RESUMO
BACKGROUND: In this study we tested the hypothesis that delayed reperfusion of ischemic myocardium-too late to save myocytes-attenuates infarct expansion and improves collagen synthesis. METHODS: The hypothesis was tested in a sheep model of anteroapical infarction that has no collateral blood flow to the area at risk. After coronary ligation or arterial occlusion for 1 or 6 hours, sheep had serial hemodynamic and quantitative echocardiographic studies before and after infarction and 2, 5, 8, and 12 weeks later. Hearts were examined by light and electron microscopy at 2 and 12 weeks; hydroxyproline and ratios of type I/III collagen were measured at 12 weeks. RESULTS: After coronary occlusion, left ventricular (LV) function progressively decreased and size increased to form an anteroapical aneurysm. After 1 hour of ischemia, neither resting LV size nor function changed; the infarct contained a midmyocardial scar between epicardial and endocardial muscle. After 6 hours of ischemia, LV function was significantly better than that in nonperfused sheep. Two weeks after 6 hours of ischemia, no viable myocytes were visible by light microscopy, but electron micrographs showed rare intact nucleated myocytes with scarce cytoplasmic myofibrils. At the 12th week epicardial and endocardial myocytes reappeared in the infarct. Infarct collagen type I/III ratios were 1.2 in reperfused groups and 0.7 in nonperfused sheep. CONCLUSIONS: Delayed reperfusion causes loss and subsequent reappearance of ovine epicardial myocytes, improves collagen type I/III ratios, and attenuates LV dilatation and loss of function. One hypothesis to explain the reappearance of myocytes is that reperfusion partially reverses an incomplete apoptotic process.
Assuntos
Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/patologia , Miocárdio/patologia , Animais , Apoptose/fisiologia , Cicatriz/patologia , Colágeno/metabolismo , Endocárdio/patologia , Feminino , Masculino , Microscopia Eletrônica , OvinosAssuntos
Implante de Prótese de Valva Cardíaca/história , Próteses Valvulares Cardíacas/história , Animais , Materiais Biocompatíveis/história , Bioprótese/história , Bioprótese/tendências , Doenças das Valvas Cardíacas/cirurgia , Próteses Valvulares Cardíacas/tendências , Valvas Cardíacas/cirurgia , História do Século XX , Humanos , Desenho de Prótese/história , Desenho de Prótese/tendências , Estados UnidosRESUMO
BACKGROUND: After acute myocardial infarction, regional myocardial wall strains and stresses change and a complex cellular and biochemical response is initiated to remodel the ventricle. This study tests the hypothesis that changes in regional ventricular wall strains affect regional collagen accumulation and collagenase activity. METHODS: Fourteen sheep had acute anteroapical infarction that progressively expands into left ventricular aneurysm within 8 weeks. In 7 sheep, infarct expansion was restrained by prior placement of mesh over the area at risk. Fourteen days after infarction, and after hemodynamic and echocardiographic measurements, animals were euthanized for histology, measurements of hydroxyproline, matrix metalloproteinase-1 (MMP-1 or collagenase) and MMP-2 (gelatinase) activity, as well as collagen type I and III in infarcted, borderzone, and remote myocardium. RESULTS: Restraining infarct expansion does not change collagen content or MMP-1 or MMP-2 activity in the infarct, but significantly increases the ratio of collagen I/III. In borderzone and remote myocardium infarct, restraint significantly increases collagen content and significantly reduces MMP-1 activity. MMP-2 activity is reduced (p = 0.059) in borderzone myocardium only. Between groups, the ratio of type I/III fibrillar collagen does not change in borderzone myocardium. CONCLUSIONS: Fourteen days after acute myocardial infarction, restraining infarct expansion increases collagen accumulation in borderzone and remote myocardium, which may prevent expansion of hypocontractile, fully perfused "remodeling myocardium" adjacent to the infarct. This study demonstrates that changes in regional myocardial wall strain alter the cellular and biochemical processes involved in postinfarction ventricular remodeling.
