Transcript Prosthetic Valves - Harvard University

Echocardiographic
Evaluation of Prosthetic
Heart Valves
Patricia Tung, M.D.
February 10, 2010
Objectives
 Types
of prostheses
 Prosthetic dysfunction
 Echocardiographic surveillance of
prostheses
Types of Prostheses
 Mechanical
valves
 Tissue valves
 Homograft valves
Mechanical Valves
Tissue Valves
Homograft Valves
Objectives
 Types
of prostheses
 Prosthetic dysfunction
 Echocardiographic surveillance of
prostheses
Mechanisms of Prosthetic Valve
Dysfunction
 Structural


failure
Stenosis
Regurgitation
 Thromboembolic
complications
 Endocarditis
 Patient
Prosthesis Mismatch
Structural Failure Bioprosthetics
Cohn et al.
Ann Thorac Surg,
1998.
Homograft Dysfunction
 Subject
to severe tissue calcification
 Usually reserved for complex aortic root
abscesses
 Hyperlipidemia accelerates prosthesis
calcification
 Secondary prevention may slow this
process
Physical Exam Findings
Echocardiographic Evaluation
TTE
 valve area and regurgitation
 exclude significant obstruction
 Flow velocity is crucial measurement
 Often inadequate for infection or small
structural changes (strut fracture, small
vegetation, paravalvular leak)
TEE
 inspection of valve apparatus and seating
 may not accurately quantify valve flow
velocities
Normal Appearance PV
Normal Doppler Clicks
Normal Doppler Flow Patterns
Fluid Dynamics and Velocities
Normal Finding: Regurgitation
Pathologic Regurgitation
Characterized by:




An eccentric or large jet
Marked variance on the color flow display
A jet that originates around the valve sewing
ring
Visualization of a proximal flow acceleration
region on the LV side of the mitral valve
Prosthetic Valve Regurgitation
Prosthetic Valve Stenosis
Pressure gradients
- Calculated using the Bernoulli equation (4v2)
- Good correlation when validated against
invasive pressure measurements
- mechanical valves, especially bileaflet, result
in overestimation of the gradient due to
differing fluid dynamics
Prosthetic Aortic Valve Area
Prosthetic AVA: Velocity Ratio
 Measure
velocity increase across valve
 Ratio of outflow tract velocity/aortic jet
velocity reflects degree of stenosis
 Ratio = 1 if no obstruction present
 Given inherent stenosis, normal range is
0.35 to 0.5 for aortic prosthesis
Prosthetic Mitral Valve Area
 Can
be estimated using the pressure halftime approach as for native mitral valve
stenosis.
 The expected half-time for a PV is longer
than with a native valve.
Prosthetic Valve Thrombosis

TEE is often negative if
the thrombi are small or if
new thrombus has not
formed since the initial
embolic event.
 Thus an embolic event in
a patient with a prosthetic
valve (esp mechanical)
must be presumed to be
related to the PV even if
the TEE is negative.
Prosthetic Valve Endocarditis
 Difficult
to detect with TTE
 Often involves sewing ring and annulus,
resulting in paravalvular abscess rather
than a discrete vegetation
Prosthetic Valve Endocarditis
Patient Prosthesis Mismatch
 Size
of prosthesis results in inadequate
blood flow given metabolic demands
 Prosthesis itself functions well
 Indexed effective orifice area < or =
0.85cm2/m2
 Predicts high transvalvular gradients,
persistent LVH and increased rate of
cardiac events following AVR
Objectives
 Types
of prostheses
 Prosthetic dysfunction
 Echocardiographic surveillance of
prostheses
Recommended Surveillance
 Baseline
echocardiogram 6-8 weeks
postoperatively
 Routine echocardiographic surveillance
annually thereafter
 Evaluate for



Regression of hypertrophy or dilation
Recovery of LV systolic function
Changes in PA pressures
Summary

Prosthetic valve dysfunction is well detected by
echocardiography
 Dysfunction includes





Structural failure
Thromboembolic complications
Endocarditis
PPM
Distinguishing normal from pathologic function
can be challenging; most useful is comparison to
baseline post-prosthesis
References




Otto, C. Textbook of Clinical Echocardiography, Fourth Edition 2009.
Libby et al. Braunwald’s Heart Disease. Eighth Edition 2008.
Pibarot, P and Dumesnil JG. Prosthesis-patient mismatch: definition,
clinical impact, and prevention. Heart 2006;92:1022-1029
Bonow RO, Carabello BA, Chatterjee K, et al: ACC/AHA 2006
guidelines for the management of patients with valvular heart
disease: A report of the American College of Cardiology/American
Heart Association Task Force on Practice Guidelines (writing
committee to revise the 1998 Guidelines for the Management of
Patients with Valvular Heart Disease): Developed in collaboration
with the Society of Cardiovascular Anesthesiologists: endorsed by
the Society for Cardiovascular Angiography and Interventions and
the Society of Thoracic Surgeons. Circulation 2006; 114:e84.