Manubrium–Sparing Median Sternotomy as a Uniform Approach for Cardiac Operations

Abstract

We used a manubrium-sparing sternotomy to perform intracardiac operations on 26 patients between November 1997 and April 1998. We developed this less-invasive surgical technique as a uniform approach in order to reduce skin and skeletal trauma, while maintaining the advantages of the full median sternotomy, such as standard aortic and venous cannulations and use of both antegrade and retrograde cardioplegia. During the same period, 26 other patients with intracardiac lesions underwent operation through a standard full sternotomy. In the manubrium-sparing sternotomy group, there was no intraoperative complication or conversion to full median sternotomy. The average postoperative chest drainage was less in the manubrium-sparing sternotomy group (242.7 ± 184.5 mL/24 hours, vs 499.2 ± 416.3 mL/24 hours; P <0.01). Two patients (7.7%) in the manubrium-sparing sternotomy group had superficial wound disruption, but 4 patients (15.4%) in the full sternotomy group had more severe wound infection, and 1 required myoplasty because of deep wound infection. During the mean follow-up period (12.4 ± 1.9 months), no patient in the manubrium-sparing sternotomy group reported significant discomfort or pain due to the sternotomy, but 6 patients (23.1%) in the full sternotomy group complained of significant sternal pain, while 4 (15.4%) experienced shoulder pain, and 1 (3.8%) experienced numbness of the 4th and 5th fingers of both hands. We conclude that the manubrium-sparing sternotomy is a safe and useful approach for most cardiac operations. It is effective in reducing surgical trauma and postoperative wound discomfort.

Smaller incisions accelerate physical recovery and produce cosmetic results that are more pleasing to patients. ^1–5 In recent years, cardiac operations have been performed through smaller incisions as alternatives to full median sternotomy, but no limited-access technique has been developed as a uniform approach for intracardiac surgery. Useful techniques have been developed primarily for specific procedures, such as aortic valve surgery, ^2,3 and some of the less-invasive methods require specialized instruments ^4,5 or modification of the incisions for application to other cardiac operations. ⁶ The ideal less-invasive incision will permit access to all areas of the heart, require minimal use of specialized equipment, and enable the patient to resume normal activities more quickly. While other surgeons were developing new incisions to access portions of the heart, we modified the traditional sternotomy and incorporated traditional cannulation techniques. In this report, we describe our technique of manubrium-sparing sternotomy, which has proved useful as a uniform less-invasive technique for most intracardiac operations.

Patients and Methods

From November 1997 to April 1998, 26 patients with congenital or acquired cardiac lesions underwent operations through manubrium-sparing median sternotomy (MSS). Ages ranged from 16 to 68 years (mean, 45.0 ± 17.7 years). Operations performed by this method included the following: replacement of the mitral valve and repair of the tricuspid valve (n = 8); repair of the mitral and tricuspid valves (n = 2); replacement of the aortic valve (n = 2); replacement of the aortic valve and coronary bypass grafting (n = 2); replacement or repair of the mitral valve and coronary bypass grafting (n = 2); repair of ventricular septal defect and ruptured sinus of Valsalva (n = 2); closure of atrial septal defect (n = 2); closure of ventricular septal defect and repair of the tricuspid valve (n = 2); replacement of the aortic and mitral valves and tricuspid valve repair (n = 1); en bloc resection of malignant mesenchymoma (coexisting malignant schwannoma and chondrosarcoma) in the left atrium (n = 1); closure of aorticopulmonary window (n = 1); double valve replacement, repair of the tricuspid valve, and modified maze procedure (n = 1).

To evaluate the effectiveness of the MSS, we compared outcomes of the MSS group with those of 26 other patients who underwent similar intracardiac procedures^* through full median sternotomy during the same 5 months. During the study period, the full sternotomy group first underwent operation consecutively, and then the MSS group underwent operation consecutively.

For this study, we excluded all patients who underwent redo valve operation, repair of aortic aneurysm or dissection, or only coronary bypass grafting during the study period.

Operative Procedure

We made a vertical skin incision that extended from the angle of Louis to the xiphoid. We started the midline sternotomy just to the side of the xiphoid and extended it to the level of the 1st intercostal space, where we extended it transversely to the left and right, taking care not to injure the intercostal pedicles (Fig. 1). We used a standard sternal saw (Stryker Instruments; Kalamazoo, Mich) to accomplish the vertical sternal division, and a sagittal saw with a deep-cutting blade (Stryker Instruments; Kalamazoo, Mich) to make the transverse osteotomy (Fig. 2). We left intact the upper 2/3rds of the manubrium and the xiphoid. After dividing the corpus sterni and the lower 1/3rd of the manubrium, we placed a standard sternal retractor and spread the sternal edges. We incised the pericardium vertically and suspended the edges from the skin, in order to further expose the cardiac structures, especially the ascending aorta and the right atrium. The ascending aorta and the bifurcation of the pulmonary artery were readily exposed, even without lifting the manubrium.

