ECG Case 138
Three months of palpitations
A 62-year-old woman presents with three months of feeling like her ‘heartbeat is stumbling’, with an occasional sensation that it stops.
No cardiac history. Drinks four coffees a day. No syncope, no chest pain, no breathlessness.
OBSERVATIONS ON ARRIVAL
| HR | 60 |
| SpO₂ (%) | 98 |
| Respiratory rate | 14 |
| Temperature (°C) | 36.7 |
| Systolic BP (mmHg) | 132 |
| Diastolic BP (mmHg) | 78 |
The pulse is irregular at rest. Examination is otherwise normal. Potassium, magnesium and thyroid function are normal, and an echocardiogram shows a structurally normal heart.
An ECG is performed
Questions
What does this tracing show?
Which feature separates the pauses here from second-degree atrioventricular block?
Follow up and review
Your patient is started on the beta-blocker bisoprolol 2.5 mg daily and reviewed six weeks later. She reports the palpitations are much less frequent. Her pulse is regular at 78.
This ECG tracing is recorded at that visit.
Questions
What has changed between the two tracings?
Her pulse is faster at review than before the beta blocker was started. Why?
Diagnosis and Summary
Frequent atrial ectopy with non-conducted atrial ectopic beats, suppressed by beta blockade
Premature atrial and ventricular complexes frequently lead to beats that aren’t palpable or heard on auscultation. This effect can be even more pronounced when PACs are non-conducted.
Here, beta blockers can paradoxically lead to higher pulse due to suppressed automaticity and regularisation of the rhythm.
References
TOP 150 ECG Series
David Yu, M.D., Ph.D. Full time anesthesiologist in the department of Perioperative medicine and Intensive Care (PMI), Karolinska University Hospital, Sweden. Dual board certified in internal medicine, and anesthesiology and critical care. Clinical interests are the critically ill patient, hemodynamic cases, perioperative echocardiography and procedural awareness, and of course all things ECG! | Squiggler |