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
- 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.
- Marine et al. Different Patterns of Interatrial Conduction in Clockwise and Counterclockwise Atrial Flutter. Circulation. 2001;104:1153–1157
- Jabbour F, Grossman SA. Atrioventricular Reciprocating Tachycardia. 2021 Aug 29. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 30969587.
SITOGRAPHY
- Dr Smith’s ECG Blog – Atrial Flutter
- https://litfl.com – Atrial Flutter, SVT, AVRT
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