Exercise Pulmonary Hypertension in Asymptomatic Severe Aortic Stenosis.

Conference (2011)

Prediction of exercise pulmonary hypertension in asymptomatic degenerative mitral regurgitation

in Journal of the American Society of Echocardiography (2011), 24(9), 1004-1012

Stress testing in valvular heart disease: Clinical benefit of echocardiographic imaging

in Expert Review of Cardiovascular Therapy (2011), 9(1), 81-92

A simplified model for mitral valve dynamics.

in Computer Methods & Programs in Biomedicine (2011)

Located between the left atrium and the left ventricle, the mitral valve controls flow between these two cardiac chambers. Mitral valve dysfunction is a major cause of cardiac dysfunction and its dynamics ... [more ▼]

Located between the left atrium and the left ventricle, the mitral valve controls flow between these two cardiac chambers. Mitral valve dysfunction is a major cause of cardiac dysfunction and its dynamics are little known. A simple non-linear rotational spring model is developed and implemented to capture the dynamics of the mitral valve. A measured pressure difference curve was used as the input into the model, which represents an applied torque to the anatomical valve chords. A range of mechanical model hysteresis states were investigated to find a model that best matches reported animal data of chord movement during a heartbeat. The study is limited by the use of one dataset found in the literature due to the highly invasive nature of getting this data. However, results clearly highlight fundamental physiological issues, such as the damping and chord stiffness changing within one cardiac cycle, that would be directly represented in any mitral valve model and affect behaviour in dysfunction. Very good correlation was achieved between modeled and experimental valve angle with 1-10% absolute error in the best case, indicating good promise for future simulation of cardiac valvular dysfunction, such as mitral regurgitation or stenosis. In particular, the model provides a pathway to capturing these dysfunctions in terms of modeled stiffness or elastance that can be directly related to anatomical, structural defects and dysfunction. [less ▲]

Influence of thermoelectric coupling on ectopic beats generated by mechano-electric feedback (MEF) in a one-dimensional cardiac fiber model

Poster (2010, November 26)

The influence of thermal processes on electrophysiology has clearly been underlined by Bini et al., using a FitzHugh--Nagumo-type (FHN-type) model. When the temperature is raised, the action potential ... [more ▼]

The influence of thermal processes on electrophysiology has clearly been underlined by Bini et al., using a FitzHugh--Nagumo-type (FHN-type) model. When the temperature is raised, the action potential duration (APD) has been shown to shorten, while the action potential (AP) amplitude decreases, and the conduction velocity increases. In this research, we investigate the effects of thermoelectric coupling on mechano-electric feedback (MEF), and more specifically, on ectopic beats generated by MEF. To investigate these effects, thermoelectric coupling is introduced in a one-dimensional electromechanical model of a cardiac fiber, which considers excitation-contraction coupling (ECC), as well as MEF. [less ▲]

Risk stratification in asymptomatic moderate to severe aortic stenosis: the importance of the valvular, arterial and ventricular interplay.

in Heart (2010), 96(17), 1364-71

OBJECTIVE: We sought to evaluate prognostic markers of clinical outcome in asymptomatic patients with moderate to severe aortic stenosis (AS). DESIGN: Prospective follow-up of asymptomatic patients with ... [more ▼]

OBJECTIVE: We sought to evaluate prognostic markers of clinical outcome in asymptomatic patients with moderate to severe aortic stenosis (AS). DESIGN: Prospective follow-up of asymptomatic patients with moderate to severe AS. The patients underwent clinical and Doppler echocardiographic evaluation. SETTING: Department of Cardiology. PATIENTS: 163 patients with moderate to severe AS (aortic valve area < or =0.6 cm(2)/m(2)). MAIN OUTCOME MEASURES: Risk stratification. Predefined endpoints for assessing the outcome were the occurrence during follow-up of symptoms, aortic valve replacement or death. RESULTS: During follow-up (mean, 20 (19) months), 11 patients developed symptoms but were not operated on, 57 required aortic valve replacement and six patients died. In multivariable Cox regression analysis, four parameters that were associated with the outcome were identified: peak aortic jet velocity, left ventricular systolic (LV) longitudinal deformation, valvulo-arterial impedance and indexed left atrial area. Using receiver-operator characteristic curve analysis, a peak aortic jet velocity > or =4.4 m/s, a LV longitudinal myocardial deformation < or =15.9%, a valvular-arterial impedance > or =4.9 mm Hg/ml per m(2) and an indexed left atrial area > or =12.2 cm(2)/m(2) were identified as the best cut-off values to be associated with events. CONCLUSIONS: In asymptomatic patients with moderate to severe AS, measurements that integrate the ventricular, vascular and valvular components of the disease improve risk stratification. [less ▲]