Assuntos
Colagenases/metabolismo , Infarto do Miocárdio/cirurgia , Polipropilenos , Próteses e Implantes , Telas Cirúrgicas , Remodelação Ventricular/fisiologia , Animais , Colágeno Tipo I/metabolismo , Colágeno Tipo II/metabolismo , Gelatinases/metabolismo , Ventrículos do Coração/patologia , Ventrículos do Coração/cirurgia , Infarto do Miocárdio/patologia , Miocárdio/patologia , Ovinos , Técnicas de SuturaRESUMO
Complement activation products are major components of the inflammatory response induced by cardiac surgery and cardiopulmonary bypass which contribute to postoperative organ dysfunction, fluid accumulation, and morbidity. Activation of the complement system occurs during extracorporeal circulation, during reperfusion of ischemic tissue, and after the formation of heparin-protamine complexes. In this study we examine the efficacy of Compstatin, a recently discovered peptide inhibitor of complement, in preventing heparin/protamine-induced complement activation in baboons. The study was performed in baboons because Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans); Compstatin inhibits only the activation of primates' complement system. After testing various doses and administration regimens, Compstatin produced complete inhibition at a total dose of 21 mg/kg when given as a combination of bolus injection and infusion. Compstatin completely inhibited in vivo heparin/protamine-induced complement activation without adverse effects on heart rate or systemic arterial, central venous, and pulmonary arterial pressures. This study indicates that Compstatin is a safe and effective complement inhibitor that has the potential to prevent complement activation during and after clinical cardiac surgery. Furthermore, Compstatin can serve as the prototype for designing an orally administrated drug.
Assuntos
Ativação do Complemento/efeitos dos fármacos , Proteínas Inativadoras do Complemento/farmacologia , Peptídeos Cíclicos/farmacologia , Protaminas/antagonistas & inibidores , Animais , Biotransformação , Contagem de Eritrócitos , Índices de Eritrócitos , Hematócrito , Testes Hematológicos , Hemoglobinas/análise , Heparina , Contagem de Leucócitos , Papio , Peptídeos Cíclicos/farmacocinética , Contagem de PlaquetasRESUMO
BACKGROUND: Aprotinin reduces perioperative bleeding after open heart surgery, primarily by inhibiting fibrinolysis. In addition, the drug has both procoagulant and anticoagulant effects that involve complex reactions of coagulation proteins and cells that are incompletely understood. This study tests the hypothesis that aprotinin has an anticoagulant effect on the extrinsic coagulation pathway. METHODS: Human heparinized blood was recirculated through a membrane oxygenator with and without high concentrations of aprotinin (18.4 microM). Serial plasma samples were obtained at intervals up to 240 minutes. RESULTS: Aprotinin significantly reduced the progressive increase in prothrombin fragments (F1.2) and thrombin-antithrombin complex beginning immediately. Aprotinin also significantly reduced monocyte expression of tissue factor and Mac-1. Aprotinin did not significantly reduce factor VII or factor VIIa. CONCLUSIONS: During simulated cardiopulmonary bypass, aprotinin immediately inhibits kallikrein and thrombin formation via the intrinsic coagulation pathway. Later, aprotinin inhibits monocyte expression of tissue factor and the extrinsic coagulation pathway. The ability of aprotinin to inhibit monocyte tissue factor provides a means to reduce thrombin formation in blood aspirated from the wound during open heart surgery.
