Endothelial function: Relationship between coronary grafts and brachial artery in patients of coronary artery bypass surgery

PROTO VÍCTOR; JOO TURONI, CLAUDIO; MARAÑON RODRIGO; SALINAS JUAN; MUNTANER JUAN; PERAL DE BRUNO MARIA

Buenos Aires

Congreso; XVI Congreso Mundial de Cardiología; 2008

World Heart Federation

In coronary artery bypass grafting surgery (CABGS), internal mammary artery (IMA) and saphenous vein (SV) are used as bypass conduits. In previous works, we demonstrated in isolated IMA from patients of CABGS an impaired endothelial function [Clinical and Experimental Hypertension 29:327–344; 2007]. Endothelial function may be evaluated by non-invasive method estimating the flow-mediated dilatation (FMD) in brachial artery. The objective of the present work was to compare the endothelial function in rings of IMA and SV with FMD of brachial arterial in patients from CABGS. Material and methods: From 26 patients of CABGS, paired rings (4 mm) of discarded segments of IMA and SV were obtained. In both vessels, endothelial-dependent relaxation was evaluated by the effect of acetylcholine (Ach 10–9–10–4 M) in precontracted noradrenaline (NA)-vessels. Endothelial function was considered present or absent when ring relaxed (E+) or not (E-) to Ach (-40% of NA precontraction). Complementary studies with immunohistochemistry examination (monoclonal CD34 antibodies) were performed in order to test the presence of endotelium. In addition, in this group, 13 randomized patients were selected in order to assay FMD in brachial artery by impedancimetric method. FMD was expressed as difference of pulse wave pressure trough-peak before and after 5 min of total arterial occlusion. Endothelium was considered present when FMD increased _10% of basal pulse wave pressure. FMD was also compared with 13 healthy subjects. Results: Ach response detected E- in IMA from 24 patients and E- in SV from 21 patients. That means values of Ach effect were -23.4_12.4mg (corresponding to 1.05% of NA-precontraction) and _89.8_28.6mg (6.1% of NAprecontraction) in IMA and SV respectively. In both IMA and SV the immunohistochemistry studies showed similar results than Ach response. No significant correlation in the presence of E_/E- between IMA and SV was found (Chi square: 1.9; p_NS). Endothelial dysfunction estimated by FMD was present in 11 patients. FMD values were significantly lower in patients than healthy subjects (-6.4_5.0; n_13 vs _20.1_5.8%; n_13 respectively; p<0.02). In addition the proportion of patients with impaired endothelial response by FMD was similar to that observed “in vitro” in IMA and SV rings (p_0.21 and p_0.37 respectively, the difference between two percentages: NS). Discussion: Although IMA is the main vessel used in CABGS, is controversial its endothelial integrity. In this work, it was compared, for the first time, the endothelial function in isolated IMA and SV rings with FMD in brachial artery, demonstrating that not only IMA and SV showed an impaired endothelial function but also this dysfunction may be present in other peripheral vessels.