Introduction to High-Resolution Cardiac Mapping

Invasive cardiac mapping systems are used to develop 3-D computer models of the patient's heart, complete with electrogram (EGM) voltages and activation timing. The model can then be used to determine target areas for ablation.

These systems rely on a catheter that is inserted through blood vessels and navigated to the heart, where it records EGMs. Catheters may be designed for either contact or noncontact mapping. Contact mapping requires the electrodes on the catheter to physically touch the heart wall; noncontact mapping is performed when the catheter is centered within the chamber to be mapped.

In recent years, manufacturers have begun to advertise high-resolution mapping as one of the advantages of their systems. What does it mean when they say this, and how do systems differ? Does high-resolution mapping offer clinical benefits? What are the benefits of upgrading to a new system, and which systems should be considered? In this article, we will address these common questions.

Mapping resolution refers to the system's ability to differentiate between adjacent conduction patterns—a system with high resolution can accurately display small features and fine lines, such as small gaps in conduction block. This is also commonly referred to as spatial resolution, as opposed to temporal resolution (the ability to resolve events of short time duration). The spatial resolution of a system depends on the size of the electrodes, the interelectrode spacing, the mapping density, the amount of interpolation and averaging performed, and other system characteristics.

1. Small electrode size contributes to visualization of small structures, much as a small pixel size contributes to a clear video image. The electrode captures signals over its entire surface, recording the average signal (Stinnett-Donnelly et al. 2012). If the voltage is high on one side of the electrode and low on the other side, the electrode will record a signal somewhere in the middle. Larger electrodes average over a larger...