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Fresh heparinised blood: Is its use justified?
Asia Pacific
Heart J 1998;7(1)
Royal
Children’s
Hospital
Paediatric
Cardiac
Symposium SUPPLEMENT
Fresh Heparinised Blood: Is Its Use Justified? Robert Eyres Department of Anaesthesia, Royal Children’s Hospital, Melbourne, Australia Fresh heparinised blood was initially used for cardiopulmonary bypass in infants less than 10 kg to reduce the risk of citrate toxicity. Other advantages include the increased number and activity of platelets, increased levels of 2,3-DPG, less initial free haemoglobin, and an increased activity of soluble coagulation factors. Another but largely unrecognised factor is the absence of glucose in units of heparinised
blood. In titrated stored blood, the amount of added glucose has been found to be up to 55 mmol/L, providing a pump prime with a measured osmolality of up to 350 milliosmol/kg. Hyperglycaemia per se is capable of exacerbating brain damage induced by cardiopulmonary bypass, but a rapid large osmolar load of this dimension at the initiation of bypass creates an environment for further major brain damage.
Update On Pulmonary
AV Fistulae
Brodie Knight Department of Cardiology, Adelaide Women’s and Children’s Hospital, Adelaide, Australia It is well known that pulmonary arteriovenous fistulae develop in up to 25% of patients who have undergone a classical Glenn operation (right SVC-RPA anastomosis) but generally take many years to become obvious. Most reports have described discrete macroscopic fistulae, always lateralised to the side of the shunt.
right to left shunt after total cavopulmonary anastomosis, keeping in mind the previous cohort of patients who underwent classical Glenn operation, the natural extension of the hypothesis is that telangiectases and possibly eventually discrete pulmonary arteriovenous fistulae may develop in patients with usual situs after bidirectional cavopulmonary shunt. Until now, other investigators have not found evidence of pulmonary telangiectia in this group of patients; reports of increasing cyanosis have been described in which systemic venovenous communications have been found. Using probably the most sensitive indicator for the presence of early right to left intrapulmonary shunt, namely contrast echocardiography, all patients who have had bidirectional cavopulmonary shunt investigated by contrast echocardiography showed evidence of intrapulmonary right to left shunt. Those who have gone on to have completion of Fontan operation and who have had further peripheral venous contrast echocardiography have shown an improvement, indicating resolution of right to left intrapulmonary shunting in some.
Patients with abnormalities of thoracoabdominal situs have been reported to develop a telangiectatic form of right to left intrapulmonary shunt, usually bilaterally, even in the absence of any cardiac surgical palliation. Following total cavopulmonary anastomosis in those with left atrial isomerism and IVC interruption, the early to mid-term development of bilateral diffuse pulmonary telangiectasia is relatively common (approximately 1520%) and has frequently led to death secondary to progressive hypoxia. Unilateral diffuse pulmonary telangiectasia has been described in the occasional patient after unusual types of modified Fontan operation in which only 1 lung receives hepatic venous return; in these cases the opposite lung develops the telangiectases. In addition, the reversal of intrapulmonary right to left shunting following liver transplantation in patients with end stage liver disease is well described. On the basis of these data, the hypothesis that a labile liver-derived substance maintains the integrity of the pulmonary microcirculation was developed and subsequently supported by several reports of reversal of the shunt in patients with left isomerism and total cavopulmonary anastomosis following further surgery to divert hepatic venous blood to both lungs (“hepatopulmonary connection”). While patients with left isomerism seem to be predisposed to the development of pulmonary telangiectasia resulting in early and severe pulmonary
These data suggest that, like patients with classical Glenn operations, the longer the postoperative follow-up, the more likely it is that a significant number will develop clinically important right to left intrapulmonary shunting and perhaps also discrete macroscopic pulmonary arteriovenous fistulae. These may in turn be complicated by severe CNS infection and paradoxical embolism. Completion of Fontan operation may result in improvement or disappearance of intrapulmonary right to left shunting if performed early enough. Discrete macroscopic fistulae would be unlikely to be improved by this operation.
