Abstract
Aims: To quantitatively evaluate the basic pathophysiological process involved in the creation of Eisenmenger syndrome in pediatric pulmonary arterial hypertension (PAH) patients by either atrial septostomy (AS) or Potts shunt (PS) as well as to predict the effects of AS or PS in future PAH patients.Methods: The multi-scale lumped parameter CircAdapt model of the cardiovascular system was used to investigate the effects of AS and PS on cardiovascular hemodynamics and mechanics, as well as on oxygen saturation in moderate to severe PAH. The reference simulation, with cardiac output set to 2.1 l/min and mean systemic pressure to 61 mmHg, was used to create a compensated moderate PAH simulation with mPAP 50 mmHg. Thereupon we created a range of decompensated PAH simulations in which mPAP was stepwise increased from 50 to 80 mmHg. Then we simulated for each level of mPAP the acute effects of either PS or AS with connection diameters ranging between 0–16 mm.Results: For any mPAP level, the effect on shunt flow size is much larger for the PS than for AS. Whereas right ventricular pump work in PS is mainly dependent on mPAP, in AS it depends on both mPAP and the size of the defect. The effects on total cardiac pump work were similar for PS and AS. As expected, PS resulted in a drastic decrease of lower body oxygen saturation, whereas in AS both the upper and lower body oxygen saturation decreased, though not as drastically as in PS.Conclusion: Our simulations support the opinion that a PS can transfer suprasystemic PAH to an Eisenmenger physiology associated with a right-to-left shunt at the arterial level. Contrary to the current opinion that PS in PAH will decompress and unload the right ventricle, we show that while a PS does lead to a decrease in mPAP toward mean systemic arterial pressure, it does not unload the right ventricle because it mainly diverts flow from the pulmonary arterial system toward the lower body systemic arteries.
Highlights
Idiopathic pulmonary arterial hypertension is a rare, progressive, and devastating disease if left untreated
The latter panels clearly show that whereas a Potts shunt (PS) results in lowering of mean pulmonary arterial pressures (mPAPs) toward mean systemic arterial pressure, an atrial septal defect (ASD) barely influences right heart pressures
We show that for any mPAP level, the effect on shunt flow size is much larger for the PS than for the created ASD
Summary
Idiopathic pulmonary arterial hypertension (iPAH) is a rare, progressive, and devastating disease if left untreated. Though AS improves symptoms and quality of life in adults and children with severe iPAH, the sizing of the defect is critical since too much right-to-left shunt at the atrial level could be immediately life threatening because of insufficient pulmonary blood flow as well as severe desaturation in the brain and in the coronary circulation, and too less shunting may require repeated procedures because of spontaneous closure of the defect (Micheletti et al, 2006) Another approach to convert iPAH patients to Eisenmenger physiology arose a decade ago and calls for the creation of an anastomosis between the descending aorta and the left pulmonary artery (Blanc et al, 2004). Transcatheter creation of PS by stenting a patent ductus arteriosus (PDA) in pediatric iPAH patients had a comparable clinical success rate outcome (Boudjemline et al, 2013; Esch et al, 2013; Latus et al, 2014; Boudjemline et al, 2017)
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