**8.5. Breast flap**

skin is undermined over the rectus fascia to expose the muscle. Then, the rectus anterior sheet is divided and the muscle is dissected and mobilized. The distal pedicle inferior epigastric vessels are ligated and divided. The muscle is then turned to the defect. The exposed muscle

Themyocutaneous flapcanhaveaskinislandorientedverticallyalongtheusedmuscle(VRAMvertical rectus abdominis muscle flap), or horizontally, as well as perpendicular to the muscle distal to the umbilicus (TRAM-transverse rectus abdominis muscle flap). The transverse orientationpermits harvest of a larger skinpaddle.Dissection ofthe VRAMstarts with marking the skin island over the used muscle. The skin component should be placed medially near the umbilicus to include important periumbilical perforators. The skin island is cut and the skin overlying the muscle is undermined above the muscle fascia. Then, the rectus sheet is divided bilaterallyattheedgesofthemuscleandthemuscleisdissectedandmobilized.Thedistalpedicle inferiorepigastricvesselsareligatedanddivided.Theflapisthenturnedtothedefect.TheTRAM is marked transversely under the umbilicus and skin island which can involve the entire area between the umbilicus and symphysis bilaterally. The flap is dissected in the similar way as the VRAM flap, but the mobilization of the skin island continues away from the muscle pedicle crossing the midline to the contralateral side [171,185]. Care must be taken to avoid pedicle

For full length sternal defects, a combined pectoralis major and rectus abdominis flap (Pec-Rec flap) was proposed [186]. The flap is predominantly created on the left side, but can occasional‐ ly be bilateral. The skin overlying the pectoral muscle is elevated up to the mid-axillary line laterallyandfromtheclavicletotheinferiorcostallineinaverticaldirection.Thepectoralmuscle iselevatedwhilepreservingthethoracoacromialvessels.Themuscleisdetachedfromitshumeral insertion and medially from one third of the clavicle. Dissection of the flap continues distally while elevating the thoracoepigastric fascial attachments from the chest wall between the pectoralis major and the rectus abdominis. Distal to the fascia, the anterior sheet of the rectus abdominis is incisedmediallyandlaterallyandthemuscleismobilizedfromtheposteriorfascia. The muscular connections of the rectus abdominis to the distal ribs are detached as the last step of flap harvesting. The superior epigastric artery can be preserved or it can be divided close to

The latissimus dorsi flap is based on a thoracodorsal artery that has not been jeopardized by previous cardiac surgery. Moreover, a large flap can be harvested (the main surface area of

include the need for a lateral decubital position during flap harvesting that can endanger patients with large sternal bone defect and sternal instability and shoulder functional limita‐ tion followed latissimus dorsi muscle harvesting. Patients who are dependent on their

for men) [187]. The main disadvantages of this flap

and pedicle is covered either by skin suture or grafting [95].

compression passed through the subcutaneous tunnel to the sternal defect.

**8.3. Combined pectoral muscle — Rectus abdominis muscle flap**

the muscle if necessary for better medial transposition of the flap [186].

**8.4. The latissimus dorsi muscle flap**

muscle is 105 cm2 for women and 192 cm2

*8.2.2. Rectus abdominis musculocutaneous flap*

510 Artery Bypass

Obese female patients with large breasts are at higher risk of sternal dehiscence due to the infero-lateral tension of the breasts, especially on the distal third of the sternotomy [72].This instability results from the greater protrusion of the lower thorax and abdomen during respiration, greater dimensions of the lower versus the upper thorax, the concentration of forces from the attachment of the ribs, and the reduced thickness of the lower sternum [72]. Therefore a special bandage, supporting bra, or other garment is used to release the tension resulting from large breasts. The technique of covering the sternal dehiscence with a bilateral pectoral muscle advancement flap with simultaneous breast reduction has been reported [190-192]. Large breasts carry an enormous amount of relatively well vascularized tissue that can potentially be used to cover the sternal defect [193,194]. The vascular supply of the breast is basically the same as the pectoral muscle. There is, however, a unique vascular network inside the breast gland, known as Würinger´s septum. Uygur et al reported a method of covering a large distal sternum defect with bilateral fasciocutaneous V-Y flaps from the breasts [193]. These flaps were anatomically based on the Würinger´s septum [193,195]. Another method has been suggested by Hamdi et al [196]. They performed a septum-based therapeutic mammoplasty on two patients. The principle of this technique is to reduce breast mass with harvesting of a large fasciocutaneous flap from the inferomedial part of the breast

Another possibility for utilizing the breasts to cover the sternal defect is a Cyclops´ flap. In this technique the whole breast is transposed to the central or even contralateral chest defect, so that the areola is centralized. The breast flap in this case is based on the lateral and central vascular pedicles of the breast [197,198].

### **8.6. Omentum**

The greater omentum is a well-vascularized tissue with plentiful lymphatic drainage and angiogenic activity [93,98,199]. Its size can be up to 36x46 cm and is reliable to cover large defects. It is difficult, however, to predict the flap size preoperatively because the greater omentum volume has no direct correlation with the patient's habitus [200]. The omentum can be transposed to the defect in various ways such as, pedicled on both gastroepiploic arteries for defects in the distal part of sternotomy wound or mobilized on either of the gastroepiploic vessels to cover full-length sternotomy defects [201-203]. Passing the omental flap subcutane‐ ously from the upper portion of the laparotomy bears up to a 21% risk of late herniation [202], thus, a better solution seems to create the transdiaphragmatical tunnel just right of the falciform ligament [204]. The risk of abdominal cavity infection is rare [205], but the traction on the gastroepiploic artery can cause motility disturbances of the stomach and duodenum [206], and one case of fatal cecum volvulus have been reported [207]. Laparoscopic harvesting seems to be promising in reduction of access complications and pain [108,208,209].

