Fluid challenge and balloon occlusion testing in patients with atrial septal defects

D’Alto M, Constantine A, Chessa M, Santoro G, Gaio G, Giordano M, Romeo E, Argiento P, Wacker J, D’Aiello AF, Sarubbi B, Russo MG, Naeije R, Golino P, Dimopoulos K.

Heart. 2022 May 12;108(11):848-854. doi: 10.1136/heartjnl-2021-319676.

PMID: 34413090


Take Home Points

  • Left ventricular filling pressure determination pre closure of atrial septal defects (ASD) is a recommendation by ESC trans-catheter closure guideline
  • Fluid challenge (0.9% saline, 7 ml/kg over 10 minutes) and ASD balloon occlusion testing showed smaller increase in pulmonary blood flow and decrease in shunt fraction in patients with higher (≥ 2 Wood Units) vs lower pulmonary vascular resistance
  • Small rises in PVR ≥2 WU may carry significant implications with regard to cardiovascular hemodynamics in patients with ASD and fluid challenge may aid complementary information to LV diastolic disease, however larger studies and data standardization regarding cut off values is needed

Commentary from Dr. Shailendra Upadhyay (Connecticut, USA), section editor of ACHD Journal Watch:


ASD closure may pose challenges in elevated pulmonary vascular resistance (PVR) with persistence of pulmonary vascular disease and in elevated left ventricular filling with resulting pulmonary edema after. European Society of Cardiology (ESC) guidelines advise measurement of left atrial (LA) or pulmonary arterial wedge pressure (PAWP) before and after balloon occlusion, however, guidance regarding the interpretation of these data is lacking. Fluid challenge has been utilized in PH centers to unmask LV disease. The study aimed to investigate the hemodynamic effects of fluid challenge or balloon occlusion, impact of mildly elevated PVR in patients selected for percutaneous ASD closure.



Prospective multicenter study at three centers in Italy (January 2018 – December 2020). Inclusion criteria included cases referred for percutaneous secundum ASD closure, Qp:Qs>1.5. Hemodynamic data collections included: right atrial pressure (RAP), systolic, diastolic and mean pulmonary arterial pressure (mPAP), LA/PAWP, Qp:Qs and Fick cardiac output. PVR and SVR were reported in Wood Units (WU).

Fluid Challenge: volume loading with infusion of 0.9% sodium chloride of 7 mL/kg over 10 min. Balloon occlusion involved temporarily closing the ASD with a sizing balloon. Measurements were taken at 4 points as noted in figure 1. Of the patients 88% underwent percutaneous ASD closure, 3 (6%) fenestrated ASD closure and 3 (6%) were untreated. Echocardiogram assessment of PH and diastolic function was performed at follow-up.


Diagram Description automatically generated



N=50, mean age 46 years, 72% females. Individuals with Individuals with a PVR ≥2 WU at baseline hemodynamic assessment (higher PVR group) were older [mean 58 vs 42 years]


Fluid Challenge: After fluid challenge, statistically changes in hemodynamics were noted including a small increase in PAWP, the difference between PAWP and RAP, mean PAP increased by an average of 3 mmHg despite an open ASD. QP and Qs both increased but Qp had a more substantial elevation [2L/min], thereby increasing the Qp:Qs modestly [0.1] i.e. more left to right shunting and small reductions in PVR and SVR.


Patients with higher baseline PVR, findings included smaller Qp increase, greater mPAP increase and significant difference in change in PVR. Qp:Qs remained > 1.5 in low PVR group and in nearly all (90%) with elevated PVR, Qp:Qs dropped below 1.5.



Parameters with fluid loading and PVR ≤2 WU PVR ≥2 WU Comment
Qp ↑↑
Qs ↑↑
Qp:Qs > 1.5 Yes No Dropped below 1.5
mPAP ↑↑
PAWP/RAP Not statistically significant
PVR Not statistically significant
SVR ↓↓

Balloon Occlusion test with and without concurrent fluid challenge testing:




Combined fluid challenge and balloon occlusion had similar effects on RAP, PAWP, PVR and mPAP in the higher and lower PVR groups, whereas there was a more pronounced reduction in SVR in the higher PVR group associated with a greater increase in PVR/SVR (p=0.0003 and p=0.026, respectively).

At a mean follow-up of 27 months, all patients were alive, none developed signs of PH or diastolic dysfunction on follow-up echocardiogram.



  • ASDs with PVR <5 are deemed suitable for repair per ESC guidelines
  • However, a significant difference in hemodynamics was detected between patients with a PVR ≥2 and ≤2 WU, at baseline and after fluid challenge and balloon occlusion.
  • Patients with a higher baseline PVR were older and more often symptomatic, with significantly lower baseline Qp and shunt fraction, but with similar PAWP and had smaller Qp:Qs after fluid bolus.
  • ASDs may mask LV diastolic dysfunction by acting as a relief valve
  • While balloon occlusion has a role in this setting, authors suggest that fluid challenge has a complementary role in unmasking latent diastolic dysfunction, which may not be obvious after balloon occlusion alone.
  • Fluid challenge can also test the ability of the pulmonary vascular bed to increase Qp, and may provide information on the resistance and compliance of the pulmonary circulation.
  • This study suggests that even modest rises in PVR ≥2 WU may carry significant implications with regard to cardiovascular hemodynamics in patients with ASD.
  • Fluid challenge may provide complementary information to balloon occlusion in this setting, but further studies are needed to standardise this approach and establish robust cut-offs to define LV disease, which current guidelines suggest should influence management.