The Accuracy of Cardiac Surface Conduction Velocity Measurements

Conduction velocity (CV) is a measure of the health of myocardial tissue. It can be measured by taking differences in local activation times from intracardiac electrodes. Several factors introduce error into the measurement, among which ignoring the 3-dimensional aspect is a major detriment.

The purpose of this study was to determine if, nonetheless, there was a specific region where CV could be accurately measured.

Computer simulations of 3-dimensional ventricles with a realistic His-Purkinje system were performed. Ventricles also included a dense scar or diffuse fibrosis.

A finer spatial sampling produced better agreement with true CV. Using an error limit of 10 cm/s as a threshold, measurements taken within a region <2 cm from the pacing site proved to be accurate. Error increased abruptly beyond this distance. The Purkinje system and tissue fiber orientation played equally major roles in leading to a surface CV that was not reflective of the CV propagation through the tissue.

In general, surface CV correlates poorly with tissue CV. Only surface CV measurements close to the pacing site, taken with an electrode spacing of ≤1 mm, give reasonable estimates.