Accelerated idioventricular rhythm after gastric dilatation-volvulus
5-year-old Great Dane, 18 hours after gastropexy for gastric dilatation-volvulus. He is alert, with pink mucous membranes, strong pulses and a systolic pressure of 125 mmHg. ECG monitor:
| Parameter | Result | Reference |
|---|---|---|
| Heart rate | 130 bpm (preceding sinus rate 120 bpm) | 60–140 bpm |
| Rhythm | Runs of wide complexes alternating with sinus rhythm | Sinus |
| QRS | 0.09 s, uniform morphology | ≤ 0.06 s |
| Other findings | Fusion complexes at the transitions; no R-on-T | — |
| Potassium | 3.3 mmol/L | 3.5–5.5 |
What is the most appropriate next step?
chevron_right Show answer and explanation
A. IV lidocaine bolus followed by a constant rate infusion
This is a well-tolerated accelerated idioventricular rhythm: the rate is similar to the sinus rate and the dog is well perfused. Suppressing it brings no benefit and risks adverse effects.
B. Monitor without antiarrhythmics and correct hypokalaemia, pain, hypovolaemia and hypoxaemia
Correct. Uniform wide QRS complexes at a rate similar to the sinus rate, with fusion complexes and no haemodynamic compromise: this is an accelerated idioventricular rhythm. It usually resolves within 24–72 hours once triggering factors are corrected.
C. Synchronised electrical cardioversion
Cardioversion is reserved for unstable tachyarrhythmias. This rhythm is slow, stable and transient, and does not justify it.
D. Oral sotalol to prevent sudden death
There is no indication for a chronic antiarrhythmic in a transient, benign postoperative arrhythmia; the beta-blocking effect would be harmful in the immediate postoperative period.
lightbulb Key takeaway
Accelerated idioventricular rhythm (wide QRS complexes at a rate similar to and competing with the sinus rate) is typical after GDV, splenectomy and trauma. Treat it only if the rate rises above 180 bpm, R-on-T appears, it becomes multiform, or there is hypotension.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.