High-frequency components in ECG analysed in guinea-pig Langendorf preparations

High-frequency QRS electrocardiogram

The standard 12-lead electrocardiogram (ECG) is one of the most commonly used methods for diagnosing heart disease. Standard ECG is not always optimal, however, and new ECG methods can provide additional information. Analysis of high-frequency QRS components (HF-QRS) has been shown to increase the diagnostic performance of the ECG. Several investigators have studied HF-QRS in different cardiac conditions, including acute myocardial ischaemia and myocardial infarction, but more knowledge is needed about the characteristics of HF-QRS before clinicians can use it as an adjunct to standard ECG.

High-frequency electrocardiogram analysis in the ability to predict reversible perfusion defects during adenosine myocardial perfusion imaging

BACKGROUND

A previous study has shown that analysis of high-frequency QRS components (HF-QRS) is highly sensitive and reasonably specific for detecting reversible perfusion defects on adenosine myocardial perfusion imaging (MPI) scans. The purpose of the present study was to try to reproduce those findings.

METHODS

Twelve-lead high-resolution electrocardiogram recordings were obtained from 100 patients before (baseline) and during adenosine (99m)Tc-tetrofosmin MPI tests. The HF-QRS were analyzed regarding morphology and changes in root mean square voltages from before the adenosine infusion to peak infusion.

RESULTS

The best area under the curve (AUC) was found in supine patients (AUC = 0.736) in a combination of morphology and root mean square changes. None of the measurements, however, were statistically better than tossing a coin (AUC = 0.5).

CONCLUSION

Analysis of HF-QRS was not significantly better than tossing a coin for determining reversible perfusion defects on MPI scans.

Reduced high-frequency QRS components in electrocardiogram leads facing an area of the heart with intraventricular conduction delay due to bundle branch block

BACKGROUND

The mechanisms underlying high-frequency QRS components (HF-QRS) are incompletely understood. One theory is that HF-QRS are related to the conduction velocity of the heart. The purpose was to test this hypothesis by comparing HF-QRS in patients with left or right bundle branch block (LBBB and RBBB, respectively) to those in healthy subjects and in patients with ischemic heart disease (IHD).

METHODS

Twenty-two patients with LBBB, 19 patients with RBBB, 63 normal subjects, and 64 patients with IHD were included. Twelve-lead electrocardiograms were analyzed in the frequency interval 150 to 250 Hz.

RESULTS

The study showed reduced HF-QRS in patients with LBBB compared with healthy subjects and patients with IHD. The difference, however, was small in lead V(1) and V(2). In patients with RBBB, no differences in HF-QRS could be detected except in few leads; among those is lead V(1).

CONCLUSION

The results support the theory that HF-QRS are related to the conduction velocity of the heart.