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Novel Techniques for the Identification of the Site of Origin of Ventricular Tachycardia: Part II Magdi M. Saba, MD St. George’s Hospital and University.

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Presentation on theme: "Novel Techniques for the Identification of the Site of Origin of Ventricular Tachycardia: Part II Magdi M. Saba, MD St. George’s Hospital and University."— Presentation transcript:

1 Novel Techniques for the Identification of the Site of Origin of Ventricular Tachycardia: Part II Magdi M. Saba, MD St. George’s Hospital and University of London, UK University of Maryland, Baltimore, MD, USA

2 When there is no match, there is no current process for determining where to stimulate next Prolonged procedures when faced with multiple unstable VTs Pace-Mapping

3 Existing Matching Technology Paced QRS VT QRS template Matching software – provides a numerical output based on degree of morphologic similarity between the VT QRS template and the paced QRS; does not take into account the 3D location of pacing site

4 Concept ECG data obtained from pacing at a series of known locations is used to infer the unknown VT SO By knowing the locations (input) of multiple paced vectors (output), then we should be able to derive the VT SO (input) when we supply the system with the induced VT template/vector (output)

5 Step 1: acquire 3D EAM (or pre-procedural image) ventricle scar

6 Step 2: Pace at 4 to 5 locations, record a surface ECG from each site Step 3: Induce VT and record an ECG

7 Step 4: Integrate data from PM sites (3D location and QRS vector) with VT QRS vector – receive output as a “VTSO area”

8 Step 5: repeat Steps 2,3 and 4 on a limited scale around/in “VTSO area”

9 Step 6: arrive at VTSO, ablate

10

11 E 12 = 1.4864 mVE 12 = 9.1754 mV

12 PatientChamberR2R2 Points, n 1 RV0.820916 LV0.618115 2 LV0.68137 3 LV0.81607 4 RV0.76118 LV0.82515 5 LV0.62699 6 LV0.73448 7 LV0.72827 8 LV0.95627 9 LV0.444023 10 LV0.586910 11 RV0.74326 12 RV0.912711 Correlation: distance / E 12 mean 0.73, in a mixed group of patients and pacing from voltage map- defined normal tissue Data from first 12 patients

13 Results We applied this to a data set with 7 PM points in the LV A single PM was arbitrarily set as the Test PM point (serving as a surrogate for a VT SO) to test for feasibility and accuracy Sets of 3 PM points were used to determine the physical 3D location of the Test PM point

14 Prediction of the 3D location of a PM point using only its ECG data and ECG + Location data from other points Saba M, et al. Prediction of the 3D Location of a Pacing Site from Other Pacing Sites: Experimental Method to Identify the Site of Origin of Ventricular Tachycardia. Heart Rhythm 2009;6(5S):S353.

15 The Test PM point is not used in the prediction model, but its location is successfully predicted by its ECG output relative to the other known Reference PM sites Testing all the PM points as reference points in all 20 combinations, the PM reference point fell within or was on the boundary of the predicted target region 15.71 ± 1.38 times (78.6% first iteration predictive accuracy)

16 PM 10 PM 3 PM 11

17 3D location of PM 9 Predicted

18 Test Case Step 1 Select 3 widely spaced points Spherical Method Surface Distance Method Third point on other side (not visible) Test PM

19 Test Case Step 2 Select new PM point closer to red and replace point furthest from red Spherical Method Surface Distance Method Using Identical PM Points Test PM

20 Test Case Step 3 Repeat step 2 - Select new PM point closer to red and replace point furthest from red

21 Conclusions Higher detail in our understanding of substrate and a more rapid method of identifying the likely VT SO or exit site will lead to improved control of ventricular arrhythmias Issues to resolve with pacemapping: size of electrode tip, HPS capture, scar (what defines it) Prospective, comparative clinical data examining the utility of these novel techniques are required

22 With Thanks The Fischell Department of Bioengineering Keith Herold Jerry Wierwille Joe Davis Stephen Shorofsky Timm Dickfeld Martha McLane


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