Discussion

Separation of any fistulous tract requires tract isolation, division, interposition of vascular tissue and tension-free layered closure of the lining elements. These steps are critical to prevent a fibrotic scar around the site, and thus avoid recurrence.^{Reference Murono, Ishikawa, Nakanishi, Endo, Kondo and Wakisaka8}

Closure of a tracheoesophageal fistula is challenging, particularly in an irradiated field.^{Reference Marsden, Shukla and Grinsell9} A thin and pliable flap is necessary given the tubular configuration of the pharynx and trachea, and the narrow access of this anatomical region, which is limited by the sternum and clavicles. Historically, muscle and myocutaneous flaps – the pectoralis major and latissimus dorsi – were used for resurfacing lower face and neck defects. However, these were bulky, with the potential to cause tracheostomal obstruction and added donor site functional loss.^{Reference Schellekens, Hage, Paes and Kon10}

As fasciocutaneous composite tissue, the internal mammary artery perforator flap fulfils these criteria and has become our first choice in this situation. It may be used to close the most commonly found tracheoesophageal fistula, as its superior limit is the lower third of the face.

The mammary artery pectoral flap, originally described by von Joseph in 1931,^{Reference Joseph11} was based on the third and fourth anterior intercostal perforators. This was followed by Conley in 1960, who described the anterior chest flap, with the medial pedicle running infero-obliquely from the sternum, based on the internal mammary perforators.^{Reference Conley12} Bakamjian, in 1965, described ‘rotating an oblong rectangular flap of skin from the pectoral region into the neck and inverting it to form a hollow epidermal tube based on the perforating branches of internal mammary vessels’ for pharyngoesophageal reconstruction.^{Reference Bakamjian13} He called it the deltopectoral flap; however, he did not visualise the perforators. Additionally, the donor site required skin graft for closure. With the advent of microsurgical technology and its widespread use, this chest wall flap fell out of favour, only to be used as a salvage option.

The concept of perforasomes, introduced in 1989 by Koshima and Soeda, ushered an era of defining composite tissues based on named and unnamed perforators.^{Reference Koshima and Soeda6} This led to the description of an internal mammary artery perforator island flap for anterior neck reconstruction by Yu et al. in 2006,^{Reference Yu, Roblin and Chevray14} and Vesely et al. in 2007.^{Reference Vesely, Murray, Novak, Gullane and Neligan7} We use it as a first choice in tracheoesophageal fistula closure, in post-radiated laryngeal carcinoma patients.

The angiosomal territory of the internal mammary artery has been well documented in studies on living patients and cadavers.^{Reference Schellekens, Paes, Hage, van der Wal, Bleys and Kon15} It encompasses an area from the clavicle to the level of the ninth rib, and from the midline to the anterior axillary line, with a variable area in the superolateral region being occupied by the thoracoacromial angiosome. The cutaneous perforators are located 13–14 mm from the lateral sternal border, with diameters ranging from 1 to 1.5 mm. They pass through the medial fibres of the pectoralis major. The perforating vessels are usually found in the first five intercostal spaces, but are more frequently found in the second (68.9 per cent) and third (27.2 per cent) intercostal spaces. The second perforator was most often the largest in both sexes, being generally greater than 0.8 mm. In females, the third and fourth perforators also tend to be large, as they contribute to the arterial supply of the breast.^{Reference Vesely, Murray, Novak, Gullane and Neligan7,Reference Schellekens, Paes, Hage, van der Wal, Bleys and Kon15} However, the internal mammary perforators have been shown to vary in size and dominance between patients and chest side. Palmer and Taylor found that there was a single dominant perforator in 85 per cent of cases, which was at least twice the size of any other perforator, while in the other 15 per cent there was co-dominance, with two perforators being of equal size. The diameter of the dominant perforator is 0.5–1.2 mm, and that of the accompanying vein is 1.5–3.2 mm.^{Reference Palmer and Taylor16}

Mirghani et al., in their retrospective 2013 study of 12 internal mammary artery perforator flaps, described removing the second or third rib cartilage immediately superior to the selected internal mammary artery perforator for enhanced exposure.^{Reference Mirghani, Leymarie, Amen, Qassemyar, Leclère and Kolb17} They then ligated the internal mammary artery and vein distal to the origin of the selected internal mammary artery perforator, to increase the total length of the flap pedicle and improve its arc of rotation.^{Reference Mirghani, Leymarie, Amen, Qassemyar, Leclère and Kolb17} In our series, sacrificing the distal inferior mesenteric artery vessels and costochondral resection has not been necessary. Dissecting the pedicle through its intramuscular course alone, enabled adequate reach.

The internal mammary artery perforator flap has several advantages over the deltopectoral flap: the ability to be islanded, the avoidance of ‘dog-ear formation’ and primary closure of the donor site. Pedicle twisting or kinking has not been reported.

Resection of costal cartilage to gain pedicle length has been reported to cause pneumothorax rarely.^{Reference Schellekens, Hage, Paes and Kon10} Although issues with flap venous congestion have been described, we did not encounter it. There were no complications of flap retraction, suture line dehiscence or donor site scar hypertrophy.

This technique may similarly be employed for the management of tracheoesophageal fistulae of other aetiology – like trauma or Crohn's disease – as long as the pedicle and flap are outside the zone of injury. However, our experience is limited to radiated patients with laryngeal carcinoma.