Measuring the ACT During Non-cardiac Arterial Procedures.

Overview

Aim of the MANCO study is to establish for once and for all that monitoring the effect of heparin during NCVI (Non-Cardiac Vascular Interventions) is essential to ensure the individual patient of safe and tailor-made anticoagulation. Not measuring the effect of the administered heparin exposes the patient to unnecessary risks of thrombo-embolic and bleeding complications. First aim of the MANCO study is to prove that the standardized bolus of 5000 IU of heparin, used by 90% of vascular specialists in Europe, results in inadequate anticoagulation in more than 80% of patients. These measurements will be performed using the Hemostasis Management System by Medtronic.

Heparin is used worldwide by all vascular surgeons and interventional radiologists (IR) during non-cardiac vascular interventions (NCVI), both open and endovascular. Heparin is used to reduce or prevent arterial thrombo-embolic complications (ATEC). Heparin reduces the clotting of blood and thereby coagulation. This also explains the negative side-effect of using heparin: its use can lead to bleeding-complications, possibly causing the need for blood tranfusions, more hematomas necessitating re-interventions and increasing the risk of infections. Since the 1970's it is well known that heparin has a non-linear dose response curve and also a non-linear elimination curve in the individual patient. Despite this fact, more than 95% of all vascular surgeons and IR use a standardized bolus of 5000 IU in every patient. Multiple studies have demonstrated that up to 70% of patients is not adequately anticoagulated during NCVI using that bolus of 5000 IU. During open or endovascular cardiac interventions the effect of heparin is always routinely measured using the activated clotting time (ACT). Despite this knowledge the percentage of vascular surgeons and/or IR that measure the effect of heparin during NCVI routinely is astonishing low: 0-5%, in the US this percentage is probably higher (30%), possibly due to medico-legal reasons. Existing guidelines on NCVI depict different regimes on the use of heparin or do not mention this use at all. The Hemostasis Management System (HMS, Medtronic) measures the ACT, but it also calculates a heparin dose response curve in the individual patient. This curve supplies the vascular surgeon or IR a tool to administer the exact amount of heparin needed to reach a desired ACT. Also the exact dose of protamine can be calculated to neutralize the effect of remaining circulating heparin in the individual patient. The use of the HMS in cardiac vascular procedures has to led to a reduced need for blood transfusions, less postoperative bleeding complications and a reduction of peri-procedural myocardial infarctions and other ATEC. To determine if the HMS can be of equal high value during NCVI, a pilot study was performed at the VUMC, called Hepvasc. Results of this pilot (submitted) and other sparse results from literature, show that HMS can be used during NCVI. Furthermore, results indicated that the bolus of 5000 IU resulted in inadequate anticoagulation in 7 out of 18 included patients. This exposes those patients to a higher risk of ATEC. As a result of this pilot, the MANCO study is designed with the HMS during NCVI. The MANCO study will evaluate the data of heparin management with the HMS in number of large vascular centers, starting in the Netherlands and after that in Europe. Measurements with the HMS will be used for the evaluation of the local heparin protocol by the individual vascular surgeon or IR. The MANCO study will be started permitting every center to apply their current heparin protocol. This includes the dosage of heparin and possible extra dosing of heparin to reach a desired ACT. The MANCO study is started as a prospective data registry and observational study of the ACT with an extensive case record form (CRF). Regular blood samples for ACT measurements will be done, so no extra invasive measurements are performed in the patient. Data will be collected according to all legal requirements and permission of local medical ethics committees is granted.