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Ann Thorac Surg 1999;67:567-568
© 1999 The Society of Thoracic Surgeons

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How To Do It

Protective wrapping of the internal thoracic artery

^a Division of Cardiothoracic Surgery, Phoenix Baptist Medical Center, Phoenix, Arizona, USA

Accepted for publication July 16, 1998.

Address reprint requests to Dr Vaughn, Cardiothoracic & Vascular Surgeons Ltd., 6036 North 19th Ave, Suite 405, Phoenix, AZ 85015

	Abstract

Top Footnotes Abstract Introduction Technique Comment References

 
Injury of a patent internal thoracic artery bypass graft in a patient during cardiac reoperation could have catastrophic results. In selected patients who have primary coronary artery bypass grafting using the internal thoracic artery, we wrap the artery pedicle with an expanded polytetrafluoroethylene membrane to facilitate identification and to protect it during reoperation. No occlusions or other complications related to use of the membrane have occurred.

	Introduction

Top Footnotes Abstract Introduction Technique Comment References

 
Injury of a patent internal thoracic artery (ITA) bypass graft during resternotomy for cardiac operations could result in myocardial infarction or death. The incidence of this problem is unknown; however, in a series of 410 patients who had repeat coronary artery bypass grafting, injury to the ITA graft occurred in five of 97 patients with such a graft. One of the five patients had severe bleeding and died [1]. Injury of an ITA graft at reoperation is generally caused by adhesions that make it difficult to identify the ITA pedicle. An absence of adhesions would reduce the risk of ITA injury [2] during dissection with scissors. Expanded polytetrafluoroethylene (ePTFE) does not conduct heat and prevents reoperative injury of the ITA with electrocautery. Wrapping of the ITA with autologous pericardium would not offer that protection.

Various surgical techniques and materials have been used experimentally and clinically to protect the ITA bypass graft during reoperation [2–6]. We describe a method that involves wrapping the ITA pedicle in a thin membrane of ePTFE material.

	Technique

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Two configurations of ePTFE membrane can be used to wrap the ITA; one is a sleeve (PRECLUDE IMA Sleeve, W.L. Gore & Associates, Inc, Flagstaff, AZ) and the other is a sheet (PRECLUDE Pericardial Membrane, W.L. Gore & Associates, Inc). Both products are made of a low-porosity form of ePTFE.

The ePTFE sleeve or sheet can be soaked in warm saline solution before use to increase its flexibility and ease of handling. The ITA is harvested from the chest wall in standard fashion before cardiopulmonary bypass is initiated. When the sleeve is used, the ITA is pulled through it and an accordion pleat is made in the sleeve to keep it out of the way during anastomosis. After the anastomosis has been completed, the sleeve is straightened and its proximal and distal ends are sutured to the pedicle tissue.

When the sheet form of ePTFE membrane is used, the ITA is harvested, and the anastomosis to the left anterior descending coronary artery is completed in the usual fashion. We found that wrapping the ITA while the patient is still on cardiopulmonary bypass allows complete coverage of the ITA pedicle and precise placement of the proximal and distal sutures securing the ePTFE material to the pedicle.

After good hemostasis of the ITA pedicle has been achieved, the membrane is cut to the appropriate length, ie, long enough to be near the origin of the ITA from the subclavian artery and within 1 cm of the anastomosis to the left anterior descending artery. The membrane is wrapped around the ITA and secured with silver clips. The membrane is then attached to the pedicle with proximal and distal sutures (Fig 1). Careful attention to placement of the wrapped pedicle medial to the lung and as far lateral as possible should provide protection and ensure that no kinking or distortion of the ITA occurs.

View larger version (20K): [in this window] [in a new window]   Fig 1. Expanded polytetrafluoroethylene membrane wrapped around the internal thoracic artery pedicle and secured with silver clips and sutures.

	Comment

Top Footnotes Abstract Introduction Technique Comment References

 
Kaan and associates [2] and Zehr and associates [3] conducted controlled experimental studies of ePTFE membranes used to wrap the ITA in goats and pigs, respectively. Both investigations included resternotomy and assessment of the wrapped vessels. At reoperation 6 months after the wrapping procedure, Kaan and associates [2] observed that wrapped arteries were free of adhesions, whereas nonwrapped arteries had severe adhesion formation. There were no histologic differences between the wrapped arteries and those of controls. One of the 12 wrapped arteries was occluded, but the authors attributed the thrombus to surgical technique. Zehr and associates [3] performed resternotomy 3 months after one ITA in each of six pigs was wrapped with an ePTFE membrane and the other ITA was left unwrapped. In all six animals with unwrapped ITA grafts, there were severe adhesions between the chest wall, myocardium, and grafts. In the pigs with the ePTFE membranes, the wrapped ITAs were easy to identify, and there were no adhesions between the membranes and surrounding tissue. There was no evidence of cellular infiltration, disruption, or contraction of the membranes. Zehr and associates observed that the ePTFE membrane could not be cut or damaged by electrocautery.