56
Heart J 1998;7(1)
Royal
Children’s
Hospital
Paediatric
Cardiac
Symposium SUPPLEMENT
Fresh Heparinised Blood: Is Its Use Justified? Robert Eyres Department of Anaesthesia, Royal Children’s Hospital, Melbourne, Australia Fresh heparinised blood was initially used for cardiopulmonary bypass in infants less than 10 kg to reduce the risk of citrate toxicity. Other advantages include the increased number and activity of platelets, increased levels of 2,3-DPG, less initial free haemoglobin, and an increased activity of soluble coagulation factors. Another but largely unrecognised factor is the absence of glucose in units of heparinised
blood. In titrated stored blood, the amount of added glucose has been found to be up to 55 mmol/L, providing a pump prime with a measured osmolality of up to 350 milliosmol/kg. Hyperglycaemia per se is capable of exacerbating brain damage induced by cardiopulmonary bypass, but a rapid large osmolar load of this dimension at the initiation of bypass creates an environment for further major brain damage.
Update On Pulmonary
AV Fistulae
Brodie Knight Department of Cardiology, Adelaide Women’s and Children’s Hospital, Adelaide, Australia It is well known that pulmonary arteriovenous fistulae develop in up to 25% of patients who have undergone a classical Glenn operation (right SVC-RPA anastomosis) but generally take many years to become obvious. Most reports have described discrete macroscopic fistulae, always lateralised to the side of the shunt.
right to left shunt after total cavopulmonary anastomosis, keeping in mind the previous cohort of patients who underwent classical Glenn operation, the natural extension of the hypothesis is that telangiectases and possibly eventually discrete pulmonary arteriovenous fistulae may develop in patients with usual situs after bidirectional cavopulmonary shunt. Until now, other investigators have not found evidence of pulmonary telangiectia in this group of patients; reports of increasing cyanosis have been described in which systemic venovenous communications have been found. Using probably the most sensitive indicator for the presence of early right to left intrapulmonary shunt, namely contrast echocardiography, all patients who have had bidirectional cavopulmonary shunt investigated by contrast echocardiography showed evidence of intrapulmonary right to left shunt. Those who have gone on to have completion of Fontan operation and who have had further peripheral venous contrast echocardiography have shown an improvement, indicating resolution of right to left intrapulmonary shunting in some.
Patients with abnormalities of thoracoabdominal situs have been reported to develop a telangiectatic form of right to left intrapulmonary shunt, usually bilaterally, even in the absence of any cardiac surgical palliation. Following total cavopulmonary anastomosis in those with left atrial isomerism and IVC interruption, the early to mid-term development of bilateral diffuse pulmonary telangiectasia is relatively common (approximately 1520%) and has frequently led to death secondary to progressive hypoxia. Unilateral diffuse pulmonary telangiectasia has been described in the occasional patient after unusual types of modified Fontan operation in which only 1 lung receives hepatic venous return; in these cases the opposite lung develops the telangiectases. In addition, the reversal of intrapulmonary right to left shunting following liver transplantation in patients with end stage liver disease is well described. On the basis of these data, the hypothesis that a labile liver-derived substance maintains the integrity of the pulmonary microcirculation was developed and subsequently supported by several reports of reversal of the shunt in patients with left isomerism and total cavopulmonary anastomosis following further surgery to divert hepatic venous blood to both lungs (“hepatopulmonary connection”). While patients with left isomerism seem to be predisposed to the development of pulmonary telangiectasia resulting in early and severe pulmonary
These data suggest that, like patients with classical Glenn operations, the longer the postoperative follow-up, the more likely it is that a significant number will develop clinically important right to left intrapulmonary shunting and perhaps also discrete macroscopic pulmonary arteriovenous fistulae. These may in turn be complicated by severe CNS infection and paradoxical embolism. Completion of Fontan operation may result in improvement or disappearance of intrapulmonary right to left shunting if performed early enough. Discrete macroscopic fistulae would be unlikely to be improved by this operation.
56