Elsevier

Computers in Biology and Medicine

Volume 102, 1 November 2018, Pages 421-425
Computers in Biology and Medicine

A novel method for the prediction of focal wavefront origins in cardiac arrhythmias

https://doi.org/10.1016/j.compbiomed.2018.08.019Get rights and content

Abstract

Background

Current techniques for mapping and ablating cardiac arrhythmias are valuable, but have limitations. We devised a novel method of predicting the origin of a focal arrhythmia wavefront that utilizes conduction velocity (CV), the difference in electrogram timing during arrhythmia (t), and the distance between two points (z) to generate prediction curves which can be applied to an electroanatomic map. The intersection of two such curves predicts the origin of the wavefront.

Objective

To describe the rationale behind a novel method of arrhythmia mapping and assess its feasibility in a retrospective study of focal arrhythmias.

Methods

We retrospectively studied 12 patients with arrhythmias with focal chamber activation that were successfully mapped and treated with ablation. CV during arrhythmia was measured using electroanatomic mapping software. Values for z and t were calculated for two pairs of points. Two prediction curves were generated and superimposed onto the electroanatomic maps. The distance between the intersection of the two curves and the wavefront origin was recorded. The shortest distance between individual curves and the wavefront origin was also measured.

Results

Twenty-four curves were successfully generated in 12 patients. The distance from the intersection of two curves and the wavefront origin was 9.2 ± 7.7 mm. The shortest distance between individual prediction curves and the wavefront origin was 5.2 ± 5.2 mm.

Conclusions

Wavefront origins may be predicted by a novel method utilizing a limited number of measurements. Further study of this method requires its integration with an electroanatomical mapping system.

Introduction

Cardiac arrhythmias are common and cause a substantial burden of symptoms and morbidity, and catheter ablation has become a commonly utilized treatment [1].

Three-dimensional electroanatomic mapping (EAM) was developed to aid in the mapping and ablation of complex arrhythmias. EAM is performed using a computer system that records serial measurements of local cardiac activation relative to a fixed fiducial point, and the location of those measurements in space [2]. With a sufficient number of measurements, a three-dimensional reproduction of the chamber anatomy can be produced, upon which activation data can be plotted. Information obtained about the magnitude of the voltage recorded at each site may provide information about potential arrhythmia substrate.

In this method, the creation of a usable map requires 1) a fiducial electrogram (EGM) with a stable location and morphology 2) a sampled EGM that has a discreet activation for unambiguous annotation 3) persistence of the arrhythmia with a stable cycle length and 4) time to create a map of sufficient resolution.

While this approach works for many patients, a substantial number may have multiple and/or transient arrhythmias that do not lend themselves easily to conventional mapping. Other patients may have abnormal substrate with EGMs that may be diffuse and low-voltage (Fig. 1), hampering the accurate annotation of local activation time.

We sought to develop a new method of mapping arrhythmias that might overcome some of these limitations. We postulated that the origin of focal arrhythmia wavefronts could be mathematically extrapolated based on the relative timing of recorded EGMs during arrhythmia, the distance between them, and a measurement of conduction velocity (CV). In this report, we describe the derivation of the extrapolation formula and its accuracy in a retrospective feasibility study.

Section snippets

Derivation of prediction formula

The derivation of the prediction formula is as follows. Consider two recording bipoles (A and B) located in a cardiac chamber during an arrhythmia of focal origin (Fig. 2). The relative EGM activation recorded at A and B will depend on the location of the wavefront origin (O) with respect to the two bipoles. In Fig. 2A, A and B measure simultaneous activation. This situation could be seen if the origin if the tachycardia was located directly between, equidistant above, or equidistant below A

Results

Twelve tachycardias were studied in 12 patients. Patient and rhythm characteristics are given in Table 1. Wavefront activation initiated in the atrium in 5 patients and in the ventricles in 7 patients. Three patients had orthodromic reciprocating tachycardias utilizing accessory pathways. Although these arrhythmias are reentrant, these patients were included because activation from the perspective of the chamber mapped proceeds from a focal origin located at the site of the accessory pathway.

Discussion

We propose a novel method of mapping arrhythmia wavefront origins that uses a limited number of easily obtained measurements and was successfully implemented in an initial feasibility study.

This method overcomes some of the limitations of conventional mapping. Stability of neither the fiducial point morphology nor the arrhythmia cycle length is required. Prediction curves may be generated in a limited period of time, allowing for the mapping of short-lived or unstable rhythms. While

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of interest

None of the authors report any relevant conflict of interest related to the work submitted.

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1

Present Address: Columbia University College of Physicians and Surgeons 622 W 168th Street, New York, NY 10032.

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