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Ann Thorac Surg 2001;72:S1041-S1045
© 2001 The Society of Thoracic Surgeons

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Supplement: Cardiothoracic techniques and technologies

Partial median sternotomy as a minimal access for off-pump coronary artery bypass grafting: feasibility of the lower-end sternal splitting approach

^a Department of Cardiovascular Surgery, Daini Hospital, Tokyo Women’s Medical University, Tokyo, Japan

Address reprint requests to Dr Niinami, Department of Cardiovascular Surgery, Daini Hospital, Tokyo Women’s Medical University, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567, Japan
e-mail: niinamca{at}dnh.twmu.ac.jp

Presented at the Seventh Annual Cardiothoracic Techniques and Technologies Meeting 2001, New Orleans, LA, Jan 24–27, 2001.

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Off-pump coronary artery bypass grafting (OPCAB) can be performed in several ways using a minimally invasive approach (MIDCAB). Using the left anterior small thoracotomy (LAST) approach, only the LAD can be grafted. To expand the indications for MIDCAB from single-vessel disease to double-vessel disease, we have used a partial sternotomy without a transverse cut, namely, the lower-end sternal splitting (LESS) approach. Through this approach, the LAD and RCA can be revascularized by means of a single small incision without the risk of damaging the tissue around the intercostal space during harvesting of ITA when the sternum is transversely divided. The purpose of this study was to demonstrate the feasibility and safety of this technique.

Methods. Between November 1999 and November 2000, a total of 22 patients underwent MIDCAB through a lower midline skin incision from the fourth intercostal space to the xiphoid process with longitudinal division of the lower half sternum up to the 3rd rib, without either a T- or reversed L-shaped division of the sternum. Of the patients, 14 had LAD disease only, 5 had both LAD and RCA disease, 2 had RCA disease only, and 1 had left main trunk disease. Two of the operations were of redo coronary artery bypass grafting. The mean age was 69.5 ± 6.1 years (range 58 to 77 years).

Results. The mean length of the skin incision was 8.5 ± 1.4 cm (range 7 to 12 cm). No hospital death or morbidity was observed. All patients had arterial conduits: LIMA in 20 patients, RIMA in 3, RGEA in 4, and RA in 1. The mean number of grafts per patient was 1.3 ± 0.6 (range 1 to 3). No blood transfusion was required perioperatively. The patency rate was 96%. All patients were in New York Heart Association class I and no wound complications or postoperative pain occurred during follow-up.

Conclusions. Our experience demonstrates that the LESS approach for MIDCAB is technically feasible for revascularizing not only the LAD but also the RCA system, with the same small incision using IMA and GEA. It can be used with excellent cosmetic results and safety. Although our experience is limited, we conclude that this less invasive surgical technique can be used as an alternative approach for MIDCAB in patients with LAD or RCA disease.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Recent enthusiasm for off-pump coronary bypass grafting (OPCAB) has been generated by the minimally invasive direct coronary artery bypass (MIDCAB) procedure, as described by Benetti [1], and as expanded and validated by Calafiore and colleagues [2] as the left anterior small thoracotomy (LAST) approach. However, minimally invasive approaches with a single incision generally permit the exposure of a single coronary artery. When multiple vessel revascularization is required, although combined minimally invasive approaches have been described [3], full sternotomy is generally preferred [4]. To expand the indications for MIDCAB from single-vessel to double-vessel disease, other approaches are currently used that allow grafting of the left anterior descending artery (LAD) and right coronary artery (RCA) systems simultaneously with one small incision, using the lower half ministernotomy technique [5, 6]. These techniques usually require transverse division of the sternum, which can cause trauma to the thoracic wall, especially damage to the internal thoracic arteries (ITA), when the ITA retractor is applied to the sternum. Furthermore, there is a potential risk for pseudojoint of the sternum. We began to use the lower half ministernotomy technique without transverse division of the sternum, namely, the lower-end sternal splitting (LESS) approach [7]. This approach provides the least trauma to the chest wall without compromising optimal exposure of both the anastomotic field and the ITA. The aim of this study was to demonstrate the feasibility and safety of this technique.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Patients who had major coronary artery stenosis (> 75% angiographic diameter stenosis) limited to a single or double coronary distribution on the anterior and inferior surface of the heart were selected for revascularization using MIDCAB through the LESS approach. All patients had symptoms refractory to medical treatment and were not candidates for further catheter-based interventions. Exclusion criteria for the LESS approach included the presence of major coronary artery disease on the lateral or posterior surface of the heart and acute myocardial infarction requiring intravenous administration of nitrates or an intraaortic balloon pump. Patients were not excluded on the basis of the age, functional status, reoperation, or other preoperative risk factors, such as previous stroke or myocardial infarction.

