Conference Paper

A vectorial approach for evaluation of depolarization changes during acute myocardial ischemia

Commun. Technol. Group, Univ. of Zaragoza, Zaragoza, Spain
Conference: Computing in Cardiology, 2010
Source: IEEE Xplore


In the present study we evaluated the upslope (IUS), downslope (IDS) and terminal slope (ITS) of the QRS complex in both standard and derived ECG leads obtained from spatial QRS loops, either by the vectorcardiogram (VCG) or by principal component analysis (PCA), in 79 patients undergoing prolonged, elective percutaneous coronary intervention (PCI). For each patient, the slope indices IUS, IDS and ITS were evaluated in the PCI recording as well as in a control recording acquired before the PCI procedure, and relative factors of change during PCI were calculated. We showed that IUS and IDS computed over VCG and PCA leads present higher sensitivity to the ischemia-induced changes than the same indices evaluated over the standard 12-lead ECG. Mean relative factors of change were 10.5 and 12.4 for IUS and IDS in PCA, and 7.87 and 13.7, respectively, in VCG, representing an increase in sensitivity of up to 103% for IUS and 46% for IDS compared to measurements obtained in lead V3. We conclude that evaluation of slope indices in leads derived from QRS loops significantly increases their potential value for detection of acute myocardial ischemia.

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    ABSTRACT: Introduction Low-level electrocardiographic changes from depolarization wavefront may accompany acute myocardial ischemia. The purpose of this study was to assess the changes of microvolt amplitude intra-QRS potentials induced by elective percutaneous coronary interventions (PCI). Methods Fifty-seven patients with balloon inflation periods ranging from 3.1 to 7.3 minutes (4.9 ± 0.7 min) were studied. Nine leads continuous high-resolution ECG before and during PCI were recorded and signal-averaged. Abnormal intra-QRS at microvolt level (μAIQP) were obtained using a signal modeling approach. μAIQP, R-wave amplitude and QRS duration were measured in the processed ECG during baseline and PCI episodes. Results The mean μAIQP amplitude significantly decreased for each of the standard 12 leads at the PCI event respect to baseline. Left anterior descending artery (LAD) occlusion resulted in a decrease μAIQP in both the precordial leads and the limb leads, while right coronary (RCA) and left circumflex (LCx) arteries occlusions mainly affected limb leads. R-wave amplitude increased during PCI in RCA and LCx groups in lead III but decreased in the precordial leads, while the amplitude decreased in the LAD group in lead III. The average duration of the QRS augmented in groups RCA and LCx but not in the LAD group. Conclusions Abnormal intra-QRS potentials at the level of μV provide an excellent tool to characterize the very-low amplitude fragmentation of the QRS complex and its changes due to ischemic injuries. μAIQP shows promise as a new ECG index to measure electrophysiologic changes associated with acute myocardial ischemia.
    Full-text · Article · Jul 2014 · Journal of Electrocardiology