Coronary reoperations

Saphenous vein graft failure after coronary artery bypass surgery: pathophysiology, management, and future directions

OBJECTIVE

To review our current understanding of the epidemiology and pathogenesis of vein graft failure (VGF), give an overview of current preventive and interventional measures, and explore strategies that may improve vein graft patency.

BACKGROUND

VGF and progression of native coronary artery disease limit the long-term efficacy of coronary artery bypass graft surgery.

METHODS

We reviewed the published literature on the pathophysiology, prevention, and/or treatment of VGF by searching the MEDLINE (January 1, 1966-January 1, 2012), EMBASE (January 1, 1980-January 1, 2012), and Cochrane (January 1, 1995-January 1, 2012) databases. In addition, we reviewed references from the selected articles for studies not identified in the initial search. Basic science and clinical studies were included; non-English language publications were excluded.

RESULTS

Acute thrombosis, neointimal hyperplasia, and accelerated atherosclerosis are the 3 mechanisms that lead to VGF. Preventive measures include matching and quality assessment of conduit and target vessel, lipid-lowering drugs, antithrombotic therapy, and cessation of smoking. Treatment of VGF includes medical therapy, percutaneous intervention, and redo coronary artery bypass graft surgery. In patients undergoing graft intervention, the use of drug-eluting stents, antiplatelet agents, and embolic protection devices may improve clinical outcomes.

CONCLUSIONS

Despite advances in management, VGF remains one of the leading causes of poor in-hospital and long-term outcomes after coronary artery bypass graft surgery. New developments in VGF prevention such as gene therapy, external graft support, fully tissue-engineered grafts, hybrid grafts, and synthetic conduits are promising but unproven. Future efforts to reduce VGF require a multidisciplinary approach with a primary focus on prevention.

Severe deformity of a Palmaz-Schatz stent after normal surgical manipulation

This report describes a case in which normal surgical manipulation during dissection of the heart while performing a repeat revascularization procedure produced a significant deformity in Palmaz-Schatz stents previously implanted in a saphenous vein graft. The graft had shown satisfactory angiographic appearance immediately before the operation, and consideration was given to leaving it in place. Its replacement, however, prevented a major intraoperative mishap.

Long-term angiographic follow-up of normal and minimally diseased saphenous vein grafts

OBJECTIVES

We sought to ascertain the long-term fate of saphenous vein grafts known to be angiographically normal or minimally diseased 5 years after operation. This information may prove helpful in the management of such grafts at reoperation.

BACKGROUND

Patients undergoing a second coronary bypass operation frequently have one or more saphenous vein grafts that remain widely patent. It is common practice during such reoperations to replace all vein grafts that are older than 5 years, including those with little or no angiographic stenosis, because of the risk of late vein graft closure. However, the long-term behavior of these angiographically normal or minimally diseased vein grafts has not been well elucidated.

METHODS

Sixty-two patients with a total of 131 angiographically normal or minimally diseased (< 35% diameter narrowing) vein graft segments studied 6.1 +/- 2.1 years (mean +/- SD) after coronary bypass operation were identified by reviewing the cardiac catheterization records of the Veterans Affairs Medical Center, Buffalo, New York. Repeat angiography was performed on these patients 5.1 +/- 1.4 years after the initial postoperative angiogram (11.0 +/- 2.0 years after operation).

RESULTS

On restudy, 53% of the vein grafts remained normal or only minimally diseased, 18% showed moderate stenosis (35% to 69%), 8% were patent but with severe disease (70% to 99%) and 21% were totally occluded. Disease progression was similar in grafts that were previously normal compared with those that had minimal disease.

CONCLUSIONS

The long-term patency of angiographically normal or minimally diseased vein grafts is good (79% 5-year patency rate, 71% free of severe disease). The presence of minimal disease does not adversely affect long-term patency. The recommendation to replace normal or minimally diseased vein grafts during late reoperation should be reevaluated.

Repeat coronary artery bypass grafting

In 1981-1989 we performed repeat coronary artery bypass grafting on 42 men and 10 women (mean age 55 years) with angina pectoris recurring on average 27 months after the primary operation. The cause was occlusion or stenosis of vein grafts alone (59%) or in combination with progression of native coronary atherosclerosis (31%) or progression in the native circulation without graft failure (10%). Complications at the repeat operation included five lesions of the right ventricle and five lesions of patient grafts. The 30-day mortality was 3.8% (95% confidence limits 0.5-13.2%). Survival after observation averaging 2 1/2 years was 92.3% (95% confidence limits 81.5-97.9%). Angina pectoris was completely relieved after the operation in 48% of the patients, lessened in 35% and unchanged in 17%. Although repeat coronary artery bypass grafting carries heightened mortality and morbidity, and the results are less satisfactory than after first-time bypass, the operation can be worthwhile.

Reoperative cardiac surgery using a new femoral venous right atrial cannula

A new ultra-thin but nonkinkable catheter was used for transfemoral venous right atrial drainage for cardiopulmonary bypass in 35 patients undergoing reoperations for coronary artery disease (CAD) (14), valve replacement (16), combined valve and CAD (4), and left ventricular aneurysm resection (1). Adequate flow rates were obtained with these cannula of 25, 27, and 29 French diameter in all patients. This technique provided excellent drainage of the heart allowing for a decompressed heart to dissect with no bleeding or damage to patent obstructed cardiopulmonary bypass grafts. There was no mortality over perioperative myocardial infarction postoperatively.