**3. The role of pressure distention and wall stress during harvest**

Standard procedure in the United States is to distend the saphenous vein graft after procure‐ ment prior to myocardial implantation to ensure that all branches are ligated. The majority of the time during harvest, the vein is distended to supra-physiologic pressures [14]. While saphenous veins *in vivo* are rarely subjected to pressures greater than 60 mmHg, recorded pressure measurements during harvest easily reach 300-400 mmHg [15]. This supra-physio‐ logic pressure severely damages the endothelium and ultimately leads to premature graft closure. This high pressure is inadvertently used to overcome vasospasm as well as to ensure ligation of all side branches [16]. The pressure causes shear wall stress that denudes the protective endothelial layer (Figure 1). As a mechanism to protect itself, the endothelium releases basic fibroblast growth factors and platelet-derived growth factors [17]. Basic fibro‐ blast growth factor, a heparin-binding polypeptide that is present in the nucleus and cytoplasm of smooth muscle and endothelial cells and in the intracellular matrix, is normally a nonsecreted cell product [18]. Platelet derived growth factor is also widely acknowledged in the process of angiogenesis and most specifically in cell migration and proliferation. The release of these 2 mitogens together initiates intimal hyperplasia [17].
