Ector J et al. (2005) Cardiac three-dimensional magnetic resonance imaging and fluoroscopy merging: a new approach for electroanatomic mapping to assist catheter ablation. Circulation 112: 3769–3776

The nonfluoroscopic mapping techniques used to assist catheter ablation by generating three-dimensional electroanatomic models of the heart chambers generally require expensive, specialized catheters and hardware. Moreover, anatomic reconstruction is inaccurate, because it is dependent on unviewed catheter navigation.

In an effort to resolve these problems, Ector et al. have developed a system for merging fluoroscopy and three-dimensional models based on MRI. For 39 patients, they constructed anatomical maps of the right atrium before catheter ablation treatment; they did not use gadolinium contrast agent, which can distribute unevenly in tissues, leading to inaccuracies. Contours of endocardial tissue in the heart chambers were delineated manually on the images acquired by use of customized software that enabled contours to be cross-checked against those in other imaging planes. The resulting models were merged with biplane fluoroscopic images during the ablation procedures.

In this pilot study, catheters were reliably positioned in 11 patients, with three-dimensional electroanatomic maps assembled with sufficient anatomical detail to assist ablation. Limitations pointed out by the authors are that real-time catheter tracking is not yet possible and that MRI should also be done at least 1 day before the ablation procedure, which might affect model accuracy. Compared with other electroanatomic mapping systems, however, this new method provides more-detailed anatomical information, permits use of a regular biplane fluoroscopy setup, exposes patients to less radiation, does not require specialized mapping catheters, is potentially cheaper, and can be applied more universally than dedicated systems.