A case of pulmonary arteriovenous fistula

: A 31-year-old man presenting with abrupt onset of convulsions was transported by ambulance to a nearby neurosurgery hospital. Imaging examination of the brain revealed a brain abscess in the left parietal lobe. Surgical excision of the abscess was performed. After the operation, the patient was referred to our hospital because of abnormal radio-opacities on the chest X-ray film, which were subsequently diagnosed to represent pulmonary arteriovenous fistulae in the lower lobes of both lungs. The fistulae were successfully embolized with detachable coils. Orthodeoxia (worsening of hypoxemia on assuming the upright from the supine position) was confirmed by measuring the partial pressure of oxygen in the arterial blood. We examined the shunt ratio by both the 100% O2 inhalation and 99mTc-MAA methods, and a higher ratio was obtained with the radioisotope method than with the 100% O2 inhalation method. Although it is known that the 99mTc-MAA method is more precise than the 100% O2 inhalation method, the latter is easier to perform and therefore more useful in practical clinical situations.