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CHAPTER 13: Prosthetic Valves

GUIDELINES Source

  • Zoghbi WA, Chambers JB, Dumesnil JG, et al. Recommendations for evaluation of prosthetic valves with echocardiography and Doppler ultrasound. J Am Soc Echocardiogr. 2009;22:975–1014.

  • Side-by-side images in this document illustrate normal and abnormal prosthesis function.

  • Tables 13-1 and 13-2 provide parameters for mild and severe prosthesis malfunction.

  • There are echo parameters for comprehensive evaluation.

Source

  • Lancellotti P, Pibarot P, Chambers J, et al. Recommendations for the imaging assessment of prosthetic heart valves. Eur Heart J Cardiovasc Imaging. 2016;17:589–590.

  • This is an extensive document that covers all topics related to prosthetic valves.

  • The digital version should be downloaded and used for reference.

Source

  • Rosenhek R, Binder T, Maurer G, Baumgartner H. Normal values for Doppler echocardiographic assessment of heart valve prostheses. J Am Soc Echocardiogr. 2003;16:1116–1127.

DOPPLER EVALUATION OF PROSTHETIC AORTIC VALVES

  • The simplified Bernoulli equation is used for gradients.

  • The gradient of prosthetic aortic valves may be overestimated by this method if:

    • - Cardiac output is increased.

    • - Left ventricular outflow is narrow.

    • - Prosthesis ring size is small.

    • - Proximal ascending aorta is small.

  • For continuity calculations of aortic prosthesis area:

    • - It is necessary to measure the outflow diameter directly.

    • - The label size of the prosthesis should not be used as a substitute.

  • The Doppler velocity index (DVI) is a simplification:

    • - It is the ratio of the velocity proximal to the valve and the velocity through the valve.

TABLE 13-1Normal vs. Stenotic Prosthesis
View Table||Download (.pdf)
TABLE 13-1 Normal vs. Stenotic Prosthesis
Aortic Prosthesis Normal Stenotic
Peak velocity <3 m/s >4 m/s
Mean gradient <20 mm Hg >35 mm Hg
Doppler velocity index >0.30 <0.25
Effective orifice area >1.2 cm2 <0.8 cm2
Jet velocity contour Triangular Rounded
Acceleration time <80 ms >100 ms

Note: Peak velocity and mean gradient are affected by increased systolic blood flow if there is an increase in stroke volume due to coexisting aortic prosthesis regurgitation.

Source

  • Bach DS. Echo/Doppler evaluation of hemodynamics after aortic valve replacement: principles of interrogation and evaluation of high gradients. JACC Cardiovasc Imaging. 2010;3:296–304. See Table 13-1.

PROSTHESIS BACKWASH

  • Prosthetic mechanical valves are intentionally designed to have small leaks by two mechanisms:

    • - Closure backflow: A certain amount of blood flow reversal is required to close the valve. Closure backflow stops once the occluder mechanism is properly seated in the sewing ring.

    • - Leakage backflow: This is a predesigned small amount of retrograde flow that continues after the occluder is properly seated and should not be interpreted as prosthesis malfunction.

PRESSURE RECOVERY

  • Pressure recovery offers an explanation for a higher Doppler gradient and lower catheterization gradient across a bileaflet aortic prosthetic valve.

  • The explanation:

    • - Kinetic energy is recovered in the form ...

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