Ann Thorac Surg 2007;84:1053-1055
© 2007 The Society of Thoracic Surgeons
How To Do It
Partial Median "I" Sternotomy: Minimally Invasive Alternate Approach for Aortic Valve Replacement
Johannes Boehm, MDa,
Paul Libera, MDa,
Albrecht Will, MDb,
Stefan Martinoff, MDb,
Stephen M. Wildhirt, MD, PhDa,*
a Department of Cardiothoracic Surgery, German Heart Center Munich, Technical University of Munich, Munich, Germany
b Institute for Radiology, German Heart Center Munich, Technical University of Munich, Munich, Germany
Accepted for publication December 21, 2006.
* Address correspondence to Dr Wildhirt, Department of Cardiothoracic Surgery, German Heart Center Munich, Technical University of Munich, Lazarettstrasse 36, Munich, D-80636, Germany (Email: wildhirt{at}gmx.net).
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Abstract
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Minimally invasive aortic valve replacement using the inversed L-like partial upper sternotomy has evolved during the last 10 years. It is performed with excellent results with regard to sternal stability and cosmesis. However, the lateral incision may result in sternal overriding, instability, or fracture. We present an alternate minimally invasive approach to aortic valve replacement. We performed a partial median "I" sternotomy in 30 consecutive patients: After a 6- to 8-cm skin incision, the sternum was incised from the jugulum downward to the corpus, ending at the level of the fourth or fifth intercostal space. No lateral incision of the sternum was performed. The access to the heart and aorta was excellent. During the postoperative course and during follow-up, clinical examination revealed sternal stability and normal wound healing in all patients. These results show that the partial median I sternotomy can be performed safely and provides excellent clinical and cosmetic results.
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Introduction
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Minimally invasive aortic valve replacement using the inversed L-like partial upper sternotomy has evolved during the last 10 years. It is performed with excellent results with regard to sternal stability and cosmesis. However, the lateral incision may result in sternal overriding, instability, or fracture. As an alternate minimally invasive approach to aortic valve replacement, we performed a partial upper median "I" sternotomy, thereby avoiding the additional lateral incision of the sternum.
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Technique
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We enrolled 30 patients scheduled for elective valve replacement for isolated aortic valve disease at our institution between August 2004 and February 2006. Follow-up was 11.6 ± 4.9 months after surgery by physical examination and telephone interview. In addition, a computed tomography scan of the chest was performed in a 62-year-old patient 3 months after surgery.
During surgery, a 6- to 8-cm skin incision was made from about 3 cm below the jugulum downward (Fig 1). Using a conventional sternal saw, the midline incision was performed from the jugulum downward dividing the manubrium and partially the corpus of the sternum. The lower end of the sternal incision reached the level of the fourth or fifth intercostal space. No additional transverse incision to the right lateral aspect of the sternum was made (Fig 1A). Using a small retractor (Estech Europe, Lage Zwaluwe, the Netherlands), the sternum was carefully retracted until good access to the aorta and the heart was achieved. In all cases, the sternum was opened in a V-shaped manner without tearing the lower end of the sternal incision. It was helpful to position the retractor in the upper part of the sternum (Fig 1B). The width of the I incision is approximately 6 cm at the upper part of the sternum and about 4 cm at the level of the ascending aorta. Routine cannulation for extracorporeal circulation was performed with the arterial cannula in the ascending aorta and direct cannulation of the right atrial appendage for venous drainage. After aortic cross clamping, a vent was inserted into the left ventricle either through the right upper pulmonary vein or directly through the aortic root (Fig 1C). Myocardial protection was achieved by administration of cold crystalloid cardioplegia and mild systemic hypothermia (32°C). Resection of the valve, placement of the sutures, and anchoring of the prosthesis to the valve annulus were performed with conventional instruments without endoscopic instruments or knot-pusher. Transesophageal echocardiography was used in all patients to evaluate function of the implanted valve, to exclude paravalvular leak after termination of cardiopulmonary bypass, and to control for residual air during deairing.
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Fig 1. The skin incision is about 7 to 8 cm, beginning 3 cm below the jugulum. (A) The underlying sternotomy is approximately 10 cm. (B) Intraoperative view of the sternum after the retractor has been placed. (C) Excellent access of the heart and aorta enables canulation and aortic valve exposure similar to what is obtained during aortic valve surgery with conventional sternotomy.
