Pulmonary arteriovenous malformations: diagnosis

Abstract

Pulmonary arteriovenous malformations (PAVMs) are rare, abnormal low resistance vascular structures that connect a pulmonary artery to a pulmonary vein, thereby bypassing the normal pulmonary capillary bed and resulting in an intrapulmonary right-to-left shunt. The spectrum of PAVMs extends from microscopic lesions causing profound hypoxemia and ground glass appearance on computed tomography (CT) but with normal catheter angiographic findings to classic pulmonary aneurysmal connections that abnormally connect pulmonary veins and arteries. These malformations most commonly are seen in hereditary hemorrhagic telangiectasia (HHT). They are rarely due to secondary conditions such as post congenital heart disease surgery or hepatopulmonary syndrome (HPS). The main complications of PAVM result from intrapulmonary shunt and include stroke, brain abscess, and hypoxemia. Local pulmonary complications include PAVM rupture leading to life-threatening hemoptysis or hemothorax. The preferred screening test for PAVM is transthoracic contrast echocardiography (TTCE). CT has become the gold standard imaging test to establish the presence of PAVM. Endovascular occlusion of the feeding artery is the treatment of choice. Collateralization and recanalization of PAVM following treatment may occur, and hence long term clinical and imaging follow-up is required to assess PAVM enlargement and PAVM reperfusion.

Pulmonary arteriovenous malformation: Case report

“…Pathologic pulmonary arteriovenous malformation is the direct communication between the branches of pulmonary artery and pulmonary vein in way that there is a shunts of normal lung capillaries which leads to chronic hypoxia 1,2,4 . The incidence of PAVM is 2-3 cases in 100.000 people 1,5,6 .…”

“…They are stabile in 75% of the cases or slow growth, and only in small number of cases PAVM can induce higher rate of morbidity and mortality because of no treatment 10 . Complications are brain abscess, stroke, hemoptysis and haemothorax, hypoxia, polycythemia, endocarditis, transitory ischemic attack, migraine and congestive hearth weakness 1,4,6 . Risk of neurological complications is higher in diffuse type PAVM, large shunt and feeding branch diameter more than 3 mm 11 and in untreated forms of PAVM in comparation to treated forms 4 .…”

“…Typically patients with hereditary telangiectasia are examined; they undergo screening radiographic procedures PAVM is discovered in about 15% of cases 4 . There was 90% chance of discovering hereditary telangiectasia with patients that had been initially diagnosed with PAVM and who were send on further investigation.…”

“…Because of that it is important that every patient with suspected PAVM undergo detailed and targeted diagnostic. It means that before visiting the interventional radiologist some other investigations have to be done: multidisciplinary clinical evaluation, imaging for endovascular embolization (number of lesions, localization and type of PAVM, as well as measured diameter of feeding/s arteries), anesthetic assessment for the type of anesthesia, EKG (searching for the block of the left branch and hypertrophy of right ventricle), complete blood count, coagulation status and other laboratory analyses, it is also important to have patient informed confirm 4 . Gold standard in diagnosing the PAVM is MSCT pulmonary angiography.…”

“…Main indications for treating PAVMs with endovascular approach are: PAVM with diameter of feeding artery greater than 2 mm, which can be treated with endovascular approach, symptomatic PAVM no matter what size it is and atypical lesion that is similar to PAVM on MSCT and presence of suggestive symptoms 4 .…”