Peak early diastolic velocity rather than pressure half-time is the best index of mechanical prosthetic mitral valve function

Guidelines for the Evaluation of Prosthetic Valve Function With Cardiovascular Imaging: A Report From the American Society of Echocardiography Developed in Collaboration With the Society for Cardiovascular Magnetic Resonance and the Society of Cardiovascular Computed Tomography

In patients with significant cardiac valvular disease, intervention with either valve repair or valve replacement may be inevitable. Although valve repair is frequently performed, especially for mitral and tricuspid regurgitation, valve replacement remains common, particularly in adults. Diagnostic methods are often needed to assess the function of the prosthesis. Echocardiography is the first-line method for noninvasive evaluation of prosthetic valve function. The transthoracic approach is complemented with two-dimensional and three-dimensional transesophageal echocardiography for further refinement of valve morphology and function when needed. More recently, advances in computed tomography and cardiac magnetic resonance have enhanced their roles in evaluating valvular heart disease. This document offers a review of the echocardiographic techniques used and provides recommendations and general guidelines for evaluation of prosthetic valve function on the basis of the scientific literature and consensus of a panel of experts. This guideline discusses the role of advanced imaging with transesophageal echocardiography, cardiac computed tomography, and cardiac magnetic resonance in evaluating prosthetic valve structure, function, and regurgitation. It replaces the 2009 American Society of Echocardiography guideline on prosthetic valves and complements the 2019 guideline on the evaluation of valvular regurgitation after percutaneous valve repair or replacement.

Diagnosis of Left-Sided Mechanical Prosthetic Valve Thrombosis: A Pictorial Review

Although transcatheter valve therapy is rapidly evolving, surgical valve replacement is still required in many patients with severe left-side valve stenosis or regurgitation, the mechanical bi-leaflet heart valve being the standard prosthesis type in younger patients. Moreover, the prevalence of valvular heart disease is steadily increasing, especially in industrialized countries, and the problem of lifelong efficient anticoagulation of these patients remains fundamental, especially in the context where vitamin K antagonists continue to be the current standard of anticoagulation despite a level of oscillating anticoagulation. In this setting, avoiding prosthetic valve thrombosis after surgery is the number one objective for both the patient and the responsible physicians. Although rare, this complication is life threatening, with the sudden onset of acute cardiac failure such as acute pulmonary edema, cardiogenic shock, or sudden cardiac death and inadequate anticoagulation remaining the leading cause of prosthesis thrombosis, along with other risk factors. The availability of multimodal imaging techniques enables and encompasses to a full extent the diagnosis of mechanical valve thrombosis. The gold-standard diagnostic methods are transthoracic and transesophageal echocardiography. Moreover, 3D ultrasound has undoubted value in giving a more accurate description of the thrombus's extension. When transthoracic and transesophageal echocardiography are uncertain, the multidetector computer tomography examination is an important complementary imaging method. Fluoroscopy is also an excellent tool for evaluating the mobility of prosthetic discs. Each method complements the other to differentiate an acute mechanical valve thrombosis from other prosthetic valve pathologies such as pannus formation or infective endocarditis and aids the physician in accurately establishing the treatment method (surgical or pharmaceutical) and its optimal timing. The aim of this pictorial review was to discuss from an imagistic perspective the mechanical prosthetic aortic and mitral valve thrombosis and to provide an overview of the essential role of non-invasive exploration in the treatment of this severe complication.

