Cardiopulmonary, biomarkers, and vascular responses to acute hypoxia following cardiac transplantation

Previous studies have suggested good adaptation of cardiac transplant ( CT x) recipients to exposure to a high altitude. No studies have investigated the cardiopulmonary and biomarker responses to acute hypoxic challenges following CT x. Thirty‐six CT x recipients and 17 age‐matched healthy controls ( HC ) were recruited. Sixteen (16) patients (42%) had cardiac allograft vasculopathy ( CAV ). Cardiopulmonary responses to maximal and submaximal exercise at 21% O 2 , 20‐minutes hypoxia (11.5% O 2 ), and following a 10‐minute exposure to 11.5% O 2 using 30% of peak power output were completed. Vascular endothelial growth factor ( VEGF ), interleukin‐6 ( IL ‐6), suppression of tumorigenicity 2 ( ST 2) were measured at baseline and at peak stress. Endothelial peripheral function was assessed using near‐infrared spectroscopy. Compared with HC , CT x presented a lesser O 2 desaturation both at rest (−19.4 ± 6.8 [ CT x] vs −24.2 ± 6.0% O 2 [ HC ], P  < 0.05) and following exercise (−23.2 ± 4.9 [ CT x] vs −26.2 ± 4.7% O 2 [ HC ], P  < 0.05). CT x patients exhibited a significant decrease in peak oxygen uptake. IL ‐6 and VEGF levels were significantly higher in CT x recipients in basal conditions but did not change in response to acute stress. CT x patients exhibit a favorable ventilatory and overall response to hypoxic stress. These data provide further insights on the good adaptability of CT x to exposure to high altitude.