Assessment of platelet function in patients on antiplatelet therapy undergoing cardiac surgery: a review.

Increasing numbers of patients are undergoing cardiac surgery on dual antiplatelet therapy following previous percutaneous coronary intervention. The dilemma of stopping antiplatelet therapy prior to surgery with risk of stent thrombosis, versus continuation and risk of post-operative bleeding has received much debate. Currently, an accurate and standardised method of predicting antiplatelet drug efficacy has not yet been determined and significant inter-individual variance has been shown. This review focuses on the most widely used laboratory and point of care assays currently available to measure platelet function and recent published data evaluating these methods. Further studies may enable predictive values to be defined, to guide the practicing clinician in balancing the risk of thrombosis versus haemorrhage.

Effect of 4-aryl-2-methyl-5-nitro-1,4-dihydropyridine-3-carboxylates on the guinea pig papillary muscle and isolated human vena saphena magna that is used for coronary artery bypass grafting.

BACKGROUND: The goal of this study was to estimate: (i) the action of 5-nitro-substituted 1,4-dihydropyridines as well as Bay K 8644 (CAS [71145-03-4]) and CGP 28392 (CAS [89289-93-0]) on cardiac action potential duration (APD) and isometric contraction in the isolated guinea pig papillary muscles; (ii) whether the effects of 2-propoxyethyl 4-(2-difluoromethoxyphe-nyl)-2-methyl-5-nitro-1,4-dihydropyridine-3-carboxylate on the lengthening of cardiac APD were related to certain potassium channels (e.g., I(K1), K(ATP) and I(K)); and (iii) the modulation of the contraction-relaxation effects on isolated human vena saphena magna samples using three 5-nitro-substituted 1,4-dihydropyridine derivatives, displaying the positive inotropic and AP duration effects. METHODS: The experiments were conducted on isolated human vena saphena magna samples and papillary muscles from adult guinea pigs. Isometric contractions and APs were recorded using a force transducer and microelectrode technique, respectively. RESULTS: 2-Propoxyethyl 4-(2-difluoromethoxyphenyl)-2-methyl-5-nitro-1,4-dihydropyridine-3-carboxylate significantly increased APD and isometric contractions in a concentration-dependent manner. Its effects were suppressed by dl-sotalol. Other derivatives tested, such as Bay K 8644 and CGP 28392, showed either negligible effects or increased the contraction force but did not influence the APD. Compounds possessing positive inotropic properties at a concentration of 10(-7) to 10(-4) M significantly relaxed the isolated vessel samples pre-contracted with phenylephrine (10(-4) M). The weakest response was shown by 2-propoxyethyl 4-(2-difluoromethoxyphenyl)-2-methyl-5-nitro-1,4-dihydropyridine-3-carboxylate. CONCLUSION: These results show that 5-nitro-substituted 1,4-dihydropyridine derivatives with positive inotropic action significantly relaxed isolated vein samples that were pre-contracted with phenylephrine in a dose-dependent manner. 2-Propoxyethyl 4-(2-difluoromethoxyphenyl)-2-methyl-5-nitro-1,4-dihydropyridine-3-carboxylate prolongs the cardiac APD, which could be determined by the rapid component I(Kr) of the delayed potassium current I(K) blocker.

[Prediction and evaluation of surgical treatment results of severe ischemic heart disease]. / Uzleistos isemines sirdies ligos chirurginio gydymo rezultatu prognozavimas bei vertinimas.

OBJECTIVES: To estimate myocardial perfusion in patients with severe coronary artery disease performing before and early after single-photon emission computed tomography coronary artery bypass grafting; to predict results of complete myocardial revascularisation by preoperative perfusion data. MATERIAL AND METHODS: Ten patients with stable coronary artery disease and resting left ventricular wall motion abnormalities (mean ejection fraction 31.8+/-6.4%, mean wall motion index 2.09+/-0.25) underwent (99m)Tc-MIBI single-photon emission computed tomography at rest and after nitrate administration before coronary artery bypass grafting and stress-rest single-photon emission computed tomography early (3 and 6 months) after surgery. We estimated myocardial perfusion, postoperative recovery and calculated scintigraphic indices. RESULTS: The mean number of distal anastomoses was 3.0+/-0.7 and all of the patients had complete myocardial revascularisation. Out of 84 revascularized segments with different degree of myocardial perfusion disorders, 49 (58.3%) segments improved after 3 months and 53 (63.1%) improved after 6 months postoperatively. Amount of segments with fixed perfusion defects increased from 60 preoperatively to 72 after 3 months and 67 after 6 months. Postoperative myocardial perfusion recovery was incomplete following 3 months, but after 6 months it nearly reached ultimate level. Postoperative index of myocardial perfusion recovery was found better than predicted preoperatively. CONCLUSIONS: Estimation of myocardial perfusion changes with single-photon emission computed tomography during early postoperative period, particularly after 6 months, confirms excellent and final results of complete surgical myocardial revascularization. Preoperative single-photon emission computed tomography after nitrate administration provides more information in prediction of postoperative results of complete myocardial revascularization. Estimation of function of fixed perfusion defects can help to predict correct results and to identify hibernating myocardium.

[Estimation of myocardial perfusion changes after surgical revasculization with single-photon emission computed tomography]. / Miokardo perfuzijos pokyciu ivertinimas po chirurgines revaskulizacijos sirdies radionuklidines kompiuterines tomografijos metodu.

OBJECTIVE: to estimate myocardial perfusion performing single-photon emission computed tomography before and in early period after coronary artery bypass grafting; to predict results of complete myocardial revascularisation by preoperative perfusion data. MATERIAL AND METHODS: Ten patients with stable coronary artery disease and resting left ventricular wall motion abnormalities (mean ejection fraction 37.7+/-6.5%, mean wall motion index 1.89+/-0.32) underwent 99mTc-MIBI myocardial perfusion single-photon emission computed tomography before and in early period (3 and 6 months) after coronary artery bypass grafting. We estimated myocardial perfusion, postoperative recovery and calculated scintigraphic indices. RESULTS: The mean number of distal anastomoses was 3.5+/-0.9 and all of patients had complete myocardial revascularization. Postoperatively 39 (66.1%) after 3 months and 45 (76.3%) after 6 months of 59 revasculared segments with different degree of myocardial perfusion disorders improved. Postoperative (after 6 months) index of myocardial perfusion recovery was found more than 2 times better than predicted preoperatively, because there was no estimation of hibernating myocardium preoperatively. CONCLUSIONS: Estimation of myocardial perfusion changes with single-photon emission computed tomography in early postoperative period, especially after 6 months, confirms the excellent and final results of complete surgical myocardial revascularization. Present protocol of myocardial perfusion investigation gives incomplete information in prediction of postoperative results of complete myocardial revascularization. Myocardial perfusion study performed after nitrate administration is the method of choice to predict correct results.