Significant Endoleak Research Articles

Duplex ultrasound in aneurysm surveillance following endovascular aneurysm repair: a comparison with computed tomography aortography

Cumulative radiation dose, cost, and increased demand for computed tomography aortography (CTA) suggest that duplex ultrasonography (DU) may be an alternative to CTA-based surveillance. We compared CTA with DU during endovascular aneurysm repair (EVAR) follow-up. Patients undergoing EVAR had clinical and radiological follow-up data entered in a prospectively maintained database. For the purpose of this study, the gold standard test for endoleak detection was CTA, and an endoleak detected on DU alone was assumed to be a false positive result. DU interpretation was performed independently of CTA and vice versa. One hundred thirty-two patients underwent EVAR, of whom 117 attended for follow-up ranging from six months to nine years (mean, 32 months). Adequate aneurysm sac visualisation on DU was not possible in 1.7% of patients, predominantly due to obesity. Twenty-eight endoleaks were detected in 28 patients during follow-up. Of these, 24 were initially identified on DU (four false negative DU examinations), and eight had at least one negative CTA with a positive DU prior to diagnosis. Twenty-three endoleaks were type II in nature and three of these patients had increased sac size. There was one type I and four type III endoleaks. Two of these (both type III) had an increased sac size. Of 12 patients with increased aneurysm size of 5 mm or more at follow-up, five had an endoleak visible on DU, yet negative CTA and a further five had endoleak visualisation on both DU and CTA. Of six endoleaks which underwent re-intervention, all were initially picked up on DU. One of these endoleaks was never demonstrated on CTA and a further two had at least one negative CTA prior to endoleak confirmation. Positive predictive value for DU was 45% and negative predictive value 94%. Specificity of DU for endoleak detection was 67% when compared with CTA, because of the large number of false positive DU results. Sensitivity for DU was 86%, with all clinically significant endoleaks demonstrated on CTA also detected on DU. Despite its low positive predictive value, we found DU to be a sensitive test for the detection of clinically significant endoleaks. Given concerns about cumulative radiation exposure and cost, and the surprisingly low sensitivity of CTA for endoleak detection in this series, selective CTA based on DU surveillance may be a more appropriate long-term strategy.

Diastolic rotational flow in the aortic arch

WHILE the presence of rotational blood flow in the distal aortic arch is expected based upon modelling of the arch and has been demonstrated during cardiopulmonary bypass,1 the utility of echocardiography to characterize these flows has been the subject of debate.2 A 76-yr-old male successfully underwent endovascular exclusion of his descending thoracic aortic aneurysm. Transesophageal echocardiographic interrogation of the stent with colour Doppler did not reveal any clinically significant endoleaks and a completion echocontrast aortogram confirmed the absence of an endoleak. Clockwise rotational flow during diastole was demonstrated in the short axis view of the aortic arch at the level of the left subclavian artery (Figure, panels A and B; and video, available as Additional Material at: www.cja-cja.org). The long axis view demonstrated a similar, less well-developed rotational flow, with the flow reversal (retrograde flow) occurring along the posterior wall. Rotational flow, or even vortices, in the human aortic arch are expected as a consequence of the vessel’s shape and branching pattern. The existence of vortices has been difficult to prove, though recent magnetic resonance images have suggested longitudinal helical flow down the normal aorta with the development of vortices in the presence of even minor abnormalities.3 These images confirm that under some conditions rotational flow exists and can be visualized and quantified with transesophageal echocardiography and echocontrast. As there were no equivalent images prior to the stent deployment, we cannot exclude the possibility that this phenomenon is a consequence of the hemodynamic changes induced by the stent.

Endovascular treatment of endoleaks after endovascular abdominal aortic aneurysm repair: personal experience

