Daniel Devos

Carotid to femoral pulse wave velocity: a comparison of real travelled aortic path lengths determined by MRI and superficial measurements.

Objectives Carotid–femoral pulse wave velocity (PWV) is the gold standard method for determination of arterial stiffness. PWV is assessed by dividing travelled distance by travel time. Standardization and validation of the methodology for travelled distance measurement is of crucial importance. The aim of the current investigation was to standardize and validate the methodology for travelled distance measurement. Methods Real travelled carotid–femoral path lengths were measured with MRI in 98 healthy men/women (50% men, age 21–76 years) and are used as reference distance. This reference distance was compared with 11 estimates of aortic path length from body surface distances commonly used in PWV measurement, nine of them based on tape measures and two based on body height. Determinants of the difference between reference distance and the best body surface distance were determined. Additionally, the influence of body contours was identified. Results The tape measure distance from carotid to femoral artery (CA-FA), multiplied by 0.8, yielded the best agreement with the reference aortic path length [difference 0.26 cm (SD 3.8), not statistically significant]. Thirty percent of the variation in difference between the reference distance and tape measure distance (CA-FA × 0.8) was explained by age. Adding BMI increased this number to 34%. Conclusion The tape measure distance from CA-FA, multiplied by 0.8, corresponds best with the real travelled aortic path length. This distance is moderately (yet statistically significantly) influenced by age and minimally by BMI.

The Ghent Marfan Trial — A randomized, double-blind placebo controlled trial with losartan in Marfan patients treated with β-blockers

BACKGROUND Aortic root dilation, dissection and rupture are major clinical problems in Marfan syndrome (MFS). Although β-blockers remain the standard of preventive treatment, preliminary results from animal studies and a selected group of severely affected MFS children show significant benefit from treatment with losartan, an angiotensin II receptor blocker with TGF-β inhibiting potential. Large-scale human trials are now needed to confirm these results. This trial aims to evaluate the combined effect of both drugs. METHODS We are conducting a prospective randomized placebo controlled double blind phase III study aiming to include 174 MFS patients (age ≥ 10 years and z-score ≥ 2). Patients already taking β-blockers are randomized for weight-adjusted treatment with losartan versus placebo. The primary endpoint is decrease in aortic root growth rate. Secondary endpoints are aortic dissection/surgery, progression of aortic/mitral regurgitation, arterial stiffness, left ventricular systolic/diastolic function, quality of life and genetic modifiers. Echocardiography, vascular echo-Doppler and quality of life assessment will be performed at baseline and at 6-monthly follow-ups for 3 years. MRI evaluation will be performed at baseline and at the end of the trial. CONCLUSION This trial will study new therapeutic strategies for the prevention of serious cardiovascular complications in MFS. The uniqueness in our trial is that the additive effect of losartan and β-blocker will be evaluated in a large spectrum of disease severity. A combination of ultrasound and MRI will allow detailed evaluation of anatomic and functional properties of the aorta and left ventricle.

A critical analysis of minor cardiovascular criteria in the diagnostic evaluation of patients with Marfan syndrome

Purpose: The prevalence of most minor cardiovascular manifestations in Marfan syndrome (MFS) is unknown. We assessed the prevalence of minor cardiovascular manifestations in MFS to evaluate their usefulness in a diagnostic setting.Methods: Seventy-seven patients with MFS (aged 4 months to 55 years) underwent echocardiography to assess the presence of mitral valve prolapse and the diameter of the main pulmonary artery. A subset of 29 adult patients with MFS also underwent magnetic resonance imaging evaluation of the diameters of the thoracoabdominal aorta.Results: Mitral valve prolapse was encountered in 66% of patients with MFS, with an equal distribution of classic and nonclassic mitral valve prolapse. The main pulmonary artery diameter was significantly larger in patients with MFS at all ages when compared with controls. In the adult group (≥14 years), we were able to provide a cutoff value of 23 mm to define pulmonary artery dilatation. The descending aorta was enlarged, but with substantial overlap with controls, thus precluding the use of a cutoff value.Conclusions: Mitral valve prolapse and main pulmonary artery dilatation are common findings in MFS patients at all ages and are easy to assess with echocardiography. Cutoff values to define dilatation of the descending aorta are hard to define, making them of limited value in the diagnostic evaluation. We recommend echocardiographic evaluation of mitral valve proplase and main pulmonary artery diameter in patients referred for cardiovascular diagnostic assessment for MFS.

Virtual evaluation of stent graft deployment: a validated modeling and simulation study.

