Reverse Potts Shunt for Pulmonary Arterial Hypertension in Children
Potts shunt was a surgical anastomosis between left pulmonary artery and descending aorta to improve pulmonary blood flow in cyanotic congenital heart disease with decreased pulmonary blood flow. It is a systemic to pulmonary shunt. The report was published one year after the Blalock-Taussig shunt which was also used for a similar purpose . Later Potts shunt like other central aortopulmonary shunts, were discontinued because of higher risk of excessive pulmonary blood flow. A modified Blalock-Taussig shunt is still in use.
Reverse Potts shunt is a pulmonary to systemic shunt for relieving pulmonary arterial hypertension. It is called reverse Potts shunt because the pressure in the pulmonary circulation is higher than that in systemic circulation . The idea of creating a Potts shunt in children with severe pulmonary hypertension was based on the information that children with Eisenmenger syndrome had a better life expectancy than severe pulmonary arterial hypertension [3,4]. An unrestrictive shunt between pulmonary artery and descending aorta reduces the afterload on right ventricle from suprasystemic to systemic levels. This equalization of right and left ventricular systolic pressures produces a physiology similar to that of Eisenmenger syndrome, typically that of patent ductus arteriosus with Eisenmenger syndrome and right to left shunt. Compared to an atrial septostomy which produces global hypoxemia, a Potts shunt will direct highest oxygenated blood to the child’s brain.
Data from palliative Potts shunt for the treatment of drug refractory pulmonary arterial hypertension in the first 24 children was published in 2015 . Nineteen of these patients had conventional surgical Potts shunt while the remaining 5 had transcatheter stenting of remnant patent ductus arteriosus. One case had a unidirectional valved Potts shunt for a child with infrasystemic pulmonary arterial hypertension on intravenous epoprostenol who had repeated central line infections. Severe post operative complications occurred in 6 patients in the surgical group, including 3 early deaths related to low cardiac output. For the survivors, over a 2.1 year median follow up, there was significant clinical improvement in majority of children. It was associated significant reduction in medications for pulmonary arterial hypertension. Weaning of epoprostenol was obtained in all patients who received triple combination prior to Potts anastomosis.
Retrospective data on 110 children with pulmonary arterial hypertension who underwent a shunt procedure from 13 centres in Europe and United States is now available from the International Potts shunt registry . There were 17 post procedure in hospital deaths. 18 of the 93 children successfully discharged home died subsequently or underwent lung transplantation during a mean follow up of 3.1 years (range 25 days to 17 years). 59% of children were weaned completely from prostacyclin infusion after the procedure. Preprocedural risk factors for inhospital mortality were admission to intensive care unit, mechanical ventilation and extracorporeal membrane oxygenation. This would mean that the procedure should be considered before they are severely ill and requiring aggressive intensive care. It was mentioned that five year survival was comparable to children undergoing lung transplantation for pulmonary hypertension.