Tissue Characterization
Andrea Guala, PhD
Senior Researcher
Hospital Universitari Vall d'Hebron, CIBER-CV
barcelona, Catalonia, Spain
Andrea Guala, PhD
Senior Researcher
Hospital Universitari Vall d'Hebron, CIBER-CV
barcelona, Catalonia, Spain
Myriam Cilla
Researcher
Aragón Institute of Research, University of Zaragoza. CIBER-BBN, Spain
Gisela Teixidó-Turà, MD, PhD
Cardiologist
Hospital Universitari Vall d'Hebron, Spain
MIguel Ángel Martínez, PhD
Researcher
Aragón Institute of Research, University of Zaragoza. CIBER-BBN, Spain
Lydia Dux-Santoy, PhD
Researcher
Hospital Universitari Vall d'Hebron, Catalonia, Spain
Laura Galian-Gay, MD, PhD
Cardiologist
Hospital Universitari Vall d'Hebron
Barcelona, Catalonia, Spain
Juan Garrido-Oliver, MSc
Researcher, engineer
Hospital Universitari Vall d'Hebron, Spain
Aroa Ruiz-Muñoz, MSc
Researcher
Hospital Universitari Vall d'Hebron, Spain
Luz Servato, MD
Cardiologist
Hospital Universitari Vall d'Hebron, Spain
Augusto Sao-Avilés, PhD
Researcher
Hospital Universitari Vall d'Hebron, Spain
Alejandro Carrasco-Poves, MSc
Predoctoral researcher
Hospital Universitari Vall d'Hebron, Spain
Ignacio Ferreira-Gonzáiez, MD, PhD
Cardiologist
Hospital Universitari Vall d'Hebron, Spain
Artur Evangelista, MD, PhD
Cardiologist
Hospital Universitari Vall d'Hebron, Spain
Estefanía Peña, PhD
Researcher
Aragón Institute of Research, University of Zaragoza. CIBER-BBN, Spain
Jose F Rodriguez Palomares, MD, PhD, FSCMR
Cardiologist
Hospital Universitari Vall d'Hebron
Barcelona, Spain
Aortic stiffness predicts future adverse cardiovascular events and mortality in the general population(1).
Several parameters expected to be related to aortic stiffness can be computed from cardiovascular magnetic resonance (CMR) images such as pulse wave velocity (PWV), distensibility (AD) and aortic longitudinal strain, but no validation has been performed. We aimed to validate aortic stiffness descriptors by CMR against ex-vivo mechanical testing of aortic specimens.
Methods:
Ascending aorta (AscAo) specimens were extracted from 20 patients who underwent AscAo aneurysms resection. In the days leading to the surgery all patients underwent a comprehensive CMR protocol, including bSSFP images and a 4D flow CMR of the thoracic aorta. Specimens were extracted keeping record of their original position and orientation, and were frozen until test. For each patient 2 specimens (15x5 mm), one oriented in the circumferential and the other in the longitudinal aortic direction, were tested under control for extension force (I5558, INSTRON). Specimens elongation was quantifies by laser video extensometer (2663-281, INSTRON). The stress-strain curve at diastolic pressure was extracted and the tangent used (2). From 4D flow CMR the AscAo PWV was extracted and the product of Eh (E being Young modulus and h wall thickness) was computed via the Moens-Korteweg equation and the mean AscAo diameter(3,4). AD was quantified from bSSFP images of the AscAo at the pulmonary artery level using ARTFUN software (INSERM U678, France). AscAo longitudinal strain was computed by tracking the position of the aortic root all over the cardiac cycle (5).
Results:
Patients mean age was 52.5 [37.3 – 71.0] years, 13 were male, BSA was 1.94 [1.74 – 1.94] m2 and systolic and diastolic blood pressure were 138 [111 - 145] and 74 [68 - 81] mmHg, respectively. Six patients had Marfan syndrome, 3 Loeys-Dietz syndrome, and 2 a bicuspid aortic valve while the remaining patients had AscAo aneurysms of degenerative origin. Failures included a circumferential specimen extracted that could not be tested, one AD could not be quantified due to the absence of blood pressure values and PWV could not be measured in 2 patients due to 4D flow study failure.
Marked correlations were demonstrated between circumferential elastic modulus at diastolic blood pressure and AscAo PWV (R = 0.652), Eh (R = 0.602) and AD (R = -0.502) (Figure 1 A, B and C, respectively). Similarly, good correlation was identified between AscAo longitudinal strain and longitudinal elastic modulus at diastolic blood pressure (R = -0.513) (Figure 1D).
Conclusion:
Pulse wave velocity and the derived Eh product are positively related to aortic wall stiffness while aortic distensibility and strain show negatively related to local wall stiffness. CMR-derived biomarkers allow for a non-invasive, reliable quantification of aortic wall stiffness.