Comparison of Sarns 3M heparin bonded to Duraflo II and control circuits in a porcine model: macro- and microanalysis of thrombi accumulation in circuit arterial filters

Currently available biomaterials for use in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) represents one of the most important technical innovations in healthcare history, yet the systemic responses to CPB remain a fundamentally unresolved problem. Study of the blood-biomaterial interaction and development of biocompatible materials is intimately related to efforts to optimize patient outcome following CPB. This article reviews the design innovations in biomaterial surfaces that have been introduced into clinical practice in an attempt to ameliorate the detrimental consequences of CPB, contrasting the actual clinical improvements and patient benefits achieved against those predicted on the basis of theory and in vitro testing. Some discussion of the underlying mechanisms of action as presently understood is provided and the current limitations of biomaterial-dependent strategies to improve outcome following CPB are addressed.

Fabrication and in vivo thrombogenicity testing of nitric oxide generating artificial lungs

Hollow fiber artificial lungs are increasingly being used for long-term applications. However, clot formation limits their use to 1-2 weeks. This study investigated the effect of nitric oxide generating (NOgen) hollow fibers on artificial lung thrombogenicity. Silicone hollow fibers were fabricated to incorporate 50 nm copper particles as a catalyst for NO generation from the blood. Fibers with and without (control) these particles were incorporated into artificial lungs with a 0.1 m(2) surface area and inserted in circuits coated tip-to-tip with the NOgen material. Circuits (N = 5/each) were attached to rabbits in a pumpless, arterio-venous configuration and run for 4 h at an activated clotting time of 350-400 s. Three control circuits clotted completely, while none of the NOgen circuits failed. Accordingly, blood flows were significantly higher in the NOgen group (95.9 ± 11.7, p < 0.01) compared to the controls (35.2 ± 19.7; mL/min), and resistance was significantly higher in the control group after 4 h (15.38 ± 9.65, p < 0.001) than in NOgen (0.09 ± 0.03; mmHg/mL/min). On the other hand, platelet counts and plasma fibrinogen concentration expressed as percent of baseline in control group (63.7 ± 5.7%, 77.2 ± 5.6%; p < 0.05) were greater than those in the NOgen group (60.4 ± 5.1%, 63.2 ± 3.7%). Plasma copper levels in the NOgen group were 2.8 times baseline at 4 h (132.8 ± 4.5 μg/dL) and unchanged in the controls. This study demonstrates that NO generating gas exchange fibers could be a potentially effective way to control coagulation inside artificial lungs.

Transfusion protocol for implantation and explantation of cardiac devices in an academic medical center

Few reports in the literature describe the transfusion support needed for implantation and explantation of cardiac assist devices. Because such devices are frequently used at this institution, we have established a protocol to support these patients. We reviewed blood bank records to document the usage of blood components in all patients on cardiac assist devices from 1989 to 2005 (n = 215). The data were separated into components given at the time of implantation and explantation of the device. Implantation data on 214 patients showed the mean use as follows: red blood cells (RBC), 5.7 U; platelets (PLT), 2.4 U; fresh frozen plasma (FFP), 7.5 U; and cryoprecipitate, 0 U. Explantation data on 134 patients showed a mean use as follows: RBC, 7.7 U; PLT, 2.4 U; FFP, 9.9 U; and cryoprecipitate, 3.7 U. Our protocol for the preparation of blood components for implantation and explantation of a cardiac device is, implantation: RBC, 4 U; PLT, 1 U; FFP, 6 U; explantation: RBC, 8 U; PLT, 2 U; FFP, 8 U. Our data do not support the need for preparation of cryoprecipitate before implantation or explantation.

Heparin-coated balloon-expandable stent reduces intimal hyperplasia in the iliac artery in baboons

PURPOSE

To examine the effect of heparin-coated balloon-expandable iliac stent placement on intimal hyperplasia in a baboon model.

MATERIALS AND METHODS

Balloon-expandable (Palmaz-Schatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated iliac stent was placed on one side and the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at 30 days (n = 10) and 90 days (n = 10). Arteriography was performed to assess iliac patency and intravascular ultrasonography was used to determine neointimal and luminal areas. Histologic and morphometric analysis and scanning electron microscopy were performed in the stent-implanted iliac arteries.

RESULTS

One animal was excluded in the 30-day group because of premature death. In the remaining nine surviving animals, seven control stents (78%) and nine heparin-coated stents (100%) remained patent. Morphometric analysis showed that the iliac arteries with heparin-coated stents had larger luminal areas (17%, P <.05), less neointimal area (26%, P <.05), lower neointima-to-media ratios (32%, P <.05), and equivalent medial areas (P =.92) compared to the control group at 30 days. In contrast, all control and heparin-coated stents were patent (100%) in the 90-day group. In that group, the heparin-coated stent group had less neointimal area (28%, P <.05), lower neointima-to-media ratios (42%, P <.05), and equivalent medial area (P =.92) and luminal area (P =.07) compared to the control group.

CONCLUSIONS

The data demonstrate that heparin-coated balloon-expandable stents reduce intimal hyperplasia after iliac artery stent placement. This approach may represent a useful strategy for prolonging luminal patency after iliac stent placement.