Optimal configuration of adhesive ECG patches suitable for long-term monitoring of a vectorcardiogram

Abstract

The purpose of this study was to develop optimal configuration of adhesive ECG patches placement on the torso, which would provide the best agreement with the Frank orthogonal ECGs. Ten seconds of orthogonal ECG followed by 3–5 min of ECGs using patches at 5 different locations simultaneously on the torso were recorded in 50 participants at rest in sitting position. Median beat was generated for each ECG and 3 patch ECGs that best correlate with orthogonal ECGs were selected for each participant. For agreement analysis, spatial QRS-T angle, spatial QRS and T vector characteristics, spatial ventricular gradient, roundness, thickness and planarity of vectorcardiographic (VCG) loops were measured. Key VCG parameters showed high agreement in Bland–Altman analysis (spatial QRS-T angle on 3-patch ECG vs. Frank ECG bias 0.3 (95% limits of agreement [−6.23;5.71 degrees]), Lin's concordance coefficient = 0.996). In conclusion, newly developed orthogonal 3-patch ECG can be used for long-term VCG monitoring.

Introduction

Heart disease is the leading cause of death in the United States [1]. The electrocardiogram (ECG) is a widely used non-invasive tool for risk stratification and diagnosis of several cardiovascular diseases. For example, atrial fibrillation (AF) is a common clinical arrhythmia which is estimated to affect 2.7–6.1 million people in the US and is expected to double by 2050 [2]. Long-term ECG monitoring is an important diagnostic tool for asymptomatic and infrequent cardiac arrhythmias. Recently developed, wearable adhesive ECG patches have revolutionized long-term ECG monitoring. Lightweight compact ECG patches are comfortable to wear, therefore reducing barriers to patient compliance. It has been shown that the longer duration of ambulatory ECG monitoring the higher diagnostic yield [3], [4], [5]. However, single lead ECG patch monitoring has obvious limitations: difficulties in discrimination between cardiac beat and artifact, and limited capabilities in diagnosing ischemia or origin of cardiac arrhythmias.

The vectorcardiogram (VCG), which was first constructed in 1920 by Mann [6] and defined in 1938 by Wilson [7], represents movement of heart vector in three orthogonal dimensions. Analysis of VCG can provide complementary information to the 12-lead ECG and has been demonstrated to help define abnormal electrophysiological substrate in patients with life-threatening ventricular arrhythmias and sudden cardiac death (SCD) [8], [9]. Recently we showed that VCG measures of global electrical heterogeneity such as spatial QRS-T angle, sum absolute QRST integral (SAI QRST), and spatial ventricular gradient (SVG) are associated with risk for sudden cardiac death (SCD) [10]. It is well known that the risk of SCD is dynamic. However, previously there were no tools for long-term VCG monitoring.

The BioStamp Research Connect™ (MC10, Inc., Lexington, MA) patch is a newly developed mobile telemetry device for continuous recording of high resolution (up to 1000 Hz) ECG and electromyographic signals, and body movements, based on epidermal electronics technology [11]. The goal of this study was to develop the optimal configuration of patch placement on the torso which would provide the best agreement with the modified Frank orthogonal ECG. We hypothesized that patches placed in locations looking at the heart from three orthogonal axes around the heart's centre would provide an ECG with information similar to the orthogonal ECG.