Rapid deployment aortic valves deliver superior hemodynamic performance in vitro

Aim

To develop a clinically relevant aortic root model, and then compare the haemodynamic function of the EDWARDS INTUITY valve (a rapid deployment valve) with the Carpentier- Edwards PERIMOUNT Magna Ease valve (a conventional bioprosthetic valve), in vitro.

Background Information

Many trials have shown the short-term safety and efficacy of sutureless rapid deployment aortic valves, but direct comparisons of the haemodynamic performance of these new valves with conventional bioprosthetic valves are lacking.

Methods

Model development

Multi-slice computed tomography reconstructions in patients with aortic stenosis were used to generate a 3D printed model of an aortic root.

Effective diameter of the aortic annulus was 21 mm, effective area was 3.38 cm2 and LVOT area was 3.01 cm2.

Valve Deployment

Figure 1: EDWARDS INTUITY and Magna Ease valves in the aortic root model and cadaver heart

A: EDWARDS INTUITY valve in the model;

B: Magna Ease valve in the model without pledgets;

C: Magna Ease valve in the model, with pledgets;

D: Outflow view of the aortic root model; E: EDWARDS INTUITY valve in the cadaver heart;

F: Magna Ease valve without pledgets in the cadaver heart.

Results

Hemodynamic Performance

The EDWARDS INTUITY valve had both a greater EOA and a lower TPG than the Magna Ease valve, irrespective of pledget use (Figure 1). EOA
and TPG were also significantly different between Magna Ease valves with and without pledgets (all p<0.002 or 0.001).

LVOT Performance

Expanding the EDWARDS INTUITY valve frame diameter from 22 to 25 mm increased the average LVOT area index stepwise from 1.07 to 1.34: this minimally affected EOA or TPG (Table 1).

EDWARDS INTUITY valves resulted in more circular LVOTs than Magna Ease valves, although increasing ellipticity did not impact EOA or TPG.

Average maximum flow velocity was lower across the EDWARDS INTUITY valve than the Magna Ease valve without pledgets (p<0.003), as were maximum turbulent shear stress (p<0.02) and turbulent kinetic
energy (p<0.002).

EOA: effective orifice area

Table 1: TPG and EOA of models with an EDWARDS INTUITY valve or a Magna Ease valve (with or without pledgets)

Limitations

• Such a model, isolated from the left ventricle, cannot replicate all physiological mechanical properties.
• Pathological changes and normal physiological variations can affect valve performance in vivo: these were not modelled here.
• The use of saline, rather than blood or a substitute, may have affected simulated valve performance.

Conclusions

• Haemodynamic performance was superior for the EDWARDS INTUITY valve than the Magna Ease valve with increased EOA and reduced mean gradient.
• Pledgets worsened Magna Ease valve performance.
• Maximum velocity, turbulent shear stress and kinetic energy were all lower across the EDWARDS INTUITY valve than the Magna Ease valve.
• Haemodynamic advantages may account for the superior clinical performance of rapid deployment valves over conventional surgical valves