Between November 1999 and November 2000, a total of 22 patients underwent MIDCAB using the LESS approach. There were 16 men and 6 women, with a mean age of 69.5 ± 6.1 years (range 58 to 77 years). Functionally, 3 patients were in New York Heart Association (NYHA) functional class III before operation, 11 were in class II, and 8 were in class I. A previous PTCA had been performed in 2 patients. Of the patients, 14 had LAD disease only, 5 had both LAD and RCA disease, 2 had RCA disease only, and 1 had left main trunk disease. Two of the operations were redo CABG. Before operation, the mean left ventricular ejection fraction was 62.1% ± 13.4% (range 38% to 77%). Six patients had a history of one or two acute myocardial infarctions. Seven patients were diabetic and 1 had a history of stroke. Two patients had renal insufficiency and 1 was on hemodialysis. Preoperatively, in all patients, the size of the LITA or GEA was evaluated by angiography during cardiac catheterization.

All patients received arterial grafts. The mean number of grafts per patient was 1.3 ± 0.6 (range 1 to 3 grafts). The surgical access routes and type of grafts used are listed in Table 1.

The patient was placed in a supine position and prepared as for conventional cardiac surgical procedures. A vertical skin incision was made from the fourth intercostal space to the xiphoid process (7 to 8 cm). The lower half of the sternum was then divided up to the third rib starting from the bottom, using an oscillating saw, without making either a T- or reversed L-shaped division of the sternum. A traditional ITA retractor (Rultract, Inc. Cleveland, OH) was used to procure ITA using a Harmonic Scalpel (Ethicon Endo-Surgery, Inc, Somerville, NJ) with a skeletonized technique. The ITAs were exposed and harvested to the usual extent obtained with full sternotomy. When using the right gastroepiploic artery (GEA), a skin incision needed to be extended caudally about 2 to 3 cm. The GEA was exposed through a small laparotomy and harvested by dividing the branches with the Harmonic Scalpel. When the radial artery (RA) was used, it was harvested from the left forearm simultaneously with the left ITA (LITA), using the Harmonic Scalpel. After all conduits were harvested, the sternum was gently spread just enough to allow for adequate visualization and great care was taken to avoid fractures around the third intercostal space. The pericardium was opened up to the aortic root. Heparin was given (1 to 1.5 mg/kg) to keep the activated clotting time around 300 seconds. The distal part of all conduits were then ligated and divided. Then, the GEA pedicle graft was routed anteriorly to the pylorus and the left liver lobe and positioned in the pericardial sac through a hole in the diaphragm anterior to the inferior vena cava (IVC). A coronary artery stabilizer (CAB Super-Slide Retractor, T, Koros Surgical Instruments Corporation, Moorpark, CA, or Octopus, Medtronic, Inc, Minneapolis, MN) was set on the spreader. A 1 Vicryl suture with a big tapered needle (J359H Ethicon, Inc, Cincinnati, OH) was placed into the pericardium near the left lower pulmonary vein. This suture was gently pulled upward and secured to the surgical drape with the hemostat on the left side, bringing up the LAD to the field [8]. For the LAD anastomosis, a pressure-type stabilizer (T, Koros Surgical Instruments) was used. The anastomotic site of the LAD was chosen, and a 4-0 Prolene suture (Ethicon, Inc, Cincinnati, OH) was passed around proximally to the anastomotic site of the coronary artery using a snare with a Teflon felt pledget. A 5-minute test occlusion was undertaken routinely to confirm hemodynamic stability before proceeding with the arteriotomy and grafting, excluding cases of total occlusion