HEMODYNAMIC EVALUATION OF THE HEART WITH A NONFLUOROSCOPIC ELECTROMECHANICAL MAPPING TECHNIQUE

Background Clinical cardiac volumetric measurement techniques are esse ntial for assessing cardiac performance but produce significant inaccu racies in extrapolation of the volume of a three-dimensional (3D) obje ct from two-dimensional images, and lack the ability to associate card iac electrical and mechanical activities. In this study, we tested the accuracy of cardiac volumetric measurements using a new catheter-base d system. Methods and Results The system uses magnetic technology to a ccurately locate a special catheter at a frequency of 125 Hz and is cu rrently used in the field of electrophysiology, in which activation ma ps are superimposed on the 3D geometry of the cardiac chamber. The map ping procedure is based on sequentially acquiring the location of the tip and local electrogram while in contact with the endocardium. The 3 D geometry of the chamber is reconstructed in real time, and its volum e could be calculated at every time step (8 ms). The volumetric measur ements of the system were found to be highly accurate for simple phant oms (mean +/- SEM deviation, 2.3 +/- 1.1%), left ventricular casts (9. 6 +/- 1.3%), and a dynamic test jig. In addition, left ventricular vol umes of 12 swine were measured. Intraobserver and interobserver variab ilities were found to be minimal (ejection fraction, 6.5 +/- 1.9% and 7.1 +/- 2.0%; stroke volume, 4.5 +/- 1.0% and 11.3 +/- 2.4%). Comparis on with the thermodilution method for measuring stroke volume showed a n average deviation of 8.1 +/- 2.2%. Typical pressure-volume loops wer e also obtained. Conclusions The new mapping image provides, for the f irst time, simultaneous information regarding cardiac mechanics, hemod ynamics, and electrical properties. Furthermore, all this information is achieved without the use of fluoroscopy, contrast medium, or compli cated image processing.