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Echo in prosthetic valve evaluation
Echocardiography is the main tool for evaluating prosthetic heart valves. Transthoracic echocardiography (TTE) is generally used to assess normal valve function and identify dysfunction like stenosis or regurgitation. Transesophageal echocardiography (TEE) provides better imaging of valve structure and is helpful for evaluating regurgitation and complications like endocarditis. Echocardiograms establish a baseline after valve implantation and monitor for issues like pannus, thrombus, infection or degeneration over time. TTE and TEE are complementary, with TEE used when TTE is inadequate or clinical suspicion remains after a TTE.
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Echo in prosthetic valve evaluation
- 1. Echocardiographic evaluation of ProstheticValves Dr.Sruthi Meenaxshi, MBBS,MD,PDF
- 7. • Echocardiography isthe key noninvasive modality for evaluation of prosthetic valve structure and function • Transthoracic echocardiography (TTE) is the mainstay for monitoring prosthetic valves and can generally identify normal function as well as evidence of valve dysfunction (stenosis). • Transesophageal echocardiography (TEE) is helpful particularly for assessment of valve structure and prosthetic valve regurgitation especially involving mechanical mitral and tricuspid prostheses as well as assessment of endocarditis for all valves • This topic will review echocardiography of prosthetic heart valves
- 10. Baseline transthoracic echocardiogram AmericanHeart Association/American College of Cardiology (AHA/ACC) guideline recommendation to perform a transthoracic echocardiogram (TTE) six weeks to three months after valve implantation (when the hemoglobin has normalized) to evaluate valve hemodynamics and to establish a baseline for future comparison The TTE should include Doppler measurements of transvalvular velocities as well as assessment of valvular and paravalvular regurgitation. Adequate Doppler velocity recordings can generally be obtained despite acoustic shadowing from valve prostheses.
- 11. • Transvalvular gradientsfor normally functioning prosthetic valves are dependent upon • valve type • location • size (as compiled in the 2009 American Society of Echocardiography guidelines as well as patient-specific factors • A higher than expected initial gradient is often due to a high output state (eg, due to anemia) or patient-prosthetic mismatch • It is only rarely due to early dysfunction of the prosthesis (eg, thrombus formation or hemodynamically significant valvular regurgitation) • We suggest obtaining the postoperative baseline study after the patient’s hemoglobin has returned to baseline to avoid recording a gradient that is transiently higher than expected due to anemia.
- 12. Change in clinicalstatus The echocardiographer should be alert to the range of complications that can occur with prosthetic devices, including the following Prosthetic obstruction due to thrombus, pannus ingrowth, leaflet thickening, or calcification of biologic prostheses.
- 13.
- 14. • Prosthetic regurgitationdue to paravalvular leak, prosthetic leaflet interference by thrombus, or vegetation or leaflet tear of a bioprosthesis.
- 15. Prosthetic valve endocarditis •findings including vegetations and abscess formation • ●Prosthetic valve dehiscence with valve ring instability/"rocking." • ●Mechanical structural failure (eg, strut fracture and component escape), which is rare with current valve types.
- 16. • A TTEis recommended as the initial test in patients with prosthetic valves with a change in clinical status suggestive of valve dysfunction and/or endocarditis • Symptoms and signs of bioprosthetic valve degeneration, • pannus formation, or • endocarditis include new exertional dyspnea, • a louder murmur, or a new murmur. • Symptoms and signs of mechanical valve dysfunction due to thrombosis, pannus formation, or endocarditis include a new or louder murmur, new onset of dyspnea, and signs of heart failure, thromboembolism, and hemolysis.
- 17. • For patientswith a prosthetic valve, a TTE may also be useful since it provides proper alignment for Doppler assessment of transvalvular velocities, gradient, and valve area. • In patients with aortic prostheses, valvular regurgitation can be reliably detected on TTE. • For all patients with a prosthetic valve, TTE may be useful for assessment of biventricular cavity size and systolic function as well as an estimate of pulmonary artery systolic pressure.
- 18. • Transesophageal echocardiographyhas much higher sensitivity for detection of • prosthetic valve thrombi • vegetations • extravalvular extension of infection as well as prosthetic mitral regurgitation.
