Normal sinus rhythm on a 12-lead ECG.
Electrocardiogram (ECG) tracing showing multiple leads (I, II, III, aVR, aVL, aVF, V1-V6) with regular heart rhythm and normal P waves, QRS complexes, and T waves.
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Step-by-step solution for: EKG practice test - ECG Quiz
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Show Answer Key & Explanations
Step-by-step solution for: EKG practice test - ECG Quiz
Based on the provided ECG image, here is a detailed analysis and solution:
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This is a 12-lead electrocardiogram (ECG) showing a regular, narrow-complex tachycardia.
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## 🔍 Key Observations
- Regular rhythm: All R-R intervals are consistent across all leads.
- Rate: Approximately 150–160 bpm (calculated by counting R waves in 6 seconds and multiplying by 10 — e.g., ~15–16 QRS complexes in 6 sec → 150–160 bpm).
- Narrow QRS complexes: All QRS durations are < 120 ms (less than 3 small boxes), indicating supraventricular origin.
- Absent or hidden P waves: In most leads, especially II, III, aVF, V1–V6, there are no clearly visible distinct P waves preceding each QRS complex.
- In lead V1, there may be subtle notches or deformities in the terminal portion of the QRS or ST segment — possibly suggesting retrograde P waves buried within the QRS or T wave.
- In leads II, III, aVF, there is a slight downward deflection just after the QRS — again, suggestive of retrograde atrial activation.
- Normal axis: QRS positive in I and aVF → normal frontal plane axis.
- No significant ST elevation/depression or T-wave inversion to suggest acute ischemia.
- Mild nonspecific ST-T changes may be present but not diagnostic.
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## 🧠 Diagnosis
The ECG shows Supraventricular Tachycardia (SVT), most likely Atrioventricular Nodal Reentrant Tachycardia (AVNRT).
- Regular narrow-complex tachycardia at ~150–160 bpm.
- Absent or buried P waves — classic for AVNRT.
- Retrograde P waves may be seen as pseudo-r’ in V1 or pseudo-s waves in inferior leads (II, III, aVF).
Other possibilities:
- Atrial Flutter with 2:1 conduction: Usually has “sawtooth” flutter waves, which are not seen here.
- Atrial Tachycardia: Typically has visible P waves with different morphology from sinus P waves — not seen here.
- AVRT (WPW): Would show delta waves in sinus rhythm; none present here.
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## ✔ Final Diagnosis
> Supraventricular Tachycardia (SVT), most likely Atrioventricular Nodal Reentrant Tachycardia (AVNRT)
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## 💊 Clinical Implications & Management
- Stable: Try vagal maneuvers (e.g., Valsalva, carotid sinus massage).
- Unstable (hypotension, chest pain, altered mental status): Immediate synchronized cardioversion.
- Adenosine 6 mg IV bolus (first-line) → often terminates AVNRT.
- If adenosine fails: consider verapamil, diltiazem, or beta-blockers (avoid in WPW if pre-excitation suspected).
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## 📌 Summary
| Feature | Finding |
|---------------------|----------------------------------|
| Rhythm | Regular |
| Rate | ~150–160 bpm |
| QRS width | Narrow (<120 ms) |
| P waves | Absent/buried |
| Axis | Normal |
| Diagnosis | SVT (likely AVNRT) |
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✔ This ECG represents a common, treatable arrhythmia. Recognition of the absence of clear P waves and regular narrow-complex tachycardia is key to diagnosing AVNRT.
Let me know if you’d like a step-by-step guide on how to calculate heart rate or identify P waves in SVT!
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ECG Interpretation
This is a 12-lead electrocardiogram (ECG) showing a regular, narrow-complex tachycardia.
---
## 🔍 Key Observations
1. Rhythm
- Regular rhythm: All R-R intervals are consistent across all leads.
- Rate: Approximately 150–160 bpm (calculated by counting R waves in 6 seconds and multiplying by 10 — e.g., ~15–16 QRS complexes in 6 sec → 150–160 bpm).
- Narrow QRS complexes: All QRS durations are < 120 ms (less than 3 small boxes), indicating supraventricular origin.
2. P Waves
- Absent or hidden P waves: In most leads, especially II, III, aVF, V1–V6, there are no clearly visible distinct P waves preceding each QRS complex.
- In lead V1, there may be subtle notches or deformities in the terminal portion of the QRS or ST segment — possibly suggesting retrograde P waves buried within the QRS or T wave.
- In leads II, III, aVF, there is a slight downward deflection just after the QRS — again, suggestive of retrograde atrial activation.
3. Axis
- Normal axis: QRS positive in I and aVF → normal frontal plane axis.
4. ST-T segments
- No significant ST elevation/depression or T-wave inversion to suggest acute ischemia.
- Mild nonspecific ST-T changes may be present but not diagnostic.
---
## 🧠 Diagnosis
The ECG shows Supraventricular Tachycardia (SVT), most likely Atrioventricular Nodal Reentrant Tachycardia (AVNRT).
Why AVNRT?
- Regular narrow-complex tachycardia at ~150–160 bpm.
- Absent or buried P waves — classic for AVNRT.
- Retrograde P waves may be seen as pseudo-r’ in V1 or pseudo-s waves in inferior leads (II, III, aVF).
Other possibilities:
- Atrial Flutter with 2:1 conduction: Usually has “sawtooth” flutter waves, which are not seen here.
- Atrial Tachycardia: Typically has visible P waves with different morphology from sinus P waves — not seen here.
- AVRT (WPW): Would show delta waves in sinus rhythm; none present here.
---
## ✔ Final Diagnosis
> Supraventricular Tachycardia (SVT), most likely Atrioventricular Nodal Reentrant Tachycardia (AVNRT)
---
## 💊 Clinical Implications & Management
If patient is:
- Stable: Try vagal maneuvers (e.g., Valsalva, carotid sinus massage).
- Unstable (hypotension, chest pain, altered mental status): Immediate synchronized cardioversion.
Pharmacologic options (if stable):
- Adenosine 6 mg IV bolus (first-line) → often terminates AVNRT.
- If adenosine fails: consider verapamil, diltiazem, or beta-blockers (avoid in WPW if pre-excitation suspected).
---
## 📌 Summary
| Feature | Finding |
|---------------------|----------------------------------|
| Rhythm | Regular |
| Rate | ~150–160 bpm |
| QRS width | Narrow (<120 ms) |
| P waves | Absent/buried |
| Axis | Normal |
| Diagnosis | SVT (likely AVNRT) |
---
✔ This ECG represents a common, treatable arrhythmia. Recognition of the absence of clear P waves and regular narrow-complex tachycardia is key to diagnosing AVNRT.
Let me know if you’d like a step-by-step guide on how to calculate heart rate or identify P waves in SVT!
Parent Tip: Review the logic above to help your child master the concept of ekg practice worksheets with answers.
