Non Sustained VT: Making a Lasting Impression!

Putting on the Pressure

A 60 yo male presents to EMS with several hours of chest pressure and diaphoresis. A 12 lead ECG is obtained following a 10 beat run of non sustained ventricular tachycardia. Despite the EMT's excitement at "firing up the paddles," the paramedic administers 324 mg of aspirin and prepares for transport to the nearest facility capable of percutaneous coronary intervention. Your partner informs you that the monitor discerns the presence of a paced rhythm. The patient has no previous medical history.


12 LEAD ECG:

12 LEAD ECG Analysis:

A sinus rhythm is present and the rate is regular. Diffuse and concerning ST segment changes appear in this tracing. First, pathologic ST segment elevation occurs in leads V2, V3 and V4. Q waves also appear throughout the tracing. The monitor misinterprets the ischemic Q wave as a pacer spike. The QRS is narrow, so an interventricular conduction delay is less likely responsible for the "false pacer" call. Reciprocal changes appear in lead aVF. There is minimal J point depression in lead III and V6. The baseline is also irregular.


12 Lead ECG Interpretation: 

Sinus rhythm, anterior wall ST segment myocardial infarction.

Comments:

• It is difficult to discern the location of the anatomic lesion based upon this ECG. The large ST segment elevation in the precordial leads suggests involvement of the LAD. The findings of lateral wall ischemia could implicate the circumflex as well. 
• The run of VT was likely due to ventricular irritability. Remember that the most devastating complications of anterior wall ischemia are lethal dysrhythmia and cardiogenuc pulmonary edema 
• Pathologic Q waves generally follow a few rules: (1) larger than a third of the corresponding R wave or (2) measure in excess of 0.03 seconds. Q waves that accompany poor R wave progression are more likely to indicate ischemia. 

The Subtlety of STE and its Anatomy

This tracing was discussed at a recent STEMI committee meeting. Its much easier to spot the ischemic changes once the diagnosis is known.....

Subtle STE or artifactual nonsense ?

12 LEAD ECG INTERPRETATION

Baseline sinus rhythm, occasional fusion beats and premature atrial contractions in a bigeminal pattern, ST segment elevation in septal leads

This ECG interpretation is far from obvious. Typical criteria for activation of the cardiac catheterization lab includes at least 2 mm or greater of STE in contiguous precordial leads. Close inspection reveals minimal ST elevation in leads V2 and V3. Clear cut reciprocal changes are not present. The ST segment's shape is far from reassuring: it has a horizonal and ischemic-type appearance in lead V2.

This ECG requires you to bust out the calipers because there is a constant PR interval buried within the premature and fusion beats. At first glance, the irregular rhythm suggests atrial fibrillation. The presence of consistent PR intervals, however, rules out that diagnosis. On most tracings, P waves are best visualized in leads II and V1.

The patient went to the cardiac cath lab; the diagnosis of an acute occlusion of the "ramus." The ramus is simply an intermediate branch of the left coronary artery (LCA)  that arises in between the left anterior descending (LAD) artery and the left circumflex coronary artery. The "ramus" is abbreviated as "Int" in the illustration below.


For those of use who are more visual learners, this picture is furnished courtesy of:
http://www.cardiologysite.com/html/lad.html