The Effect of 40 Hz Low-Pass Filtering on the Magnitude of the Spatial Ventricular Gradient

Daniel Guldenring1, Dewar Finlay2, Alan Kennedy3, Raymond Bond2, Michael Jennings2, James McLaughlin2
1HTW Berlin, 2Ulster University, 3University of Ulster


Abstract

The spatial ventricular gradient (SVG) is a vectorcardiographic (VCG) parameter. The SVG is typically obtained form VCG data that is derived from the 150 Hz low-pass filtered resting 12-lead electrocardiogram (ECG). The magnitude of the SVG is sensitive to changes in the ventricular repolarisation heterogeneity. Increased ventricular repolarisation heterogeneity has been shown to be associated with an increased risk of ventricular arrhythmias. The sensitivity of the SVG to changes in the ventricular repolarisation heterogeneity makes the utilisation of the SVG potentially attractive for 12-lead ECG monitoring applications. However, 12-lead monitoring ECGs are typically filtered using a low-pass filter with a cut-off frequency of 40 Hz. Whether the utilization of 40 Hz low-pass monitoring ECG filters over the commonly used 150 Hz low-pass resting ECG filters does have an effect on the value of the SVG magnitude has not previously been reported. The aim of this research was to quantify the differences between the magnitude of the SVG computed using 40 Hz low-pass filtered ECG data (SVG40) and the magnitude of the SVG computed using 150 Hz low-pass filtered ECG data (SVG150). We assessed the difference between the SVG40 and the SVG150 using a study population of 726 subjects. The differences between the SVG40 and the SVG150 were quantified as systematic error (mean difference) and random error (span of Bland-Altman 95% limits of agreement). The systematic error between the SVG40 and the SVG150 was found to be 0.013 mV ms [95% confidence interval: 0.008 mV ms to 0.018 mV ms]. The random error was quantified as 0.072 mV ms [95% confidence interval: 0.266 mV ms to 0.298 mV ms]. The findings of our research suggest that it is possible to record the magnitude of the SVG in applications that require the utilization of 40 Hz low-pass ECG monitoring filters.