ST Segment on ECG: Significance and Interpretation

Introduction

The ST segment is an important segment on the ECG tracing, located between the QRS complex and the T wave. Understanding its characteristics and interpretation is crucial for identifying cardiac events.

ST Segment and its Baseline

The ST segment should ideally be isoelectric:

• Baseline Appearance: The ST segment should appear as a flatline at the same level as the baseline.

ST Elevation

ST elevation can indicate a cardiac event:

• ST Elevation MI (STEMI): ST elevation can be a sign of myocardial infarction (heart attack).
• Measurement Criteria: ST elevation is measured as elevation above two small squares on the ECG.
• Response: If significant ST elevation is observed, contact the cardiac unit for primary percutaneous coronary intervention (PPCI).

ST Depression

ST depression may also have diagnostic implications:

• Measurement Criteria: ST depression is measured as depression of more than two small squares on the ECG.
• Response: If significant ST depression is observed, contact the nearest PCI center promptly.

Interpretation and Patient Considerations

Interpretation and patient considerations for ST elevation and depression:

• Consider Patient History and Symptoms: Not all cardiac events show ST elevation or depression, so rely on patient history and presenting symptoms.
• Special Cases: Patients with conditions like diabetes may not exhibit typical symptoms or ECG changes.
• Lead Correlation: Note the leads showing ST elevation or depression as it can indicate specific areas of the heart affected, such as a septal myocardial infarction.
• Communication: Share the specific lead findings with PCI centers or other healthcare providers involved in the patient's care.

Conclusion

The ST segment on an ECG carries important diagnostic information. Understanding ST elevation, ST depression, and their correlation to specific leads and cardiac conditions helps guide appropriate interventions and patient management.