Palpitations that started suddenly during a lesson

Primary school teacher, well, no medication apart from the contraceptive pill. Two similar episodes in the past two years, both stopping on their own within twenty minutes. Two coffees this morning, no alcohol, not pregnant.

Stage 1 of 2

Aoife Ní Chearbhaill is alert and talking, aware of her heart pounding in her neck, with no chest pain and no breathlessness at rest. It began instantly, mid-sentence, forty minutes ago. Chest is clear and the pulse is regular and too fast to count. This tracing was recorded as she arrived.

Tracing 1 of 2 for the quiz “Palpitations that started suddenly during a lesson”. — Twelve-lead on arrival, 25 mm/s, 10 mm/mV. Open this tracing in the studio

What is the rhythm?

AAtrial flutter with 2:1 conduction Your answer
BAtrial fibrillation with a rapid ventricular response Your answer
CAV nodal re-entrant tachycardia Correct answer Your answer
DSinus tachycardia Your answer

Which feature on the paper supports it?

AA small extra deflection at the end of the QRS in V1 Correct answer Your answer
BThe rate of 184 Your answer
CThe regularity of the rhythm Your answer
DThe narrow QRS complexes Your answer

Stage 2 of 2

A modified Valsalva manoeuvre does nothing. Adenosine 6 mg is given by rapid push through a large cannula with the rhythm recording, she flushes and describes a horrible few seconds, and the rhythm stops. This tracing was taken once she had settled.

Tracing 2 of 2 for the quiz “Palpitations that started suddenly during a lesson”. — Twelve-lead after conversion, 25 mm/s, 10 mm/mV. Open this tracing in the studio

Observations

HR: 78
SpO₂ (%): 99
Respiratory rate: 16
Temperature (°C): 36.6
Systolic BP (mmHg): 118
Diastolic BP (mmHg): 74

What does comparing the two tracings show?

AThe ST changes of the tachycardia have resolved, confirming ischaemia Your answer
BShe had a rate-related bundle branch block that has now resolved Your answer
CThe QRS has narrowed since the tachycardia stopped Your answer
DThe extra deflection in V1 has gone, so it was a retrograde P wave Correct answer Your answer

What do you tell her about the future?

ALifelong beta blockade, since the rhythm will otherwise return Your answer
BTeach her the manoeuvre, and refer for ablation if episodes continue Correct answer Your answer
CAnticoagulation, because of the stroke risk from the arrhythmia Your answer
DAvoid exertion and caffeine, which are what trigger the circuit Your answer

Palpitations that started suddenly during a lesson

The case

On arrival

Observations

Diagnosis

Discussion