Boundary layer drug delivery using a helical catheter

Safety and efficacy study of prourokinase injection during primary percutaneous coronary intervention in acute ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate the efficacy and safety of intracoronary administration of prourokinase via balloon catheter during primary percutaneous coronary interventions in patients with acute ST-segment elevation myocardial infarction.

METHODS

Acute ST-segment elevation myocardial infarction patients underwent primary percutaneous coronary interventions were randomly divided into two groups: intracoronary prourokinase group (n = 125) and control group (n = 135). During primary percutaneous coronary interventions, prourokinase or saline was injected to the distal end of the culprit lesion via balloon catheter after balloon catheter dilatation. Demographic and clinical characteristics, infarct size, myocardial reperfusion, and cardiac functions were evaluated and compared between two groups. Hemorrhagic complications and major averse cardiovascular events (MACE) occurred in the 6-months follow-up were recorded.

RESULTS

No significant differences were observed between two groups with respect to baseline demographic, clinical, and thrombolysis in myocardial infarction grade (P > 0.05). In the intracoronary prourokinase group, more patients had ST-segment resolution (>50%) compared with control group (P < 0.05). Patients in the intracoronary prourokinase group showed lower levels of serum CK, creatine kinase-MB fraction, and troponin I than those in control group (P < 0.05). No significant differences in bleeding complications were observed between the two groups (P > 0.05). At 6-months follow-up, there was no statistically different of MACE between the two groups (P > 0.05).

CONCLUSIONS

Intracoronary administration of prourokinase via balloon catheter during primary percutaneous coronary interventions effectively improved myocardial perfusion and no increased bleeding in ST-segment elevation myocardial infarction patients.

A randomized study of prourokinase during primary percutaneous coronary intervention in acute ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate the efficacy and safety of intracoronary administration of prourokinase via balloon catheter during primary percutaneous coronary interventions (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Acute STEMI patients underwent primary PCI were randomly divided into two groups: intracoronary prourokinase (IP) group (n = 118) and control group (n = 112). During primary PCI, prourokinase or saline were injected to the distal end of the culprit lesion via balloon catheter after balloon catheter dilatation. Demographic and clinical characteristics, infarct size, myocardial reperfusion, and cardiac functions were evaluated and compared between two groups. Hemorrhagic complications and MACE occurred in the 6-months follow up were recorded.

RESULTS

No significant differences were observed between two groups with respect to baseline demographic, clinical, and angiographic characteristics (P > 0.05). In IP group, more patients had complete ST segment resolution (>70%) compared with control group (P < 0.05). Patients in IP group showed lower levels of serum CK, CK-MB and TnI, and a much higher myocardial blood flow (MBF) than those in control group (P < 0.05). No significant differences of TIMI major or minor bleeding complications were observed between the two groups (P > 0.05). At 6-months follow-up, there was a trend that patients in the IP group had a less chance to have MACE, though it was not statistically different (8.5% vs 12.5%, P > 0.05).

CONCLUSIONS

Intracoronary administration of prourokinase via balloon catheter during primary PCI effectively improved myocardial perfusion in STEMI patients.

Anticoagulant surface coating using composite polysaccharides with embedded heparin-releasing mesoporous silica

Release of heparin from the surface of biomaterials is a feasible and efficient manner for preventing blood coagulation because of the high bioactivity of free heparin and a low application dosage compared to intravenous injection of heparin. Here we report a novel method featuring a blend of heparin-loaded SBA-15, catechol-modified chitosan (CCS), and heparin as a heparin-releasing film. The release of heparin was based on its leakage from heparin-loaded amino-functionalized mesoporous silica SBA-15 (SBA-15-NH2), which was controlled by the amino density of the SBA-15-NH2. Heparin-loaded SBA-15-NH2, CCS, and heparin were mixed together, and the mixture was cast onto the surface of a polydopamine-modified substrate, forming a heparin-releasing film on the surface of the substrate. The polydopamine acted as an adhesive interlayer that stabilized the film coated on the substrate. The sustained release rates of heparin from the film ranged from 15.8 to 2.1 μg/cm(2)/h within 8 h. The heparin-releasing film showed low fibrinogen adsorption, platelet adhesion, and hemolysis rate, indicating that it has good blood compatibility. This new approach would be very useful for modifying the surface of versatile blood-contacting biomaterials and ultimately improve their anticoagulation performance.

