In-vitro effects of cardioplegic solutions on human saphenous vein endothelium--a scanning electron microscopy study

In order to evaluate the effects of potassium cristalloid cardioplegic solutions (CPS) on the endothelial morphology, human saphenous veins were studied by scanning electron microscopy after exposure to three CPS named MKP (magnesium-potassium-procaine cardioplegia), LK (low-potassium cardioplegia), and HKA (high-potassium-albumin cardioplegia) and to their main components. Vein rings, selected from the saphenous veins sampled for graft harvesting in 63 patients undergoing aorto-coronary bypass surgery, were exposed for 30, 60, and 120 minutes to the following buffered solutions: Krebs bicarbonate (as control); MKP cardioplegia; KCl (16.0 mmol/L); MgCl2(2).6H2O (16.0 mmol/L); Procaine (0.05 mmol/L); NaCl (92.5 mmol/L); LK cardioplegia; KCl (10.0 mmol/L); Mannitol (74.3 mmol/L); Glucose (27.7 mmol/L); HKA cardioplegia; KCl (30 mmol/L). Severe endothelial lesions, consisting of diffuse disendothelialization and diffuse signs of endothelial suffering, were induced by KCl (30 and 16 mmol/L) after 60-120 min, and by MKP cardioplegia and KCl (10 mmol/L) after 120 min. Moderate endothelial lesions, characterised by diffuse endothelial surface changes and focal cellular loss, were induced by KCl (30 and 16 mmol/L) after 30 min, MKP cardioplegia and KCl (10 mmol) 30-60 min, LK cardioplegia, HKA cardioplegia, and MgCl2.6H2O after 120 min. Slight endothelial lesions, consisting of diffuse endothelial bulging, or absence of significant endothelial changes, were found in samples otherwise treated. Our findings showed a significant damaging effect of CPS on the human saphenous vein endothelium in-vitro. The endothelial lesions seemed related to the presence of potassium and magnesium, and to prolongation of the time of exposure to the cardioplegic solutions.(ABSTRACT TRUNCATED AT 250 WORDS)