Adverse Hemodynamic Conditions Associated with Mechanical Heart Valve Leaflet Immobility

Artificial heart valves may dysfunction, leading to thrombus and/or pannus formations. Computational fluid dynamics is a promising tool for improved understanding of heart valve hemodynamics that quantify detailed flow velocities and turbulent stresses to complement Doppler measurements. This combined information can assist in choosing optimal prosthesis for individual patients, aiding in the development of improved valve designs, and illuminating subtle changes to help guide more timely early intervention of valve dysfunction. In this computational study, flow characteristics around a bileaflet mechanical heart valve were investigated. The study focused on the hemodynamic effects of leaflet immobility, specifically, where one leaflet does not fully open. Results showed that leaflet immobility increased the principal turbulent stresses (up to 400%), and increased forces and moments on both leaflets (up to 600% and 4000%, respectively). These unfavorable conditions elevate the risk of blood cell damage and platelet activation, which are known to cascade to more severe leaflet dysfunction. Leaflet immobility appeared to cause maximal velocity within the lateral orifices. This points to the possible importance of measuring maximal velocity at the lateral orifices by Doppler ultrasound (in addition to the central orifice, which is current practice) to determine accurate pressure gradients as markers of valve dysfunction.

Usefulness of Mitral Valve Prosthetic or Bioprosthetic Time Velocity Index Ratio to Detect Prosthetic or Bioprosthetic Mitral Valve Dysfunction

This study aimed to investigate the utility of transthoracic echocardiographic (TTE) Doppler-derived parameters in detection of mitral prosthetic dysfunction and to define optimal cut-off values for identification of such dysfunction by valve type. In total, 971 TTE studies (647 mechanical prostheses; 324 bioprostheses) were compared with transesophageal echocardiography for evaluation of mitral prosthesis function. Among all prostheses, mitral valve prosthesis (MVP) ratio (ratio of time velocity integral of MVP to that of left ventricular outflow tract; odds ratio [OR] 10.34, 95% confidence interval [95% CI] 6.43 to 16.61, p<0.001), E velocity (OR 3.23, 95% CI 1.61 to 6.47, p<0.001), and mean gradient (OR 1.13, 95% CI 1.02 to 1.25, p=0.02) provided good discrimination of clinically normal and clinically abnormal prostheses. Optimal cut-off values by receiver operating characteristic analysis for differentiating clinically normal and abnormal prostheses varied by prosthesis type. Combining MVP ratio and E velocity improved specificity (92%) and positive predictive value (65%) compared with either parameter alone, with minimal decline in negative predictive value (92%). Pressure halftime (OR 0.99, 95% CI 0.98 to 1.00, p=0.04) did not differentiate between clinically normal and clinically abnormal prostheses but was useful in discriminating obstructed from normal and regurgitant prostheses. In conclusion, cut-off values for TTE-derived Doppler parameters of MVP function were specific to prosthesis type and carried high sensitivity and specificity for identifying prosthetic valve dysfunction. MVP ratio was the best predictor of prosthetic dysfunction and, combined with E velocity, provided a useful parameter for determining likelihood of dysfunction and need for further assessment.

Echocardiographic assessment of prosthetic mitral valves in children

AIMS

We studied how Doppler-derived hemodynamic parameters in children change as the relative prosthetic mitral valve (PMV) size decreases with somatic growth and evaluated the diagnostic utility of the parameters for detecting PMV obstruction in children.

METHODS AND RESULTS

We reviewed 26 echocardiographic examination results of 15 mechanical bileaflet PMVs in 12 children. The median age at echocardiographic examination was 6.6 (0.6-18.1) years. The PMV functioned normally in 24 examinations but was obstructed due to thrombosis in two cases. PMV sizes ranged between 16 and 25 mm, which were standardized to body surface area (BSA) at the examination with z-score calculations. We assessed the peak E velocity, mean pressure gradient (PG), and pressure half time (PHT) of the transprosthetic flow, the velocity-time integral (VTI) ratio of the PMV inflow to the left ventricular outflow, and the BSA-indexed effective orifice area (iEOA) of the PMV calculated with the continuity equation. Linear regression analysis revealed statistically significant correlations between all parameters of normally functioning PMVs and the PMV size z-scores (Pearson correlation coefficients: peak E velocity, -0.68; mean PG, -0.71; PHT, -0.82; VTI ratio, -0.76; iEOA, 0.79). Compared with the predictive values derived from the regression equations, the VTI ratio and iEOA exceeded ± 2 standard errors in both patients with obstructive PMVs.

