Paroxysmal supraventricular tachycardia
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Noha Elzeiny, M.B.B.Ch, M.Sc.[2]
Synonyms and keywords:PSVT, Narrow QRS complex tachycardia, Atrioventricular nodal reentrant tachycardia, AVNRT, Supraventricular arrhythmia, Supraventricular tachycardia, Tachyarrhythmia, Arrhythmia.
Overview
Paroxysmal Supraventricular tachycardia (PSVT) is a subset of supraventricular tachycardia (SVT), characterized by its episodic nature with sudden onset, sudden offset, regular, rapid rhythm and narrow QRS complex on Electrocardiogram (ECG), usually the patient is normal in between attacks and except for patients with preexisting heart disease, the prognosis is usually good.
Historical Perspective
Catheter-based radiofrequency ablation has improved the treatment of PSVT by precise ablation of the abnormal accessory pathway. First catheter ablations were in the early to mid-1980s, since then it has improved progressively especially in terms of safety and specificity.
Classification
SVTs are classified based on the origin and the regularity of the rhythm:
Atrial in origin:
- Sinus tachycardia
- Inappropriate sinus tachycardia
- Sinoatrial nodal reentrant tachycardia
- Atrial flutter
- Atrial fibrillation
- Multi atrial focal tachycardia
AV nodal in origin:
- Junctional tachycardia
- Atrioventricular nodal reentrant tachycardia
- Atrioventricular reentrant tachycardia
Regular SVT:
- All tachycardia originating from the AV node
- Sinus tachycardia
- Inappropriate sinus tachycardia
- Sinoatrial nodal reentrant tachycardia
- Atrial flutter
Irregular SVT:
- Multifocal atrial tachycardia
- Atrial flutter with variable block
- Atrial fibrillation
Pathophysiology
PSVTs are due to abnormalities in impulse formation and conduction pathways. Often due to different reentry circuits in the heart, less frequent causes include enhanced or abnormal automaticity and triggered activity.
Causes
Reentry circuits are the most common cause
a. About 60% are due to AVNRT either within
- AV node
- Perinodal atrial tissue.
b. 30% are due to Atrioventricular reciprocating tachycardia (AVRT)
- Extranodal accessory pathway connecting the atrium and ventricle, e.g. Wolff-Parkinson-White syndrome (WPW).
c. 10% are due to pathways within or around the sinus node:
- Focal atrial tachycardia
- Intra atrial reentrant tachycardia (IART)
- Sinoatrial nodal reentrant tachycardia (SANRT)
d. Other rare causes (Rare in adults, but can represent a larger portion of PSVTs in children) are due to
- Junctional ectopic tachycardia
- Non-paroxysmal junctional tachycardia
Differentiating Paroxysmal supraventricular tachycardia from other Diseases
Symptoms due to PSVT are often misdiagnosed as psychological disease e.g. panic attacks, stress, anxiety, or depression delaying referral for ablation.
Epidemiology and Demographics
- In the United States, 1.1 to 1.4 million individuals before the age of 65 are affected annually
- Sporadic and unpredictable
- Slightly higher in males than females
- Positively correlated with age
Risk Factors
Any condition or drug that increases automaticity or triggers activity including:
- Abnormal thyroid hormone level
- Caffeine, nicotine, alcohol toxicity and Illicit drugs
- Digoxin and electrolyte abnormalities
- Sympathomimetic drugs
- Stress and anxiety
- Preexisting heart condition, e.g. Congenital heart disease, rheumatic heart disease, cardiomyopathy and previous myocardial infarction
- Lung disease and hypoxia e.g. Chronic lung disease and infection
Screening
Natural History, Complications and Prognosis
- In Absence of underlying heard disease, the PSVT prognosis is favorable.
- Rarely PSVT can cause myocardial infarction, congestive heart failure and even death.
Diagnosis
Diagnostic study of choice | History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | X-Ray Findings | Echocardiography and Ultrasound | CT-Scan Findings | MRI Findings | Other Imaging Findings | Other Diagnostic Studies
The clinical presentation is variable, ranging from asymptomatic to complicated palpitation.
History:
- If present, history of previous self-limiting attacks.
- In some patients there is a past history of preexisting heart disease
Symptoms:
- Asymptomatic
- Some experience episodes palpitations that starts and ends suddenly, may be associated with
- Presyncope, syncope,
- Lightheadedness, dizziness
- Dyspnea, Shortness of breath
- Diaphoresis and/or chest pain.
Physical examination:
- In patients with no underlying disease, the patient is clinically free: If terminated episode of PSVT or in between attacks.
- Tachycardia: Regular, Rapid, abrupt onset, with or without abrupt termination.
- If present Hemodynamic instability and/or lung congestion. Both varies According to the presence of preexisting heart disease
Treatment
Medical Therapy | Interventions | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
PSVTs are managed according to underlying mechanisms and the clinical stability and frequency of episodes.
Hemodynamic unstability or resistance to other treatment modalities: Direct-current cardioversion