Fig 1. The manubrium-sparing median sternotomy follows the dotted line from either side of the xiphoid to the first intercostal spaces. The sternum is closed with peristernal and manubrium-to-sternum wires.

Fig 2. The manubrium-sparing sternotomy is easily performed with 2 types of oscillating saws: A) a standard sternal saw for the vertical sternotomy, and B) an osteotomy saw with a 1-inch blade for the transverse osteotomy.

We placed cannulation sutures in the standard location on the ascending aorta, and for most of the intracardiac lesions, we inserted 2 separate venous cannulae directly into the superior and inferior venae cavae. We also placed cannulae for antegrade and retrograde cardioplegia in the usual manner. We performed all cardiac procedures, including aortic and mitral valve work, using standard techniques.

Myocardial protection was accomplished primarily by intermittent antegrade and retrograde cold-blood cardioplegia and by continuous retrograde non-cardioplegic blood perfusion. On the rare occasions when defibrillation was required, a pair of adult's paddles fit easily within the incision. Pacing wires and a catheter for monitoring left atrial pressure were placed routinely.

To close the sternum, we used standard peristernal wires and an additional set of vertical wires from sternum to manubrium (Fig. 3).

Fig 3. Postoperative photograph of our 1st case. This patient underwent mitral valve replacement through manubrium-sparing sternotomy. The operative scar of about 12 cm is approximately half the length of the standard sternotomy incision.

Postoperatively, we used a verbal descriptor scale ⁷ to measure the intensity of pain in the sternum, shoulder, and upper extremities.

Continuous data were analyzed by unpaired Student's t test, and discontinuous variables were analyzed by 2 or Fisher's exact test. Continuous data are presented as the mean value ± the standard deviation. A probability value of less than 0.05 was considered statistically significant.

Results

There was no hospital death during the 6-month study period, and no patient who underwent MSS required conversion to full sternotomy. Left atrial procedures, including en bloc resection of malignant mesenchymoma in the left atrium, internal closure of left atrial appendage, and the maze procedure, could be performed without difficulty.

As shown in Table I, there were no significant differences between the 2 groups in age, cardiopulmonary bypass time, aortic cross-clamp time, postoperative transfusion amount, postoperative wound problems, injury of mediastinal pleura, ventilator support time, or length of stay. The average postoperative chest drainage was less in the MSS group (242.7 ± 184.5 mL/24 hours vs 499.2 ± 416.3 mL/24 hours; P <0.01). Two patients (7.7%) in the MSS group had skin wound disruption that healed before discharge when treated with drainage and skin suture. However, 3 patients (11.5%) in the full sternotomy group had soft-tissue wound infection, and 1 patient (3.9%) required myoplasty because of deep sternal wound infection.

Table I. Clinical Characteristics of the Manubrium-Sparing Sternotomy and Full Sternotomy Groups

In the MSS group, 18 patients (69.2 %) complained of temporary wound pain at the transverse osteotomy site in the 1st intercostal space. This pain occurred only during the hospital stay and disappeared shortly after discharge. During the follow-up period (12.4 ± 1.9 months), no patient in the MSS group complained of sternal pain, shoulder pain, or any neurologic symptom. In the full sternotomy group, however, 6 patients (23.1 %) reported significant delayed sternotomy pain, while 4 patients (15.4 %) complained of shoulder pain, and 1 patient (3.8 %) experienced numbness of the 4th and 5th fingers of both hands (Table II).

Table II. Late Postoperative Symptoms Reported by Manubrium-Sparing Sternotomy Patients and by Standard Full Sternotomy Patients during the Follow-up Period

Discussion

New techniques for cardiac operations are being evaluated for their potential to reduce perioperative morbidity and accelerate postoperative recovery. Careful evaluation of the MSS technique is required to determine its usefulness as a uniform approach for most cardiac operations, as compared with the standard procedure.

