Haemostatic Markers in Cardiopulmonary Bypass

NCT03861286 | Completed

• 1 other identifier: 248558
• Study Type: observational
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

This study is to understand the changes occurring in a blood clotting protein, von Willebrand factor (VWF), in patients undergoing cardiac surgery who receive the blood thinner called Heparin. These patients are given Heparin through their veins, to prevent blood clot formation as it passes through the heart bypass machine. At the end of the operation, the effect of Heparin is reversed by another drug, Protamine Sulphate. Heparin prevents blood clots forming mainly by inactivating thrombin, a crucial protein needed for blood clotting. This effect of Heparin is monitored through blood tests called the 'Anti Factor-Xa' and the 'APTT'. Heparin has another effect on clotting: it can block the attachment of special blood cell fragments called platelets to damaged blood vessels, but this effect is not usually measured. Following blood vessel injury, the large VWF sticks to the damaged surface and captures platelets to form a 'plug' which stops bleeding. The platelet plug is then stabilised by other clotting proteins. This stops blood loss and allows vessel repair underneath. Heparin blocks the ability of VWF to capture platelets at the site of blood vessel injury. The higher the dose of Heparin, the greater this blocking effect is. This secondary effect of Heparin cannot be readily monitored and may explain why bleeding complications occur in patients receiving Heparin despite the monitoring with blood tests used. This study will look at the blood levels of Heparin, VWF and platelets before, during and after surgery and how well VWF functions in the presence of heparin, including its ability to attach to platelets. The investigators will determine if all of the heparin related changes in blood clotting can be detected using a method that looks at all of the different steps in forming a blood clot.

Conditions

Unfractionated Heparin; Cardiopulmonary Bypass Surgery

Keywords

Cardiopulmonary Bypass Surgery; Unfractionated Heparin

Outcome Measures

Primary Outcomes (1)

• Quantitative & Qualitative VWF Assessment

  VWF antigen level, Ristocetin Cofactor Assay

  6 months

Secondary Outcomes (1)

• Global Test of Haemostasis

  6 months

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

This is a prospective cohort study, and patients undergoing cardiopulmonary bypass surgery will be recruited when they are assessed pre operatively at the Royal Brompton Hospital (RBH) Normal controls will be staff members from Imperial College London. Patient recruitment: Patients who meet the inclusion criteria will be identified by the anaesthetic team when they are assessed preoperatively. They will be provided with a Participant Information Sheet and have the opportunity to ask questions and discuss the study with the researchers before providing consent. The study aims to recruit 30 patients.

You may qualify if:

• Patients undergoing first time cardiopulmonary bypass surgery for correction of atrial septal defects or tissue mitral valve repair
• Receiving intravenous Heparin for cardiopulmonary bypass

You may not qualify if:

• Concomitant Aortic Stenosis which is associated with an acquired von Willebrand Syndrome (aVWS)
• Patients with a baseline platelet count of \<100x109/L
• Patients with a known coagulation factor deficiency or platelet function disorder
• Patients receiving heparin therapy prior to CPB within last 7 days

Sponsors & Collaborators

• Imperial College London: lead
• Royal Brompton & Harefield NHS Foundation Trust: collaborator

Study Sites (1)

Royal Brompton Hospital

London, SW3 6NP, United Kingdom

Location

Related Publications (1)

• Sobel M, McNeill PM, Carlson PL, Kermode JC, Adelman B, Conroy R, Marques D. Heparin inhibition of von Willebrand factor-dependent platelet function in vitro and in vivo. J Clin Invest. 1991 May;87(5):1787-93. doi: 10.1172/JCI115198.

  PMID: 2022745 BACKGROUND

Biospecimen

Retention: SAMPLES WITHOUT DNA

Blood Samples

Study Officials

• Deepa Arachachillage, MBBS

  Imperial College London

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Consultant Haematologist

Study Record Dates

• First Submitted: March 1, 2019
• First Posted: March 4, 2019
• Study Start: February 15, 2019
• Primary Completion: July 18, 2019
• Study Completion: July 18, 2019
• Last Updated: September 25, 2019

Record last verified: 2019-09

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)