MEDICAL ENGINEERING & PHYSICS, vol.29, no.9, pp.937-945, 2007 (SCI-Expanded)
Catheter-based epicardial mapping is possible with two access methods: transthoracic pericardial access and transvenous access. Transtho- racic pericardial access is based on the introduction of the catheters into the pericardial space using a percutaneous subxiphoid puncture and may at times require lengthy sequential mapping procedures. From the transthoracic pericardial approach major regions of the epicardium may also be inaccessible. Transvenous access uses the multielectrode (4–20 electrodes) catheters placed in the coronary veins thus increases the speed of the mapping procedure, however, leaves most of the epicardium inaccessible to direct measurement. The aim of this present study is to demonstrate that the reconstruction of the high-resolution maps using sparse measurements from different sites on the epicardium and on the multielectrode catheters is possible with a reasonably high accuracy in terms of locating the origin of the ventricular arrhythmia. In this study we investigated strategies for the reconstruction of epicardial potential distribution from recordings of intravenous and transthoracic epicardial mapping catheters, alone and in combination. For this purpose, we first examined the problem of best number of epicardial measurement sites (or best sampling resolution) using transthoracic mapping catheters and secondly studied the feasibility of the combined usage of both mapping approaches. In the prediction of the surrogate measurements at inaccessible sites from the measurements localized to the cardiac veins and sparse epicardial sites we evaluated two prediction methods: the Laplacian interpolation and statistical estimation, to overcome the sparsity of the measurements. We performed 14 dog experiments with various interventions to create a high-resolution epicardial potential map database. This database included a total of 592 beats which were recorded using a sock array placed on the ventricles of dog hearts. We found that 2 cm sampling resolution is quite feasible, which means that the time for the mapping procedure may be reduced considerably. Predictions from the combination of 21 intravenous catheter leads and 30 transthoracic catheter leads were better than when only 21 or 30 leads were used. The results of this study encourage further investigation and provide adequate evidence that an epicardial mapping approach based on the combined usage of transvenous and transthoracic pericardial access methods for the mapping of the outer surface of the heart is feasible and can provide adequate accuracy for clinical applications.