Assuntos
Aprotinina/farmacologia , Ponte Cardiopulmonar , Fator VIIa/antagonistas & inibidores , Hemostáticos/farmacologia , Monócitos/efeitos dos fármacos , Tromboplastina/metabolismo , Antitrombina III/metabolismo , Humanos , Antígeno de Macrófago 1/metabolismo , Modelos Cardiovasculares , Fragmentos de Peptídeos/metabolismo , Peptídeo Hidrolases/metabolismo , Protrombina/metabolismoRESUMO
Platelets play a major role in coagulation mechanisms and anti-GPIIb-IIIa antibodies inhibit tissue-factor induced thrombin generation in in vitro studies. Tirofiban, a nonpeptide selective glycoprotein (GP) IIb/IIIa antagonist, preserves platelet number and function during cardiopulmonary bypass (CPB) in baboons. We tested the hypothesis that platelet inhibition by tirofiban inhibits thrombin generation in vivo. Four groups of baboons (n = 7-12) were perfused for 60 min; all groups received heparin (300 units/kg). The controls received only heparin. The low dose (0.1 microg/kg/min) and high dose (0.3 microg/kg/min) infusion groups received tirofiban for 60 min before and 60 min during CPB. The bolus plus low dose infusion group received a 15 microg/kg bolus before starting CPB and a low dose infusion (0.1 mg/kg/min) only during CPB. At end of CPB, compared to control group (2.99+/-0.36 nM), prothrombin fragment F1.2 levels were lower (p<0.05) in low dose infusion group (1.65+/-0.14 nM, mean +/- SE) and high dose infusion group (1.71+/-0.19 nM), but not bolus plus infusion group (2.69+/-0.49 nM); they remained significantly lower after protamine administration. At end of CPB, thrombin-antithrombin complex levels were lower in high dose infusion group (40.0+/-11.2 ng/ml, p<0.05) compared to control group (76.2+/-7.3 ng/ml). These studies indicate that tirofiban inhibits not only platelet aggregation but also thrombin generation in vivo during CPB, and that this effect is demonstrable even in the presence of intense heparin anticoagulation. They underscore the important inhibitory effect of GPIIb-IIIa antagonists on thrombin generation.
Assuntos
Ponte Cardiopulmonar , Fibrinolíticos/farmacologia , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Trombina/antagonistas & inibidores , Tirosina/análogos & derivados , Animais , Fibrinolíticos/uso terapêutico , Complicações Intraoperatórias/prevenção & controle , Papio , Trombose/prevenção & controle , Tirofibana , Tirosina/farmacologia , Tirosina/uso terapêuticoRESUMO
OBJECTIVE: This study tested the hypothesis that nitric oxide or nitric oxide and eptifibatide (Integrilin) reversibly inhibit platelet activation and consumption during cardiopulmonary bypass and rapidly restore platelet numbers and function after bypass. METHODS: Nitric oxide, a short-acting, reversible platelet inhibitor, was studied with and without eptifibatide, a short-acting, reversible glycoprotein IIb/IIIa inhibitor, in 21 baboons that underwent 60 minutes of normothermic cardiopulmonary bypass with peripheral cannulas. A control group, a group that received 80 ppm nitric oxide, and a group that received both nitric oxide and eptifibatide were studied. Blood samples were obtained at several time points to determine platelet count, aggregation in response to adenosine diphosphate, and levels of beta-thromboglobulin, prothrombin fragment 1.2, and thrombin-antithrombin complex. Template bleeding times were measured before and at 4 intervals after cardiopulmonary bypass. RESULTS: Both nitric oxide and the combination of the 2 drugs significantly attenuated platelet consumption, improved postbypass function, and reduced plasma beta-thromboglobulin release with respect to values in control animals. Both nitric oxide and the combination restored baseline bleeding times 55 minutes after cardiopulmonary bypass ended. No significant differences between nitric oxide and the combination were found for any measurement. CONCLUSION: Nitric oxide with or without eptifibatide protects platelets during cardiopulmonary bypass and accelerates restoration of normal bleeding times after operation in a baboon model. Although nitric oxide and eptifibatide reversibly inhibit platelets by different mechanisms, in the absence of a wound no synergistic effect was demonstrated.
