Search AV + and risk of PMT

Tracing

N° 4

Manufacturer Boston Scientific Device PM Field AV delays, refractory periods management of tachycardia

Patient

Graph and trace

After 32 cycles, search for intrinsic activation with prolongation of the AV delay (Search AV +)
Premature atrial contraction followed by ventricular pacing after a long AV delay,
retrograde conduction and PMT
After 16 consecutive cycles VPMT-AS, prolongation of the PVARP and interruption of the PMT

Comments

During the search for intrinsic conduction (Search AV +), the 1:1 physiological atrioventricular activation is preserved (no dropped P wave)
There is an increased risk of pacemaker-mediated tachycardia (temporary prolongation of the AV delay)
In this patient, the association between retrograde conduction, premature atrial contraction and temporary prolongation of the AV delay is responsible for the PMT episodes recorded in the device memory
The risk of PMT is nil when the pacemaker is operating in AAI mode with VVI backup
The risk of PMT is very weak at the time of transition from ADI/VVI backup to DDD mode, the device systematically prolonging the PVARP on one cycle at the time of switch to DDD mode
The risk of PMT is greater during the search for intrinsic conduction (Search AV +), the temporary prolongation of the AV delay favoring the occurrence of retrograde conduction