Clinical Considerations in Prosthetic Aortic Graft Replacement
Prosthetic graft replacement in patients with ascending aortic aneurysms is a lifesaving procedure, eliminating the risk for dilatation or dissection in the segments that have been surgically replaced. The well-established interventional therapy is recommended by consensus guidelines put forth a decade ago. (Circulation, 2010 Apr 6;121(13):e266-369)
Our cardiac surgeons have extensive experience in aneurysm surgery and continue to pursue research that enhances the understanding of aortic pathologies and the methods used to treat them. The collaboration of cardiothoracic surgeons, cardiologists, and cardiac imaging specialists continues to advance surgical procedures for ascending aortic aneurysms that enable the preservation of the native valve, facilitate the understanding and management of potential complications, and continue to improve patient outcomes.
In particular, Weill Cornell physicians reinforce that lifetime surveillance imaging of the entire aorta is warranted for patients at particular risk, such as those with congenital or genetically associated aortic aneurysms, and that follow up in experienced aortic centers of excellence is the best way to identify those in need of early intervention.
Modern imaging technology has fostered better understanding of the physics and engineering of the cardiovascular system, enabling cardiac specialists to identify subtle changes in the aorta. This includes not only shape, size, and tissue properties and flow, but also fibrosis in the aortic wall, which may be a driver in increasing size.
Our cardiac surgeons now plan the optimal surgical technique for recreating normal physiology and tailoring procedures to an individual patient’s aortic physiology using four-dimensional flow MRI and computational fluid dynamics. By interpreting the flow dynamics in the aorta, they can determine if they are providing optimal flow to the coronary arteries and minimize stress on flow in the native aorta beyond the aneurysm repair to prevent complications such as new aneurysms, tears, and dissections.
Characterizing the Risks of Prosthetic Aortic Graft Replacement
While ascending aorta replacement can be performed safely in high volume centers, our cardiac faculty continue to expand the knowledge base related to potential risks and complications through ongoing research. In two recent studies, they sought to answer the following questions:
What is the long-term impact on native descending aortic physiology following prosthetic aortic graft replacement?
With the long-term impact on native descending aortic physiology and the potential for complications poorly understood following prosthetic aortic graft replacement, researchers at Weill Cornell sought to clarify the factors that facilitate adverse events in the non-grafted regions. In prior research, the Weill Cornell team had demonstrated via intraoperative transesophageal echocardiography that circumferential deformation and distensibility of the distal native aorta increased significantly acutely after prosthetic replacement of the ascending aorta. This foundational research also provided better understanding of the mechanisms behind ongoing aortic remodeling of the descending aorta after proximal grafting and why the risk is greatest in patients with genetically associated aortopathies.
Results of their recent retrospective review of 46 patients who had undergone surgical prosthetic graft replacement of the aortic aneurysm (AA), including those with congenital or genetically associated AA, revealed the following:
- Prosthetic graft replacement of the ascending aorta increases magnitude and rapidity of distal aortic distension
- Graft effects are greatest with congenital or genetically associated AA, providing a potential mechanism for increased energy transmission to the native descending aorta and adverse postsurgical aortic remodeling
- Heightened risk following prosthetic graft surgery may be due to altered vascular tissue properties of the native aorta
- Grafts may have an impact on aortic physiology as they differ from the native aorta in geometry and distensibility, providing a stiff conduit to propagate high velocity flow into non-grafted segments
The authors conclude that information gleaned from this study suggest that prosthetic graft replacement of the ascending aorta increases magnitude and early timing of distal aortic distension in patients with congenital or genetically associated AA and paves the way for additional studies to further define the role of grafting and/or genetics in postoperative changes.
Does concomitant coronary revascularization with bypass grafting affect postoperative outcomes of ascending aorta replacement?
To better understand the influence of CABG on ascending aorta replacement, Weill Cornell researchers analyzed the cases of 951 patients who underwent ascending aorta replacement between 1997 and 2018 to identify associated major adverse events, including operative mortality, perioperative myocardial infarction, stroke, need for tracheostomy, and need for dialysis. Of the 951 patients, 725 (76.2 percent) underwent isolated ascending aorta replacement (AAR), and 226 (23.8 percent) underwent AAR with CABG. Their findings showed that the performance of concomitant CABG is not associated with an increased risk of major adverse events in patients undergoing concomitant CABG with AAR, and that preoperative pulmonary dysfunction was the only independent predictor of such events.
Rong LQ, Palumbo MC, Rahouma M, Meineri M, Arguelles GR, Kim J, Lau C, Devereux RB, Pryor KO, Girardi LN, Redaelli A, Gaudino MFL, Weinsaft JW. Immediate impact of prosthetic graft replacement of the ascending aorta on circumferential strain in the descending aorta. European Journal of Vascular and Endovascular Surgery. 2019 Oct;58(4):521-528.
Palumbo MC, Rong LQ, Kim J, Navid P, Sultana R, Butcher J, Redaelli A, Roman MJ, Devereux RB,Girardi LN, Gaudino MFL, Weinsaft JW. Prosthetic aortic graft replacement of the ascending thoracic aorta alters biomechanics of the native descending aorta as assessed by transthoracic echocardiography. PLOS ONE. 2020 Mar 12;15(3):e0230208.
Robinson NB, Hameed I, Naik A, Ishtiaq MF, Rahouma M, Girardi LN, Gaudino M. Effect of concomitant coronary artery bypass grafting on outcomes of ascending aorta replacement. The Annals of Thoracic Surgery. 2020 Apr 25:S0003-4975(20)30608-1.