of the coronary artery. When hemodynamic instability occurred, an internal shunt (AnastaFlo, Baxter Research Medical, Inc, Midvale, UT) was inserted. The LAD was opened longitudinally and the proximal suture was snared gently to obtain hemostasis. The LITA–LAD anastomosis was carried out using the 8-0 Prolene single parachute technique. For the anastomosis on the main RCA, a suction-type stabilizer (Medtronic, Inc) was used. The main RCA was opened longitudinally and the right ITA (RITA)–RCA or GEA–RCA anastomosis was then carried out using the 8-0 Prolene single running suture. For the anastomosis on the right posterior descending artery (PDA), another Vicryl suture with a big tapered needle was placed on the diaphragmatic surface of the pericardium and slightly deeper from the IVC [8]. This suture was pulled caudally to bring up the PDA to the field. Then, the acute margin of the heart was displaced cranially by the Octopus stabilizer to provide a good exposure of the inferior wall. The anastomotic site of the PDA was chosen and the GEA-PDA or RA-PDA anastomosis was performed with a running 8-0 Prolene suture. When the RA graft was used, a Y graft was constructed with the RITA after the distal anastomosis with a running 8-0 Prolene suture. Once the anastomosis was complete, the graft flow was tested using a hand-held transit-time ultrasonic flow probe (Transonic Systems, Inc, Ithaca, NY) to assist in the detection of technical problems with the anastomosis. Heparin was not reversed, or a half dose of Protamine was given at the end of the procedure. After insertion of two 8-mm drains into the pericardial cavity and the substernal space, the lower sternotomy was closed with sternal wires or Mersilene tapes and PDS codes (Ethicon, Inc, Cincinnati, OH) and soft tissue was closed in layers.

Patient follow-up
Electrocardiograms were recorded at least three times during admission, and serial myocardial fractions of creatine kinase (CK-MB) were determined at 1 hour and 16 hours postoperatively in all patients. Perioperative myocardial infarction was diagnosed in the presence of one or both of the following criteria: (1) CK-MB levels greater than 50 IU/L, and (2) the development of new Q-waves. After extubation, all patients were given oral analgesic tablets (loxoprofen sodium 180 mg/d) three times daily. Coronary angiography was performed in all patients within 1 month after surgery. Pain intensity was analyzed using the verbal rating scale [9]. This scale has a five-step approach and allows differentiation between no pain, and mild, moderate, severe, and unbearable pain. Postoperative pain assessment was performed on a daily basis for 7 days by direct interview. The patients were followed prospectively after operation at our outpatient clinic on a monthly basis.

Statistical analysis
All data are presented as mean ± standard deviation. The 95% confidence intervals (CI) for mortality, morbidity, and graft patency were calculated using the exact binomial distribution. Postoperative NYHA functional class was compared with preoperative status using a paired t test. A value of p less than 0.05 was considered significant.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
A total of 22 patients underwent MIDCAB using the LESS approach over a 12-month period from November 1999 to November 2000. Of these, 20 patients underwent a primary operation and 2 patients a reoperation. Neither hemodynamic changes nor transient S-T segment changes on the ECG occurred during the operation. The mean operative time was 189 ± 67 minutes (range 124 to 405 minutes) in all patients and was 159 ± 22 minutes (range 124 to 201 minutes) for single graft operations. The mean length of the skin incision was 8.5 ± 1.4 cm (range 7 to 12 cm).

