E. Mousseaux

Reduced Ascending Aortic Strain and Distensibility Earliest Manifestations of Vascular Aging in Humans

Arterial stiffness predicts cardiovascular events beyond traditional risk factors. However, the relationship with aging of novel noninvasive measures of aortic function by MRI and their interrelationship with established markers of vascular stiffness remain unclear and currently limit their potential impact. Our aim was to compare age-related changes of central measures of aortic function with carotid distensibility, global carotid–femoral pulse wave velocity, and wave reflections. We determined aortic strain, distensibility, and aortic arch pulse wave velocity by MRI, carotid distensibility by ultrasound, and carotid–femoral pulse wave velocity by tonometry in 111 asymptomatic subjects (54 men, age range: 20 to 84 years). Central pressures were used to calculate aortic distensibility. Peripheral and central pulse pressure, augmentation index, and carotid–femoral pulse wave velocity increased with age, but aortic strain and aortic arch PWV were most closely and specifically related to aging. Ascending aortic (AA) strain and distensibility decreased, respectively, by 5.3±0.5% (R2=0.54, P<0.0001) and 13.6±1 kPa−1×10−3 (R2=0.62, P<0.0001), and aortic arch pulse wave velocity increased by 1.6±0.13 m/sec (R2=0.60, P<0.0001) for each decade of age after adjustment for gender, body size, and heart rate. We demonstrate in this study a dramatic decrease in AA distensibility before the fifth decade of life in individuals with diverse prevalence of risk factors free of overt cardiovascular disease. In particular, compared with other measures of aortic function, the best markers of subclinical large artery stiffening, were AA distensibility in younger and aortic arch pulse wave velocity in older individuals.

Age-Related Changes in Aortic Arch Geometry: Relationship With Proximal Aortic Function and Left Ventricular Mass and Remodeling

OBJECTIVES We sought to define age-related geometric changes of the aortic arch and determine their relationship to central aortic stiffness and left ventricular (LV) remodeling. BACKGROUND The proximal aorta has been shown to thicken, enlarge in diameter, and lengthen with aging in humans. However, no systematic study has described age-related longitudinal and transversal remodeling of the aortic arch and their relationship with LV mass and remodeling. METHODS We studied 100 subjects (55 women, 45 men, average age 46 ± 16 years) free of overt cardiovascular disease using magnetic resonance imaging to determine aortic arch geometry (length, diameters, height, width, and curvature), aortic arch function (local aortic distensibility and arch pulse wave velocity [PWV]), and LV volumes and mass. Radial tonometry was used to calculate central blood pressure. RESULTS Aortic diameters and arch length increased significantly with age. The ascending aorta length increased most, with age leading to aortic arch widening and decreased curvature. These geometric changes of the aortic arch were significantly related to decreased ascending aortic distensibility, increased aortic arch PWV (p < 0.001), and increased central blood pressures (p < 0.001). Increased ascending aortic diameter, lengthening, and decreased curvature of the aortic arch (unfolding) were all significantly associated with increased LV mass and concentric remodeling independently of age, sex, body size, and central blood pressure (p < 0.01). CONCLUSIONS Age-related unfolding of the aortic arch is related to increased proximal aortic stiffness in individuals without cardiovascular disease and associated with increased LV mass and mass-to-volume ratio independent of age, body size, central pressure, and cardiovascular risk factors.

Regularized reconstruction of 3D high-resolution magnetic resonance images from acquisitions of anisotropically degraded resolutions

We present an original method to reconstruct 3D magnetic resonance images of high resolution in the 3 directions of space from two anisotropic volumes. The resolution of each volume is degraded in a different direction. The reconstruction method is based on an optimization technique, the constraints being fidelity to the acquired data on the one hand, smoothness and edge preservation on the other hand. The interest of such a method is to significantly decrease the acquisition time of MR images, without degrading the spatial resolution.

1070 Adverse systemic right ventricular remodeling and ventricular interdependence leading to symptoms in atrial switch patients with transposition of the great vessels can be detected by biventricular geometry, function and mass assessment in CMR

Background Symptoms of heart failure are a late but strong predictor of adverse outcome in atrial switch patients. Long term adaptation of the systemic right ventricle and left ventricle is a complex process with modifications in ventricular volumes, mass, geometry and function, combined with fibrosis. These remodeling parameters need to be further investigated to guide difficult management strategies regarding medical, interventional and resynchronization therapy. In particular, we hypothesized that an adverse remodeling pattern based on geometric and functional parameters of both ventricles in atrial switch patients could be determined by CMR and differentiate symptomatic from asymptomatic patients. The subsequent study was to compare the remodeling parameters in patients to a normal population.

Measuring aortic distensibility with cmr using central pressures estimated in the magnet: comparison with carotid and peripheral pressures

