Platelet function in stored heparinised autologous blood is not superior to in patient platelet function during routine cardiopulmonary bypass.

BACKGROUND: In cardiac surgery, cardiopulmonary bypass (CPB) and unfractionated heparin have negative effects on blood platelet function. In acute normovolemic haemodilution autologous unfractionated heparinised blood is stored ex-vivo and retransfused at the end of the procedure to reduce (allogeneic) transfusion requirements. In this observational study we assessed whether platelet function is better preserved in ex vivo stored autologous blood compared to platelet function in the patient during CPB. METHODOLOGY/PRINCIPAL FINDING: We measured platelet aggregation responses pre-CPB, 5 min after the start of CPB, at the end of CPB, and after unfractionated heparin reversal, using multiple electrode aggregometry (Multiplate®) with adenosine diphosphate (ADP), thrombin receptor activating peptide (TRAP) and ristocetin activated test cells. We compared blood samples taken from the patient with samples taken from 100 ml ex-vivo stored blood, which we took to mimick blood storage during normovolemic haemodilution. Platelet function declined both in ex-vivo stored blood as well as in blood taken from the patient. At the end of CPB there were no differences in platelet aggregation responses between samples from the ex vivo stored blood and the patient. CONCLUSION/SIGNIFICANCE: Ex vivo preservation of autologous blood in unfractionated heparin does not seem to be profitable to preserve platelet function.

Bivalirudin is inferior to heparin in preservation of intraoperative autologous blood.

INTRODUCTION: Bivalirudin is used as an alternative to heparin in cardiac surgery, and may be superior to heparin with regard to platelet function. Bivalirudin however, is prone to cleavage by thrombin resulting in coagulation in areas of stasis. MATERIAL AND METHODS: We compared the preservation of platelet function and the quality of anticoagulation in autologous blood of 26 cardiac surgical patients collected intraoperatively and anticoagulated ex vivo with either bivalirudin or heparin, with supplementation of bivalirudin over time and prevention of stasis. RESULTS: We found in both preservatives a reduction in ADP-induced platelet aggregation response over a period of 105 minutes (median, IQR: 73-141) as measured by Multiplate®. Supplementation of additional bivalirudin (23 ± 1.1 µg/ml/hr) and prevention of stasis was not able to prevent thrombin generation. We found a 5-fold increase in levels of prothrombin fragment 1+2 in bivalirudin preserved autologous blood as compared to heparin preserved blood (F(1+2) levels median 8.9 nM [quartile percentiles 4.2-12.4] vs 1.3 nM [0.6-2.1], P=0.001 Mann-Whitney, n=10). CONCLUSIONS: Our study suggests that preservation of platelet function in autologous blood anticoagulated with bivalirudin is not a suitable alternative to heparin.

Effects of preemptive enoximone on left ventricular diastolic function after valve replacement for aortic stenosis.

OBJECTIVE: Left ventricular (LV) hypertrophy is associated with increased diastolic chamber stiffness early after aortic valve replacement for valve stenosis. Enoximone, a phosphodiesterase III inhibitor, has been shown to improve myocardial contractility and relaxation when administered as a single dose after cardiac surgery. The present study investigated, by analysis of transmitral flow velocity patterns and end-diastolic pressure-area relations, whether enoximone administered before aortic valve surgery has an effect on LV diastolic properties. DESIGN: Prospective, randomized study. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: Thirty-four patients undergoing aortic valve replacement for aortic stenosis. INTERVENTIONS: Patients in the enoximone group (n = 17) received a bolus dose of 0.35 mg/kg (0.15 mg/kg before aortic cross-clamping and 0.2 mg/kg added to the cardioplegic solution). Individual pressure-area relations (pulmonary capillary wedge pressure v left ventricular end-diastolic area) were obtained by using volume loading by leg elevation before and after surgery with closed chest. MEASUREMENTS AND MAIN RESULTS: The pressure-area relation on the pressure-area plot was shifted to the left after surgery, indicating decreased LV diastolic distensibility in the enoximone and control groups and providing evidence of decreased LV diastolic function. Indices of LV diastolic chamber stiffness, LV operating stiffness (K(LV)) derived from the deceleration time of early ventricular filling, and the constant of chamber stiffness (beta) derived from pressure-area relations were not different after enoximone treatment. Systolic LV function was unaltered after cardiac surgery in both groups. Analysis of changes in transmitral flow patterns identified an increased atrial filling fraction in enoximone-treated patients, suggesting increased atrial systolic function. The unaltered systolic pulmonary venous flow velocity compared with the decrease in the control group after volume loading further supports preservation of left atrial reservoir function with enoximone in the absence of evidence for decreased LV stiffness. CONCLUSION: Preemptive enoximone did not change LV diastolic function based on diastolic filling patterns or LV stiffness indices (K(LV) and beta) derived from Doppler early filling deceleration time and pressure-area relations. Doppler data suggested improvement of left atrial systolic function and preservation of left atrial reservoir function with enoximone.