Rectus Abdominis Flap for Thoracic Reconstruction

Maureen Beederman

David H. Song

DEFINITION

Chest wall defects can involve the skin, subcutaneous tissue, muscle, rib, and underlying thoracic viscera.
The rectus abdominis muscle flap (with or without overlying skin) can be used for chest wall defects and is especially useful for anterior, lower sternal, and parasternal defects.¹
- A vertical rectus abdominis myocutaneous (VRAM) flap contains both rectus abdominis muscle and overlying skin and subcutaneous tissue, supplied by a pedicle and its musculocutaneous perforators, with skin paddle oriented in a vertical direction.
- A transverse rectus abdominis myocutaneous (TRAM) flap contains both rectus abdominis muscle and overlying skin and subcutaneous tissue, supplied by a pedicle and its musculocutaneous perforators, with skin paddle oriented in a horizontal direction.
Rectus abdominis flaps can be used to fill a large amount of dead space or to cover prosthetic materials used for chest wall stabilization, such as methyl methacrylate, mesh, or titanium plates.

ANATOMY

The rectus abdominis muscle is a Mathes-Nahai type III muscle with two dominant vascular pedicles: the superior epigastric artery and inferior epigastric artery.
- The superior epigastric artery is a continuation of the distal portion of the internal mammary artery (IMA), which originally arises from the subclavian artery.
- The inferior epigastric artery arises from the external iliac artery.
- The rectus abdominis muscle has a predictable blood supply, making it a dependable option for reconstruction.
Secondary blood supply also arises from intercostal arteries.
Rectus abdominis muscle consists of two muscle bellies separated by the linea alba.
- Each muscle is enclosed in fascia, which is formed from the aponeurosis of the external oblique, internal oblique, and transversus abdominis muscles.
- Rectus abdominis muscle origin: xiphoid and 5th to 8th costal cartilages
- Rectus abdominis muscle insertion: pubic symphysis
The rectus abdominis muscle is thick, bulky, and durable and is good for filling dead space.
One can raise the muscle in a vertical (VRAM) or transverse (TRAM) manner, depending on the size and orientation of the defect.

PATHOGENESIS

Chest wall defects can occur as a result of trauma, tumor resection, infection, congenital disorders, or radiation-induced necrosis.
Infectious sources include empyema, bronchopleural fistula, or mediastinitis after cardiothoracic surgery.
- Sternal wound infection risk factors include obesity, diabetes, COPD, and bilateral harvest of IMAs during prior cardiothoracic surgery (compromising blood supply to the sternum and overlying tissues).²

PATIENT HISTORY AND PHYSICAL FINDINGS

Patient history is important to consider when planning for chest wall reconstruction, as it will affect the reconstructive decision-making and options.
- Consider previous attempts at chest wall closure and reconstruction, specifically if other local flaps have been used, including latissimus dorsi, pectoralis major, or omental flap.
- Significant prior abdominal surgery, including autologous breast reconstruction or abdominoplasty, which could affect blood supply to the rectus abdominis muscle
- One or both IMAs may have been harvested for prior cardiac surgery, which may adversely affect the superior epigastric artery blood supply to rectus abdominis musculature and need to be closely examined. However, owing to extensive intercostal collaterals, mostly a superiorly based flap is viable.
- The presence of an ostomy or urostomy can potentially affect utility of rectus abdominis muscle.
- A history of diabetes or history of smoking can affect small vessels and compromise blood supply to the skin of VRAM/TRAM flaps.
- Other risk factors that can compromise reconstruction include obesity, malnutrition, older age, steroid use, and other comorbidities.
Discussion of future treatment planning with thoracic surgeon
- Determine whether the patient has had or will need to undergo future radiation therapy, as this will affect local tissue quality and flap options.
Physical examination
- Assess chest wall space requiring reconstruction, including the presence of mediastinitis or other localized infections, bronchopleural fistula, and exposure of vital organs.
- Determine whether bony reconstruction is required.
  - Skeletal support is most often required for lateral and posterolateral wall defects.¹
  - Number of ribs removed and history of chest wall radiation can affect the need for structural support.

IMAGING

Imaging may not be required for all patients.
CT of the chest and abdomen may be done to assess extent of tumor, invasion of surrounding structures, amount of dead space, and possible fluid collections or infection.
Assess abdominal wall integrity, including the presence of any hernias.

NONOPERATIVE MANAGEMENT