- 19. Surveillance of oldbioprosthetic valves Since the incidence of bioprosthetic valve dysfunction markedly increases 10 years after implantation, we agree with the 2014 AHA/ACC valve guidelines, which state that a TTE is reasonable in patients with a bioprosthetic valve after the first 10 years, even in the absence of change in clinical status The guideline suggested annual TTE thereafter, but every two to three years may be reasonable if valve function is normal with annual echocardiograms when valvular dysfunction presents.
- 20. • However, inindividuals at increased risk of early valvular degeneration such as those with chronic renal failure and young age at implantation, it is reasonable to repeat echocardiography at five years post-implantation and yearly thereafter • Routine annual echocardiographic evaluation is not indicated in patients with mechanical valve prostheses with normal postoperative baseline examination and no signs or symptoms of valve dysfunction
- 21. KEY COMPONENTS OFTHE ECHOCARDIOGRAM Echocardiographic evaluation of patients with prosthetic valves includes imaging of the valve and its seating; assessment of valve hemodynamics transvalvular velocities identification and quantification of valve regurgitation (intravalvular and paravalvular); measurement of cardiac chamber sizes left ventricular wall thicknesses assessment of left ventricular systolic and diastolic function
- 22. • Prosthetic valvesare generally inherently stenotic, so Doppler velocity recordings across normally functioning valves are similar to those of mild native valve stenosis • Normal function of the valve is confirmed by • evaluation of the contour of the jet velocity • acceleration time (the time from onset of flow to maximal velocity), • the effective orifice area (EOA) • Doppler velocity index (DVI).
- 23. • An increasein the transprosthetic velocity could be due to • valvular obstruction, • regurgitation, or an • increase in cardiac output, • Decrease in either the EOA or the DVI is more specific for prosthetic obstruction. A Doppler velocity pattern demonstrating normal transprosthetic flow gradient and flow duration is usually sufficient to exclude a stenotic valve However, the gradient may not be elevated in the setting of obstruction with low stroke volume. • The EOA is calculated using the continuity equation: • EOA = stroke volume/VTIPrV
- 24. • where VTIPrVis the velocity time integral through the prosthesis determined by continuous wave Doppler. • The stroke volume is generally derived from an adjacent site as cross-sectional area (estimated from the associated diameter and assuming a circular area) multiplied by the VTI of flow measured by pulsed wave Doppler at that site. • For prosthetic aortic and pulmonic valves, site for calculation of stroke volume is at the site of flow just proximal to the valve. • For prosthetic mitral valves, stroke volume may be calculated at the aortic or pulmonary annulus if no significant regurgitation is present.
- 25. Doppler velocity indexor dimension less index • The DVI is a simplified method for evaluating aortic valve obstruction. • The DVI is the ratio of the velocity proximal to the valve by pulsed wave Doppler to the velocity through the valve by continuous wave Doppler. • Use of this index avoids the need to measure stroke volume • A DVI <0.25 suggests significant valve obstruction.
- 26. • Prosthetic aorticregurgitation (intravalvular or paravalvular) can generally be identified by transthoracic echocardiography (TTE). • Prosthetic mitral regurgitation and tricuspid regurgitation are usually difficult to assess on TTE due to acoustic shadowing and thus transesophageal echocardiography (TEE) is preferred.
- 27. Role of TTEand TEE TTE and TEE are complementary in the evaluation of prosthetic valves. As mentioned, acoustic shadowing caused by prosthetic material may limit TTE visualization of prosthetic discs/leaflets, vegetations, abscesses and thrombi. In addition, while prosthetic aortic valve regurgitation is usually well visualized on TTE color Doppler imaging, prosthetic mitral regurgitation is frequently undetectable As a result, TEE is the imaging method of choice when the TTE is technically inadequate or when there are borderline findings on the TTE in a patient in whom there is a strong clinical suspicion of prosthetic malfunction
- 28. Complications of prostheticvalve • Paravalvular leak • Endocarditis • Extrinsic interference of function (pannus, thrombus, vegetation) resulting in obstruction and/or regurgitation • Leaflet tears of bioprosthesis • Leaflet calcification/stenosis of bioprosthesis • Ball variance, now rare as ball in cage valves are no longer implanted • Strut fracture and component escape, also now rare with newer-generation valves
- 29. • It isworth mentioning the finding of microbubbles, which can be seen in an otherwise normally functioning mechanical prosthesis and are not associated with valve pathology. • They are usually seen with mitral prostheses within the left ventricular inflow and are likely due to degassing of carbon dioxide
- 30. FEATURES OF VALVEDYSFUNCTION • Prosthetic valve obstruction — • Prosthetic valve obstruction should be suspected in a newly symptomatic patient with a rise in transprosthetic gradient from a baseline determination or from established normal values for valves of that type and size. • The expected range of Doppler gradients and effective orifice area encountered in properly functioning valves.
