Biomechanical evaluation of different methods for securing cellophane bands for portosystemic shunt attenuation and factors that affect construct failure

Abstract

Objectives: To secure a cellophane band around a vein with either three or four layers with a polymer or titanium hemostatic clip of either medium or medium-large size, at 25% or 50% vessel attenuation, and observe the conditions under which the construct is more likely to fail and the pressure at failure. Study design: Ex-vivo mechanical evaluation Methods: Cellophane bands composed of three or four layers were applied around a cadaveric external jugular vein (EJV) to create 25% or 50% attenuation. These bands were secured with Polymer Locking Ligation Clip (PLLC) medium/medium-large, or Titanium Ligation Clip (TLC) medium/medium-large. Sterile saline 0.9% was instilled into the lumen of the EJV until a pressure of 100mmHg was reached. Failure mechanism and luminal pressure at failure were compared between groups. Results: Medium clips were significantly more likely to fail than medium-large clips (P= <0.001). Three-layer cellophane bands were significantly more likely to fail than four-layer bands (P=0.003). Failure also occurred at significantly lower pressures with a 3-layered cellophane band compared to a four-layered band (P=0.027). There was no significant difference between the failure rate of the cellophane band construct secured with PLLC or TLC, (P = 0.635) or with 25% vs 50% attenuation (P=0.780). The four-layer cellophane band, was 4.1 times less likely to fail (CI 1.6-10.2) than the three-layer cellophane band. Conclusion and clinical relevance: One, medium sized clip either PLLC or TLC is sufficient to withstand physiological forces when securing a cellophane band around a vein at up to 50% attenuation. A cellophane band with four layers is less likely to result in clip slippage and failure compared to a cellophane band with three layers. The recommendation would be to secure a four-layer cellophane band with a medium sized PLLC if follow-up CT scans may be required.