ECG – anterior ST depression: Findings and interpretation
PR interval is grossly prolonged – 400 ms. Notched r seen in V2, possibly an incomplete right bundle branch block. AVL shows QS complex. Tall R waves in V4- V6. Gross ST segment depression with T inversion is seen throughout anterior and lateral chest leads, indicating significant myocardial injury, most likely due to Non ST Elevation Myocardial Infarction (NSTEMI). PR interval prolongation would indicate involvement of the AV node by the ischemic process. As there is no feature to suggest inferior wall infarction, AV conduction disturbance with anterolateral ischemic changes would indicate a dominant left circumflex coronary artery involvement. Presence of extensive anterior changes is not typical of isolated circumflex disease. Hence we may have to consider associated left anterior descending (LAD) coronary artery disease or left main coronary artery disease. But no ST segment elevation is visible in aVR to suggest left main coronary artery disease. A type III LAD which ‘wraps around’ the apex and supplies the inferior wall is another reason for inferior wall infarction with LAD occlusion. But a ‘wrap around’ LAD is unlikely to go up and supply the AV node as well.
The third beat in the sequence has no definite P wave and could be a junctional ectopic beat. But a good multi lead rhythm strip is needed to delineate the exact mechanism
(Please post any different explanation as a comment below – and don’t forget to read the comments which contain good discussions!).
Printed data at the bottom of the tracing indicate the settings of the ECG machine during the recording: Auto – means that all leads will be recorded automatically once the record button is pressed after connecting the leads. 25 mm/s indicates the speed at which the paper will move during the recording (X-axis of the graph). 10 mm/mV indicates the standardization (Y-axis of the graph). This is also illustrated by the rectangular standardization pulse at the beginning of the graph. 50 Hz indicates the notch filter for removing interference from line voltage alternating current. 0.08-35 Hz gives the limits of the high pass and low pass filters. The ECG amplifier receives only signals in this frequency range. High pass filter filters respiratory fluctuations and low pass filter removes artifacts due to muscle activity. 77 BPM is the average heart rate measured by the analysis program from the RR interval.