SVT is Not a Rhythm

The Paramedic Practitioner

http://www.cmaj.ca/content/188/17-18/E466

Mechanism of Slow-Fast AVNRT
http:// https://litfl.com/supraventricular-tachycardia-svt-ecg-library/

AVNRT versus AVRT
http:// https://litfl.com/supraventricular-tachycardia-svt-ecg-library/

Sinus tachycardia with P waves at the end of the T-wave. Theses can be less obvious and the EKG can be mistaken for AVNRT or AVRT
http:// https://litfl.com/sinus-tachycardia-ecg-library/

Atrial fibrillation with rapid ventricular response. Not the lack of visible P waves and irregularity that make the diagnosis.
http:// https://litfl.com/atrial-fibrillation-ecg-library/

Atrial flutter with 2:1 conduction. Rate of 150 and fairly obvious flutter waves are present.

Atrial flutter with 2:1 conduction. Flutter waves are not overtly obvious, but the rate of 150 bpm helps suggest atrial flutter. Treatment with diltiazem will slow conduction and help reveal the flutter waves and treat the rate.

Atrial flutter with 1:1 conduction. The rate of 300 and regularity of QRS complexes helps confirm the diagnosis.
http:// https://litfl.com/atrial-flutter-ecg-library/

AVNRT. A regular, narrow-complex tachycardia without obvious P-waves.
http:// https://litfl.com/supraventricular-tachycardia-svt-ecg-library/

AVRT in a patient with WPW. A regular, narrow-complex tachycardia without obvious P-waves.
http:// https://litfl.com/pre-excitation-syndromes-ecg-library/

Junctional tachycardia. Retrograde P-waves are obvious before the QRS complexes but they are not always visible.
http:// https://litfl.com/accelerated-junctional-rhythm-ajr/

Atrial fibrillation with WPW. Note the extremely rapid rate, 300 bpm at times, the wide QRS complexes and varying QRS morphologies. These features confirm the diagnosis.

Another example of atrial fibrillation with WPW. This is difficult to distinguish from polymorphic ventricular tachycardia.
http:// https://litfl.com/pre-excitation-syndromes-ecg-library/

1. Patient sitting upright on stretcher
2. Patient blows into syringe for 15 seconds
3. At 15 seconds quickly lay patient supine and elevate the legs
http:// https://rebelem.com/the-revert-trial-a-modified-valsalva-maneuver-to-convert-svt/

Reference:

https://litfl.com/supraventricular-tachycardia-svt-ecg-library/

https://litfl.com/pre-excitation-syndromes-ecg-library/

https://rebelem.com/the-revert-trial-a-modified-valsalva-maneuver-to-convert-svt/

Alabed S, Sabouni A, Providencia R, Atallah E, Qintar M, Chico TJ. Adenosine versus intravenous calcium channel antagonists for supraventricular tachycardia. Cochrane Database Syst Rev. 2017 Oct 12;10:CD005154. doi: 10.1002/14651858.CD005154.pub4.

Appelboam A, Reuben A, Mann C, Gagg J, Ewings P, Barton A, Lobban T, Dayer M, Vickery J, Benger J; REVERT trial collaborators. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet. 2015 Oct 31;386(10005):1747-53. doi: 10.1016/S0140-6736(15)61485-4.

Bibas L, Levi M, Essebag V. Diagnosis and management of supraventricular tachycardias. CMAJ. 2016;188(17-18):E466–E473. doi:10.1503/cmaj.160079

Hafeez Y, Armstrong TJ. Atrioventricular Nodal Reentry Tachycardia (AVNRT) [Updated 2019 May 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499936/