ECG of the Week - 4th February 2019 - Interpretation

The following ECG is from a 75 yr old male with a history of cardiomyopathy. He presented to the ED following shock delivery from his AICD. 

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ECG features:

• Initial ~3750ms of the ECG shows
• Wide complex tachycardia
• Rate 195-200 bpm
• No fusion or capture
• Variable noting in terminal QRS - ? atrial activity
• Initiation of anti-tachycardia pacing
• Series of 5 pacing spikes
• Reducing cycle length
• Capture with variable QRS morphology
• Cessation of wide complex tachycardia
• 800ms Pause
• 1 Native QRS complex
• Recurrence of wide complex tachycardia
• Same morphology as initial rhythm on ECG
• No fusion or capture
• Not typical BBB morphology

Interpretation:

• Wide complex tachycardia
• Monomorphic VT
• Termination by anti-tachycardia pacing (ATP)
• Recurrence of broad complex tachycardia

Anti-tachycardia Pacing (ATP)

This is a pacing mode found in AICDs which uses pacing delivery in an attempt to interrupt a re-entry circuit tachycardia. The advantage of ATP over shock delivery is that it prevents patient discomfort and prolonged battery life by minimizing need for shock delivery. ATP is ineffective for PMVT and VF; ATP delivery to monomorphic VT can result in acceleration and degeneration to PMVT or VF both of which will necessitate shock delivery to terminate.
Further information and some more examples can be found in the articles / posts below.

Case example from ECG Guru.com

• Anti-tachycardia Function of ICD

Articles

• Medtronic Academy
• Medscape Review (log-in required)
• Rosenqvist M. Antitachycardia Pacing: Which Patients and Which Methods? (Am J Cardiol 1996;78(supp5lA):92-97) - An older paper but covers some of the basics and freely available