1. Gadolinium Enhances Radiofrequency Ablation
Duy T Nguyen, MD, FHRS1, Joshua D Moss, MD, FHRS2, Waseem Y Barham, MD, MBBS1,
Lijun Zheng, MS1, Robert A Quaife, MD1, and William H Sauer, MD, FHRS1
1University of Colorado, 2University of Chicago
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BACKGROUND
RESULTS
Delivery of radiofrequency (RF) energy to create cardiac ablation lesions can be facilitated by direct intra-myocardial injection of electrically and thermally conducting material, as we have previously demonstrated in an ex vivo model.
We next sought to characterize the effects of myocardial infiltration with chelated gadolinium (gado) -- a commonly used metal in medical procedures -- on RF ablation in an in vivo porcine model.
Ex vivo ablation with gado resulted in larger lesions, higher temperatures and larger impedance drops (Figures 2 and 3).
In vivo gado infiltration (A) resulted in significantly larger lesions compared to saline (B), 592 ml vs. 102 ml (P<0.001).
Nearly transmural lesions were achieved with 50 W irrigated ablations on gado-infiltrated myocardium (figure 4).
METHODS
Yorkshire pigs were anesthetized and the left ventricle (LV) was accessed.
An LV electroanatomic map was created (Figure 1).
Prior to ablation, 1 mL of gado (gadoteridol; Prohance) or saline was injected 5 mm into the myocardium using an endovascular catheter with a retractable needle (Myostar, Biosense- Webster).
Endocardial ablations were delivered at 50W for 30 seconds with the same force as measured by a force-sensing irrigated tip catheter.
Animals were sacrificed and lesion analyses were performed.
In vivo experiments were correlated to ex vivo ablation with gado on bovine myocardium.
Figure 4. In vivo ablation of the left ventricle after endocardial gado injection (A) resulted in significantly larger lesions (arrow) compared to lesions (arrow) from ablation of saline-treated myocardium (B). The dark ring surrounding lesions in each panel represents borderzone erythema of the necrotic lesion.
CONCLUSIONS
In our porcine model, endocardial infiltration of myocardial tissue with chelated gadolinium produced significantly larger ablation lesions, compared to saline infiltration.
Our findings have clinical implications for ablation procedures incorporating gadolinium.
Because gadolinium has been used safely in humans, its use as a facilitating agent for RF ablation should be further evaluated.
Figure 2. Mean starting and ending impedances in untreated controls, saline-infiltrated controls, and gadolinium treated myocardial tissue before and after ablation.
Figure 1. Electroanatomic map of the LV endocardium after in vivo ablation in posteroanterior projection. Prior to ablation, saline (yellow lesion tags) or gadolinium (blue lesion tags) was injected at the sites annotated on the map. The ablation catheter was then positioned at these sites for delivery of radiofrequency ablation (red lesion tags).
W.H. Sauer disclosures A - Consulting Fees/Honoraria; 1; Boston Scientific Corp.. I - Research Grants; 4; Biosense Webster, Inc.. J - Fellowship Support; 3; Boston Scientific Corp., Biosense Webster, Inc., Medtronic, Inc., St. Jude Medical
Figure 3. Mean temperature dispersion at 3 and 5 mm depths in gadolinium treated myocardium, compared to untreated controls and saline controls at 50 W.