Dropped beats in a patient on beta-blocker therapy
A 74-year-old woman is admitted to a medical ward with two episodes of syncope and persistent dizziness. Her regular medicines include metoprolol 50 mg twice daily and diltiazem 60 mg three times daily. On examination she is pale and clammy; blood pressure is 96/60 mmHg, respiratory rate 20/min, and oxygen saturation 96% on room air. The monitor shows a heart rate of 36/min. A 12-lead ECG is recorded: P waves are regular at about 92/min, QRS complexes are regular at about 36/min, and there is no consistent PR interval. The QRS complexes are wide at 0.14 s. The ECG machine's automated report says 'sinus bradycardia, otherwise normal ECG.' The patient has vomited once and is confused about the date. The nurse asks the technician to file the report and take the patient back to the ward because the doctor is busy.
1. Identify the rhythm and explain why the automated report is unsafe.
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The rhythm is complete (third-degree) atrioventricular block. The P waves are regular at about 92/min, the QRS complexes are regular at about 36/min, and there is no consistent PR interval because atrial and ventricular activity are dissociated. The wide QRS at 0.14 s suggests a ventricular or infranodal escape rhythm, which is more hazardous than a narrow-complex junctional escape. The automated report of 'sinus bradycardia' is unsafe because it recognises slow rate but misses AV dissociation. The patient has syncope, hypotension, clamminess, vomiting, and confusion, so this is not a benign tracing. The technician must treat the ECG as an emergency finding, not as a routine report.
2. What immediate actions should the technician take, and what should not be done?
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Do: stay with the patient, call the medical emergency team or senior nurse immediately, keep continuous cardiac monitoring attached, repeat blood pressure, and prepare the resuscitation trolley and pacing pads as local protocol directs. Hand over the tracing personally and state clearly: 'P waves at 92, QRS at 36, no PR relationship, wide QRS, patient has syncope and hypotension.' Document the time and who was informed.
Do not: file the report as normal, send the patient back to the ward without medical review, or rely on the automated 'sinus bradycardia' label. The technician should not give drugs independently, but should not delay escalation while waiting for the doctor to become free.
3. Which features suggest a high-risk block, and why does that change urgency?
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The high-risk features are syncope, persistent dizziness, hypotension, wide QRS escape at 0.14 s, and a very slow ventricular rate of 36/min. A wide-complex escape suggests block below the AV node, where atropine is less likely to help and progression to asystole or ventricular arrhythmia is a real risk. The patient's confusion, vomiting, and clamminess indicate poor perfusion. These features change the urgency from 'routine ECG review' to 'immediate medical assessment and preparation for pacing.' The technician's role is to recognise the pattern, escalate without delay, and communicate the specific findings rather than simply handing over paper.