Paroxysmal Supraventricular Tachycardia (PSVT) is a type of rapid heart rhythm originating above the heart’s ventricles. It is characterized by sudden episodes of fast heartbeats that start and stop abruptly. These episodes often arise from abnormal electrical pathways in the heart, leading to inefficient pumping and symptoms that can range from mild discomfort to severe cardiovascular distress.
Understanding PSVT is important for timely diagnosis and effective treatment. This article provides a detailed overview of the symptoms, causes, and treatment methods for PSVT based on the latest cardiovascular research and clinical guidelines.
What Is Paroxysmal Supraventricular Tachycardia?
Definition and Classification
Paroxysmal Supraventricular Tachycardia is a form of tachyarrhythmia characterized by episodes of rapid heart rate exceeding 100 beats per minute, originating above the ventricles (supraventricular). The term “paroxysmal” refers to its sudden onset and spontaneous termination.
PSVT encompasses several subtypes including atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), and atrial tachycardia. These types differ by their origin and the electrical pathways involved.
Mechanism of PSVT
The normal heartbeat is regulated by an electrical impulse starting at the sinoatrial (SA) node. In PSVT, an abnormal circuit causes rapid electrical signals that override the SA node’s rhythm. This reentrant circuit creates a loop of continuous impulses, resulting in a fast heart rate.
Most commonly, the AV node participates in this circuit, especially in AVNRT. Abnormal accessory pathways, such as in Wolff-Parkinson-White syndrome, cause AVRT. The rapid rate impairs heart filling, reducing cardiac output and triggering symptoms.
Symptoms of Paroxysmal Supraventricular Tachycardia
Common Symptoms
PSVT typically presents with a sudden, rapid heartbeat that may last from seconds to hours. Patients describe palpitations, a sensation of a racing or pounding heart, often exceeding 150 beats per minute. Other frequent symptoms include:
Chest discomfort or tightness: This may mimic angina but usually resolves with termination of the episode.
Shortness of breath: Due to reduced cardiac output and pulmonary congestion.
Dizziness or lightheadedness: Caused by inadequate cerebral perfusion during tachycardia.
Fatigue or weakness: Resulting from prolonged episodes and poor cardiac efficiency.
Anxiety or a feeling of impending doom: Often accompanies palpitations.
Less Common and Severe Symptoms
In some cases, PSVT can cause more serious symptoms, especially in patients with underlying heart disease or prolonged episodes:
Syncope (fainting): Sudden loss of consciousness due to transient cerebral hypoperfusion.
Chest pain resembling a heart attack: Especially in patients with coronary artery disease.
Heart failure symptoms: Such as swelling of the legs and difficulty breathing due to chronic rapid heart rate strain.
When to Seek Medical Attention
Any sudden onset of a rapid heartbeat lasting more than a few minutes should prompt a visit to a healthcare provider. Emergency care is critical if chest pain, syncope, or severe shortness of breath occurs. Early diagnosis can prevent complications.
Causes and Risk Factors of Paroxysmal Supraventricular Tachycardia
Electrical Abnormalities
PSVT arises mainly from abnormalities in the heart’s electrical conduction system. The most common mechanisms include:
Reentry circuits: These cause impulses to loop repeatedly in the atrioventricular node or accessory pathways.
Accessory pathways: Extra electrical connections between atria and ventricles bypass the normal AV node delay, causing early impulses.
Atrial ectopic foci: Abnormal sites in the atria that generate rapid impulses.
Precipitating Factors
Certain factors can trigger PSVT episodes in susceptible individuals, including:
Stress and anxiety: These increase sympathetic nervous system activity, which can provoke arrhythmias.
Caffeine, alcohol, and stimulant use: These substances increase heart rate and may trigger PSVT.
Medications: Some drugs that alter cardiac conduction or electrolyte balance can precipitate episodes.
Underlying heart disease: Conditions like cardiomyopathy, ischemic heart disease, or valve disease increase susceptibility.
Electrolyte imbalances: Low potassium or magnesium can destabilize cardiac electrical activity.
Genetic and Congenital Causes
In some patients, PSVT is linked to inherited abnormalities or congenital conditions such as:
Wolff-Parkinson-White (WPW) Syndrome: A congenital accessory pathway that predisposes to AVRT.