CONCLUSION

To assess PMV function in children, Doppler-derived hemodynamic parameters should be compared with their predictive values based on relative PMV sizes. The deviation of the VTI ratio and iEOA from their predictive values may indicate prosthetic obstruction.

Transesophageal Echocardiographic Measurement of Cardiac Index by the Prosthetic Mitral Valve Method Is Not Similar to the Continuous Thermodilution Method Via a Pulmonary Artery Catheter

OBJECTIVE

To compare the agreement of cardiac index measurements between transesophageal echocardiography across the prosthetic mitral valve and the continuous thermodilution method through a pulmonary artery catheter (PAC-TD) in patients undergoing double-valve replacement.

DESIGN

Observational prospective study.

SETTING

University hospital.

PARTICIPANTS

Twenty-five patients undergoing double-valve replacement (12 men and 13 women, age 25-78 years, ASA III-IV, NYHA II-III, LVEF≥45%). Patients were grouped according to their prosthesis (mechanical prosthesis v bioprosthesis).

INTERVENTIONS

All patients underwent cardiac index assessment during double-valve replacement.

MEASUREMENTS AND MAIN RESULTS

Cardiac index across the prosthetic mitral valve was measured simultaneously using transesophageal echocardiography (CI(MV)) and PAC-TD (CI(PAC)) at 15, 30, 45, and 60 minutes after weaning from cardiopulmonary bypass, and at 0, 15, and 30 minutes after incision closure. A correlation was present between CI(MV) and CI(PAC) in both groups (mechanical prosthesis: r = 0.47, p<0.01; bioprosthesis: r = 0.60, p<0.01). In the mechanical prosthesis group, the bias between techniques (CI(PAC) v CI(MV)) was-0.5 L/min/m(2) (95% CI:-1.97 to 0.97), and error was 55%. In the bioprosthesis group, the bias between both techniques was-1.3 L/min/m(2) (95% CI:-3.1 to 0.5), and error was 56%.

CONCLUSIONS

A relatively weak correlation and lack of agreement between values of CI(PAC) and CI(MV) were observed in patients undergoing double-valve replacement. Therefore, transesophageal echocardiography might not be interchangeable with PAC-TD for measuring cardiac output or cardiac index. A regression equation is needed to correct the probable value of CI(PAC). CI(MV) might be useful as a quantitative or semi-quantitative cardiac output measurement.

Echocardiographic assessment of prosthetic valves

Echocardiographic evaluation of prosthetic valves is similar in many respects to evaluation of native valve disease. However, there are some important differences. First, there are several types of prosthetic valves with different fluid dynamics for each basic design and differing flow velocities for each valve size. Second, the mechanisms of valve dysfunction are somewhat different from those for native valve disease. Third, the technical aspects of imaging artificial devices, specifically the problem of acoustic shadowing, significantly affect the diagnostic approach when prosthetic valve dysfunction is suspected. Fourth, transcatheter aortic valve implantation (TAVI) has rapidly expanded in recent years. Echocardiography plays an essential role in identifying patients suitable for TAVI and providing intra-procedural monitoring, and is the modality for post-procedure follow-up. Both an understanding of the basic approach to echocardiographic evaluation and detailed knowledge of the specific flow dynamics for the size and type of prosthesis in an individual patient are needed for appropriate patient management.

Echocardiographic Assessment of Heart Valve Prostheses

Patients submitted to valve replacement with mechanical or biological prosthesis, may present symptoms related either to valvular malfunction or ventricular dysfunction from other causes. Because a clinical examination is not sufficient to evaluate a prosthetic valve, several diagnostic methods have been proposed to assess the functional status of a prosthetic valve. This review provides an overview of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. Compared to native valves, echocardiographic evaluation of prosthetic valves is certainly more complex, both for the examination and the interpretation. Echocardiography also allows discriminating between intra- and/or peri-prosthetic regurgitation, present in the majority of mechanical valves. Transthoracic echocardiography (TTE) requires different angles of the probe with unconventional views. Transesophageal echocardiography (TEE) is the method of choice in presence of technical difficulties. Three-dimensional (3D)-TEE seems to be superior to 2D-TEE, especially in the assessment of paravalvular leak regurgitation (PVL) that it provides improved localization and analysis of the PVL size and shape.

