Prehospital 12 lead ECG quiz for the kitchen table

1. Which of the following statements about axis determination is false?

a.) The normal quadrant is the left inferior quadrant.
b.) When leads I and aVF show an upright QRS complex, the axis is in the normal quadrant.
c.) For the axis to be normal, the QRS complex in lead I can be negative as long as the QRS complex in leads II and III are positive.
d.) If the QRS complex in lead aVL is equiphasic, it means the heart’s mean electrical vector is moving perpendicular to that lead.

2. You attach the limb leads and the monitor shows artifact in leads I and III. You should:

a.) Trouble shoot the white electrode.
b.) Trouble shoot the black electrode.
c.) Trouble shoot the red electrode.
d.) Trouble shoot the green electrode.

3. Your patient is a 68 year old male complaining of chest pain. You capture a 12 lead ECG which shows ST segment elevation in leads III and aVF and ST segment depression in lead aVL. What is the most likely cause?

a.) Pericarditis
b.) Acute anterior ST elevation myocardial infarction
c.) Acute inferior ST elevation myocardial infarction
d.) Benign early repolarization

4. True or false. Acute myocardial infarction is the most common cause of ST segment elevation in chest pain patients.

a.) True
b.) False

5. You are treating a patient with shortness of breath. You capture a 12 lead ECG which shows sinus rhythm, a QRS duration of 148 ms, an rS complex in lead V1, and a monophasic R wave in lead I. The T waves are discordant with the QRS complex throughout the ECG. The most likely explanation is:

a.) Left ventricular hypertrophy
b.) Left bundle branch block
c.) Nonspecific intraventricular conduction defect
d.) Right ventricular hypertrophy with strain pattern

6. Which of the following statements about acute inferior ST elevation myocardial infarction is false?

a.) Patients with inferior ST elevation myocardial infarction are candidates for immediate reperfusion therapy.
b.) Patients with inferior ST elevation myocardial infarction tend to have a better prognosis than patients with anterior ST elevation myocardial infarction.
c.) Patients with inferior ST elevation myocardial infarction may also be experiencing right ventricular infarction.
d.) The most common arrhythmia associated with inferior myocardial infarction is sinus tachycardia.

7. You are treating a 35 year old male complaining of anxiety and palpitations. He states that he has a history of arrhythmias. The monitor is attached and shows a slightly irregular wide complex tachycardia at a rate of 258. A 12 lead ECG is captured. The computerized interpretive statement reads:

ABNORMAL ECG **UNCONFIRMED**
• Supraventricular tachycardia
• Right bundle branch block, plus right ventricular enlargement
• Lateral infarct, age undetermined
• T wave abnormality – consider inferior ischemia

The patient is hemodynamically stable and an IV has been established. You should:

a.) Suspect the possibility of an accessory pathway and provide supportive care only. Provide synchronized cardioversion if the patient becomes unstable.
b.) Give 150 mg Amiodarone mixed in a 50 ml bag of 0.9 NS over 10 minutes.
c.) Perform vagal maneuvers. If unsuccessful, give Adenocard, rapid IV push followed with a flush.
d.) Prepare the patient for immediate synchronized cardioversion.

8. You are called to the home of a 88 year old male with a complex medical history including heart failure and renal insufficiency. The chief complaint is general weakness, mild dyspnea, and vomiting. Medications include a beta blocker, an ACE inhibitor, a diuretic, and potassium supplements. A 12 lead ECG is attached and shows an undetermined rhythm with wide QRS complexes at a rate of 80. You suspect:

a.) Hyperkalemia
b.) Hypokalemia
c.) Acute pulmonary edema
d.) Acute myocardial infarction

9. Which of the following statements about reciprocal changes is false?

a.) Reciprocal changes are strong supportive evidence that ST segment elevation represents acute myocardial infarction.
b.) Leads I and aVL are reciprocal to each other.
c.) Leads I and II are reciprocal to each other.
d.) Leads III and aVL are reciprocal to each other.

10. Which of the following statements about prehospital 12 lead ECGs is false?

a.) For patients with suspected ACS, a prehospital 12 lead ECG should be captured with the first set of vital signs.
b.) If you are close to the hospital, it is more important to give nitroglycerin than capture a prehospital 12 lead ECG.
c.) You should perform serial prehospital 12 lead ECGs to record dynamic changes in supply vs. demand characteristics that might indicate an acute coronary syndrome.
d.) Poor data quality can lead to incorrect computerized interpretive statements on the 12 lead ECG.