Zacharias [4] used an externally supported ePTFE vascular graft to wrap the right ITA pedicle in 28 patients. There were no complications related to use of the ePTFE. In six patients who later had cardiac catheterization for recurrent symptoms, the wrapped ITAs were found to be patent. There were no reoperations in that series.

Although the experience described by Zacharias appeared promising, Zehr [5] pointed out that the formulation of ePTFE used to make vascular grafts is inappropriate for wrapping ITAs. Expanded polytetrafluoroethylene has a node-and-fibril structure, with air-filled spaces between the nodes and fibrils. The larger the spaces, the greater the tissue infiltration into them over time. The ePTFE that is used in externally supported vascular grafts has relatively large (30-µm) spaces that allow fibrous tissue incorporation. As Zehr noted, this characteristic is not useful in situations in which adhesions are to be avoided, such as reoperations for cardiothoracic disease. The membrane form of ePTFE is more appropriate in these situations because the air spaces in it are less than 1 µm, and this closed microstructure should inhibit tissue attachment and adhesions. We (like Zehr) use only the low-porosity form of ePTFE to wrap the ITA of patients.

Dion [7] used ePTFE to wrap the right ITA crossing the midline for anastomosis to the left anterior descending arterial system, which offers protection and ease of identification at reoperation.

Since 1993, Michael Strong (personal communication, July 1998) has wrapped the left and right ITAs and gastroepiploic artery in 89 patients. In one patient, a sternal wound infection developed. At sternal debridement and repair, the ePTFE was removed, with a good result.

Because of the high risks associated with injury of a patent ITA graft, we now routinely use protective ePTFE membrane wrapping of the ITA pedicle during the initial bypass operation in all patients under 70 years of age, to facilitate identification of the pedicle at potential reoperation. The ePTFE is nonconductive and prevents injury by electrocautery during subsequent dissection. We observed no complications related to the use of the ePTFE membrane. Assessment of its effectiveness in preventing injury to the ITA will require large, long-term studies that follow up patients to reoperation.

	Footnotes

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¹ Dr Vaughn is a consultant to W.L. Gore & Associates, Inc., Flagstaff, Arizona.

	References

Top Footnotes Abstract Introduction Technique Comment References

 

1. Coltharp W.H., Decker M.D., Lea J.W., IV, et al. Internal mammary artery graft at reoperation: risks, benefits, and methods of preservation. Ann Thorac Surg 1991;52:225-229.[Abstract]
2. Kaan G.L., Smedts F., Van Son J.A.M., et al. Prevention of adhesion formation around the internal mammary artery pedicle by Gore-Tex surgical membrane; an experimental study in goats. Eur J Cardiothorac Surg 1993;7:81-83.[Abstract]
3. Zehr K.J., Lee P.C., Poston R.S., Gillinov A.M., Hruban R.H., Cameron D.E. Protection of the internal mammary artery pedicle with polytetrafluoroethylene membrane. J Card Surg 1993;8:650-655.[Medline]
4. Zacharias A. Protection of the right internal mammary artery in the retrosternal position with stented grafts. Ann Thorac Surg 1995;60:1826-1828.[Abstract/Free Full Text]
5. Zehr K.J. Protection of the retrosternal right internal mammary artery with stented grafts. Ann Thorac Surg 1997;63:297.[Free Full Text]
6. Blanche C., Santibanez-Gallerani A. Technique to protect the internal mammary artery pedicle. Ann Thorac Surg 1995;60:1824-1825.[Abstract/Free Full Text]
7. Dion R. Complete arterial revascularization with the internal thoracic arteries. Operative techniques in cardiac and thoracic surgery. Vol. 1, No. 1. Philadelphia. Pennsylvania: WB Saunders, 1996:84-107.

This article has been cited by other articles:

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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): Cecil C. Vaughn Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vaughn, C. C. Search for Related Content PubMed PubMed Citation Articles by Vaughn, C. C.