Puzzling Dyspnea

Abstract

INTRODUCTION: We present a clinical puzzle of a middle aged man with worsening dyspnea. CASE PRESENTATION: A 65-year-old Chinese man presented to the respiratory unit for progressive dyspnea of 6 monthsaTM duration. He first consulted Cardiology 2 months ago for the same complaint. He did not have accompanying chest pain, orthopnea, paroxysmal nocturnal dyspnea or leg edema. He did not complain of cough, wheeze or weight loss. However he noticed a marked decline in the functional status as he could no longer negotiate a flight of stairs in contrast to 4 storeys previously. He was a former smoker of 10 pack-years; other than being a chronic Hepatitis B carrier, he denied misuse of drugs, did not keep birds as pets and was never exposed to industrial chemicals or mining. He had worked as a hawker and newspaper delivery man, and had since retired due to dyspnea. Before a myocardial perfusion scan was performed, he presented to the emergency department with worsening dyspnea. CBC: hemoglobin 16.7 g/dl (12.9-17), normal white, differential and platelet counts; urea-electrolytes, liver function test and cardiac enzymes were normal. N-terminal pro-brain natriuretic peptide (NT-pro BNP) was elevated 4450 pg/ml (0-194). EKG showed a resting heart rate of 92/ min with right axis deviation. CXR suggested right hilar prominence; arterial blood gas on ambient air revealed marked hypoxia PaO2 43 mmHg with normal PaCO2. Contrasted CT thorax showed bilateral mediastinal adenopathy, septal lines, centrilobular ground glass opacities and bilateral small pleural effusions. Ventilation-perfusion scan did not reveal any segmental or sub-segmental perfusion defects. Elevated resting pulmonary arterial systolic pressure of 96 mmHg was found on echocardiography.The left ventricular ejection fraction was normal and there was no valvular pathology or intra-cardiac shunt. Pulmonary function test revealed normal FVC 2.75 liters (84% of predicted) and FEV1 2.04 liters (85% of predicted) with reduced DLCO 42% of predicted, consistent with pulmonary vascular disease. Thyroid function test, HIV serology and autoimmune screen were negative. Right heart catheterization was performed which confirmed elevated mean pulmonary artery pressure 67 mmHg, normal mean pulmonary capillary wedge pressure (PCWP) 7mmHg and cardiac index 2.93 l/min. Since the overall findings suggested pulmonary veno-occlusive disease (PVOD), vasodilator testing was not conducted. Therapeutic options including lung transplantation were discussed with the patient. He declined and was discharged home with oxygen. DISCUSSION: PVOD is a rare clinical entity and must be considered in the evaluation of severe pulmonary hypertension. Although definitive diagnosis is achieved by surgical lung biopsy, operative risks often prove to be prohibitive in these patients. This highlights the importance of typical CT scan findings in establishing the diagnosis presumptively yet confidently. The treatment of choice is lung transplantation. However, the role of anticoagulation and vasodilator therapy, which stem from extrapolation of care from idiopathic pulmonary arterial hypertension, remain controversial. CONCLUSIONS: The diagnosis of PVOD was based on presence of severe pulmonary hypertension, normal PCWP and characteristic CT features of septal lines, centrilobular ground glass opacities and bilateral small pleural effusions consistent with pulmonary edema.