Improved blood cellular biocompatibility with heparin coated circuits during cardiopulmonary bypass

The clinical use of heparinized surfaces in the extracorporeal circuit was studied to find out if there was any blood cell rheologic benefit to support its use in routine low risk cardiac surgery.

In a prospective single blind study, 39 patients were operated upon with the heart lung machine for angina pectoris by coronary bypass grafting and were randomized to a control group or a heparin group. Blood cell rheology was analysed using the St. George filtrometer where damage to the red blood cells and white blood cells was estimated by assessing deformability reductions, transit, time increases and clogging rate and clogging particle changes.

At the end of cardiopulmonary bypass, in the heparin group, the red cell filterability (rFR) and the white cell filterability (WFR) were 8% better than in the control group (p=0.0079 and p=0.027 respectively). The red cell transit time was 19% slower in the control group (p=0.0351). The red cell clogging rate (RCR) and clogging particles (RCP) were significantly lower in the heparin group (p=0.0212 and p=0.0409 respectively. The white cell clogging rate (WCR) and clogging particles (WCP) showed a similar pattern.

In spite of these significant differences the clinical outcome was similar in the groups. Thus heparin coating of the extracorporeal circuit reduces blood cell rheologic damage significantly in low risk patients undergoing routine bypass surgery for angina but this use did not lead to any clinical benefit postoperatively. Therefore the use of such circuits for routine low risk cardiac surgery cannot be recommended.