Platypnea of vascular origin

Specialty: Cardiovascular.

• orthostatic dyspnea
• platypnea-orthodeoxia of circulatory origin

Why it occurs

• Platypnea-orthodeoxia syndrome secondary to patent foramen ovale with right-left postural shunt
• Pulmonary arteriovenous fistulas
• Hepatopulmonary syndrome
• Myxoma of the right or left atrium that obstructs valve flow posturally
• Aneurysm of the ascending aorta with distortion of the interatrial septum when upright

Initial workup

Pulse oximetry and comparative arterial blood gases in the supine and standing position to objectively document orthodeoxia; Transthoracic and transesophageal echocardiogram with injection of microbubbles (agitated saline solution) to evaluate the passage of bubbles to the left atrium, defining the number of beats in which the passage occurs to differentiate an intracardiac shunt (patent foramen ovale or atrial septal defect, passage in <3 beats) from an intrapulmonary shunt (fistulas, passage in >4 beats); Computed tomography angiography of the chest or lung perfusion scan.

Standard management

• Supplementary oxygen therapy — as temporary support while the correction of the anatomical defect is carried out; flow adjusted to maintain saturation >90% in standing position
• Enoxaparin — low molecular weight anticoagulant indicated if associated with deep vein thrombosis to prevent shunts with paradoxical thromboembolism; 1 mg/kg subcutaneous every 12 hours
• Spironolactone — aldosterone antagonist, useful if the underlying etiology is hepatopulmonary syndrome with cirrhosis and associated ascites; 100 mg once a day orally
• Propranolol (non-selective beta-blocker, useful as supportive treatment in hepatopulmonary syndrome; 20 to 40 mg twice daily orally).