Morphologic Observations in Coronary Arteries, Aortocoronary Saphenous Vein Bypass Grafts, and Infant Aortae Following Balloon Angioplasty Procedures

Morphologic comparison of atherosclerotic lesions in native coronary arteries and saphenous vein graphs with intracoronary angioscopy in patients with unstable angina

BACKGROUND

Coronary vein grafts develop accelerated atherosclerosis after aortocoronary bypass surgery. Previous pathologic studies have suggested that the morphologic appearance of atherosclerotic lesions in saphenous vein grafts may have subtle differences compared with those of native coronary arteries and may be more prone to disruption and thrombus formation. However, a comparative in vivo assessment of the angioscopic morphology differences between these two types of vessels has not been reported previously. We compared the angioscopic lesion morphology of native coronary arteries and saphenous vein grafts in patients with unstable angina.

METHODS AND RESULTS

Percutaneous coronary angioscopy was performed in 60 consecutive patients with unstable angina. Plaque color, texture, friability, and the presence of atherosclerotic plaque ulceration or intracoronary thrombus were noted in the culprit lesion. The culprit lesion was located in native coronary arteries in 42 (70%) patients and in a saphenous vein graft in 18 (30%) patients. There were no significant differences in age, sex, and coronary risk factors including tobacco use, hypertension, hypercholesterolemia, or diabetes mellitus between the two populations. There were also no significant differences between the two groups in terms of plaque color, surface texture, or the incidence of complex plaque morphology (plaque ulceration and intracoronary thrombosis). Loosely adherent, friable plaque, detected by angioscopy, was absent in native coronary arteries and was present in 44% of the saphenous vein grafts (p < 0.0001).

CONCLUSIONS

The results of our angioscopic study indicate that other than a high incidence of plaque friability in vein grafts, the surface morphology of culprit lesions in unstable angina patients is quite similar for saphenous vein grafts and native coronary arteries.

Balloon angioplasty for the treatment of lesions in saphenous vein bypass grafts

OBJECTIVES

The purpose of this review is to assess the value and limitations of balloon angioplasty for the treatment of saphenous vein bypass graft obstructions. The potential efficacy of new interventional techniques is discussed.

BACKGROUND

Treatment of ischemia due to saphenous vein bypass graft obstructions poses a difficult problem that will be encountered more often as the pool of surgically treated patients continues to accumulate. Reoperation is technically demanding and is associated with high mortality and morbidity rates. Balloon angioplasty may provide a suitable alternative.

METHODS

The review proposes a classification of patients with attempted saphenous vein graft angioplasty according to expected early and late outcome based on the data obtained from the relevant published data and personal experience.

RESULTS

Angioplasty of a nonocclusive obstruction in a saphenous vein bypass graft has an initial success rate of approximately 90% and is a safe procedure (procedural death rate < 1%, myocardial infarction rate < 4%). The overall average restenosis rate is 42%. Surgical standby is limited and technically difficult. Angioplasty of chronic total occlusions in old grafts is associated with poor initial and long-term results. The long-term clinical results are unfavorable because of the continuing progression of disease in nontreated vein graft segments and native coronary arteries, in addition to the high restenosis rate. New techniques, although promising, have shown neither better initial results nor reduction of restenosis. Stent placement may be useful in longer graft lesions containing friable material.

CONCLUSIONS

Patients may be classified into three groups according to expected early and late outcome on the basis of 1) unfavorable graft anatomy, 2) risk of cardiogenic shock in event of acute graft closure, and 3) age of grafts. The three groups are 1) those with an initial high success, low procedural risk and low restenosis rate; 2) those with an initial high success but high procedural risk and moderate to high restenosis rate; and 3) those with a low success, high risk and high restenosis rate. Balloon angioplasty to treat lesions in venous bypass grafts should be considered a palliative procedure, not a long-term solution, for ongoing progression of coronary artery and vein graft disease. The induced high restenosis rate remains a significant problem.

Balloon angioplasty of aortocoronary saphenous vein bypass grafts: a histopathologic study of six grafts from five patients, with emphasis on restenosis and embolic complications

Among 103 patients undergoing percutaneous transluminal balloon angioplasty of obstructed aortocoronary saphenous vein bypass grafts at the Mayo Clinic, six grafts from 5 patients were available for histopathologic examination. The interval from graft insertion to angioplasty ranged from 5 to 105 months and that from angioplasty to graft excision ranged from 6 h to 24 months. Angioplasty produced intimal fissures in three grafts initially obstructed by intimal fibromuscular proliferation. Healing and restenosis resulted from filling of lacerations with fibrocellular tissue and apparently also from restitution of muscular tone. In two of three grafts initially narrowed by atherosclerosis, balloon angioplasty cause extensive plaque rupture and restenosis resulted from extrusion of plaque debris and secondary luminal thrombosis. In the third graft, angioplasty produced no distinct lesions and late restenosis was due to progressive atherosclerosis of the vein graft. Atheroembolization was observed in both patients with plaque rupture and was associated with reoperation in one and death in the other. In conclusion, the results derived from six saphenous vein bypass grafts subjected to balloon angioplasty indicate that restenosis may result from intimal fibrocellular proliferation, thrombosis, restitution of muscular tone and progressive atherosclerosis. Symptomatic atheroembolization may occur in grafts greater than 1 year old.