ST changes and temporal relation to the J point during heart rate increase and myocardial ischemia
Michael F Haney1, Sören Häggmark, Göran Johansson
1Anesthesiology and Intensive Care Medicine, University Hospital, Umeå, Sweden. michael.haney@anestesi.umu.se
Insights
Measuring ST segments during ischemia is consistent across different J-point intervals. This finding simplifies ST analysis in electrocardiogram (ECG) interpretation for patients with coronary artery disease experiencing tachycardia.
Area of Science:
- Cardiology
- Medical Technology
Background:
- The precise J-point interval for ST segment measurement in electrocardiogram (ECG) analysis remains debated.
- Accurate ST segment assessment is crucial for diagnosing ischemia, especially during increased heart rate (tachycardia).
Purpose of the Study:
- To investigate the relationship between different J-point intervals and ST segment changes during induced tachycardia and ischemia.
- To determine if ST vector magnitude (STC-VM) and summed ECG ST changes are affected by J-point measurement timing.
Main Methods:
- 34 symptomatic patients with coronary artery disease underwent incremental pacing to induce ischemia.
- ST vector magnitude and ST changes were measured at J+0, J+20, J+60, and J+80 milliseconds.
- Measurements included ST vector change from baseline (STC-VM) and the sum of ST changes across all 12 ECG leads (ECG ST sum).
Main Results:
- ST segments showed similar increases during pacing-induced tachycardia and ischemia.
- No significant differences in STC-VM or ECG ST sum were observed across the tested J-point intervals.
- ST segment analysis using ST change from baseline proved consistent regardless of J-point measurement timing.
Conclusions:
- ST segment assessment in pacing-induced ischemia is not significantly influenced by the choice of J-point interval (0-80 ms).
- This suggests flexibility in ST measurement timing for vectorcardiographic ST analysis during tachycardia and ischemia.
Abstract:
There is no concensus concerning where in the ST segment to measure. We studied the relation between different J point intervals to ST results during tachycardia and ischemia. Symptomatic (anesthetized) patients with coronary artery disease were paced at ascending incremental levels until they became ischemic. ST vector magnitude and ST vector change from baseline (STC-VM) as well as the sum of ST changes from all 12 electrocardiogram (ECG) leads (ECG ST sum) were measured at J point 0 millisecond, J + 20, J + 60, and J + 80 milliseconds for 34 patients. ST segments increased in similar fashion during pacing and ischemia. There was no difference in ST results when measurement was performed at different time intervals for both STC-VM and ECG ST sum. We conclude that ST assessment by ST change from baseline is not affected by different J point intervals during increased heart rate and ischemia in this clinical model of pacing-induced ischemia and vectorcardiographic ST analysis.
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