Andersons pediatric cardiology 745

A single right pulmonary vein RPV can be seen draining the right lung, with a connection to the inferior caval vein ICV.. It is important to distinguish between partially anomalous conne

FIG 28.30 Computed tomographic angiogram performed in a patient with

scimitar syndrome and reconstructed to include the pulmonary parenchyma

in addition to the vasculature A single right pulmonary vein (RPV) can be

seen draining the right lung, with a connection to the inferior caval vein

(ICV) Note the size of the pulmonary valve (PV) in comparison to the aorta

(AO) A small aortopulmonary collateral to the right lung (arrow) originating

below the diaphragm can also be seen RA, Right atrium; RV, right

ventricle F, Feet; H, head; L, left; R, right.

It is important to distinguish between partially anomalous connection to a left vertical vein and persistence of the left superior caval vein Traditionally, the characteristic finding by MRI was a lateral “break” in the complete ring created

by fat surrounding the superior caval vein in the transverse plane.155 However, three-dimensional reconstructions (Fig 28.31) and flow analysis using MRI make this distinction much more straightforward

FIG 28.31 Magnetic resonance imaging in a patient with partially anomalous pulmonary venous drainage (A) Three-dimensional reconstruction of a magnetic resonance angiogram revealing an anomalous connection of the left upper pulmonary vein (LUPV) to the left

brachiocephalic vein (BCV) The left lower pulmonary vein (LLPV) is

connected normally (B) Steady-state free precession cine image in a short-axis plane Note the size of the dilated right ventricle (RV) in comparison to

the left ventricle (LV) A stack of these short-axis images can be traced to

provide end-systolic and diastolic volumes of the ventricles In this patient,

the right ventricle is traced in red and the left ventricle in green, using

commercially available software.

Cardiac Catheterization and Angiocardiography

Cardiac catheterization is rarely indicated for these patients A combination of noninvasive imaging techniques, if performed, will document the

pathophysiology already described In diagnosing partially anomalous

pulmonary venous connection, a step-up in oxygen saturation in the superior caval vein, the innominate vein, or the inferior caval vein is suggestive of

anomalous pulmonary veins draining into the respective sites.156 Entry to the anomalous veins may be achieved as for TAPVC In patients with scimitar

syndrome and a hypoplastic right lung, measurement of oxygen saturations in the anomalous right pulmonary veins could be helpful when deciding whether to pursue surgery, as repair is unlikely to be advantageous in patients with

pulmonary venous desaturation

To demonstrate drainage outside the heart, pulmonary arteriography and selective pulmonary venous angiograms may be performed as for TAPVC (Fig

sufficient to fully document anomalous pulmonary venous drainage, particularly anomalous drainage from the right lower lobe In the case of the scimitar

syndrome, selective injection of the systemic arterial supply to the lungs is also essential (see Fig 28.32B) Along these lines, if there is a dual arterial supply (both systemic and pulmonary) to any portion of the lung, embolization of the aortopulmonary collateral in the catheterization laboratory should be considered

FIG 28.32 Selective angiography in scimitar syndrome displayed in the

frontal projection (A) Pulmonary arteriogram, filmed in its late stages, demonstrates that the pulmonary veins return by two routes to the heart:

one a tortuous vein to the right atrium, and one a descending pulmonary

vein to the inferior caval vein (B) Selective injection into a branch of the

descending aorta demonstrates the anomalous systemic arterial supply to

the right lower lobe.

Differential Diagnosis

The main differential diagnosis is an atrial septal defect in the oval fossa, which has already been discussed at length In most cases, particularly when associated with an atrial septal defect, it is not critical that the anomalous connection be diagnosed preoperatively, since surgery can usually be adjusted accordingly Therefore invasive investigation of a typical atrial septal defect is not justified simply to rule out a partially anomalous pulmonary venous connection The only possible exception is connection of both left pulmonary veins to a vertical vein