[Imaging following valve replacement]

Patients who undergo heart valve replacement require lifelong cardiac follow-up care. Although the primary pathology of the patient is treated by valve replacement, the risk of postoperative complications and structural failure of the implanted device requires regular check-ups where imaging plays an important role. Immediately after surgery reference values regarding prosthetic and cardiac function for further check-ups are obtained. Transthoracic and transesophageal echocardiography are the imaging modalities of choice for standard examination and follow-up due to their availability and low costs. However, when it comes to identification of complications they are often insufficient. Magnetic resonance imaging (MRI) and computed tomography (CT) play an increasingly important role as complementary modalities for the detection and monitoring of complications after valve replacement. The following article gives an overview of the current non-invasive examination methods and the use in the investigation of postoperative complications.

Comprehensive hemodynamic assessment of 368 normal St. Jude Medical mechanical mitral valve prostheses based on early postimplantation echocardiographic studies

BACKGROUND

Two-dimensional and Doppler-derived echocardiographic data on normal St. Jude Medical mechanical mitral valve prosthesis function have been reported but remain limited.

METHODS

Comprehensive retrospective two-dimensional and Doppler echocardiographic assessment of 368 normal St. Jude Medical mechanical mitral valve prostheses was performed early after implantation. The early postimplantation hemodynamic profiles of 98 patients were compared with profiles obtained by follow-up transthoracic echocardiography performed <13 months after implantation.

RESULTS

Using mean ± 2 SDs to define the normal distribution of values for Doppler-derived hemodynamic variables, the calculated normal ranges of values were as follows: mean gradient, 2 to 7 mm Hg; peak early mitral diastolic velocity (E velocity), 1.1 to 2.4 m/sec; time-velocity integral of the mitral valve prosthesis (TVIMVP) 20 to 50 cm; ratio of the TVIMVP to the time-velocity integral of the left ventricular outflow tract (TVILVOT), 0.9 to 2.5; pressure half-time, 35 to 99 msec; and effective orifice area, 1.12 to 3.24 cm(2). Patients with severe prosthesis-patient mismatch (ie, indexed effective orifice area ≤ 0.9 cm(2)/m(2)) had significantly higher mean gradients, E velocity, TVIMVP, and TVIMVP/TVILVOT. There was a trend for longer pressure half-times for patients with severe prosthesis-patient mismatch than for patients without severe prosthesis-patient mismatch, but none of these patients had pressure half-times > 130 msec. Among the 98 patients with follow-up transthoracic echocardiography <1 year after implantation, no significant differences were observed between early postimplantation findings and follow-up hemodynamic profiles.

CONCLUSIONS

This study establishes parameters (mean ± 2 SDs) defining the distribution of values for Doppler-derived hemodynamic data with normal St. Jude Medical mechanical mitral valve prostheses. Prostheses with hemodynamic values outside these parameters are likely dysfunctional; however, prosthesis dysfunction may be present even when hemodynamic values are within these ranges.

Percutaneous treatment of patients with heart diseases: selection, guidance and follow-up. A review

Aortic stenosis and mitral regurgitation, patent foramen ovale, interatrial septal defect, atrial fibrillation and perivalvular leak, are now amenable to percutaneous treatment. These percutaneous procedures require the use of Transthoracic (TTE), Transesophageal (TEE) and/or Intracardiac echocardiography (ICE). This paper provides an overview of the different percutaneous interventions, trying to provide a systematic and comprehensive approach for selection, guidance and follow-up of patients undergoing these procedures, illustrating the key role of 2D echocardiography.

