SVT

SVT
Name	SVT
Field	Cardiology
Symptoms	Palpitations, dizziness, syncope, chest pain
Complications	Thromboembolism, heart failure, cardiogenic shock
Onset	Any age
Causes	Re-entrant circuits, accessory pathways, ectopic foci
Diagnosis	ECG, Holter monitor, electrophysiology study
Treatment	Vagal maneuvers, adenosine, beta blockers, catheter ablation

SVT is a group of arrhythmias characterized by rapid heart rhythm originating above the ventricular conduction system. It commonly produces episodic palpitations and can range from benign paroxysms to hemodynamically significant tachycardia requiring urgent intervention. Management spans acute vagal maneuvers and pharmacotherapy to definitive catheter ablation by electrophysiologists.

Definition and Classification

Supraventricular tachycardias encompass arrhythmias arising from atrial tissue, atrioventricular nodal tissue, or accessory pathways, and are classified by mechanism and rate. Classic categories include atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia mediated by accessory pathways such as Kent bundles, focal atrial tachycardia, and atrial flutter with variable conduction. Subclassification often references electrophysiological properties used in studies from centers like Mayo Clinic, Cleveland Clinic, and research institutions such as Johns Hopkins Hospital and Massachusetts General Hospital.

Epidemiology and Risk Factors

Paroxysmal forms of supraventricular tachycardia have variable incidence across populations studied in cohorts from Framingham Heart Study and registries at tertiary centers including Mount Sinai Health System and UCSF Medical Center. Risk is higher in patients with structural heart lesions treated at Great Ormond Street Hospital or post-operative cohorts from Mayo Clinic pediatric studies. Contributory clinical associations have been reported in patients with thyroid disease treated at Royal College of Physicians–linked clinics, users of stimulants in epidemiologic work from National Institutes of Health, and cohorts with inherited channelopathies evaluated at Karolinska University Hospital and Cleveland Clinic.

Pathophysiology and Mechanisms

Mechanisms include re-entry, triggered activity, and enhanced automaticity documented in electrophysiology studies pioneered at Stanford University School of Medicine and UCLA Health. Re-entrant circuits often involve the atrioventricular node or concealed accessory pathways described in case series from Guy's and St Thomas' NHS Foundation Trust and experimental work at Imperial College London. Molecular mechanisms implicating sodium and potassium channel mutations have been characterized by laboratories at Broad Institute and University of Oxford, influencing risk stratification in inherited arrhythmia clinics at St Bartholomew's Hospital.

Clinical Presentation and Diagnosis

Patients present with rapid regular palpitations, presyncope, syncope, or chest discomfort; evaluation pathways mirror protocols from American Heart Association and European Society of Cardiology guidelines. Initial diagnosis relies on electrocardiography with narrow QRS tachycardia patterns recorded in emergency departments at Beth Israel Deaconess Medical Center and ambulatory telemetry from Toronto General Hospital. Extended monitoring with Holter or event recorders developed by teams at Johns Hopkins Hospital and implantable loop recorders used in studies from Cleveland Clinic assist in intermittent presentations. Definitive characterization often requires invasive electrophysiology study performed in catheterization labs at Mayo Clinic and Mount Sinai Health System.

Management and Treatment

Acute management emphasizes vagal maneuvers taught in protocols from American Red Cross training and intravenous adenosine per emergency regimens endorsed by European Resuscitation Council and American Heart Association. Rate control and prevention use beta blockers, nondihydropyridine calcium channel blockers, and antiarrhythmic agents with prescribing patterns reviewed in pharmacoepidemiology reports from Food and Drug Administration databases and trials conducted at National Heart, Lung, and Blood Institute. Catheter ablation using radiofrequency or cryoablation techniques, with outcomes reported by centers such as Cleveland Clinic and Mayo Clinic, offers curative potential and is guided by mapping systems developed by companies collaborating with Massachusetts General Hospital and Stanford University School of Medicine investigators. Anticoagulation decisions in atrial arrhythmias follow stroke risk schemas promoted by European Society of Cardiology and studies from Queen Mary University of London.

Prognosis and Complications

Long-term outlook varies by subtype and comorbidity, with procedural success and recurrence rates published in multicenter series from Cleveland Clinic, Mayo Clinic, and Johns Hopkins Hospital. Potential complications include tachycardia-induced cardiomyopathy observed in cohort studies at University College London Hospitals and thromboembolic events documented in analysis from Framingham Heart Study collaborators. Mortality is low in isolated cases treated at specialized centers such as UCSF Medical Center but increases with concomitant structural heart disease managed in referrals to Mount Sinai Health System and tertiary care networks.

Category:Cardiac arrhythmias