Transesophageal echocardiographic (TEE) evaluation of prosthetic valves

Echocardiographic evaluation of prosthetic heart valves

The specific flow pattern and imaging features of prosthetic heart valves poses major challenges for the Doppler echocardiographic assessment of prosthetic valve structure and function. A comprehensive approach that integrates several semi-quantitative and quantitative parameters obtained from multiple views is key to appropriately detect and quantitate prosthetic valve dysfunction and complications. In patients with prosthetic valves, and particularly in those with mitral prostheses, transesophageal echocardiography is often required to confirm and/or complement information obtained by transthoracic echocardiography. Three-dimensional echocardiography may provide incremental information for the identification of the underlying etiology of prosthetic valve stenosis or regurgitation. Transcatheter aortic valve implantation has rapidly expanded in the past 10 years and paravalvular regurgitation is frequent following this procedure. Given that paravalvular regurgitant jets are often multiple, irregular, and eccentric, the grading of this type of regurgitation is particularly challenging and requires an integrative multiwindow, multiplane, multiparametric approach.

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.

Tissue engineering of autologous heart valves: a focused update

The prevalence of valvular heart disease is expected to increase in the coming decades, with an associated rise in valve-related surgeries. Current options for valve prostheses remain limited, essentially confined to mechanical or biological valves. Neither selection provides an optimal balance between structural integrity and associated morbidity. Mechanical valves offer exceptional durability coupled with a considerable risk of thrombogenesis. Conversely, a biological prosthesis affords freedom from anticoagulation, but with a truncated valve lifespan. Tissue-engineered heart valves have been touted as a solution to this dilemma, by offering an immunopriviledged prosthesis combined with resistance from degeneration and the potential to grow. Although the reality of commercially available tissue-engineered heart valves remains distant, this article will highlight the cellular and clinical advancements in recent years.

Real time three-dimensional transesophageal echocardiography: a novel approach for the assessment of prosthetic heart valves

OBJECTIVES

To explore our initial experience with real time three-dimensional transesophageal echocardiography (RT3DTEE) for the assessment of prosthetic valves (PV).

METHODS

The study included 40 patients (mean age 35 ± 8.5 years, 68% male) who underwent PV implant. Fifty PV (34 bioprosthetic and 16 mechanical) were evaluated using two-dimensional (2D)TEE and RT3DTEE to rule out PV dysfunction.

RESULTS

In all patients, RT3DTEE allowed good and simultaneous visualization of PV leaflets. Ten patients had normal functioning PV (5 in mitral, 3 in aortic, and 2 in tricuspid positions). Infective endocarditis was evident in 13 patients (20 PV) by repeated 2DTEE. RT3DTEE confirmed the 2DTEE diagnosis of endocarditis in same patients. Clear delineation of vegetations (size, site, and number) was obtained from RT3DTEE full volume while the vegetation attachment, consistency, mobility and its relation to valve structure were obtained using zoom 3D. Paraaortic abscesses size, site, extension, wall thickness of the abscess could be identified by RT3DTEE in 7 PV. Through cropping of the full-volume 3D images, the orifice of communication between the abscess cavity and aorta could be visualized well in en face view. Color full-volume allowed the detection of paravalvular regurgitation (size, location, direction, and extent) in 8 patients. In the 18 PV who underwent redo surgery, the intra-operative findings confirmed the RT3DTEE description of PV lesions.

CONCLUSION

Real time 3DTEE improved the anatomical and functional assessment of PV with better understanding of the underlying causes of PV dysfunction; hence, it could improve the management planning for such patients.

Recommendations for the management of patients after heart valve surgery

Approximately 50,000 valve replacement operations take place in Europe annually and almost as many valve repair procedures. Previous European guidelines on management of patients after valve surgery were last published in 1995 and were limited to recommendations about antithrombotic prophylaxis. American guidelines covering the broader topic of the investigation and treatment of patients with valve disease were published in 1998 but devoted relatively little space to post-surgical management. This document represents the consensus view of a committee drawn from three European Society of Cardiology (ESC) Working Groups (WG): the WG on Valvular Heart Disease, the WG on Thrombosis, and the WG on Rehabilitation and Exercise Physiology. In almost all areas of patient management after valve surgery, randomized trials and meta-analyses do not exist. Such randomized trials as do exist are very few in number, are narrowly focused with small numbers, have limited general applicability, and do not lend themselves to meta-analysis because of widely divergent methodologies and different patient characteristics. Recommendations are therefore almost entirely based on non-randomized studies and relevant basic science.

Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography

OBJECTIVE

To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency.

METHODS

47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole.

RESULTS

Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r = 0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm2 (r = 0.69) with worse correlation if a single imaging plane was used for measurements (r = 0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r = -0.66) with better correlation (r = -0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm2, with good correlation with angiography (r = 0.77 and r = 0.78, respectively).

CONCLUSIONS

TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet.

Assessing prosthetic mitral valve regurgitation by transoesophageal echo/Doppler

Transoesophageal echocardiography has greatly improved our ability to detect structural and regurgitant abnormalities associated with prosthetic mitral valves.

Intraoperative transesophageal echocardiographic assessment of acute prosthetic aortic valve regurgitation after mitral valve replacement: value of the deep transgastric long-axis view

The transesophageal echocardiographic assessment of prosthetic aortic valve function is made more difficult by the presence of a mechanical mitral valve prosthesis because echocardiographic views conventionally used to assess the aortic valve function are obscured by acoustic shadowing and artifacts. We report the use of intraoperative transesophageal echocardiography in a patient who developed severe prosthetic aortic valve regurgitation after implantation of a mechanical mitral valve, in whom conventional multiplane midesophageal views failed to reveal aortic regurgitation owing to acoustic shadowing and artifacts from the prosthetic mitral valve. We report the value of the deep transgastric long-axis view of the aortic valve that provided an unobstructed view of the left-ventricular outflow tract, and clearly demonstrated severe aortic regurgitation as a result of interference with the prosthetic aortic valve mechanism by the implanted mitral valve prosthesis. This case also emphasizes the importance of a comprehensive intraoperative transesophageal examination, including that of surrounding structures, to detect iatrogenic complications during mitral valve replacement.