The EVR valve has a shortened insertion profile that allows for transfemoral access in patients with challenging anatomy. The new delivery system, extended sealing skirt, and smaller implantation depth also have improved device performance. These features are associated with a higher success rate and reduced paravalvular leaks.
The armature of the valve has a plurality of radially spaced notches 86 on its peripheral edge. Air from the atmosphere is sucked into the armature by an adsorptive material 45. The flow passes through the center bore 36 and then through the air inlet 38. The magnetic fluid generated below 30% duty cycle is strong enough to lift the armature. This lifting action is achieved by a preloaded bias spring.
A preloaded armature bias spring is a common feature of conventional flow regulators. Its purpose is to urge the armature toward the “closed” valve position. It is usually adjusted to provide a preload of at least the minimum flow rate needed for the valve to operate at the specified “start-to-open” duty cycle. When the spring is adjusted, the vacuum differential is changed to match the vacuum output of the EVR valve at the selected duty cycle. This preload adjustment eliminates cumbersome calibration requirements.
The EVR chamber 82 is a circular-shaped cavity defined by the evr products inner diameter of the lower connecting flange 78 of the solenoid housing 72. Below the armature, the chamber 82 defines a primary air gap. This gap provides a net-build valve assembly and maintains the same primary air gap from unit to unit.
The electromagnetic solenoid assembly includes a passageway for communicating with the atmosphere, a reference chamber 108, an EVR chamber 82, and a vacuum inlet. The electromagnetic solenoid assembly also includes a control chamber 90. The control chamber is connected to the EVR chamber 82 via an orifice 105. The pressure differential between the armature and the atmosphere is controlled by the vacuum input at the connector 98. This signal is supplied by an electrical control signal from the ECU 22. The EVR chamber 82 is designed to enclose the armature’s lateral movement. Its inner diameter is greater than the armature’s.
The damping ring 110 is positioned above the armature and serves to attenuate the vacuum signal delivered to the vacuum regulator valve 14. The armature and the diaphragm valve assembly 92 are separated by a filter, which is located between the passageway and the damping ring. The filter is able to attenuate the vacuum signal and prevent oscillation of the diaphragm valve assembly if it is opened at less than 20% of the duty cycle. The damping ring also prevents the valve from opening at more than 15% of the duty cycle.
The delivery catheter has an outer diameter of 18.F, compared to 22F for the CV sheath. This has been found to reduce vascular complications in the EVR patient group. The EVR delivery catheter’s smaller insertion profile allows for transfemoral treatment in patients with iliofemoral vessels that are smaller than the typical common femoral artery.
