User:Gubon74/draft article on HFQRS

HFQRS refers to the analysis of the high frequency spectral components of the mid QRS complex in an electrocardiogram (ECG).





Traditional exercise ECG testing is based on ST segment analysis, yet with limited diagnostic accuracy particularly in women. Several attempts have been made to expand the diagnostic capabilities of the ECG.

Scientific evidence indicates that identification of depolarization abnormalities, which can be quantified using analysis of high frequency QRS signals, is more accurate in detecting Coronary Ischemia (known as Cardiac Ischemia or Myocardial Ischemia) than identification of ST segment deviations. The physiological significance of the high frequency components of the QRS complex was first described in the 1980’s. Since then, it has been extensively researched and clinically validated as an important diagnostic tool.

HFQRS Scientific background
Conventional ECG interpretation is performed by inspecting the ECG in the 0.05-100 Hz frequency band. Detection of ischemia relies upon recognition of abnormal alterations in the repolarization phase of the cardiac cycle, manifested as changes in the ST segment of the ECG. However, significant research efforts during the last decade have shown that ischemia also induces changes to the depolarization phase. These changes can be detected by examining the high-frequency content of the mid-QRS complex (HFQRS). These high frequency components, resulting from the fragmented waveform of electrical activation of the myocardium, can be filtered from high resolution ECG signals in the 150 to 250 Hz frequency band. As these components are very low in amplitude (measured in µV), sophisticated computer analysis is required to reliably extract them.

Clinical Data
Several studies show that HFQRS performs significantly better than standard ST segment based analysis in detecting myocardial ischemia in stress ECG testing, both in terms of sensitivity and in specificity. HFQRS analysis performs equally well in women, a population in which standard, ST segment based stress ECG analysis, is notoriously inaccurate.

Economics of HFQRS
Coronary Heart Disease (CHD) is a major healthcare problem worldwide, being the leading cause of death (more than 7 million deaths annually) and imposing an enormous global economic burden. In the US alone, there are 17.6 million CHD patients, and the estimated annual incidence of new and recurrent myocardial infarction is estimated to be 935,000. The ensuing direct and indirect costs in the US are estimated at $177 billion in 2010. Accurate early diagnosis of CHD plays a crucial role in improving the prognosis of patients and in reducing the long-term costs of medical treatment. The current first line diagnostic test, standard stress ECG, lacks the desired accuracy and often leads to further testing. HFQRS is thus significant for insurance companies because it can potentially save thousands of dollars per patient by reducing the performance of costly imaging procedures which unnecessarily expose the patient to radiation. Patients are often also referred even to invasive coronary angiography as a result of false positive stress ECG and imaging tests.

Links

 * Biological Signal Processing Manufacturer of HyperQ Systems