This paper describes the different endovascular treatments (cuffs, endografts and embolisation) available for types I, II and III endoleaks occurring after endovascular abdominal aortic aneurysm repair (EVAR). From January 2000 to June 2006, 134 patients (118 men, 16 women; mean age 75.1 years) underwent EVAR. Ten patients (7%) developed significant endoleaks requiring endovascular treatment. Five endoleaks were type I, two were type II and three were type III. Of the five type I endoleaks, four were proximal and one was distal. The proximal endoleaks were treated by cuff deployment, whereas the distal endoleak was treated with a bifurcated graft. Of the two patients with type II endoleak, one was treated by translumbar puncture and coil embolisation, and the other was treated by superselective embolisation of the lumbar feeding vessel with nonresorbable particles. Of the three patients with type III endoleak, two were treated by deploying an aortouniiliac endograft inside the bifurcated graft and the other by implanting a cuff to restore continuity between the graft body and the contralateral limb. Endovascular treatment was successful in 6/10 cases, whereas three cases required surgical conversion. One patient did not undergo surgery owing to poor general condition. The reported incidence of endoleaks after EVAR is 10%-20%. Significant endoleaks should be treated promptly. Endovascular treatment can be done with different techniques, but success in not constant due to adverse anatomical conditions and technical difficulties.

Color Duplex Ultrasound Characteristics: Can we Predict Aortic Aneurysm Expansion following Endovascular Repair?

Introduction The goal of aortic endovascular repair (EVAR) is to successfully exclude the aneurysm. Color duplex ultrasonography (CDU) is effective in the identification of endoleak and assessment of abdominal aortic aneurysm (AAA) morphology after EVAR. In a subset of patients with subtle endoleak, there is a characteristic appearance that predicts significant endoleak leading to AAA expansion. These endoleaks are difficult to detect by computed tomography (CT), and CDU and may represent the phenomenon known as endotension when endoleak is not identified. Methods All patients with several EVAR devices were prospectively followed with CDU for evaluation of endoleak at intervals during a 4-year period. All CDU exams were performed using Philips 5000, 3000, and IU22 systems according to protocol. Assessment of the AAA sac with spectral and color Doppler was used to identify endoleak. The B-mode echogenicity of the AAA sac was characterized for echogenicity and sac symmetry. The patients were followed with CT scan and/or angiography for confirmation of endoleaks. Results There were 12 patients with subtle Type II endoleaks and a characteristic texture by CDU identified from 1 month to 16 months after intervention. The endoleaks had low velocities within the sac ranging from 10 to 50 cm/sec with a bidirectional spectral Doppler waveform. An asymmetrical AAA sac with a “spongy” multiechogenic texture was a finding in all 12 patients. The endoleaks were difficult to detect by both CDU and CT scan because of the low velocities despite AAA sac enlargement in all patients. The average AAA sac enlargement was 4.4 mm. CT scan and/or angiography failed to detect endoleak in 6 of 12 patients positive by CDU for endoleak with AAA sac expansion. Conclusion CDU after EVAR can effectively detect the presence of endoleak and assess the B-mode characteristics of the AAA sac. Important clues such as low flow, sac expansion, sac asymmetry, and a “spongy” B-mode appearance are consistent with subtle endoleak that may lead to AAA expansion. When undetected, this type of endoleak may be misdiagnosed as endotension.

Thoracic aortic emergencies: impact of endovascular surgery

Background Conventional surgery for thoracic aortic emergencies, such as contained or free rupture of thoracic aortic aneurysms, acute type B dissections, and traumatic rupture of the thoracic aorta, is frequently associated with a high rate of mortality and morbidity. To obviate this risk, endovascular surgery is considered to be a valid alternative procedure. Methods From March 2001 to July 2002, 15 of 22 patients with acute thoracic aortic syndromes were submitted to endovascular surgery: 3 patients (20%) for traumatic rupture, 4 patients (26.7%) for contained or free rupture of thoracic aortic aneurysm, and 8 patients (53.3%) for acute type B dissection evolving to rupture. Computed tomographic scan was diagnostic in all patients. The stent grafts were introduced through the femoral artery. Results In the endovascular group there were no perioperative deaths or open conversions. The intraoperative angiography and computed tomographic scan performed on discharge showed no significant endoleaks and successful sealing of the aortic dissection. Average intensive care unit and hospital stay was 1.7 ± 0.8 and 5.9 ± 3.0 days. Follow-up ranged between 4 and 23 months and included clinical examinations and serial computed tomographic scan at 3, 6, and 12 months, and every 6 months thereafter. One 84-year-old patient with thoracic aortic aneurysm died of pneumonia 78 days after endovascular surgery. Only one type 1 endoleak was noted in the first patient with traumatic rupture, 3 months after the procedure. Conclusions Endovascular surgery is a safe technique, showing encouraging early and midterm results and allowing for prompt treatment of associated lesions in complex multitrauma patients.