Definitive Diagnosis of Pulmonary Artery Sling in a Critically Ill Infant With High-Resolution Computed Tomography
A 3-month-old infant was transferred to our hospital for evaluation of a heart murmur associated with severe respiratory distress. At echocardiography, an aberrant origin of the left pulmonary artery was suspected (Figure 1, Movies I and II).
As cardiac catheterization was regarded as hazardous in this critically ill infant, we performed cardiac computed tomography (CT) scanning with a LightSpeed VCT (General Electric, Milwaukee, USA) (slice thickness 0.625 mm × 64, speed rotation 0.4 sec, pitch 0.9, 80 kV, mA modulated during the acquisition, after peripheral injection of contrast agent [Iohexol 300 mgI/mL, volume of 1.5 mL/kg, flow rate of the injection of 0.5 mL/sec]). The acquisition lasted 1.2 seconds and the examination lasted approximately 15 minutes in total.
The CT scan confirmed the diagnosis of an abnormal origin of the left pulmonary artery (Figures 2 and 3⇓, Movie III). The latter was arising from the right pulmonary artery and passed posterior to the trachea, resulting in a pulmonary artery sling. This abnormal course of the left pulmonary artery led to a tight compression of the tracheal bifurcation and of the origin of the left main bronchus.
The left pulmonary artery was successfully transferred to the pulmonary trunk anterior to the trachea without the need for any tracheoplasty. Postoperative recovery was uneventful.
Traditionally, the diagnosis of pulmonary artery sling is based on conventional angiography. These images demonstrate the valuable diagnostic utility of high resolution CT scanning as an alternate non-invasive modality in this clinical situation.
The online-only Data Supplement, which contains Movies I through III, can be found at http://circ.ahajournals.org/cgi/content/full/115/15/e398/DC1.