What is the surgical procedure for minimally invasive repair of pectus excavatum (MIRPE)?

Updated: Oct 30, 2018
  • Author: Andre Hebra, MD; Chief Editor: Girish D Sharma, MD, FCCP, FAAP  more...
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Answer

The patient is placed in the supine position with both arms abducted at the shoulders to allow access to the lateral chest walls.

The patient is prepared for surgery and draped such that the entire anterior chest is exposed, including the lateral chest wall (broad exposure).

The chest is marked with a sterile marking pen in the deepest portion of the pectus (making sure that it is not inferior to the sternum), on the corresponding intercostal spaces on the right and left sides where the bar is to be inserted, and on the points on the pectus ridge that correspond to the horizontal plane from the deepest point of the pectus to the lateral chest wall incisions.

At this time, the measurement of the Lorenz pectus bar is reconfirmed using the marks made on the chest. The length of the Lorenz bar should be measured from the mid-axillary line in one side to the opposite mid-axillary line. The length of the bar is measured in inches. A typical measurement for a teenage patient may range from 13-inches.

The bar is bent from the center out to either end, making small gradual bends with a Zimmer bar bender. The curvature (convexity) of the bar is shaped to fit each individual patient's chest. Occasionally, slightly exaggerating the curvature to allow for the anterior chest wall pressure that may alter the original configuration of the bar may be necessary. The bar must fit snugly over the chest.

A transverse 2-cm skin incision is made on the midaxillary line at the level of the skin marks in line with the deepest point of the depression on the right and left sides.

A skin tunnel is raised anteriorly from both incisions to the top of the pectus ridge at the previously selected intercostal space; the skin pocket is extended posteriorly to allow for the distal end of the pectus bar to hug the chest wall posterior to the midaxillary line.

A thoracoscope is inserted at this point. The authors recommend placement of a 5-mm trocar 1-2 intercostal spaces below the space that has been chosen for the pectus bar on the patient's right side. The image below illustrates the placement of the thoracoscope. A 30° thoracoscope provides excellent visualization of the pleural cavity, lung, and mediastinal structures.

Illustration showing the minimally invasive techni Illustration showing the minimally invasive technique for correction of pectus excavatum (3) with thoracoscopy (1). Note the long clamp passed from one side to the other (2) grabbing the umbilical tape (4), which serves as a guide for passage of the pectus bar behind the sternum.

If necessary, the scope can be used bilaterally. Insufflating the pleural cavity with carbon dioxide is rarely necessary; in most cases, controlled ventilation by the anesthesiologist with small tidal volumes results in limited lung expansion and good thoracoscopic visualization of vital structures.

Using a thin but deep retractor, the skin incisions are elevated and the intercostal space previously marked is identified. A long instrument, such as a 15-in Crawford vascular clamp or a Lorenz pectus introducer (S-shaped device), is inserted through the appropriate right intercostal space at the top of the pectus ridge, in line with the point that corresponds to the deepest depression of the sternum (previously marked). The image below illustrates the steps described here.

Illustration showing the minimally invasive techni Illustration showing the minimally invasive technique for correction of pectus excavatum (3) with thoracoscopy (1). Note the long clamp passed from one side to the other (2) grabbing the umbilical tape (4), which serves as a guide for passage of the pectus bar behind the sternum.

The clamp or introducer is slowly advanced across the anterior mediastinal space immediately under the sternum with careful videoscopic guidance. Always face the point of the instrument anteriorly (away from the heart) and maintain contact with the sternum to avoid injury to mediastinal structures.

The sternum is forcefully lifted as the instrument is passed to the contralateral side. Monitoring for cardiac ectopy is important to ensure that the instrument is not near the heart or pericardial sac.

Once the instrument is passed behind the sternum, the tip is pushed through the intercostal space at the top of the pectus ridge on the left side (also previously marked) and brought out through the left skin incision. Thoracoscopy on the left side is not usually necessary unless the position of the instrument in the left chest is uncertain.

