Minute Ventilation Parameter Tuning

There is a serious misconception among many electrophysiologists that minute ventilation pacemakers are no more effective than accelerometer-only pacemakers for people who need constant or almost constant pacing and that tuning pacemakers is a waste of time.Nothing can be further from the truth, whether you are sedentary or active.

When implanted, the Inliven pacemaker is set up with default values and hence needs to be tuned for any particular patient's needs at a pacing clinic by a company technician or a qualified electrophysiology technician.

I am paced 100% of the time and totally dependent on the pacemaker for my cardiac response to physical and emotional stress. From previous experiments with my accelerometer-only pacemaker, I knew that my optimal heart rate on a treadmill placed at a 12% incline and moving at 1.5 miles an hour is 130-135 BPM. So when I showed up at a clinic to tune
my new Inliven pacemaker, I requested that we set up a treadmill as above and that they adjust the pacemaker parameters to make my heart rate 130-135 BPM while I was on the treadmill. Unfortunately that did not go well and the resulting pacemaker parameter values were very ``aggressive.'' In retrospect, this must have happened because I did not spend enough time on the treadmill. The result was that the first time I climbed a set of stairs, my heart rate went up to 170 BPM, which felt quite uncomfortable.
That evening, I spent a lot of time reading the relevant sections
of the Inliven Clinician's Manual and searching the net trying to
understand how the ``minute ventilation'' part of the device works andhow one could optimize its settings in a individual. I wrote up my findings and the very positive effect they produced on my wellbeing on my website
http://www.eecs.berkeley.edu/~polak/inliven
for anybody else who might be interested.

5 Comments

Thank you

by Rochelle - 2015-10-21 04:10:10

Thank you all for your knowledge. I had a question about something you said, but found my answer. Thanks!

Rate response

by golden_snitch - 2015-10-21 04:10:47

Motion sensors (accelerometers) react fast, but usually do not respond well to activities that do not include upper body movement, like cycling, swimming etc. Minute ventilation sensors respond whenever you breath faster or harder, but they respond very slowly. Minute ventilation and accelerometer combined kind of make up for each other's limitations. The response you get from both combined is, according to my experience, quite good. But these two sensor do not respond to mental stress at all.

Closed-loop stimulation (CLS) is a sensor that is based on measuring cardiac contractility (don't ask me how exactly). It does not need upper body movement or increased minute ventilation rates to sense activity. By measuring contractility it can also respond to situations when you, for instance, are nervous, stressed or fearful. CLS increases my heart rate when I have a nightmare or when I watch a scary movie or have a job interview where I'm very nervous - just like a normal heart would do.

But CLS has problems, too. All available sensors have. You always need to compromise. There is no sensor out there that is as good as a working sinus node.

@ golden_snitch

by Rochelle - 2015-10-21 04:10:49

Thank you. That's exactly what I wanted to know. I appreciate how you explained it.

RR

by golden_snitch - 2015-10-21 05:10:01

There is no minute ventilation only pacemaker. Those that feature a minute ventilation sensor all also have an accelerometer (Sorin Group, Boston Scientific). You get the best results when you switch both on and combine them. Pacemakers that feature two sensors are not intended to work with one only; one only provides a worse rate response than both together. It is possible to activate only one, but that's not the purpose in devices with two sensors.

I have tested all rate response sensors that are available in the past 16 years, had three different pacemaker models from three different manufacturers so far. The minute ventilation + accelerometer combination is a good one, definitely much better than one of these sensors alone. I now have a CLS sensor, which is also not that bad, but has, as all sensors, some problems. But it does respond to most activities and also to mental stress.

accelerometers

by lucienp84 - 2015-10-29 01:10:21

Accelerometers benefit the young because they move relatively fast and the sensitivity of the accelerometer can be set to medium. For the elderly, to be of any use, the sensitivitiy has to be turned up high, but then the negative effects, such as vibrations of busses and pickup trucks and the extra acceleration walking down hills and steps, become quite pronounced and result in unpleasant and unnecessary considerable increases in heart rate. The elderly do not need quick starts and hence are best off with the accelerometers turned off.

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