On “Management of Significant Venous Discrepancy with Microvascular Venous Coupler” (J Reconstr Microsurgery 2003;19:377-380)

Discrepancies between recipient and donor vessel lumen caliber are the norm in microvascular surgery. Intraluminal dilatation, beveling, or “fish-mouthing” the end of the smaller vessel will compensate somewhat for any difference, to equalize a hand-sewn end-to-end microanastomosis. Sullivan and colleagues[1] have recently suggested that even extremely discrepant venous microanastomoses can be better performed using the MCA microvascular coupler, while still achieving 100 percent patency rates. Their largest vein had a diameter of 7.0 mm. Since the largest currently available coupler ring has a diameter of 3.0 mm, this represents at the least a 2.3:1 ratio with the size of the recipient vein, but their greatest difference was a startling 3.5:1!

Sullivan et al.[1] contend that “bunching of the larger vessel lumen often causes luminal invagination or constriction of the anastomoses,” if they were to be hand-sewn. Following basic laws of physics, why would this not also be true for the coupled microanastomosis? Our accompanying figure predicts the veracity of this hypothesis (Fig. [1]). The extensive experience from Bill Shaw's group[2] suggested that only minimal discrepancies were tolerable as otherwise, venous failures occurred due to flow reduction across the coupler ring. This could have presumably been due to obstruction or narrowing of the actual lumen of the larger vein due to the pleating, as we have observed (see Fig. [1]A). Unfortunately, no size ratios were documented in Shaw's cases.

Figure 1 (A) Pleats (arrows) caused after draping of this 2.5-mm vein onto 1.5-mm MCA microvascular coupler ring pins. (B) Note the greater available lumen when the same vein is switched to a 2.5-mm coupler ring.

Nevertheless, we agree that the MCA microvascular coupler is an excellent method for rapid venous microanastomosis, and is also commonly employed by us for significant venous size discrepancies with superior patency rates. This technology is especially valuable for fragile thin-walled veins, particularly as found in the head and neck region, which can tear more easily with hand-sewn techniques. However, we still have some temerity and urge caution for using this device if extreme vessel caliber discrepancies are encountered and, at least currently, continue to employ a hand-sewn end-to-side microanastomosis in these circumstances.

REFERENCES

• 1 Sullivan S K, Dellacroce F, Allen R. Management of significant venous discrepancy with microvascular venous coupler.  J Reconstr Microsurg. 2003;  19 377-380
• 2 Ahn C Y, Shaw W W, Berns S. Clinical experience with the 3M microvascular coupling anastomotic device in 100 free-tissue transfers.  Plast Reconstr Surg. 1994;  93 1481-1484