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.
