Mixed Deck — All ECG Topics Flashcards

If the limb leads on the right and left arms are reversed, what change is commonly seen?

Answer: Lead I becomes inverted

Right/left arm lead reversal typically inverts lead I and can mimic pathology.

The nurse looks at an ECG strip, detects a Q wave, and determines that this waveform is

Answer: Only visible if pathology is present.

While small, narrow Q waves can be a normal variant in some leads, the presence of a *significant* or pathological Q wave (wider than 0.04 seconds or deeper than 25% of the R wave amplitude) is a hallmark of myocardial infarction. In a clinical setting, when a nurse 'detects a Q wave,' the primary concern often shifts to assessing if it represents this critical pathology, making its visibility a strong indicator of past cardiac damage.

What is the maximum safe leakage current from an ECG machine to the patient?

Answer: 10 µA (microamperes) for applied part in cardiac floating connection

IEC 60601 limits patient auxiliary current (leakage) to 10 µA for cardiac floating-type connections, since even tiny currents can induce ventricular fibrillation if they reach the heart directly.

Peaked, narrow, symmetrical T-waves in multiple leads are a classic ECG sign of:

Answer: Hyperkalemia (early sign)

Tall, peaked, narrow, symmetrical T-waves are an early ECG manifestation of hyperkalemia, reflecting altered ventricular repolarization from elevated extracellular potassium.

A patient taking amiodarone is most likely to show which ECG finding?

Answer: Prolonged QT interval

Amiodarone prolongs ventricular repolarization, resulting in a prolonged QT interval on the ECG.

A patient receiving IV procainamide (Class IA) for ventricular arrhythmia may develop which dangerous ECG pattern?

Answer: QRS widening greater than 50% of baseline

Procainamide can widen the QRS by more than 50% of the baseline width, signaling toxicity and increased risk of proarrhythmia.

Before applying chest electrodes, the technician should:

Answer: Clean and prep the skin site

Skin should be cleaned and prepped to ensure good electrode contact.

Which patient position is standard for recording a routine resting 12-lead ECG?

Answer: Supine (lying flat on the back)

A routine ECG is recorded with the patient lying supine and relaxed to minimize artifact.

T-wave inversion in leads V1–V4 in an adult is most concerning for:

Answer: Anterior ischemia or right heart strain

T-wave inversions in the anterior precordial leads (V1–V4) can indicate anterior wall ischemia, non-STEMI, or right ventricular strain and require clinical correlation.

Which precaution is essential when performing an ECG near an MRI suite?

Answer: Do not bring ferromagnetic ECG equipment into the MRI environment zone

Ferromagnetic objects can become dangerous projectiles in the MRI magnetic field; only MRI-compatible ECG equipment should be used in or near an MRI suite.

How many electrodes are placed on the body to record a standard 12-lead ECG?

Answer: 10

Ten electrodes (four limb and six chest) produce the 12 leads of a standard ECG.

Which way does lead II go on an ECG?

Answer: 60 degrees

In the standard limb lead configuration (Einthoven's triangle), Lead II is an inferior lead that runs from the right arm (negative) to the left leg (positive). It is oriented at an angle of +60 degrees on the frontal plane, making it a crucial lead for assessing the heart's electrical axis and inferior wall changes.

Why is proper skin preparation important before applying ECG electrodes?

Answer: To reduce skin impedance and ensure good electrical contact for accurate signal recording

Cleaning the skin with alcohol, removing excess hair, and mildly abrading the surface reduces skin impedance, ensuring good electrode contact and minimizing artifact in the ECG recording.

Blood rich in oxygen is delivered to the right atrium.

Answer: FALSE

This statement is false. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava. Oxygen-rich blood, after being oxygenated in the lungs, returns to the *left* atrium via the pulmonary veins, from where it is then pumped to the rest of the body.

A patient receiving IV adenosine for SVT would most likely show which transient ECG finding immediately after the dose?

Answer: Complete heart block or brief asystole

Adenosine transiently blocks AV node conduction, often producing a brief period of complete heart block or asystole before normal rhythm resumes.

A corrected QT interval (QTc) is calculated to account for:

Answer: Heart rate variation

QT interval lengthens at slower heart rates and shortens at faster rates; the QTc corrects for this, allowing comparison across different heart rates using Bazett's formula.

Which filter setting on an ECG machine is used to reduce muscle artifact?

Answer: Low-pass filter

A low-pass filter cuts high-frequency signals such as muscle (EMG) artifact, producing a cleaner ECG tracing.

What is the significance of a pathological Q wave on an ECG?

Answer: It may represent transmural myocardial infarction (scar tissue)

Pathological Q waves (≥40 ms wide or ≥25% of the QRS height) represent areas of electrically silent myocardium, typically indicating old transmural infarction.

Which of the following best describes atrial fibrillation on an ECG?

Answer: Irregularly irregular rhythm with no distinct P waves

Atrial fibrillation shows an irregularly irregular ventricular response with absent discrete P waves.

How do you differentiate between ventricular tachycardia and supraventricular tachycardia with aberrancy?

Answer: VT shows AV dissociation, fusion/capture beats, and concordance; SVT with aberrancy usually has preceding P waves

Key VT indicators include AV dissociation, fusion/capture beats, extreme axis deviation, and QRS concordance. SVT with aberrancy typically shows preceding atrial activity and a bundle branch block pattern.