Where is the Circulatory Road Block?

Case

An 81 y/o female with DM, HTN, and bilateral lower extremity amputations presents to EMS with chest pain and vomiting. VS: BP: 90/40, P: 80, R:16. Sp02: 95%. The patient is alert and oriented and in mild distress. An ECG is obtained. What is your interpretation ?

12 Lead ECG

ECG Interpretation 

A first degree AV block is present. Deep Q waves and ST elevations are present in the inferior leads III, and aVF. Additional ST segment elevations are present in the anterior precordial leads V3, V4, and V5. Reciprocal depression is present in leads I and aVL. A right bundle branch block is suggested by the positively deflected QRS and increased QRS duration seen in V1. This patient is experiencing a large STEMI given the presence of elevation in multiple territories. ST elevations suggest active injury and ischemia in the inferior and anterior leads. The relative hypotension may indciate cardiogenic shock. Cardiogenic shock complicates a significant percentage of anterior wall myocardial infarctions. Multi-territorial ST elevations indicates a poor prognosis.

Treatment Course 

Providers transmit the 12 lead ECG and alert the receiving facility of an ST elevation myocardial infarction. Aspirin is administered. The patient proceeds directly to the cath lab. The patient had severe, multi-vessel, obstructive coronary artery disease and unfortunately expired from decompensated cardiogenic shock

Key Points

• Remain vigilant for the presence of cardiogenic shock in the presence of anterior wall ischemia
• ST elevations in multiple geographic areas (inferior and anterior in this case) indicate severe disease
• Ventricular fibrillation can also accompany large anterior wall MIs
• Relative hypotension is extremely significant in patients who are accustomed to higher blood pressures. In this case, the patient's marginal blood pressure resulted from acutely decreased cardiac output. 

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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"Abnormal ECG" and Bypass of the Closest Facility

So.. would you call this one and activate the cath lab from the prehospital ECG? The patient is a 72 year old female with severe uncontrolled hypertension. She called 911 for mild shortness of breath. Her blood pressure is over 200 mm Hg systolic. The patient is awake, alert, and oriented. The paramedic is bypassing a local facility in favor of the closest cardiac interventional center.

What's your analysis?

12 Lead ECG

 

12 Lead ECG Interpretation and Discussion

A baseline sinus rhythm is present. There is a significant amount of artifact that interferes with interpretation in the limb leads. A fusion beat is seen in the limb lead tracings. However, there is > 1mm of ST segment elevation in lead III. Lead aVF also has minimal ST segment elevation. Pathologic Q waves are present in contiguous leads (III and aVF). Though an isolated Q wave is common in limb lead III, the presence of Q waves in contiguous inferior leads (III and aVF) suggests ischemia. In addition, ST segment depression is present in the reciprocal leads of I and aVL. This finding further supports the presence of acute injury. ST segment elevations are also seen in leads aVR and V1. As discussed in a previous case, the presence of STE in leads aVR and V1 may predict obstruction of the left main coronary artery. Poor R wave progression is present across the precordial leads V2-V6. This finding  (the loss of R wave amplitude) is consistent with the machine generated diagnosis of "anterior infarct, age undetermined." These findings, when put together, reveal an inferior wall STEMI. This patient is best cared for at a facility capable of percutaneous cardiac intervention.

Final interpretation

Sinus rhythm, inferior wall STEMI. Anterior wall ischemia. Reciprocal changes in the form of ST depression present in the anterior-lateral limb leads.

All that elevates isn't STEMI

Further confounding the already difficult job done by EMTs and paramedics is the idea of falsely positive ST segment elevation. Even when the EMS provider's eyes are focused on the STE prize, there are lots of distractors out there. This ECG was transmitted as a "priority one" STEMI patient. The cath lab was NOT activated from the field.

Of course, providers should ALWAYS err on the side of caution and transport patients with concerning ECG findings to the closest appropriate hospital. That said, this ECG is a bit more reassuring when placed under a bit more intensive scrutiny.

The patient as an otherwise healthy 30 year old male. The patient had no previous medical history and reported constant chest discomfort over the past week. The patient denies nausea, vomiting, shortness of breath, syncope, or other associated symptoms.  Vitals were unremarkable except for a blood pressure of 140/76. The patient appeared non toxic and in no acute distress.

12 lead ECG:

12 Lead ECG and Discussion

There is a baseline sinus bradycardia. Tall R waves are present in the limb leads and in the precordial leads V4 and V5. These tall R waves are most appropriately called, "high left ventricular voltage." Left ventricular hypertrophy is not technically correct since this patient is (1) young and (2) we don't have a formal echocardiogram. High left ventricular voltage may be a physiologic finding in young and otherwise healthy patients. Slight ST segment elevation is present in leads V2 and V3. There is J point elevation in lead II as well. Slight ST segment elevation may also be a physiologic finding- in the ABSENCE of a concerning patient presentation. This particular patient had no concerning medical history and appeared well. Also reassuring is the ABSENCE of reciprocal change.

The shape of the ST segment can also help guide your medical decision making. Pathologic ST segments are typically more horizontal in shape. Convex ST segments are also associated with worsent outcomes. Test for convexity by drawing a line from the J point to the peak of the T wave. If the line superimposes the ST segment or if the T wave appears above the drawn line, the ST segment is classified as convex. Convex shape= NOT reassuring. Broad based and wide ST segments also favor ischemia.

Here is an "ugly" appearing ST segment. No offence intended to the poor ST segment depicted:

Another NOT reassuring ST segment :