Arterial desaturation dependent on posture.

A 60-year-old woman developed subacute bacterial endocarditis following a minor operation. She presented the unusual picture of breathlessness with cyanosis related to posture, confirmed by laboratory measurement. She had an atrial septal defect with right-to-left shunt, and had sustained multiple pulmonary infarcts, resulting iin the obliteration of a large section of her pulmonary vascular bed. The puzzling absence of pulmonary hypertension was explained by tricuspid incompetence, although there was no clinical evidence of this, and on two occasions the right atrial pressure tracing was normal. The use of a balloon catheter to predict the results of operation is described. At operation the severely damaged tricuspid valve was replaced, and the septal defect was closed. There was an immediate improvement in the arterial oxygen tension after operation. She subsequently survived an episode of ventricular fibrillation, left hospital 11 months after her original admission and is now leading a normal life. The occurrence of central cyanosis in a patient with an intracardiac shunt is normally due to an increase in right heart pressures, and is clearly understood. The transient development of this sign associated with an alteration in-posture is less common , and the case we are describing involves a combination of circumstances producing this clinical sign. CASE HISTORY In December 1966, two weeks after an operation for removal of a fibro-adenoma of the breast, a 60-year-old woman developed general malaise with rigors and vomiting. In February 1967 she was noted to be febrile and to have an apical systolic murmur. There was no history of rheumatic fever. Blood and urine cultures grew Proteus vulgaris but treatment with a number of antibiotics, alone and in combination, produced only a slight improvement. During relapses her temperature rose to 104' F. (40' C.). In July she complained of breathlessness when sitting up and subEequently this was observed to be accompanied by cyanosis. The breathlessness and cyanosis disappeared on lying down. In July and August she had two episodes of pleuritic chest pain. During this period she became breathless and cyanosed when lying down, these signs being more marked when she sat up. These clinical observations were confirmed by the following values of arterial oxygen saturation which also showed that desaturation was unaffected by breathing oxygen. The results were as follows: Supine, breathing air Supine, after breathing 100% oxygen for 5 min. Sitting, breathing air Arterial Oxygen Saturation (%) 68 68 59 These results indicate …