- 31. Pannus formation ina st judes valve
- 32. Thrombus formation inSt judes mechanical Prosthetic valve . After successful thrombolysis mean gradient hasd significantly reduced
- 34. • Causes ofobstruction include pannus ingrowth, thrombus, and vegetation • Clinical clues to this possibility include the age of the valve and the adequacy of anticoagulation. In a bioprosthesis or heterograft, the leaflets themselves may become calcified and immobile. • There has been an increasing recognition of subclinical thrombus formation on bioprosthetic valves, which appears to be more common in percutaneous valves than in surgically placed valves as discussed separately
- 35. • Once thereis a high suspicion of obstruction, transesophageal echocardiography (TEE) should be performed for etiologic definition with both mechanical and bioprosthetic valves, especially for mitral prostheses. • Doppler transthoracic echocardiography (TTE) is the primary means to diagnose prosthetic valve obstruction; hemodynamic cardiac catheterization is not routinely needed • 3D-TEE may be helpful in identifying pannus, although its utility has not been well defined • Computed tomography (CT) scan is an important adjunctive imaging modality.
- 36. • In thecase of suspected aortic pannus, the distal end of the left ventricular outflow tract should be examined both with imaging and with color flow Doppler. • Pannus tends to lie close to the valve ring and can be easily overlooked.
- 37. • In themitral position, the same procedure should be followed. • Finding a high grade of spontaneous contrast in the left atrium, with or without thrombi, or finding thrombus around the sewing ring in the setting of adequate anticoagulation should heighten suspicion of pannus formation. • Thin fibrillar strands may also be encountered adjacent to the mitral annulus and on the sewing ring of the valve. • These structures are brightly reflective and highly mobile and may or may not be associated with a pathologic process.
- 38. Distinction between thrombusand pannus • The most common etiology for prosthetic valve obstruction is thrombus formation; pannus formation due to fibrous tissue ingrowth is far less common. • Since treatment options for thrombus and pannus differ, it is important to distinguish between these two causes.
- 39. • Echocardiographic differentiationof pannus and thrombus may be difficult. In general: • ●Thrombus tends to be larger, mobile, be somewhat less echo-dense, and more commonly associated with spontaneous echo contrast. • ●Pannus is highly echogenic, consistent with its fibrous composition; is usually firmly fixed (minimal mobility) to the valve apparatus; and mostly involves the sewing ring, which may make it difficult to distinguish from the ring
- 40. • In orderto establish factors associated with the presence of thrombus, one study evaluated the findings on a preoperative TEE in 53 patients with an intraoperative diagnosis of pannus or thrombus • Predictors of thrombus or a mixed presentation (pannus and thrombus) included: Mobile mass Attachment of mass to valve occluder Elevated gradients An international normalized ratio ≤2.5
- 41. Prosthetic valve regurgitation •Physiologic regurgitation, the so-called "seating puff" of angiography, is universally encountered with mechanical valves and dependent in degree on the type of prosthesis used. • However, severe regurgitation may result from bioprosthetic valve leaflet degeneration or destruction from endocarditis, mechanical valve pannus, thrombus, or vegetation that interferes with mechanical leaflet function.
- 42. Physiologic regurgitation All mechanicalvalves exhibit some degree of obligatory regurgitation of up to 15 mL of blood The physiologic regurgitation associated with prosthetic valves appears only briefly and is due to retrograde volume displacement as the valve leaflets close . This type of regurgitation is detected by highly sensitive color flow Doppler imaging on TEE. In addition, a certain amount of more prolonged "leakage backflow" regurgitation occurs after the valve closes . These are often referred to as "washing jets," believed to inhibit the formation of thrombi.
