ECG Case n°1

A 75-year-old man is brought in Emergency Department by ambulance complaining of breathlessness and dyspnoea.

Medical History: Former smoker, COPD.

BP 133/77 mmHg, SpO2 96% room air, RR 22/min, GCS 15.

HR is fixed at 215 bpm. Is this SVT? ANRT? AVNRT? Atrial flutter? 

ECG. 1A-B

ABG room air: pH 7.391, pO2 95.4, pCO2 41.3, Hb 15.8 g/dL, K+ 5.3, Na+ 135, Ca2+ 1.14, Lac 2.2, Glu 152, HCO3- 25.

ECG ANSWER and INTERPRETATION

Rate:

  • 215

Rhythm:

  • Regular without P waves

Axis:

  • +90°

Intervals:

  • PR – No visible P waves
  • QRS – Normal (<120ms)
  • QT – 280ms (QTc Bazett 440ms)

Segments:

  • ST depression V3-6 and DIII-aVF

DIFFERENTIAL DIAGNOSIS

AVNRT– Regular 
– Rate ~140-280 bpm
– QRS complexes have a morphology that is usual for the subject under examination
– Narrow QRS complexes (< 120 ms) unless there is co-existing bundle branch block, accessory pathway, or rate-related aberrant conduction
– P waves if visible exhibit retrograde conduction with P-wave inversion.
– P waves if visible exhibit retrograde conduction with P-wave inversion in leads II, III, aVF. They may be buried within (more frequently), visible after, or very rarely visible before the QRS complex
– The atrial and ventricular rates are the same
– ST-segment depression may be observed
AVRT– Regular
– Rate 200-300 bpm
– QRS complexes have a morphology that is usual for the subject under examination
– Narrow QRS complexes (< 120 ms) unless there is co-existing bundle branch block, accessory pathway, or rate-related aberrant conduction
– P waves if visible exhibit retrograde conduction with P-wave inversion.
– Retrograde P waves are usually visible, with a long RP interval (P-QRS > QRS-P)QRS < 120ms unless pre-existing bundle branch block, or rate-related aberrant conduction
– The atrial and ventricular rates are the same
– ST-segment depression may be observed
Atrial Flutter– Narrow complex tachycardia
– Regular atrial activity at ~250-300 bpm (more frequently ~300 bpm)
– “Saw-tooth” pattern of P waves (typically in II, III, aVF, V1)
– Upright flutter waves in V1 that may resemble P waves
– Ventricular rate depends on AV conduction ratio; QRS rate is a fraction of the atrial rate (1/2 = 150 bpm; 1/3 = 100 bpm: 1/4 = 75 bpm)

OUTCOME

Flutter waves are not clearly seen (flutter with a 1:1 block?); Alternatively, this may just be rapid SVT (AVNRT/AVRT).

Given doubt regarding the rhythm, and a fixed heart rate of 220 bpm that is often seen in atrial flutter, we chose to administer adenosine to assist in differentiating/ treating the cause.

6 mg of adenosine was administered without benefit.

Then 12 mg of adenosine was administered.

ECG 2.

Rhythm strip reveals flutter waves. The patient does not cardiovert to sinus rhythm following adenosine administration; instead, the degree of AV block is increased, revealing sawtooth flutter waves.

Verapamil 5 mg 1 fl + Normal Saline 250 ml was administered, with good rate control

ECG 3.

INTERPRETATION:

ECG 1 A-B: Atrial Flutter 1:1 Block

ECG 3: Atrial Flutter 2:1 Block

  • Narrow Complex Tachycardia
  • Ventricular rate 120 bpm
  • Sawtooth flutter waves are seen in the inferior leads II, III, aVF.
  • Upright flutter waves in V1 appear either as pseudo-P waves or as notches in the T wave.
  • There is a clear 2:1 relationship between the flutter waves (300 bpm) and QRS complexes (120 bpm).

TRICKS

IMG. 1: Mechanism and electrocardiographic pattern of typical atrial flutter (left) and reverse typical atrial flutter (right). (1) 
 
Anticlockwise Reentry (typical atrial flutter) (2): (90% of cases of atrial flutter). Retrograde atrial conduction produces:
Inverted flutter waves in leads II,III, aVF
Positive flutter waves in V1 — may resemble upright P waves
 
 Clockwise Reentry (reverse typical atrial flutter) (2): This variant produces the opposite pattern:
Positive flutter waves in leads II, III, aVF (ECG. 1A-B,2,3)

AUTHORS

Dr. Lorenzo Pelagatti

Emergency Department – Nuovo Ospedale di Prato S. Stefano – Prato, Tuscany, Italy

High Dependency Unit – AOU Careggi – Florence, Tuscany, Italy


Dr. Franco Lai

Emergency Department – Nuovo Ospedale di Prato S. Stefano – Prato, Tuscany, Italy

REFERENCES

  1. F. García Cosío, A. Pastor, A. Núñez et al. Atrial Flutter: an Update Rev Esp Cardiol. 2006;59(8):816-31. DOI: 10.1016/S1885-5857(07)60047-4.
  2. Marine et al. Different Patterns of Interatrial Conduction in Clockwise and Counterclockwise Atrial Flutter. Circulation. 2001;104:1153–1157
  3. Jabbour F, Grossman SA. Atrioventricular Reciprocating Tachycardia. 2021 Aug 29. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 30969587.

SITOGRAPHY

  1. Dr Smith’s ECG Blog – Atrial Flutter
  2. https://litfl.com – Atrial Flutter, SVT, AVRT

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.