Why So Blue? Successful Treatment of Refractory Hypoxemia in a Patient With Polycythemia Vera-Associated Pulmonary Arterial Hypertension and a Patent Foramen Ovale

Abstract

INTRODUCTION: Polycythemia vera (PV) is associated with hypercoagulability and increased risk of multifactorial pulmonary hypertension (PH). There are two distinct phenotypes in PV-related PH, including an early presentation with chronic thromboembolic pulmonary hypertension (CTEPH) and a late presentation mimicking pulmonary arterial hypertension (PAH).1 Little is known about the treatment of PAH in the setting of PV. CASE PRESENTATION: Mr. R is a 70 year old with a 13-year history of PV treated with hydroxyurea and phlebotomy, coronary artery disease, and a remote history of deep venous thrombosis treated with warfarin until he developed a diverticular bleed 2 months prior who presented with new onset dyspnea, abdominal pain, and severe hypoxia. Exam revealed a saturation of 52% on room air, improved to 91% on 100% FiO2, with nonlabored respirations and clear lung fields; abdomen was distended with hepatosplenomegaly. A ventilation-perfusion scan was low probability for pulmonary embolus. CT showed minimal atelectasis in the left base with no infiltrates or pulmonary embolus, and hepatosplenomegaly with multiple splenic infarcts. Echocardiogram revealed a patent foramen ovale (PFO) with right-to-left shunt, reduced right ventricular (RV) systolic function, and RV systolic pressure of 45-50 mmHg (see Image 1). Right heart catheterization identified a pulmonary artery pressure (PAP) of 57/25 mmHg (see Table 1). Systemic cardiac output (CO) was 6.1 L/min and pulmonary CO was 4.5 L/min, confirming significant shunt through the PFO. Pulmonary vascular resistance was 7.34 Wood units, with a significant response to inhaled nitric oxide. Mr. R was started on sildenafil, with stable PAP but improved CO and oxygen requirements. Endovascular PFO closure was completed, and Mr. R was able to wean off oxygen; he remains on outpatient sildenafil therapy with improved exercise tolerance. DISCUSSION: This patient presented with refractory hypoxemia from significant shunting through a PFO due to late onset PV-related PAH. Initiation of PAH therapy with sildenafil was able to lower PAP enough to decrease the degree of right-to-left shunt and allow for safe endovascular closure of the PFO. Although presentation of PH with refractory shunt through a PFO is uncommon, if the PH can be successfully treated, partial or complete closure of the PFO may be considered. CONCLUSION(S): Initiation of sildenafil in this patient with PV-related PAH improved pulmonary hemodynamics and hypoxia enough to allow for PFO closure and weaning from oxygen. Treatment with PAH therapies such as sildenafil may be considered in this patient population.