Accelerated intimal hyperplasia in aortocoronary internal mammary vein grafts in minipigs.

BACKGROUND: More than 50% of aortocoronary saphenous vein grafts are occluded 10 years after surgery. Intimal hyperplasia is the initial critical step in the progression toward occlusion. Internal mammary veins, which are physiologically prone to less hydrostatic pressure, may undergo an accelerated progression to intimal hyperplasia and thus be suitable for investigation of the mechanisms of aortocoronary vein graft disease. METHODS: Six minipigs underwent aortocoronary bypass grafting using standard cardiopulmonary bypass and cardioplegic arrest. Mammary vein were grafted in a reversed manner from ascending aorta to left anterior descending coronary artery (LAD). The proximal LAD was ligated, rendering the anterior left ventricle vein graft-dependent. Minipigs were killed after 4 weeks, and vein grafts were harvested. Histological and immunohistological investigation were performed with respect to morphometric analysis, endothelial damage/dysfunction (v-Willebrand-factor (vWF)), smooth muscle cells (alpha-smooth actin) and proliferation rate (proliferation marker Ki 67). RESULTS: Mean intimal area of vein grafts was increased compared to ungrafted mammary veins. Intimal hyperplasia in vein grafts was characterized by massive accumulation of smooth muscle cells with a high proliferation rate and endothelial perturbation. Significant (p = 0.001) intimal hyperplasia of the grafted mammary vein compared to the ungrafted mammary vein was found. These changes were absent in ungrafted mammary veins. CONCLUSION: The present study demonstrates a pig model of aortocoronary vein graft intimal hyperplasia which is characterized by an accelerated progression within internal mammary veins. The model is suitable to investigate the pathophysiology of aortocoronary vein graft intimal hyperplasia as well as therapeutic approaches.

[Adequate venous autoplasty in severe superior vena cava syndrome]. / Adekvatnaia autovenoznaia plastika pri tiazhelom sindrome verkhnei poloi veny.

Eleven patients underwent plastic operations on the superior vena cava (SVC) in its severe occlusion. The SVC syndrome was caused by malignant tumors of the right lung and mediastinum in 9 patients, lymphogranulomatosis in one patient, and by chronic fibrous mediastinitis in another patient. The SVC and its main branches were replaced by a multisegmental graft (lineal or bifurcation) of autogenous vein formed by parallel stitching together of 3-5 longitudinally cut segments of the vena saphena magna. Venous drainage was adequate and the graft remained unobstructed for a long time due to the anatomical conformity of the graft to the SVC and the equal diameters of the joined vessels. The immediate and late-term (3 to 26 months) results of plastics with a multisegmental graft or autogenous vein were good.