Saphenous Vein Graft Wrapping by Nitinol Mesh: A Word of Caution

We read the article by Rescigno et al, “Saphenous Vein Graft Wrapping by Nitinol Mesh: A Word of Caution,” with interest.[1] While the authors raise several excellent points, the word of caution suggested in the title may be that interpretation of the computed tomography (CT) angiogram in Nitinol-wrapped vein grafts may not be definitive. The authors note in the one angiogram performed that a vein interpreted on CT as having disease was normal. Further, when other patients with “occluded” grafts underwent stress testing, two were slightly positive, all others were negative and no further testing was done. This is inconclusive evidence for true graft occlusion. Other investigators have also noted that mesh-wrapped grafts that were interpreted to be occluded or have string sign using CT angiography were actually shown to be fully patent using ciné angiography (personal communication).

It is known that there is shadowing and scatter of CT signals with the Nitinol mesh ([Fig. 1]), which may be further obscured by the healing process or when the dye is added making the result open to misinterpretation.

Fig. 1 Computed tomography imaging of a Nitinol mesh showing scatter with blurring that may confound interpretation when coupled with dye and the healing vein itself.

Due to this effect and until more accurate CT scanning protocols can be established, we recommend that mesh-wrapped graft patency assessments be performed using ciné angiography.

Rescigno et al raise two important points with which we concur. First, including the mesh in each anastomosis makes the construction more difficult. Second, the impact of the fibrin sealant on the vein is unknown. Therefore, both factors may potentially impact outcomes. Others have had the same opinion (eSVS Mesh focus group).[2] Thus, the recommended implantation technique was recently changed such that the mesh is placed 2 to 3 mm from the cut end of the vein and not included in either proximal or distal anastomoses. Fibrin sealant is also not used to adhere the vein to the mesh.[3] Studies incorporating this new approach are ongoing.

• References

• 1 Rescigno G, Aratari C, Matteucci SM , et al. Saphenous vein graft wrapping by nitinol mesh: a word of caution. Thorac Cardiovasc Surg 2014; [epub ahead of print]
• 2 Schoettler J, Jussli-Melchers J, Grothusen C , et al. Highly flexible nitinol mesh to encase aortocoronary saphenous vein grafts: first clinical experiences and angiographic results nine months postoperatively. Interact Cardiovasc Thorac Surg 2011; 13 (4) 396-400
• 3 Emery RW, Solien E, Jamieson SW. Implantation of the eSVS Mesh. Innovations (Phila) 2012; 7 (1) 65-67

• Reply to Letter to the Editor References

• 1 Oncel D, Oncel G, Tastan A, Tamci B. Evaluation of coronary stent patency and in-stent restenosis with dual-source CT coronary angiography without heart rate control. AJR Am J Roentgenol 2008; 191 (1) 56-63
• 2 Carbone I, Francone M, Algeri E , et al. Non-invasive evaluation of coronary artery stent patency with retrospectively ECG-gated 64-slice CT angiography. Eur Radiol 2008; 18 (2) 234-243
• 3 Pugliese F, Weustink AC, Van Mieghem C , et al. Dual source coronary computed tomography angiography for detecting in-stent restenosis. Heart 2008; 94 (7) 848-854