Quantifying QRS changes during myocardial ischemia: Insights from high frequency electrocardiography

Intra-QRS spectral changes accompany ST segment changes during episodes of myocardial ischemia

“…Reduction of higher frequency components within the QRS, as previously reported[12], may reflect slowed conduction velocity in ischemic myocardium which masks the contribution of wavefront fractionation within the QRS complex. It is reasonable to consider that our CWT-based analysis is able to detect emergence of new potentials in the 24–80 Hz range due to wavefront fractionation, whereas HFQRS analysis is sensitive to the abolition of higher frequency components that may occur due to reduced conduction velocity in the neighborhood of the ischemic region.…”

“…Importantly, the frequency band examined in our study differs markedly from prior studies using HFQRS analysis, which involves higher frequencies of up to 250 Hz[6, 12] . It is reasonable to consider that the type of analysis presented here could be complementary to HFQRS analysis, and the directionality of passband component changes may be different (see discussion below).…”

“…Changes in this range have been demonstrated in various models of ischemia in preclinical and clinical settings[4–11]. However, the mode of detection, magnitude, direction, and frequency range of these changes have varied widely depending on the experimental and clinical conditions, with much attention devoted to the diminution of potentials seen using HFQRS analysis (in the range above 140 Hz)[12]. …”

High resolution ECG-aided early prognostic model for comatose survivors of out of hospital cardiac arrest

“…Peak high frequency QRS amplitude emerged as part of the best combination of 2 variables for normothermic outcome prediction. Similar to QRS-upslope, decreased high frequency QRS amplitude has previously been shown to be associated with acute myocardial ischemia, and also with acute and remote myocardial infarction [29]. Most patients with primary OHCA have ischemic heart disease, and reduced high frequency QRS amplitude probably reflects extent of myocardial damage and is thus related to prognosis.…”

Blinded Analysis of an Exercise ECG Database Using High Frequency QRS Analysis

“…Although most of the conventional diagnostic information of the ECG is contained below 100 Hz in adults, it has long been recognized that higher-frequency components of the QRS complex (as high as 500 Hz) may have clinical significance in patients with various forms of heart disease [3]. However, the current standard for diagnostic devices recommends a cutoff frequency of 150 Hz for the analog filter [1].…”