Improvement of microcirculatory vessel density in the early post-operative period of heart valve surgery: an observational study

Abstract Introduction Cardiac surgery with cardiopulmonary bypass (CPB) is associated with microcirculatory perfusion disturbances that persist after the surgery and that can cause multiple organ dysfunction. Little is known about the effects of heart surgery on the microcirculation of patients in the postoperative period of heart valve surgery. Purpose The purpose of the study is to identify the alterations that occur in the sublingual microcirculation of patients submitted to heart valve surgery using cardiopulmonary bypass. Such findings may guide future implementation of routine microcirculation assessment in the postoperative period of cardiac surgery. Methods This was a single-center cross-sectional observational study that included thirty patients aged 52 ± 14 years and enrolled during a period of four months, scheduled for heart valve surgery with CPB at a quaternary public hospital. Sublingual microcirculatory density and perfusion were assessed using a handheld camera based on incident dark-field (IDF) imaging. Each recruited patient was evaluated in two stages: 1) during hospitalization, in the preoperative period of cardiac surgery to be performed within the next 48 hours; 2) in the early postoperative phase of cardiac surgery, within the first four hours of the patient's arrival at the intensive care unit. At least three videos of 5 seconds each were obtained in both stages. Images were analyzed using automated software as well as visual analysis. For analysis purposes, we considered vessels as capillaries if diameter ranges between 6.04-15.9 µm and non-capillaries if diameter ranges between 16-50 µm. Results We observed a statistically significant increase in the total number of vessels (TVN) after surgery (1076 ± 156) compared to values obtained before surgery (943 ± 117, P=0.0004). In addition, the total number of capillaries vessels (TNCV) was also greater after surgery (998 ± 132) compared to the preoperative period (877 ± 106; P=0.0001), the same being observed in the total length of capillaries vessels (TLCV) after surgery (28.7 ± 3.3 mm) compared to before surgery (25.8 ± 3.0 mm; P=0.0005) and capillary vessel density (CVD) (16.4 ± 1.9 and 14.8 ± 1.7 mm/mm2) after and before surgery, respectively (P=0.0005). With regard to non-capillary vessels, no difference was observed in total number of non-capillary vessels (TNNCV) after [68 (49-104)] and before surgery [69 (49-78)] (P=0.21), as well as in total length of non-capillary vessels (TLNCV) after [1.6 (1.2-2.4)] mm and before [1.5 (1.1-1.8.)] mm (P=0.25) surgery. Finally, non-capillary vessel density (NCVD) was also similar after [0.89 (0.67-1.36)] mm/mm2 and before surgery [0.83 (0.66-1.06)] mm/mm2 (P=0.34). Conclusion In patients undergoing heart valve surgery, there was a significant increase in postoperative microvessel number, mainly due to the increase in the density of capillaries vessels.