No abstract

Background and Purpose-Endovascular treatment of cerebral aneurysms, a minimally invasive alternative to surgery, is too often followed by recanalization and recurrences. The purpose of this work was to assess if in situ beta radiation can inhibit recanalization after coil embolization. Methods-Radioactive platinum coils ( 32 P-coils) were produced by ion implantation of 32 P. A single-coil arterial occlusion model was used to compare angiographic and pathological results at 1 to 12 weeks after nonradioactive and 32 P-coil embolization of maxillary, cervical, and vertebral arteries in 26 dogs. Coils of varying activities were used and results compared to define the minimal activity required to inhibit recanalization. Similar experiments were performed in 16 porcine maxillary and lingual and 8 rabbit axillary arteries. Results of 32 P-coil embolization of bifurcation aneurysms were then compared with embolization with nonradioactive coils in 12 dogs at 3 months. Results-Nonradioactive coil embolization of canine arteries led to occlusion at 1 week, followed by recanalization at 2 weeks, which persisted at 3 months in all cases. 32 P-coils, ion-implanted with activities above 0.13 Ci/cm, led to persistent occlusion at 3 months in 80% of arteries.32 P-coils ion-implanted with the same activity inhibited recanalization in porcine and rabbit arteries. Bifurcation aneurysms treated with 32 P-coils had better angiographic results at 3 months (Pϭ0.006) than aneurysms treated with nonradioactive coils. Arteries occluded were filled with fibrous tissue at 3 months. Aneurysms embolized with 32 P-coils showed more complete neointimal coverage of the neck, without recanalization, as compared with aneurysms treated with nonradioactive coils. Conclusion-In

BACKGROUND AND PURPOSE:Braided self-expandable stents and flow diverters of uniform construction may develop zones of heterogeneous porosity in vivo. Unwanted stenoses may also occur at the extremities of the device. We studied these phenomena in dedicated benchtop experiments.

BACKGROUND AND PURPOSE:FDs are new intracranial stents designed to occlude aneurysms while preserving flow to jailed arterial branches. We tested this fundamental principle in a new aneurysm model.

No abstract

Flow diverters may succeed in treating straight sidewall aneurysms, but the same device repeatedly fails to occlude curved sidewall and end-wall bifurcation aneurysms. In vivo studies can be designed to test basic principles that, once validated, may serve to guide clinical use of new devices.

We have compared the effects of inhaled nitric oxide (iNO) and i.v. nitroglycerin (ivGTN) on the haemodynamic response to phenylephrine-induced hypertension (PEHT) in anaesthetized pigs. PEHT did not change either pulmonary vascular resistance or gas exchange throughout all experiments. Both treatments lowered pulmonary arterial pressure to the same extent (-12.4% iNO; -13.7% ivGTN) and passively via an effect on left atrial pressure (-26.3% iNO; -31.4% ivGTN). Both treatments failed to reverse the decrease in renal blood flow (RBFc) induced by PEHT, but both increased urinary flow (UF) (+128% iNO; +148% ivGTN). IvGTN significantly increased plasma concentrations of nitrite and nitrate during (+22.7% arterial blood; +26.2% venous blood) and beyond the period of infusion (iNO: +6.4% and +4.9%, respectively). In four control pigs (no PEHT), iNO markedly increased RBFc (+109%), glomerular filtration rate (+72.5%) and UF (+68.7%). We conclude that iNO may have direct cardiac and renal effects, probably via intervention of NO carrier forms such as S-nitroso compounds.

Alterations in porosity may occur following in vivo implantation.