Assuntos
Plaquetas/efeitos dos fármacos , Ponte Cardiopulmonar , Sequestradores de Radicais Livres/farmacologia , Óxido Nítrico/farmacologia , Peptídeos/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Animais , Coagulação Sanguínea/efeitos dos fármacos , Plaquetas/fisiologia , Sinergismo Farmacológico , Quimioterapia Combinada , Eptifibatida , Período Intraoperatório , Papio , Contagem de Plaquetas/efeitos dos fármacos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Complicações Pós-Operatórias/prevenção & controle , Trombose/sangue , Trombose/prevenção & controleRESUMO
BACKGROUND: Expansion of an acute myocardial infarction predicts progressive left ventricular (LV) dilatation, functional deterioration, and early death. This study tests the hypothesis that restraining expansion of an acute infarction preserves LV geometry and resting function. METHODS AND RESULTS: In 23 sheep, snares were placed around the distal left anterior descending and second diagonal coronary arteries. In 12 sheep, infarct deformation was prevented by Marlex mesh placed over the anticipated myocardial infarct. Snared arteries were occluded 10 to 14 days later. Serial hemodynamic measurements and transdiaphragmatic quantitative echocardiograms were obtained up to 8 weeks after anteroapical infarction of 0.23 of LV mass. In sheep with mesh, circulatory hemodynamics, stroke work, and end-systolic elastance return to preinfarction values 1 week after infarction and do not change subsequently. Ventricular volumes and ejection fraction do not change after the first week postinfarction. Control animals develop large anteroapical ventricular aneurysms, increasing LV dilatation, and progressive deterioration in circulatory hemodynamics and ventricular function. At week 8, differences in LV end-diastolic pressure, cardiac output, end-diastolic and end-systolic volumes, ejection fraction, stroke work, and end-systolic elastance are significant (P<0.01) between groups. CONCLUSIONS: Preventing expansion of acute myocardial infarctions preserves LV geometry and function.
Assuntos
Ventrículos do Coração/patologia , Infarto do Miocárdio/terapia , Função Ventricular Esquerda/fisiologia , Análise de Variância , Animais , Materiais Biocompatíveis , Progressão da Doença , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Polietilenos , Polipropilenos , Ovinos , Telas CirúrgicasAssuntos
Doenças das Valvas Cardíacas/diagnóstico , Doenças das Valvas Cardíacas/terapia , Adolescente , Adulto , Antibioticoprofilaxia , Anticoagulantes/uso terapêutico , Valva Aórtica/cirurgia , Insuficiência da Valva Aórtica/diagnóstico , Insuficiência da Valva Aórtica/terapia , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/terapia , Cateterismo Cardíaco , Cateterismo , Doença Crônica , Ponte de Artéria Coronária , Ecocardiografia Doppler , Ecocardiografia Transesofagiana , Endocardite Bacteriana/prevenção & controle , Teste de Esforço , Feminino , Sopros Cardíacos/etiologia , Doenças das Valvas Cardíacas/diagnóstico por imagem , Doenças das Valvas Cardíacas/fisiopatologia , Próteses Valvulares Cardíacas , Hemodinâmica , Humanos , Valva Mitral/cirurgia , Insuficiência da Valva Mitral/diagnóstico , Insuficiência da Valva Mitral/fisiopatologia , Insuficiência da Valva Mitral/terapia , Prolapso da Valva Mitral/diagnóstico , Prolapso da Valva Mitral/terapia , Estenose da Valva Mitral/diagnóstico , Estenose da Valva Mitral/diagnóstico por imagem , Estenose da Valva Mitral/terapia , Gravidez , Complicações Cardiovasculares na Gravidez/diagnóstico , Complicações Cardiovasculares na Gravidez/terapia , Infecções Relacionadas à Prótese/diagnóstico por imagem , Infecções Relacionadas à Prótese/terapia , Angiografia Cintilográfica , Insuficiência da Valva Tricúspide/cirurgia , Disfunção Ventricular EsquerdaRESUMO
