Upper Rate Behavior

Why do we have Upper Rate Responses? Reduce incidence of tracking inappropriate rhythm and/or rate

Upper Rate Response Initiating Factors Exercise Sinus Tachycardia Atrial Arrhythmia Sensing of Myopotentials VA conduction exceeding PVARP

Upper Rate Response Limit Fastest Atrial rate at which consecutively paced ventricular complexes maintain 1:1 synchrony Also known as: Ventricular Maximum Rate (VMR) Maximum Tracking Rate (MTR)

Max Track Rate / Max Sensor Rate Definitions The Max Track Rate, or Maximum Tracking Rate, is the fastest rate that intrinsic P-waves can be tracked, or followed by paced Ventricular events with a 1:1 ratio. The Max Sensor Rate, is the fastest rate the atria and the Ventricles can be paced, based upon sensor input.

DDD Timing A A VI VI PV PVARP Atrial Channel PVAB BL VRP Ventricular Channel URI

Max Track Rate The fastest rate the Ventricular channel can pace when tracking intrinsic P-waves.

Max Track Rate Programmed settings should be based on Patient activity levels Age (220 – age) LV function Chest pain Tolerance by the Patient if a PMT occurs

Max Track Rate Questions to consider Can the programmed Max Track Rate be tolerated by the patient for prolonged periods? During sinus tachycardia, can a sudden drop in the pacing rate be tolerated?

Upper Rate Behaviors Fixed-Ratio block/Multiblock (2:1, 3:1, etc) Wenckebach behavior (Pseudo, Electronic) Auto Mode Switch (not in this presentation)

Upper Rate Behaviors Depends on programmed values: Max Tracking Rate Sensed AV Delay PVARP

Upper Rate Behavior Fixed Ratio Block

Fixed-Ratio Block (Multiblock) Fast Upper Rate Response Simplest way to control upper rate TARP = MTR AV PVARP TARP (Total Atrial Refractory Period)

2:1 Block (one v-paced event per two p-waves) Fixed-Ratio Block 2:1 Block (one v-paced event per two p-waves) MTR = 115bpm AVD = 160ms PVARP = 360 ms

Fixed-Ratio Block Calculation 60,000 / TARP: e.g. 60,000 / 440 ms = 136 BPM (2:1 block point) PV PVARP 160 ms + 280 ms TARP = 440 ms

Fixed-Ratio Block PV interval always remains constant May be inappropriate in young or physically active patients due to sudden rate drops Patient tracks P-waves until the atrial rate gets to the 2:1 block The Ventricular rate will suddenly go to half the Atrial rate

Fixed-Ratio Block Fall Down Rate

2:1 blocking Ex.: Shipped Settings PV Delay 150 ms PVARP 275 ms Atrial rate Stimulated ventricular rate Ex.: Shipped Settings PV Delay 150 ms PVARP 275 ms 2:1-blockpoint 142 min-1 160 140 120 100 In shipped settings, the 2:1 block rate is quite low! This would affect pacing in normal, physiologic rate range of many patients and has to be dealt with. 80 60 Sensed Atrial Rate 80 100 120 140 160

Upper Rate Responses Wenckebach

Upper Rate Behavior Wenckebach block

Do you remember? AV Block 2nd degree Mobitz I

Wenckebach Max Track (MTR) must be programmed slower than the TARP interval 2:1 fixed-ratio block will occur when the P-P intervals become faster than TARP

Wenckebach Base Rate Interval AV AV PV V-A Interval PVARP MTR TARP Ap Vp P P P Base Rate Interval AV AV PV V-A Interval PVARP MTR TARP W-Period

Wenckebach behaviour Look at the VV and AV intervals

Wenckebach Provides a smoother transition from 1:1 to 2:1 block Avoids a sudden reduction of the ventricular pacing rate and maintains some degree of AV synchrony

Wenckebach response to increasing Atrial rates Plateau 3:1 Ventricular Rate (paced) 1:1 2:1 . . . . . . . Lower Rate MTR TARP ARRP Atrial Rate (sensed)

Wenckebach Example DDD MTR 100 bpm (600 ms) AV delay 150 ms PVARP 250 ms TARP 150 + 250 = 400 ms \150ppm Therefore, atrial rates >100 bpm (600 ms) but < 150 bpm will result in Wenckebach behavior Max PV delay prolongation is 200 ms (600-400) PV intervals will vary from 150 - 350 ms

Wenckebach Calculation to determine if a Wenckebach is present: Programmed MTR minus TARP In our example: 600 ms - 400 ms = 200 ms We have a 200 ms Wenckebach window

Atrial Rate Continuum Base Rate 60 PPM MTR 130 PPM AV delay 170 MS PVARP 250 MS 60 PPM 130 PPM 143 PPM Base Rate (MTR) TARP Device Response 1:1 Tracking Wenckebach 2:1 Block TARP = PV Delay + PVARP = 170 + 250 = 420 ms 143 PPM (2:1 Block Point)

Wenckebach 150 ms 600 ms 200 ms Base Rate Interval AV AV PV Ap Vp P P P Base Rate Interval AV AV PV 150 ms V-A Interval PVARP 600 ms MTR TARP 200 ms W-Period