The presented study details the virtual deployment of a bifurcated stent graft (Medtronic Talent) in an Abdominal Aortic Aneurysm model, using the finite element method. The entire deployment procedure is modeled, with the stent graft being crimped and bent according to the vessel geometry, and subsequently released. The finite element results are validated in vitro with placement of the device in a silicone mock aneurysm, using high resolution CT scans to evaluate the result. The presented work confirms the capability of finite element computer simulations to predict the deformed configuration after endovascular aneurysm repair (EVAR). These simulations can be used to quantify mechanical parameters, such as neck dilations, radial forces and stresses in the device, that are difficult or impossible to obtain from medical imaging.

Calculations of cardiovascular shunts and regurgitation using magnetic resonance ventricular volume and aortic and pulmonary flow measurements

Background: Cardiovascular magnetic resonance measurements of the volumes of the right and left ventricle and of the flows in the ascending aorta and main pulmonary artery contribute to the assessment of patients with valvular regurgitation or intracardiac or extracardiac shunts. Ventricular volumes are measured by planimetry and summation of end-diastolic and end-systolic areas measured in a stack of ventricular short-axis cines. The volumes of blood flowing through planes transecting the great arteries are measured using phase contrast velocity mapping. The two approaches are essentially different and can be used either for mutual validation, or separately or in combination to quantify regurgitation and/or shunting. In the presence of shunts, the relations between the stroke volumes and arterial flows of each side of the heart vary depending on the level of shunting (for example, atrial, ventricular or ductal). Conclusion: This article aims to explain and illustrate the technical and theoretical basis for calculations using volumetric and flow measurements, providing formulae and diagrams to facilitate the interpretation of results.

Noninvasive assessment of carotid-femoral pulse wave velocity: the influence of body side and body contours

Background: Recently, an expert group advised to measure carotid-femoral (cf) pulse wave velocity (PWV) on the right side of the body, and to use a sliding caliper when tape measure distance cannot be obtained in a straight line. The present study investigates the evidence for this advice by comparing the real travelled cf path lengths (RTPLs) at both body sides and comparing the straight distance (as can be obtained with a sliding caliper) with the tape measure distance. Methods: RTPLs were measured with MRI in 98 individuals (49 men, age 21–76 years). Path lengths from the aortic arch to the carotid (AA-CA) and femoral (AA-FA) sites were determined. RTPL was calculated as (AA-FA) - (AA-CA) and compared between both sides. RTPLs were compared with 80% of the direct cf distance using a tape measure and the straight cf distance obtained from MRI images. Results: RTPL was slightly longer [11 mm (12), P < 0.001] at the right side. The 80%-rule overestimated RTPLs with 0.5% at the right and 2.7% at the left side. Straight MRI distance tended (P = 0.09) to perform slightly better than tape measure distance. Conclusion: The travelled cf path is slightly longer at the right than at the left body side and the straight MRI distance tends to perform better than tape measure distance. The present study supports the advice of the expert consensus group to measure cf-PWV at the right body side using a sliding caliper when tape measure distance cannot be obtained in a straight line.

Acute and chronic effects of dysfunction of right ventricular outflow tract components on right ventricular performance in a porcine model: implications for primary repair of tetralogy of fallot

OBJECTIVES This study investigates the contribution of infundibular versus pulmonary valve (PV) dysfunction on right ventricular (RV) function in a porcine model. BACKGROUND Clinical outcome after repair of tetralogy of Fallot is determined by the adaptation of the right ventricle to the physiological sequelae of the right ventricular outflow tract (RVOT) reconstruction. Recent surgical techniques are pursuing a PV-versus infundibulum-sparing approach. METHODS In a porcine model, 3 types of RVOT dysfunction were created and compared with sham-operated controls: infundibular dysfunction (INF), PV insufficiency (PI), and combined infundibular-PV dysfunction (TAP). Both acute and chronic effects on RV function were studied by using conductance technology and magnetic resonance imaging. RESULTS In animals with PI, pulmonary regurgitant fraction progressed more in the presence of concomitant INF (54% in TAP versus 14% in PI; p = 0.03). Subsequently, RV end-systolic and end-diastolic volume increased more in both groups, resulting in decreased ejection fraction after 3 months. Preload-independent systolic indices showed acute impairment of RV contractility in all treatment groups but most in animals with infundibular scarring (INF and TAP). Further chronic deterioration was observed in animals of the TAP group. RV compliance improved proportionally most in the PI and TAP groups in relation to the extent of RV dilation. CONCLUSIONS Surgical RVOT dysfunction, whether it includes the infundibulum and/or the PV, has an immediate effect on RV performance. Although impaired RV contractility is due to intrinsic myocardial damage by infundibular distortion, it is chronically furthered by PI-related RV dilation. These findings support the adoption of a RVOT-sparing strategy to treat tetralogy of Fallot.

