Paroxysmal Supraventricular tachycardia (PSVT)

Refers to paroxysmal tachyarrhythmia (PSVT) which requires atrial and/or atrioventricular nodal tissue for initiation and maintenance.

Requires extra electrical tissue above the Bundle of His to occur.

Occurs at a heart rate is greater than 100/minute, they typically conduct through the his His-Purkinje system, and appear as narrow QRS tachyarrhythmias on ECG.

Paroxysmal SVT (PS T) refers to a group of SVT that begins episodically and terminates abruptly.

The major types of paroxysmal SVT are AV nodal reentrant tachycardia and focal atrial tachycardia.

Atrioventricular nodal reentry tachycardia is the most common type of paroxysmal supraventricular tachycardia and represent approximately 56% of cases referred for ablation.

Atrioventricular reentrant tachycardia is the second most common form of PSVT referred for ablation at 27% of cases, and involves re-entry via an accessory pathway.

Focal atrial tachycardia is the third most common type of PSVT counting for 17% of cases referred for ablation.

Focal atrial tachycardiaIncreases with age and can be enhanced by automaticity, triggered activity, or reentry in diseased atria.

The major comorbidities to paroxysmal SVT include: pulmonary disease, diabetes, heart failure, cerebral vascular disease, and peripheral vascular disease.

Antegrade conduction through the accessory pathway during sinus rhythm, can inscribe a slurred QRS upstroke associated with a short PR interval known as Wolff-Parkinson-White pattern.

Incidence is about 35 cases per 100,000 persons per year.

Prevalence about 2.25 per 1000.

Patients with symptomatic tachycardia require immediate medical attention.

Immediate treatment is tailored to the characteristics of the ventricular response.

Wide complex QRS tachycardias carry a more dangerous differential diagnosis including ventricular tachycardia and torsades de pointes that can degenerate to even more malignant and life-threatening arrhythmias.

Adenosine can worsen wide QRS tachycardias and should not be given.

Adenosine 6 mg intravenously is the usual maneuver for narrow complex tachycardia as it blocks atrioventricular nodal conduction and slows most such tachycardias.

Cardioversion is considered early in wide QRS tachycardia.

By focusing on the ventricular response in supraventricular tachycardia is one can diagnose and divide the patients into seven clinically relevant supraventricular tachycardia.

Sinus tachycardia is the most common supraventricular tachycardia, and it is a non-pathologic arrhythmia, but it is a cardiac response to a physiological event.

Ambulatory monitoring study of 301 men with a mean age of 56 years, and 20% with coronary artery disease, any form of supraventricular tachycardia was found in 56% (Leitch).

In a healthy population of individuals from age 16-65 years a rate of supraventricular tachycardia was noted in 12% (Clarke).

Incidence increases with age and the presence of heart disease.

Occurs in pediatric and adult populations.

Older age associated with increased incidence of PSVT.

Among patients of all ages with PSVT, the majority are female at 67.5%, and 50.3% are age 45 to 64 years.

Patients without cardiovascular disease having lone PSVT accounts for 39% of cases: these patients are on average younger and have faster mean heart rates compared with those with PSVT, and cardiovascular disease.

Frequently recur, occasional is persistent and a frequent cause of medical visits.

Heart rate is at least 100 beats/min, but the ventricular rates can be lower as a result of atrioventricular block.

QRS morphology on electrocardiogram is usually normal or supraventricular, but may be widened or abnormal because of intrinsic conduction disturbance, myocardial disease, or the presence of a bundle branch block.

Atrial fibrillation is the most common pathologic supraventricular tachycardia.

Supraventricular tachycardia in elderly postoperative patients may be a result of electrolyte disturbances, volume overload, myocardial infarction, and atrial fibrillation.

Atrial flutter is the second most common pathologic supraventricular tachycardia and as a result of reentry circuit around the tricuspid valve in the right atrium.

Atypical atrial flutter occurs primarily in persons who have undergone cardiac surgery or cardiac ablation.

When heart rate is 150 beats per minute, flutter waves are likely to ne obscured by T waves, making ECG difficult to distinguish from other supraventicular tachycardias.

Heart rate of 150 beats per minute is suggestive of atrial flutter supraventricular tachyarrhythmia.

The next three most common supraventricular tachycardias are atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, and atrial tachycardia, and they occur in approximately 1 person in 500.

The three above tachycardias are associated with rapid onset of rates 150-250 beats per minute, and regular ventricular response.

Atrioventricular nodal reentrant tachycardia and atrioventricular reciprocating tachycardia are caused by abnormal electrical circuits.

Atrioventricular nodal reentry tachycardia most common among individual 20 years of age or older.

Atrioventricular nodal reentrant tachycardia is the most common sub type of PSVT, accounting, for approximately 56% of cases referred for catheter ablation.

Atrioventricular reentrant tachycardia is the second most common form of PSVT referred for ablation (27% of cases), and involves re-entry via an accessory pathway.

The accessory pathway is an abnormal electrical and anatomical connection between the AV ring between the atria and ventricles.

Accessory pathways occur in one and 1500 individuals at birth.

Atrioventricular reciprocating tachycardia occurs most frequently in the pediatric age group.

Atrial tachycardia can be focal in nature or caused by small abnormal electrical circuits.

Atrial tachycardia is the least common of three above supraventricular tachycardia.

Symptoms include: palpitations, dizziness, anxiety, chest pain, pounding sensation in the neck and chest and dyspnea.

Individuals may experience abrupt onset of symptoms, ranging from palpitations to chest discomfort, shortness of breath, and lightheadedness.

Symptoms are more pronounced that more elevated heart rates and in patience with background coronary artery disease.

Patients with heart failure will experience acute exacerbations and pulmonary edema in association with PSVT.

Syncope is really caused by SVT.

Symptomatic PSVT may terminate spontaneously or persist until intervention.

As a result of release of atrial natriuretic factor polyuria can occur.

May be associated with psychological distress.

Syncope uncommon.


Both the acute and long-term management are important components of PSVT management.

Acute therapy aims to terminate a arrhythmic episode and resolve symptoms.

Increased symptom severity warrants earlier institution of acute therapy.

Long-term therapy prevents recurrence and reduces arrhythmic burden.

Acute vagal maneuvers can stimulate carotid baroreceptors, generate reflex parasympathetic outflow, and slow conduction through the AV node.

Acute vagal maneuvers Serve as first line therapy for patients with hemodynamically stable PSVT.

Vagal maneuvers include the Valsalva maneuver, and carotid, sinus massage.

Adenosine a fast acting adenosine receptors agonist that has a short half-life may be used to treat PSVT.

To terminate paroxysmal, supraventricular tachycardia it is administered as a 6 mg intervenous bolus over one to two seconds.

The success rate of PSVT termination by adenosine is 89.7%.

Non-dihydropyridine calcium channel blockers may be used in acute treatment of PSVT-verapamil, diltiazem.

They have equal efficacy to adenosine in terminating PSVT.

Beta blockers have limited usefulness in terminating PSVT, but can be used as rate control agents.

antiarrhythmic agents may be useful in acute management of PSVT and include propafenone and flecainide.

Emergency synchronized cardioversion is the therapy of choice with patients with PSVT and hemodynamic instability.

Catheter ablation is the first line therapy for symptomatic patients with recurrent PSVT.

Ablation delivers energy that ablates critical sites within re-entrance circuits or at near automatic foci.



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