- 43. • Normally functioningmechanical valves, such as the bileaflet St. Jude prosthesis, usually have two to four centrally directed regurgitant jets. • Features associated with these jets include a low intensity and only minimal penetration into the atrium, generally less than 3 cm • The monodisc Medtronic-Hall valve has two jets, one of which is prominent and longer • Normally functioning bioprosthetic and heterografts are less likely to have these small regurgitant signals; when mild regurgitation is present, there is usually one central jet
- 44. Pathologic regurgitation • Mostpathologic regurgitation associated with mechanical valves is perivalvular. • However, occasionally, disc closure may be impeded by a vegetation or thrombus leading to combined stenosis and regurgitation. • If TTE does not reveal the offending mass or tissue, TEE should be performed. • Bioprostheses with leaflet degeneration may exhibit central pathologic regurgitation that is broad-based when severe.
- 45. Paravalvular regurgitation • —Trace or mild paravalvular regurgitation immediately following valve replacement is common with both mechanical and bioprosthetic prostheses and generally not progressive. • Paravalvular regurgitation can develop late after valve replacement due to suture dehiscence, from a poorly seated ring, or from endocarditis leading to valve dehiscence. • Hemolysis is a common complication of these leaks, especially when they occur with a mitral valve prosthesis • Paravalvular regurgitation should be suspected when a patient with a prosthetic valve presents with hemolytic anemia.
- 46. • To recognizea paravalvular leak, TEE must be performed with a high color frame rate in several views from several angles outside the sewing ring • There should be a careful search for periprosthetic leaks around as much of the valve circumference as possible and an attempt made to define the extent of the regurgitation once it is identified. • The origin of a periprosthetic leak may appear deceptively narrow when caused by disruption of a limited number of sutures. • Three-dimensional echocardiography is helpful in mapping the extent of the paravalvular leak and has proven efficacious for guiding percutaneous device closure of these leaks.
- 47. Prosthetic valve dehiscence •Prosthetic valve dehiscence is identified on echocardiography as a separation of the prosthetic ring from the native valvular annulus and is usually accompanied by paravalvular regurgitation. • Valve dehiscence is most frequently caused by endocarditis. • Rocking of a prosthetic valve is a sign of dehiscence, particularly in the aortic position. • Rocking of a prosthetic mitral valve can be caused by dehiscence or by retained native posterior leaflet or posterior and anterior leaflets, with the latter generally not accompanied by paravalvular regurgitation • Prosthetic valve dehiscence may be identified by TTE but is frequently better visualized with TEE
- 48. Thromboembolism • In patientswith a suspected cardiac cause for embolism, the source may be a thrombus from a nonobstructed or obstructed prosthetic heart valve.
- 49. SPECIFIC PROSTHETIC VALVE DISORDERS •Prosthetic aortic stenosis — Aortic prosthetic obstruction may be due to thrombus or vegetation, pannus ingrowth, or progressive leaflet degeneration in the case of a bioprosthetic valve.
- 51. • we agreewith the American Society of Echocardiography algorithm for diagnosis of prosthetic aortic stenosis • ●If the peak velocity across the aortic prosthesis is greater than 3 m/sec or if there is a significant increase over baseline, the Doppler velocity index (DVI) should be calculated.
- 52. Doppler velocity indexor dimensionless index
- 53. Algorithm of prostheticvalve assessment in aortic valve
- 54. • Further analysisshould include measurement of the acceleration time (AT), which is the time from transvalvular flow onset to maximal velocity • An AT <100 msec is consistent with normal function, whereas an AT >100 msec is concerning for obstruction and further evaluation is warranted. • A DVI <0.25 suggests prosthetic aortic valve stenosis if accompanied by an AT >100 msec.
- 55. • Finally, theeffective orifice area (EOA) indexed by body surface area can provide evidence of patient-prosthetic mismatch when the transprosthetic velocity is high but the DVI is >0.25 and the AT is <100 msec. • Patient-prosthetic mismatch is suggested by an EOA index of <0.8 cm2/m2 and is considered severe when the EOA index is <0.65 cm2/m2
- 56. • When prostheticaortic valve stenosis is suspected, the transthoracic echocardiography (TTE) is usually not adequate for visualization of the leaflet motion or presence of thrombus and thus warrants further investigation with fluoroscopy of a mechanical valve and/or transesophageal echocardiography (TEE)
- 57. Prosthetic aortic regurgitation Mechanicalprosthetic valves displace blood when the occluder disc closes and may also have small holes in the occluders and at hinge points; the pattern is characteristic for the valve type • Biologic valves may have minor degrees of central regurgitation, which are detectable due to the high sensitivity of color flow Doppler.
