Transient right-to-left shunting through a patent foramen ovale secondary to unilateral diaphragmatic paralysis.

Abstract

Physical examination showed decreased ventilation at the right base, tachypnoea (respiratory rate 26 breaths/minute) and tachycardia (heart rate 120 beats/minute). The haemoglobin and a biochemical screen were normal. Arterial blood gas tensions when breathing room air were Pao, 4 93 kPa, Paco, 4-26 kPa, HCO3-24 mEq/l, and pH 7-48. A chest radiograph showed elevation of the right hemidiaphragm with paradoxical movement during inspiration which increased with the sniff manoeuvre. An electrocardiogram revealed sinus tachycardia with anterior hemiblock and incomplete right bundle branch block. Abdominal and thoracic ultrasonography and computed tomographic scanning excluded subphrenic and hepatic pathology. Pulmonary function tests revealed a mild restrictive ventilatory defect (vital capacity 2-761 (67% predicted), FEVI/FVC 77%, total lung capacity 4-561 (79%)). The single breath transfer factor for carbon monoxide (TLCO) was normal (109%). A right-to-left shunt was detected while the patient breathed 100% oxygen in the sitting position (Po2 7.73 kPa, Pco, 4-8 kPa). Maximal static inspiratory mouth pressure (Pimax) was reduced (-72 cm H,O) while expiratory mouth pressure (PEmax) was normal (165 cm H2O). Electromyographic studies of the right hemidiaphragm with stimulation of the phrenic nerve suggested the occurrence of a neurapraxia. A ventilationperfusion scan showed defects which were consistent with the radiographic findings. Pulmonary arteriography was normal. Transoesophageal echocardiography (figure) showed a patent foramen ovale with a right-to-left shunt from the inferior vena cava towards the foramen ovale in the interatrial septum, later confirmed by arterial angiography. Cardiac catheterisation showed normal pressures and resistance in the pulmonary artery.Another chest radiograph taken six weeks later, while the patient was being assessed for surgical correction, showed the right diaphragmatic paralysis to have resolved. Arterial blood gas tensions when breathing room air were Po, 10-4 kPa, Pco, 4-2 kPa and, after breathing 100% oxygen, Po, 75-7 kPa, Pco, 5-8 kPa (Qs/QT of 6% with an assumed arteriovenous oxygen content difference of 5 ml%).Transoesophageal echocardiography confirmed the disappearance of the right-to-left shunt. DiscussionPatent foramen ovale is a common finding among healthy people, its incidence ranging from 20% to 35% in necropsy series.3 It is often overlooked because no abnormalities are found on physical, electrocardiographic, or radiological examination; nevertheless, the importance of patent foramen ovale is that any condition causing a higher pressure in the right atrium than the left may lead to a right-to-left shunt with systemic arterial desaturation and possibly paradoxical emboli.4 This may occur during crying in the neonate,5 the Valsalva manoeuvre,6 during positive end expiratory

An uncommon cause of acute severe respiratory failure: a case report

“…Some case reports have described right to left shunting across an interatrial communication, mostly across a PFO in other circumstances but with no particularly common condition [8][9][10][11]: i.e. pulmonary embolism, unilateral diaphragmatic paralysis, pedunculated right atrial myxoma, eosinophylic myocardial disease; pericardial effusion, and the decrease of right ventricular diastolic compliance related to kyphoscoliosis.…”

Platypnoea-orthodeoxia syndrome: novel cause for a known condition

“…Miscellaneous : Laryngeal carcinoma,45 unilateral paralysis of the diaphragm,46 blunt chest wall trauma,47 new onset ileus,48 radiation-induced bronchial stenosis,49 bronchopleural fistula,50 fat embolism,51 propafenone overdose in Ebstein anomaly,52 osteoporosis and severe kyphosis,53 diabetic autonomic neuropathy,54 progressive autonomic failure55 and acute organophosphorus poisoning 56…”

Right-to-Left Atrial Shunt without Pulmonary Artery Hypertension

“…Eustachian and Thebesian valves can divert blood from the inferior vena cava and the coronary sinus through an atrial septal defect. Shunting can also occur after a right pneumonectomy [3]or right diaphragmatic paralysis [4]. Both conditions induce an angulation of the septum, bringing it closer to the inferior vena cava.…”