title: Recurrent orthodeoxia and patent foramen ovale.
abstract: BACKGROUND
  Patent foramen ovale (PFO) occurs in 25% of healthy adults. It can lead to paradoxical embolization, migraine and respiratory failure (RF). The authors present a case of RF and orthodeoxia due to a right-to-left shunt via a PFO without previous elevation of right atrial pressure. Closure of the PFO effectively resolved the RF.
  
  
  METHODS
  A 52-year-old man, with IgA-k multiple myeloma diagnosed one year before, was admitted for severe hypoxemic RF, with orthodeoxia and poor response to oxygen supplementation, after placement of a central venous catheter (CVC) in the right subclavian vein. The patient reported paresthesia and nonspecific visual changes after manipulation of the CVC. The RF suggested a shunt between the pulmonary and systemic circulations. There was no clinical or radiological evidence of an intrapulmonary shunt. Contrast echocardiography showed a right-to-left shunt and transesophageal echocardiography revealed a PFO. Cardiac catheterization, after spontaneous resolution of the RF, showed no shunt. A week later, severe RF recurred. Complete resolution of respiratory dysfunction and neurological symptoms was seen after PFO closure.
  
  
  CONCLUSIONS
  RF due to an intracardiac shunt without increased right-sided pressure is hemodynamically difficult to interpret. A few reports (in adults) relate this entity to anatomical anomalies, which can lead to a shunt by directing blood flow preferentially to the PFO. Examples include right diaphragmatic paresis and ectasia of the ascending aorta, which were observed in this patient. The role of the CVC, which was placed immediately before the RF, is uncertain. Complete therapeutic success after closure of the PFO supports the diagnosis.
  
  
  CONCLUSIONS
  Correct evaluation of RF (by investigating orthodeoxia and response to oxygen therapy) enables the suspicion of a shunt, which can be confirmed through simple, safe and cost-effective exams. Intracardiac shunt without increased right-sided pressure should be considered because it can be successfully treatment.
authors.affiliation: Centro Hospitalar do Porto, Hospital de Santo António, Serviço de Medicina, Porto, Portugal. mluisamag@yahoo.com
authors.forename: Luísa
authors.initials: L
authors.lastname: Magalhães
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Pinto
authors.forename: Júlio R
authors.initials: JR
authors.lastname: Oliveira
authors.forename: Filomena
authors.initials: F
authors.lastname: Oliveira
authors.forename: Ernestina
authors.initials: E
authors.lastname: Reis
mesh_terms: D054092:Foramen Ovale, Patent / Q000150:complications*; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012131:Respiratory Insufficiency / Q000209:etiology*