The Crawford clamp, if used, is advanced such that the tunnel space created is enlarged; if the Lorenz pectus introducer is used, further dilating the space is not necessary. Note that the Lorenz pectus introducer comes in 2 sizes: short, for younger patients aged 4-12 years who have a small chest, and long, for older and larger patients aged 13-20 years.

Using the clamp or the introducer, 2 strands of umbilical tape are pulled through the tunnel; one tape is used as a spare. See the image below.

Illustration showing the minimally invasive techni Illustration showing the minimally invasive technique for correction of pectus excavatum (3) with thoracoscopy (1). Note the long clamp passed from one side to the other (2) grabbing the umbilical tape (4), which serves as a guide for passage of the pectus bar behind the sternum.

One of the tapes is used to guide the previously prepared pectus bar through the tunnel and anterior mediastinal space using traction on the tape and concomitant thoracoscopic visualization. The bar is inserted with the convexity facing posteriorly. The image below is an illustration of the bar in place before it is turned over.

Operative diagram illustrating the pectus bar afte Operative diagram illustrating the pectus bar after it has been passed behind the sternum (5), under thoracoscopic visualization (1), before turning it over. Note that the concavity of the bar is facing up.

Using a Lorenz pectus bar rotational instrument (also known as a "bar flipper"), the bar is turned over so that the concave part now faces posteriorly (to the mediastinum) and the convex part faces anteriorly. The ends of the bars are placed in the subcutaneous tissue, anterior to the muscle fascia (not under it and not within the muscle tissue). Again, the bar must hug the chest so that the ends do not protrude under the skin pocket. The "flipping maneuver" is also performed under careful thoracoscopic visualization.

If, after the bar is flipped, the correction of the pectus excavatum is not ideal (either undercorrected or overcorrected), the bar is flipped back, pulled back out, and bent again to fit the patient's chest in order to achieve the best possible correction of the deformity. If pressure has caused the bar to straighten, it is turned over and, using small hand held benders, the curvature is increased as appropriate. This can be repeated as many times as necessary. Typically, only one bar is necessary to correct the deformity, but, occasionally, a second bar may be necessary. The second bar can be placed above or below the first one. The thoracoscope and trocar are removed at this point.

Once the bar is in place, determining its stability is imperative. Such assessment dictates the need for placement of a stabilizing bar. The stabilizer serves to limit rotation of the pectus bar, and it is sutured around the bar and to the muscle only after being properly fitted. Teenagers usually require one stabilizer bar that can be placed on either side of the pectus bar.

With the bar properly placed and stabilized, figure-of-eight sutures are placed to the lateral chest wall musculature. Number 0 nonabsorbable sutures (Prolene) are placed on one side, and absorbable (Vicryl or PDS) sutures are placed on the opposite side. The image below illustrates the positioning of the bar in relationship to the chest wall and muscles.

Illustration of the pectus bar passed behind the s Illustration of the pectus bar passed behind the sternum before and after it is turned over. The insert shows the proper technique for fixation of the pectus bar against the lateral chest wall musculature.

Additionally, a third point-of-fixation suture can be placed on the anterior chest to the side of the sternum, around one rib and around the pectus bar, in order to provide another point of fixation for the bar, minimizing the chance of bar displacement. The image below illustrates the technique for placement of the third point of fixation.

Illustration of the placement of the third point o Illustration of the placement of the third point of fixation for stabilization of the pectus bar. Note that the nonabsorbable suture is placed around the bar and around a rib, lateral to the sternum on the anterior chest wall.

At this point, the anesthesiologist places the patient in the Trendelenburg position, and large tidal volumes are used in combination with positive-end expiratory pressure (PEEP) so that any residual pneumothorax is eliminated. A chest tube is rarely needed. The subcutaneous tissue and skin are reapproximated with absorbable sutures. Chest radiography is performed as soon as possible to confirm good lung expansion and to reveal the final positioning of the bar.

The patient is extubated deeply to minimize any movement and/or agitation because this may result in bar displacement as the patient thrashes about.


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