Does moderate mitral regurgitation impact early or mid-term clinical outcome in patients undergoing isolated aortic valve replacement for aortic stenosis?

OBJECTIVE: The early and mid-term impact of functional mitral regurgitation (MR) in patients undergoing isolated aortic valve replacement (AVR) for aortic stenosis remains unresolved. METHOD: Through our institutional databank, using a case-match study, we identified 58 patients with MR grades 0-1 and 58 patients with MR grades 2-3 (patients matched for sex, age, ejection fraction (EF), NYHA, diabetes, and CVA). Data were collected prospectively (mean duration of follow-up: 3.2 +/- 2.4 years). RESULTS: Perioperative morbidity (re-operation for bleeding, low cardiac output, CVA, renal failure) was comparable among groups. Difference in mortality between the two groups was non-significant (7.0 vs. 3.5%, P = 0.67 in groups MR 2-3 vs. 0-1, respectively). At early echocardiographic follow-up, 7/58 patients (12.1%) within group MR grades 0-1 increased their MR to grades 2-3; among which only two remained with MR grades 2-3 at mid-term follow-up. Within MR group 2-3, 18/58 (31.0%) remained with MR grades 2-3 among which 7/18 (38.9%) decreased of at least one grade at follow-up. Eight year actuarial survival was comparable in both groups: MR grades 0-1 = 60.9% vs. MR grades 2-3 = 55.0%; P = 0.1. Actuarial survival of patients with MR grades 2-3 postoperatively was similar to patients with MR grades 0-1 (MR grades 0-1 = 59.0%, MR grades 2-3 = 58.9%, P = NS). CONCLUSIONS: Presence of preoperative moderate functional MR (grades 2-3) in patients undergoing isolated AVR for aortic stenosis regresses in the majority of patients postoperatively and has no significant impact on perioperative morbidity or mortality, nor mid-term survival. Thus, moderate functional MR should be treated conservatively in the majority of patients especially in the elderly subjected to isolated AVR for aortic stenosis.

A single center experience with the freestyle bioprosthesis: midterm results at the Québec Heart Institute.

Stentless bioprostheses show excellent early hemodynamic performance. However, longevity still remains unknown. This study reports midterm follow-up in 419 patients in which a Freestyle bioprosthesis (Medtronic Heart Valves, Minneapolis, MN) was inserted between January 1993 and January 2000 at the Quebec Heart Institute (Ste-Foy, Québec, Canada). Mean age at implantation was 68.0 +/- 8.2 years. Implantation was subcoronary in 81.9% of the patients, as a root replacement in 16.5%, and as a root inclusion in 1.7%. Mortality at 30 days was 6.2% for the whole cohort (2.8% for isolated subcoronary aortic valve replacement). Female gender, root implantation, valve sizes 19 to 21 mm, previous surgery, a history of stroke and diabetes were identified as predictors of 30-day mortality. Actuarial freedom from all death causes was 81.5% at 7 years; freedom from valve-related deaths 97.0%, and freedom from cardiac deaths 92.7%. Freedom from thromboembolic events was 86.1% at 7 years (55.1% of events were < 30 days). Freedom from endocarditis and hemorrhagic complications were respectively 98.5% and 95.6% at 7 years. Six patients required reoperations for valve explantation: 2 for endocarditis, 2 for structural dysfunction, and 2 for nonstructural dysfunction. Incidence of moderate or severe valve insufficiency at annual echocardiographic follow-up was: discharge: 0.6%; year 1: 0.7%; year 2: 1.3%; year 3: 3.3%; year 4: 3.7%; year 5: 2.6%; year 6: 0%. At 6 years after implantation, mean transvalvular gradient and effective valve orifice area were comparable to the year 1 values. This single center experience with the Medtronic Freestyle prosthesis shows preserved hemodynamic performance and low valve-related complications at midterm.

Comparison of processed bovine internal mammary arteries and autologous veins as arterial femoral substitutes in dogs: blood compatibility and pathological characteristics.

This study was undertaken to compare the chemically processed internal mammary artery (BIMA) and the autologous femoral vein as arterial grafts. The BIMA prosthesis was implanted as a left femoral artery bypass and the femoral vein as a right femoral artery bypass graft in 27 dogs. In groups of three dogs the grafts were implanted for predetermined durations: 4, 24 and 48 hours (short term), 1, 2 and 4 weeks (medium term) and 3, 6 and 9 months (long term). All autologous veins were patent when the dogs were killed. The patency rates of the BIMA grafts were 100% in the short-term group, 67% in the medium-term group and 29% in the long-term group. The deposition of labelled fibrinogen and platelets on flow surfaces, the structural preservation of the wall of the BIMA prosthesis and accumulation of thrombi during the period of implantation were studied.

Hydrophilic polyurethane versus autologous femoral vein as substitutes in the femoral arteries of dogs: quantification of platelets and fibrin deposits.

Hydrophilic, microporous polyurethane vascular prostheses displayed good mechanical characteristics and the behaviour in vitro was excellent. The in-vivo results were, however, disappointing. To obtain a better understanding of the phenomena involved in the acute and early thrombosis, we implanted the polyurethane graft in the canine left femoral artery and an autologous femoral vein in the right for 4 and 24 h. At 4 h, one polyurethane graft was totally occluded and the other two were close to complete occlusion; at 24 h, none was patent. On the other hand, all autologous veins were patent. The thrombotic matrix incorporating both platelets and fibrinogen, quantified by labelling, was anchored along the anastomotic lines. This study confirms that polyurethane occlusion is initiated by hyperplastic reaction, but does not explain why.