Pacemaker Behavior’s Behavior s Prof Glikson, Sandra Schor-Wider Nadav Hayman

Patient Case Description • This is a patient with SSS + PAF with a DDDR pacemaker . He did not tolerate MVP in the past so we turned it off. • He recently complains of palpitations of two types : • Sudden events of rate around115 • Rate about 80 , general weakness that reminds him of the sense of temporary VVI pacing during clinic visits • He was able to record both episodes • We programmed the AHR diagnostics to detect relatively slow tachycardias which were indeed recorded .

Pacemaker setup

•RAAVD – OFF •SEARCH AV – OFF •MS- OFF •ACM & VCM – ON •SINUS PEREFERENCE –ON SINUS ON

Patient Holter strip – Baseline Rhythm

Tachycardia (the faster type ) in Holter strip

Sudden termination of the tachycardia

Episodes of AHR From the Pacemaker Memory

Continued 

Episodes of AHR From the Pacemaker Memory – the “faster “ type

Another AHR Episode From The Pacemaker – the “slower” type

Questions
• What do you think of the strips ? • Is there any “strange behavior” of the pacemaker ? strange behavior • What are the two Different diagnosis for the two strips ? • Th h ld , sensing and i Thresholds i d impedances are all within normal d ll ithi l ranges

Think and ….

Answer to The first rhythm – is it PMT?
1 2 3 4 5 6 7 8

VA conduction test performed in clinic by pacing V

VA during testing is indeed very similar to VA in tachycardia: PMT most likely explanation

OK so it is PMT what happened after 8 b t ? i h th d ft beats
PMT termination algorithm attempted to terminate the tachycardia
1 2 3 4 5 6 7 8

PVARP EXTENSION TO 400MS

Why didn’t it terminate the tachycardia ?

NCAP Interval of I t l f 300ms Atrial pacing without capture due To atrial refractoriness resulting in Triggerring of PMT again

Ongoing PMT

Now that we believe that this is PMT why did it start?
1 2 3 4 5 6 7 8

What is unusual here ? Why is it pacing at 100 bpm with AV delay = 380 ? Why does this rhythm trigger PMT?

Why are the AV Delays prior to tach lengthening?

ACM
Overview • Runs only in MVP, DDD, or DDDR modes • No anticipated lead restrictions • Scheduling the search
– “Day at 1:00 AM” is nominal – “Day at Rest” value allows pacing system to determine best time of day to run the test successfully

Programmable “Test Frequency/Test Time” may allow physicians to titrate therapy during medication changes and p g periods of p potential threshold instability. “Acute Phase OFF” allows daily measurements to begin immediately and output to be adapted immediately, adapted, following successful measurements in patients with chronic leads.

ACM vs. VCM
Overview

It’s not at all like VCM • ACM does NOT look for “Evoked Response Evoked Response”
– Evoked response P-wave is small, prone to under-sensing

• ACM runs in patients with either:
– Periods of sinus rhythm (AS’s), or – P i d of AV conduction (AP VS’ ) Periods f d ti (AP-VS’s)

• ACM does not have an in-office test

ACM
Details

ACM Ob Observes the Timing of Sensed P- and th Ti i fS dP d R-Waves to Evaluate Capture • Using the intrinsic sensing and pacing characteristics of the device, determine capture using one of the following two algorithmic methods:
– Atrial Chamber Reset (ACR) – AV Conduction (AVC)

• Method is selected automatically by the device at the time of test execution, after performing the following checks:
– Device operation check – Feature interaction check – Rhythm stability check

ACM
Details

Method Selection – “Stability Check” Asks/Answers the Question: Are Conditions Favorable Within the Patient’s Rhythm to C Conduct Atrial Threshold Measurements? ?
• Atrial Chamber Reset (ACR) method runs during stable sinus rhythm – If 8 consecutive AS events are sensed and rate < 87 bpm  ACR method is chosen • AV Conduction (AVC) method runs when stable intrinsic 1:1 AV conduction is observed with atrial pacing – If all VS events are observed and the max AP-VS interval is < 296 ms  AVC method is chosen • If rhythm conditions above are f h th diti b favorable f b th  ACR bl for both

MGP4

AVC
Details

• If AP-VS interval > 296 ms, device conducts one test cycle (2 of 3 test paces must conduct and capture) using PAV = 383 ms
– If VS conducts at the max interval, and the VS event occurs during the capture expected “window ” device runs threshold window, test using this offset – If no VS, test aborts; stability check will occur 30 minutes later

• First test sequence measures using the permanently p g programmed outputs to ensure that VS events are p conducted, and occurring during the “windows” expected for captured test pace • AVC method can only be chosen to run every 8 hours

22 ‫שקופית‬ MGP4 What is the rate of pacing during ACM ? Does it correspond with the rate that we observed ?
Michael Glikson Prof., 06/02/2011

MGP5

device conducts one test cycle (2 of 3 test paces must conduct and capture) using PAV = 383 ms

•First test sequence measures using the permanently programmed outputs to ensure that VS events are conducted, and occurring during the “windows” expected for captured test pace

23 ‫שקופית‬ MGP5 You did not mention that the beat that triggers the tach is probably the one with first noncapture due to test
Michael Glikson Prof., 06/02/2011

Scheduling the search g
“Day at 1:00 AM” is nominal “Day at Rest” value allows pacing system to determine best time of day to run the test successfully

AVC method can only be chosen to run every 8 hours hours…. Look at the time of the episode …

Conclusion
• Atrial capture management resulted in pacing with long AV delay and eventual loss of capture in the atrium • As soon as capture is lost in A, the following VP is followed by retrograde conduction to A that triggers PMT

What about the other rhythm that is around 80 bpm and is very symptomatic ?

Lets see what the pacemaker point of view… next slide

Pacemaker repetitive non-reentrant ventriculoatrial synchronous (RNVAS ) rhythm

Sinus or APB

AR = retro P
(VA Conduction)

Atrial noncapture Due to referactoriness f

PACEMAKER RNVAS

By the way – what is RNVAS ?
• RNVAS = repetitive nonreentrant ventriculoatrial synchronous rhythm • RNVAS results from a situation of retrogtrade P sensed in PVARP (AR) that is followed shortly thereafter by pacing in A that does not capture the atrium because it has just been captured by the AR • This atrial noncapture sets the stage for another retrograde P in PVARP , another noncapture of AP and so on again and again • The pa e feels like pace a e sy d o e as a Ps a e retrograde e patient ee s e pacemaker syndrome all s are e og ade • This phenomenon occurs more frequently in patients with SSS paced with relatively long AV delay

Summary of phenomena observed
• This case demonstrates :
– Intermittent pacing with long AV delay + Loss of atrial capture due to p g g y p atrial capture management – Loss of atrial capture during ACM immediately results in triggering of PMT when retrograde P falls out of PVARP h t d f ll t f – PMT termination is successful but PMT recurs almost immediately or is replaced by RNVAS – Loss of atrial capture results in RNVAS rhythm when retrograde P falls within PVARP (AR) and the immediately following P can not capture the refractory atrium

Solution
• We programmed ACM to OFF . • Since then the patient has no complains. • Additional Recommendation : • fi d PVARP th t i ~50ms l fixed that is 50 longer th retrograde conduction than t d d ti time or change minimum PVARP under Auto PVARP to ~50 ms longer than retrograde conduction time. • Sinus preference – OFF (hoping to pace the atrium most of the time and avoiding APB’s) APB s)

Pacemaker behaviors lays in the