Crossed Double Internal

Mammary-to-Coronary Artery Grafts Indications, Techniques, and Results Alexander S. Geha, MD

\s=b\Crossed double internal mammary (IMA)-coronary artery grafts (the left to the left anterior descending artery [LAD], the right to a diagonal or marginal coronary branch) were used without mortality and with excellent functional results in 36 patients requiring separate grafts to these vessels (22% of patients undergoing coronary revascularization). Flows were 70\m=+-\9 ml/min in the left and 50\m=+-\7 ml/min in the right IMA, respectively. All revisualized grafts remained patent. The location and direction of the LAD and of diagonal and marginal branches allow excellent alignment of these shorter and wider double IMA grafts. The left IMA is the graft of choice for the LAD, and the right IMA is the choice for a high diagonal or early arising marginal branch that requires an additional separate graft. The right IMA is not satisfactory for right coronary or LAD bypass. (Arch Surg 111:289-292, 1976)

revascularization by Myocardial widely arteries

direct grafting of obstructed coronary has become well-es¬ tablished and accepted in the surgical manage¬ ment of coronary artery occlusive disease. Candidates for the procedure are patients with anginal syndromes, hemodynamically significant proximal occlusions of one or more major coronary arteries with relatively open distal vessels, and reasonable left ventricular contractility. The most commonly used bypass conduit has been the autoge¬ nous aortocoronary saphenous vein graft (SVG). However, a substantial early (two weeks) and late (one year) postop¬ erative occlusion rate of SVG is observed, thus decreasing the benefits intended from the operation. Clinical and ex¬ perimental observations indicate that coronary bypass with internal mammary artery (IMA) grafts achieves bet¬ ter patency than with SVGs.1-2 The left IMA has been commonly used by proponents of IMA grafting to bypass lesions in the left anterior descending coronary artery (LAD), and initial satisfactory experience with this graft has been extended to the right IMA. Recently, Mills and Ochsner3 reported 43 double IMA-coronary bypass grafts Accepted

for publication Sept 23, 1975. From the Department of Surgery, Washington University School of Medicine, St Louis, and the Division of Thoracic and Cardiovascular Surgery, Jewish Hospital of St Louis. Dr Geha is now with the Section of Thoracic and Cardiovascular Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Conn. Reprint requests to Section of Thoracic and Cardiovascular Surgery, Yale University School of Medicine, 333 Cedar St, New Haven, CT 06510 (Dr

Geha).

in their series, and Barner4 described a well-documented series of 100 patients in whom this operation was per¬ formed. Both groups report anastomosing the left IMA to the LAD most commonly, and using the right IMA pre¬ dominantly to graft the right coronary artery (RCA); less frequently, they graft the right IMA to the LAD and the left IMA to the left circumflex coronary artery (LCF). Because of a vein graft patency rate of 84% on angi¬ ographie study two weeks after surgery in our first 85 pa¬ tients, we have used IMA grafts whenever possible as of January 1973 to eliminate proximal anastomoses, achieve an equal size match between graft and recipient artery, and to try to achieve higher patency rates.2 Double IMA grafts were used in 42 of our 157 patients in whom IMA grafts were performed. However, the right IMA graft flows observed in the first six patients in whom the right IMA was anastomosed to the RCA or LAD were less than anticipated from the size and anatomy of the recipient coronary arteries (Fig 1). We have therefore abandoned the use of right IMA grafts to these two vessels, and have reserved the right IMA for grafting a high diagonal or early arising marginal circumflex vessel when such a ves¬ sel needs a separate graft (Fig 2). The left IMA is used to graft the LAD. The purpose of this article is to describe the rationale and indications for this crossed double IMA graft approach, the particular technical aspects related to it, and the results obtained in the 36 patients in whom it has been used. Rationale and Indications

The RCA is often involved with lesions beyond the marginal branch. It is also preferable to graft the RCA in the area of the crux, as close to its two major ter¬ minal branches as possible, in order to provide blood flow directly to these branches that supply part of the left ven¬ tricular myocardium. In order for the right IMA to reach the region of the crux, it has to be mobilized beyond the fifth intercostal space, where its lumen becomes definitely narrower than, and discrepant with, that of the recipient RCA. Some have utilized the right IMA as a free graft from the aorta to the RCA,4-5 but this results in losing some of the advantages of the native right IMA, which arises from a natural ostium and has an intact nerve and blood supply. The LAD is often involved by obstructive le¬ sions well into the middle of its course toward the apex of acute

