Closed, Phosphorylcholine-Coated Circuit and Reduction of Systemic Heparinization for Cardiopulmonary Bypass: The Intraoperative ECMO Concept

Abstract

Cardiopulmonary bypass with heparin-bonded circuits reduces systemic heparinization which is associated to a better clinical outcome in cardiac operations. In the present study, a novel biocompatible treatment, based on a phosphorylcholine coating without heparin, has been used to reduce systemic heparinization during cardiopulmonary bypass. Sixty patients underwent coronary revascularization with a fully phosphorylcholine-coated circuit. The circuit was entirely closed; suctions from the field were separated during the cardiopulmonary bypass time. A low systemic heparinization protocol based on half the loading dose of heparin (150 lU/kg) and a target activated clotting time of 320 seconds was applied. No thrombus formation inside the extracorporeal circulation circuit occurred; in-hospital mortality was absent. One patient (1.6%) had a postoperative myocardial infarction and 2 (3.3%) were surgically revised due to bleeding. Homologous blood transfusion rate was 11.6%, postoperative bleeding was 310 ± 136 ml. If compared to patients treated with heparin-coated circuits and low systemic heparinization, these patients have better platelet count preservation and lower postoperative bleeding. The low thrombogenicity of phosphorylcholine-treated surfaces, despite the absence of surface-immobilized heparin, allows a safe reduction of systemic heparinization in the setting of an ECMO-like intraoperative cardiopulmonary - bypass. This intraoperative ECMO approach offers promising results in terms of clinical outcome after coronary revascularization operations.

The effect of a polyurethane coating incorporating both a thrombin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation

“…Previous work from our laboratory and other investigators have established that NO releasing polymers (NORel) can prevent loss of circulating platelets and monocytes, prevent up to 75% of ECC thrombus formation and maintain preservation of platelet function to normal exogenous stimuli by inhibiting ECC-induced activation [1,5,26–32]. Together, these pieces of evidence provide a strong importance for NO in defining, in part, the hemocompatibility of biomaterials used in ECLS and confirms why normal vascular endothelium provides such a beneficial nonthrombogenic surface.…”

“…Rabbit platelet aggregation was assayed based on the Born’s turbidimetric method using a Chrono-Log optical aggregometer as previously described [1]. Briefly, citrated blood (1:10 blood to ACD) was collected (6 ml) and platelet-rich plasma (PRP) was obtained by centrifugation at 110 × g for 15 min.…”

“…The major complications are clotting in the device and bleeding from the patient. Systemic anticoagulation blocks fibrin formation but does not prevent platelet adhesion and activation [1, 2]. In an attempt to reduce the activation of platelets at the blood/material surface interface, we and other investigators have developed surface coatings that mimic the vascular endothelium and preserve platelet quiescence in the extracorporeal circuits (ECC).…”

Coatings for cardiovascular devices: coronary stents

“…This, in turn, leads to reduced cellular adhesion and clinically this has been shown to provide for less activation of blood (Gobeil et al, 2002;Ranucci et al, 2002) and reduced infl ammatory response (Goreish et al, 2004). The PC group carries both negative and positive charges (zwitterionic) which makes it polar and very hydrophilic, but it is overall charge neutral, which is important to minimise unwanted interactions with biomolecules such as proteins.…”

MECC Equipment

“…Skrabal et al failed to detect signi fi cant bene fi t with PMEA coating [ 51 ] . Other new developments of coating systems for CPB materials have shown promising results [52][53][54] .…”