Is ventilatory efficiency (VE/VCO(2) slope) associated with right ventricular oxidative metabolism in patients with congestive heart failure?
BACKGROUND
The relationship between minute ventilation and the rate of CO2 elimination (VE/VCO2 slope) is associated with mortality in patients with congestive heart failure (CHF). The VE/VCO2 slope > or =34 denotes a poor prognosis and has been proposed to reflect abnormalities in pulmonary perfusion.


OBJECTIVE
To study whether increased VE/VCO2 slope is associated with elevated right ventricular (RV) oxidative metabolism relative to the left ventricle (LV).


METHODS
21 patients with stable NYHA II-III CHF underwent symptom limited cardiopulmonary exercise testing. Dynamic [(11)C]acetate positron emission tomography (PET) was used to measure oxidative metabolism (k(mono)) of the LV and RV. Corrected RV oxidative metabolism (RVOx) was calculated as RV/LV k(mono) ratio.


RESULTS
Peak VO2 was 16.2+/-4.1 ml/min/kg and the VE/VCO2 slope was 33.4+/-6.1. LV and RV k(mono) were 0.046+/-0.009 and 0.037+/-0.007 min(-1), respectively, with a RVOx of 0.83+/-0.17. There was a good correlation between RVOx and the VE/VCO2 slope (r=0.61, p=0.0034). RVOx was 0.77+/-0.16 in patients with a VE/VCO2 slope <34 and 0.93+/-0.16 in patients with VE/VCO2 slope > or =34 (p=0.047).


CONCLUSIONS
RVOx correlates with VE/VCO2 slope in CHF patients. This supports the hypothesis that pulmonary vascular resistance is a determinant of the VE/VCO2 slope.
Ukkonen
Heikki
H
Department of Medicine, Turku University Hospital, Turku, Finland. heikki.ukkonen@tyks.fi
Burwash
Ian G
IG
Dafoe
William
W
de Kemp
Robert A
RA
Haddad
Haissam
H
Yoshinaga
Keiichiro
K
Davies
Ross A
RA
Gannon
Edward K
EK
Dasilva
Jean N
JN
Beanlands
Rob S B
RS
D018450:Disease Progression; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation / Q000502:physiology*; D013147:Spirometry; D015899:Tomography, Emission-Computed, Single-Photon; D016277:Ventricular Function, Left / Q000502:physiology*