Goals 2/10/2016. Voltage Gradient Mapping: A Novel Approach for Successful Ablation of AV Nodal Reentry Tachycardia

Transcription

1 Voltage Gradient Mapping: A Novel Approach for Successful Ablation of AV Nodal Reentry Tachycardia Steven J. Bailin*, MD ; FACC, FHRS Iowa Heart Center, Des Moines, IA University of Iowa Hospital and Clinics, Iowa City, IA * Proprietary Interest in VGM Goals General Context for Voltage Gradient Mapping: Identifying Cardiac Substrate Application in AVNRT Ablation Understanding the mechanism for dual AV Nodal physiology 1

2 Intra Cardiac Recording AH Interval Adapted from Taiwan Rhythm Society Decremental Conduction: AH Interval Adapted from Taiwan Rhythm Society 2

3 Normal AV Nodal Conduction Adapted from Taiwan Rhythm Society Dual AV Nodal Physiology Dual AV Nodal Curve Adapted from Taiwan Rhythm Society 3

4 AV Nodal Anatomy Adapted from Taiwan Rhythm Society AV Nodal Reentry Adapted from Taiwan Rhythm Society AVNRT Current techniques involve a combination of anatomic and electrophysiologic characteristics Most usually, the catheter is placed above the CS Os along the margin of the tricuspid valve, recording a large V>A If unsuccessful, the catheter is typically moved superior toward the region of the AV Node. 4

5 Voltage Gradient Mapping: Defining the Highway Defines tissue substrate by evaluating small variances in endocardial voltage Is not scar mapping Appears to be capable of predicting regions critical for tissue conduction Appears to be universal and represents a paradigm shift in arrhythmia mapping Voltage Gradient Mapping: Technique The high voltage slider was adjusted dynamically to identify high voltage regions The low voltage slider was adjusted dynamically to reveal low voltage bridges within the atrial septum Voltage data below the low voltage value is grey Voltage data between the low voltage and the high voltage values are red and yellow Voltage data above the high voltage value is displayed as purple Data points were reviewed to confirm the validity of the recorded data and exclude pre mature atrial, junctional, or ventricular beats. Understanding Arrhythmias: Utility of VGM Rapid Visual Representation of Endocardial Substrate Rapid Identification of Critical Regions for Conduction (Low Voltage Bridge) Easily Convertible to Propagation Understanding AV Nodal function and providing an explanation of Dual AV Nodal Physiology Easily Integrated into Classical EP Study: Entrainment, Activation Timing, Mid-Diastolic Potentials As a hypothesis, VGM is testable experimentally 5

6 University of Minnesota (circa 1991) VGM Build 6

7 Anatomy Results The slow pathway was identified in all 29 patients via its corresponding low voltage bridge. Low voltage bridges were not observed in patients without dual AV nodal physiology. Ablation of the slow pathway associated low voltage bridges in 29 patients with tachycardia was successful. Repeat mapping confirmed the absence of low voltage connections previously observed in all 29 patients. Results Average number of maps created : 2.8 Mean surface point density was 3.9 points/cm 2 Total data points collected was 214 with an average of 37.8 that projected on Koch s Triangle Average Low voltage setting was 0.197mV ( range mv) 7

8 Results First lesion success was 90% (Cryo ablation termination within 20 secs) Complete Slow pathway ablation was observed in 94% (Isolated non reproducible AV Nodal ECHOs were noted in 6%) Atypical AVNRT required more lesions and multiple slow pathways were observed Type I and Type II No Slow Pathway 8

9 Evidence that LVB = Slow Pathway Residual Slow Pathway 9

10 Conclusions: AVNRT VGM can identify the slow pathway associated LVB Ablation of the LVB terminates AVNRT and results in successful slow pathway ablation VGM can be used to confirm absence of slow pathway LVB following ablation and provides an objective end point for successful AVNRT ablation even in patients without inducible sustained tachycardia Use of VGM permits identification of the SWP in patients with multiple connections or with difficult anatomy AV Nodal Physiology Analysis of propagation and physiologic implications Slow PW Penetration Fast Pathway enters the AV Node Wave Front Collision 10

11 Sinus Rhythm A B Anatomy of an AH Jump Fast Pathway Block Slow Pathway Conduction Into the AV Node D E AVNRT Fast Retrograde blocks in the SPW LVB Slow Antegrade Conducts to the AV Node 11

12 Conclusions 1. Voltage Gradient Mapping is a powerful tool for visualizing the slow pathway 1. The interaction between the fast and slow pathway can be observed and understood 1. Targeting the Low Voltage Bridge results in greater safety and high rates of success 1. In patients without inducible AVNRT, VGM allows high confidence for success 1. Absence of the slow pathway associated LVB predicts successful ablation outcome and provides an objective end point. 12