Evaluation of depolarization changes during acute myocardial ischemia by analysis of QRS slopes.

Department of Cardiology, Lund University, Lund, Sweden.
Journal of electrocardiology (Impact Factor: 1.08). 04/2011; 44(4):416-24. DOI: 10.1016/j.jelectrocard.2011.03.005
Source: PubMed

ABSTRACT This study evaluates depolarization changes in acute myocardial ischemia by analysis of QRS slopes.
In 38 patients undergoing elective percutaneous coronary intervention, changes in upward slope between Q and R waves and downward slope between R and S waves (DS) were analyzed. In leads V1 to V3, upward slope of the S wave was additionally analyzed. Ischemia was quantified by myocardial scintigraphy. Also, conventional QRS and ST measures were determined.
QRS slope changes correlated significantly with ischemia (for DS: r = 0.71, P < .0001 for extent, and r = 0.73, P < .0001 for severity). Best corresponding correlation for conventional electrocardiogram parameters was the sum of R-wave amplitude change (r = 0.63, P < .0001; r = 0.60, P < .0001) and the sum of ST-segment elevation (r = 0.67, P < .0001; r = 0.73, P < .0001). Prediction of extent and severity of ischemia increased by 12.2% and 7.1% by adding DS to ST.
The downward slope between R and S waves correlates with ischemia and could have potential value in risk stratification in acute ischemia in addition to ST-T analysis.

  • International Journal of Bioelectromagnetism. 12/2013; 15(1):77-82.
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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.
    Journal of Electrocardiology. 07/2014; 47(4):512-519.
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    ABSTRACT: OBJECTIVE: In acute myocardial ischemia changes within the QRS complex can add valuable information to that from the repolarization phase. This study evaluates three angles obtained from the main slopes of the R-wave within the QRS complex to assess acute myocardial ischemia. METHODS: The QRS angles, denoted by ØR (R-wave angle), ØU (up-stroke angle) and ØD (down-stroke angle), were evaluated in 12-lead electrocardiogram (ECG) recordings of 79 patients before and during coronary occlusion by elective percutaneous coronary intervention (PCI). In a subset of 38 patients, ischemia was quantified by myocardial scintigraphy. RESULTS: At baseline the QRS angles presented low variations. During occlusion, ØU and ØD developed a fast and abrupt change, whereas ØR showed a smaller and gradual change. There were significant correlations between both maximal and sum of positive change in ØR and ischemia: r=0.67; p<0.001 and r=0.78; p<0.001, for extent, and r=0.60; p<0.001 and r=0.73; p<0.001, for severity, respectively. Prediction of extent and severity of ischemia increased by 50% by adding ØR changes to ST-segment changes, for LCX occlusions, whereas increased by 12.1% and 24.6% for LAD and RCA occlusions, respectively. No significant correlation was seen between ØU and ØD angles and ischemia. CONCLUSIONS: Evaluation of QRS angles from the standard 12-lead ECG represents a sensitive marker for detection of acute myocardial ischemia, whereas, ØR changes can be used for prediction of its extent and severity.
    Journal of electrocardiology 03/2013; · 1.08 Impact Factor

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