We were encouraged by Moreno-Cabral's letter, ⁴ published in April 1997, which described a mini-T sternotomy. This technique divides the sternum transversely in the 2nd intercostal space and vertically through the lower 2/3 of the sternum. We were particularly interested in the small incision and simple midline approach. However, this procedure requires retractor elevation of the intact upper sternum in order to obtain good exposure, which makes the work troublesome and uncomfortable for the surgeon. To adjust for this, some surgeons have separated the manubrium from the corpus sterni in an inverted V-shaped line. ⁸

We achieved the same effect by making the T-sternotomy 1-interspace higher than in Moreno-Cabral's technique, without upward extension of the skin incision. Our modified technique enabled aortic cannulation near the pericardial fold and eliminated the need for a special retractor for the manubrium. In patients who underwent coronary bypass grafting, we had enough space for proximal dissection of a skeletonized internal thoracic artery. Although the MSS is 1-interspace higher than in Moreno-Cabral's mini-T sternotomy, the skin incision is not as long, and it involves less upward dissection of the skin and less separation of subcutaneous tissue from muscle. Because the distance between the internal thoracic arteries and the sternal margin is nearly constant from the 1st to the 3rd intercostal space, ⁹ there is no difference between the mini-T sternotomy and the MSS in protecting both internal thoracic arteries. To avoid injury to the internal thoracic arteries, however, the sternal edges that are divided vertically should not be spread wide initially, especially not before an internal thoracic artery is harvested for coronary bypass grafting.

The narrow and deep operative field through a partial sternotomy may make intracardiac procedures more difficult. In addition to using the MSS for coronary bypass grafting, therefore, we also tried it for operations that require a deep operating field, such as multiple valve replacement and en bloc resection of malignant mesenchymoma in the left atrium. We found that the MSS provided an adequate operating field in these cases.

Our initial experience with the MSS approach suggests several definite advantages. First, the incision is cosmetically acceptable to patients. At about 12 cm, the MSS incision is a little longer than the incisions made for other minimally invasive sternotomy techniques, but it is still much smaller than the incision for conventional median sternotomy. This is especially important to younger patients because they are often reluctant to have a scar near the neck.

Second, the patients in the MSS group experienced less pain than those who underwent full sternotomy. Some of the MSS patients reported pain at the transverse sternotomy site in the 1st intercostal space. However, this occurred only during the hospital stay, and in every case it had abated by the time of the outpatient visit, about 2 weeks after discharge. Furthermore, some of the patients in the full sternotomy group experienced shoulder pain or numbness of the 4th and 5th fingers, but none of the MSS patients experienced these symptoms. We believe that the MSS patients experienced less pain because when the upper 2/3rds of the manubrium is left intact, the clavicle and the 1st rib remain undisturbed, and the brachial plexus is not stretched or injured. The patients who underwent MSS could move their upper extremities soon after discharge, and they experienced no persistent sternotomy pain later on. These were the most striking advantages of the MSS approach.

The MSS technique did not reduce the mean cardiopulmonary bypass time when compared with full sternotomy. However, the amount of postoperative drainage in the MSS group was significantly smaller. This may be the result of leaving the upper manubrium and the xiphoid intact and of limiting dissection of their adjacent tissues.

Another advantage of the MSS resulted from leaving the skin intact on the xiphoid. The sternotomy was started from either side of the xiphoid, and the xiphoid was not divided. Under full median sternotomy incision, the skin incision in the area of the xiphoid is vulnerable to delayed healing and wound disruption, especially in aged, diabetic, or obese patients. Our study suggests that this can be readily prevented by avoiding skin incision on the xiphoid.

Despite their increasing use, many minimally invasive cardiac operations have definite disadvantages. Many techniques require incisions that are unfamiliar to most practicing surgeons. Furthermore, these procedures often require less-suitable cannulation of vessels, such as the femoral artery or vein. ^10,11 The 2 structures necessary to institute bypass, the ascending aorta and the right atrial appendage, are essentially upper midline structures that should be within easy reach if the upper sternum is divided adequately. ⁶ The MSS provides a sufficient upper retrosternal space and allows the use of standard cannulae, standard myocardial protection techniques, and standard surgical techniques.

Doty and colleagues described a less-invasive technique that may be used to perform most cardiac operations, ⁵ but it requires more skill, more caution, and a separate surgical aperture in order to use standard instruments and surgical techniques. The MSS technique does not require more skill, more caution, or even a learning period.

We conclude that manubrium-sparing median sternotomy can be used as a uniform approach for most intracardiac procedures. It enables facile less-invasive cardiac surgery and uses standard instruments and surgical techniques. It does not require lifting the intact upper sternum in order to achieve good operative exposure. In our study, sternal discomfort was limited to the transverse osteotomy site, and this occurred only during the hospital stay. After discharge, no patient had sternal pain, shoulder pain, or any neurologic deficit.