Objective To evaluate the feasibility and consequences on local aortic distensibility estimation of using central pressure measurement in the magnet, simultaneous to aortic imaging with CMR Background Several studies have demonstrated the feasibility and value of studying local aortic strain with CMR. Calculating aortic distensibility ideally requires the knowledge of simultaneously acquired central pressure changes which until recently remained a challenge during CMR. New MR-compatible devices using an oscillometric technique to estimate central pressures from a brachial cuff are now available but poorly evaluated in this setting. Methods We studied 49 subjects (26 men, 23 women, age 44±18 years) free from overt cardiovascular disease. Ascending aortic strain was determined by CMR using an automated segmentation of SSFP cine acquisitions. Central pressures were estimated from 1) carotid pressures measured immediately after the CMR exam using applanation tonometry and 2) brachial cuff pressure measured simultaneously with aortic cine imaging in the magnet, using the Vicorder™ Device . In both cases, mean brachial pressures was integrated in the calculation of central pressures after applying the transfert function. Central pressures were used to calculate the aortic distensibility defined as the ratio between aortic strain and central pulse pressure (AAD-carotid for carotid pressure and AAD-vicorder for the Vicorder device pressure) and applanation tonometry was further used to estimate the carotid augmentation index (AIx) and Carotid-femoral pulse wave velocity (cfPWV). Results Average±SD systolic brachial, carotid and Vicorder pressures were respectively: 114±13, 105±13, 106±14mmHg. We found a strong linear relationship between AADcarotid and AAD-vicorder (b=0.89, R2=0.91, p<0.001) with however a larger spread between values at higher pressures. The mean distensibility difference between the two methods was: -1.1±12 mmHg-1 and variability 0.9%. Expectedly, distensibility values measured using peripheral brachial cuff pressures were lower than using either central pressures due to the amplification phenomenon in relation to vascular aging (Table). The correlations between local aortic distensibility with age, AIx and cfPWV were significantly higher when using AAD-vicorder (respectively: r=-0.82, r=-0.62; r=0.61; p<0.001) than when using AAD-carotid (r=-0.79, r=-0.50, r=-0.58; p<0.001). Conclusions Aortic distensibility may be measured by CMR using central pressures measured directly in the magnet, simultaneously with cine acquisitions. Resulting distensibilities are closely related to those using carotid pressures measured by tonometry outside the magnet and achieve higher correlation with age and markers of global aortic stiffness such as AIx and cfPWV.

Long-term cocaine use is associated with premature alterations in regional aortic strain and distensibility measured by magnetic resonance imaging

Methods We enrolled 46 consecutive subjects from an addiction clinic: 33 long term cocaine users (13 men, 20 women, mean age: 46 ± 7 yrs, mean years of cocaine use: 15 ± 8) and 13 non-cocaine users (6 men, 7 women, mean age: 43 ± 9 yrs). Aortic stiffness of the ascending and descending aorta was determined by MRI from aortic strain (AS: relative difference in cross-sectional area) and distensibility (AD: aortic strain normalized by pulse pressure) using an automated contours detection method applied to modulus images of a phase-contrast acquisition perpendicular to the ascending aorta (Art-Fun, INSERM). Blood pressure was measured by a brachial cuff during aortic MRI. Drug and smoking habitus was determined by a standardized questionnaire. Results SBP was slightly higher in the cocaine group vs. non-users (130 ± 18 vs. 123 ± 37 mmHg) but pulse pressure was comparable (47 ± 12 vs. 46 ± 10 mmHg respectively) and hypertension was similarly distributed (30% vs. 38%). Total cholesterol was also slightly higher (174 ± 36 vs. 168 ± 35 mg) and current cigarette smoking more prevalent in the cocaine group (88% vs. 30%). Only 3 subjects of the cocaine group were diabetics and no diabetes in nonusers. Aortic strain and distensibility were lower in the cocaine group vs. non-users as summarized in Table 1. Univariate analysis showed a negative correlation between aortic strain and distensibility and duration of cocaine use. After further adjustment for age, gender, cholesterol, smoking and diabetes the duration of cocaine use was an independent predictor of descending aortic function with a significant average decrease in strain of 2.5% (p = 0.02) and a trend for a decrease in distensibility of 4.5 × 10-3.kPa-1 (p = 0.14) for 1 year of cocaine use.

104: Comparison of multidetector row computed tomography to echocardiography for evaluation of patients with mechanical and biological prosthetic valves

Objective Our objective was to evaluate whether ECG gated multidetector-row computed tomographic (MDCT) imaging could detect the abnormalities of prosthetic heart valves. Methods We reviewed the image sequences of 35 patients who underwent a MDCT and a echocardiography (TTE) with a total of 46 prosthetic valves (PV) in different position: 27 bileaflet PV, 2 tilting disc, 2 caged ball PV, and 15 biological PV. According to TTE data, 21 were abnormal and 25 normal. MDCT data were retrospectively reconstructed and analyzed using reformatting in anatomically adapted planes. Results The abnormalities on CT were following: 12 obstructions, 14 dehiscences and 1 vegetation. MDCT identified obstruction with a sensitivity of 100% and specificity of 84%. The causes for obstruction were subprosthetic tissue (pannus) (n=3), thrombus (n=2), leaflets calcifications (n=4), periprostetic and annulus calcifications (n=6). A good correlation was found between the mean prosthetic gradient on TTE and difference of angles for bileaflet PV on MDCT (r=0,7, p=0,0005). 4 patients with PV obstruction were re-operated and the MDCT imaging was confirmed by surgery. MDCT identified dehiscence of PV with a sensitivity of 100% and specificity of 84%. MDCT detect the false aneurysms (n=4) and sequels of ancient abscess (n=6). 5 patients were re-operated and the MDCT imaging of dehiscence was confirmed by surgery. In 6 cases, MDCT showed abnormalities that were not seen during TTE: 3 dehiscences of PV and 3 opening dysfunction of PV without significant obstruction (1 pannus, 1 calcification of prosthetic annulus and 1 asymmetry of opening. The Bjork PV cannot be exanimated on MDCT because of numerous artifacts. Conclusion This experience demonstrates that MDCT have additional value because it can show perivalvular structures as well as cardiac and mediastinal abnormalities and can identify causes of PV dysfunction that constitute indications for surgery, but could be are missed at TTE.