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Uncrossed

Right

IMA (to RCA or lad)

6 Patients Mean Flow 32 + 7 ml/min.

Crossed

Right IMA

36 Patients Mean Flow 50 t 7 ml/min.

Fig 2.—Diagrammatic sketch showing crossed double IMA graft. Each graft aligned with recipient artery. Right IMA graft usually crosses behind left graft.

to RCA or Fig 1 .—Left, Diagrammatic sketch showing excessive length of right IMA graftwhich graft LAD, resulting in small caliber of graft at point of anastomosis. Note angle at enters LAD. Right, Shorter graft length required when right IMA anastomosed to early arising marginal branch of LCF or diagonal branch of LAD; higher flows are observed. because of injury to one IMA during the dissection in one case and the heart and needs grafting beyond such lesions. If the because of the small diameter of the IMA in the other. Thus, the right IMA were to reach this region of the LAD, a long crossed double IMA graft approach was indicated in about 22% of lu¬ an area down where the to segment must be mobilized the undergoing patients coronary revascularization. The Table men again becomes small. In addition, the right IMA shows the number of grafts performed in each of the 36 patients graft will have to enter the LAD at an angle (Fig 1) who had crossed double IMA grafts. Two thirds of them required rather than be aligned with it. A left IMA graft into the one or two additional SVGs to achieve revascularization. Five of LCF or its posteriorly located marginal branches also re¬ these 36 patients had unstable angina characterized by inter¬ quires a change of direction, and if the endothoracic as¬ mittent resting chest pain that persisted more than 24 hours despite in-hospital medical therapy and was accompanied by elecpect of the left IMA is apposed to the epicardial surface of trocardiographic changes representative of ischemia, but without the heart, torsion of the left IMA may result. The crossed of better takes IMA enzyme changes." double advantage graft approach and the of the left the LAD with IMA graft alignment Technique right IMA graft with the diagonal or early arising mar¬ of each IMA is measured at the site of diameter The external ginal branches, without torsion, and requires less length intended transection before the vessel is handled in order to avoid of each graft. This results in a larger caliber of each IMA spasm, and the IMA is used if its diameter is equal to or exceeds at the anastomosis. The indications for this approach are the angiographically estimated lumen of the recipient coronary necessarily limited to situations in which the distribution artery. The IMA is then dissected from the chest wall on a pedicle of coronary lesions requires separate grafts into the LAD by means of electrocautery without hemostats, ties, or clips, pay¬ and a high diagonal branch of it or an early arising mar¬ ing special attention to division of all branches up to the origin of the the vessel from the subclavian artery.1-2 After administration of branch of LCF. ginal heparin sodium, the IMA graft is transected at the intended site SUBJECTS AND METHODS of anastomosis, and the trimmed distal end of the graft is spatulated along its endothoracic aspect and gently calibrated with During the two-year period from April 1973 to March 1975, 42

patients received double IMA-coronary grafts. These grafts were not crossed in the first six patients. Of these, three had right IMA-

to-RCA and left IMA-to-LAD anastomoses, and another three had right IMA-to-LAD and left IMA-to-LCF grafts. The remaining 36 patients (28 male, eight female), ranging in age from 36 to 70 years, received crossed double IMA grafts and have been operated on since July 1973, a period during which a total of 168 patients underwent coronary revascularization without combined valvular replacement. Crossed double IMA grafts were planned in another two patients, not included in this series, but were not performed

probes.

Free

pulsatile

flow from the transected end is also

mea¬

sured; if the flow is less than 100 ml/min, 0.5 ml of a dilute papav¬

erine hydrochloride solution is instilled into the graft and allowed to stay for approximately ten minutes before the measurement is repeated. This step usually results in a free flow between 200 and 300 ml/min. The IMA graft is rejected if the free flow does not ex¬ ceed 100 ml/min after instillation of papaverine. The technique of cardiopulmonary bypass and performance of anastomoses have been described elsewhere.2 Using polypropylene suture material, which is characterized by a low coefficient of fric-

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Indications for Operation and Number of Grafts Required in 36 Patients With Crossed Double Internal Mammary Artery (IMA) Grafts

Procedure, No. of Grafts Two IMA grafts only Two IMA grafts + one SVG* Two IMA grafts + two SVGs Total *

Saphenous

No. of Patients with Angina

Total No·

,_«_, Stable Unstable

Patients

10 19 2 31

2

1 2 5

(%)of 12(33) 20(56) 4(11) 36(100)

vein graft.

anastomoses are constructed with a single suture, with¬ out approximating the graft to the coronary artery until all su¬ tures are in position (Fig 3), thus offering excellent visualization for an accurate anastomosis with increased speed. The anasto¬ mosis is probed in both directions just prior to its completion. Op¬ tical loupes of 3.5 are used. The pedicles are sutured to the epicardium near the anastomoses to avoid tension and angulation at

tion, the

the anastomoses. The right IMA graft is brought behind the left IMA graft and usually crosses cephalad to the aortic perfusion cannula. When SVGs to additional obstructed coronary arteries are required, they are performed prior to the IMA graft-to-coro¬ nary artery anastomoses and usually lie beneath the IMA grafts to prevent tension on the IMAs. The pedicles are carefully in¬ spected for any bleeding from the side branches of the IMAs. Mean graft blood flow is measured by an electromagnetic squarewave flowmeter 30 to 60 minutes after discontinuation of cardiopulmonary bypass, when the hemodynamic status of the patient has stabilized. Details of the postoperative care and early and late postoperative follow-up are the same as for other patients under¬ going direct coronary revascularization; they have been described elsewhere.2

RESULTS

Postoperative Mortality and Morbidity There were no early or late deaths among the 36 pa¬ tients in this study. An additional patient, not included in this report, underwent aortic valve replacement and had crossed double IMA grafts and two SVGs for a four-cusp incompetent aortic valve and extensive coronary artery disease with small distal vessels; it was not possible to wean him off cardiopulmonary bypass after the procedure. Excessive mediastinal bleeding requiring another oper¬ ation occurred in two patients. Both had an uneventful re¬ covery. A third patient developed a severe mediastinal in¬ fection due to Serratia marcescens on the ninth postoperative day. He was treated by debridement of the sternal edges and mediastinal space and continuous irri¬ gation with an antibiotic solution. This was changed to a solution of 0.5% povidone-iodine7 two weeks later, because of continuing purulent discharge, and the drainage was then converted to an open system such as used in chronic pleural empyema. The patient made a full recovery after another bout of localized osteomyelitis of a portion of the sternum, which required debridement of that area. One patient had electrocardiographic evidence of myo¬ cardial infarction in the early postoperative period and an uncomplicated postoperative course, indicating that the infarction was of little hemodynamic significance. No late infarction has occurred in these patients.

Mean Graft Flow and

Postoperative Angiography

There was no significant difference in free pulsatile flow from the right and left IMAs. The mean values ± SEM for graft mean blood flow were 70 ± 9 ml/min for the left IMA graft to the LAD and 50 ± 7 ml/min for the right IMA graft to a diagonal or marginal branch (P < .05). All patients underwent postoperative visual¬ ization of the grafts at about two weeks after surgery, prior to discharge from the hospital, and all 72 IMA grafts were patent. Ten patients have had another late (six months to two years) postoperative angiographie study, with patency of all their IMA grafts. Functional Results

Follow-up information was available on all 36 patients by clinic visits or correspondence with the patients' pri¬ vate physicians. The functional classification system of the New York Heart Association was used in the eval¬ uation of functional results. Patients were assigned a postoperative functional classification no higher than that permitted by their exercise tolerance, even if anginal symptoms were absent. Thirty patients (83%) are in func¬ tional class 1 and asymptomatic. In comparison with their preoperative status, 35 of the 36 patients are improved, and most of them have returned to their jobs and to full

activity.

