V Hraska

Tranexamic acid: an alternative to aprotinin as antifibrinolytic therapy in pediatric congenital heart surgery

OBJECTIVE There has been concern about the usage of aprotinin, an antifibrinolytic drug that was often used in pediatric cardiac surgery until 2006. At our center, these concerns led to the replacement of aprotinin with tranexamic acid for antifibrinolytic treatment. METHODS In this retrospective observational study, two groups of pediatric patients were studied during two different periods, receiving either aprotinin (n=70) or tranexamic acid (n=70) upon cardiac surgery. Data were collected from children with cyanotic heart defects, children who weighed less than 10 kg, and children who underwent re-operation. RESULTS There was no difference in terms of blood loss or amount of erythrocyte concentrates and fresh frozen plasma transfused. Only the intraoperative amount of platelet concentrate received by children in the tranexamic acid group was 29 ml (p=0.013) higher. There was no significant difference in the length of stay at the intensive care unit, in renal function values, or in the rate of rethoracotomy. CONCLUSIONS The results of this study suggest that tranexamic acid represents an adequate alternative to aprotinin in congenital cardiac surgery.

Prolonged Activated Clotting Time after Protamine Administration Does Not Indicate Residual Heparinization after Cardiopulmonary Bypass in Pediatric Open Heart Surgery.

BACKGROUND In open heart surgery, heparinization is commonly neutralized using an empirical heparin:protamine ratio ranging between 1:1 and 1:1.5. However, these ratios may result in protamine overdose that should be avoided for its negative side effects on the coagulation system. This study aimed to indicate the appropriate treatment for prolonged activated clotting time (ACT) after protamine administration following cardiopulmonary bypass (CPB) in pediatric open heart surgery by investigating the underlying reasons for it. METHODS Twenty-seven children (<10 kg) undergoing open heart surgery were included. Heparin was administered only before CPB (400 IU/kg) and in the pump priming volume for CPB (2,000 IU) and was neutralized by 1:1 protamine after CPB. The blood heparin concentration was measured using anti-Xa assay. ACT and blood concentrations of heparin, coagulation factors, thrombin-antithrombin complex, and prothrombin fragment 1 + 2 were assessed. A rotational thromboelastometry (ROTEM; Tem International GmbH, München, Bayern, Germany) was used to confirm the coagulation status and residual heparin after protamine administration. RESULTS Anti-Xa assay showed that there is no residual heparin in the blood after 1:1 protamine administration. Nevertheless, ACT (128.89 ± 3.09 seconds before heparin administration) remained prolonged (177.14 ± 5.43 seconds at 10 minutes after protamine, 182.00 ± 5.90 seconds at 30 minutes after protamine). The blood concentrations of coagulation factors were significantly lower than those before heparin administration (p < 0.01). The low FIBTEM MCF of ROTEM (4.43 ± 0.32 mm) at 10 minutes after protamine indicated low fibrinogen concentration. CONCLUSION Prolonged ACT after heparin neutralization by 1:1 protamine administration does not necessarily indicate residual heparin, but low blood concentrations of coagulation factors should be considered as a reason as well. Accordingly, supply of coagulation factors instead of additional protamine should be considered.

Influence of two perfusion strategies on oxygen metabolism in paediatric cardiac surgery. Evaluation of the high-flow, low-resistance technique §

OBJECTIVE Paediatric cardiac surgery is often performed under hypothermic conditions, that is, with a reduced core body temperature. Certain interventions even require the circulation to be stopped. This can only be done at a body temperature of 18 degrees C, with no risk of neurological damage and harm to the brain and other organs. Vasoconstriction is a natural reaction of the body to cold, causing the blood vessels to contract. Such a reaction would lead to a clear rise in blood pressure on cardiopulmonary bypass (CPB). Since the blood pressure is regulated in the arteriolar loop of the capillary system, there is a marked increase in blood pressure and a suppression of free water into the surrounding tissue, which, in turn, may lead to the intra-operative development of oedemas. This study aimed to investigate whether the high-flow, low-resistance (HFLR) technique offers any benefits over conventional methods. METHOD This open, prospective, randomised study was to recruit 48 children scheduled to undergo surgery for congenital heart disease. To investigate the two different perfusion strategies, we have measured intestinal perfusion as well as skin perfusion with laser Doppler spectroscopy. To identify the effects on the immune system, selected immunologic parameters of systemic inflammation were additionally measured. Laser Doppler spectroscopy is a method that uses a glass fibre probe to determine the parameters of oxygen saturation of haemoglobin and relative haemoglobin quantity in an illuminated tissue volume, as well as the perfusion parameters of relative blood flow and blood flow velocity in the sample volume of the probe. RESULTS During the study period, the change in oxygen saturation over time was comparable in both groups. At the end of surgery, the patients of the high-flow group had significantly higher saturation levels in the intestinal mucosa (p<0.05). Over the course of intensive care, the groups did not differ in terms of fluid supply, administration of packed red blood cells, platelet concentrates or fresh frozen plasma. Analysis of urinary output revealed significant group differences. It was higher in the patients of the high-flow group than the normal-flow group (p<0.03), without differences in diuretic administration. CONCLUSION Laser Doppler spectroscopy is highly suited to the detection even of the slightest changes in flow characteristics and oxygenation of the skin, musculature and intestinal mucosa during surgery with extracorporeal circulation using CPB. At the same time, the technique of HFLR perfusion was found to have benefits over conventional bypass methods.

Contemporary results of aortic valve repair for congenital disease: lessons for management and staged strategy†

OBJECTIVES Any aortic valve (AoV) operation in children (repair, Ross or mechanical replacement) is a palliation and reinterventions are frequent. AoV repair is a temporary solution primarily aimed at allowing the patient to grow to an age when more definitive solutions are available. We retrospectively analysed AoV repair effectiveness across the whole age spectrum of children, excluding neonates and AoV disease secondary to congenital heart disease. METHODS From 2003 to 2015, 193 consecutive patients were included. The mean age was 9.2 ± 6.9 years (22% <1 year); 86 (45%) had a preceding balloon valvuloplasty. The indications for the procedure were stenotic (n = 123; 64%), regurgitant (n = 63; 33%) or combined (n = 7; 4%) disease. The procedures performed were commissurotomy shaving (n = 74; 38%), leaflet replacement (n = 78; 40%), leaflet extension (n = 21; 11%) and neocommissure creation (n = 21; 11%). Post‐repair geometry was tricuspid in 137 (71%) patients. RESULTS The 10‐year survival rate was 97.1%. Freedom from reoperation and replacement at 7 years was, respectively, 57% (95% confidence interval, 47‐66) and 68% (95% confidence interval, 59‐76). In multivariate analysis, balloon dilatation before 6 months, the absence of a developed commissure, a non‐tricuspid post‐repair geometry and cross‐clamp duration were predictors for reoperation and replacement. After a mean follow‐up period of 5.1 ± 3.0 years, 145 (75%) patients had a preserved native valve, with undisturbed valve function (peak gradient <40 mmHg, regurgitation ≤mild) in 113 (58%). CONCLUSIONS Aortic valve repair in children is safe and effective in delaying the timing for more definitive solution. Surgical strategy should be individualized according to the age of the patient. Avoidance of early balloon dilatation and aiming for a tricuspid post‐repair arrangement may improve outcomes.