One single dose of antegrade cold HTK cardioplegic solution in elective mitral valve surgery protects the myocardium equally well as repetitive antegrade cold blood cardioplegia.

Inflammation is central to heart failure progression. Innate immune signaling increases expression of the transmembrane proteoglycan syndecan-4 in cardiac myocytes and fibroblasts, followed by shedding of its ectodomain. Circulating shed syndecan-4 is increased in heart failure patients, however the pathophysiological and molecular consequences associated with syndecan-4 shedding remain poorly understood. Here we used lipopolysaccharide (LPS) challenge to investigate the effects of syndecan-4 shedding in the heart. Wild-type mice (10mg/kg, 9h) and cultured neonatal rat cardiomyocytes and fibroblasts were subjected to LPS challenge. LPS increased cardiac syndecan-4 mRNA without altering full-length protein. Elevated levels of shedding fragments in the myocardium and blood from the heart confirmed syndecan-4 shedding in vivo. A parallel upregulation of ADAMTS1, ADAMTS4 and MMP9 mRNA suggested these shedding enzymes to be involved. Echocardiography revealed reduced ejection fraction, diastolic tissue velocity and prolonged QRS duration in mice unable to shed syndecan-4 (syndecan-4 KO) after LPS challenge. In line with syndecan-4 shedding promoting immune cell recruitment, expression of immune cell markers (CD8, CD11a, F4/80) and adhesion receptors (Icam1, Vcam1) were attenuated in syndecan-4 KO hearts after LPS. Cardiomyocytes and fibroblasts exposed to shed heparan sulfate-substituted syndecan-4 ectodomains showed increased Icam1, Vcam1, TNFα and IL-1β expression and NF-κB-activation, suggesting direct regulation of immune cell recruitment pathways. In cardiac fibroblasts, shed ectodomains regulated expression of extracellular matrix constituents associated with collagen synthesis, cross-linking and turnover. Higher syndecan-4 levels in the coronary sinus vs. the radial artery of open heart surgery patients suggested that syndecan-4 is shed from the human heart. Our data demonstrate that shedding of syndecan-4 ectodomains is part of the cardiac innate immune response, promoting immune cell recruitment, extracellular matrix remodeling and mitigating cardiac dysfunction in response to LPS.

Background Pressure overload of the heart occurs in patients with hypertension or valvular stenosis and induces cardiac fibrosis because of excessive production of extracellular matrix by activated cardiac fibroblasts. This initially provides essential mechanical support to the heart, but eventually compromises function. Osteopontin is associated with fibrosis; however, the underlying signaling mechanisms are not well understood. Herein, we examine the effect of thrombin‐cleaved osteopontin on fibrosis in the heart and explore the role of syndecan‐4 in regulating cleavage of osteopontin. Methods and Results Osteopontin was upregulated and cleaved by thrombin in the pressure‐overloaded heart of mice subjected to aortic banding. Cleaved osteopontin was higher in plasma from patients with aortic stenosis receiving crystalloid compared with blood cardioplegia, likely because of less heparin‐induced inhibition of thrombin. Cleaved osteopontin and the specific osteopontin peptide sequence RGDSLAYGLR that is exposed after thrombin cleavage both induced collagen production in cardiac fibroblasts. Like osteopontin, the heparan sulfate proteoglycan syndecan‐4 was upregulated after aortic banding. Consistent with a heparan sulfate binding domain in the osteopontin cleavage site, syndecan‐4 was found to bind to osteopontin in left ventricles and cardiac fibroblasts and protected osteopontin from cleavage by thrombin. Shedding of the extracellular part of syndecan‐4 was more prominent at later remodeling phases, at which time levels of cleaved osteopontin were increased. Conclusions Thrombin‐cleaved osteopontin induces collagen production by cardiac fibroblasts. Syndecan‐4 protects osteopontin from cleavage by thrombin, but this protection is lost when syndecan‐4 is shed in later phases of remodeling, contributing to progression of cardiac fibrosis.

Antegrade cold blood cardioplegia provides better myocardial protection than cold crystalloid cardioplegia in patients undergoing aortic valve replacement.

Objective: When aortic valve replacement is needed, a biological valve is usually implanted in patients older than age 60 to 65 years. A large valvular opening area is important to avoid prosthesis-patient mismatch and facilitate reverse left ventricular remodeling. The Trifecta biological valve (St Jude Medical, St Paul, Minn) is, because of its design, believed to reduce transvalvular gradient compared with other biological valves, especially in smaller annuli. Several retrospective studies have compared transvalvular gradients of implanted valves prostheses using the respective manufacturers given size and not the actual annulus size measured by a metric sizer. This makes comparison of the hemodynamic properties of different valve brands and sizes difficult. We therefore performed a prospective randomized study, using the same metric sizer to measure annulus size, and compared hemodynamic profiles of the Trifecta to our standard Mosaic Ultra biological valve (Medtronic, Minneapolis, Minn).Methods: Ninety elective patients with small to medium annulus diameter undergoing aortic valve replacement were randomized to either Trifecta or Mosaic Ultra. After native valve removal and decalcification, a Hegar-sizer was used to measure true annulus size. Then the largest possible valve of either brand was implanted according to the randomization protocol. Echocardiography was performed 6 months postoperatively.