Right ventricular oxygen supply and diffusion in human and experimental pulmonary hypertension

Introduction: In pulmonary hypertension (PH), right ventricular (RV) oxygen supply has to increase to meet the higher oxygen consumption due to the high RV power output. To investigate how the RV adapts to meet these requirements, we studied the oxygen supply and intracellular diffusion in terms of capillarization and myoglobin content in patients with PH. In addition, we compared healthy rats to a rat model with stable PH (preserved cardiac output) and progressive PH (RV failure) to answer the question whether adaptations in oxygen handling are characteristic for the failing RV or develop during progression of the disease. Methods: RV tissue was collected at autopsy of 10 diseased PH patients and 10 control patients who died from a left ventricular myocardial infarction. In rats, stable PH and progressive PH were induced by monocrotaline 40 and 60 mg/kg, respectively. RV cardiomyocyte cell size, capillary density and myoglobin content were determined. Results: RV cardiomyocyte cell size is strongly increased in PH patients compared to controls (PH: 824±125 vs con: 353±97 μm 2 , p 2 , p Conclusion: Oxygen supply to and diffusion within the cardiomyocytes is reduced in both failing human and rat RV. This is characteristic for the failing PH RV since stable PH rats maintained supply and diffusion.