- 59. • Grading theseverity of pathological prosthetic aortic regurgitation can be challenging and an integrative approach is recommended • When there is significant dehiscence of the valve (more than 40 percent), a rocking motion is detected, which is usually associated with severe regurgitation. • The following features suggest severe regurgitation: jet width >65 percent, pressure half-time <200 msec, holodiastolic flow reversal in the descending aorta, regurgitant volume >60 mL, and a regurgitant fraction >50 percent • In addition, chronic severe aortic regurgitation is a cause of left ventricular dilation.
- 60. • While TTEcan detect and often grade prosthetic aortic regurgitation, the cause is often not apparent. • TEE should be performed in order to diagnose endocarditis with or without abscess, thrombus interfering with disc closure, and bioprosthetic leaflet tears.
- 61. Prosthetic mitral stenosis •Prosthetic mitral valve obstruction can also occur because of thrombus, pannus, vegetation, and bioprosthetic leaflet thickening or calcification. • The peak transmitral velocity, the mean gradient, and pressure half-time should all be considered in the context of the heart rate and compared with previous echocardiographic studies.
- 62. Prosthetic mitral regurgitation •Since the color Doppler jet is usually obscured because of acoustic shadowing caused by the prosthesis, other clues to regurgitation must be heeded • There may be increased rocking of the prosthesis associated with dehiscence of the sewing ring. • The peak transmitral E wave velocity is increased as is the mean gradient, although the pressure half-time remains within normal range. • The left ventricular volume may be increased and the ejection fraction is usually preserved. • However, in the presence of significant mitral regurgitation, the forward stroke volume falls, which can be inferred by a decrease in the left ventricular outflow tract VTI.
- 64. Prosthetic tricuspid valvedysfunction • The principles for evaluating the prosthetic tricuspid valve are similar to that of the mitral valve. • Bioprostheses are more commonly used than mechanical prostheses in the tricuspid position due to issues of valve thrombosis. • Because of the respirophasic variation in transtricuspid velocities, at least five beats should be measured.
- 65. summary • Transthoracic echocardiography(TTE) is helpful in evaluating prosthetic valve function, particularly valve gradients, but views are frequently limited for assessment of vegetations, thrombus, and regurgitation, especially for mitral and tricuspid prostheses. • ●Transesophageal echocardiography (TEE) is particularly helpful in detecting paravalvular leak, prosthetic mitral and tricuspid regurgitation, vegetation, abscess, valve obstruction, ball variance, strut fracture and component escape, bioprosthetic leaflet tears, and bioprosthetic calcification/stenosis. • As a result, initial TEE is often preferred. A TTE may be more useful to assess chamber sizes and ventricular function.
- 66. • ●A TTEwith Doppler measurements of transvalvular velocities obtained six weeks to three months after prosthetic valve implantation (when the hemoglobin has normalized) is helpful to establish a baseline for future comparison. • ●Complications of prosthetic valves include prosthetic valve obstruction, regurgitation, endocarditis, dehiscence, and mechanical structural failure (rare with current valve types). • ●We suggest monitoring by TTE starting 10 years after implantation of a bioprosthetic valve due to the risk of valve degeneration. • However, in patients with risk factors for early deterioration such as those with renal failure and implantation at younger ages, it is reasonable to start monitoring at five years.
- 67. • Trace ormild paravalvular regurgitation immediately following valve replacement is common and generally not progressive. Paravalvular regurgitation can develop late after valve replacement due to broken or dehisced sutures, from a poorly seated ring, or from endocarditis (dehiscence • ●Prosthetic valve obstruction should be suspected when a patient develops symptoms of heart failure and increased transprosthetic gradient. TEE is the primary means to confirm prosthetic valve obstruction and investigate its causes (pannus, thrombus, or vegetation). • ●Pathologic, intense prosthetic valve regurgitation can result from bioprosthetic valve degeneration, mechanical valve pannus, thrombus, or vegetation • ●Systemic emboli can arise from nonobstructive or obstructive valve thrombosis.