PED2 Absent right pulmonary artery in a child presenting with pneumonia. (Pediatrics & Adolescent Medicine).

PED2 ABSENT RIGHT PULMONARY ARTERY IN A CHILD PRESENTING WITH PNEUMONIA. D. Howell, H. Whitley, and S. Inscore. Department of Pediatrics, Wilford Hall Medical Center, San Antonio, Tex.

Absent right pulmonary artery (ARPA) is rare as an isolated cardiac anomaly, and has a wide variety of clinical presentations, ranging from life-threatening symptoms of congestive heart failure with severe pulmonary hypertension to incidental findings on chest x-ray (CXR). We present a case associated with recurrent pneumonia in a child. A white boy almost 4 years old was admitted for pneumonia. On examination, his vital signs revealed T 103, RR 40, P 100, BP 107/60 (right arm) mm Hg, [O.sub.2] sats 92% on room air. Intermittent expiratory wheezes were noted on exam. Oxygen, albuterol, and antibiotics were given, and a CXR was obtained, which showed asymmetrically inflated lungs, shift of the mediastinum to the right, hyperaeration of the left, with no evidence of foreign body. He had previous diagnoses of pneumonia without hospitalization, but there was no mention of other abnormal CXR findings in the past. The patient's respiratory symptoms resolved over three days in the hospital, but his CXR remained unch anged. Differential diagnosis of an anterior pneumothorax versus a hypoplastic right lung was considered, and a CT of the chest was obtained to further delineate the process, which revealed a hypoplastic appearing right lung, possibly secondary to pulmonary artery hypoplasia or agenesis (main and left pulmonary arteries were identified). Cardiac exam showed normal precordial activity, normal S1, single S2, and a II-III/VI SEM heard along the left sternal border with soft radiation to the axilla and back. An EKG was performed which revealed normal sinus rhythm with a rate of 95, QRS axis of +80, and an incomplete right bundle branch block (thought to be a normal variant). On echocardiogram he was noted to have normal ventricular function and septal motion bilaterally, possibly mild dilation of the right ventricle. Left pulmonary artery Doppler velocity was mildly increased at 2.0 L per second with a diameter of at least 10 mm, but the right pulmonary artery was not seen. Aorta and inferior vena cava were noted to be normal; pulmonary veins were not appreciated from the right lung. A limited exercise tolerance test was performed: pulse 100, [O.sub.2] sats 98% prior to exercise, pulse 176, [O.sub.2] sats 95% after exercise. With concerns of elevated pulmonary pressures, a cardiac catheterization was performed. This revealed normal pulmonary venous return on the left with a large left pulmonary artery, no evidence of a right pulmonary artery, and small bronchial collateral vessels from the aorta that provided blood flow to the right lung. Main pulmonary artery pressure was somewhat elevated to 30/12. With a diagnosis of absent right pulmonary artery without significant pulmonary hypertension, the child is now being followed up periodically as an outpatient. Patients with ARPA can be divided into three groups: the first is associated with a left to right shunt; the second group is associated with an isolated ARPA and pulmonary hypertension; the third group has an isolated ARPA without pulmonary hypertension. The first group is usually associated with cardiovascular anomalies such as Tetralogy of Fallot, septal defects, and patent ductus arteriosis. In these cases, the diagnosis is made with surgical correction usually performed in the first year of life because they present with congestive heart failure and respiratory problems in infancy. The second group also often presents in early infancy with pulmonary hypertension, thought to have occurred secondary to augmented pulmonary flow prior to regression of the fetal pulmonary vascular pattern. The patient described in the case above fits into the third group. ARPA is less common without associated cardiac anomalies, and in these cases is often associated with a benign clinical course. Pulmonary hypertension occurs in only about 20% of cases with isolated ARPA, with most of these presenting in the first few months of life. Hemoptysis in isolated ARPA occurs in less than 10%, and rarely patients present with a history of recurrent pulmonary infection, pain in the chest, dysp nea on exertion, or cyanosis. Physical examination findings are usually unremarkable except for decreased breath sounds on the affected side. EKGs and blood gases are often normal. For those without pulmonary hypertension or more severe symptoms, there are characteristic CXR findings, first described in 1954 by Wyman. They include cardiac and mediastinal displacement, absence of the pulmonary arterial shadow, smaller hemithorax, elevation of the hemidiaphragm, and decreased vascular markings, all on the involved side. Hyperinflation and herniation of the lung across the midline is often seen on the opposite side. Other diagnostic studies include cardiopulmonary exercise testing which may show an increase in percent dead space during exercise in the absence of pulmonary hypertension and associated cardiac disease; ventilation-perfusion scanning shows normal ventilation bilaterally, with complete absence of perfusion on the involved side; angiography shows the anatomical absence of the pulmonary artery with lun g blood flow provided from collateral circulation. The outcome of ARPA depends heavily on associated findings of pulmonary hypertension or other cardiac anomalies. Without the development of pulmonary hypertension, a patient can typically live a full and complete life without sequelae from this diagnosis.