Verapamil-Sensitive Left Ventricular Tachycardia

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Contents 1 Chracteristics 2 Subgroups 3 Mechanism 4 Endocardial Mapping 5 Ablation 6 After Successful Ablation 7 References 8 Articles

Chracteristics

1. Induction with atrial pacing
2. RBBB with LAD
3. Manifestation in patients without structural heart disease
4. Verapamil sensitive
   1. Using Verapamil 1.5mg IV significantly prolongs the VT cycle length and P1-P2 intervals
5. Most common form of Idiopathic Left Ventricular Tachycardia

Subgroups

1. Left Posterior Fascicular (RBBB and Superior Axis)
   1. Most Common
2. Left Anterior Fascicular (RBBB and Right Axis Deviation)
   1. Uncommon
3. Upper Septal Fascicular VT (Narrow QRS and normal or RAD)
   1. Very Rare

Mechanism

• P1 represents the activation potential in the distal portion of the specialized Purkinje tissue, and has decremental properties and is verapamil sensitive.
• P2 represents the activation potential of the left posterior fascicle or the Purkinje fibers near the left posterior fascicle.
• During Sinus the activation goes from P2 to P1 at the point of fusion; therefor P1 is buried in the local electrogram
• During VT, P1 and P2 activate in the reverse direction

Endocardial Mapping

• Place an octapolar steerable catheter at the interventricular septum
• In the Double Potential Group you are able to record two distinct potentials (P1 and P2) at the mid-septum
  • P1 is recorded earlier from the proximal to distal electrodes
  • P2 is recorded earlier from the distal than the proximal electrodes
• In the Single Potential Group when only P2 can be recorded
  • Only a single fused Purkinje Potential is recorded at the middle or inferior apical septum
  • Pacing from the successful ablation site produces a similiar QRS configuration to that of the VT, and the PPI-VT CL difference is within 30 ms.

Ablation

1. Target P1 Potential at apical 1/3 of septum.
   1. Do not ablate at earliest P1 potential because that site may be too proximal resulting in AV Block or LBBB.
   2. The interval between P1 at the successful site of ablation and the onset of the QRS complex (P1-QRS interval) during VT was 60ms +/- 29ms.
   3. Pacing from this site with not result in a perfect pace map, however the PPI to VT CL difference is within 30 msec
2. Target the earliest Presystolic Purkinje potential (P2) at VT exit if P1 can not be recorded
3. Use Pace Mapping
4. Perform anatomic linear ablation to transect the middle to distal left fascicular tract

After Successful Ablation

• In sinus rhythm the P1 will be after the QRS complex while the P2 will be observed before the QRS complex
• After successful ablation the QRS-P! with show decremental properties during atrial and ventricular pacing and with the administration of verapamil.

References

1. Demonstration of diastolic and presystolic Purkinje potentials as critical potentials in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia. J Am Coll Cardiol. 2000 Sep;36(3):811-23.

Articles

Image:IdiopathicVT.pdf

Lerman, BB, et al. "Ventricular Tachycardia in Patients with Structurally Normal Hearts" from "Cardiac electrophysiology: from cell to bedside" Zipes, Jalife, 4th ed.

     Excellent review of the mechanism of verapamil-sensitive fascicular tachycardia.

Maruyama M, Tadera T, Miyamoto S, et al: "Demonstration of the reentrant circuit of verapamil-sensitive idiopathic left ventricular tachycardia: Direct evidence for macroreentry as the underlying mechanism." J Cardiovasc Electrophysiol 12:968-972, 2001.

Nogami A, Naito S, Toda H, et al: "Demonstration of diastolic and presystolic Purkinje potentials as critical potentials in a macrorentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia." J Am Coll Cardiol 36:811-823, 2000.