Portal de Periódicos da CAPES

Pulmonary Arteriovenous Malformations, Aneurysms and Reflections

1986; Elsevier BV; Volume: 89; Issue: 6 Linguagem: Inglês

10.1378/chest.89.6.771

1931-3543

Conor M. Burke, Thomas A. Raffin,

Congenital Heart Disease Studies

Almost 100 years have elapsed since Churton described the anatomic findings in a 12-year-old boy with multiple pulmonary arteriovenous aneurysms (PAVA).1Churton T Multiple aneurysms of pulmonary artery.Br Med J. 1897; 1: 1223Google Scholar Since then, about 500 cases have been reported in the literature.2Prager RL Laws KH Bender Jr, HW Arteriovenous fistula of the lung.Ann Thorac Surg. 1983; 26: 231-239Abstract Full Text PDF Scopus (97) Google Scholar Notwithstanding this experience, basic questions concerning terminology, etiology, diagnosis, optimal management and natural history still deserve consideration. Nomenclature is confused by the plethora of descriptive terms (including aneurysm, fistula, malformation, angioma, hamartoma and hemangioma) which are often used imprecisely. In addition, studies which demonstrate the passage of particles many times larger than pulmonary capillaries through the normal pulmonary vascular bed support the concept that functional arteriovenous connections exist in the normal lung, despite the failure to demonstrate such vessels morphologically.3Wagenvoort CA Wagenvoort N Pulmonary vascular bed: normal anatomy and responses to disease.in: Moser K.M. Pulmonary vascular diseases. Marcel Dekker Inc, New York1979Google Scholar It has been suggested that such passages may serve as safety valves to protect the capillary bed from pathologic increases in pressure or flow. While recognizing that present understanding is incomplete, it seems reasonable to suggest that the term “pulmonary arteriovenous malformation” (PAVM) be used to include both arteriovenous connections visible on angiographic examination (PAVA) and those rare microscopic arteriovenous communications associated with abnormal intrapulmonary shunting which are too small to be visualized radiographically. This terminology, pragmatic rather than scientific, does not exclude the possibility (suggested by physiologic principles and clinical experience) that initially microscopic arteriovenous connections may enlarge with time, eventually reaching macroscopic proportions. Indeed, such a sequence may explain the delayed clinical presentation of many patients with this congenital disease. In two recent series,4Dines DE Seward JB Bernatz PE Pulmonary arteriovenous fistula.Mayo Clin Proc. 1983; 3258: 176-181Google Scholar,5Dines DE Arms RA Bernatz PE Comes MR Pulmonary arteriovenous fistulas.Mayo Clin Proc. 1974; 49: 460-465PubMed Google Scholar mean age at diagnosis was 39 and 41 years. The reciprocal relationship between PAVA and Osler-Weber-Rendu disease (OWRD) is well-documented; in one large series,6Bosher Jr, LH Blake DA Byrd BR An analysis of the pathologic anatomy of pulmonary arteriovenous aneurysms with particular reference to the applicability of local excision.Surgery. 1959; 45: 91-104PubMed Google Scholar 36 percent of patients with single PAVA and 57 percent of those with multiple lesions had OWRD. Conversely, 15 percent of 91 members of a family with OWRD had PAVA.7Hodgson CH Burchell HB Good CA Claggett OT Hereditary hemorrhagic telangiectasia and pulmonary arteriovenous fistula; study of a large family.N Engl J Med. 1959; 26: 625-636Crossref Scopus (149) Google Scholar Patients with coexistent OWRD have an increased incidence of multiple PAVA and a higher rate of complications. Acquired PAVA are rare, but have been reported in association with cirrhosis, carcinoma, trauma, chest surgery, actinomycosis and schistosomiasis.2Prager RL Laws KH Bender Jr, HW Arteriovenous fistula of the lung.Ann Thorac Surg. 1983; 26: 231-239Abstract Full Text PDF Scopus (97) Google Scholar The role of noninvasive procedures in the diagnosis of right-to-left shunting deserves emphasis. Both contrast echocardiography and perfusion lung scintigraphy are useful screening procedures since a negative result excludes the presence of right-to-left shunting and a positive result confirms the diagnosis without risk to the patient. Scintigraphic examination has the advantage of providing a quantitative estimation of the magnitude of the shunt. One of these procedures should be performed prior to angiographic study in all cases and may be an important diagnostic clue in those rare patients with microscopic