Intentional Stent Fractures in Congenital Heart Disease: When Breaking the Chains is the Only Way! Mehul B. Patel, MD, Henri Justino, MD CE Mullins Cardiac Catheterization Laboratories, Lillie Frank Abercrombie Section of Pediatric Cardiology, Texas Children’s Hospital, Baylor College of Medicine, Houston, Texas; Fellow: 4th year Introduction Results The Mullins principle states “Only place stents in children that can be dilated to an eventual adult size”. There are situations however when one may have to deploy a small sized stent or even jail a side branch. Such a stent may need serial dilatations to accommodate for vascular growth until it reaches the maximum rated diameter; beyond this point it cannot be further dilated, and results in a fixed obstruction within the vessel. Likewise the ostium of the jailed side branch may get progressively narrowed from endothelium growing over stent struts. With the widespread use of stents in small children there is now a growing need to manage this unique dilemma. There is a single report on the use of ultrahigh pressure balloons in the pulmonary arteries for successfully fracturing undersized stents.1 Hypothesis: Ultrahigh pressure balloons may be used to intentionally fracture stent side cells to allow side branch interventions, and also to induce longitudinal stent fracture to allow expansion of the stent beyond its rated diameter. Such interventions may avoid major vascular surgery. Objectives: To assess the safety and feasibility of intentional stent fractures using ultra high pressure balloon for stents deployed in a variety of anatomic locations There were 13 pts (11 males) with mean age 10.8 ± 12.4 years and mean weight 40.1 ± 33.9 kg at the time of attempted intentional stent fracture. All but two stent fracture attempts were performed by a single operator (HJ). The mean age at the time of first stent implantation was 5.8 ± 9.7 years. Types of stents were Genesis XD (n=2), Mega LD (n=1), Palmaz 4 series (n=2), Palmaz 8 series (n=3), “coronary” type (n=6; 2 drug-eluting). The initial stent diameters ranged from 4 to 13 mm. The primary sites for stent implantation included pulmonary veins (n=2), SVC/innominate veins (3), branch pulmonary arteries (5), coarctation (1), IVC/iliac veins (2) and RV-PA conduit (1) (Figure 2). Using noncompliant balloons such as Dorado (n=6), Atlas (n=4) and Conquest (n=3), longitudinal fracture was achieved in 7 pts and side cell expansion with strut fracture in 6; 1 had unsuccessful longitudinal stent fracture (Figure 3). The balloon diameters ranged from 4 to 14 mm and the inflation pressures ranged from 14 to >30 atm There were no procedural complications. One patient had balloon rupture during the procedure with no consequence. One side cell fracture allowed the implantation of a second stent through the newly created orifice. The mean follow up period was 1.8 ± 1.3 years with no clinical evidence of aneurysms or dissections by imaging (n=5). Abstract A stent placed during infancy and early childhood may need serial dilatations to accommodate for vascular growth until it reaches the maximum rated diameter. Beyond this point it cannot be further dilated. With continued growth the stented segment relatively and progressively narrows the vessel lumen causing fixed stenosis. Likewise the ostium of the jailed side branch may get progressively narrowed from the endothelium growing over stent struts trying to closing the side cells. With the widespread use of stents in small children there is now a growing need to manage this unique dilemma. We used ultrahigh pressure balloons (UHP) to induced side cell and longitudinal stent fractures in a variety of locations. Success was noted in 12/13 patients. There was no evidence of immediate or delayed vessel damage. Intentional fracture of stents (both longitudinal and side cell) is possible using ultra-high pressure balloons in pulmonary arteries, pulmonary veins, systemic veins, conduits and the aorta. No immediate signs of vessel wall injury was noted in any patient. In a subset of patients with follow up imaging there were no signs of vessel trauma on mid term follow up. 14 stented segments in 13 patients Stented segments were distributed at a variety of anatomic locations Procedure was successful in all but 1 patient (with 2 sites: SVC and innominate vein) There were no complications noted in any patient No evidence of immediate or delayed vessel damage Figure 2: Diagram showing the stented segments subjected to intentional stent fracture. Methods/Techniques Example of side cell fracture Example of Longitudinal fracture We conducted a retrospective study to asses the safety and feasibility of intentional stent fractures in patients who underwent interventions from January 2006 - December 2012. The study approved by Institutional Review Board of Baylor College of Medicine. For longitudinal stent fracture, the stented vessel was serially dilated until the maximal rated diameter of the stent  Ultrahigh pressure balloon of 1-2 mm larger diameter was chosen to induce fracture For side cell fracture, the side cell was crossed and serial dilations performed until cell was stretched wide with a residual waist noted  Ultrahigh pressure balloon of the same or 1-2 mm larger diameter was chosen to induce fracture (Figure 1). Example of in vitro longitudinal stent fracture Jailed and occluded right common iliac vein Narrowed right PA stented segment 4x8 mm Multilink vision open cell stent After serial balloon dilatations Full expansion with a compliant balloon until a discrete circular waist Stent reaches the maximum rated diameter; note the straight parallel stent rings Intentional Stent Fracture Balloon switched to an UHP non compliant balloon High pressure inflation Lateral view Longitudinal stent fracture after high pressure balloon inflation Side cell fractures and waist disappears Switched to UHP balloon of 1 mm larger diameter Longitudinal fracture Side cell fracture n = 7 n = 6 Stent in the main vessel jails a side branch High pressure inflation Small sized stent placed in a growing child Follow up imaging after 2 years in a patient with CoA longitudinal stent fracture New stent deployed through fractured side cell Longitudinal stent fracture with discontinuity Stent serially dilated over time to accommodate for vascular growth Layer of endothelium grows from the stent struts and narrows/obstructs the side branch orifice Figure 3: Illustrations showing side cell and longitudinal stent fractures ( in vitro and in vivo) Conclusions Stent reaches the maximum rated diameter; beyond this it cannot be further dilated Intentional fracture of stents (both longitudinal and side cell) is possible using ultra-high pressure balloons in pulmonary arteries, pulmonary veins, systemic veins, conduits and the aorta. No immediate signs of vessel wall injury was noted in any patient. In a subset of patients with follow up imaging there were no signs of vessel trauma on mid term follow up. Side cell crossed with a wire and fully expanded with a compliant balloon until a discrete circular waist is noted Ultrahigh pressure balloon of 1-2 mm larger diameter used to induce longitudinal stent fracture Balloon switched to an Ultrahigh pressure balloon of similar diameter and inflated at high pressures to induce side cell fracture Waist disappears and vessel becomes distensible References Possible to place a larger stent; Potential for vessel growth? Waist disappears Maglione J, Bergersen L, Lock JE, McElhinney DB. Ultra-high-pressure balloon angioplasty for treatment of resistant stenoses within or adjacent to previously implanted pulmonary arterial stents. Circ Cardiovasc Interv. 2009 Feb;2(1):52-8. Side branch reaches desired diameter, or additional stent may be placed through side cell Figure 1: Flow chart showing the techniques used to induce stent fracture Disclosures: none 2013 Texas Pediatric Society Electronic Poster Contest