The Fundamental Investigation Of The Reconstruction Of Endocardium's Model And The Accuracy Of Registration Of The Three-dimensional Navigation And Positioning System

Objective: To acquire three-dimensional reconstruction of right ventricular endocardium with low-frequency current field and to validate the accuracy of registration of the three-dimensional navigation and positioning system in vitro and in vivo respectively.Methods: 1. A scoop-channel is used to validate the accuracy of registration of the navigation and positioning system in vitro. A oblong scoop-channel with isotonic Na chloride and bellows phantom in it, is to simulate the demic electricity characteristic. The electric field excitation output signal is generated by the orthogonal positioned electrodes. Move catheter to make the electrode be in a random spot in the valid range and record space position of the spot(X0,Y0,Z0)in the scoop-channel, meantime make a mark of the navigation electrode as virgin spot in the software.Revolve coordinate staff to make navigation electrode depart the mark. Reposit the navigation electrode with the invariant system to go back the virgin mark, then record actual position(X1,Y1,Z1)in the scoop-channel and calculate the distance between actual spot and the virgin spot in the scoop-channel. Fifteen spots are validated in all. 2. Loading a spatial orthonormal low frequency alternating current field onto the surface of an experimental animal with three standard skin electrodes to creat low-frequency transthoracic orthonormal electrical fields to cover the area of the heart. Then regular catheter electrodes are used as sensors for a low-frequency transthoracic electrical field. Firstly, reconstruct the endocardium of right ventricle. Detain two 7F sheaths through punctured two-side femoral veins, and post in big head electrodes into right atrium and right ventricle respectively. Collect voltage locating signals and obtain positional information of mapping catheter while dragging the catheter along endocardium of the measured chamber. Three-dimensional model of the measured chamber is reconstructed by the computer, when the collected location data are enough. Sencondly, pace the right ventricle at a random spot, record 12-lead synchronous electrocardiogram(ECG) and make the spot as the virgin spot in the software. Depart the catheter electrode from the virgin spot for a few minites, then reposit electrode to the virgin spot by the navigation system. Pace the right ventricle at the same spot once more and record 12-lead synchronous electrocardiogram(ECG) again. Comparing the two ECGs to make sure whether they are completely identical or not to validate the accuracy of registration of the navigation system. Do as above three hours later to validate the stability of the postioning and navigation system.Results: Positioning deviation is 0.82±0.14mm in vitro. The results in vivo:(1)Reconstruction of endocardium's models has some deformation, but all right ventricle model structures are similar. (2)The results of right ventricular pacing ECGs demonstrate that complete identical rate when the electrode is reposited to the virgin spot instantly and complete identical rate when reposited 3 hours after departing from the virgin spot are 100% and 60% respectively. The total complete identical rate is 80%.Conclusions: 1. Electrophysiology recordings are unaffected by the applied electrical field. The technique can be applied to regular catheters and complex catheters such as multielectrode catheters, irrigated electrode catheters, and basket catheters. 2. Although the reconstitution of endocardium's models has some deformation, the accuracy can meet the demand of the valid ablation of the target when radiofrequency catheter ablation. 3. This new technique enables accurate and reproducible real-time localization of electrode positions. 4. Achievement ratio of long term repostion of the system was lower than that of instantly reposition.