Erroneous diagnosis of bradycardia
Tracing
Manufacturer Medtronic
Device ILR
Field Reveal DX / Reveal XT
N° 8
Patient
A 66-year-old man underwent implantation of a Reveal XT for recurrent syncope without apparent precipitating cause. An ECG and echocardiogram were normal.
Graph and trace
An episode was recorded automatically and remotely transmitted.
- clear undersensing of the ventricular electrograms causing spurious diagnoses of bradycardia (B) and asystole (AD); some of the ventricular electrograms are accurately sensed (VS); on the graph, the longest R-R interval is 2000 ms long, which is the programmed bradycardia rate; should the R-R interval be longer, it will appear as 2000 ms on the graph and >2000 ms on the tracing.
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The automatic recording of episodes of bradycardia or tachycardia increases the diagnostic yield of the ILR. The asymptomatic and symptomatic episodes occurring in patients incapable of triggering the system are therefore memorized. However, an important limitation of this function is the frequent spurious recording of a) bradycardia due to undersensing of ventricular signals, or b) tachycardia due to the sensing of noise or other cardiac signals, such as P or T waves or double counting of the R wave. This implies a verification of all episodes stored in the device’s memory. Spurious arrhythmic episodes are recorded in >75% of ILR recipients.