Study objectives: To assess the effectiveness of pulse
oximetry and radioisotope measurement of right-to-left (R-L) shunt for
the early detection of pulmonary arteriovenous malformations (PAVMs) in
patients with hereditary hemorrhagic telangiectasia (HHT).
Design: Patients with HHT had serial measurements of the
following: (1) arterial oxygen saturation
(Sao2) by pulse oximetry in erect and supine
positions, and on maximal exercise using cycle ergometry; (2)
quantitative radioisotope measurements of R-L shunt using IV
99mTc-labeled macroaggregates of albumin; and (3) routine
pulmonary function. After percutaneous transcatheter embolization of
all PAVMs with feeding vessel diameters > 3 mm, residual PAVMs were
assessed with selective digital subtraction pulmonary angiography.
Using postembolization angiography as the “gold standard,”
Sao2 and radioisotope shunt measurements after
embolization were analyzed retrospectively using logistic regression to
assess the ability of each test to predict for the presence of residual
Results: Of the 66 patients included, 40 had
small PAVMs remaining postembolization. Using univariate logistic
regression, radioisotope shunt and erect saturation showed a
significant relationship with the presence of residual PAVMs
(p = 0.001, 0.005, respectively). Erect Sao2≤
96% had 73% sensitivity and 35% specificity for detecting PAVMs.
Radioisotope shunt >3.5% of cardiac output had 87% sensitivity and
61% specificity for detecting PAVMs.
These results confirm that noninvasive measurements are useful in the
screening of patients with HHT for the presence of PAVMs without need
for angiography and its associated risks, and that radionuclide
scanning is better than pulse oximetry.
Abbreviations: CE = contrast
echocardiography; HHT = hereditary hemorrhagic telangiectasia;
PAVM = pulmonary arteriovenous malformation;
Sao2 = arterial oxygen saturation; R-L
shunt = right to left shunt;
99mTc-MAA = 99mtechnetium-labeled
macroaggregates of albumin