Successful Percutaneous Closure of a Patent Foramen Ovale Causing Hypoxia in the Setting of an Elevated Hemidiaphragm Due to Gui

Patent foramen ovale (PFO) is a frequent, but relatively insignificant, clinical finding. An estimated 20–30% of the population may have the anomaly. The majority of PFOs are not associated with clinical or physiologic events. Recently, PFOs have been implicated as a source of paradoxical emboli in cryptogenic strokes. Rarely, PFOs are associated with right-to-left shunts and associated hypoxia. The right-to-left shunt may be attributed to pressure differences, but can occur with no increases in right-sided pressures. This occurs when there is streaming of blood due to anatomical changes. There have only been a few reported cases of shunting through a PFO secondary to an elevated (paralyzed) hemidiaphragm. We report a case of hypoxia due to right-to-left shunting through a PFO in the setting of an elevated right hemidiaphragm and the utility of percutaneous closure. Although this has been reported before,^1–3 our case is unique in that it was associated with Guillian-Barre syndrome. The closure of the PFO resulted in a significant improvement in the patient’s hypoxia and is only the second case associated with an elevated hemidiaphragm to have been documented.¹Case Presentation An 84-year-old Caucasian female was transferred to our institution with refractory hypoxia after developing Guillian-Barre syndrome 1 month earlier. The diagnostic work-up at the outside hospital included a computed tomography scan of her chest, which was negative for any pathology except an elevated right hemi-diaphragm and segmental atelectasis. A sniff test subsequently confirmed paralysis of the right hemidiaphragm. A transthoracic echocardiogram utilizing agitated saline contrast, however, showed evidence of a large PFO with right-to-left shunting. Upon the patient’s arrival to our institution, a portable chest X-ray showed an elevated right hemidiaphragm (Figure 1). Arterial blood gases obtained on room air showed a PaO2 of 48 mmHg, with an oxygen saturation of 87%. She subsequently underwent right heart catheterization which showed normal pressures (mean RA: 5, RV: 19/2, PA: 22/5 and PCWP: 5). Cardiac magnetic resonance imaging showed a small, distorted right atrium with extrinsic compression. It also confirmed the PFO with significant right-to-left shunting and a large atrial-septal aneurysm. She complained of increasing dyspnea while sitting up and improvement of her symptoms while supine, but remained hypoxic in either position. With continued hypoxemia and elevated hemidiaphragm, the patient was taken to the cardiac catheterization laboratory with plans to close the defect with an Amplatzer® ASD Occluder (AGA Medical Corp., Golden Valley, Minnesota). A TEE performed in the catheterization laboratory showed a PFO measuring 0.6 cm, with a large atrial-septal aneurysm protruding into the left atrium. Right-to-left shunting was demonstrated by color flow Doppler (Figure 2). The patient was intubated prior to the procedure. She immediately had decompression of the right atrium and marked improvement of the shunting (Figure 3). The stretched diameter during the sizing procedure proved the defect to be much larger, measuring 12 mm by angiographic assessment. A 14 mm Amplatzer ASD Occluder was successfully deployed, with resolution of the shunt (Figure 4). The PaO2 improved to 67 mmHg, and her oxygen saturation increased to 95% while breathing room air. The patient was discharged to a rehabilitation facility 3 days later on room air with a saturation of 95%. Her right hemidiaphragm remained elevated. Discussion Hypoxia due to shunting through a PFO is very uncommon.⁴ Causes include acute right ventricular dysfunction due right ventricular infarction, pulmonary hypertension of any cause and the platypnea-orthodeoxia syndrome.⁵ Acute pulmonary embolism is also an important cause that must be excluded.6 In a search of the literature there appears to only be three other reported cases of hypoxia due to an elevated hemidiaphragm.^1–3 Guillian-Barre syndrome has never been implicated as a cause. In addition, our patient appeared to have a component of the platypnea-orthodeoxia syndrome. Patients suffering from this syndrome have been shown to have normal right heart pressures and resolution of symptoms with closure of their PFO.⁷ Several other factors make this case unique. Normal rightsided pressures associated with an elevated hemidiaphragm have only been described in two other instances.^1,3 Transesophageal echocardiography (TEE) was performed on our patient before endotracheal intubation, showing distortion of the right atrium and bowing of the atrial septum with significant shunting. Upon intubation and application of positive pressure ventilation, the patient experienced a significant decrease in the degree of right-to-left shunting, with a clear change in the anatomy of her right atrium and septum. We postulated that the positive pressure was enough to “push down” the right hemidiaphragm and change the geometry of the right atrium, thereby decreasing the shunt. The PFO was closed successfully with an Amplatzer ASD Occluder. The Amplatzer device was chosen because of the size of the PFO and the significant distortion of the atrial septum. Although the patient’s hypoxia did not resolve completely (she still had a elevated right hemidiaphragm and atelectesis), the closure of the PFO allowed the patient to possibly avoid long-term ventilation, and to subsequently be discharged to a rehabilitation facility.

References 1. Ghamande S, Ramsey R, Rhodes J, Stoller J. Right hemidiaphragmatic elevation with a right-to-left shunt through a patent foramen ovale. Chest 2001;120:2094–2096. 2. Murray KD, Kalanges LK, Weiland JE, et al. Platypnea-orthodeoxia: An unusual indication for surgical closure of a patent foramen ovale. J Cardiac Surgery 1991;6:62–67. 3. Cordero PJ, Morales P, Mora V, et al. Transient right-to-left shunting through a patent foramen ovale secondary to unilateral diaphragmatic paralysis. Thorax 1994;49:933–934. 4. Godart F, Rey C, Prat A, et al. Atrial right-to-left shunting causing severe hypoxaemia despite normal right-sided pressures. Eur Heart J 2000;21:483–489. 5. Al Khouzaie T, Busser J. A rare cause of dyspnea and arterial hypoxemia. Chest 1997;112:1681–1682. 6. Konstantinides S, Geibel A, Kasper W, et al. Patent foramen ovale is an important predictor of adverse outcomes in patients with major pulmonary embolism. Circulation 1998;97:1946–1951. 7. Rao P, Palacios I, Bach R, et al. Platypnea-orthodeoxia: Management by transcatheter buttoned device implantation. Catheter Cardiovasc Interv 2001;54:77–82.