Abstract 16305: Microbubble and Ultrasound Mediated Thromboprophylaxis in Porcine Models of Extracardiac Shunts
Background: Palliative shunts in congenital heart disease patients are vulnerable to thrombotic occlusion. High mechanical index (MI) impulses from a modified diagnostic ultrasound (US) transducer during a systemic microbubble (MB) infusion have been utilized to dissolve intravascular thrombi without anticoagulation, and we sought to determine whether this technique could be used prophylactically to reduce thrombus burden within surgically placed extracardiac shunts.
Methods: Three separate 4mm Propaten vascular shunts (W.L Gore, Flagstaff, AZ) of 2.5cm length were surgically placed in each of 18 pigs: (1) a right-sided end to side arteriovenous (AV, carotid-jugular) shunt, (2) left-sided arterio-arterial (AA, carotid-carotid) and (3) venovenous (VV, jugular-jugular) interposition shunts. Transcutaneous, randomized, weekly 30-minute treatments (total 4 treatments) of either guided high MI US+MB (n=6; Group 1) using a 3% MRX-801 MB infusion, or US alone (n=6 pigs; Group 2) were given separately to each shunt. The third group of pigs (n=6) received no treatments. The shunts were explanted after 4 weeks and analyzed by histopathology for quantification of luminal thrombus area (mm2) for the entire length of the each shunt. No pigs received antiplatelet or anticoagulants during the treatment period.
Results: Eighteen pigs (mean weight 37.4 ± 3.4 kg) with 54 shunts were studied. The overall thrombus burden (mm2) was higher in VV shunts (5.6 ± 2.8) compared to AA (3.8± 3, p=0.001), but there was no significant difference between AV (3.9± 3) and AA (p=0.864) or AV and VV (p=0.104). Group 1 had less thrombus burden (2.0 ± 1.4 mm2) in the AV shunts compared to group 2 (4.8 ± 3.2 mm2, p=0.03) and group 3 (4.9 ± 3.0 mm2, p=0.04). No difference in thrombus burden was seen between groups for AA and VV shunts.
Conclusion: Transcutaneous US and intravenous MB are capable of decreasing thrombus burden in arteriovenous shunts without the need for antiplatelet agents, and may be a method of preventing palliative shunt occlusion in children
- © 2013 by American Heart Association, Inc.