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J Thorac Cardiovasc Surg 1994;108:1154-1155
© 1994 Mosby, Inc.

LETTERS TO THE EDITOR

Sequential internal mammary artery grafting

Department of Cardiothoracic Surgery
Manchester Royal Infirmary
Manchester, United Kingdom

To the Editor:

Sequential coronary artery grafting with the internal mammary artery (IMA) may result in narrowing of the vessel, such that the perfusion to the more distal vessel is compromised By performing the more proximal anastomosis first, the surgeon can reliably assess distal runoff and take remedial action if it is inadequate.

The left IMA is regarded as being the ideal conduit for bypassing occlusive disease of the left anterior descending (LAD) coronary system. ¹ Sequential grafting with side-to-side anastomoses is an accepted technique and is most commonly used to revascularize diagonal branches. ² Sequential grafting, however, may result in narrowing of the IMA at the site of a diagonal anastomosis, with resultant poor runoff to the LAD. Such narrowing may be caused by the kinking of the vessel or by inadvertent damage, such as a technical error when the side-to-side anastomosis is being created. If the distal anastomosis is performed first (as is our usual practice with sequential vein grafts), it is impossible to assess the distal runoff until the end of the procedure. In some cases the IMA has become occluded beyond the diagnonal anastomosis.

The following method obviates this difficulty: The IMA is skeletonized during mobilization, side branches being controlled with vascular clips (Ligaclip; Ethicon, Inc., Somerville, N.J.) or bipolar diathermy. ^{3, 4} The left pleura is left intact, if possible. The IMA is mobilized up to the left subclavian vessels and then detached at its distal end after heparinization. The artery is passed through a tunnel behind the left lobe of the thymus. ⁴

Sequential grafting is performed only if the following conditions are met: (1) the more proximal coronary vessel must be easily accessible; (2) the IMA must be of adequate length to run between the anastomoses without tension; (3) the IMA must be of adequate caliber to enable the proximal anastomosis to be executed without narrowing the lumen; and (4) the LAD must not have a critical proximal stenosis, such that adequate perfusion of the entire LAD system is totally dependent on the IMA. If these conditions are not satisfied, then the IMA is anastomosed to the LAD, and a separate vein graft is placed on the diagonal branch.

Arteriotomies are made at the selected sites in the LAD and diagonal arteries. The site for the proximal side-to-side anastomosis is selected on the IMA, and a longitudinal incision is made in the artery. This is done with the bulldog clamp placed at the distal end of the IMA, so that the artery is distended with blood. This enables the surgeon to separate the vessel more cleanly from adventitial tissue and guarantees that the back wall will not be damaged with the knife. A spurt of blood signals breaching of the lumen. The bulldog clamp is then repositioned proximally, and the IMA is emptied of blood. The incision in the IMA is extended with scissors to the desired length (about 5 mm), keeping parallel to the axis of the vessel.

A side-to-side anastomosis to the diagonal branch is then performed with a running 7-0 Prolene suture (Ethicon). Patency of the distal IMA segment can then be demonstrated by briefly releasing the bulldog clamp. If any doubt exists about the adequacy of distal runoff, a probe can be passed retrogradely from the distal end of the IMA.

The end of the IMA is then fashioned for the LAD ana stomosis, adequate length being provided to enable the vessel to lie in a smooth curve, without kinking. An end-to-side anastomosis is performed to the LAD with a running 7-0 Prolene suture.

Performing the more proximal anastomosis first offers three advantages: (1) It is technically easier, because the distal IMA segment can be swung sideways as desired to expose the vessel edges; (2) a good assessment can be made of the adequacy of flow to the distal segment; and (3) if distal runoff is inadequate, remedial action can be taken. If the IMA becomes irretrievably damaged, the distal segment can be ligated and a seperate vein graft placed on the LAD.

The most important consideration when a sequential IMA graft is being performed is to avoid compromising the perfusion to the distal vessel, usually the LAD. Performing the more proximal anastomosis first enables this goal to be reliably attained.

References

1. Tector AF, Schmahl TM, Canino VR. The internal mammary artery graft: the best choice for bypass of the diseased left anterior descending coronary artery. Circulation 1983; 68:(Suppl)II14.
   
2. McBride LR, Barner HB. The left internal mammary artery as a sequential graft to the left anterior descending system. J THORAC CARDIOVASC SURG 1983;86:703.[Abstract]
   
3. Mills L. Skeletonized internal mammary artery. Ann Thorac Surg 1988;45:468.[Medline]
   
4. Martinez MJ, Garcia-Rinaldi R, Traad EA. Minimizing internal mammary artery tension. Ann Thorac Surg 1988;46:712.
   

This Article Alert me when this article is cited Alert me if a correction is posted 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): Nicholas J. Odom Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ashraf, S. S. Articles by Odom, N. J. Search for Related Content PubMed PubMed Citation Articles by Ashraf, S. S. Articles by Odom, N. J.