Hilton Head Island Fire & Rescue 12-lead ECG Case of the Month September 2009 STEMI Program

EMS is dispatched to a 62 year old male with a chief complaint of chest discomfort. On arrival, the patient is found sitting at the dinner table. He appears acutely ill. Onset : Fairly sudden after sitting down for dinner 20-30 minutes ago Provoke : Nothing makes the pain feel better or worse Quality : Dull pressure/ache Radiation : The pain does not radiate Severity : 8/10 "feels like a 747 is sitting on his chest" Time : Feels slightly better since the onset Skin: cool, pale, diaphoretic Vital signs: Resp: 20 Pulse: 62 BP: 84/48 SpO2: 99 on RA Breath sounds: clear

The cardiac monitor is attached at 17:54:24. Note the filter is set to “monitor mode” at 1 – 30 Hz.

Using the “large block method” the heart rate can be estimated at 60/min The rhythm is sinus with P waves and QRS complexes in a 1:1 relationship.

12-Lead 1 is captured at 17:55:42 The filter selection is now set to “diagnostic mode” at 0.05 – 40 Hz. The low frequency filter must be set to 0.05 Hz to obtain accurate readings of the ST-segment.

The data quality is good except for lead V6 which is showing loose electrode artifact.

12-Lead 2 is captured at 17:56:38 The data quality is now excellent but for some reason the “Data quality prohibits interpretation” message persists.

12-Lead 3 is captured at 17:58:26 The GE-Marquette 12SL interpretive algorithm is now giving the ***ACUTE MI SUSPECTED*** message.

Excellent job trouble shooting the monitor and obtaining a high quality ECG tracing! The importance of this to the success of our STEMI program cannot be overstated !

Critical question! Do we agree with the computer’s assessment?

ST-segment elevation present?

ST-segment elevation > 1 mm is present in lead II, III and aVF. Yes!

Are leads II, III and aVF contiguous?

Yes! V6 Lateral V3 Anterior aVF Inferior III Inferior V5 Lateral V2 Septal aVL Lateral II Inferior V4 Anterior V1 Septal aVR I Lateral

Are reciprocal changes present?

I, aVL II, III, aVF INFERIOR V1, V2, V3, V4 NONE POSTERIOR II, III, aVF I, aVL, V3, V4, V5, V6 ANTEROLATERAL II, III, aVF I, aVL, V5, V6 LATERAL NONE V1, V2, V3, V4 ANTEROSEPTAL NONE V3, V4 ANTERIOR NONE V1, V2 SEPTAL RECIPROCAL FACING SITE

Reciprocal ST-segment depression is present in leads I and aVL. It’s hard to miss the downsloping ST-segment in lead aVL. The flattening of the ST-segment in lead I is a more subtle finding. Yes!

I, aVL II, III, aVF INFERIOR V1, V2, V3, V4 NONE POSTERIOR II, III, aVF I, aVL, V3, V4, V5, V6 ANTEROLATERAL II, III, aVF I, aVL, V5, V6 LATERAL NONE V1, V2, V3, V4 ANTEROSEPTAL NONE V3, V4 ANTERIOR NONE V1, V2 SEPTAL RECIPROCAL FACING SITE

Reciprocal ST-segment depression is also present in the right precordial leads (suggesting posterior involvement). Yes!

STEMI Alert criteria met?

Patient has signs and symptoms of ACS 12 lead ECG shows excellent data quality Computer reads ***ACUTE MI SUSPECTED*** Paramedic agrees with computer interpretation QRS duration is < 120 ms (0.12 s) ECG shows 1 mm of ST-segment elevation in 2 or more contiguous leads (2 mm in leads V2 or V3) Reciprocal changes are present Contact dispatch and announce “STEMI Alert” Transmit the ECG to the emergency department

Yes! and Yes! At this point the EMS crew has all the information they need to contact dispatch and announce “STEMI Alert!” The ECG should be transmitted to the hospital immediately.

When you call in, the only information you are required to give is the following: Your name and medic unit call sign The fact that it is a STEMI Alert The first and last name of the patient The patient’s date of birth The age, gender and chief complaint The vital signs Whether or not the patient has a preferred cardiologist It is assumed that STEMI patients will be treated according to protocol.

When you call in, the only information you are required to give is the following:

Your name and medic unit call sign

The fact that it is a STEMI Alert

The first and last name of the patient

The patient’s date of birth

The age, gender and chief complaint

The vital signs

Whether or not the patient has a preferred cardiologist

It is assumed that STEMI patients will be treated according to protocol.

Clinical pearl

EMS is dispatched to a 62 year old male with a chief complaint of chest discomfort. On arrival, the patient is found sitting at the dinner table. He appears acutely ill. Onset : Fairly sudden after sitting down for dinner 20-30 minutes ago Provoke : Nothing makes the pain feel better or worse Quality : Dull pressure/ache Radiation : The pain does not radiate Severity : 8/10 &quot;feels like a 747 is sitting on his chest&quot; Time : Feels slightly better since the onset Skin: cool, pale, diaphoretic Vital signs: Resp: 20 Pulse: 62 BP: 84/48 SpO2: 99 on RA Breath sounds: clear Remember the presentation? Whenever you have a patient with acute inferior STEMI you should consider the possibility of right ventricular infarction! This is especially true when the patient presents with borderline bradycardia and hypotension!

The easiest and safest thing to do is presume that right ventricular infarction is also present and treat the patient accordingly! This means that patients with a marginal blood pressure should not receive nitroglycerin or morphine! Obtain IV access and give the patient a fluid bolus before you even consider drugs that could bottom out the patient’s blood pressure! You can also consider modified precordial leads V4R and V5R, which is exactly what the paramedics on this call decided to do.

V1 V2 V3 V4R V6 V5R

V4R V5R V4R V5R Is ST-segment elevation present in modified chest leads V4R and V5R?

V4R V5R V4R V5R Surprisingly…. No!

Why?

Because the culprit artery was not the right coronary artery (RCA) as we might have expected with acute inferior STEMI. Here we see the angiogram showing a 100% occlusion of the circumflex artery (LCX) which branches off the left coronary artery.

Before After

Once blood flow is restored, you can see how the LCX branches off into a manifold that supplies the inferior wall of the left ventricle.