Simply a Sinus STEMI? No!

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Paramedics respond to a 55 yo female with chest pain and shortness of breath. The patient is alert and hypertensive. The peripheral pulse is irregular.

12 lead ECG: 

12 Lead ECG Interpretation:

The underlying rhythm is most definitely not sinus. A rhythm strip is not included in the LifeNet transmission. Though the first visualized QRS complex in leads I, II, and III APPEARS to be conducted, there is PR interval is excessively long (> 0.2seconds). Furthermore, the P to P intervals appear constant. There is a "p" hiding in the ST segment of the next QRS complex. The constant P to P interval suggests a third degree heart block. ST segment elevation is present in the inferior leads. Reciprocal change is evident in the anterior-septal (V1-V6) and lateral (I, aVL) leads. Recall that ST depression in the septal leads (V1-V2) could indicate posterior involvement. Posterior wall changes generally exhibit tall R waves in leads V1-V3 which are absent in this particular tracing. 

Third degree heart block, inferior wall ST segment myocardial infarction with possible posterior extension. 

12 lead ECG Case Discussion:

This case highlights the importance of a rhythm strip. If there is any question about the presence or absence of an underlying conduction problem, always obtain a rhythm strip. LifeNet provides just a few seconds of rhythm analysis; this interval is occasionally inadequate for proper rhythm determination. Inferior wall changes, coupled with the heart block, suggest injury to the SA node. This patient would benefit from the prophylactic application of pacing pads. Avoid nitrogylcerin in the presence of inferior wall changes and an underlying heart block. 

The "buried P wave" and constant P to P interval: 

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Anterior Wall Changes and Abnormal ECG, UNCONFIRMED!

A 60 yo male with a history of CAD, MI, and HTN presents with retrosternal chest discomfort. He is hemodynamically stable. The prehospital provider obtains a 12 lead ECG.

12 lead ECG interpretation: 

A sinus tachycardia is present, and there are plenty of abnormal ST segment changes to point out. First, there is minimal ST segment elevation in V1, V2, and V3 .The ST approaches 2 mm in V2. In addition, the ST segments have a non-concave, or worrisome, appearance in V4. There is T wave inversion in aVL and downsloping ST segments in lead I. Those ST segments resemble the pattern of "ventricular strain."

Sinus tachycardia, ST segment elevation in the anterior precordial leads, anterior and lateral T wave inversion consistent with ischemia.

12 lead ECG case discussion: 

The paramedic scrutinized the anterior ECG changes and declared a, "STEMI." Though the receiving facility determined that the initial prehospital ECG changes did not meet strict STEMI criteria, the paramedic was clearly advocating for the patient's best interest by electing to transport directly to a cardiac interventional center. Previous ECGs from the same patient reflected prior ST segment abnormalities, and the patient wasd admitted to the cardiology service for further testing. Minor, baseline ST segment elevations in precordial leads in addition to high left ventricular voltage can confound the diagnosis of STEMI. The presence of at least 2 mm of elevation plus the identification of reciprocal change (in the form of ST segment depression) makes the diagnosis of STEMI much more likely. Always remember that serial ECGs are extremely important when dealing with concerning or "borderline" presentations.