There was no operative or follow-up mortality (CI 0% to 15.4%). In 1 patient (4.5%), transient atrial fibrillation was observed (CI 0.1% to 22.8%). In most patients, recovery was rapid and uneventful. All patients were extubated on the same day of the surgery and their intensive care unit stay was 1 day. On postoperative day 1 both drains were removed in all patients. No blood transfusion was required perioperatively in any patient. No patient had perioperative myocardial infarction (CI 0% to 15.4%). The median peak of the CK-MB was 7.2 IU/L (range 2 to 17 IU/L).

Patients experienced the most pain when coughing and during in-bed mobilization. Maximal pain levels were observed on postoperative day 2. Pain intensity according to the verbal rating scale at postoperative day 2 was no pain in 7 cases, mild in 10, moderate in 2 and severe in 1, which was reduced at postoperative day 6 to almost no pain (no pain in 19 cases and mild in 3). Early postoperative pain levels were relatively low as reflected by more patients expressing mild, or even no pain. The character of the pain was dull in most cases and aching was rare. After 1 week, almost all patients had no pain.

Postoperative angiography was performed in all patients. One patient had occlusion of the LITA graft. This patient was an elderly man who was judged to be beyond further attempts for surgery. The overall patency rate was 96% (CI 51.4% to 99.9%). At follow-up examination, NYHA functional class was significantly improved from 1.7 to 1 (p < 0.0001), and no wound complications or postoperative pain occurred.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Recent efforts in all areas of surgery have focused on minimally invasive surgical techniques. In cardiac surgery, there are two important aspects of this concept: (1) minimal access to limit surgical trauma, and (2) avoidance of cardiopulmonary bypass. Myocardial revascularization without cardiopulmonary bypass was originally discussed by Kolessov in 1967 [10]. Subsequently it was described by Benetti [1] and by Calafiore and colleagues [2], whose success led to enthusiasm about eliminating extracorporeal support for CABG. Early attempts were limited to the left anterior thoracotomy approach through which only the LAD can be grafted. In patients who require multiple vessel revascularization, conventional full sternotomy is preferred [4]. Several satisfactory approaches have been proposed to expand the indications of beating heart surgery for multiple vessel disease patients without full sternotomy [3, 6]. However, access to both RCA and LAD requires two incisions if the anterior small thoracotomy approach is used, frequently resulting in incisions with total lengths that are almost the same or greater than those of a full sternotomy. In contrast, the lower ministernotomy approach provides ease of access to both vessels by means of a limited incision and allows ITA harvest under direct vision.

Lower ministernotomy generally requires partial or total transverse division of the sternum at the level of the third intercostal space, which involves some potential risks; injury to the ITA around the third intercostal space when the lower hemisternum is elevated by the ITA retractor, sternal nonunion, and subsequent pseudojoint formation. With the use of the LESS approach, these complications can be eliminated.

The results obtained from this study are compatible with the reported series using the LAST approach, in terms of mortality, major morbidity, ICU stay, and graft patency [2]. However, the LESS approach shows some advantage over the LAST approach for MIDCAB. First, three arterial conduits can be harvested through a single incision: LITA, RITA, and GEA. These three conduits are available as in situ grafts, so that the "aortic no-touch" technique can be performed. It is advantageous to avoid touching the ascending aorta, especially in patients with a poor aorta, to minimize perioperative stroke. With respect to the harvesting of the ITAs through the LESS approach, this method provides traditional exposure with which the cardiac surgeon is familiar and allows direct visualization of the field of operation using traditional instruments. In contrast, with the LAST approach there is a risk of damaging the LITA during harvesting, since this is a technically demanding procedure for harvesting the LITA, and a learning curve exists [11].

