POSTOPERATIVE MANAGEMENT OF LOW CARDIAC OUTPUT STATE (CONGENITAL HEART SURGERY)
Z. Slavik*
Department of Paediatrics, Royal Brompton Hospital, London, UK. *
Incidence of low cardiac output state (LOS) has remained relatively stable (around 25% of cases) following paediatric cardiac surgical treatment despite a change in the spectrum of treated congenital heart defects and age over the years (1, 2). Definition of LOS involves markers of poor tissue perfusion using clinical and laboratory criteria (3). LOS contributes to early post-operative mortality, morbidity and longterm cognitive dysfunction. Traditional treatment of LOS included artificial ventilation with administration of catecholamines and vasodilators.

Recent preventive strategies targeted reduction in postoperative inflammatory response by preoperative administration of steroids (4) and the use of modified ultrafiltration at the end of cardiopulmonary bypass run (5). Early postoperative use of inhaled nitric oxide reduces the incidence of LOS due to right ventricular failure in infants and children following cardiac surgery (6).

Preoperative administration of milrinone (representative of phospodiesterase-3 inhibitors) was shown to reduce incidence of postoperative LOS in neonates, infants and children undergoing corrective cardiac surgery (3. 7). Its hemodynamic benefit relates to its ionotropic, lusitropic and vasodilating effect independent of alfa-and beta-receptors (8). Our recently published data support the direct beneficial myocardial effect of milrinone even in paediatric patients with established LOS in early postoperative period (9). Temperature control including mild hypothermia (to 34-33 deg C) has been used successfully in the treatment of LOS not only in association with atrial tachydysrhythmias (10).

Early institution of mechanical circulatory support (ECMO or VAD) in patients with LOS may be considered a preventive strategy or a successful treatment option in carefully selected patients (11).

Pediatric patients with LOS are likely to benefit in future from the advent of a new calcium sensitizer, Levosimendan, with inotropic and peripheral vasodilating effect into clinical practice (12). Tighter postoperative control of glycaemia with or without administration of insulin may improve outlook of children with LOS even further (13).
References :
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  2. Parr GVS. Blackstone EH, Kirklin JW. Cardiac performance and mortality early after intracardiac surgery in infants and young children. Circulation 1975;51:867-874.
  3. Hoffman TM, Wernovsky G, Atz AM et al. Efficacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease. Circulation 2003;107:996-1002.
  4. Bronicky AR, Backer CL, Baden HP, et al. Dexamethasone reduces the inflammatory response to cardiopulmonary bypass in children. Ann thorac surg 200;69:1490-1495.
  5. Yndgaard S, Andersen LW, Andersen C, et al. The effect of modified ultrafiltration on the amount of circulating endotoxins in children undergoing cardiopulmonary bypass. J Cardiothorac Vasc Anesth 2000;14:399-341.
  6. Russell IA, Zwass MS, Fineman JR, et al. The effects of inhaled nitric oxide on postoperative pulmonary hypertension in infants and children undergoing surgical repair of congenital heart disease. Anesth Analg 1998;87:46-51.
  7. Chang AC, Atz AM, Wernovsky G, et al. Milrinone; systemic and pulmonary hemodynamic effects in neonates after cardiac surgery. Crit Care Med 1995;23:1907-1914.
  8. Polla B, Capelli V, Canepari M, et al. Direct depressant effect of phosphodiesterase inhibitors on ATPase activity of cardiac myofibrils. Can Physiol Pharmacol 1995;73:661-664.
  9. Duggal B, Pratap U, Slavik Z, et al. Milrinone and low cardiac output following cardiac surgery in infants: Is there a direct myocardial effect? Pediatr Cardiol 2005;26:1-5.
  10. Dalrymple-Hay MJ, Deakin CD, Knight H, et al. Induced hypothermia as salvage treatment for refractory cardiac failure following paediatric cardiac surgery. Eur J Cardiothorac Surg 1999;15:515-518.
  11. Langley SM, Sheppard SV, Tsang VT, et al. When is extracorporeal life support worth-while following repair of congenital heart disease in children? Eur J Cardiothorac Surg 1998;13:520-525.
  12. Braun JP, Schneider M, Kastrup M, et al. Treatment of acute heart failure in an infant after cardiac surgery using levosimendan. Eur J Cardiothorac Surg 2004;26:228-230.
  13. Halverson-Steele B, Zizkova E, Slavik Z, et al. Glycemia as a marker of outcome in pediatric cardiac intensive care. The Fifth International Symposium on Pediatric Cardiac Intensive Care, Miami, USA, 2005:A-517.
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