, marijuana
• Chronic stress: Work-related or personal stress
• Sleep deprivation: Irregular sleep patterns
• Dehydration: Inadequate fluid intake

Medications

• Decongestants containing pseudoephedrine
• Asthma medications (bronchodilators)
• Some antidepressants
• Digitalis (in toxic doses)
• Some herbal supplements

Diagnosis

Diagnosing PSVT requires capturing the abnormal rhythm, which can be challenging due to the episodic nature of the condition. A systematic approach helps ensure accurate diagnosis and appropriate treatment planning.

Clinical History

Detailed history-taking focuses on:

• Description of palpitation episodes (onset, duration, termination)
• Associated symptoms during episodes
• Frequency and pattern of occurrences
• Identified triggers or precipitating factors
• Response to any attempted interventions
• Impact on daily activities and quality of life
• Family history of arrhythmias or sudden death

Diagnostic Tests

Electrocardiogram (ECG)

• 12-lead ECG during episodes is diagnostic
• Shows narrow QRS complex tachycardia (usually)
• May reveal pre-excitation (delta waves) in WPW syndrome
• Between episodes, ECG is often normal

Ambulatory Monitoring

• Holter monitor: 24-48 hour continuous recording
• Event recorder: Patient-activated during symptoms
• Loop recorder: Extended monitoring for weeks
• Implantable loop recorder: For very infrequent episodes
• Smartphone ECG devices: Increasingly used for documentation

Additional Testing

• Echocardiogram: Evaluates heart structure and function
• Exercise stress test: May provoke episodes
• Blood tests: Thyroid function, electrolytes, cardiac biomarkers
• Electrophysiology study: Definitive diagnosis and treatment planning

Differential Diagnosis

Conditions that may mimic PSVT include:

• Atrial fibrillation or flutter
• Sinus tachycardia
• Ventricular tachycardia
• Panic attacks or anxiety disorders
• Hyperthyroidism

Treatment Options

PSVT treatment aims to terminate acute episodes, prevent recurrences, and improve quality of life. Treatment selection depends on episode frequency, severity, and patient preference.

Acute Episode Management

Vagal Maneuvers

First-line treatment for stable patients:

• Valsalva maneuver: Bear down as if having a bowel movement
• Carotid sinus massage: Performed by healthcare provider
• Cold water facial immersion: Diving reflex
• Modified Valsalva: Lie flat with legs elevated after standard Valsalva
• Success rate: 20-40% for standard maneuvers, up to 54% for modified Valsalva

Medications for Acute Treatment

• Adenosine:
  • First-line medication if vagal maneuvers fail
  • Rapid IV push: 6mg, then 12mg if needed
  • Very brief half-life, transient side effects
  • Success rate >90%
• Calcium channel blockers: Verapamil or diltiazem IV
• Beta blockers: Esmolol or metoprolol IV
• Electrical cardioversion: For hemodynamically unstable patients

Long-term Management

Medications for Prevention

• Beta blockers:
  • Metoprolol, atenolol, or propranolol
  • First-line for most patients
  • Reduce episode frequency and severity
• Calcium channel blockers:
  • Diltiazem or verapamil
  • Alternative to beta blockers
  • Avoid in WPW syndrome
• Antiarrhythmic drugs:
  • Flecainide or propafenone
  • For refractory cases
  • Require close monitoring

Catheter Ablation

• Curative treatment for most PSVT types
• Success rates: 95% for AVNRT, 93% for AVRT
• Low complication rate (<1%)
• Procedure involves:
  • Electrophysiology study to locate abnormal pathway
  • Radiofrequency or cryoablation to eliminate pathway
  • Usually performed as outpatient procedure
• Indications:
  • Frequent or severe symptoms
  • Medication failure or intolerance
  • Patient preference to avoid long-term medication
  • High-risk occupations (pilots, drivers)

Self-Management Strategies

• Learn and practice vagal maneuvers
• Keep symptom diary to identify triggers
• Carry medical information card
• Consider wearable ECG device for documentation
• Join support groups for arrhythmia patients

Prevention

While not all PSVT episodes can be prevented, identifying and avoiding triggers can significantly reduce their frequency and severity.

Lifestyle Modifications

• Dietary changes:
  • Limit or avoid caffeine (coffee, tea, energy drinks)
  • Moderate alcohol consumption
  • Stay well-hydrated
  • Avoid large meals that can trigger vagal responses
  • Maintain regular meal times
• Stress management:
  • Practice relaxation techniques (meditation, yoga)
  • Regular exercise (with physician approval)
  • Adequate sleep (7-9 hours nightly)
  • Counseling for anxiety or stress
• Activity modifications:
  • Avoid sudden position changes
  • Rise slowly from lying or sitting
  • Be cautious with activities that involve straining

Medical Management

• Take preventive medications as prescribed
• Regular follow-up with cardiologist
• Monitor and manage other cardiac risk factors
• Treat underlying conditions (thyroid disease, sleep apnea)
• Review all medications with healthcare provider

Trigger Avoidance

• Keep detailed diary of episodes and preceding activities
• Identify personal triggers through pattern recognition
• Avoid known precipitants when possible
• Plan activities to minimize trigger exposure
• Educate family members about condition and triggers

When to See a Doctor

Knowing when to seek medical attention for PSVT is crucial for proper management and preventing complications.

Seek Emergency Care If:

• First episode of rapid heartbeat lasting more than 20 minutes
• Severe sharp chest pain or pressure
• Significant shortness of breath or difficulty breathing
• Loss of consciousness or near-fainting
• Heart rate exceeding 250 beats per minute
• Symptoms don't respond to usual interventions
• Associated with severe dizziness or confusion
• New or worsening symptoms compared to previous episodes

Schedule an Appointment For:

• New onset of palpitations or racing heart
• Increasing frequency or duration of episodes
• Episodes interfering with daily activities
• Side effects from current medications
• Interest in curative treatment options
• Need for work or activity restrictions evaluation
• Pregnancy planning with known PSVT
• Persistent weakness or fatigue between episodes

Regular Monitoring Needed If:

• Taking antiarrhythmic medications
• Have underlying heart disease
• Experiencing medication side effects
• Episodes becoming more frequent
• Developing new cardiac symptoms

Related Conditions

Several conditions may be associated with or mistaken for PSVT:

• Atrial Fibrillation - Another common supraventricular arrhythmia
• Wolff-Parkinson-White Syndrome - Type of PSVT with accessory pathway
• Atrial Flutter - Related rhythm disorder
• Ventricular Tachycardia - More serious rapid rhythm
• Panic Disorder - Can mimic PSVT symptoms
• Hyperthyroidism - Can trigger or worsen PSVT
• Sick Sinus Syndrome - May alternate with tachycardia
• Inappropriate Sinus Tachycardia - Different mechanism