Endovascular Aortic Repair

Clinical Relevance

Abdominal aortic aneurysms (AAAs) occur in approximately 5% to 10% of the male population older than 65 years, and the incidence increases with advancing age. The risk of rupture is very low for aneurysms less than 5 cm in diameter, but increases substantially with aneurysms larger than 6 cm in diameter. Mortality rates for traditional open repair of AAAs vary widely, depending on the operator’s experience. In the United Kingdom, the overall in-hospital mortality rates for open and endovascular elective treatment were, respectively, 3.1% and 0.6% in a 2017 report. It is higher in emergency cases.

Endovascular aneurysm repair (EVAR) was initially introduced with the aim of achieving lower mortality and morbidity rates in elderly and unfit patients deemed to be at greater risk for complications from conventional surgery. Since its introduction by Parodi almost two decades ago, EVAR has become widely used worldwide and is now the main method used to treat many patients with AAAs.

Indications

Selection of patients suitable for standard EVAR is usually made in a multidisciplinary context, weighing patients’ risk factors such as age > 70 years, coronary artery disease, respiratory disease, renal function, obesity, and the anatomic scenario.

Coronary artery disease in particular is considered the leading cause of mortality after open surgery because it is associated with high (>5%) risk of perioperative cardiovascular complications (myocardial infarction, stroke, and cardiac death).

The risk of contrast-induced nephropathy should also be taken into account, particularly in patients with an estimated glomerular filtration rate < 30 mL/min, diabetes mellitus, old age, reduced left ventricle systolic function, advanced heart failure, acute myocardial infarction, and shock.

Indications for treatment of AAAs with EVAR are the same as for conventional surgical repair.

• • Aneurysm diameter. Treatment of AAAs is based on the aneurysm reaching a size threshold above which leaving it untreated is more hazardous than treatment. The treatment threshold is based on the perceived annual rupture rate of aneurysms of different diameters. Although rupture rates of small aneurysms are very low, the rate increases to 10% per year once aneurysms reach 6 cm in diameter. The UK Small Aneurysm Trial (UKSAT) and the US Aneurysm Detection and Management (ADAM) study were conducted to discern optimal management of AAAs between 4.0 and 5.5 cm. Both studies concluded that surgery should be performed at a threshold diameter of 5.5 cm, and that surgery for smaller aneurysms provided no survival advantage. It remains controversial whether the 5.5-cm threshold should apply to women, and many interventionalists treat AAAs in women when they reach 5 cm, even less in some centers.

  • Symptomatic aneurysms. Painful or tender AAAs.

  • Rapidly growing aneurysms. AAAs with an increase in diameter ≥ 5 mm within 6 months.

Anatomic Inclusion Criteria for Endovascular Aneurysm Repair

Inclusion criteria for EVAR are based mainly on the anatomic features of the proximal aortic neck (distance between the lower renal artery and the aneurysm) to achieve a good sealing and of the iliofemoral axis for a safety introduction and removal of the stent-graft device.