Presentation Reduced Quantitative Pulmonary Blood Flow and its Relationship to Endothelial Dysfunction using O-15-Labeled Water PET in Chronic

Yoshinaga, Keiichiro  ,  Shimizu, Kaoruko  ,  Katoh, Chietsugu  ,  Tomiyama, Yuuki  ,  Ohira, Hiroshi  ,  Fujii, Satoshi  ,  Manabe, Osamu  ,  Tsujino, Ichizo  ,  Nishimura, Masaharu

OBJECTIVES: Elevated pulmonary arterial pressure (PAP) induces shear stress in the pulmonary artery, increasing vascular remodeling. It may affect lung perfusion in pulmonary hypertension (PH). Quantitative pulmonary blood flow (PBF) evaluation, unstudied in chronic thromboembolic pulmonary hypertension (CTEPH) and its pathophysiological effects on PBF, may improve sensitive pulmonary perfusion abnormality assessment. . Using O-15-labeled water PET, we sought to evaluate differences in lung perfusion between the two subgroups with PH and PBF’s relationship to endogenous NOS inhibitors such as asymmetrical dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), markers of endothelial dysfunction.METHODS: Nine CTEPH and 15 pulmonary arterial hypertension (PAH) with WHO functional class II or III PH underwent dynamic O-15-labeled-water PET to measure unilateral pulmonary perfusion. Using a single-tissue compartment model, we estimated PBF. Without left ventricle overlapping, we used right PBF for analysis. ADMA and SDMA were measured by HPLC. RESULTS: CTEPH and PAH showed similar mean PAP (mPAP) (CTEPH 37.912.4 vs. PAH 43.414.2 mmHg, P=0.30). CTEPH patients showed lower PBF than did PAH patients (129.023.7 vs.164.632.9 mL/100mL of lung/min, P=0.02). PBF negatively correlated with ADMA (R=-0.51, P=0.02) and trend to SDMA (R=-0.42, P=0.06).CONCLUSIONS: CTEPH had lower right PBF than did PAH even with similar mPAP. Reduced PBF estimated by O-15-labeled-water PET negatively correlated with ADMA in PH. Quantitative PBF measurements may reflect pulmonary endothelial damage in PH.

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