Pseudo Wenckebach - Upper Rate Behaviour A-A AV Delay PVARP VRP MTRI Maximum Tracking Rate Interval

Wenckebach Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms Min. PV 88 ms PVARP 250 ms

Wenckebach P-wave in alert and sensed PVARP MTR Ventricular pacing at Max Tracking Rate Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms Min. PV 88 ms PVARP 250 ms

Wenckebach Identification Variable PV delays Sustained high rate pacing Occasional change in the beat to beat ventricular rate Long PV intervals may initiate an endless-loop Tachycardia

Wenckebach and MTR Atrial rate 160 140 120 100 80 60 80 100 120 140 Stimulated ventricular rate 160 140 TARP 120 = Max. Tracking Rate 100 Theoretically, you could limit the fall at 2:1 block by use of MTR. This method may be used in systems without rate modulation, but is, of course, seldom the optimal method. 80 60 Sensed Atrial Rate 80 100 120 140 160

Upper Rate Responses Fixed-ratio Block Wenckebach AMS AV Delay constant until DDI(R) pacing occurs at the AMS base rate PV Delay constant AV Delay progressively lengthens Pauses in pacing operation may be seen

2:1 blocking Ex.: Shipped Settings PV Delay 150 ms PVARP 275 ms Atrial rate Stimulated ventricular rate 160 Ex.: Shipped Settings PV Delay 150 ms PVARP 275 ms 2:1-blockpoint 142 min-1 140 120 100 In shipped settings, the 2:1 block rate is quite low! This would affect pacing in normal, physiologic rate range of many patients and has to be dealt with. 80 60 Sensed Atrial Rate 80 100 120 140 160

Factors Limiting Upper Rate V TARP equals PV delay plus PVARP. This is the limiting factor when P-wave tracking. PV Delay PVARP Programmed PV Delay Rate Resp. AV/PV Delay Shortest AV/PV Delay Programmed PVARP Rate Resp. PVARP/VRP Shortest PVARP/VRP

Rate Responsive AV Delay To mimic normal heart function 70 min-1 110 min-1 130 min-1 Spontaneous PR interval reduction Tracking with RRAVD enabled Rate responsive AV delay will increase the 2:1 block rate. It can be physiologic on exercise. RRAVD is mainly intended for AV block patients.

Rate Responsive AV/PV Delays and Shortest AV/PV Delay 200 150 100 50 90 95 100 110 105 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

Rate Responsive AV/PV Delays… … and Shortest AV/PV Delay 200 150 100 50 90 95 100 110 105 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

2:1 blocking and RRAVD Ex.: Shipped Settings PV Delay 150 ms Atrial rate 2:1 blocking and RRAVD Stimulated ventricular rate 160 Ex.: Shipped Settings PV Delay 150 ms PVARP 275 ms With RRAVD (Low, Medium and High) 140 120 100 80 60 Sensed Atrial Rate 80 100 120 140 160

Rate Responsive Refractory Periods PVARP Rate responsive refractory periods is another way of managing the 2:1 block point. This feature is intended mainly for patients with sinus node disease. This is because RRAVD would promote ventricular stimulation at higher rates, something you do not want in case of no AV block. VRP Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

Rate Responsive Refractory Periods PVARP VRP Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

Rate Responsive Refractory Periods PVARP VRP Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

Rate Responsive Refractory Periods PVARP VRP Low, 1 ms min-1 Medium, 2 ms min-1 High, 3 ms min-1

Pseudo Wenckebach Upper Rate Behaviour Maximum tracking rate will limit the paced ventricular rate on tracking by producing a blocking similar to Wenckebach block. MTR Intervall MTR Intervall MTR Intervall MTR Intervall

2:1 blocking and MTR Atrial rate Stimulated ventricular rate 160 140 = Max. Tracking Rate Programmed MTR, too high. Will not limit the rate fall at 2:1 block rate. 120 100 In a DDDO system, programming MTR as high as possible will not limit the stimulated ventricular rate fall significantly. If 2:1 block rate is within the physiologic rate range of the patient, this is not a good programming. 80 60 Sensed Atrial Rate 80 100 120 140 160

2:1 blocking Use of a well tailored Atrial rate Stimulated ventricular rate 160 140 = Max. Tracking Rate = Max. Sensor Rate 120 = Sensor Indicated Rate Use of a well tailored sensor will relieve the problems of a high MTR 100 It is ok to programme high MTR if the sensor is ON and programmed slightly conservatively compared to the sinus node. Sensor Prediction Model is the perfect tool for this. 80 60 Sensed Atrial Rate 80 100 120 140 160

Summary One to One tracking is the best upper rate behavior When tracking at this rate is inappropriate, the device may be programmed to exhibit: Fixed Ratio Block (Multiblock) Wenckebach RR AV delay – PVARP/VRP DDIR Auto Mode Switch

2/1 block (mentioned on Merlin) Summary When programming AV delay PVARP Max Tracking Rate Remember Wenckebach AVD + PVARP < MTR 2/1 block (mentioned on Merlin) AVD + PVARP = MTR

Merlin

Upper Rate Behavior Questions