Author + information
- Yasunaga Shiraishi, MD,
- Daihiko Hakuno, MD, PhD⁎ (, )
- Kikuo Isoda, MD, PhD,
- Kouji Miyazaki, MD, PhD and
- Takeshi Adachi, MD, PhD
- ↵⁎National Defense Medical College, Division of Cardiology, Department of First Internal Medicine, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan
A 75-year-old man had occasionally been referred to our hospital with sudden dyspnea due to unknown causes. He had a history of hypertension and polycystic kidneys and had undergone transcatheter pulmonary vein isolation for paroxysmal atrial fibrillation 2 years previously. Physical examination revealed normal heart sounds without murmurs and was otherwise unremarkable. Electrocardiography, chest radiography, and blood tests were also normal. Oxygen saturation was 98% on room air in the supine position, but once he sat up, oxygen saturation suddenly dropped, causing dyspnea. He was then admitted for further investigation. Continuous oxygen saturation monitoring showed that it decreased negligibly during standing or walking but decreased strikingly to 72% just after sitting or squatting. Chest computed tomography, spirometry, and lung perfusion scintigraphy showed no findings of lung disease or pulmonary embolism. Transthoracic echocardiography showed dilation of the sinus of Valsalva and ascending aorta without abnormal shunting, pulmonary hypertension, or ventricular diastolic dysfunction.
During the previous transcatheter pulmonary vein isolation procedure, some interatrial communication had been suspected. Therefore, we performed transesophageal echocardiography and found a patent foramen ovale (PFO). Tilt-table transesophageal echocardiography with a contrast agent showed negligible right-to-left (RL) shunting in the supine position (Fig. 1A, Online Video 1) and by a passive postural change, whereas sitting or abdominal compression caused prominent RL shunting with hypoxemia and dyspnea (Fig. 1B, Online Video 2). Right-heart catheterization revealed that the ratio of pulmonary blood flow to systemic blood flow was 1.0 and showed no evidence of abnormal intracardiac pressures, thereby negating the possibility of Eisenmenger syndrome. However, simultaneous transcatheter measurement of interatrial pressures via the PFO proved that the mean pressure gradient was only 1 mm Hg in the supine position (Fig. 1C), whereas it dramatically increased to 7 mm Hg after sitting, especially during inspiration (Fig. 1D). Chest computed tomography with a contrast agent revealed that the sinus of Valsalva and ascending aorta were dilated to 4.2 and 4.0 cm in diameter, respectively, and oriented in a horizontal direction, compressing the interatrial septum into the right atrium to lead venous return from the inferior vena cava to the PFO (Figs. 2A and 2B). These findings were confirmed by transesophageal echocardiography as well (Fig. 2C). We therefore diagnosed our patient with platypnea-orthodeoxia syndrome due to the PFO and aortic dilation. After its surgical closure, the patient remained well with no further symptoms.
Platypnea-orthodeoxia syndrome is a clinically striking syndrome of postural hypoxemia with breathlessness (1). Two factors must coexist for this syndrome to develop: 1) the anatomical factor may be an interatrial communication via an atrial septal defect, PFO, or fenestrated atrial septal aneurysm; and 2) the functional factor may be cardiac, such as constrictive pericarditis; pulmonary, such as pulmonary emphysema, recurrent pulmonary embolism, arteriovenous malformation, or previous pneumonectomy; abdominal, such as liver cirrhosis; or vascular, such as an aortic aneurysm or elongation, all of which might cause a deformity of the atrial septum (2,3). Several causes of RL shunting have been hypothesized, such as redirection of shunt flow or a stretch of an interatrial hole that occurs with a postural change and a decrease in right ventricular compliance accentuating the interatrial gradient with respiration and the Valsalva maneuver (4). In this case, the RL shunt was not provoked by a passive postural change on a tilt table but by sitting, especially during inspiration, and abdominal compression. Accordingly, we speculated that the compression of the right atrium by aortic dilation, the positional relationship between the inferior vena cava and the PFO, and an increase in venous return to the right atrium accounted for RL shunting via the PFO.
Platypnea-orthodeoxia syndrome is recognized as a relatively uncommon condition and might be overlooked. However, patients with interatrial communication are not rare. Therefore, this syndrome should be kept in mind in patients presenting with dyspnea with postural hypoxemia.
For supplementary videos and their legends, please see the online version of this article.
- American College of Cardiology Foundation