Usefulness of live/real time three-dimensional transthoracic echocardiography in evaluation of prosthetic valve function

We studied 31 patients with prosthetic valves (PVs) using two-dimensional and three-dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides an incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE both leaflets of the St. Jude mechanical PV can be visualized simultaneously, thereby increasing the diagnostic confidence in excluding valvular abnormalities and overcoming the well-known limitations of 2DTTE in the examination of PVs, which heavily relies on Doppler. Three-dimensional transthorathic echocardiography provides a more comprehensive evaluation of PV regurgitation than 2DTTE with its ability to more precisely quantify PV regurgitation, in determining the mechanism causing regurgitation, and in localizing the regurgitant defect. Furthermore, 3DTTE is superior in identifying, quantifying, and localizing PV thrombi and vegetations, in addition to the unique feature of providing a look inside mass lesions by serial sectioning. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of PVs and that it provides incremental knowledge to the echocardiographer.

Identification and quantification of prosthetic mitral regurgitation by flow convergence method using transthoracic approach

The present case report illustrates the clinical applicability of the proximal isovelocity surface area (PISA) method in identifying, locating and assessing paravalvular prosthetic mitral regurgitation by transthoracic echocardiography.

Thrombosis of mechanical valve prosthesis in patient with recent Caesarean delivery

We present a case of a mechanical mitral valve thrombosis in a 37-year-old woman occurred 2 days after a Caesarean delivery. The patient stopped warfarin and initiated low-molecular-weight heparin 1 week before the programmed delivery. Subsequently the diagnosis of thrombosis, heparin infusion was started however unsuccessfully and eventually patient was referred for cardiac surgery.

Prosthetic heart valves: Types and echocardiographic evaluation

In the last five decades multiple different models of prosthetic valves have been developed. The purpose of this article is to provide a comprehensive source of information for the types and the echocardiographic evaluation of the prosthetic heart valves.

Doppler Echocardiography of 79 Normal CarboMedics Mitral Prostheses: A Comprehensive Assessment Including Time-Velocity Integral Ratio and Prosthesis Performance Index

Few reports have been published on the normal Doppler-derived echocardiographic data for CarboMedics (CarboMedics Inc., Austin, TX) prosthesis function in the mitral position. The purpose of this study was to provide a comprehensive Doppler echocardiographic assessment of normal CarboMedics mitral prosthesis function in a large number of patients. All of the important Doppler-derived hemodynamic variables reported to date were used. The pressure half-time was less than 130 msec in all patients, and nearly all patients (95%) had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2, regardless of prosthesis size or left ventricular function. No significant differences were found among different prosthesis sizes for effective orifice area, effective orifice area indexed to body surface area, or prosthesis performance index.

Doppler Echocardiography of Normal Starr-Edwards Mitral Prostheses: A Comprehensive Function Assessment Including Continuity Equation and Time-velocity Integral Ratio

The purpose of this study was to provide comprehensive Doppler echocardiographic assessment of the function of the normal Starr-Edwards mitral valve prosthesis using all the Doppler hemodynamic variables described to date, including the mitral valve prosthesis time-velocity integral (TVI)/left ventricular outflow tract TVI ratio and the prosthesis performance index. All patients had a peak early mitral diastolic velocity of no more than 2 m/s or a pressure half-time that was less than 130 milliseconds. All but one patient had either a peak early mitral diastolic velocity of no more than 2 m/s or a mitral valve prosthesis TVI/left ventricular outflow tract TVI ratio of less than 2.2, regardless of prosthesis size or left ventricular systolic function. There was a trend of decreasing prosthesis performance index with increasing prosthesis valve size that was not statistically significant, however.

Doppler echocardiography of 119 normal-functioning St Jude Medical mitral valve prostheses: A comprehensive assessment including time-velocity integral ratio and prosthesis performance index*

The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses.