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Ventilation and Heart Rate Response During Exercise in Normals: Relevance for Rate Variable Pacing
Author(s) -
TREESE NORBERT,
MacCARTER DEAN,
AKBULUT OMAR,
COUTINHO MARIO,
BAEZ MARCHENA,
LIEBRICH ANDREAS,
MEYER JÜRGEN
Publication year - 1993
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1993.tb01040.x
Subject(s) - medicine , heart rate , anaerobic exercise , ventilation (architecture) , cardiology , respiratory minute volume , work rate , vo2 max , respiratory rate , respiratory system , linear regression , anesthesia , physical therapy , blood pressure , mathematics , mechanical engineering , engineering , statistics
The observation of a close relationship of heart rate to oxygen uptake (HH‐VO 2 ) and heart rate to minute ventilation (HR‐VE)has been shown to be of particular value in rate variable pacing. However, the impact of anaerobic threshold (AT)for the HH‐VO 2 and HH‐VE slope has been studied Jess. Twenty‐three male and 16 female subjects, mean age 52 ± 7 years, were selected in whom complete heart catherization and extensive noninvasive sludies excluded major cardiopulmonary disease. Semisupine bicycle exercise testing with analysis of respiratory gas exchange was performed using a ramping work rate protocol with work increments of 20 watts/min. At the respiratory AT, determined by the V slope method, oxygen uptake (VO 2 ‐AT)was 15.2 ± 3.0 mL/kg in males versus 13.8 ± 2.3 mL/kg in females and heart rate (HR‐AT)was 109 ± 18 beats/min versus 119 ± 20 beats/min, respectively. Heart rate was highly correlated (r ±0.9)to VO 2 and minute ventilation (VE). A linear regression for HR‐VO 2 , however, was found only in 16/39 and for HR‐VE in 11/39 subjects. Assuming the AT as the breakpoint of two linear curves, it could be demonstrated that compared to low exercise HR appeared to increase at maximal exercise more in relation to VO 2 but less in relation to VE; in men the individual slopes for HR‐VO 2 were 2.6 ± 0.7 below but 3.2 ± 1.0 above AT (P < 0.05) and the slopes for HH‐VE were 1.6 ± 0.5 below but 1.0 ± 0,4 above AT (P < 0.05). Similarly, in women the individual slopes for HR‐VO 2 were 3.7 ± 1.4 below but 4.3 ± 1.4 above AT (P < 0.05)and the slopes for HR‐VE were 2.1 ± 0.9 below but 1.3 ± 0.4 above AT (P < 0.05). The differences between male and female subjects were significant. The nonlinear behavior of the HB‐VO 2 and HR‐VE relation from rest to maximal exercise should have a particular impact in respiratory controlied pacing systems.