2020 IICMS Bursary Recipient – Vascular Faculty – Michelle O’Hare, MPHIL
2020 IICMS Bursary Recipient
Michelle O’Hare, MPHIL 2020
Title: Colour Duplex Ultrasound as the Sole Imaging Modality Immediately Post-Operative Endovascular Aneurysm Repair
Background and purpose: An abdominal aortic aneurysm (AAA) is a common and potentially life-threatening condition with the risk of rupture increasing in accordance with increasing aneurysm sac size. Endovascular Aortic Aneurysm Repair (EVAR) has evolved into a viable alternative to open surgery repair with Computed Tomography Angiography (CTA) being considered the gold standard technique for surveillance following EVARs. However, CTA has the disadvantages of cost, risk of contrast nephropathy and radiation exposure. Colour Duplex ultrasound (CDU) is widely used as a screening and surveillance tool for AAA and is also effective in the detection of endoleaks in addition to changes in sac diameters during EVAR surveillance. It has been previously proven that CDU is a safer alternative than CTA for long term EVAR surveillance. The aim of this study is to compare immediate post-operative EVAR CDU and CTA results and assess whether post-operative CTA is required if satisfactory post-operative CDU thus changing the current surveillance algorithm.
Methods: All patients who underwent EVAR between the 1st of January 2007 to the 31st of December 2017 for their Abdominal Aortic Aneurysms in Mater Misericordiae university hospital (MMUH) were retrospectively reviewed. Patient demographics including date of surgery, the immediate post-operative CTA and CDU result, the date when each was performed, the maximum residual aneurysm sac diameter and the presence and type of endoleak on both imaging modalities were obtained and entered onto an EXCEL spreadsheet for analysis. Patients who did not have either a CTA or CDU within 7 days post-operative of their treatment were excluded from the study. The patient’s immediate post-operative CDU and CTA results were compared for residual aneurysm measurement, detection of an endoleak and classification of endoleak using CTA as the gold standard.
Results: Of the 251 patients included in this study, 218 (86.9%) of these were male with a mean age of 70.8 years +/- 12.1 years and 33 (13.1%) were female with a mean age of 74.8 years +/-6.7 years. A p-value of 0.95 and a Pearson Correlation co-efficient, r, of 0.8 was obtained indicating a high degree of correlation between CDU and CTA for the measurement of residual aneurysm sac size immediately post EVAR. A Pearson correlation test was performed for the detection of an endoleak and a value of 0.30 was obtained indicating medium correlation between CTA and CDU. A Pearson’s correlation of 0.30 was obtained for classification for type II endoleaks.
Conclusion: CDU is effective for measuring residual aneurysm sac as well as identifying possible complications such as endoleaks post EVAR. However, this study does not provide sufficient evidence to suggest that removing the post-operative CTA completely would be an acceptable change to the current surveillance algorithm in MMUH.