Contact-free optical assessment of changes in the chest wall perfusion after coronary artery bypass grafting by imaging photoplethysmography

Imaging photoplethysmography (iPPG) is a contact-free monitoring of the cutaneous blood volume pulse by RGB (red-green-blue) cameras. It detects vital parameters from skin areas and is associated to cutaneous perfusion. This study investigated the use of iPPG to quantify changes in cutaneous perfusion after major surgery. Patients undergoing coronary artery bypass grafting (CABG) were scanned before surgery and in three follow-up measurements. Using an industrial-grade RGB camera and usual indoor lighting, a contact-free imaging plethysmogram from the chest was obtained. Changes of the iPPG signal strength were evaluated in view of both the operation itself as well as the unilateral preparation of the internal thoracic artery (ITA) for coronary artery grafting, which is the main blood source of the chest wall. iPPG signal strength globally decreased after surgery and recovered partially during the follow up measurements. The ITA preparation led to a deeper decrease and an attenuated recovery of the iPPG signal strength compared to the other side of the chest wall. These results comply with the expected changes of cutaneous perfusion after CABG using an ITA graft. iPPG can be used to assess cutaneous perfusion and its global changes after major surgery as well as its local changes after specific surgical procedures

Treatment with XAV-939 prevents in vitro calcification of human valvular interstitial cells.

The development of a substance or inhibitor-based treatment strategy for the prevention of aortic valve stenosis is a challenge and a main focus of medical research in this area. One strategy may be to use the tankyrase inhibitor XAV-939, which leads to Axin stabilisation and subsequent destruction of the β-catenin complex and dephosphorylation of β-catenin. The dephosphorylated active form of β-catenin (non-phospho-β-catenin) then promotes nuclear transcription that leads to osteogenesis. The aims of the present study were to develop an experimental system for inducing in vitro calcification of human aortic valvular interstitial cells (VICs) to investigate the potential anti-calcific effect of XAV-939 and to analyse expression of the Wnt signalling proteins and Sox9, a chondrogenesis regulator, in this model. Calcification of human VIC cultures was induced by cultivation in an osteogenic medium and the effect of co-incubation with 1μM XAV-939 was monitored. Calcification was quantified when mineral deposits were visible in culture and was histologically verified by von Kossa or Alizarin red staining and by IR-spectroscopy. Protein expression of alkaline phosphatase, Axin, β-catenin and Sox9 were quantified by western blotting. In 58% of the VIC preparations, calcification was induced in an osteogenic culture medium and was accompanied by upregulation of alkaline phosphatase. The calcification induction was prevented by the XAV-939 co-treatment and the alkaline phosphatase upregulation was suppressed. As expected, Axin was upregulated, but the levels of active non-phospho-β-catenin were also enhanced. Sox9 was induced during XAV-939 treatment but apparently not as a result of downregulation of β-catenin signalling. XAV-939 was therefore able to prevent calcification of human VIC cultures, and XAV-939 treatment was accompanied by upregulation of active non-phospho-β-catenin. Although XAV-939 does not downregulate active β-catenin, treatment with XAV-939 results in Sox9 upregulation that may prevent the calcification process