Ex vivo hemodynamic assessment of mechanical aortic valve gradients using a high-fidelity pressure wire.

OBJECTIVES

Accurate assessment of prosthetic mechanical valve malfunction is challenging for non-invasive and invasive techniques. We evaluated a 0.014-inch pressure-sensing coronary guidewire to assess mechanical valve dysfunction.

BACKGROUND

Several case reports have shown that transaortic pressure gradients can be recorded using a 0.014-inch guidewire during cardiac catheterization.

METHODS

We performed an ex vivo study measuring the effects of sequentially crossing the center of each valve with a 6 French coronary angiographic catheter, a 0.035-inch guidewire, and a 0.014-inch pressure-sensing guidewire on valve dysfunction using the following 23 mm bileaflet and tilting-disc aortic valves: St. Jude Regent™, CarboMedics, Medtronic Hall™, and Björk-Shiley Monostut. A left heart model pulse duplicator recorded 10 consecutive cycles.

RESULTS

For all valves, the greatest increase in valve regurgitation occurred with the 6 French catheter, causing a reduction in aortic valve back pressure and cardiac output, with an increase in leakage rate, regurgitant fraction, and energy loss. In comparison to the 0.035-inch guidewire, the 0.014-inch guidewire had greater regurgitation for St. Jude, lower for Medtronic Hall, and equivalent for CarboMedics and Björk-Shiley valves. For the CarboMedics valve, the 0.035-inch guidewire caused a significant increase in regurgitant fraction and energy loss, while the pressure wire had no change compared to baseline.

CONCLUSIONS

The degree of regurgitation caused by the 0.014-inch guidewire varies with the type of mechanical aortic valve. While prior case reports have shown that valve hemodynamics may be measured using a pressure-sensing guidewire, valve regurgitation occurs when crossing a St. Jude, Medtronic Hall, or Björk-Shiley aortic valve.