OBJECTIVE: This study tests the hypotheses that enoxaparin, a low molecular weight heparin and potent inhibitor of factor Xa, alone or in combination with standard heparin, inhibits thrombin formation and activity and modulates complement activation and neutrophil elastase release during cardiopulmonary bypass in baboons. METHODS: After preliminary studies to determine doses and possible species differences to anticoagulants and protamine, 27 anesthesized baboons had normothermic cardiopulmonary bypass with standard, unfractionated, porcine intestinal heparin, enoxaparin, or a combination of heparin and enoxaparin. Protamine in appropriate doses was used to reverse anticoagulation. Blood samples were obtained at 6 time points. Activated clotting times were monitored; template bleeding times were measured before and up to 24 hours after cardiopulmonary bypass. RESULTS: Hemodynamic measurements were not affected by the anticoagulant. Activated clotting times remained above 400 seconds throughout bypass, and no clots were observed. The anticoagulant did not alter platelet count, aggregation to adenosine diphosphate, release of beta-thromboglobulin, release of neutrophil elastase, or complement C3b/c and C4b/c. Enoxaparin alone, but not in combination, significantly reduced plasma levels of prothrombin fragment F1.2, fibrinopeptide A, and thrombin-antithrombin complexes but prolonged template bleeding times for more than 24 hours. CONCLUSION: Enoxaparin significantly reduces thrombin formation and activity during cardiopulmonary bypass but does not suppress complement activation and neutrophil elastase release and is not adequately reversed by protamine after bypass.
Assuntos
Anticoagulantes/uso terapêutico , Ponte Cardiopulmonar/efeitos adversos , Enoxaparina/uso terapêutico , Trombina/antagonistas & inibidores , Trombose/prevenção & controle , Animais , Tempo de Sangramento , Ativação do Complemento/efeitos dos fármacos , Fator Xa/metabolismo , Inibidores do Fator Xa , Heparina/uso terapêutico , Elastase de Leucócito/efeitos dos fármacos , Papio , Trombina/metabolismo , Trombose/sangue , Trombose/etiologiaRESUMO
Platelet microparticles (PMP) were isolated from outdated platelets by a combination of differential centrifugation and gel filtration, and the concentration of PMP was expressed in the equivalent of GPIIb/IIIa complex measured by captured ELISA. PMP bound to isolated neutrophils and macrophages in a dose-dependent manner, but they did not bind to lymphocytes. Incubation of PMP with neutrophils did not activate these cells as measured by up-regulation of Mac-1, release of human granulocyte elastase, and calcium mobilization. Incubation of PMP with macrophages did not enhance IL-8 production and the oxygen burst but slightly and significantly increased production of MCP-1. After 10 min incubation of PMP with macrophages, an increase of GPIIb/IIIa antigen was observed suggesting that PMP may be endocytosed by macrophages. In conclusion, PMP bind to leukocytes, but, in contrast to activated platelets, do not play a significant role in leukocyte activation.
Assuntos
Plaquetas/citologia , Preservação de Sangue , Leucócitos/citologia , Biomarcadores , Plaquetas/metabolismo , Separação Celular , Centrifugação , Quimiocina CCL2/análise , Cromatografia em Gel , Endocitose , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Humanos , Interleucina-8/análise , Leucócitos/metabolismo , Ativação de Macrófagos , Macrófagos/citologia , Macrófagos/fisiologia , Neutrófilos/citologia , Neutrófilos/metabolismo , Selectina-P/análise , Fatores de TempoRESUMO
This article reviews the roles of the contact and complement systems and of neutrophils and monocytes in the inflammatory response to cardiopulmonary bypass and open heart operation. These blood proteins and cells, together with other blood elements, produce the vasoactive and cytotoxic substances and microemboli that cause the morbidity associated with cardiopulmonary bypass and open heart operation.