Second, with the LESS approach, postoperative wound pain is slight. This is not a comparative study, but some studies have demonstrated that the LAST approach causes significantly more pain in the early postoperative period than with conventional full sternotomy [9, 12]. Strain caused by mobilization causes bony friction of the sternum in patients with full sternotomy. In particular, when patients moved their arms, they experienced intense pain due to friction of the split manubrium sterni because of the sternoclavicular joints. We believe that with our approach, patients should experience less pain than with full sternotomy, as the manubrium sterni is intact. In fact, in our study, most patients including elderly ones could walk around the ward soon after removal of chest tubes without any assistance. Furthermore, Ng and associates [13] demonstrated that wound complications after MIDCAB with the LAST approach were not insignificant. In their study, the wound complication rate for LAST approach was 9.1%, and this was significantly higher than the rate for median sternotomy. They suspected that the difference in morbidity between LAST and median sternotomy could be due to the lack of collateral blood supply to the intercostal muscle. Usage of bilateral ITA in patients with diabetes can involve a higher risk of mediastinitis after median sternotomy; however, using the LESS approach and skeletonized technique for harvesting ITA could reduce the incidence of this risk.

Third, the incision can be easily and rapidly extended to a full sternotomy when technical problems are encountered or the exposure is not adequate, in contrast to the LAST approach, which requires an additional incision. Compared to the ministernotomy approach with transverse division of the sternum, with the LESS approach the sternal retractor can be applied without sternal instability after conversion.

The major advantage of the LAST approach for MIDCAB compared with the LESS approach might be avoidance of a median sternotomy. This would eliminate postoperative mediastinitis, and is beneficial in patients who have undergone a previous median sternotomy. We did not encounter any cases of redo CABG after our procedure. However, the pericardium is completely closed in all patients, so median resternotomy should not be a problem.

Our experience demonstrates that the LESS approach for MIDCAB is technically feasible for revascularization not only of the LAD but also the RCA system with the same small incision using IMA and GEA, which can be advantageous over the LAST approach. This study also shows that our approach can be used with excellent cosmetic results and safety. Although our experience is limited, we conclude that this less invasive surgical technique can be used as an alternative approach for MIDCAB in patients with LAD or RCA disease.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Benetti F.J. Direct coronary surgery with saphenous vein bypass without either cardiopulmonary bypass or cardiac arrest. J Cardiovasc Surg 1985;26:217-222.[Medline]
2. Calafiore A.M., Di Giammarco G., Teodori G., et al. Midterm results after minimally invasive coronary surgery (LAST operation). J Thorac Cardiovasc Surg 1998;115:763-771.[Abstract/Free Full Text]
3. Voutilainen S., Verkkala K., Jarvinen A., et al. Minimally invasive coronary artery bypass grafting using the right gastroepiploic artery. Ann Thorac Surg 1998;65:444-448.[Abstract/Free Full Text]
4. Buffolo E., Andrade J.C.S., Branco J.N.R., et al. Coronary artery bypass grafting without cardiopulmonary bypass. Ann Thorac Surg 1996;61:63-66.[Abstract/Free Full Text]
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6. Grandjean J.G., Canosa C., Mariani M.A., Boonstra P.W. Reversed-J inferior sternotomy for beating heart coronary surgery. Ann Thorac Surg 1999;67:1505-1506.[Abstract/Free Full Text]
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9. Walther T., Falk V., Metz S., et al. Pain and quality of life after minimally invasive versus conventional cardiac surgery. Ann Thorac Surg 1999;67:1643-1647.[Abstract/Free Full Text]
10. Kolessov V.L. Mammary artery-coronary artery anastomosis as a method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967;54:535-544.[Medline]
11. Wiklund L., Johanson M., Bugge M., et al. Early outcome and graft patency in mammary artery grafting of left anterior descending artery with sternotomy or anterior minithoracotomy. Ann Thorac Surg 2000;70:79-83.[Abstract/Free Full Text]
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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Yasuo Takeuchi Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Niinami, H. Articles by Suda, Y. Search for Related Content PubMed PubMed Citation Articles by Niinami, H. Articles by Suda, Y. Related Collections Minimally invasive surgery