January 7, 2006
View Full PaperAortic reflection coefficients and their association with global indexes of wave reflection in healthy controls and patients with Marfan's syndrome
Key Result
Global wave reflection indexes were not higher in patients with Marfan's syndrome compared to controls, although aortic pulse wave velocity was 42 cm/s higher (P<0.05).
Study Design
Type
Case-Control (n=52)
Structured PICO
Are aortic reflection coefficients and global indexes of wave reflection elevated in patients with Marfan's syndrome compared to healthy controls?
P
Population
26 patients with Marfan's syndrome (13-54 years of age) and 26 age- and gender-matched healthy controls.
I
Intervention
Measurement of central pressure and flow waveforms using ultrasound and MRI.
C
Comparator
Age- and gender-matched healthy controls.
O
Outcome
Aortic reflection coefficients (local characteristic impedance and local reflection coefficients) and global wave reflection indexes (augmentation index and ratio of backward to forward pressure wave).surrogate
Global wave reflection indexes and local reflection coefficients are not significantly elevated in patients with Marfan's syndrome compared to healthy controls, despite higher aortic pulse wave velocity.
Abstract
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 (Gamma(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, Gamma(AA-DA) was 0.31 +/- 0.08, Gamma(DA-DIA) was 0.00 +/- 0.11, and Gamma(DIA-AB) was 0.31 +/- 0.16. Mean values of Gamma(xx-yy) were not different between MFS patients and controls. In controls, aging diminished Gamma(AA-DA) but increased Gamma(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).