Trying to understand my St Jude (ABBOTT) Assurity Pacemaker Model PM2240

I am trying to understand the terms, and how my pacemaker works as compared to Medtronics. There seems a lot of stuff online about Medtronic but not so much about St Jude. I am a 72 year old cyclist who has great difficulty getting my pulse up when I go up hills. I know that the pacemaker senses movement, which is minimal in cycling. From a previous post, it was mentioned that I should learn alot about my PM and have serious discussion with my EP about the parameters that PM has and how I would like them adjusted. I have downloaded the St Jude manual; and that is where my problem starts. The terms that St Jude uses are different than what I see posted about other PS's. I have a June appt. with EP and what to talk somewhat intelligently with the person. CAN YOU HELP with the following terms.

1.           Does the St Jude PM2240 have an automatic rate optimization? What is it called?

2.           What is it have a Rate Responsive AV Delay?

3.           What name is given to its accelerometer?

4.           What term is used for ADL rate?

5.           What term is used for an ADL Setpoint?

6.           On the PM2240 is the Threshold  the same as an Activity Threshold?

7.           What does the Hysteresis Rate do and how is it set?

8.           PM2240 uses a term “Reaction Time”.  What does it reacts to?

9.           Is the Max Sensor Rate the same as UR Setpoint  on a PM2240?

10.         What does the Max Tracking Rate actual track?

11.         What do Intervention Rate and Intervention Duration do?



Some pacemaker terms with understanding- I hope!

by Selwyn - 2020-05-04 13:13:18

1.No idea! My St Jude (Verity) adapts to day/sleep activity to conserve the battery. When I travel across time zones it takes some days to adapt.

2.AV intervals  can be changed , eg. shortened with increasing atrial rate for rate adaption

3. An accelerometer is the name ( this is used for the rate response function. ie. exercise coupled with movement.

4.The activities of daily living rate (ADL rate) is the approximate rate that the PM'd person must reach during moderate exercise (walking or household chores).

5.Perhaps the maximum excertion rate? There is also the upper sensor-driven rate limit reached during vigorous exercise.

6. Depends on which threshold you are talking about. A threshold is just that ie. a  limit . eg a rate limit, a sensing limit, a current limit etc.

7. Hysteresis enables the PM cycle to be given a longer time to obtain a natural heart beat, if possible. This helps maintain the synchronisation between the upper and lower heart chambers and increases battery life.

8. I would suggest you are talking about the onset of the rate response.

9. Sensing means just that, ie the ability to detect something. The upper rate limit is set manually.

10.Tracking is present when the ventricular paced rate follows the spontaneous atrial rate.

11.I think this refers to when the pacemaker is able to stimulate the heart muscle. The strength and duration of the delivered electricity must be sufficient to 'capture' the heart muscle and make it contract. The muscle will only contract once recovery has occurred- if the interval of electrical shocks is too close this will not happen and can be dangerous.



for a detailed understanding of rate response.

Trying to understand my St Jude (ABBOTT) Assurity Pacemaker Model PM2240

by DOG - 2020-05-04 20:53:04

Selwyn --- thanks for the detailed info. I am studying the stuff now. Glad someone else has a St Jude.

St Jude Assurity

by CyborgMike - 2020-05-09 03:10:34

I have a St Jude Assurity and I struggle with a similar issue. My natural HR won't go above 100 without the PM, so it is 100% pacing with exercise. For me, the sport is running. When I run fast downhill I am moving a lot and the PM will max out, but then I hit a steep hill, slow way down, so the HR drops, as the rate response accelerometer senses I am moving less, but I really need it to max out for me because it is going up a HILL. So uphill is a double whammy for me and I end up walking up. 

I've spent a lot of time tuning rate response with my EP, but there is nothing more to do. It is really the same with all PMs, since they aren't really smart. Someday, we'll be able to set our watch to workout running mode and have the PM know what we are doing, but for now all it has is an accelerometer, gyroscope, minute ventilation sensor and a really good algorithm. There just isn't an algorithm for going up hill. Just going fast or going slow. I really wish there was a manual override for exercise. Keep working with your EP to get it optimized for you. 

here is an old overview, but very simple explanation.

Cycling heart rate with St Jude

by DOG - 2020-05-09 11:37:02

CyborgMike the article seem excellent ... need to study iy well...Dog

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A properly implanted and adjusted pacemaker will not even be noticeable after you get over the surgery.