Page 12 - Journal of Structural Heart Disease Volume 3, Issue 6

Original Research Article 168
Figure 2. Pre-stenting technique. Panel A. Angiogram of the abdominal aorta with a 4-mm Cook Formula 418 stent implanted 5 months prior (stent diameter: 7.3 mm). Panel B. Implantation and anchoring of a Palmaz Genesis 1910 B stent mounted on a 10- mm Power ex balloon. Panel C. Intentional fracture of the previously implanted Cook stent with simultaneous dilation of the newly implanted Palmaz Genesis stent using an ultra-high-pressure 12-mm Atlas balloon. Panel D. Radiograph showing the integrity and position of the newly implanted Palmaz Genesis stent inside the previously implanted Cook stent. Panel E. Angiogram showing vessel patency and minimal in-stent restenosis at the edges of the Palmaz Genesis stent 2 months after implantation (stent diameter: 9.9 mm). Black arrows indicate the edges of the Palmaz Genesis stent.
erinary pathologist, who assessed the stented blood vessel and adjacent areas for evidence of macroscop- ic tissue damage such as bleeding, contusion, rup- ture, and scarring. Major body systems including the brain, thoracic cavity viscera, peritoneal viscera, and hind limb muscles were examined grossly. Hind limb muscles were sectioned serially. In addition to stent- ed regions of the aorta, a standard list of 33 tissues, as well as any grossly visible or suspected lesions, were collected for histopathology. Five muscle groups from each hind limb, lymph nodes regional to the hind limbs and descending aorta, and multiple sec- tions of brain, lung, each kidney, liver, heart, spleen, and spinal cord were microscopically examined for any embolic lesion or stent fragment displacement.
Intentional Stent Fracture and Pre-Stenting Techniques
Serial dilation of small-diameter pre-mounted stents with intentional stent fracture and pre-stent- ing was feasible in a growing piglet model that mim- ics physiologic changes occurring in the vasculature of growing children. Small-diameter pre-mounted stents were successfully implanted in small vessels (Figure 2A). As expected, the patency of the growing blood vessel at the level of the stent was reduced by the previously implanted stents (Figure 2A); howev- er, the vessel above and below the stent grew to al- most double the original size of the vessel that held
the original stent. Low-pressure balloons did not fully dilate and fracture the stents (Figure 2B), but ultra-high-pressure balloons achieved intentional stent fracture and re-dilation of previously implant- ed stents (Figure 2C). Stent dilation was performed in increments, and fracture occurred at the previously noted fracture diameter determined by bench test- ing [4]. In the single stent group, the stents were thin- ner and more di cult to visualize in the older pigs, so more atmospheres were used to ensure their break- age.
Radiographic, Angiographic, Gross Inspection, X-ray, Computed Tomographic, and Histopathologic Evalua- tion
Radiographic images and angiograms were ob- tained during all catheterization procedures. After euthanasia, necropsy was performed for gross in- spection, histologic, and radiographic evaluation. The stented vessels were ushed with physiological saline for approximately 10 min followed by perfusion of Prefer xative for 15 min prior to excision. Vessel di- ameter was measured using angiograms, and vessel luminal area was assessed using histologic samples.
Radiography. High-resolution radiography and micro computed tomography (CT) were performed on all stents after explant. High-resolution radiog- raphy was performed using a Kubtec Xpert 80-L w/
Journal of Structural Heart Disease, December 2017
Volume 3, Issue 6:165-175