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A mediastinal chest tube was inserted, either from anterolateral in the fifth intercostal space or through a tunnel from the xyphoid. The pleural spaces were not opened. After removal of the retractor, the sternal edges were in close proximity and the sternum was fairly stable. Four wires were used to close the chest, followed by closure of the fascia and soft tissues in layers. The mortality and stroke rates were 0% during follow-up. Patient demographics and postoperative outcome parameters are given in Table 1. During in-hospital stay and follow-up, no wound healing problems were observed, and the sternum was stable in all patients (Fig 2).
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Fig 2. Computed tomography scan of the chest was performed in a 63-year-old man 3 months after surgery. A reconstructive view showed the sternum from the (A) anterior, (B) lateral, and (C) posterior views. The sternal imaging was achieved by Siemens 64 multidetector row (Siemens Medical Solutions USA, Malvern, PA) computed tomography in a native scan. Axial slices with a thickness of 0.75 mm formed the raw data for three-dimensional reconstruction in a volume-rendering technique. Specially adapted window presets allow an anatomic view of the sternal region.
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Comment
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Minimally invasive aortic valve replacement has evolved during the last 10 years. It is routinely performed through an inversed L-shaped partial upper sternotomy, which requires an additional right lateral incision of the sternum [1, 2]. This method has been reported to provide good access to the heart and aorta and achieves excellent cosmetic results. The conversion rate to full sternotomy is reported to be less than 5%. However, the lateral incision may result in sternal dehiscence, overriding, or fracture, as reported previously [3].
The upper I sternotomy without a lateral incision of the sternum, as reported here, achieves excellent exposure of the heart, aorta, and aortic root. Once the retractor has been removed, the sternal plates are in close proximity, and the risk of overriding or sternal dehiscence is avoided. The skin incision of 6 to 8 cm is shorter than the underlying sternotomy and comparable to what has been reported for the upper inversed L-like sternotomy. By avoiding the lateral incision, the sternum remains very stable, and if required, conversion to a full sternotomy is easily achieved.
In the present study, patients were not specifically selected by body mass, sex, or absence of risk factors for mediastinitis. We did not include severely obese patients or those with orthopedic problems such as scoliosis. These are also exclusion criteria for other minimally invasive procedures performed at our institution. However, relatively slender patients have been operated on with this technique. In addition, the majority were male, and only 2 patients had diabetes mellitus. Moreover, for patients aged more than 70 years and for patients with fragile sternal plates, we avoided fracture of the sternum by opening the sternal retractor slowly, in a stepwise manner. Particularly in patients with severe osteoporosis, such as elderly women, retraction of a partially divided sternum should be performed with great care because their tissues are less tolerant of stress and may tear. This care resulted in excellent valve accessibility in every patient without tearing the sternal plates, and may account for the good results obtained with this technique.
When performing minimally invasive surgery, the benefit of a small incision should not compromise the surgical result, and poor exposure of the aortic valve or difficult anchoring of the valve to the annulus during surgery may lead to late paravalvular leak. That may particularly important for obese patients or for patients with chronic obstructive pulmonary disease, which may limit the exposure of the valve. We suggest that, whenever exposure is poor, to convert to full sternotomy, which is easily achieved by this technique because there is no lateral incision and the sternal plates remain intact. In our patients, early postoperative follow-up by echocardiogram demonstrated no signs of prosthesis malfunction and no paravalvular leak. In addition, the clinical results for the present study population did not show wound healing problems or instability of the sternum after an average follow-up of 11.6 ± 4.9 months.
Further studies are necessary to assess whether this technique may also be applied to more complex surgery on the aortic root and ascending aorta.
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Acknowledgments
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We gratefully thank Ute Lang for excellent technical assistance.
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References
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- Bakir I, Casselman FP, Wellens F, et al. Minimally invasive versus standard approach aortic valve replacement: a study in 506 patients Ann Thorac Surg 2006;81:1599-1604.[Abstract/Free Full Text]
- Walther T, Falk V, Mohr FW. Minimally invasive surgery for valve disease Curr Probl Cardiol 2006;31:399-437.[Medline]
- Tam RK, Almeida AA. Minimally invasive aortic valve replacement through partial sternotomy Ann Thorac Surg 1998;65:275-276.[Abstract/Free Full Text]
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Abstract
Introduction
