Aortic reflection coefficients and their association with global indexes of wave reflection in healthy controls and patients with Marfan's syndrome

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 290; no. 6; pp. H2385 - H2392
• Main Authors: Segers, P, De Backer, J, Devos, D, Rabben, S. I, Gillebert, T. C, Van Bortel, L. M, De Sutter, J, De Paepe, A, Verdonck, P. R
• Format: Journal Article
• Language: English
• Published: United States 01.06.2006
• Subjects: Adolescent; Adult; Aging - physiology; Algorithms; Aorta - diagnostic imaging; Aorta - pathology; Aorta, Thoracic - diagnostic imaging; Aorta, Thoracic - pathology; Body Height - physiology; Body Surface Area; Body Weight - physiology; Female; Humans; Linear Models; Magnetic Resonance Imaging; Male; Marfan Syndrome - diagnostic imaging; Marfan Syndrome - pathology; Middle Aged; Regional Blood Flow - physiology; Ultrasonography; Vascular Resistance - physiology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01207.2005

1 Cardiovascular Mechanics and Biofluid Dynamics, Institute of Biomedical Technology, Ghent University; Departments of 2 Medical Genetics, 3 Cardiovascular Medicine, and 4 Medical Imaging, and 6 Heymans Institute of Pharmacology, Ghent University Hospital, Ghent, Belgium; and 5 Institute for Surgical Research, Rikshospitalet University Hospital, Oslo, Norway Submitted 15 November 2005 ; accepted in final form 2 January 2006 Early return of reflected pressure waves increases the load on central arteries and may increase the risk of aortic rupture in patients with Marfan's syndrome (MFS). To assess whether wave reflection is elevated in MFS, we used ultrasound and MRI to measure central pressure and flow waveforms in 26 patients (13–54 yr of age) and 26 age- and gender-matched controls. Aortic systolic and diastolic cross-sectional areas were measured at the ascending and descending aorta (AA and DA), diaphragm (DIA), and lower abdominal aorta (AB). From these measurements, local characteristic impedance ( Z 0- xx ) and local reflection coefficients ( xx-yy ) were calculated. Calculated global wave reflection indexes were the augmentation index (AIx) and the ratio of backward to forward pressure wave (P b /P f ). The aorta was wider in MFS patients at AA ( P < 0.01) and DA ( P < 0.01). Aortic pulse wave velocity was 42 cm/s higher in MFS patients ( P < 0.05). Z 0- xx was not different between groups, except at DA, where it was lower in MFS patients. In controls, AA-DA was 0.31 ± 0.08, DA-DIA was 0.00 ± 0.11, and DIA-AB was 0.31 ± 0.16. Mean values of xx-yy were not different between MFS patients and controls. In controls, aging diminished AA-DA but increased DIA-AB . Clear age-related patterns were absent in MFS patients. AIx or P b /P f was not higher in MFS patients than in controls. There were indications for enhanced wave reflection in young MFS patients. Our data demonstrated that the major determinants of AIx were pulse wave velocity and the effective length of the arterial system and, to a lesser degree, HR and P b /P f . magnetic resonance imaging; augmentation index Address for reprint requests and other correspondence: P. Segers, Cardiovascular Mechanics and Biofluid Dynamics, Hydraulics Laboratory, Institute Biomedical Technology, Ghent Univ., Sint-Pietersnieuwstraat 41, 9000 Ghent, Belgium (e-mail: patrick.segers{at}ugent.be )