Thoracic Imaging 2003 - Society of Thoracic Radiology

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7.5 mm) than the inferior pulmonary veins (14.0 ± 6.2 mm).
There is no significant difference between the average diameters
of the right and left pulmonary vein ostia, (mean of 18.0 ± 3.7
mm). The superior pulmonary veins are typically larger than the
inferior pulmonary veins [3, 16, 17]. The most common
anatomic variant, the right middle pulmonary vein, has an ostial
diameter significantly smaller than the other pulmonary veins
(9.9 ± 1.9 mm). When present, a common left pulmonary vein
trunk will have a diameter significantly larger than the other
pulmonary veins (32.5 ± 0.5 mm). In studies by Scharf, Sneider,
et al., and Tsau, Wu, et al., the pulmonary veins in patients with
atrial fibrillation were significantly larger than those of patients
without atrial fibrillation. There was no difference between the
size of veins in patients with paroxysmal versus persistent fibrillation.
Atrial fibrillation patients also had a left atrial surface
area greater than normal individuals [10, 11].
EFFECTS OF ABLATION ON OSTIAL DIAMETER
Several studies have shown that 40 – 100% of patients will
develop some degree of pulmonary vein stenosis following RF
ablation [6, 11, 12]. The vast majority have less than 10% stenosis,
and are completely asymptomatic with up to 68% luminal
stenosis. Severe stenosis is very rare, and to date there have
been only two reported cases of significant sequela from severely
symptomatic veno-occlusive disease and hemorrhagic pulmonary
venous infarction [7, 12].
SUMMARY
Radiofrequency ablation of arrhythmogenic foci within the
proximal veins has been repeatedly shown to be highly effective
for the treatment of paroxysmal and persistent atrial fibrillation.
Knowledge of the size and number of pulmonary veins is
important in planning a successful ablation procedure, since as
many as 20% of patients will display anatomic variations.
Imaging with multi-row CT is an effective and rapid method
providing this information. Although pulmonary venous stenosis
is a frequent complication of RF ablation, it is most usually
asymptomatic, even with stenosis of up to 68%. Complications
from severe stenosis are extremely rare. CT imaging facilitates
effective follow-up screening for pulmonary vein stenosis and
assessment of severity and progression.
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