What is the appropriate size criterion for resection of thoracic aortic aneurysms?

Abstract

Although many articles have described techniques for resection of thoracic aortic aneurysms, limited information on the natural history of this disorder is available to aid in defining criteria for surgical intervention. Data on 230 patients with thoracic aortic aneurysms treated at Yale University School of Medicine from 1985 to 1996 were analyzed. This computerized database included 714 imaging studies (magnetic resonance imaging, computed tomography, echocardiography). Mean size of the thoracic aorta in these patients at initial presentation was 5.2 cm (range 3.5 to 10 cm). The mean growth rate was 0.12 cm/yr. Overall survivals at 1 and 5 years were 85% and 64%, respectively. Patients having aortic dissection had lower survival (83% 1 year; 46% 5 year) than the cohort without dissection (89% 1 year; 71% 5 year). One hundred thirty-six patients underwent surgery for their thoracic aortic aneurysms. For elective operations, the mortality was 9.0%; for emergency operations, 21.7%. Median size at time of rupture or dissection was 6.0 cm for ascending aneurysms and 7.2 cm for descending aneurysms. The incidence of dissection or rupture increased with aneurysm size. Multivariable regression analysis to isolate risk factors for acute dissection or rupture revealed that size larger than 6.0 cm increased the probability by 32.1 percentage points for ascending aneurysms (p = 0.005). For descending aneurysms, this probability increased by 43.0 percentage points at a size greater than 7.0 cm (p = 0.006). If the median size at the time of dissection or rupture were used as the intervention criterion, half of the patients would suffer a devastating complication before the operation. Accordingly, a criterion lower than the median is appropriate. We recommend 5.5 cm as an acceptable size for elective resection of ascending aortic aneurysms, because resection can be performed with relatively low mortality. For aneurysms of the descending aorta, in which perioperative complications are greater and the median size at the time of complications is larger, we recommend intervention at 6.5 cm.

Diretrizes para a cirurgia das doenças da aorta

“…Em relação a aneurismas localizados no arco transverso, as indicações atualmente aceitas para ressecção cirúrgica incluem: 1º) diâmetro absoluto > 6 ou 7 cm, ou superior ao dobro do diâmetro esperado para aquele indiví-duo; 2º) crescimento no diâmetro superior a 7 ou 10 mm por ano; 3º) dor ou sintomas compressivos e 4º) aneurismas saculares 137,138 . Pacientes com síndrome de Marfan em geral têm cirurgia indicada mais precocemente, com crescimento superior a 3 ou 5mm por ano, ou diâmetro absoluto de 5cm 139 .…”

“…Neste sentido, alguns complicados modelos de equações exponenciais têm sido propostos para cálculo da estimativa de eventos agudos em casos de AAD 140,141 . O grupo da Yale University tem realizado estudos evolutivos consistentes e simplificados 77,133,142,143 , apontando o diâmetro como o mais relevante fator independente de risco para complicações. Com base em um banco de dados de 721 pacientes com AAD, os autores acompanharam a evolução de 304 casos assintomáti-cos, com diâmetro mínimo de 3,5cm, e demonstraram claramente que a incidência de desfechos associados -ruptura, dissecção ou óbito -foi de 15,6% para aneurismas com diâ-metro ?…”

Cardiovascular Magnetic Resonance in Marfan Syndrome

“…However the increasing incidence of a poor outcome after emergency surgery versus the low mortality of less than 2% for elective aortic replacement was already recognised and increasing numbers of surgeons were performing prophylactic root replacement at a diameter of 5.5 -6.0 cm. Some groups in the late 1990's were proposing a further reduction of this value to 5.0 -5.5 cm [54][55][56].…”

Local mechanical properties of human ascending thoracic aneurysms

“…Surgical repair is only indicated when the diameter of the aneurysm exceeds 5.5 cm. However, aneurysms with diameters greater than the surgical threshold may remain stable [1,3,18] and conversely, small aneurysms (< 4.5 cm) do rupture [1,4,18]. Rupture is a localized phenomenon and to identify potential rupture locations in advance, one must consider the local mechanical conditions of the tissue.…”