Atypical arteriole anastomoses for fingertip replantations under digital block☆

Case reports 

Case 1: arteriole venular anastomosis and arteriole graft for venous drainage 

A 47-year-old man sustained complete amputation of the left middle finger at the level of the nail bed. Replantation was performed under digital block. After exploring the defect, it was found that the digital arterial arch was preserved and four arterioles derived from the arch were transected. Therefore, two arterioles (terminal branch of digital artery, 0.3mm each) in the proximal finger were anastomosed to the distal arteriole and the palmar subdermal venule in the volar aspect. The other distal subdermal venule (0.3mm) was joined to the proximal subdermal venule in the ulnar aspect with an arteriole graft, which was one of the proximal four arterioles in the proximal stump. All vascular anastomoses were performed with 11/0 nylon with a 50-micron needle.

Postoperatively, the fingertip survived completely without any venous congestion or arterial insufficiency (Fig. 1).

View Large Image Download to PowerPoint

Figure 1 (A) Case 1. A 47-year-old man with the fingertip amputation of the left middle finger. Left: dorsal view. Right: volar view. (B) Left: preoperative schema (volar aspect). All the terminal arterioles and venules were completely transected at the distal end of the digital arch. A, distal side of the anastomosed terminal arteriole; V1, distal terminal venule used for arteriovenous anastomosis; G, terminal arteriole used as a graft for venous drainage between both venules (V2, V3). Right: after the completion of vascular anastomoses. The terminal arteriole (G) was grafted for venous drainage (V2, V3). (C) Left and Right: 2 months after surgery.

Case 2: reverse flow of arteriole to venule and delayed venous drainage 

A 28-year-old man sustained traumatic amputation of the left little finger at the level of distal interphalangeal joint due to strong avulsion. The finger was attached only by the flexor tendon and the ulnar digital nerve, and the finger had no blood flow.

Replantation was performed under a digital block. As the ulnar digital artery was severely damaged as well as the ulnar digital nerve, it could not be used as a feeder for arterial inflow of the replanted finger. The radial digital artery was obstructed in a long length by thrombosis. Therefore, the tiny branch (arteriole, 0.3mm in diameter) of the radial digital artery was transected to anastomose the distal subcutaneous venule as a source of reverse arterial inflow. However, as there was very little arterial inflow, little dermal bleeding of the replanted finger was detected after vascular anastomosis using 11/0 nylon with a 50-micron needle. Unfortunately, no other venule bleeding could be detected in the replanted finger. Therefore, no venous anastomosis could be achieved in the primary surgery. The replanted finger was pale and there was little bleeding with a pinprick test.

The next day after the primary replantation, the replanted finger was congestive and re-exploration was carried out under a digital block. As dilated subdermal venules were easily detected in the congestive distal replanted finger, venous drainage with a vein graft was achieved between the distal and proximal subdermal venules on the dorsal aspect of the finger. The vein graft (0.5mm in diameter and 10mm in length) was obtained from the dorsal foot under local anaesthesia.

Postoperatively, venous congestion disappeared, and the finger survived completely (Fig. 2).

View Large Image Download to PowerPoint

Figure 2 (A) Case 2. A 28-year-old man with fingertip amputation of the left little finger. Left: dorsal view. Middle: volar view; Right: preoperative X-ray film. (B) The schema of primary surgery under local anaesthesia. Left and Centre (volar aspect): reverse flow of transected tiny arteriole (C) of the thrombosed digital artery (B) was used to revascularise the replanted fingertip. D, subdermal venule. Right (dorsal aspect): delayed venous drainage using a venular graft was effective by the next day; E, cutaneous venule. (C) Second day, venous congestion (left) was repaired with delayed venular drainage (right). (D) Left and Right: 2 months after surgery.

Discussion 

With the development of supermicrosurgery, we can now anastomose 0.3-mm-calibre vessels, and more distal fingertip replantations at the arteriole level, distal from the digital artery arch, have been indicated. Replantation at this level is not without difficulties, however, because there are often problems of weak arteriole inflow, technically difficult vascular anastomosis, and postoperative thrombosis of the digital arterioles and venules.

Based on our case 1, fingertip replantation was successfully carried out with arteriole and arteriovenular anastomoses, as well as arteriole and venular grafts to reconnect subdermal venules of 0.3mm for establishment of venous drainage. The arteriole graft was obtained from the same fingertip defect under digital block. This is a new ideal candidate for vascular graft because there is no need for additional local anaesthesia.

Based on our case 2, it was proved that anastomosis between a tiny arteriole and venule (arteriole venular anastomosis) is very effective. An arteriovenous anastomosis between a tiny digital artery and the subdermal venules to establish an arterial and venous drainage system is important for fingertip replantations.4 We have already reported that arteriovenous anastomosis is very effective for distal phalangeal replantations,4 because it is thought that there are no valves of the venules in the fingertip regions. In addition, as an atypical application of vascular anastomosis, reverse arteriole flow is one method in the case of main digital artery embolisation.

With regard to delayed venous drainage for repair of venous congestion as in case 2, we recently reported that delayed venous drainage using subdermal venular anastomosis with vein graft proved to be very effective, because total success rate was increased from 50% (without delayed drainage) to 81.3% (with delayed drainage).7 The reason for this high success rate is that expanded venules in the congestive fingers became larger and had strong back flow (sometimes they had pulsative bleeding at the secondary operation).

Other alternatives are to allow bleeding from the amputated part as a surgical5, 8, 9 or medical leech.8, 10 These conservative techniques have been less than satisfying and the latter leeches have possible complications such as blood loss8 and significant infections (7–20% of cases of leech application for venous outflow problems8).

Finally, we are now in a new stage of supermicrosurgical vascular anastomoses for 0.3-mm-calibre vessels, and the arterioles and venules could be recipient vessels for tissue transfers for finger defects. We also believe that fingertip replantations can be easily performed under digital block, with no need for axillary block or general anaesthesia. In future, new tissue transfers with supermicrosurgery will be possible under local anaesthesia.