A prospective randomized comparison of the Medtronic Advantage Supra and St Jude Medical Regent mechanical heart valves in the aortic position: Is there an additional benefit of supra-annular valve positioning?

A Meta-Analysis Examining Differences in Short-Term Outcomes between Sutureless and Conventional Aortic Valve Prostheses

Objective

Sutureless aortic valve prostheses are anchored by radial force in a mechanism similar to that of transcatheter aortic valve implantation. Transcatheter aortic valve implantation is associated with an increased permanent pacemaker (PPM) requirement in a significant proportion of patients. We undertook a meta-analysis to examine the incidence of PPM insertion associated with sutureless compared with conventional surgical aortic valve replacement.

Methods

A systematic review was conducted in accordance with the Prisma guidelines.1 All searches were performed on August 10, 2014. Studies between 2007 and 2014 were included in the search.

Results

A total of 832 patients were included in the sutureless group and 3,740 in the conventional group. Aortic cross-clamp (39.8 vs 62.4 minutes; P < 0.001) and cardiopulmonary bypass (64.9 vs 86.7 minutes; P = 0.002) times were shorter in the sutureless group. Permanent pacemaker implantation rate was higher in the sutureless cohort (9.1% vs 2.4%; P = 0.025).

Conclusions

Sutureless aortic valve prostheses are associated with significantly shorter cardiopulmonary bypass and aortic cross-clamp times and a higher incidence of PPM insertion than conventional. Further investigation of the prognostic significance is required.

Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

Introduction

In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench.

Objective

To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream.

Methods

To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. ) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements.

Results

It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found.

Conclusions

Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.

Intermittent regurgitation caused by incomplete leaflet closure of the Medtronic ADVANTAGE bileaflet heart valve: analysis of the underlying mechanism

OBJECTIVE

Clinical echocardiographic assessments of the Medtronic ADVANTAGE (Medtronic Inc, Minneapolis, Minn) prosthesis in the aortic position revealed a phenomenon identified as "intermittent regurgitation." An in vitro investigation was initiated to identify the underlying mechanism.

METHODS

In a pulse duplicator environment, 6 ADVANTAGE size 23 aortic valves were analyzed. Leaflet motion and flow through the valves were documented using echocardiography with color Doppler flow, digital high speed imaging, and flow meter assessment.

RESULTS

Intermittent regurgitation could be reproduced in all 6 of the tested valves within limited ranges of flow, pressure, and valve orientation. By virtue of high-speed imaging, the mechanism underlying intermittent regurgitation was identified. During intermittent regurgitation, the leading edge of the second-to-close leaflet makes contact with the chamfer on the leading edge of the first-to-close leaflet. The fluid closing forces working on the first-to-close leaflet prevent it from shifting back so that the leading edge of the second-to-close leaflet remains positioned against the chamfer of the first-to-close leaflet. In this position, the major radius of the second-to-close leaflet does not reach the housing's major radius. Therefore, a crescent-shaped gap remains between the leaflet tip of the second-to-close leaflet and the housing major radius during all or part of diastole. The regurgitant fraction can increase from a normal range of 6% to 25% during an intermittent regurgitation beat.

CONCLUSIONS

In vitro intermittent regurgitation can be induced in the size 23 aortic ADVANTAGE valve under a limited range of conditions. To avoid possible misinterpretations, the phenomenon must be known in detail by all physicians dealing with patients with an ADVANTAGE valve.