Bradycardia assessment
Bradycardia basics
Purpose
Rarely performed in the current times.
​
Previously performed for patients with unexplained syncope.
​
May be utilised if any suspicion of damage to sinus or AV node during an EP procedure.
Sinus node assessment
Equipment
1 venous sheath
​
Requires a minimum of 1 high right atrial catheter (JSN)
​
Sinus node recovery time (SNRT) procedure
-
Burst pacing at a set rate for 30 seconds is performed at different rates (600ms, 500ms and 400ms)
-
The PPI on the HRA catheter is measured immediately after pacing termination.
-
A normal SNRT response is <1600ms.
-
A corrected SNRT (cSNRT) can be calculated to account for differences in basic cycle length
-cSNRT = SNRT - BCL​
-a normal cSNRT is <525ms​​
Sinoatrial conduction time (SACT) procedure
-
Vary rarely used
-
An estimate of time needed from the sinus activation to the atrial tissue​
-
If prolonged suggests a degree of sinus exit block​
-
Can be measured with a burst of atrial pacing (Narula method) or with a single APB- sensed APB - S2 (Strauss method)
-
Strauss method: (S2-PPI) - ACL /2
-
Normal SACT <120ms
AV node assessment
Equipment
1 venous sheath
​
Requires a minimum of 1 JSN catheter to measure HIS region signals (AH, HV)
​
AV wenckebach thresholds can be checked and may be compared to pre ablation numbers if there is suspicion of damage to the AVN
​
Measurements
Normal AH interval: 55-140ms
Normal HV interval 35-60ms