| Autor: |
Balmain, Bryce N, Tomlinson, Andrew R, Macnamara, James P, Sarma, Satyam, Hearon, Christopher M, Livingston, Sheryl A, Morris, Margot, Moran, Raksa B, Alcala, Jessica N, Payne, Marcus, Samels, Mitchel, Boyd, Teverick, Lee, David, Baird, Stephanie, Levine, Benjamin D, Babb, Tony G |
| Zdroj: |
Circulation (Ovid); November 2021, Vol. 144 Issue: Supplement 1 pA12146-A12146, 1p |
| Abstrakt: |
Introduction:Heart failure with preserved ejection fraction (HFpEF) patients exhibit a marked rise in PCWP during exercise, which may contribute to ventilation-perfusion (V/Q) mismatch and manifest as an increase in alveolar dead space (alveolar VD) and alveolar-arterial PO2difference (AaPO2). Nitrates reduce PCWP during exercise in HFpEF, but whether nitrates also reduce V/Q mismatch during exercise is unknown.Hypothesis:The increase in PCWP and V/Q mismatch during exercise would be attenuated with acute nitroglycerin (NTG) treatment compared with placebo in HFpEF patients.Methods:13 patients performed a 6min cycling test at 20W and an incremental cycling test (with right-heart and arterial catheterization) with placebo and NTG treatment. The physiologic dead space to tidal volume (VD/VT) was calculated using the Enghoff modification of the Bohr equation. Alveolar VDwas calculated as: VD/VTx VT- anatomic dead space (anatomic VD, estimated as 2mL/kg lean body mass). AaPO2was calculated using the alveolar gas equation. Data were analyzed using a 2-way ANOVA.Results:PCWP decreased with NTG at 20W (placebo: 21.1±6.2 vs. NTG: 16.5±6.1mmHg, p=0.02) and peak exercise (placebo: 33.7±7.1 vs. NTG: 26.2±5.6mmHg, p<0.01). However, alveolar VDdid not differ between treatments at rest (placebo: 0.11±0.07 vs. NTG:0.12±0.06L/breath, p=0.91), 20W (placebo: 0.22±0.09 vs. NTG: 0.24±0.10L/breath, p=0.62), or peak exercise (placebo: 0.34±0.14 vs. NTG:0.36±0.16L/breath, p=0.83). Nor did AaPO2differ between treatments at rest (placebo: 17.6±4.3 vs. NTG: 18.3±5.7mmHg, p=0.76), 20W (placebo: 22.0±6.9 vs. NTG: 22.1±8.1mmHg, p=0.99), or peak exercise (placebo: 25.1±9.1 vs. NTG: 27.8±9.9mmHg, p=0.41). No significant exercise-by-treatment interaction was detected for VD/VT(p=0.80).Conclusions:This study showed that NTG attenuated the increase in PCWP, but had no effect on the increase in alveolar VDor AaPO2during exercise. These findings suggest that the exercise-induced increase in V/Q mismatch may not be exclusively related to abnormal exercise hemodynamics. Further study is required to determine the clinical consequences and the mechanism(s) responsible for the progressive increase in V/Q mismatch during exercise in HFpEF patients. |
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