Anatomic Blood Supply

Pedicled Flap

If a flap is transposed to another part of the body with the supplying vessels remaining intact it is a pedicled flap.

Pedicled flaps can be subdivided as random pattern flaps or axial pattern flaps. Random pattern flaps derive their blood supply through the cutaneous dermal-subdermal plexus. There is no defined vessel in the pedicle, but the vessels are random. The surviving length of such a flap is related to the vessels perfusion pressure and the vascular supply of the particular part of the body. The normal ratio of length to width is 1:1. However, a flap designed in the head and neck region where vascularity is optimal, length to width ratio increases up to 2.5 or 3:1 (Fig. 17-2). However, the surgeons always need to be cautious and consider risk factors for poor vascularity such as age of the patient, atherosclerosis, previous radiation, or smoking. Examples for random pattern flaps are rotational, transpositional, or advancement flaps.

Axial pattern flaps contain a direct axial vessel running in the pedicle. The length of these flaps can be as long as the supplying vessel runs in the flap. Therefore, it can be much longer. Examples of axial pattern flaps in the face are the temporal fascia flap containing the superficial temporal vessels, the forehead flap containing the supraorbital vessels, or the glabella flap containing the supratrochlear vessels.

In the head and neck, with respect to the distance between defect and donor site these pedicled flaps can be local, when the flap is designed immediately adjacent to or near the location of the defect (e.g., nasolabial flap [Fig. 17-3] and temporal muscle flap). They can be regional (trapezius, latis-simus dorsi, pectoralis major) or distant (upper arm). In the regional or distant flaps, the pedicle is usually cosmetically or functionally disturbing and needs to be divided. This is done about 3 weeks after transposition of the flap.

In small defects local flaps are the method of choice. Transposition is usually safe with regard to the vascular supply and the tissue lying adjacent to the defect matches best in texture, hair, color, and thickness. However, regional flaps from the patient's chest or back have largely been replaced by free flaps as the latter offer more flexibility with no higher complication rate.

Figure 17-2 (A) Postoperative result after excision of a SCC at the modiolus with resultant scarring and microstomia; (B and C) defect coverage with a randomized rotational flap; (D) flap in place; (E) result after 9 months.
Figure 17-2 (Continued)

Free Flap

If a flap is transplanted from another part of the body with microvascular anastomosis it is free flap. These can de classified according to the consisting tissue (cutaneous, fascial, muscular, bone) (Fig. 17-1). Free flaps have become a standard in reconstruction of the head and neck. Their variability in size, character, consistency, thickness, tissue components, and function make them the first reconstructive option in many cases particularly since a high success rate is achievable. Free tissue transfer enables selection of the most appropriate type of tissue in the required amount.

Complications of free flap reconstruction are either flap related or general medical complications.6-9 Flap-related complications can be subdivided into flap and donor site complications.

The most severe complication of a microvascular flap surgery is vascular thrombosis and flap loss. Viability of a free tissue transfer is based primarily on clinical observation, with normal capillary refill confirming vascular patency. Other methods of monitoring such as the laser Doppler and the implantable Doppler flow probes that are coupled around the vessels assist in assuring high degrees of patency. Confirmation of flap viability should be performed hourly in the postoperative period. As soon as vascular compromise is recognized,

Figure 17-3 (A) Soft tissue defect on the nose in a male patient following excision of a SCC treated with a nasolabial flap; (B) harvest of nasolabial flap; (C) rotation into the defect; (D and E) flap in place.
Figure 17-3 (Continued)

the patient should be taken back to the operating room (OR), the anastomoses explored, and vessels thrombectomized.

To avoid vascular problems, large recipient vessels in the head and neck are selected. Recipient vessels include the superficial, temporal, facial, superior thyroid, lingual, or external carotid arteries. For venous drainage, the superficial temporal, facial, and jugular veins are options.

General medical complications such as respiratory problems with pneumonia, prolonged intubation requiring tracheostomy, cardiac or thrombotic problems are not infrequent in this patient population.

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