Familial arrhythmia syndromes: Rare genetic mutations affecting ion channels or conduction tissue.
Summary of Risk Factors
To summarize, the major risk factors for PSVT include:
- Presence of accessory electrical pathways.
- Emotional or physical stress.
- Stimulant use (caffeine, nicotine, alcohol).
- Pre-existing heart disease or structural abnormalities.
- Electrolyte disturbances.
- Genetic predisposition or congenital anomalies.
Diagnosis of Paroxysmal Supraventricular Tachycardia
Electrocardiogram (ECG)
The primary diagnostic tool for PSVT is a 12-lead ECG performed during an episode. It reveals a narrow QRS complex tachycardia with a rapid rate, usually between 150-250 beats per minute. The ECG may show absence of P waves or retrograde P waves depending on the type of PSVT.
Holter Monitoring and Event Recorders
Because PSVT episodes are intermittent, a Holter monitor or event recorder may be used to capture arrhythmias during daily activity. These devices record heart rhythms continuously or when triggered by the patient.
Electrophysiological Study (EPS)
In some cases, an invasive EPS is performed. This study maps the heart’s electrical system to precisely locate the abnormal circuit and guide treatment. It is especially useful when planning catheter ablation.
Additional Tests
Other tests may include:
- Blood tests to check electrolytes and thyroid function.
- Echocardiogram to assess cardiac structure and function.
- Exercise stress testing to evaluate inducibility of arrhythmia.
Treatment Options for Paroxysmal Supraventricular Tachycardia
Acute Management of PSVT Episodes
When a patient experiences an acute PSVT episode, the primary goal is to restore normal heart rhythm and relieve symptoms.
Vagal Maneuvers
These are simple physical techniques that stimulate the vagus nerve and slow conduction through the AV node, potentially terminating the arrhythmia. Common maneuvers include:
Valsalva maneuver: Forced exhalation against a closed airway.
Carotid sinus massage: Gentle massage of the carotid artery (performed by medical professionals only).
Coughing or cold water face immersion: Stimulate vagal tone.
Vagal maneuvers can be effective in about 20-30% of cases.
Pharmacologic Therapy
If vagal maneuvers fail, intravenous medications are administered:
Adenosine: The drug of choice, it temporarily blocks AV nodal conduction and often terminates PSVT.
Calcium channel blockers: Such as verapamil or diltiazem, slow AV node conduction.
Beta-blockers: Reduce sympathetic stimulation to the heart.
Electrical Cardioversion
For hemodynamically unstable patients or those with severe symptoms, synchronized electrical cardioversion is performed to reset the heart rhythm safely and quickly.
Long-Term Management and Prevention
Medications
Patients with frequent or symptomatic episodes may require ongoing medications:
- Beta-blockers or calcium channel blockers: Used to reduce episode frequency.
- Antiarrhythmic drugs: Such as flecainide or propafenone, in selected cases.
Catheter Ablation
Catheter ablation is a minimally invasive procedure that destroys the abnormal electrical pathway causing PSVT. It has a high success rate (>90%) and is considered curative for many patients.
This procedure is recommended for patients with recurrent episodes, poor medication tolerance, or high symptom burden.
Lifestyle Modifications
Avoiding triggers such as excessive caffeine, alcohol, and stress can reduce PSVT episodes. Patients are advised to maintain electrolyte balance and seek treatment for underlying heart disease.
Prognosis and Complications of PSVT
PSVT is generally benign but can significantly impact quality of life due to recurrent symptoms. With appropriate treatment, most patients achieve symptom control or cure.
Untreated, frequent or sustained PSVT episodes may lead to complications such as:
Heart failure: Due to persistent rapid heart rates weakening the heart muscle.
Stroke: Rare but possible if atrial fibrillation or thrombus formation occurs.
Psychological distress: Anxiety related to unpredictable episodes.
Conclusion
Paroxysmal Supraventricular Tachycardia is a common arrhythmia with sudden onset and termination. Recognizing symptoms and understanding causes are essential for timely diagnosis. Treatment ranges from vagal maneuvers to catheter ablation, with excellent outcomes. Patients should work closely with their cardiologist to manage and prevent episodes, ensuring optimal heart health and quality of life.
Related topics: