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Ann Thorac Surg 1997;64:451-453
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Modified T Graft for Triple-Vessel Disease

Department of Cardiothoracic Surgery, Westmead Hospital, Westmead, Sydney, Australia

Accepted for publication February 26, 1997.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Background. Arterial coronary bypass grafts are used in younger patients due to the limited long-term patency of saphenous vein grafts. Using both internal thoracic arteries in a T graft configuration allows complete myocardial revascularization without the need for alternative conduit.

Methods. A prospective analysis of 75 consecutive patients with triple-vessel disease who were aged less than 66 years and who had a left ventricular ejection fraction greater than 0.50 was performed from November 1994 to November 1995. Seventy-three patients underwent myocardial revascularization using a modified T graft technique using both internal thoracic arteries. Postoperative cardiac enzyme and electrocardiographic analyses were performed along with routine surgical and cardiologic review to March 1996.

Results. There were no deaths or perioperative myocardial infarcts, and there was no sternal dehiscence due to infection. Five patients had recurrent angina and underwent repeat angiography. Three were treated by single coronary artery angioplasty and 2 with medical therapy.

Conclusions. A modified T graft revascularization of patients selected by the protocol used in this study is safe.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Saphenous vein grafts undergo a degenerative change in the intermediate to long term that ultimately limits graft patency. As a result there has been a trend to use arterial grafts in younger patients. The use of routine in-situ or free internal thoracic artery (ITA) techniques in triple-vessel disease has provided inadequate conduit length for full myocardial revascularization with ITAs alone. It has been shown that by attaching the free right ITA (RITA) to the in-situ left ITA (LITA) as a T graft, complete revascularization of the myocardium becomes possible [1–3]. In practice this technique gives an extra 10 cm of length to the RITA.

The aim of this study was to demonstrate the safety of a patient selection protocol for those with triple-vessel disease undergoing full myocardial revascularization using bilateral ITAs with a modified T graft technique.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
A prospective analysis of all patients with triple vessel disease, ejection fraction greater than 0.50, and age less than 66 years was carried out between November 1994 and November 1995. Patients were excluded if they had acute coronary insufficiency, had a high take-off posterior descending coronary artery requiring independent grafting, or were receiving systemic steroids.

The procedure was performed via a median sternotomy, and both ITAs were harvested with cautery using a skeletonizing technique. The free RITA was taken down first and prepared separately by the assistant with in-traluminal papaverine in Ringer's solution and titanium clips to the branches. The length of the RITA was measured so that if there was clearly more than adequate length the distal end could be trimmed accordingly. It was not used beyond the bifurcation. The in-situ LITA was harvested simultaneously, and the patient then was heparinized.

Routine cardiopulmonary bypass and antegrade cold blood cardioplegia were used in all cases. The posterior descending or distal right coronary artery graft was performed first using the beveled distal end of the free RITA as an end-to-side anastomosis in parallel. Lateral wall anastomoses were then performed in a side-to-side perpendicular (diamond) fashion using the RITA. The T anastomosis was then performed between the RITA and the in-situ LITA end-to-side in parallel at the level of the lateral pericardotomy. This anastomosis was performed as proximal on the LITA as possible to allow good lie of the RITA. After completion of the T anastomosis, the anterior wall anastomoses were performed. All anastomoses were performed with a single continuous 7/0 polypropylene suture, usually under 2x magnification.

A left extrapericardial fat pad (mobilized before cardiopulmonary bypass) was secured to the anterior pericardotomy, and the sternum was closed with a minimum of three figure-8 wires.

Cardiac enzyme analyses were performed on all patients at approximately 4, 8, and 12 hours postoperatively. Electrocardiograms were performed immediately postoperatively and at 1, 2, and 5 days. Surgical review was at 5 weeks and thereafter routine follow-up was undertaken by the referring cardiologists. Exercise stress testing was performed according to the practice of the cardiologist.

Repeat coronary angiography was performed electively on 1 patient (Fig 1) and in others according to clinical indications. Follow-up by a questionnaire to the cardiologists was carried out in March 1996.

View larger version (94K): [in this window] [in a new window]   Fig 1. . Coronary angiogram by injection of contrast into the left internal thoracic artery, in the right anterior oblique view.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

Two patients received supplemental vein grafts after initial separation from cardiopulmonary bypass. In 1 case this was performed because of electrocardiographic changes of inferior ST elevation, with satisfactory hemodynamic parameters. The other was for low cardiac output in a patient with preoperative unstable angina. This patient required an intraaortic balloon pump and inotropic support in the immediate postoperative period. Both of these patients subsequently made uneventful recoveries. Complete revascularization using ITAs only was therefore performed in 71 patients (97%). Two patients required exploration for bleeding. Serial electrocardiograms and cardiac enzyme analyses performed on all patients revealed no evidence of perioperative myocardial infarction. Superficial wound infection occurred in 1 patient. Two patients with postoperative bronchospasm had mechanical sternal dehiscence at day 5, and required rewiring only.

All patients were free of angina at the 5-week visit. Cardiology follow-up was complete in 64 patients in the series (87%). Thirty-nine patients underwent exercise stress tests, of which 3 were considered positive, but the patients were asymptomatic and were not investigated further. Five patients had recurrence of angina and underwent repeat angiography. In 1 patient all anastomoses were patent, and it was assumed that a diseased vein graft not ligated at the T graft operation had undergone late occlusion. The other 4 patients, 2 of whom were female with low body surface area, had occlusion of portions of the free RITA conduit. Three of these patients underwent angioplasty to the relevant native coronary artery.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The LITA, when anastomosed to the left anterior descending artery, has proved to be the superior bypass conduit in coronary artery bypass grafting, with high patency rates beyond 10 years and improved survival [4]. It is considered that the RITA also offers high long-term patency and that this is likely to be reflected in reduced angina recurrence and late mortality [5, 6]. Aortocoronary vein grafts are associated with acceleration of existing native vessel disease apart from the well-described accelerated graft disease, when compared with ITA grafts [7]. This is due to the matched flow rate offered by the ITA. The T graft configuration is designed to augment native coronary flow rather than provide entire myocardial perfusion via the in-situ LITA, and may be the most appropriate method of limiting the progression of native disease.

Patients were included in the series if less than 66 years of age, to benefit from the increased long-term patency offered by ITA grafts. The length of the free RITA is limited and may be inadequate to reach from the posterior descending artery to the LITA in the presence of left ventricular dilatation. Adequate length should be available if the ejection fraction is greater than 0.50, so this was used as a selection criterion in this series. A posterior descending artery with a high take-off requiring independent grafting precluded patients from being included in the study on the basis of RITA conduit length. Systemic steroid therapy was considered a significant risk factor for suppurative sternal dehiscence. Obesity, diabetes, obstructive airways disease, low body surface area, and severity of coronary artery disease did not exclude patients from the series.

The distal anastomosis was performed first as it allows the run-off to be tested. Cardioplegia can be administered down the graft if necessary. The ITA-to-ITA anastomosis is performed in a motionless field with the heart arrested, which allows an accurate and efficient technique. This anastomosis can be tested by LITA probing if necessary.

A skeletonizing technique was used in harvesting the ITAs, offering a theoretic advantage in terms of reduced sternal devascularization [8, 9], as was a retrosternal fat pad. With these techniques we do not consider diabetes a significant risk factor for sternal complications in patients less than 66 years of age.

The side-to-side anastomoses with the RITA are perpendicular and those with the LITA are parallel. In perpendicular anastomoses the length of the coronary arteriotomy must not exceed the diameter of the ITA. The small arterotomies should be made in a relatively healthy part of the coronary artery so that the anastomotic opening is not impaired by the rigidity of atheromatous disease. The question of bypassing low-grade stenoses has been addressed by other authors [2, 7]. Consideration must be given to competitive flow against full collateralization of the coronary system.

We have used the T graft configuration in other situations including double-vessel disease, in patients older than 66 years, and in those with poor left ventricular function, but on a selective basis. We had a low threshold for vein graft augmentation early in the series but continue to believe this to be a safe option when complete revascularization is in doubt.

We believe that the full T graft revascularization technique used in this group of patients is the procedure of choice and should be performed in a routine, nonselective manner, according to the protocol above.

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We thank Dr Donald Ross (Sydney, Australia) for his demonstration of this modification of the T graft technique.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Address reprint requests to Dr Paterson, Department of Cardiothoracic Surgery, Westmead Hospital, Hawkesbury Rd, Westmead, NSW 2145, Australia.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

1. Sauvage LR, Wu HD, Kowalsky TE, et al. Healing basis and surgical techniques for complete revascularization of the left ventricle using only the internal mammary arteries. Ann Thorac Surg 1986;42:449–65.[Abstract]
2. Tector AJ, Amundsen S, Schmahl TM, Kress DC, Peter M. Total revascularization with T grafts. Ann Thorac Surg 1994;57:33–9.[Abstract]
3. Barra JA, Bezon E, Mansourati J, Rukbi I, Mondine P, Youssef Y. Reimplantation of the right internal thoracic artery as a free graft into the left in situ internal thoracic artery (Y procedure). J Thorac Cardiovasc Surg 1995;109:1042–8.
4. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal mammary artery graft on 10-year survival and other cardiac events. N Engl J Med 1986;314:1–6.[Abstract]
5. Fiore AC, Naunheim KS, McBride LR, et al. Fifteen-year follow-up for double internal thoracic artery grafts. Eur J Cardiothorac Surg 1991;5:248–52.[Abstract]
6. Galbut DL, Traad EA, Dorman MJ, et al. Seventeen year experience with bilateral internal mammary artery grafts. Ann Thorac Surg 1990;49:195–201.[Abstract]
7. Cosgrove DM, Loop FD, Saunders CL, Lytle BW, Kramer JR. Should coronary arteries with less than fifty percent stenosis be bypassed? J Thorac Cardiovasc Surg 1981;82:520–30.[Medline]
8. Parish MA, Asai T, Grossi EA, et al. The effects of different techniques of internal mammary artery harvesting on sternal blood flow. J Thorac Cardiovasc Surg 1992;104:1303–7.[Abstract]
9. DeJesus RA, Acland RD. Anatomic study of the collateral blood supply of the sternum. Ann Thorac Surg 1995;59:163–8.[Abstract/Free Full Text]

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This Article Abstract 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): Ian A. Nicholson Hugh S. Paterson Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nicholson, I. A. Articles by Paterson, H. S. Search for Related Content PubMed PubMed Citation Articles by Nicholson, I. A. Articles by Paterson, H. S.