Pacing maneuvers in Supraventricular Tachycardia

Raja Selvaraj
Professor of Cardiology
JIPMER

Objectives

• Learn about the types of supraventricular tachycardia seen in the electrophysiology lab
• Learn about the different pacing maneuvers and how to perform them
• Understand the responses to the pacing maneuvers and how these help identify the tachycardia mechanism

General suggestions

Familiarity with EP system and stimulator

• Setting up amplifier / page display / trigger modes
• Learn to make measurements
• Learn to review studies
• Stimulator settings
• Setting up sync for stimulator

When to perform pacing maneuvers

• May not be needed in 85% of SVTs
• Still worth doing each time, especially early in career
• Wider applicability

Understanding and not rote

• Underlying principles - single principle to multiple maneuvers
• Visualise
• Learn by analogy
• Apply principles in reverse

SVT - What are we discussing ?

SVT

• Narrow QRS, can be wide
• "Normal" HV interval
• Typical AVNRT, orthodromic AVRT, AT

AV relationship

Patterns

• More A than V
• More V than A
• A = V
  • Atrial activation sequence
  • VA interval

Pattern 1 - Central A with very short VA

Why is VA short in AVNRT ?

Pattern 2 - Eccentric A

Pattern 3 - Central A, longer VA

Before pacing

Spontaneous termination

Spontaneous termination - Rules

• Tachycardia originating in one chamber will terminate at last activated chamber
• Reentrant tachycardia will terminate with block in any critical limb

Spontaneous termination with V

Spontaneous termination with His

Wobble

Who is married to whom ?

Wobble

Bundle branch block - Coumel

Coumel's sign

Transient finding

Revisiting …

Philip Coumel

Coumel in reverse

Single pacing maneuver

If you are allowed a single pacing maneuver only, what would you do ?

Single useful maneuver

• Central, short VA - AVNRT or AT
• Eccentric VA - AVRT or AT
• Central, longer VA - AVNRT, AVRT or AT

VOP - Setting up

• 20 to 30 ms shorter than tachycardia CL
• Sync on

Stepwise approach

• Was the atrium entrained ?
• Which is the last entrained A ?
• What is the return response - VAV vs VAAV
• What is the cPPI-TCL ? (VAV)
• What is the SA-VA (VAV)

Tachycardia continues

Also useful in eccentric VA conduction

Eccentric conduction

VAAV

Why measure ?

AVRT or AVNRT ? - cPPI-TCL

PPI as measure of distance from circuit

SA-VA

VAV - AVNRT or AVRT ?

Ambiguous measurements

Basal position of RV catheter

Termination during VOP - What now ?

Onset of VOP

Middle of VOP

Entrainment with antegrade His

Termination during VOP

Unable to entrain - What now ?

Unable to entrain

• Accessory pathway ruled out
• Isoprenaline and retry
• Atrial pacing

Other maneuvers

PVCs during tachycardia

His refractory PVC preexcites A

When is a PVC His refractory ?

When is a PVC His refractory

• Occurs after the His signal
• Before the His signal, but interval not sufficient to travel to His
• Does not alter timing of His signal
• Does not change the sequence of His activation
• Manifest fusion

His refractory PVC terminates tachycardia

His refractory PVC in long RP tachycardia

Through the looking glass - PAC in wide QRS tachycardia

Rarely used and advanced maneuvers

• VA linking
• PAC during short VA tachycardia
• Delta AH in long RP tachycardia
• Simultaneous AV pacing

Recap

• Understand the principles
• Practice performing maneuvers and making the measurements
• Ventricular overdrive pacing single most useful maneuver
• Extract most out of this
• PVCs during tachycardia next most important
• Evaluation in sinus rhythm very important (not covered)