Effects of Heart Rate and Ventricular Wall Thickness on Non-invasive Mapping: An in silico Study.

Erick Andres Perez Alday,Dominic G Whittaker,Michael A Colman,Alan P Benson

doi:10.3389/fphys.2019.00308

Erick Andres Perez Alday, Dominic G Whittaker + Show 2 more

Open Access

https://doi.org/10.3389/fphys.2019.00308

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Abstract

Background: Non-invasive cardiac mapping—also known as Electrocardiographic imaging (ECGi)—is a novel, painless and relatively economic method to map the electrical activation and repolarization patterns of the heart, providing a valuable tool for early identification and diagnosis of conduction abnormalities and arrhythmias. Moreover, the ability to obtain information on cardiac electrical activity non-invasively using ECGi provides the potential for a priori information to guide invasive surgical procedures, improving success rates, and reducing procedure time.Previous studies have shown the influence of clinical variables, such as heart rate, heart size, endocardial wall, and body composition on surface electrocardiogram (ECG) measurements. The influence of clinical variables on the ECG variability has provided information on cardiovascular control and its abnormalities in various pathologies. However, the effects of such clinical variables on the Body Surface Potential (BSP) and ECGi maps have yet to be systematically investigated.Methods: In this study we investigated the effects of heart size, intracardiac thickness, and heart rate on BSP and ECGi maps using a previously-developed 3D electrophysiologically-detailed ventricles-torso model. The inverse solution was solved using the three different Tikhonov regularization methods.Results: Through comparison of multiple measures of error/accuracy on the ECGi reconstructions, our results showed that using different heart geometries to solve the forward and inverse problems produced a larger estimated focal excitation location. An increase of ~2 mm in the Euclidean distance error was observed for an increase in the heart size. However, the estimation of the location of focal activity was still able to be obtained. Similarly, a Euclidean distance increase was observed when the order of regularization was reduced.For the case of activation maps reconstructed at the same ectopic focus location but different heart rates, an increase in the errors and Euclidean distance was observed when the heart rate was increased.Conclusions: Non-invasive cardiac mapping can still provide useful information about cardiac activation patterns for the cases when a different geometry is used for the inverse problem compared to the one used for the forward solution; rapid pacing rates can induce order-dependent errors in the accuracy of reconstruction.

Highlights

Cardiovascular disease is a major contributor to reduced quality of life and mortality worldwide (Benjamin et al, 2017)
Our results show that the Electrocardiographic imaging (ECGi) approach gives the most accurate results when used with geometries depicting the current state of the patient’s heart, but if a single image of the patient’s heart is obtained, for example at the start of treatment, the ECGi approach still gives useful and reasonably accurate information relating to underlying electrophysiological abnormalities
The Second order regularization approach produced the smallest errors and largest correlation

Summary

Introduction

Cardiovascular disease is a major contributor to reduced quality of life and mortality worldwide (Benjamin et al, 2017). Cardiac conditions such as heart failure, myocardial infarction, and hypertrophic/dilated cardiac myopathy are related to electrical dysfunction (i.e., arrhythmia) and typically result in reduced cardiac output. Non-invasive cardiac mapping— known as Electrocardiographic imaging (ECGi)—is a novel, painless and relatively economic method to map the electrical activation and repolarization patterns of the heart, providing a valuable tool for early identification and diagnosis of conduction abnormalities and arrhythmias. The ability to obtain information on cardiac electrical activity non-invasively using ECGi provides the potential for a priori information to guide invasive surgical procedures, improving success rates, and reducing procedure time. The effects of such clinical variables on the Body Surface Potential (BSP) and ECGi maps have yet to be systematically investigated

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