Coils and tubes releasing heparin. Studies on a new vascular graft prototype

Coiled metallic guidewires find widespread use, for instance in interventional cardiology. It is known that release of heparin from the surface of guidewires is advantageous to prevent formation of thrombotic emboli. New coiled tubular structures, having larger inner and outer diameter as compared to guidewires, are presented. In theory these tubes can be used as interposition vascular grafts. Ten coiled tubes with an internal diameter of 690 microm were made. Five different adherent polymeric coatings with increasing hydrophilicity were used. Five tubes contained heparin in the coating and the other five were unheparinised controls. The five tubes containing heparin were studied with respect to heparin release in vitro (amount released, kinetics), and immobilised heparin that is exposed at the surface. All tubes were studied with a direct cell contact assay using 3T3 mouse fibroblast cells, a dynamic thrombin generation test, and endothelial cell growth onto the coils. It was found that the heparinised tubes lead to very little thrombin formation. It is argued that this is due to heparin that is immobilised and exposed at the inner surface of such tubes. Furthermore the coils showed to be cytocompatible and endothelial cells adhere and proliferate well onto the coils. This concept is believed to hold promise for further development of small vascular grafts.

Mechanisms of heparin transport through expanded poly(tetrafluoroethylene) vascular grafts

Thrombosis and neointimal hyperplasia limit the utility of small-caliber artificial vascular grafts. Surface modifications and adjunctive pharmacological therapy might mediate these complications. We examined the mechanisms by which a model vasoactive compound, heparin, transverses porous graft materials and how material modifications alters this drug's transport. The effective permeance of [(3)H]heparin was measured after application of a uniform concentration of drug to either the internal or external surface of the graft and in the presence or absence of pressure-driven physiologic hydraulic flows. Transgraft permeance was equivalent to those observed in normal arteries and, while enhanced by convection, was mediated in major part by diffusion. Peclet numbers under the various conditions examined ranged from 0.05 to 1.2, indicating that diffusive forces were equal to or exceeded convective forces in governing transmural heparin motion. Heparin traversed the graft even when applied from the outer perivascular surface, against adverse hydraulic flows. Modifications of the grafts that included a yarn barrier of spun poly(tetrafluoroethylene) or chemical modification of surface tension energy altered permeances as well. A unifying model for interpretation of these data incorporates the concept of entrapped air and surface tension energy in the graft. These characterizations allow for the design of vascular grafts that are optimized for pharmacotherapy to help prolong graft patency, especially in small-caliber vascular beds.

Local administration of ramiprilat is less effective than oral ramipril in preventing restenosis after balloon angioplasty in an animal model

PURPOSE

To test the hypothesis that local administration of angiotensin converting enzyme (ACE) inhibitor via a microporous balloon catheter would be more effective than oral administration of ACE inhibitor in preventing neointima formation after balloon angioplasty.

MATERIALS AND METHODS

Neointima formation was induced by balloon denudation followed by 0.5% cholesterol diet in 29 New Zealand White rabbits. Directly after denudation, local administration of 1.8 mg of ramiprilat (n = 7) or saline (n = 7) with a microporous balloon catheter at a pressure of 3 atm was performed. Both groups additionally received ramipril orally (1 mg/d). Seven animals were treated exclusively with oral ramipril. The control group was fed a 0.5% cholesterol diet and given no medication (n = 8). Six weeks after intervention, the animals were killed and morphometric and immunohistologic analyses were performed.

RESULTS

Oral administration of ramipril resulted in a significant reduction of placque area (-66%, P < .05). Oral and local administration of the ACE inhibitor was followed by a nonsignificant reduction of the neointimal area (-17%). Local administration of saline combined with oral ramipril failed to prevent neointimal formation (reduction of 6%, NS).

CONCLUSION

Oral administration of ramipril resulted in a significant reduction of neointimal proliferation in New Zealand White rabbits. The possible benefit of an additional administration of local ramiprilat was diminished by an excessive neointimal hyperplasia, which was most likely caused by the inherent vessel trauma with use of the microporous balloon catheter.