P262. Predictors of Ascending Aortic Biomechanics Using Epiaortic Ultrasound: The Role of Aortopathy
Cleveland Clinic
Cleveland, OH
United States - Contact Me
Abigail Snyder is a fourth-year medical student and aspiring cardiothoracic surgeon studying at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, a 5-year medical degree program with a strong emphasis on academic research. Her interest in cardiothoracic surgery began in her gap year before medical school at the University of Maryland when she completed clinical research in intracardiac stem cell injection therapy for pediatric patients with hypoplastic left heart syndrome. Eugene Blackstone, MD and Eric Roselli, MD, are her current mentors guiding her research in aortic biomechanics, aortic dissection, and adult cardiac surgery. She is currently completing her clinical research master’s thesis investigating in vivo aortic mechanical behavior in the setting of ascending aortic aneurysm.
Abigail earned a BSE in bioengineering with a concentration in cellular engineering from the University of Pittsburgh, where her research was centered around the development of novel small diameter tissue-engineered vascular grafts for coronary artery disease. Following completion of her master’s degree this year she plans to apply to cardiothoracic surgery residency. She is grateful for the opportunity to be sharing her work at the AATS Annual Meeting and would like to thank Dr. Roselli and Dr. Blackstone, as well as the entire research team, for their support and mentorship.
Description
Methods: Patients with ascending aortic aneurysm undergoing aortic replacement and patients undergoing coronary artery bypass grafting (CABG) underwent intraoperative transesophageal and ascending epiaortic ultrasound; CABG patients were only enrolled if the maximum ascending aortic diameter was less than 4.0 cm and there was no evidence of aortic value disease on preoperative imaging. In-vivo biomechanical assessment was performed using 2D image speckle tracking of short axis images to evaluate mechanical outcomes (distensibility, GCS, and SI). Unadjusted and multivariable mixed-effects modeling, as well as machine learning gradient boosting models were implemented to characterize the relationships and independent effect of covariates on biomechanical outcomes.
Results: Between 7/2021-11/2023, a total of 369 short-axis images of the ascending aorta were acquired from 95 patients undergoing aneurysm repair. Additionally, 129 images were obtained from 39 patients undergoing CABG. Images were obtained from the aortic root (94 aTAA, 36 CABG), the proximal (91 aTAA, 31 CABG), mid (92 aTAA, 31 CABG), and distal (92 aTAA, 31 CABG) ascending aorta. The aneurysm cohort was younger (55 ± 15 years vs 67±10 years, P<.01), had a greater prevalence of bicuspid aortic valve (53 [56%] vs 0, P<.01), and were less likely to have hypertension (57 [60%] vs 39 [100%], P<.01). When comparing the aneurysm and CABG cohorts, patients with aneurysm demonstrated a higher distensibility (9.1 ± 6.9 mmHg-1 vs 6.2 ± 4.5 mmHg-1, P<.01, Figure 1A), higher GCS (6.4 ± 4.5% vs P<.01), and a lower SI (13.1 ± 9.3 vs 18.1 ± 9.7, P<.01). Multivariable mixed-effects and gradient boosting modeling of the aneurysm cohort demonstrated that distensibility was negatively associated with age (β= -.17, P<.01) and had the largest positive association with the root region (βRoot =8.4, βProx = 1.2, βMid =.2, P<.01, Figure 1B). Similar results were demonstrated for the GCS and SI. In the CABG cohort, region was similarly positively associated with distensibility (βRoot =5.6, βProx =.02, βMid =-.2, P<.01, Figure 1C) and GCS (βRoot =3.3, βProx =.3, βMid =-.3, P<.01). SI was negatively associated with region (βRoot =-11, βProx =-2.4, βMid =.9, P<.01) and ascending aortic length (β =-.1, P=.04) and positively associated with age (β=.2, P=.02). When examining both cohorts together the mixed effect model of distensibility demonstrates a negatively associated interaction term between age and the aortic area at the image location (β =-.006, P=.05), and positive association with the aortic area at the image location (β =.14, P=.04), the ascending aortic length (β =.05, P=.01), and aortic proximity (βRoot =7.5, βProx =.7, βMid =-.04, P<.01).
Conclusions: Across both cohorts, lengthwise regional variation consistently emerges as a significant predictor of in-vivo biomechanics. However, age had a more pronounced effect in the aneurysm cohort. The presence of an ascending aneurysm may exacerbate age related aortic tissue dysfunction. Clinical judgement is necessary to determine the optimal surgical timing balancing age and ascending aortic area.
Authors
Abigail Snyder (1), Benjamin Kramer (2), Matthew Thompson (3), Ashley Lowry (4), Eugene Blackstone (1), Jennifer Hargrave (1), Eric Roselli (1)
Institutions
(1) Cleveland Clinic, Cleveland, OH, (2) Cleveland Clinic, United States, (3) Cleveland Clinic, Lakewood, OH, (4) Cleveland Clinic, Department of Quantitative Health Sciences, Cleveland, OH