The median sternotomy is the most common surgical approach for cardiac surgery. It is widely used because of its sufficient exposure and convenient operation. However, once the median sternotomy is infected, especially the deep incision infection, treatment is very difficult. These increase suffering of patient, prolong hospital stays, and increase treatment costs. It is difficult to cure after debridement treatment, and the incision infection that has not healed eventually develops into DSWI. The incidence of this disease is between 0.4% and 5.0%. There are many causes of deep sternal incision infection[11, 12], such as diabetes, obesity, advanced age, chronic obstructive pulmonary disease, long-term heavy smoking, chronic renal failure, immune function, low heart function, long operation time, excessive bleeding, and malnutrition.
At present, the main treatment of DSWI is the application of tissue flap transfer after debridement. After a lot of clinical experience, the pectoralis major muscle flap (PMMF) has great advantages. The main advantages of the PMMF: (1) The pectoralis major muscle is close to the sternum, easy to dissociate, no need for another incision. The flap size can be adjusted according to the size of the wound; (2) The blood supply of the pectoralis major muscle is rich, such as the intercostal artery. Therefore, the PMMF is the main treatment for tissue flap repair now. Among them, PMMTF is the main method. However, this method requires cutting off the lateral muscle fibers of the pectoralis major, which affects the function of the upper limbs. This method needs to cut or damage the intercostal perforating vessels and the thoracodorsal peak arteries, which will affect the blood supply of the muscle flaps, because the perforating vessels and the thoracic and thoracic peak arteries are important blood supply sources for the pectoralis major.
The bilateral-pectoral major muscle advancement flap was used in our team to treat chronic sternal osteomyelitis. By the method, the muscle fibers on the outer side of the pectoralis major muscle can be retained, which preserves the function of the pectoralis major muscle and thus does not affect the function of the upper limbs. During the operation, only the starting position of the pectoralis major muscle is changed, and the upper limbs function is not affected at all. According to the size and location of the defect, the trauma can be reduced and the time of operation can be shortened. Because the starting point of the pectoralis major muscle (the sternum and part of the rib) is cut off, the bilateral pectoralis major muscle flap is advanced to the midline, which can well protect the intercostal artery perforator and the thoracic and shoulder arteries to prevent muscle ischemia.
The theory of wet healing is a new concept in recent years, which can provide a better outcome, less pain and less scar formation. VAC can provide a moist environment for wounds, which is a great improvement in wound healing treatment. The treatment of VAC not only promotes vascular proliferation, but also promotes differentiation of cells around the new capillary. For soft tissue defects and dead space, VAC can gradually achieve the purpose of eliminating dead space. Continuous attraction should be avoided, and continued attraction can lead to poor local blood circulation and chronic ischemia. Intermittent attraction can cause reactive hyperemia and increase blood flow into the wound. When the negative pressure is stopped, the poorly perfused tissue is reactively hyperemic, increasing the oxygen and nutrients of the wound and increasing the waste removal. In short, the main reasons for VAC can promote local blood flow, reduce bacterial growth, increase the growth rate of wound granulation tissue, shrink wounds, and promote epithelial growth.
To summarize the experience of using bilateral-pectoral major muscle advancement flap combined with VAC for DSWI. The following points are necessary: (1) Thorough debridement. Remove the suture, dead bone, necrotic tissue and granulation tissue in the lesion. It is important to eliminate the source of infection completely, and soak with hydrogen peroxide and iodophor solution to make the surgical area relatively sterile. After debridement, DSWI is used; (2) DSWI is rationally used. DSWI can fill the incision, pressure the sternum and reduce the tension of the flap. (3) Apply the appropriate size of the PMMF to fill the wound. Do not leave a dead space to prevent re-infection. (4) Internal fixation that does not affect the stability of the sternum is removed,such as ligation wire. The internal fixture that affects the stability of the sternum is temporarily reserved for secondary surgery. According to the stability of the sternum, the second surgery determines whether the fixture is removed. The stability of the sternum after VAC is generally increased. The loosened wire is fixed, and the wire and sternum claws which have no fixed function are removed. (5) Bilateral pectoralis major muscles and wounds should completely stop bleeding. There is no blood and effusion in the wound to prevent re-infection.
This study demonstrates that bilateral-pectoral major muscle advancement flap combined with VAC is effective in the treatment of DSWI. The recurrence rate is low, the operation procedure is simple, and there is no need to increase the surgical incision. Patients are more likely to undergo this type of surgery. It is easier for clinicians to master. Satisfactory long-term results, and almost no complications.