Decline in Arterial pO2 after Exercise can Help Stratify Patients with Large Atrial Septal Defect and Pulmonary Hypertension

  • Srinivas Lakshmivenkateshiah, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • Anil Singhi, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • Edwin Francis, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • Balu Vaidyanathan, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • Mahesh Kappanayil, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • R Sundaram, Amrita Institute of Medical Sciences, Kochi, Kerala, India
  • Raman Kumar, Amrita Institute of Medical Sciences, Kochi, Kerala, India

    • Objectives: To examine the utility of decline in arterial partial pressure of oxygen (paO2) after exercise as a marker of pulmonary vascular obstructive disease (PVOD) in patients with ASD with PAH.

    Methods: A symptom limited treadmill exercise was performed in three groups of patients: Healthy volunteers (n = 6), large ASD with no PAH (n = 5) and 15 patients with ASD and PAH. Patients with resting saturation < 90% were excluded. Arterial blood gas samples were obtained before and immediately following peak exercise. Patients with ASD and PAH underwent cardiac catheterization and detailed hemodynamic data sets were obtained on room air, oxygen and, a mixture of oxygen and nitric oxide (30-40 ppm).

    Results: None of the controls (healthy or ASD and no PAH) had a drop in paO2 except one healthy volunteer (9mmHg decline). In the study group, all the patients who had >10mmHg drop in paO2 after exercise (n=9) had a basal PVRi of >7WU.m2. Five of 6 patients who had <10mmHg drop in paO2 after exercise had a basal PVRi of < 7WU.m2 (p=0.001). A decline in paO2 of >10mmHg predicted a basal PVRi of >7WU.m2 with a specificity of 100% and a sensitivity of 90%.

    Parameter ≥10mmHg drop in PaO2 after exercise (n=9) < 10mmHg drop in PaO2 after exercise(n=6) p Value
    Age (yr) 28.67± 7.29 40.17± 4.3 0.005
    Basal PaO2 (mmHg) 76.62 ±13.46 80 ± 12.1 NS
    Mean PA pressure (mmHg) at Basal 57.77 ± 13.68 40 ± 10.8 0.019
    Mean PA pressure (mmHg) On oxygen inhalation 57.22 ± 13.99 34.4 ± 11.26 0.008
    Mean PA pressure (mmHg) 30-40ppm Nitric Oxide 53.13± 10.80 32.2± 9.06 0.003
    Number of patients with a PVRi ≥7 wood units.m2 at Basal, On oxygen inhalation, on 30-40ppm Nitric Oxide 9,7,5 1,0,0 0.002,.02,.02
    Number of patients with a PVRi < 7 wood units.m2 at Basal, On oxygen inhalation, on 30-40ppm Nitric Oxide 0, 2, 3 5, 5, 5 0.002,.02,.02