Rhythm strip flash card practice | MonitorTech.org - Free Printable

The image you've provided appears to be a segment of an electrocardiogram (ECG or EKG) tracing. Let's analyze it step by step to interpret the cardiac rhythm.

Step 1: Understand the ECG Paper

- The ECG paper has small squares (1 mm × 1 mm) and large squares (5 mm × 5 mm).
- Each small square represents 0.04 seconds horizontally.
- Each large square represents 0.2 seconds.
- Vertically, each small square is 0.1 mV, and each large square is 0.5 mV.

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Step 2: Identify Key Components

We look for:
- P waves: Atrial depolarization.
- QRS complexes: Ventricular depolarization.
- T waves: Ventricular repolarization.
- PR interval: From start of P wave to start of QRS.
- QT interval: From start of QRS to end of T wave.
- R-R intervals: Time between successive R waves (used to calculate heart rate).

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Step 3: Analyze the Tracing

Looking at your ECG:

1. Regular Rhythm?
- The R-R intervals appear regular — the distance between successive R waves is consistent.
- This suggests a regular rhythm.

2. Presence of P Waves?
- There are no visible P waves before the QRS complexes.
- Instead, there are sharp, narrow QRS complexes occurring regularly.

3. QRS Complexes:
- The QRS complexes are narrow (less than 0.12 seconds), indicating that the impulse originated in the atria or AV node, not from a ventricular source.

4. Heart Rate:
- Count the number of large squares between two R waves.
- In this case, there are approximately 3 large squares between R waves.
- Since one large square = 0.2 seconds, 3 large squares = 0.6 seconds.
- Heart rate = 60 / 0.6 = 100 beats per minute (bpm).

5. No P waves, but regular narrow QRS complex with normal rate:
- This pattern is typical of junctional rhythm.
- In junctional rhythm, the AV node acts as the pacemaker, bypassing the atria.
- Therefore, P waves are absent or inverted (if present), and the QRS is narrow because the impulse travels normally through the ventricles.

6. Is it sinus rhythm?
- No, because P waves are missing.
- Sinus rhythm requires P waves preceding each QRS complex.

7. Could it be atrial fibrillation?
- No, because the rhythm is regular, and there are no irregularly shaped fibrillatory waves.

8. Could it be ventricular tachycardia?
- Unlikely, because the QRS complexes are narrow, and VT typically shows wide QRS complexes (>0.12 sec).

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Final Diagnosis:

This ECG shows:
- Regular rhythm
- Narrow QRS complexes
- Absent P waves
- Normal heart rate (~100 bpm)

➡️ This is consistent with junctional rhythm (also known as nodal rhythm).

Additional Notes:

- Junctional rhythms can be physiological (e.g., in athletes) or pathological (e.g., due to AV nodal re-entry, drug effects, or ischemia).
- If the rate is <60 bpm, it’s called junctional bradycardia; if >100 bpm, it’s junctional tachycardia.
- Here, the rate is about 100 bpm, so it could be classified as junctional tachycardia.

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Summary:

✔ Diagnosis: Junctional Rhythm (possibly junctional tachycardia)
✔ Features:
- Regular rhythm
- Narrow QRS complexes
- Absent P waves
- Heart rate ~100 bpm

If this were a clinical setting, further evaluation (like a 12-lead ECG, history, and vital signs) would be needed to determine the cause and whether treatment is required.

Let me know if you'd like help calculating exact rates or identifying other features!