The present invention provides a positive displacement apparatus for selectively translating a completion tool, such as an expander tool, downhole. A shield is mounted with the needle and extensible, via a tubular needle guide movable along the needle, between a retracted position and an extended position. Ventricular pacing is available in a cardiac cycle immediately subsequent to such a skipped beat. A support ring fixed to the actuator and to the guide forms with the guide-body end an annular chamber into which the valve opening opens and is formed with a radially throughgoing port opening into the chamber and radially aligned with the valve opening. Wound strips may alternate with spaced strips and spacers between the strips enhance web buckling strength. The IR receiver may receive signals from a remote and pass them through to a device, such as a device used in a home theater system, with a built in IR receiver via the IR output.