Increased Cardiac Myocyte PDE5 Levels in Human and Murine Pressure Overload Hypertrophy Contribute to Adverse LV Remodeling

Background: The intracellular second messenger cGMP protects the heart under pathological conditions. We examined expression of phosphodiesterase 5 (PDE5), an enzyme that hydrolyzes cGMP, in human and mouse hearts subjected to sustained left ventricular (LV) pressure overload. We also determined the role of cardiac myocyte-specific PDE5 expression in adverse LV remodeling in mice after transverse aortic constriction (TAC). Methodology/Principal Findings: In patients with severe aortic stenosis (AS) undergoing valve replacement, we detected greater myocardial PDE5 expression than in control hearts. We observed robust expression in scattered cardiac myocytes of those AS patients with higher LV filling pressures and BNP serum levels. Following TAC, we detected similar, focal PDE5 expression in cardiac myocytes of C57BL/6NTac mice exhibiting the most pronounced LV remodeling. To examine the effect of cell-specific PDE5 expression, we subjected transgenic mice with cardiac myocyte-specific PDE5 overexpression (PDE5-TG) to TAC. LV hypertrophy and fibrosis were similar as in WT, but PDE5-TG had increased cardiac dimensions, and decreased dP/dtmax and dP/dtmin with prolonged tau (P<0.05 for all). Greater cardiac dysfunction in PDE5-TG was associated with reduced myocardial cGMP and SERCA2 levels, and higher passive force in cardiac myocytes in vitro. Conclusions/Significance: Myocardial PDE5 expression is increased in the hearts of humans and mice with chronic pressure overload. Increased cardiac myocyte-specific PDE5 expression is a molecular hallmark in hypertrophic hearts with contractile failure, and represents an important therapeutic target

A 3D+time spatio-temporal model for joint segmentation and registration of sparse cardiac cine MR image stacks

We previously developed a hybrid spatio-temporal method for the segmentation of the left ventricle in 2D+time magnetic resonance (MR) image sequences and here extend this model-based approach towards 3D+time sparse stacks of cine MR images with random orientation. The presented method combines an explicit landmark based statistical geometric model of the inter-subject variability at the end-diastolic and end-systolic time frames with an implicit geometric model that constraints the intra-subject frame-to-frame temporal deformations through deterministic non-rigid image registration of adjacent frames. This hybrid model is driven by both local and global intensity similarity, resulting in a combined spatio-temporal segmentation and registration approach. The advantage of our hybrid model is that the segmentation of all image slices and of the whole sequence can be performed at once, guided by shape and intensity information of all time frames. In addition, prior shape and intensity knowledge are incorporated in order to cope with ambiguity in the images, while keeping training requirements limited. © 2012 Springer-Verlag.Elen A., Hermans J., Hermans H., Maes F., Suetens P., ''A 3D+time spatio-temporal model for joint segmentation and registration of sparse cardiac cine MR image stacks'', Lecture notes in computer science, vol. 7085, pp. 198-206, 2011 (Workshop on statistical atlases and computational models of the heart: imaging and modelling challenges - STACOM, in conjunction with MICCAI 2011, September 22, 2011, Toronto, Canada).status: publishe

A randomized assessment of an advanced tissue preservation technology in the juvenile sheep model

Despite improved anticalcification technology, bioprosthetic heart valves still cannot be used in younger patients because of progressive structural valve degeneration. A novel advanced tissue preservation technology was developed that uses stable functional group capping and preservation by glycerolization. Valves incorporating this novel technology can be stored in a dry condition and do not require rinsing before use. The aim of the study was to assess the effects of this new technology in terms of valve function and durability in a chronic sheep model of orthotopic implantation.status: publishe

Effect of sutureless implantation of the Perceval S aortic valve bioprosthesis on intraoperative and early postoperative outcomes

ObjectiveProlonged aortic crossclamping can increase mortality and morbidity after aortic valve replacement in elderly and high-risk patients. Sutureless implantation of the prosthesis has the potential to shorten aortic crossclamp time.MethodsThe Perceval S valve (Sorin Biomedica Cardio Srl, Sallugia, Italy), a sutureless implantable aortic bioprosthesis, was used in 32 patients (median age, 78 years; median logistic euroSCORE, 9.99) requiring aortic valve replacement with or without concomitant coronary artery bypass grafting. Hemodynamic parameters and clinical outcome were obtained at discharge, at 6 months, and up to 1 year postoperatively.ResultsAortic crossclamp time needed for aortic valve replacement was 18 ± 6 minutes. Hemodynamics at discharge showed good function of all Perceval S valves with low transvalvular pressure gradients (mean, 12 ± 5 mm Hg and peak, 23 ± 9 mm Hg) and low incidence of paravalvular or valvular leakage. Operative mortality was 0%. Follow-up at 1 year showed 3 non–valve-related deaths. Survivors showed good clinical outcome and stable hemodynamic function of the valve prosthesis, except for 1 patient in whom endocarditis developed. Despite a moderate decrease in platelet counts persisting up to 12 months, freedom of bleeding and thromboembolic events was 100%.ConclusionsIt is possible to implant a well-functioning sutureless stent-mounted valve in the aortic position in less than 20 minutes of aortic crossclamping. This is associated with excellent early clinical and hemodynamic outcome in high-risk patients. Moderate changes in hematologic parameters persisted but were not related to clinical events

Increased Cardiac Myocyte PDE5 Levels in Human and Murine Pressure Overload Hypertrophy Contribute to Adverse LV Remodeling

BACKGROUND: The intracellular second messenger cGMP protects the heart under pathological conditions. We examined expression of phosphodiesterase 5 (PDE5), an enzyme that hydrolyzes cGMP, in human and mouse hearts subjected to sustained left ventricular (LV) pressure overload. We also determined the role of cardiac myocyte-specific PDE5 expression in adverse LV remodeling in mice after transverse aortic constriction (TAC). METHODOLOGYPRINCIPAL FINDINGS: In patients with severe aortic stenosis (AS) undergoing valve replacement, we detected greater myocardial PDE5 expression than in control hearts. We observed robust expression in scattered cardiac myocytes of those AS patients with higher LV filling pressures and BNP serum levels. Following TAC, we detected similar, focal PDE5 expression in cardiac myocytes of C57BL/6NTac mice exhibiting the most pronounced LV remodeling. To examine the effect of cell-specific PDE5 expression, we subjected transgenic mice with cardiac myocyte-specific PDE5 overexpression (PDE5-TG) to TAC. LV hypertrophy and fibrosis were similar as in WT, but PDE5-TG had increased cardiac dimensions, and decreased dP/dtmax and dP/dtmin with prolonged tau (P<0.05 for all). Greater cardiac dysfunction in PDE5-TG was associated with reduced myocardial cGMP and SERCA2 levels, and higher passive force in cardiac myocytes in vitro. CONCLUSIONSSIGNIFICANCE: Myocardial PDE5 expression is increased in the hearts of humans and mice with chronic pressure overload. Increased cardiac myocyte-specific PDE5 expression is a molecular hallmark in hypertrophic hearts with contractile failure, and represents an important therapeutic target.status: publishe