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• Inter-atrial shunts in endurance-trained athletes: potential mechanism for EIAH during exercise.
  Darren E R Warburton
  Published on: 11 September 2006

• Published on: 11 September 2006

  Inter-atrial shunts in endurance-trained athletes: potential mechanism for EIAH during exercise.

  • Darren E R Warburton, Assistant Professor
  • Other Contributors:
    • Ben T A Esch, Shannon S D Bredin

  Dear Editor,

  We were pleased to read the innovative and compelling work by Dr. Agnoletti and colleagues [1]. The authors have eloquently (via surgical procedures) revealed the importance of right-to-left shunting (through an inter-atrial communication) on arterial oxyhemoglobin saturation during resting and exercise conditions. They have also provided convincing evidence of the detrimental effects of an inter-atrial s...

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  Dear Editor,

  We were pleased to read the innovative and compelling work by Dr. Agnoletti and colleagues [1]. The authors have eloquently (via surgical procedures) revealed the importance of right-to-left shunting (through an inter-atrial communication) on arterial oxyhemoglobin saturation during resting and exercise conditions. They have also provided convincing evidence of the detrimental effects of an inter-atrial septal defect on exercise capacity. We would also like to acknowledge that a significant proportion (50-70%) of highly trained athletes exhibit desaturation (i.e.,exercise-induced arterial hypoxemia (EIAH)) during exercise conditions [2,3]. In some instances, this desaturation occurs quite early into exercise reaching levels similar to that observed by Dr. Agnoletti et al. In our work [4] and that of others [5] approximately 10-15% of highly trained athletes (who are screened via echocardiography) are diagnosed a patent foramen ovale. It is likely that a patent foramen ovale, which is present in 10-25% of the general population, often goes undiagnosed in highly trained endurance athletes. We propose that the presence of inter-atrial septal defects may explain (in part) the marked and early desaturation observed in some highly trained athletes. It is also clear (as supported by the present work of Dr. Agnoletti et al.) that the presence of an inter-atrial communication and significant right-to-left shunting can have marked effects on exercise tolerance and capacity (in sedentary and highly trained individuals).

  We also support Dr. Agnoletti and colleagues’ statements regarding the importance of standard exercise testing for the identification of patients who can benefit from the closure of an inter-atrial communication. We respectfully would also like to extend these findings to the screening of significant inter-atrial communications. We believe that an incremental exercise test with the concurrent monitoring of arterial oxyhemoglobin saturation may be a valuable and relatively inexpensive methodology for the screening of significant inter-atrial communication in asymptomatic and symptomatic populations. This appears to be particularly salient for individuals that exhibit early (e.g., less than 50% of maximum) and severe (e.g. ≤88%) reductions in arterial oxyhemoglobin saturation during incremental exercise.

  In summary, we congratulate the authors for their detailed evaluation of the effects of inter-atrial septal defects on arterial oxyhemoglobin saturation and exercise capacity. This work provides a glimpse into a potential mechanism responsible (in part) for the early and marked EIAH observed in a subset of highly trained individuals.

  References

  1 Agnoletti G, Boudjemline Y, Ou P, et al. Right to left shunt through interatrial septal defects in patients with congenital heart disease: results of interventional closure.
  Heart 2006;92:827-31.

  2 Richards JC, McKenzie DC, Warburton DE, et al. Prevalence of exercise-induced arterial hypoxemia in healthy women.
  Med Sci Sports Exerc 2004;36:1514-21.

  3 Dempsey JA, Wagner PD. Exercise-induced arterial hypoxemia.
  J Appl Physiol 1999;87:1997-2006.

  4 Esch BTA, Scott JM, Haykowsky MJ, et al. Diastolic ventricular interactions in endurance athletes during lower body positive and negative pressure.
  Med Sci Sports Exerc 2006;38:s18.

  5 Stickland MK, Welsh RC, Haykowsky MJ, et al. Intra-pulmonary shunt and pulmonary gas exchange during exercise in humans.
  J Physiol 2004;561:321-9.

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  Conflict of Interest:
  None declared.

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