thromboxane-b2 and Heart-Valve-Diseases

Nitric oxide is the most potent vasodilator among inflammation-mediated vasoactive substances. Tepid cardiopulmonary bypass has been known to maintain low vascular resistance and nitric oxide may also be involved. There has been no previous clinical study elucidating a role of nitric oxide in a temperature dependent regulation of systemic vascular resistance in cardiopulmonary bypass.. Thirty-one patients who underwent valvular surgery were randomly divided into two comparable groups; consisting of the hypothermic cardiopulmonary bypass (28 degrees C:14 patients) and the tepid cardiopulmonary bypass group (34 degrees C:17 patients). The serum levels of nitric oxide (NO(2)(-)+NO(3)(-)), prostaglandin E(2), bradykinin, 6-keto PGF1alpha, thromboxane B(2), endothelin-1, systemic vascular resistance index were measured before, 0, 12 and 24 h after cardiopulmonary bypass.. The pattern of change in systemic vascular resistance index and nitric oxide during and after cardiopulmonary bypass were significantly different between the two groups (P=0.0008, P=0.02). The tepid group showed significantly lower levels of systemic vascular resistance index after cardiopulmonary bypass than the hypothermic group (0 h: 2278+/-735 vs. 4387+/-1289, 12 h: 1827+/-817 vs. 2817+/-1146 and 24 h: 1690+/-548 vs. 2761+/-641 dyne s cm(-5) m(2), P=0.0001, P=0.03, P=0. 0006). The nitric oxide levels were significantly higher at 0, 12 and 24 h after cardiopulmonary bypass in the tepid group than those in the hypothermic group (84.7+/-33.3 vs. 46.3+/-18.1, 69.8+/-31.1 vs. 40.1+/-17.5 and 80.1+/-38.5 vs. 39.1+/-15.6 micromol/l, P=0.008, P=0.03, P=0.01). The prostaglandin E(2) levels in the tepid group was significantly higher just after cardiopulmonary bypass than that in the hypothermic group (37.3+/-20.0 vs. 15.8+/-8.6 pg/ml, P=0.02). The bradykinin level in the hypothermic group was significantly higher just after cardiopulmonary bypass than that in the tepid group (2.40+/-0.32 vs. 1.85+/-0.21 log(10) (pg/ml), P=0.005). Only nitric oxide showed a significant negative correlation with the systemic vascular resistance index both during and after cardiopulmonary bypass (r=-0.60, P<0.0001) as compared with prostaglandin E(2) and bradykinin.. These findings demonstrated that serum nitric oxide levels in tepid cardiopulmonary bypass were significantly higher than those in hypothermic cardiopulmonary bypass. Nitric oxide correlated with systemic vascular resistance. Thus, nitric oxide may play a pivotal role in a temperature dependent regulation of systemic vascular resistance in cardiopulmonary bypass.

Topics: Biomarkers; Blood Gas Analysis; Bradykinin; Cardiopulmonary Bypass; Endothelin-1; Heart Valve Diseases; Heart Valve Prosthesis Implantation; Humans; Hypothermia, Induced; Intraoperative Period; Middle Aged; Monitoring, Intraoperative; Nitric Oxide; Prostaglandins; Thromboxane B2; Vascular Resistance; Vasoconstriction

Patients who underwent operations in which cardiopulmonary bypass was used had elevations of plasma fibrinopeptide A which did not return to normal during bypass despite conventional heparin anticoagulation, suggesting inadequate heparin dosage and continued thrombin activity during the operation. Patients who underwent aortocoronary artery grafting had high plasma thromboxane B2 levels and a rapid fall in platelet count at the onset of extracorporeal circulation. Thromboxane elevations were less marked in patients who underwent valve replacement. Platelet aggregation and coronary artery constriction secondary to thromboxane production may contribute to the morbidity of cardiopulmonary bypass.

Topics: Adult; Cardiopulmonary Bypass; Coronary Artery Bypass; Fibrinogen; Fibrinopeptide A; Heart Valve Diseases; Hematocrit; Humans; Platelet Count; Radioimmunoassay; Thromboxane B2; Thromboxanes