The "low intensity treadmill exercise" protocol for appropriate rate adaptive programming of minute ventilation...

Area of Science:

• Cardiology
• Exercise Physiology

Background:

• Rate adaptive pacemakers aim to mimic physiological heart rate responses during exercise.
• Minute ventilation (MV) measured by transthoracic impedance is a key parameter for pacemaker rate control.
• Accurate programming of pacemaker response requires understanding the heart rate to minute ventilation (HR/VE) relationship.

Purpose of the Study:

• To determine the physiological HR/VE relationship during peak exercise.
• To develop a database for programming minute ventilation-controlled pacemakers.
• To evaluate if a low-intensity exercise test (LITE) can substitute for peak exercise tests (RITE) in assessing the HR/VE slope below the anaerobic threshold.

Main Methods:

• 41 healthy subjects underwent treadmill exercise testing (RITE and LITE protocols).
• Breath-by-breath gas exchange was collected.
• Linear regression analysis determined HR/VE slopes below and above the anaerobic threshold and during LITE.

Main Results:

• The HR/VE relationship during RITE was curvilinear, not linear.
• The HR/VE slope was steeper below the anaerobic threshold (1.54 ± 0.51) than above (1.15 ± 0.37).
• The HR/VE slope during LITE (1.58 ± 0.88) did not differ significantly from the RITE slope below the anaerobic threshold (P = 0.79).

Conclusions:

• Rate adaptive pacing should simulate the curvilinear HR/VE relationship from rest to peak exercise.
• The LITE protocol effectively substitutes for peak exercise tests in determining the HR/VE slope below the anaerobic threshold.
• LITE enables accurate pacemaker programming for physiological rate response matching patient effort.