Dumirieh
Start free

Rapid Review·Cardiovascular

Select any text to highlight it or add a note.

Arrhythmias: Supraventricular

T1Must know

Wolff-Parkinson-White Syndrome

Focus on

Short PR, delta wave, wide QRS — an accessory pathway (bundle of Kent) bypassing the AV node. Orthodromic AVRT is a narrow regular tachycardia treated like AVNRT; pre-excited AF is an irregular, very fast wide tachycardia where AV-nodal blockers (adenosine, beta blockers, CCBs, digoxin, amiodarone) can precipitate VF — use procainamide, ibutilide or cardioversion. Ablation cures it.

Key takeaways

What it is

Normal conduction versus pre-excitation: in the WPW pattern the accessory pathway lets the impulse reach the ventricle early (a short PR and a delta wave); in WPW syndrome the same pathway forms a re-entrant circuit with the AV node, giving a regular tachycardia.
What this shows
Normal conduction versus pre-excitation: in the WPW pattern the accessory pathway lets the impulse reach the ventricle early (a short PR and a delta wave); in WPW syndrome the same pathway forms a re-entrant circuit with the AV node, giving a regular tachycardia.

An accessory pathway

a congenital accessory pathway (bundle of Kent) connects atrium to ventricle, bypasses the atrioventricular (AV) node, and pre-excites the ventricle.

Pattern vs syndrome

Wolff-Parkinson-White (WPW) pattern is the pre-excitation on the electrocardiogram (ECG) without symptoms; WPW syndrome is the pattern plus tachyarrhythmias.

The arrhythmias

atrioventricular re-entrant tachycardia (AVRT), the most common, and atrial fibrillation or flutter with pre-excitation.

Clinical features

often asymptomatic until an arrhythmia occurs; then palpitations, dizziness, presyncope, chest discomfort, diaphoresis, dyspnea.

Diagnosis

WPW pattern: a short PR interval (double arrow), a slurred upstroke at the start of the QRS (the delta wave, arrow), and a widened QRS.
What this shows
WPW pattern: a short PR interval (double arrow), a slurred upstroke at the start of the QRS (the delta wave, arrow), and a widened QRS.

WPW pattern in sinus rhythm

short PR interval, a delta wave, and a widened QRS.

AVRT

starts abruptly with a regular rhythm at 150 to 250.
Orthodromic versus antidromic AVRT: orthodromic goes down the AV node and back up the accessory pathway (narrow QRS, P wave after the QRS, no delta wave); antidromic goes down the pathway and back up the node (wide QRS; delta and P waves may not be visible).
What this shows
Orthodromic versus antidromic AVRT: orthodromic goes down the AV node and back up the accessory pathway (narrow QRS, P wave after the QRS, no delta wave); antidromic goes down the pathway and back up the node (wide QRS; delta and P waves may not be visible).

Orthodromic AVRT

atrium to AV node to ventricle, back up the pathway.
  • Narrow QRS, the P wave after the QRS, delta waves absent.
  • It can be indistinguishable from AVNRT.

Antidromic AVRT

down the pathway, back up the node.
  • Wide QRS that looks like ventricular tachycardia, with occasional delta waves.

AVRT vs AVNRT

AVRT uses an accessory pathway; AV nodal re-entrant tachycardia (AVNRT) uses two pathways inside the node.
WPW patterns and their acute treatment
PatternQRSDelta waveAV node dependentAcute treatment
WPW in sinus rhythmWideYesYesNone needed
Orthodromic AVRTUsually narrowNoYesVagal maneuvers or adenosine
Antidromic AVRT, or atrial fibrillation (AF) with pre-excitationWideIntermittentNoElectrical cardioversion, or procainamide (first line) or ibutilide

Management

Unstable

synchronized cardioversion.

Stable orthodromic AVRT (narrow)

vagal maneuvers, then adenosine.

Antidromic AVRT or pre-excited atrial fibrillation

electrical cardioversion, or procainamide first line (ibutilide is the alternative).

Asymptomatic low-risk patients

no treatment.

Catheter ablation of the accessory pathway

definitive, and first line for symptomatic or high-risk patients.
  • High risk: syncope, associated atrial fibrillation, flutter or atrial tachycardia, or an aborted sudden death.
A stable 22-year-old with a known delta wave has palpitations; the ECG shows an irregular, wide-complex tachycardia at 240. Which drug is first line, which drugs are dangerous, and what is the long-term fix?

Pre-excited atrial fibrillation in WPW. Give procainamide (or electrical cardioversion). AV nodal blockers (adenosine, beta blockers, calcium-channel blockers, digoxin) push conduction down the pathway and are dangerous. Long term: catheter ablation of the accessory pathway.

How it's tested

A 20-year-old with palpitations; resting ECG shows a PR of 100 ms with a slurred QRS upstroke: WPW pattern — refer for risk stratification and, if symptomatic, ablation.

Same patient in a regular narrow tachycardia at 200, BP normal: orthodromic AVRT — vagal maneuvers, then adenosine.

Same patient in an irregular wide-complex tachycardia at 240 with changing QRS shapes, BP 100/60: pre-excited AF — IV procainamide (or cardioversion); adenosine, diltiazem, metoprolol or digoxin could cause VF.

Same rhythm with BP 70/40: synchronized cardioversion.

What is the definitive therapy after a syncopal episode: catheter ablation of the accessory pathway.

Go deeper

Guidelines: 2015 ACC/AHA/HRS Supraventricular Tachycardia Guideline · 2023 ACC/AHA/ACCP/HRS Atrial Fibrillation Guideline

Related Step 2 pages: AV Nodal Reentrant Tachycardia, Atrial Fibrillation, Approach to Tachyarrhythmias, Ventricular Tachycardia, Ebstein Anomaly, Antiarrhythmic Drugs

High-yield images3
Normal conduction versus pre-excitation: in the WPW pattern the accessory pathway lets the impulse reach the ventricle early (a short PR and a delta wave); in WPW syndrome the same pathway forms a re-entrant circuit with the AV node, giving a regular tachycardia.
WPW pattern: a short PR interval (double arrow), a slurred upstroke at the start of the QRS (the delta wave, arrow), and a widened QRS.
Orthodromic versus antidromic AVRT: orthodromic goes down the AV node and back up the accessory pathway (narrow QRS, P wave after the QRS, no delta wave); antidromic goes down the pathway and back up the node (wide QRS; delta and P waves may not be visible).

Flashcards for this page

Card 1 of 4 · try-out only, nothing is saved

# What is the recommended management for a hemodynamically stable Wolff-Parkinson-White syndrome patient with atrial fibrillation? 

(...)
PreviousAV Nodal Reentrant TachycardiaNextPremature Ventricular Complexes

You just read one page of 236

The rest of Step 2 CK, written exactly like this.

Rapid Review is the reading layer of a full Step 1 platform: a schedule fitted to your exam date, flashcards for every page, and a mentor a message away.

  • Every Step 1 system

    Written the same way: what to know, how it’s tested, where to go deeper.

  • A plan built to your exam date

    Tell us when you sit, and the schedule fits the whole library and your question bank to it.

  • Flashcards for every page

    Ready-made spaced-repetition decks linked to each topic, so nothing you read gets forgotten.

Start 14 days free
No card needed.·See pricing