What is the management of paroxysmal supraventricular tachycardia (PSVT)?

Management of Paroxysmal Supraventricular Tachycardia (PSVT)

For acute PSVT management, begin with vagal maneuvers in stable patients, followed immediately by adenosine if unsuccessful, while unstable patients require immediate synchronized cardioversion. 1

Acute Management Algorithm

Hemodynamically Unstable Patients

• Perform immediate synchronized cardioversion starting at 50-100 J (biphasic), increasing energy stepwise if the initial shock fails 1, 2
• Do not delay cardioversion for vagal maneuvers or pharmacologic therapy when the patient shows signs of hemodynamic instability (hypotension, altered mental status, acute heart failure, or ongoing chest pain) 1

Hemodynamically Stable Patients

First-Line: Vagal Maneuvers

• Initiate vagal maneuvers immediately as they terminate up to 25-27.7% of PSVT episodes 1, 2
• Modified Valsalva maneuver (43% effective): Patient bears down against a closed glottis for 10-30 seconds while supine, generating at least 30-40 mm Hg intrathoracic pressure 1, 3
• Carotid sinus massage: Apply steady pressure over the carotid sinus for 5-10 seconds after confirming absence of bruit by auscultation; perform on right or left side separately, never simultaneously 1
• Diving reflex: Apply ice-cold wet towel to the face or facial immersion in 10°C water 1
• Switching between vagal maneuver techniques increases overall success rates 1

Second-Line: Adenosine

• Adenosine is the preferred pharmacologic agent with 91-95% effectiveness in terminating AVNRT 1, 2, 3
• Dosing: 6 mg IV rapid push through a large vein, followed immediately by 20 mL saline flush; if unsuccessful after 1-2 minutes, give 12 mg IV rapid push 1, 2
• Adenosine serves dual diagnostic and therapeutic roles by unmasking atrial activity in atrial flutter or atrial tachycardia if PSVT does not terminate 1
• Contraindications: Severe bronchial asthma (absolute), second- or third-degree AV block without pacemaker 1
• Drug interactions: Theophylline reduces effectiveness (may require higher doses), dipyridamole potentiates effects, carbamazepine increases risk of heart block 1
• Adverse effects: May trigger transient atrial fibrillation in 1-15% of patients, particularly problematic in patients with ventricular pre-excitation 1

Third-Line: Calcium Channel Blockers or Beta Blockers

• Intravenous diltiazem or verapamil are particularly effective with 80-98% success rates for converting AVNRT to sinus rhythm 1, 2
• These agents are more effective than beta blockers for acute termination 1
• Intravenous beta blockers (such as metoprolol) are reasonable alternatives but less effective than calcium channel blockers 1, 2
• Critical warning: Use extreme caution with concomitant IV calcium channel blockers and beta blockers due to potentiation of hypotensive and bradycardic effects 1
• Contraindication: Never use in patients with Wolff-Parkinson-White syndrome with pre-excitation or pre-excited atrial fibrillation, as these agents may accelerate ventricular response and precipitate ventricular fibrillation 2

Fourth-Line: Synchronized Cardioversion

• If pharmacologic therapy fails or is contraindicated in stable patients, proceed to synchronized cardioversion 1

Long-Term Management

First-Line: Catheter Ablation

• Catheter ablation is the first-line therapy for recurrent symptomatic PSVT with single-procedure success rates of 94.3-98.5% and low complication rates 2, 3, 4
• Electrophysiological study with ablation provides both definitive diagnosis and treatment 2
• Ablation is particularly recommended for patients with frequent episodes, those requiring chronic medication, or those preferring definitive cure 4

Pharmacologic Suppression (When Ablation Declined or Not Feasible)

First-Line Medications

• Oral beta blockers, diltiazem, or verapamil are first-line pharmacological options for symptomatic patients without ventricular pre-excitation 2
• These agents prevent recurrence but do not cure the underlying substrate 4

Second-Line Medications

• Flecainide or propafenone are second-line options reserved for patients without structural heart disease or ischemic heart disease 2
• Flecainide is FDA-approved for prevention of PSVT in patients without structural heart disease 5
• Propafenone reduced PSVT recurrence with 47% of patients remaining attack-free versus 16% on placebo, with median time to first recurrence >98 days versus 12 days 6
• Critical contraindication: These agents should not be used in patients with structural heart disease, coronary artery disease, or recent myocardial infarction due to proarrhythmic risk 6, 5

Special Considerations for Wolff-Parkinson-White Syndrome

• Patients with WPW and pre-excited atrial fibrillation require different management 2
• For hemodynamically unstable patients: Immediate synchronized cardioversion 2
• For hemodynamically stable patients: Ibutilide or intravenous procainamide 2, 7
• Absolutely avoid AV nodal blocking agents (adenosine, beta blockers, calcium channel blockers, digoxin) in patients with WPW and pre-excitation, as these may accelerate ventricular response and cause ventricular fibrillation 2

Patient Education and Self-Management

• Teach patients proper technique for performing vagal maneuvers for self-termination of episodes at home 2
• Patients should be instructed to seek emergency care if episodes do not terminate with vagal maneuvers, last longer than usual, or are associated with severe symptoms 3

Diagnostic Pearls During Acute Management

• Obtain 12-lead ECG during tachycardia whenever possible before termination, but do not delay treatment in unstable patients 1
• Record ECG during adenosine administration or vagal maneuvers, as the response aids diagnosis even if arrhythmia does not terminate 1
• Termination with a P wave after the last QRS favors AVRT or AVNRT; termination with a QRS favors atrial tachycardia 1
• Continuation of tachycardia with AV block is diagnostic of atrial tachycardia or atrial flutter and excludes AVRT 1