Validation of the murine aortic arch as a model to study human vascular diseases

Although the murine thoracic aorta and its main branches are widely studied to gain more insight into the pathogenesis of human vascular diseases, detailed anatomical data on the murine aorta are sparse. Moreover, comparative studies between mice and men focusing on the topography and geometry of the heart and aorta are lacking. As this hampers the validation of murine vascular models, the branching pattern of the murine thoracic aorta was examined in 30 vascular corrosion casts. On six casts the intrathoracic position of the heart was compared with that of six younger and six older men of whom contrast‐enhanced computer tomography images of the thorax were three‐dimensionally reconstructed. In addition, the geometry of the human thoracic aorta was compared with that of the mouse by reconstructing micro‐computer tomography images of six murine casts. It was found that the right brachiocephalic trunk, left common carotid artery and left subclavian artery branched subsequently from the aortic arch in both mice and men. The geometry of the branches of the murine aortic arch was quite similar to that of men. In both species the initial segment of the aorta, comprising the ascending aorta, aortic arch and cranial/superior part of the descending aorta, was sigmoidally curved on a cranial/superior view. Although some analogy between the intrathoracic position of the murine and human heart was observed, the murine heart manifestly deviated more ventrally. The major conclusion of this study is that, in both mice and men, the ascending and descending aorta do not lie in a single vertical plane (non‐planar aortic geometry). This contrasts clearly with most domestic mammals in which a planar aortic pattern is present. As the vascular branching pattern of the aortic arch is also similar in mice and men, the murine model seems valuable to study human vascular diseases.

Cardiovascular pathology in males and females with 45,X/46,XY mosaicism

Context The phenotype of 45,X/46,XY mosaicism is heterogeneous ranging from females with Turner syndrome (TS) to apparently normal males. Males with 45,X/46,XY frequently show stigmata typically associated with TS. We hypothesised that males with 45,X/46,XY have similar cardiovascular pathology as females with 45,X/46,XY. Objective To investigate cardiovascular abnormalities in 45,X/46,XY males and to compare them with 45,X/46,XY females. Design Patients with 45,X/46,XY mosaicism were selected from the Belgian Registry for Growth and Puberty problems and via the multidisciplinary clinic for disorders of sexual development. Patients Eighteen patients were included: 8 raised as females (F) and 10 as males (M). Intervention Complete cardiac examination with blood pressure measurement, ECG, echocardiography and MRI. Main Outcome Measurement Cardiac parameters were registered for both groups. In a second phase, clinical features and external masculinisation score (EMS) were retrospectively collected from the medical files. Results A structural heart defect was diagnosed before inclusion in 1 F with coarctation and 1 M with spontaneously closed VSD. A bicuspid aortic valve was found in 8 (3 F, 5 M). Dilation of the ascending aorta was present in 4 M and was severe in 2 young boys. QTc was prolonged in 3 F and 2 M. Conclusion Males with 45,X/46,XY mosaicism have similar cardiovascular pathology as 45,X/46,XY females. Dilation of the ascending aorta can be important, also in males. We advise cardiac screening and life-long monitoring in all males with 45,X/46,XY mosaicism according to the existing guidelines for Turner syndrome.

Functional analysis of the anatomical right ventricular components: should assessment of right ventricular function after repair of tetralogy of Fallot be refined?

OBJECTIVE Follow-up after tetralogy of Fallot (ToF) repair is directed to detect timely right ventricular (RV) dysfunction by following pulmonary regurgitation and global RV size, with little attention for the effective contribution of regional RV dysfunction. This study investigates the contribution of regional RV dysfunction on exercise capacity after ToF repair. METHODS Forty-two patients were investigated with cardiac magnetic resonance imaging for regional RV dysfunction in relation to global RV function by functional quantification of the sinus and outflow part of the RV. The impact of regional and global RV dysfunction on clinical status was studied by exercise testing. RESULTS Global RV function was lower than sinus function (ejection fraction (EF) 52±12% vs 58±10%, P<0.001), attributable to the adverse influence of right ventricular outflow tract (RVOT) dysfunction (EF 34±17%). Percent predicted peak VO2 correlated better with the RV sinus ejection fraction compared with the global RV ejection fraction (r=0.51, P=0.001 vs r=0.44, P=0.004). Multivariate analysis revealed the EF of RV sinus (β=0.34, 95% CI 0.07-0.61, P=0.013) and the extent of RVOT akinesia (β=-0.28, 95% CI -0.50; -0.06, P=0.015) as significant determinants of exercise capacity. Impaired exercise performance occurred in 43% of the patients, and was independently determined by the type of repair (transventricular vs transatrial: OR 6.0, 95% CI 1.31-17.3, P=0.02) by associating greater sinus and RVOT dysfunction. CONCLUSION Functional analysis of the RV components shows that exercise capacity after repair of ToF is better predicted by systolic function of the RV sinus as the extent of RVOT dysfunction commonly leads to underestimation of global RV function. This method of differential quantification of regional RV function might be more appropriate than assessment of global RV function during the long-term follow-up of repaired ToF patients.