Chest
Clinical InvestigationsCardiologyEffect of Hyperoxia on Left Ventricular Function and Filling Pressures in Patients With and Without Congestive Heart Failure
Section snippets
Study Population
Thirty-five patients, separated into three groups, participated in this study. The CHF group (n = 16; mean age, 62 ± 2 years; 15 men and 1 woman) all had stable symptoms (New York Heart Association class II and III) and a LV ejection fraction by radionuclide ventriculography of < 35% (mean value, 25 ± 2%). This group included 5 patients with idiopathic dilated cardiomyopathy and 11 patients with coronary artery disease. Medical therapy in this group included diuretics (n = 14), digoxin (n = 7),
Baseline Characteristics
The CHF group had significantly elevated heart rate and filling pressures, as well as impaired LV contractility and relaxation, compared to the normal LV function group. Baseline arterial O2 saturation was similar in the two groups (Table 1).
The Effect of Hyperoxia on Hemodynamics, Blood Gases, and Lactate Levels
In the CHF group, the hyperoxia stimulus was associated with several hemodynamic changes, including an increase in SVR, and reductions in cardiac output, stroke volume, and coronary sinus blood flow (p < 0.05 for all; Table 2). In the normal LV function
Discussion
Our study confirmed that hyperoxia causes systemic vasoconstriction and reduces cardiac output. We have expanded these findings by demonstrating that hyperoxia is also associated with prolongation in the time constant of isovolumic LV relaxation, τ, and increases in LVEDP. Therefore, our observations suggest that hyperoxia is associated with disturbances of both early and late phases of LV filling. Furthermore, these effects were observed not only in patients with CHF, but also in subjects with
Acknowledgment
The authors thank the staff of the Bayer Cardiovascular Clinical Research Laboratory of the Mount Sinai Hospital, as well as Drs. John Floras and John Parker for review of the article.
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Drs. Mak and Azevedo are Research Fellows of the Heart and Stroke Foundation, Dr. Liu holds the Heart and Stroke Polo Chair in Cardiovascular Research, and Dr. Newton is a Research Scholar of the Heart and Stroke Foundation of Canada.
This work was supported by a Grant in Aid from the Heart and Stroke Foundation of Ontario (grant No. NA-3469), and by Bayer Canada, Inc.