Assuntos
Ponte Cardiopulmonar , Ponte de Artéria Coronária , Gestão de Riscos , Síndrome de Resposta Inflamatória Sistêmica/imunologia , Ativação do Complemento/imunologia , Humanos , Mediadores da Inflamação/sangue , Monócitos/imunologia , Ativação de Neutrófilo/imunologia , Resistência Vascular/fisiologiaRESUMO
OBJECTIVE: Transmyocardial laser revascularization is an investigational technique for revascularizing ischemic myocardium in patients with inoperable coronary arterial disease. This study tests the hypothesis that laser revascularization prevents left ventricular functional deterioration and aneurysm formation after acute anteroapical myocardial infarction. METHODS: An ultrasonic ascending aortic flow probe and snares around the distal left anterior descending and second diagonal coronary arteries were placed in 26 Dorsett hybrid sheep. Ten to 14 days later, snared arteries were occluded to produce an anteroapical infarction of 23% of left ventricular mass. Before infarction 14 animals had 34 +/- 4 transmyocardial perforations in the area of the anticipated infarction made with a carbon dioxide laser. Twelve animals served as controls. Hemodynamic measurements and transdiaphragmatic quantitative echocardiograms were obtained before, immediately after, and 2, 5, and 8 weeks after infarction. Eighteen sheep completed the protocol. RESULTS: All animals had large anteroapical left ventricular aneurysms with massive ventricular enlargement. Immediately after infarction the anterior wall became thinner and dyskinetic in all sheep. At 8 weeks aneurysmal size and shape were indistinguishable between groups. Two days after infarction, laser holes were filled with fibrin. At 5 and 8 weeks the infarct consisted of dense collagen, fibroblasts, scattered calcifications, myocyte fragments, neutrophils, macrophages, and no laser holes. There were no significant differences at any time between groups for cardiac pressures or output, ventricular volumes, ejection fraction, stroke work, and the stroke work-left ventricular end-diastolic pressure index. CONCLUSION: Transmyocardial laser perforations do not revascularize acute myocardial infarction in sheep.
Assuntos
Aneurisma Cardíaco/patologia , Terapia a Laser , Infarto do Miocárdio/patologia , Revascularização Miocárdica , Disfunção Ventricular Esquerda/patologia , Animais , Ecocardiografia , Fibrina/metabolismo , Ventrículos do Coração/patologia , Ventrículos do Coração/cirurgia , Hemodinâmica/fisiologia , Miocárdio/patologia , Ovinos , Falha de TratamentoRESUMO
Cardiopulmonary bypass causes hemorrhagic complications, and initiates a chemical and cellular inflammatory response. Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, complement, and contact systems. Despite the fact that cardiopulmonary bypass is carried out in the presence of high doses of heparin, there is significant activation of both platelets and neutrophils. Thrombin is protected on cell and fibrin surfaces from antithrombin, even in the presence of high doses of heparin (approximately 5 U/ml). We therefore studied the effect of a small (Mr = 497), highly effective (Ki = 41 pM), reversible tripeptide inhibitor of thrombin, DUP 714 (1 microM), in a well characterized model of simulated extracorporeal circulation. In the absence of DUP 714, platelet counts decreased by 75% 5 min after the start of extracorporeal bypass and increased to 48% at 120 min of recirculation. DUP 714 significantly preserved platelet counts, decreased plasma levels of platelet beta-thromboglobulin levels, but did not prevent a decrease in sensitivity of platelets to adenosine diphosphate. Kallikrein-C1-inhibitor and C1-C1-inhibitor complexes increased progressively from 0.32 U/ml to 0.67 U/ml and from 4.45 U/ml to 7.25 U/ml, respectively, during 120 min of recirculation without DUP 714. Addition of DUP 714 significantly inhibited kallikrein-C1-inhibitor complex formation but did not affect C1-C1-inhibitor complexes. In the absence of DUP 714, human neutrophil elastase levels rose from a baseline of 0.01 +/- 0.00 microg/ml to 1.18 +/- 0.21 microg/ml during 120 min of recirculation. Human neutrophil elastase release at 120 min was significantly inhibited in the presence of DUP 714 to 37% of the value with heparin alone. These results indicated that addition of this novel thrombin (and kallikrein) inhibitor to heparin preserved platelet counts, decreased platelet secretion, and provided the additional benefit of partially blocking neutrophil activation during simulated extracorporeal circulation.
