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Métras, Jacques

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Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval
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Voici les éléments 1 - 4 sur 4
  • Publication
    Patient-prothesis mismatch can be predicted at the time of operation
    (Little, Brown & Co., etc., 2001-05-15) Métras, Jacques; Lemieux, Michel; Cartier, Paul C.; Pibarot, Philippe; Dumesnil, Jean G.
    Background. Patient-prosthesis mismatch is a frequent cause of high postoperative gradients in normally functioning prostheses. The objective of this study was to determine whether mismatch can be predicted at the time of operation. Methods. Indices used to predict mismatch were valve size, indexed internal geometric area, and projected indexed effective orifice area (EOA) calculated at the time of operation, and results were compared with indexed EOA and mean gradients measured by Doppler echocardiography after operation in 396 patients. Results. The sensitivity and specificity of these indices to detect mismatch, defined as a postoperative indexed EOA of 0.85 cm2/m2 or less, were respectively: 35% and 84% for valve size, 46% and 85% for indexed internal geometric area, and 73% and 80% for projected indexed EOA. Projected indexed EOA also correlated best with resting (r = 0.67) and exercise (r = 0.77) postoperative gradients. Conclusions. The projected indexed EOA calculated at the time of operation accurately predicts mismatch as well as resting and exercise postoperative gradients, whereas valve size and indexed internal geometric area cannot be used for this purpose.
  • Publication
    Changes in left ventricular mass and function after aortic valve replacement: a comparison between stentless and stented bioprosthetic valves.
    (Mosby, 1999-11-01) Métras, Jacques; Cartier, Paul C.; LeBlanc, Marie-Hélène; Pibarot, Philippe; Dumesnil, Jean G.
    The objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to the postoperative changes in left ventricular (LV) mass and function. Forty patients with aortic stenosis undergoing valve replacement with a stentless (20 patients) or a stented (20 patients) bioprosthesis were evaluated early (baseline), 1 year, and 2 years after operation. Left ventricular mass index was calculated with the corrected American Society of Echocardiography formula. The relative changes between end-diastole and end-systole in LV mid-wall radius, length, and volume (ejection fraction) were determined with a previously validated model for dynamic geometry of the left ventricle. Overall, a significant decrease was found in LV mass index (from 155 ± 30 to 112 ± 23 g/m 2; P < .001) and a significant increase in longitudinal shortening (from 0.12 ± 0.11 to 0.22 ± 0.08; P < .001), and ejection fractions (from 0.67 ± 0.11 to 0.71 ± 0.10; P = .017). No significant change was found in the mid-wall radius shortening fraction. Two years after surgery, the extent of LV mass regression was greater in stentless bioprostheses (–51 ± 18 vs –35 ± 17 g/m 2; P = .01), though the average mass index was similar in both groups (114 ± 26 vs 110 ± 20 g/m 2). Also at 2 years, the longitudinal shortening fraction was greater in patients with a stentless bioprosthesis (0.25 ± 0.07 vs 0.18 ± 0.08; P = .03). In conclusion, this study suggests that the superior hemodynamic performance of stentless bioprostheses may have some benefits with regard to LV mass regression and function after aortic valve replacement. The significance of these benefits in terms of prognosis remains to be determined.
  • Publication
    Accès libre
    Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity and mortality after aortic valve replacement with a bioprosthetic heart valve.
    (ICR, 1998-03-01) Métras, Jacques; Lemieux, Michel; Cartier, Paul C.; Pibarot, Philippe; Dumesnil, Jean G.; Durand, Louis-Gilles
    BACKGROUND AND AIMS OF THE STUDY: Previous studies have shown that the effective orifice area of an aortic prosthetic valve may be too small in relation to the patient's body surface area, resulting in abnormally high gradients. The consequences of this condition, termed prosthesis-patient mismatch, have not been fully studied. The study objective was to determine if the condition has a detrimental effect on symptomatic and hemodynamic status, morbidity and mortality of patients undergoing aortic valve replacement. METHODS: A cohort of 392 patients was prospectively followed for up to seven years after implantation of a Medtronic Intact bioprosthesis. Doppler echocardiography was performed annually in 72 patients. Based on previous studies, presence of mismatch was defined as an indexed valve area < or = 0.85 cm2/m2. RESULTS: Mismatch was associated with less postoperative improvement of NYHA functional class (p < 0.009) independently of other predictors, such as age and preoperative functional class, but had no significant impact on patient survival (mismatch: 75 +/- 4%, no mismatch: 79 +/- 3%; p = 0.59) and valve-related morbidity up to seven years. Cardiac index was similar in patients with and without mismatch up to three years after operation but decreased significantly thereafter only in patients with mismatch (-0.54 +/- 0.32 versus -0.17 +/- 0.49 l/min/m2; p = 0.04). Likewise, the mean transprosthetic gradient, which was higher at one year after operation in patients with mismatch (22 +/- 8 versus 15 +/- 7 mmHg), increased significantly (+6 +/- 6 versus +1 +/- 1 mmHg; p = 0.008) only in this group during follow up. CONCLUSIONS: Patients with mismatch have less symptomatic improvement and worse hemodynamics that continue to deteriorate with time. However, medium-term prognosis (up to seven years) is relatively good. Further studies are necessary to determine the longer-term effects of mismatch on morbidity and mortality.
  • Publication
    Midterm follow-up of unstented biological valves
    (W.B. Saunders, 1999-10-01) Métras, Jacques; Lemieux, Michel; Cartier, Paul C.; Pibarot, Philippe; Dumesnil, Jean G.
    We have used the stentless aortic biosprosthesis for aortic valve replacement during the last 10 years. Since 1988, 647 stentless aortic prosthesis were implanted: 384 unstented heterografts, 176 Ross procedures, and 87 homografts. Patients up to age 50 were offered the Ross procedure, those between the ages of 50 and 60 a homograft, and patients 60 years old and older received heterografts. All patients were evaluated at our clinic. An echocardiogram was obtained before discharge from the hospital, at 3 to 6 months postoperatively, and yearly thereafter. Gradients, regurgitation, and effective orifice area were recorded at each visit. The patient was also evaluated clinically. Early mortality rate was 5.4%, 1.7%, and 5.8% for heterograft, autograft, and homograft, respectively. The mean gradient for the unstented porcine valve was 7.6 mm Hg at 3 to 6 month but 5 mm Hg or less for the homografts or autografts. Unstented valves are relatively new but they showed superior hemodynamic performance compared with either mechanical or biological stented valves. Anticoagulation is not mandatory, which should decrease the number of complications. They are the replacement of choice for young and old patients with a small aortic root and are the best alternative to the natural valve.