The relationship between heart rate and oxygen consumption in heart transplant recipients during a cardiopulmonary exercise test: heart rate dynamic during exercise test.
BACKGROUND
In healthy subjects, the percentage of heart rate reserve (%HRR) versus the percentage of oxygen consumption reserve (%VO(2)R) is the closest relationship between heart rate and VO(2) and it seems also to be true to heart failure patients only if they are under optimized beta-blocker therapy.


OBJECTIVE
To evaluate the closest relationship between heart rate and VO(2) (%peak heart rate versus %peak VO(2); %HRR versus %VO(2)R or absolute heart rate versus absolute VO(2)) in heart transplant recipients during a treadmill cardiopulmonary exercise test.


METHODS
A total of 19 sedentary heart transplant recipients (5.4 ± 3.3 years after transplant) in a stable condition (for, at least, 3 months), were recruited to perform a cardiopulmonary exercise test. The relationship between %HRR-%VO(2)R, %peak heart rate versus %peak VO(2) and absolute heart rate versus absolute VO(2) were tested.


RESULTS
The strongest relationship was found between %HRR-%VO(2)R (r = 0.95, p<0.0001), followed by %peak heart rate versus %peak VO(2) (r = 0.91, p<0.0001) and absolute heart rate versus absolute VO(2) (r = 0.67, p<0.0001). The mean regression line did not coincide with the line of identity in any group (p<0.0001 for all groups).


CONCLUSIONS
The %HRR versus %VO(2)R showed the closest relationship followed by %peak heart rate versus %peak VO(2) and absolute heart rate versus absolute VO(2). Despite this, the perfect reliability of the heart rate versus VO(2) was not found.
Carvalho
Vitor Oliveira
VO
Bocchi
Edimar Alcides
EA
Pascoalino
Lucas Nóbilo
LN
Guimarães
Guilherme Veiga
GV
D000328:Adult; D005080:Exercise Test / Q000379:methods* / Q000592:standards; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D014180:Transplantation / Q000502:physiology