ECG Review Flashcards

Study Notes

Components of ECG

ECG consists of P wave, PR segment, QRS complex, T wave, and ST segment.

P Wave

First wave in ECG sequence, indicating atrial depolarization.
Typically shows an upward deflection.

PR Segment

Represents electrical inactivity between P wave and QRS complex.
Indicates conduction delay between AV node and Bundle of HIS, allowing atrial contraction before ventricular contraction.
May be indistinguishable at high heart rates.

QRS Complex

Reflects ventricular depolarization; larger than P wave due to greater ventricular muscle mass.
Shows speed and direction of electrical impulse through ventricles; wide QRS signifies poor conduction and pumping strength.

QRS Appearance

Q wave is present if the first deflection points downward.
R wave denotes the first upward deflection in the complex.
S wave follows R wave with a downward deflection.

T Wave

Represents ventricular repolarization; heart reset for receiving new impulses.
Cannot respond to another impulse until repolarization finishes; may appear elevated or inverted.

ST Segment

Lies between the end of the QRS complex and the beginning of the T wave.
Should align with the baseline in a healthy heart rhythm.

Interpreting ECG

Key assessment questions:
- What is the heart rate?
- Is the rhythm regular?
- Is the QRS complex wide?
- Does every QRS have a corresponding P wave?

Importance of Heart Rate

LifeVest monitors heart rate as one of three criteria for identifying treatable arrhythmias.
Treatment thresholds are evaluated for ventricular tachycardia (VT) and ventricular fibrillation (VF) based on heart rate.

Six Second Strip Method

Count number of QRS complexes over a six-second interval.
Multiply the count by ten to estimate heart rate.

Rhythm Regularity

Examine R-R intervals, the distance between R waves.
Consistent R-R intervals indicate a regular rhythm, crucial for diagnosing arrhythmias.

Measuring QRS Width

Wide QRS complex suggests the rhythm may originate in the ventricles.
QRS width measured from the start of Q or R wave to the end of S wave.

Calculating QRS Width

Count small boxes between Q (or R) and S waves; multiply by 0.04 seconds.
Each small box represents 0.04 seconds.

Normal QRS

A normal QRS width is ≤ 0.12 seconds (3 small boxes).
Indicates electrical impulses come from above the ventricles through the AV node.

Wide QRS

Defined as QRS width > 0.12 seconds (3 small boxes).
Can result from conduction delays in ventricles or originate from ventricles themselves.
The association of P waves and the QRS width aids in diagnosing the cause.

Associating QRS and P Wave

Check if each QRS complex is preceded by a P wave.
Ensure consistency of the PR interval between complexes.
Relationship between QRS and P wave, along with QRS width, helps infer the rhythm's origin.

Description

Test your knowledge on the components of ECG with these flashcards. Each card focuses on fundamental aspects such as the P Wave and PR segment, essential for understanding cardiac electrical activity. Perfect for med students and healthcare professionals.

ECG Review Flashcards

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Questions and Answers

What are the components of ECG?

What does the P Wave represent?

What occurs during the PR segment?

What does the QRS complex represent?

What is indicated by a wide QRS?

What does the T wave represent?

What is the ST segment?

The _____ uses heart rate as one of three criteria to identify treatable arrhythmias.

How do you calculate heart rate using the Six Second Strip Method?

What do you assess to determine if the rhythm is regular?

What indicates a QRS complex is wide?

How is the width of the QRS complex calculated?

What indicates a normal QRS width?

What must be verified to assess if every QRS is associated with a P wave?