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Implantable Cardioverter Defibrillator Lead Tip as a Surrogate Fiducial for Non-Invasive Cardiac Radioablation in the Treatment of Ventricular Tachycardia

P Samson*, D Anand, S Goddu, M Prusator, D Yang, N Knutson, J Park, P Cuculich, C Robinson, G Hugo, Washington University, St. Louis, MO


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: As non-invasive cardiac radioablation becomes increasingly implemented, a challenge is establishing a reliable method to account for target motion. Since nearly all ventricular tachycardia patients have implantable cardioverter defibrillators (ICDs), it may be possible to use the lead tip as a fiducial. However, the range of movement of these lead tips is unknown.

Methods: The 4D-CT simulation studies from 6 patients were reviewed to quantify right ventricular lead tip movement. The lead tip was manually segmented from the cone beam CT and a model generated. This was used as a template to measure lead tip position in each projection to estimate the 3D trajectory. High and low pass filters with a cutoff frequency of 0.6 Hz were used to extract the cardiac and respiratory components. The range of motion and average amplitude (peak to trough) were measured for cardiac and respiratory motion components independently and for overall motion.

Results: In this analysis, the mean cardiac range in the lateral (LR), anterior-posterior (AP), and superior-inferior (SI) orientations was 10.2mm, 5.8mm, and 9.9mm, respectively. The mean respiratory range in LR orientation was 5.8mm, AP 3.6mm, and SI 7.3mm. The overall mean range was 12.9mm LR, 7.8mm AP, and 13.9 SI. The mean cardiac amplitude was LR 4.7mm, AP 2.3mm, and SI 4.48mm. The mean respiratory amplitude values were LR 3.2mm, AP 1.7mm, and SI 3.9mm. Overall mean amplitude was LR 5.2mm, AP 2.6, and SI 5.2mm. The mean ejection fraction (EF) was 30% (normal heart function >55%) and there was a negative correlation between increasing EF and cardiac LR range (-0.87, p=0.02).

Conclusion: ICD lead tips as a surrogate fiducial show substantial 3D variation in range and amplitude. At this time, the hemodynamics of lead tip movement in the right ventricle may not be an appropriate surrogate for left ventricular targets.


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