Blood flow autoregulation in pedicled flaps

Sternocleidomastoid flap for pedicled reconstruction in head & neck surgery- revisiting the anatomy and technique

Background

Previous studies on sternocleidomastoid flaps, have defined the importance of preserving sternocleidomastoid (SCM) branch of superior thyroid artery (STA). This theory drew criticism, as this muscle is known to be a type II muscle, i.e., the muscle has one dominant pedicle (branches from the occipital artery at the superior pole) and smaller vascular pedicles entering the belly of muscle (branches from STA and thyrocervical trunk) at the middle and lower pole respectively. It was unlikely for the SCM branch of STA to supply the upper and lower thirds of the muscle. We undertook a cadaveric angiographic study to investigate distribution of STA supply to SCM muscle.

Methods

It is a cross-sectional descriptive study on 10 cadaveric SCM muscles along with ipsilateral STA which were evaluated with angiography using diatrizoate (urograffin) dye. Radiographic films were interpreted looking at the opacification of the muscle. Results were analyzed using frequency distribution and percentage.

Results

Out of ten specimens, near complete opacification was observed in eight SCM muscle specimens. While one showed poor uptake in the lower third of the muscle, the other showed poor uptake in the upper third segment of muscle.

Conclusion

Based on the above findings we suggest to further investigate sternocleidomastoid muscle as a type III flap, as the STA branch also supplies the whole muscle along with previously described pedicle from occipital artery. However, this needs to be further corroborated intra-operatively using scanning laser doppler. This also explains better survival rates of superior thyroid artery based sternomastoid flaps.

A new microsurgical research model using Thiel-embalmed arteries and comparison of two suture techniques

PURPOSE

To assess the utility of the Thiel arterial model in microsurgical research, we compared interrupted horizontal mattress (HM) sutures to simple interrupted (SI) sutures in human vessels.

METHODS

A microsurgical set-up using an operating microscope and Thiel-embalmed arteries was used to practice ten SI and HM anastomoses. Vessel patency, leak and stricture were evaluated using angiography, and vessel wall architecture was evaluated using light microscopy and scanning electron microscopy (SEM). The technique speed was also assessed.

RESULTS

We have successfully evaluated all outcomes. All anastomoses were patent. The stricture rate was higher with HM than with SI (60% vs. 35% surface area reduction). Three minor leaks occurred with HM sutures versus one with SI sutures. Edges were evenly everted without any intimal flaps with HM compared to SI. The anastomoses were performed faster using HM than SI sutures (7:58 min vs. 12:41 min, respectively).

CONCLUSION

This is the first study to evaluate the feasibility of a Thiel-embalmed artery model for research purposes. The HM microvascular suture is a promising technique that requires further in vivo validation.