Etude échocardiographique longitudinale chez des patients atteints de prolactinome et traités par Cabergoline

in 27ème Congrès de la Société Française d'Endocrinologie - Deauville, 29 septembre - 2 octobre 2010 (2010, September)

Exercise pulmonary hypertension in asymptomatic degenerative mitral regurgitation

in Circulation (2010), 122(1), 33-41

BACKGROUND: Current guidelines recommend mitral valve surgery for asymptomatic patients with severe degenerative mitral regurgitation and preserved left ventricular systolic function when exercise ... [more ▼]

BACKGROUND: Current guidelines recommend mitral valve surgery for asymptomatic patients with severe degenerative mitral regurgitation and preserved left ventricular systolic function when exercise pulmonary hypertension (PHT) is present. However, the determinants of exercise PHT have not been evaluated. The aim of this study was to identify the echocardiographic predictors of exercise PHT and the impact on symptoms. <br /> <br />METHODS AND RESULTS: Comprehensive resting and exercise transthoracic echocardiography was performed in 78 consecutive patients (age, 61+/-13 years; 56% men) with at least moderate degenerative mitral regurgitation (effective regurgitant orifice area =43+/-20 mm(2); regurgitant volume =71+/-27 mL). Exercise PHT was defined as a systolic pulmonary arterial pressure (SPAP) >60 mm Hg. Exercise PHT was present in 46% patients. In multivariable analysis, exercise effective regurgitant orifice was an independent determinant of exercise SPAP (P<0.0001) and exercise PHT (P=0.002). Resting PHT and exercise PHT were associated with markedly reduced 2-year symptom-free survival (36+/-14% versus 59+/-7%, P=0.04; 35+/-8% versus 75+/-7%, P<0.0001). After adjustment, although the impact of resting PHT was no longer significant, exercise PHT was identified as an independent predictor of the occurrence of symptoms (hazard ratio=3.4; P=0.002). Receiver-operating characteristics curves revealed that exercise PHT (SPAP >56 mm Hg) was more accurate than resting PHT (SPAP >36 mm Hg) in predicting the occurrence of symptoms during follow-up (P=0.032). <br /> <br />CONCLUSIONS: Exercise PHT is frequent in patients with asymptomatic degenerative mitral regurgitation. Exercise mitral regurgitation severity is a strong independent predictor of both exercise SPAP and exercise PHT. Exercise PHT is associated with markedly low 2-year symptom-free survival, emphasizing the use of exercise echocardiography. An exercise SPAP >56 mm Hg accurately predicts the occurrence of symptoms. [less ▲]

A moving heart

in European Heart Journal (2010)

Exercise echocardiography in severe asymptomatic aortic stenosis.

in Archives of Cardiovascular Diseases (2010), 103(4), 262-269

The management of asymptomatic patients with severe aortic stenosis is challenging. Unfortunately, evaluation of symptoms such as dyspnoea remains subjective. The use of exercise echocardiography may help ... [more ▼]

The management of asymptomatic patients with severe aortic stenosis is challenging. Unfortunately, evaluation of symptoms such as dyspnoea remains subjective. The use of exercise echocardiography may help to predict major events in patients with asymptomatic severe aortic stenosis. This article explains how to perform the test and discusses which echocardiographic measurements should be obtained, focusing on the diagnostic and prognostic value of these measurements. An increase in mean transaortic pressure gradient >or= 18 mmHg predicts a worse prognosis in patients with severe aortic stenosis. The absence of left ventricular contractile reserve also has an important prognostic impact. Evaluation of filling pressures and looking for a worsening or a new mitral regurgitation are also part of the exam. Further studies are required to determine whether surgery should be recommended in the presence of an abnormal exercise echocardiogram in severe asymptomatic aortic stenosis. [less ▲]