Dual chamber modes
DDD
paces in atrium and ventricle
senses in atrium and ventricle
atrial sensing inhibits atrial pacing & triggers an AV delay
ventricular sensing inhibits atrial and ventricular pacing
Lower rate interval (LRI) – consists of 2 parts
•AV interval (ventricular escape period (VEP))
•Atrial refractory period (ARP)= timing of AV interval (ignores all AS signals)
•AV interval (SAV & PAV)
•Ventricular blanking periods (VBP) occurs only after an atrialy paced beat (prevents cross talk
•VA interval (atrial escape period (AEP))
•Ventricular refractory period (VRP) = ignores all VS
•Post ventricular atrial refractory period (PVARP) = ignores atrial signals following ventricular paced or sensed beats
Indications
•AV conduction disorders with normal or abnormal SN function
•SSS where Vp may be required
Contraindications
•Persistent AF/Afl
•Silent atria
DDI
paces in atrium and ventricle
senses in atrium and ventricle
atrial sensing inhibits atrial pacing (no AV delay triggered)
ventricular sensing inhibits atrial and ventricular pacing
Lower rate interval (LRI) – consists of 2 parts
•PAV interval (ventricular escape period (VEP))
•Atrial refractory period= timing of AV interval (ignores all AS signals)
•AV interval (PAV only)
•Ventricular blanking periods (VBP) occurs only after an atrialy paced beat (prevents cross talk
•VA interval (atrial escape period (AEP))
•Ventricular refractory period (VRP) = ignores all VS
•Post ventricular atrial refractory period (PVARP) = ignores atrial signals following ventricular paced or sensed beats
Indications
•AV conduction disorders with normal or abnormal SN function
•Paroxysmal/persistent atrial arrhythmia
•Atrial lead noise
Contraindications
•High grade AV block with normal sinus function
•Silent atria
•Chronic atrial arrhythmias
DVI
paces in atrium and ventricle
senses in ventricle only
ventricular sensing inhibits atrial and ventricular pacing
Lower rate interval (LRI) – consists of 2 parts
•PAV interval (ventricular escape interval)
•AV interval (PAV only)
•Ventricular blanking periods (VBP) occurs after an atrialy paced beat (prevents cross talk)
•VA interval (ventricular escape interval)
•Ventricular refractory period (VRP) = ignores all VS
Indications
•AV conduction disorders with normal or abnormal SN function
•When there is a reason for no atrial sensing (SSS, ?lead noise)
Contraindications
•Competitive atrial arrhythmias
•Silent atria
VDD
paces in ventricle only
senses in atrium and ventricle
atrial sensing triggers AV delay
ventricular sensing inhibits ventricular pacing
Lower rate interval (LRI) – consists of 2 parts
•SAV interval (ventricular escape interval)
•Atrial refractory period= timing of AV interval (ignores all AS signals)
•AV interval (SAV only)
No Ventricular blanking periods (VBP) occurs as no atrial pacing
•VA interval (ventricular escape interval)
•Ventricular refractory period (VRP) = ignores all VS
•Post ventricular atrial refractory period (PVARP) = ignores atrial signals following ventricular paced or sensed beats
Indications
•AV conduction disorders with normal SN function
•Chronic high atrial threshold with good sensing and normal sinus node function
Contraindications
•SND
•Silent atria
•Inadequate atrial sensing
•Chronic AF/AFl
DOO - asynchronous
paces in atrium and ventricle
no sensing
no sensing response
Lower rate interval (LRI) – consists of 2 parts
•AV interval
•VA interval
Indications
•Temporary use when external interference may interrupt pacing
Contraindications
•Competitive intrinsic rhythm
•Long term use
ODO
no pacing
sensing in atrium and ventricle
no sensing response
No pacing intervals
Indications
•Temporary setting when measuring sensing values
•If a device is required to be “turned off” (MRI setting/permanent pacing off)
Contraindications
•Pacing dependent
