Noninvasive detection of repolarization changes in the heart
Eva Heblakova1, Milan Tysler, Marie Turzova
1Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia. umerhebl@savba.sk
Insights
This study tested an inverse method for detecting myocardial repolarization changes using QRST integral maps. The method showed potential but was less effective in some patients with effort angina pectoris.
Area of Science:
- Cardiology
- Biophysics
Background:
- Previous studies utilized an inverse method based on dipolar representation of QRST integral map differences to identify localized repolarization changes.
- This method proved effective in patients with coronary artery disease post-revascularization.
Purpose of the Study:
- To validate the inverse method for detecting myocardial repolarization changes.
- To assess the method's efficacy in healthy individuals and patients with effort angina pectoris.
Main Methods:
- Analyzed changes in QRST integral maps following sublingual nitroglycerin administration.
- Computed the single dipole that best represents the difference QRST integral map using an inverse method.
Main Results:
- Significant QRST integral map changes (>15%) were observed in 4 individuals after nitroglycerin, post heart rate compensation.
- Dipolar approximation of difference integral maps had a low root mean square error (<35%) in only 2 subjects; errors exceeded 50% in others.
Conclusions:
- The nitroglycerin test may reveal minor repolarization changes detectable by the inverse method.
- The test did not consistently induce detectable repolarization changes in all patients with effort angina pectoris.
Objective:
Previously reported inverse method based on dipolar representation of differences in QRST integral maps with and without manifestation of local repolarization changes has shown the ability to identify small areas in the myocardium responsible for these changes in a group of patients with coronary artery diseases underwent revascularization. The aim of this study was to verify this approach on a group of 4 healthy persons and a group of 7 patients suffering from effort angina pectoris.
Methods:
Changes in QRST integral maps after nitroglycerine sublingual application were examined and single dipole best representing the difference QRST integral map was inversely computed.
Results:
After attempted compensation of heart rate variations, changes in QRST integral maps greater than expected intra - individual variability (over 15%) were detected in 4 persons. Obtained difference integral maps could be sufficiently approximated by maps generated by single current dipole only in 2 persons with relative root mean square (rms) error less than 35%; in the rest of subjects relative rms error of the dipolar map approximation was greater than 50%.
Conclusion:
Results suggest that small repolarization changes might be detectable after nitroglycerine test, however this test did not induce detectable changes in some patients with effort angina pectoris.
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