Unusual Congenital Pulmonary Anomaly in an Adult Patient With Dyspnea

Anatomic variations may result in abnormal return from the pulmonary veins to the right side of the heart. This group of congenital anomalies, also known as partial anomalous pulmonary venous return (PAPVR), may connect oxygenated blood from the pulmonary vein to a systemic vein before reaching the right atrium. The most common PAPVR is derived from the left upper pulmonary vein, which then connects to the left innominate vein and drains into the superior vena cava (SVC).

Scimitar syndrome is a rare PAPVR variant in which part of or the entire right lung is drained by the pulmonary vein into the inferior vena cava (IVC), giving the curvilinear dimension the appearance of a Middle Eastern sword (scimitar). The syndrome is frequently associated with other abnormalities, such as right lung hypoplasia and abnormal right lung lobation, dextroposition of the heart, right pulmonary artery hypoplasia, systemic arterial blood supply to the right lower lung from the infradiaphragmatic aorta, atrial septal defects of the secundum type, right-sided diaphragmatic hernia, and horseshoe lung.^1,2 The syndrome was first described in 1836 by Cooper during an autopsy of an infant, and Dotter diagnosed the first symptomatic patient in 1949.^3,4

Case Report

A 62-year-old man, former smoker (40 pack-year), with a past medical history of arterial hypertension and asthma visited the clinic, reporting exertional dyspnea. He also reported oppressive, retrosternally located exertional chest pain, 6/10 in intensity, of 3 minutes’ duration that radiated to the right chest and ameliorated with rest. Symptoms had occurred every other day for the past year. His physical exam was remarkable for central obesity. Lung auscultation was essentially clear. There was no jugular vein distention. The patient’s heart showed a regular rate and rhythm without evidence of murmurs or gallops. There was no evidence of leg edema or cyanosis. The patient’s resting oxygen saturation of 98% remained unchanged after exercise.

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An electrocardiogram showed normal sinus rhythm with no ischemic changes. A pulmonary function test showed a forced expiratory volume (FEV₁) of 1.44 L (61% of predicted), forced vital capacity (FVC) of 1.99 L (68% of predicted), and slow vital capacity (SVC) of 2.09 L (60% of predicted), with an FEV₁/SVC ratio of 68% of predicted. These results suggested moderate-to-severe obstructive ventilatory impairment.

There was no response to bronchodilator therapy. Lung volumes were measured by plethysmography. The residual volume (RV), total lung capacity (TLC), and RV/TLC ratio were 2.57 L (147% of predicted), 4.66 L (88% of predicted), and 55%, respectively, suggesting severe air trapping. Diffusion lung capacity (DLCO) testing revealed 16.95 mL/min/mm Hg (73% of predicted) when corrected by hemoglobin and DLCO/alveolar volume of 4.97 mL/min/mm Hg/L (114% of predicted). This result was consistent with a mild reduction of gas transfer, which normalized when corrected by alveolar volume.

A posteroanterior chest radiograph image was remarkable for mediastinal shifting toward the right side, volume loss of the right lung, and evidence of a previous gunshot on the right chest wall (Figure 1). Previous chest imaging done in October 2009 showed an opacification of the right lower lung with indistinctness of the right cardiac border and partial obliteration of the right hemidiaphragm. The patient was treated with inhaled steroids and long- acting bronchodilators with partial improvement in dyspnea symptoms.

Myocardial perfusion imaging revealed scintigraphic evidence of heart rate-induced ischemia on the inferior and apical wall segments of the left ventricular myocardium. A transthoracic echocardiogram showed a very poor echocardiographic window. Left ventricular function seemed preserved. Transesophageal echocardiography was scheduled, but the patient missed the appointment.

Cardiac catheterization was only remarkable for 40% to 50% obstruction of the mid-left anterior descending artery, which did not explain the patient’s dyspnea or chest pain. Right side pressures were described as follows: right atrial mean, 10 mm Hg; right ventricle, 36/8 mm Hg; pulmonary artery, 33/16 mm Hg; pulmonary artery mean, 23 mm Hg; pulmonary capillary wedge pressure, 12 mm Hg; and a mean arterial pressure of 100 mm Hg. He had a left ventricle ejection fraction of 60%.

Because images suggested dextroposition of the heart and right lung hypoplasia, a chest computed tomography (CT) and angiography were done (Figure 2). The images showed hypoplasia of the right lung field with an anomalous venous return from the right midlung, having a vertical contour that drained into the supradiaphragmatic IVC. In addition, CT reconstruction demarcated the last mentioned contour draining into the IVC, consistent with scimitar syndrome (Figure 3). The patient was treated conservatively due to age, optimizing therapy for obstructive lung and cardiovascular disease.