Patency, flow, and endothelialization of the sutureless Excimer Laser Assisted Non-occlusive Anastomosis (ELANA) technique in a pig model

Laboratory investigation

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Object

The purpose of this study was to assess flow, patency, and endothelialization of bypasses created with the sutureless Excimer Laser Assisted Non-occlusive Anastomosis (SELANA) technique in a pig model.

Methods

In 38 pigs, a bypass was made on the left common carotid artery (CCA), using the right CCA as a graft, with 2 SELANAs. Bypass flow was measured using single-vessel flowmetry. The pigs were randomly assigned to 1 of 12 survival groups (1, 2, 3, 4, 5, 6, 7, and 10 days; 2 and 3 weeks; and 3 and 6 months). One extra animal underwent the procedure and then was killed after 1 hour of bypass patency to serve as a control. Angiography was performed just before the animals were killed, to assess bypass patency. Scanning electron microscopy and histological studies were used to evaluate the anastomoses after planned death.

Results

The mean SELANA bypass flow was not significantly different from the mean flow in the earlier ELANA (Excimer Laser Assisted Non-occlusive Anastomosis) pig study at opening and follow-up. Overall SELANA bypass patency (87%) was not significantly different from the ELANA patency of 86% in the earlier study. Complete SELANA endothelialization was observed after 2–3 weeks, compared with 2 weeks in the earlier ELANA study.

Conclusions

The SELANA technique is not inferior to the current ELANA technique regarding flow, patency, and endothelialization. A pilot study in patients is a logical next step.

Abbreviations used in this paper: BA = basilar artery; CCA = common carotid artery; ELANA = Excimer Laser Assisted Nonocclusive Anastomosis; ICA = internal carotid artery; MCA = middle cerebral artery; PCA = posterior cerebral artery; SELANA = sutureless ELANA; SEM = scanning electron microscopy.

Article Information

Address correspondence to: T. P. C. van Doormaal, M.D., Ph.D., Department of Neurosurgery, Rudolf Magnus Institute of Neuroscience, G.03.124, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. email: T.P.C.vandoormaal@umcutrecht.nl.

Please include this information when citing this paper: published online July 22, 2011; DOI: 10.3171/2011.6.JNS101491.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Schematics showing the SELANA bypass procedure. A: The pig schematically drawn in supine position with location of the incision (dotted line) and of the 2 CCAs. B: The SELANA device was first slid over the removed right CCA, a small tail was cut at the back, and was flipped between the back of the pins. At the back, the small tail was attached to the large front flapped tail with 2 Prolene sutures (8-0) above the ring and pins, not fully penetrating the arterial wall. C: The large front tail was flipped anteriorly between the pins and the ring. It was attached at the anterior side to the arterial wall with 1 stitch of 8-0 Prolene, not fully penetrating the arterial wall. D: The SELANA device, including the bypass graft, is slid into the left CCA. The pins puncture the wall and are first positioned under the vessel wall. By then tilting it and subsequently transposing the device forward, the straight part of the pins slide inside out again while the circumferential part of the pins “clicks” under the recipient wall. E: The insertion of the SELANA devices was in the direction of the final vessel occlusion. F: The SELANA anastomoses were sealed with TachoSil. G: The anastomoses were opened using the laser, with the aid of an ELANA 2.0 catheter. H: End-to-end anastomosis. The recipient CCA remains patent during this procedure. I: Bypass in situ with definitive occlusion of the recipient CCA.

  • View in gallery

    Photographs of the SELANA device. A: The first SELANA design, with straight pins. B: The new SELANA design, with curved pins. This results in a better “flush” position of the SELANA anastomoses. C: Finished SELANA bypass, with definitive hemoclips put on the recipient CCA between the SELANA anastomoses. The CCA flow before the laser was used was measured as 277 ml/min. Flow through the bypass was measured as 183 ml/min. The blue device around the distal CCA is the single-vessel flowmeter.

  • View in gallery

    Postoperative angiograms obtained in pig no. 10. A: Control angiogram obtained at 3 weeks. The arrow indicates the back of the proximal SELANA device. Flow at opening was 135 ml/min. B: Angiogram obtained just before the animal was killed at 6 months. Flow at planned death was 245 ml/min. Arterial remodeling pushed the SELANA device upward. The arrow indicates the back of the proximal SELANA device. The bypass graft increased in size, causing a relative constriction at the level of the SELANA device.

  • View in gallery

    Arterial remodeling of the SELANA and ELANA anastomosis. A: The ELANA anastomosis, 3-month survival subgroup. The arrow points out the newly formed arterial wall under the ELANA ring. The ring is angulated approximately 20° from the recipient artery, whereas it is still perpendicular to the bypass graft. (Adapted with permission from Streefkerk HJ, Kleinveld S, Koedam EL, Bulder MM, Meelduk HD, Verdaasdonk RM, et al: Long-term reendothelialization of excimer laser-assisted nonocclusive anastomoses compared with conventionally sutured anastomoses in pigs. J Neurosurg 103:328–336, 2005.) B: The SELANA anastomosis, 3-month survival subgroup. The arrow points out the newly formed arterial wall under the SELANA ring. The device is angulated approximately 30° compared with the recipient artery, and is perpendicular to the bypass graft.

  • View in gallery

    Photographs of anastomoses after planned death (view from inside). A: Acute sample (obtained at 1 hour of survival). No endothelialization of the pins, laser edge, or edge between the bypass graft and recipient vessel is seen. B: At 10 days of survival, endothelialization is starting over the pins. The laser edge migrated backward. C: At 3 weeks of survival, there is complete endothelialization. The laser edge is totally retracted and endothelialized, and the endothelialized pins are still slightly visible. D: At 6 months of survival, there is complete endothelialization. Arterial remodeling under the ring is present, and the contours of the pin are no longer visible.

  • View in gallery

    Series of SEM studies. The anastomosis is cut in 2 parts on the longitudinal axis. A schematic drawing indicating the location of the SEM picture (box) is presented on the left of each picture. A: Acute sample (obtained at 1 hour of survival) showing clear demarcation between (from upper to lower panels) bypass graft, laser edge, pin, and recipient artery. The endothelial cell layers of the donor and recipient artery are completely intact. The different layers of the recipient artery (intima, media, and adventitia) can be clearly distinguished on the laser edge, which is covered by platelet aggregates and fibrin deposits. On the pin only a few thrombocytes are attached. B: At 10 days of survival. The laser edge is retracted and endothelialized. The border between the donor artery and recipient is still visible. Endothelium has started to grow over the pin, preceded by activated thrombocytes and fibrin, which adhere to the smooth surface of the pin (see detail on far right, with precursor cells attached to the pin surface). C: At 3 weeks of survival. The SELANA device is completely endothelialized, and is visible as a single layer. D: At 6 months of survival. The endothelial layer over the device is thinner because the anastomosis has expanded within and ultimately slightly over the device. However, no spots without endothelium are visible.

  • View in gallery

    Histological studies. The anastomosis was embedded in plastic, cut with a diamond saw perpendicular to the recipient CCA, and stained with H & E. A: Specimen obtained at 10 days. The upper black spot is the ring, and the lower spot is the circumferential part of the pin, which is already covered by endothelium. However, the edge between recipient and donor artery is not (arrow). B: Specimen obtained at 3 weeks. A new arterial wall covers the ring and pin (arrow). Two white blocks appear on the left because the metal was washed away during preparation. The black bubbles are artifacts from the high heat resulting from cutting with the saw. C: Specimen obtained at 3 weeks. The new arterial layer is covering the edge between the recipient and donor artery (arrow).

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