Ann Thorac Surg 2005;80:1530-1531
© 2005 The Society of Thoracic Surgeons
How to do it
A Technique for Salvaging a Critical Internal Mammary Artery Bypass Graft Damaged During Resternotomy
Sridhar Rathinam, FRCS
a
,
Ramesh Gohil, ACP
b
,
James Galea, FRCS
a
,
Bruce E. Keogh, FRCS
a
,
*
a Department of Cardiothoracic Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham, Edgbaston, Birmingham, United Kingdom
b Department of Perfusion, Queen Elizabeth Hospital, University Hospitals Birmingham, Edgbaston, Birmingham, United Kingdom
Accepted for publication April 20, 2004.
* Address reprint requests to Dr Keogh, Queen Elizabeth Hospital, University Hospitals Birmingham, Edgbaston, Birmingham B17 8RP, UK (Email: bruce.keogh{at}uhb.nhs.uk).
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Abstract
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Resternotomy in the presence of a patent internal mammary artery graft poses an addition hazard to the reoperation. We describe a situation in which the patent mammary artery graft to the left anterior descending artery was severed and retracted during sternal reentry for an aortic valve replacement. We illustrate a simple technique for restoring the blood supply using a coronary artery shunt.
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Introduction
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Patients with successful coronary surgery reliant on a patent internal mammary artery graft are increasingly presenting for valve surgery. Resternotomy in the presence of a patent internal mammary artery graft is an unattractive proposition, made even less attractive if the internal mammary artery lies behind the sternum or is known to be a critical conduit [1–3]. Damage or severance of such a graft early on in the operation produces bleeding followed by myocardial ischemia. Bleeding can usually be controlled, but ischemia can be problematic particularly if the adhesions are dense and bypass cannot be instituted expeditiously. If the severed graft is critical, then such an injury can prove fatal.
Intravascular coronary shunts are commonly used in coronary artery surgery on the beating heart to maintain distal perfusion and facilitate construction of the anastamosis in a bloodless field [4]. They also prevent inadvertent stitching of the back wall of the coronary artery during construction of the coronary anastamosis. We describe an important lifesaving utility of the coronary shunt in restoring flow to a graft damaged during resternotomy.
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Technique
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A 68-year-old woman was admitted electively for replacement of her calcific aortic valve. She had undergone triple coronary artery bypass grafts and inspection of the aortic valve 2 years earlier. At that time, the valve was slightly thickened but without any evidence of calcification in the leaflets and only a small spot of calcification on the valve annulus. She had subsequently become increasingly symptomatic with episodes of syncopy and angina. Investigations revealed calcific aortic stenosis with a gradient of 70 mm Hg. A repeat angiogram revealed moderate left ventricular function and a functioning internal thoracic artery graft to the left anterior descending artery and a functioning saphenous venous graft to the posterior descending artery. The saphenous vein graft to the obtuse marginal coronary artery was no longer patent, and there was no graftable native vessel in the territory.
Apart from requiring inhalers for her chronic obstructive airway disease, the patient was otherwise well and was therefore accepted for aortic valve replacement.
After resternotomy, but during early dissection of substernal adhesions, the left internal mammary artery bypass graft was divided. The cut ends of the graft retracted immediately into the fibrosis. There was a good flow in the divided mammary artery and immediate evidence of ischemia on the electrocardoigram (ECG). Attempts to free the graft and construct an end-to-end anastamosis were unsuccessful due to retraction.
While preparing for femorofemoral cardiopulmonary bypass, the perfusionist (R.G.) offered a solution. He suggested the use of an intracoronary shunt to bridge the gap between the retracted internal mammary artery ends. We used a 2-mm coronary shunt; the shunt was first introduced into the proximal end of the severed mammary artery and was secured with a fine silk suture. Good flow was seen through the shunt (Fig 1, A). The other end of the shunt was then introduced into the distal end of the severed internal thoracic artery and secured (Fig 1, B). The ECG evidence of ischemia resolved within the next few minutes with return to an isoelectric ECG.
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Fig 1. (A) A 2-mm intracoronary shunt has been attached to the proximal end of a left internal mammary artery graft severed during resternotomy. The picture illustrates excellent flow through the shunt. (B) A 2-mm intracoronary shunt has been inserted to bridge a gap between the severed ends of a left internal mammary artery graft.
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After further uneventful dissection, aortoatrial cardiopulmonary bypass was established. An aortic cross-clamp was applied, the shunt disconnected, the distal internal mammary artery graft clamped, and the heart arrested with intraaortic cardioplegia. After a routine aortic valve replacement, an end-to-end anstamosis was constructed between the distal internal mammary artery and a portion of saphenous vein. The proximal end of the saphenous venous graft was then anastamosed end to side to the preexisting saphenous vein graft to the posterior descending coronary artery. The patient's subsequent surgery and postoperative recovery were uneventful. There was no ECG evidence of a perioperative myocardial infarction or continuing ischemia.
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Comment
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Graft protection in reoperations is of prime importance; hence meticulous care needs to be taken during re-entry. However, injury to conduits is unavoidable in one's career. The management of the situation depends on the nature of the injury and the timing of the injury. If the damage is just a small hole, it can be sutured, and dissection can be carried out. If the vessel is severed, however, as in our case, then the options are to reconstruct an end-to-end anastamosis wherever feasible. When reconstruction is not feasible, then myocardium is protected by establishing cardiopulmonary bypass and administering cardioplegia. That depends on the timing of the injury during dissection. If the aorta and right atrium are exposed, then aortoatriocaval cardiopulmonary bypass is established; conversely, if dissection is not complete, femorofemoral bypass has to be established. The use of a coronary shunt in these scenarios is simple, quick, and lifesaving.
The coronary shunt is an important tool in the surgeon's armamentarium in reoperations, especially to tide one over the crisis scenarios of damage to conduits in which primary reconstruction is not possible.
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References
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- Odell JA, Mullany CJ, Schaff HV, Orszulak TA, Daly RC, Morris JJ. Aortic valve replacement after previous coronary artery bypass grafting Ann Thorac Surg 1996;62:1424-1430.[Abstract/Free Full Text]
- Hochrein J, Lucke JC, Harrison JK, et al. Mortality and need for reoperation in patients with mild-to-moderate asymptomatic aortic valve disease undergoing coronary artery bypass graft alone Am Heart J 1999;138:791-797.[Medline]
- Byrne JG, Aranki SF, Adams DH, Rizzo RJ, Couper GS, Cohn LH. Mitral valve surgery after previous CABG with functioning IMA grafts Ann Thorac Surg 1999;68:2243-2247.[Abstract/Free Full Text]
- Lucchetti V, Capasso F, Caputo M, et al. Intracoronary shunt prevents left ventricular function impairment during beating heart coronary revascularisation Eur J Cardiothorac Surg 1999;15:255-259.[Abstract/Free Full Text]
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Abstract
Introduction
