Direction-aware mapping algorithms have minimal impact on bipolar voltage maps created using high-resolution multielectrode catheters.

INTRODUCTION: Direction-aware mapping algorithms improve the accuracy of voltage mapping by measuring the maximal voltage amplitude recorded in the direction of wavefront propagation. While beneficial for stationary catheters, its utility for roving catheters collecting electrograms (EGMs) at multiple angles is unknown. OBJECTIVE: To compare the directional dependence of bipolar voltage amplitude between stationary and roving catheters. METHODS: In 10 swine, a transcaval ablation line with a gap was created. The gap was mapped using an array catheter (Optrell™; Biosense Webster). In Step 1, the array was kept stationary over the gap, and four voltage maps were created during activation of the gap from superior, inferior, septal, and lateral directions. In Step 2, four additional maps were created; however, the catheter was allowed to move with points acquired at multiple angles. In Step 3, the gap was remapped; however, bipoles were computed using a direction-aware mapping algorithm. RESULTS: In a stationary catheter position, bipolar voltage distribution was influenced by the direction of activation with maximal differences obtained between orthogonal directions 32% (13%-53%). However, roving the catheter produced similar bipolar voltage maps irrespective of the direction of activation 11% (5%-18%). A direction-aware mapping algorithm was beneficial for reducing the directional dependence of voltage maps created by stationary catheters but not by roving catheters. CONCLUSION: The directional dependency of bipolar voltage amplitude is greatest when the catheter is stationary. However, when the catheter is allowed to rove and collect EGMs at multiple angles as occurs clinically, the directional dependence of bipolar voltage is minimal.

High-Resolution Mapping of Ventricular Scar: Evaluation of a Novel Integrated Multielectrode Mapping and Ablation Catheter.

OBJECTIVES: This study sought to evaluate an investigational catheter that incorporates 3 microelectrodes embedded along the circumference of a standard 3.5-mm open-irrigated catheter. BACKGROUND: Mapping resolution is influenced by both electrode size and interelectrode spacing. Multielectrode mapping catheters enhance mapping resolution within scar compared with standard ablation catheters; however, this requires the use of 2 separate catheters for mapping and ablation. METHODS: Six swine with healed infarction and 2 healthy controls underwent mapping of the left ventricle using a THERMOCOOL SMARTTOUCH SF catheter with 3 additional microelectrodes (0.167 mm2) along its circumference (Qdot, Biosense Webster, Diamond Bar, California). Mapping resolution in healthy and scarred tissue was compared between the standard electrodes and microelectrodes using electrogram characteristics, cardiac magnetic resonance, and histology. RESULTS: In healthy myocardium, bipolar voltage amplitude was similar between the standard electrodes and microelectrodes, with a fifth percentile of 1.19 and 1.30 mV, respectively. In healed infarction, the area of low bipolar voltage (defined as <1.5 mV) was smaller with microelectrodes (16.8 cm2 vs. 25.3 cm2; p = 0.033). Specifically, the microelectrodes detected zones of increased bipolar voltage amplitude, with normal electrogram characteristics occurring at the end of or after the QRS, consistent with channels of preserved subendocardium. Identification of surviving subendocardium by the microelectrodes was consistent with cardiac magnetic resonance and histology. The microelectrodes also improved distinction between near-field and far-field electrograms, with more precise identification of scar border zones. CONCLUSIONS: This novel catheter combines high-resolution mapping and radiofrequency ablation with an open-irrigated, tissue contact-sensing technology. It improves scar mapping resolution while limiting the need for and cost associated with the use of a separate mapping catheter.