arteriovenous connections. Nevertheless, pulmonary angiography still remains the diagnostic gold standard for PAVA. In surgical candidates, angiographic examination is mandatory not only to establish the diagnosis, but also to exclude the presence of additional lesions and provide details of arterial supply and venous drainage. In patients unsuitable for or unwilling to undergo definitive treatment, scintigraphic or echocardiographic study should be conducted to confirm the clinical suspicion of PAVM. Management options for PAVA include occlusion by embolotherapy, surgical excision, or deferral of treatment pending the onset of complications such as hypoxemia, dyspnea, hemoptysis, hemothorax or brain abscess. As is often the case in clinical medicine, decision-making is hampered by the paucity of relevant data; ie, long-term outcome in untreated patients vs those subjected to occlusion or excision procedures. The sine qua non for informed decision-making, a clinical trial, seems unlikely to be carried out given the rarity of the condition, the duration of follow-up necessary and current perceived priorities. However, a review of the limited data available5Dines DE Arms RA Bernatz PE Comes MR Pulmonary arteriovenous fistulas.Mayo Clin Proc. 1974; 49: 460-465PubMed Google Scholar,8Yater WM Finnegan J Griffin HM Pulmonary arteriovenous fistula varix.Review of the literature and report of 2 cases. JAMA. 1949; 141: 581-589Google Scholar-12Sluiter-Eringa H Orie NGM Sluiter HJ Pulmonary arteriovenous fistula: diagnosis and prognosis in non-compliant patients.Am Rev Respir Dis. 1969; 100: 177-188PubMed Google Scholar suggests that the natural history of untreated PAVA is far from benign. Thus, the recent series of Dines et al5Dines DE Arms RA Bernatz PE Comes MR Pulmonary arteriovenous fistulas.Mayo Clin Proc. 1974; 49: 460-465PubMed Google Scholar is consistent with previous studies in documenting 11 percent mortality from complications directly related to PAVA and clinical progression in an additional 26 percent of untreated patients followed for a mean of six years. Complications reported after surgical excision are considerably less frequent than those in untreated patients4Dines DE Seward JB Bernatz PE Pulmonary arteriovenous fistula.Mayo Clin Proc. 1983; 3258: 176-181Google Scholar-6Bosher Jr, LH Blake DA Byrd BR An analysis of the pathologic anatomy of pulmonary arteriovenous aneurysms with particular reference to the applicability of local excision.Surgery. 1959; 45: 91-104PubMed Google Scholar and no mortality and minimal morbidity have been recorded following embolotherapy. It therefore appears that embolic occlusion of PAVA, first reported in 1978,13Taylor BG Cockerill EM Manfredi F Klatte EC Therapeutic embolization of the pulmonary artery in pulmonary arteriovenous fistula.Am J Med. 1978; 64: 360-365Abstract Full Text PDF PubMed Scopus (95) Google Scholar is the current treatment of choice in institutions with the necessary expertise and experience, notwithstanding the unavoidable absence of long-term follow-up of patients treated in this way. A recent review provides a detailed discussion of the various embolic techniques currently available, including both coil and balloon occlusion procedures.14White RI Embolotherapy in vascular disease.AJR. 1984; 142: 27-30Crossref PubMed Scopus (23) Google Scholar Although treatment, in general, should be offered once the diagnosis of PAVA is secure, some limited evidence suggests that the risk of progression or complications in asymptomatic individuals with single small lesions and no OWRD may be minimal.5Dines DE Arms RA Bernatz PE Comes MR Pulmonary arteriovenous fistulas.Mayo Clin Proc. 1974; 49: 460-465PubMed Google Scholar,12Sluiter-Eringa H Orie NGM Sluiter HJ Pulmonary arteriovenous fistula: diagnosis and prognosis in non-compliant patients.Am Rev Respir Dis. 1969; 100: 177-188PubMed Google Scholar In these cases, it would be reasonable to defer treatment pending evidence of progression. However, it should be emphasized that the evidence to support such a policy of non-intervention is based on a limited number of patients followed for a limited time. Thus, after almost one century since Churton's first report of PAVA, we continue to strive for increased documentation of the long-term outcome of patients with PAVA. It is only in this way that an accurate picture of the natural history of this enigmatic disease and the consequences of the various treatment modalities will emerge.