Assuntos
Ponte Cardiopulmonar , Circulação Extracorpórea , Calicreínas/metabolismo , Trombina/metabolismo , Humanos , Ativação de Neutrófilo , Ativação PlaquetáriaRESUMO
BACKGROUND: Cardiopulmonary bypass reduces platelet number and function, increases postoperative bleeding time, and is the major, unsolved cause of nonsurgical bleeding after open heart operations. Temporary inhibition of platelet function during cardiopulmonary bypass (platelet anesthesia) protects platelets and reduces postoperative bleeding time and bleeding. METHODS: Integrilin, a short-acting, reversible platelet glycoprotein IIb/IIIa inhibitor was studied in 28 baboons that had 60 minutes of normothermic cardiopulmonary bypass using peripheral cannulas. A control group, two groups that received different doses of Integrilin, and a group that received a combination of Integrilin and low-dose Iloprost were studied. Blood samples for platelet count, aggregation to adenosine diphosphate, beta-thromboglobulin, prothrombin fragment F1.2, thrombin-antithrombin complex, and fibrinopeptide A were obtained at seven time points. Template bleeding times were measured before and at five intervals after cardiopulmonary bypass. RESULTS: Both doses of Integrilin and the combination of Integrilin and Iloprost significantly protected platelet number, inhibited the response to adenosine diphosphate, and reduced postoperative bleeding times, but they did not reduce beta-thromboglobulin release except in the high-dose Integrilin group. Thrombin formation and activity were qualitatively, but not significantly, reduced in all treatment groups. Bleeding times were not significantly different from baseline at the time protamine was given in the combination group and 60 minutes after protamine administration in all treatment groups. CONCLUSIONS: Integrilin alone or in combination with Iloprost significantly reduces platelet activation during cardiopulmonary bypass and produces normal or near-normal bleeding times at the time protamine is given.
Assuntos
Tempo de Sangramento , Ponte Cardiopulmonar , Peptídeos/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , Animais , Eptifibatida , Fibrinopeptídeo A/análise , Iloprosta/administração & dosagem , Papio , Fragmentos de Peptídeos/análise , Peptídeos/administração & dosagem , Inibidores da Agregação Plaquetária/administração & dosagem , Protaminas/administração & dosagem , Protrombina/análise , beta-Tromboglobulina/análiseRESUMO
A captured enzyme-linked immunosorbent assay (ELISA) using the disintegrin, kistrin, is described and used to measure platelet microparticles (PMP) generated during open heart surgery. This ELISA detects 75 ng/ml of glycoprotein IIb/IIIa (GPIIa/IIIa) in solution and is more sensitive and less variable than flow cytometry and radioimmunoassay. By ELISA, mean values of GPIIb/IIIa in PMP are 14.2 +/- 7.9 microg/ml for outdated platelets and 0.28 +/- 0.1 microg/ml in fresh blood from healthy donors. Normal washed platelets (10(8)) contain 8.8 microg of GPIIb/IIIa. In 12 cardiac surgical patients, PMP measured by ELISA significantly increased (p = 0.039) to 0.58 +/- 0.3 microg/ml at the end of cardiopulmonary bypass, but the increase measured by flow cytometry (1207 to 1447 events in PMP gate) was not significant. Neither heparin nor protamine alter PMP. After cardiopulmonary bypass, PMP concentrations return to baseline values before protamine is given. Concentrations of PMP in pericardial blood are greater than in simultaneous perfusate. This ELISA is more sensitive and accurate than alternate methods for measuring PMP and shows the PMP production and rapid clearance during open cardiac surgery.