COMMENT Crossed double IMA-to-coronary artery grafts take ad¬ vantage of the anatomical location of the LAD and its

diagonal branches and early arising marginal branches of the LCF to achieve better alignment of each graft with the recipient artery and a shorter graft distance to the anastomosis. It broadens the applicability of the right IMA in direct coronary revascularization. The higher flows observed in left IMA grafts to the LAD in com¬ parison with right IMA grafts to diagonal or marginal branches are probably related to the capacity of the distal grafted bed rather than to characteristics of the grafts themselves. The flows in the crossed right IMA grafts are significantly higher (P < .01) than those observed early in our experience in right IMA grafts to the RCA or LAD. This significant difference in right IMA graft flow is prob¬ ably due to the smaller caliber of the uncrossed right IMA graft at the site of anastomosis and to possible angulation at the anastomosis of the right IMA-to-LAD grafts. Our experience with this procedure indicates that the advan¬ tages of properly selected double IMA grafts can be safely extended to patients with unstable angina who meet the anatomical criteria for the operation. This experience is characterized by lack of mortality and a relatively low morbidity. The only serious complica¬ tions were bleeding, which required a second operation in 5.5% of the patients, and the case of mediastinitis de¬ scribed above. Barner4 reported an early postoperative mortality of 8% in his series of 100 uncrossed double IMA grafts, a 12% incidence of reoperation for bleeding, and four of his patients developed mediastinal infection that eventually led to a late death in one. Mediastinal infection

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Fig 3.—Details of graft-to-coronary anastomosis. Trimmed IMA is spatulated along its endothoracic aspect. Anastomosis con¬ structed with one continuous double-armed (N-1, needle 1; N-2,

needle 2) suture of polypropylene while two vessels held apart. Suture is tightened, and anastomosis probed just before comple¬ tion.

has been attributed to possible effects of devascularizing patency of the IMAs. Its mortality and morbidity are com¬ both sides of the sternum with bilateral IMA dissection. parable to those associated with the use of SVGs exclu¬ Our patient who developed this complication represents sively, and the angiographie and functional results are ex¬ the only case of mediastinal infection that we have en¬ cellent. A larger experience will be required to clarify countered in our personal experience with over 250 pa¬ whether or not it is associated with a potentially greater tients undergoing coronary revascularization. frequency of mediastinal infection. This approach defines the indications for use of the This investigation was supported in part by research grant 5 R01 HL13088-06 from the National Heart and Lung Institute. right IMA to exploit the advantages of apparent better References 1. Green GE: Internal mammary artery-coronary anastomosis: Three\x=req-\ year experience with 165 patients. Ann Thorac Surg 14:260-269, 1972. 2. Geha AS, McCormick JR, Krone RJ, et al: Selection of coronary bypass: Anatomic, physiologic and angiographic considerations of vein and mammary artery grafts. J Thorac Cardiovasc Surg 70:414-431, 1975. 3. Mills NL, Ochsner J: Technique of internal mammary-coronary artery bypass. Ann Thorac Surg 17:237-246, 1974. 4. Barner HB: Double internal mammary-coronary bypass. Arch Surg 109:627-630, 1974.

5. Loop FD, Spampinato N, Cheanvechai C, et al: The free internal mammary artery bypass graft. Ann Thorac Surg 15:50-55, 1973. 6. Geha AS, Baue AE, Krone RJ, et al: Surgical treatment of unstable angina by saphenous vein and internal mammary artery bypass grafting. J Thorac Cardiovasc Surg, to be published. 7. Thurer RJ, Bognolo D, Vargas A, et al: The management of mediastinal infection following cardiac surgery: An experience utilizing continuous irrigation with povidone-Iodine. J Thorac Cardiovasc Surg 68:962-968, 1974.

Editorial Comment Utilization of the internal mammary arteries for revasculariza¬ tion of the native coronary circulation has proved to be a major advance in cardiac surgery. Since the initial descriptions of this operative technique, modification and refinements have made the operation a routine procedure in many centers. Most surgeons have not used the right internal mammary artery because it did not seem satisfactory for either the right coronary or the distal part of the left anterior descending artery, for the reasons de¬ scribed by Dr Geha. Dr Geha's concept of crossing the mammary

artery grafts is a clever one, and I think it represents a useful technical refinement that provides for more effective coronary re¬ vascularization. His results are certainly superb, and his careful assessment of intraoperative flows as well as postoperative pa¬ tency emphasizes the scientific merit of this technique. I suspect it will find wider utilization in the future. John J. Collins, Jr, MD Boston

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