Answers:
1.) C
2.) B
3.) C
4.) B
5.) B
6.) D
7.) A
8.) A
9.) B
10.) B

66 yom CC: Chest pain

Here's an interesting case that illustrates the value of the prehospital 12 lead ECG.

A 66 year old male became suddenly ill while playing tennis. Bystanders state that he struck the ball with his racket, staggered a few steps, placed his hand over his chest, and sat down on the tennis court.

9-1-1 was contacted immediately.

Past medical history is significant for hypertension, hyperlipidemia, and a "previous episode of chest pain" for which the patient carries SL NTG which he rarely takes PRN for chest discomfort.

A paramedic from out-of-town was present on scene and gave the patient his own NTG.

On EMS arrival, the patient appears acutely ill. He is diaphoretic and weak, complaining of chest pain.

Vital signs are assessed.

Pulse: 72
Resp: 20
BP: 88/58
SpO2: 98 on RA

The cardiac monitor is attached.


Even in monitor mode, you can see ugly looking ST segment elevation in lead III with reciprocal ST segment depression in lead I.

A 12 lead ECG is captured.


This removes all doubt. The ECG shows acute inferior STEMI. There are Q waves in leads III and aVF with ST segment elevation. There are downsloping ST segments in leads I and aVL which represent reciprocal changes.

The 12 lead ECG was transmitted to the local receiving PCI hospital.

The paramedic in charge of the call (good job Tina H.) placed the patient on oxygen, had the patient chew up 4 baby aspirin, started an IV, gave the patient a fluid bolus, and administered SL NTG and 5 mg of morphine.

Look at the next 12 lead ECG captured less than 10 minutes later.


Where is the ST segment elevation? It's gone. The ECG is now non-diagnositc.

If not for the prehospital 12 lead ECG, there's no telling how long this patient would have sat in the emergency department, infarcting away.

Instead, the patient had a 39 minute door-to-balloon (D2B) time.

If you know any old-school paramedics, medical directors, or administrators who care about patients but still aren't sure prehospital 12 lead ECGs are necessary, be sure to share this case with them!

AHA ML survey reveals problems

See news release:

American Heart Association EMS Survey Uncovers Deficiencies in Response, Treatment and Transfer of Patients With Most Deadly Heart Attacks

The American Heart Association's Mission: Lifeline (AHA ML) conducted a survey of the nation's EMS systems.

Significant findings include:

• Only half of EMS systems have 12 lead ECG monitors on 75 percent or more of their vehicles.
• Of EMS systems with 12 lead ECGs, most lacked a standard method for EMS to communicate the results to the hospital. Currently, paramedics use one or more of the following methods: 1.) verbally reporting the computerized interpretation, 2.) verbally reporting their own interpretation of the ECG reading, or 3.) using an advanced technology like Bluetooth or mobile phone to transmit the ECG for physician interpretation.
• EMS field personnel remotely activate hospital catheterization labs only 40 percent of the time. This can significantly delay evaluation and treatment.
• Destination protocols are only used a third of the time to enable EMS to take STEMI patients directly to a hospital capable of providing primary PCI 24 hours a day, seven days a week. Instead, many EMS departments take patients to the closest hospital, which can cause significant delays to appropriate care.
• Only about 20 percent of hospitals are able to perform primary PCI 24 hours a day, seven days a week.

Robert E. O'Connor MD, chair of the AHA ML ECC task force said:

"We were encouraged that more EMS systems than anticipated had vehicles equipped with 12 lead ECGs, devices that diagnose STEMI and other heart attacks. However, we found the need for better systems to allow EMS to transmit data from ECGs and activate the cath lab on the way to the hospital and for policies allowing them to take patients to the facility able to provide appropriate care, whether it's the closest facility or not."

Other findings include:

• More paramedics should receive training on interpreting 12 lead ECGs.
• Funding is needed for additional 12 lead ECG devices and training.
• Information sharing between EMS and hospitals is poor, so it's difficult to track the quality of care a patient receives as they move from EMS to hospital-based care. Confidentiality requirements are hindering the process.

One gripe that I'm hearing already is that the AHA ML survey did not take into account tiered systems like King County Medic One. Apparently a minority of ambulances in that system are ALS (with 12 lead monitors) and yet it's one of the best EMS systems in the country.

That's a fair point! It doesn't matter whether or not every ambulance in the system has a 12 lead monitor. What matters is that ACS patients get an ambulance with a 12 lead monitor.