# NCLEX : ECG Analysis

## Example Questions

### Example Question #1 : Ecg Analysis

A client has just undergone an electrocardiogram (ECG), the nurse notes that the QRS complex is measured to be 0.09 seconds. What is the first action the nurse should take?

Place on a cardiac monitor to check for arrhythmias

Call the physician

The nurse should document this finding

The nurse should document this finding

Explanation:

This is a normal finding, the QRS should have a duration between 0.6-0.12 seconds.

### Example Question #1 : Ecg Analysis

You are taking care of an elderly patient who is hospitalized for sudden onset of severe, diffuse abdominal pain out of proportion to the patient's abdominal physical exam that is also accompanied by rectal bleeding and palpitations. You obtain an ECG and notice a tachycardic, irregularly irregular rhythm without any distinct P waves. Which of the following is the most likely cardiac rhythm seen on this patient's ECG?

Complete heart block

Sick sinus syndrome

First-degree heart block

Atrial fibrillation (A-fib)

Atrial flutter

Atrial fibrillation (A-fib)

Explanation:

The most likely cardiac rhythm on this patient's ECG is atrial fibrillation

Atrial fibrillation is a tachyarrhythmia that is characterized on ECG by absence of distinct P waves, oscillating "f" waves that cause an irregular baseline rhythm, and abnormal, inconsistent R-R intervals that produce an irregularly irregular rhythm.

When a patient is in atrial fibrillation, the patient may be asymptomatic, but at other times, the patient may complain of a rapid heartbeat, or a feeling of uneasiness. The clues in this case that the patient is in atrial fibrillation are that the ECG shows the characteristic irregularly irregular rhythm, with an absence of any distinct P waves.

Clinically, the other clues are that the patient is complaining of palpitations while simultaneously experiencing sudden onset of severe, diffuse abdominal pain that is out of proportion to the abdominal physical exam, and is accompanied by rectal bleeding. This is very consistent with mesenteric ischemia (a condition in which a patient, typically in atrial fibrillation, projects a blood clot to one of the mesenteric vessels, causing ischemia to the bowel served by the affected vessel). While, this was not asked in the question explicitly, and the question could be answered without this knowledge, this helps confirm the diagnosis if you are aware of it.

The other answers are incorrect for the following reasons:

1) Atrial flutter typically presents with a "sawtooth" waveform and has more regularity in wavelength.

2) Sick sinus syndrome is also known as tachy-brady syndrome, indicating that the patient has frequent fluctuations between tachycardia and bradycardia. In this instance, we have ECG findings that are very consistent with atrial fibrillation and show no evidence of bradycardia.

3) First-degree heart block and complete heart block are each typically characterized by bradycardia rather than tachycardia, and do not appear like atrial fibrillation on ECG.

### Example Question #2 : Ecg Analysis

A patient presents with thirty minute history of substernal chest pain that radiates to his left jaw. Which of the following EKG changes would you expect in this patient if his troponin level came back positive at ?

PR widening

ST elevation

ST depression

QT prolongation

PR shortening

ST elevation

Explanation:

Substernal chest pain that radiates to the jaw is classic of myocardial infarction. Elevated troponin and EKG changes help confirm the diagnosis (reference levels are about . ST segment elevation is classically seen in myocardial infarctions that result in positive troponin.

### Example Question #1 : Ecg Analysis

You are a nurse taking care of a patient in the emergency room. Among other acute labwork and imaging, you obtain an electrocardiogram (ECG) of the patient. The ECG shows Osborn waves. Which of the following is the most common cause of Osborn waves on ECG?

Carbon monoxide poisoning

Hypothermia

Hyperthermia

Ethanol toxicity

Hypothermia

Explanation:

The correct answer is "hypothermia." Osborn waves on electrocardiogram are the pathognomonic finding associated with hypothermia (to a core body temperature of lower than 32 C). Osborn waves are observed as upward deflections in the ECG reading between the QRS and ST intervals with an elevation at the S point (which is sometimes also referred to as the J point). While hypothermia is the most common cause of Osborn waves, they may also be observed in patients with coronary vasospasm, hypercalcemia, ventricular fibrillation, or brain trauma.

Neither hyperthermia, ethanol toxicity, carbon monoxide poisoning, nor lead poisoning are associated with Osborn waves on ECG.

### Example Question #1 : Ecg Analysis

An EKG of your patient shows peaked T-waves. This finding correlates to which electrolyte abnormality?

High potassium

High sodium

Low potassium

Low sodium

High calcium

High potassium

Explanation:

Peaked T-waves are a warning sign for elevated levels of potassium in the body. On the other hand, flattened T-waves are potentially indicative of low levels of potassium. Hyperkalemia (high potassium) is a potentially dangerous condition that can lead to cardiac abnormalities and potentially death.

### Example Question #1 : Ecg Analysis

What is the most common EKG finding in a patient with a pulmonary embolism?

ST depression

Sinus tachycardia

ST elevation