Clinical Research Directory

Flow-Based Platelet Function Assessment Using Total Thrombus-Formation Analysis System (T-TAS) and Early Bleeding After Cardiac Surgery With Cardiopulmonary Bypass (CPB)

The goal of this observational study is to learn how flow-based platelet function measured with the Total Thrombus-formation Analysis System (T-TAS) relates to early postoperative bleeding in adults undergoing cardiac surgery with cardiopulmonary bypass. The study will also evaluate how T-TAS changes during the perioperative period and how it compares with standard coagulation and platelet function tests. The main questions it aims to answer are: Is lower post-cardiopulmonary bypass T-TAS Platelet-chip (PL-chip) thrombus formation associated with increased postoperative chest tube drainage during the first 12 hours after surgery? How do T-TAS parameters change before surgery, immediately after cardiopulmonary bypass, and 24 hours after surgery? Are abnormal T-TAS results associated with blood transfusion requirements, major bleeding, re-exploration for bleeding, and length of stay in the intensive care unit and hospital? Does T-TAS provide complementary information compared with standard coagulation tests, von Willebrand factor (vWF) measurements, platelet aggregometry, and viscoelastic testing? Participants will: Undergo blood sampling at three predefined perioperative time points: before anesthesia induction, immediately after cardiopulmonary bypass and heparin reversal with protamine, and 24 hours after surgery Have T-TAS testing, standard laboratory coagulation tests, vWF testing, platelet aggregometry, and viscoelastic testing performed on collected samples Have clinical, surgical, transfusion, and postoperative bleeding data collected during their hospital stay The study is observational and does not require changes to routine clinical care or perioperative management.

Endothelial Colony-Forming Cells in Patients With VWD, AVWS and Healthy Subjects

The goal of this observational study is to learn how endothelial colony-forming cells (ECFCs) behave in people with von Willebrand disease (VWD), acquired von Willebrand syndrome (AVWS), and in healthy individuals.

Assessment of Paravalvular Leak After TAVI by Hemodynamic Measurements and Cardiac MRI

Rationale: Transcatheter aortic valve implantation (TAVI) has become the standard therapy for elderly patients with high surgical risks. Paravalvular leakage after TAVI is relatively common and there is conflicting evidence regarding the clinical impact of mild paravalvular leakage in self-expanding devices. Prospective data for self-expanding devices are required to compare the extent of paravalvular leakage as a result of device design. Grading paravalvular leakage after TAVI is difficult. Echocardiography and angiography systematically underestimate paravalvular leakage (PVL) as compared to cardiac MRI. Hemodynamic measurements are used to aid decision making directly after TAVI implantation. Prospective data comparing hemodynamic measurements with cardiac MRI are needed to design an optimal strategy to grade paravalvular leakage peri-operatively in order to optimize TAVI outcomes. The combination of aortic valve stenosis, angiodysplasia and von Willebrand Disease type 2A (vWD-2A) is known as Heyde syndrome. Previous studies have shown a decrease in angiodysplastic lesions after TAVI. However, since PVL after TAVI is relatively common, angiodysplastic lesions tend to reoccur. Prospective data comparing the severity of PVL to the severity of both vWD-2A and angiodysplasia are lacking. Objective: To assess procedural hemodynamic measurements in patients with paravalvular regurgitation quantified by means of cardiac MRI (CMR) and to analyse its association with impaired clinical outcome during 5-year follow-up. Secondary objectives are to assess whether the severity of vWD-2A correlates with the severity of PVL measured by cardiac MRI, and to prospectively assess the success percentage of TAVI in the treatment of angiodysplasia. Study design: This is a prospective, single-center clinical trial. Patients will receive a TAVI. After implantation different hemodynamic indices of PVL will be assessed. Within 4-8 weeks after TAVI a cardiac MRI will be performed to quantify the amount of PVL. Standardized clinical follow-up will take place at discharge, 30 days, 3 months, 6 months and 1 year. Telephone follow-up will take place at 2, 3, 4 and 5 years after TAVI. In patients with known angiodysplasia or iron deficiency anemia e.c.i., a videocapsule endoscopy (VCE) will take place before TAVI and 6 months after TAVI. Of note, for the substudy on Heyde syndrome, patients with a different type of TAVI valve (i.e. no Abbott Portico valve) are also allowed to participate. Study population: Approximately 80 patients with severe symptomatic aortic valve stenosis with an indication for TAVI will be included. At least 76 patients with a cardiac MRI that is of sufficient quality to quantify the amount of PVL will be included. Intervention: Patients will undergo cardiac MRI on top of standard clinical care within 4-8 weeks after TAVI. A subgroup of patients will also undergo a VCE. Main study parameters/endpoints: The primary endpoint is defined as PVL regurgitation fraction as measured by cardiac MRI. One secondary endpoint will comprise a composite of device success, early safety and clinical efficacy as defined by the Valve Academic Research Consortium-2 (VARC-2) (1) and will comprise death, vascular complications, stroke/TIA, life-threatening bleeding requiring transfusion, and acute kidney injury requiring dialysis. Another secondary endpoint will be the reduction of angiodysplastic lesions after TAVI as determined by VCE. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The hemodynamic indices can be assessed in a standard fashion using a fluid filled pigtail catheter that is placed in the left ventricle as part of the routine protocol. Following TAVI, enrolled patients will undergo cardiac MRI to assess PVL. The risk of cardiac MRI after TAVI implantation is negligible. Extra blood samples will be taken. After one year, patients will be followed by telephonic follow-up. Risk/benefit: the expected benefit is a structured clinical follow-up at 1, 2, 3, 4 and 5 years, at the cost of an extra visit to undergo cardiac MRI.