Question 15.1
A 69-year-old male presents with a fractured neck of femur following a syncopal episode. He is now well and has an ECG (Figure 1 shown on page 14) prior to his surgical procedure.
a) What does the ECG show? (10% marks)
b) What complication is likely to have led to his fall, and how would you manage it? (20% marks)
College answer
a)
Tri-fascicular block
b)
• Cause – Complete heart block
• Management –
o Correct electrolyte and endocrine abnormalities (e.g. K+, thyroid function tests)
o Consider influence of drug therapies such as digoxin, calcium channel antagonists
o Investigate for ischaemic heart disease
o Referral to cardiology unit for further evaluation (?permanent pacemaker)
Discussion
That ECG has just enough movement artifact on it to look "genuine". It is in fact not the original college image (because lawyers, etc) but comes from the authors' own collection, from a patient with a right bundle branch block, LAFB and a PR interval so prolonged that the ECG machine misinterpreted it as AF. The patient also had a serum potassium of around 6.6 mmol/L, which was unhelpful.
Management of trifascicular block with syncope? The 2008 ACC/AHA/HRS guidelines and their 2012 focused update both recommend:
- Exclude drugs as the influence on AV conduction (eg. β-blockers)
- Exclude electrolyte disturbances
- Consider the prolonged PR interval as the herald of a complete heart block
- Consider the syncope a sign that intermittent complete heart block is occurring
- The presence of syncope and even mere bifascicular block upgrades the class for recommendation for PPM insertion from Class IIa to Class I ("Benefit >>> risk")
References
Epstein, Andrew E., et al. "ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons." Heart rhythm 5.6 (2008): e1-e62.
Epstein, Andrew E., et al. "2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities." Circulation 127.3 (2013): e283-e352.