CASE 03 / CARDIAC EMERGENCIES
Supraventricular Tachycardia
Heart rate 190. Borderline blood pressure. The team must decide how to intervene.
10-minute scenario | 10-15-minute debrief | Low-tech
Why run this case?
Regular narrow-complex tachycardia is common; deciding whether the rhythm is poorly tolerated is the crucial judgement. In a small rural department, success also depends on finding adenosine, administering it correctly and preparing a rescue plan.
Learning objectives
Recognize worsening perfusion from a primary tachyarrhythmia and prepare urgent rhythm conversion.
Deliver 6 mg then 12 mg adenosine by rapid IV push and immediate flush when a short trial will not delay cardioversion.
Communicate a synchronized-cardioversion contingency and identify one local medication or equipment workflow issue.
Set up
Use your usual resuscitation bay, basic mannequin, monitor/defibrillator, pads, IV supplies and simulated adenosine. Let the team locate its own stopcock, flushes and medication stock.
The Scenario
A 46-year-old woman presents after 35 minutes of sudden palpitations, lightheadedness and central chest pressure. She is alert but clammy.
HR 188 regular | BP 96/62 | RR 24 | SpO2 97% RA
Run the case
STAGE 01 · 0–3 MIN
Recognize the rhythm
Regular narrow SVT, chest pressure and soft BP.
Facilitator focus: Roles, monitoring, IV, early pads, rapid stability assessment. A quick modified Valsalva fails.
STAGE 02 · 3-7 MIN
Treat and prepare a rescue
BP falls to 84/52, chest pressure worsens. Adenosine 6 mg produces transient AV block but SVT recurs. A second 12 mg dose converts. If delayed and perfusion worsens, synchronized cardioversion is the correct pathway.
Facilitator focus: Rapid adenosine administration, reassessment after the first dose, recognition of persistent SVT, and timely escalation to 12 mg. Monitor for deterioration requiring synchronized cardioversion.
STAGE 03 · 7-10 MIN
Reassess and plan
Sinus rhythm at 96 then 88/min, BP 112/72, symptoms resolve. Repeat ECG, reassess, plan observation, investigation and follow-up or transfer.
Facilitator focus: Confirm conversion, reassess hemodynamic stability, and discuss monitoring and disposition. Identify any medication access or workflow issues encountered during resuscitation.
Debrief
Keep it practical. Focus on one or two clinical decisions and what the case revealed about your department.
01 / Reactions
How did that feel? When did the case become urgent?
02 / Clinical decisions
Why adenosine, and when would you shock? What alternatives suit a genuinely stable patient?
03 / Systems
Where is adenosine stored? Can we prepare the rapid flush quickly?
04 / Takeaway
What is one thing you will do differently next time?
What we learned in Espanola
Knowing what medication to give is one thing. Knowing where to find it is another.
Adenosine is in the Pyxis, not the crash cart. The session helped the team work through rapid medication retrieval, stopcock/flush technique and role assignment.
The point: test the system, not just the learner.
Clinical takeaways
In SVT, treat the patient, not just the heart rate. Hypotension, ischemic chest discomfort, altered mental status or shock attributable to the tachycardia should prompt preparation for synchronized cardioversion.
For regular narrow-complex SVT, consider vagal manoeuvres and adenosine (6 mg rapid IV push, followed by 12 mg if needed), provided they do not delay cardioversion in a deteriorating patient. Use a proximal IV, rapid saline flush and continuous ECG monitoring.
Diltiazem or verapamil are effective alternatives in appropriately selected, hemodynamically stable patients, but may worsen hypotension.
Remember WPW: Adenosine can terminate regular orthodromic AVRT, but AV-nodal blockers are dangerous in pre-excited atrial fibrillation, where they may precipitate ventricular fibrillation. Avoid them when pre-excited AF is suspected.