for DSWI were enrolled until September 2011 with an overall incidence of DSWI of 1.36%. The results of 28 patients (March 2002-June 2004) primarily treated with closed chest irrigation using diluted iodine solution were compared with 76 patients (September 2004 to September 2009) treated with NPWT (VAC ATS™, KCI, St. Antonio, USA). A standardized protocol for first-line application of NPWT is depicted in Figure 1. Six patients from the interim period (June to September 2004) when closed irrigation and NPWT were combined were excluded from the analysis. Both groups had comparable demographic and perioperative characteris‐ tics, however, the NPWT arm had an insignificant trend towards advanced age, higher logistic EUROSCORE, more complex primary cardiac surgery. No difference in the rate of causative agent was found, with SA and CONS identified in almost 70% of cases. Escherichia coli (5.8%) and Pseudomonas species (7.2%) as leading Gram negative strains were cultivated. The time to presentation of DSWI was insignificant between groups (17.5±15.0 vs. 13.8±16.3, p=0.55) as well as readmission for late clinical presentation of DSWI (38.6% vs. 50%, p=0.12). Although the overall length of DSWI therapy was comparable (14.3±11.9 vs. 14.9±7.9 days, p=0.82), NPWT required more dressing changes (5.4±2.3 vs. 1.8±1.2, p<0.001), but was associated with substantially lower failure of primary therapy (5.1 vs. 39.2%, p<0.01) with closed chest irrigation. In-ICU stay was significantly shorter in the NPWT group (209.6±331.3 vs. 516.1±449.5 hours, p<0.001), nevertheless, shortened in-hospital stay (40.2±16.3 vs. 48.8±29.2 days, p=0.16) was insignificant in this group. Addressing mortality, 30-day and 1-year mortality was considerably lower in the NPWT arm (3.9 vs. 21.4%, p<0.05, 15.8 vs. 39.2%, p<0.05, respectively). A Kaplan-Meier 1 year-survival analysis is shown in Figure 2. The risk of major bleeding complications was comparable between groups, with 2 patients (3.6%) from the closed chest irrigation group having erosion of venous bypass graft and right ventricle (RV), and 3 patients (3.9%) from the NPWT group, including 1 debridement-related and 2 spontaneous injuries of the RV. Employment of local and advancement flaps for covering of residual defects was higher in the NPWT groups (65.7 vs. 17.8%, p<0.01). Our experience showed that NPWT is effective in the treatment of DSWI, compared with closed chest irrigation, leading to lower failure of primary therapy, ICU stay, and better short- and midsurvival of patients. We did not prove NPWT influenced length of in-hospital stay or risk of major bleeding, however, residual defects required more complex approach to assure sternal

Current Challenges in the Treatment of Deep Sternal Wound Infection Following Cardiac Surgery

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stability and covering defects [119,130].

**9.2. Sternal stabilization and management of residual bone defects**

Non-complicated sternal dehiscence following DSWI that is not associated with considerable bone loss can be stabilized with transverse titanium plates (Titanium Sternal Fixation system™, Synthes, Switzerland) at our department. Plates are applied on the anterior surface of the ribcage to achieve sufficient stability of the chest wall while minimizing the risk of an iatrogenic injury to the heart. From January 2008 to September 2012 we performed 31 sternal wall reconstructions using the Titanium Sternal Fixation system™. In four cases, osteosynthesis was applied to treat a sterile mechanical dehiscence of the median sternotomy, while 27 other chest osteosyntheses were performed after DSWI when wound bed decontamination was achieved with NPWT. In the postoperative period, 2 patients (7.4%) needed to be operatively revised due to bleeding from pectoral flap advancement; in 3 cases (11.1%) the plates needed

#### **8.7. Microsurgical flaps**

Microsurgical free flaps can be used to cover sternal defects in particular situations. This technique, due to its duration and technical complexity, should serve as a last treatment option. The use of the tensor fascia lata myocutaneous flap, rectus abdominis myocutaneous flap and deep inferior epigastric artery fasciocutaneous flap for this indication have been reported [210]. As a donor vessel, the thoracoacromial, internal thoracic or cervical vessels can be used. The cephalic vein attached to the thoracoacromial or cervical arteries, can be used for lengthening the donor vessel (arterio-venous loop) [210,211].

#### **8.8. Specifics of care after flap surgery in cardiac surgery**

There are special requirements for care after flap surgery. In general, it is important to protect the blood circulation within the flap, maintaining both general and local hemodynamics. Vascular spasm must be prevented by using vasodilator drugs if possible. The elevated and transposed flap usually loses most of its physiological blood and lymphatic network and is dependent only on a small part of it, so varying degrees of edema are usually present. Large swelling of the tissue compresses the capillaries and decreases the blood flow in the flap, increasing the tension on the suture. Corticosteroids are used to prevent swelling for several days in most flap surgeries unless serious contraindications are present. The flap must be kept from topical pressure, particularly in places of passing vascular pedicle and in peripheral parts of the flap because of limited vascular competence. Undoubtedly, changes in body position influence the blood supply of the flap. Furthermore, stretching of the arms causes increased tension on the medial sternal suture. In the case of the pectoral and latissimus dorsi flap, the use of muscles of the shoulder girdle should be avoided. When using the rectus abdominis flap, the abdominal wall must be relaxed and supported with bandages for several weeks to prevent hernia formation. Finally, nutritional support with enteral feeding is essential for successful healing.
