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The title should be at least 4 characters long. Your display name should be at least 2 characters long. At Kobo, we try to ensure that published reviews do not contain rude or profane language, spoilers, or any of our reviewer's personal information. Alternatively, RT3DE could complement conventional 2D studies with a specific focus on the structures of interest.. Although RT3DE has succeeded in eliminating some of the limitations that prevented the application of other 3D techniques in clinical practice, significant limitations remain.
The technique relies on image quality and there is a long learning curve to optimal image acquisition. Compared with conventional 2DE, RT3DE suffers from low spatial resolution which, for example, prevents automatic endocardial border detection for volume quantification.. The lower frame rate can also be a significant limitation when quantifying regurgitant flow. Full volume imaging acquires the data over heartbeats and thus is prone to ECG-related and respiratory motion artifacts.
Finally, real-time "live" imaging, although it requires no reconstruction, is limited by the small volume acquired.. Three-dimensional echocardiography is the diagnostic technique that has contributed most to our knowledge of MV anatomy and function. Through in vitro studies and 3DE studies conducted in animal models, changes that occur in mitral and ventricular geometry following myocardial infarction, thereby giving rise to mitral regurgitation MR , have been demonstrated.
Figure 4. Mechanism of functional mitral regurgitation. Reduction of the force of closure of mitral valve during systole orange arrow. Increase in the distance of tethering due to the apical displacement of the papillary muscles blue arrow.. There is an imbalance between the closing forces on the mitral valve during systole. On the other hand, apical and lateral papillary muscle PM displacement, secondary to adverse left ventricular remodeling, causes apically-directed traction of the mitral leaflets, reduces the degree of MV coaptation, and results in MR.
Moreover, the mitral annulus usually dilates to a greater degree. Using 3DE, we can analyze the components of the mitral apparatus in detail, thereby understanding normal functional anatomy and the changes that occur in FMR.. Three-dimensional echocardiography has demonstrated that the mitral annulus is saddle-shaped. The lowest points are the two mitral commissures Figure 5A. In healthy individuals, this shape is most marked during mid-systole when the mitral annulus attains its smallest area. Figure 5. Three-dimensional image of the mitral annulus. A: normal, saddle-shaped, mitral annulus; the more cranial regions correspond to the anterior and posterior regions of the annulus.
B: flattened mitral annulus in patient with functional mitral regurgitation.. In patients with FMR, dilatation and flattening of the mitral annulus occur simultaneously Figure 5B. Although the annulus dilates as a whole, the anteroposterior diameter dilates relatively more and thus the principal advantage of TERT3DE over 2D transesophageal echocardiography is that it enables us to see the MV from any angle and map the mitral valvules from a single image without the need for mentally reconstruction. Alternatively, RT3DE could the shape of the annulus becomes more circular.
This is most likely caused by the asymmetric remodeling seen in the ischemic variant. Similarly, mitral annular remodeling seems to differ depending on infarct location. In infarctions prior to dilatation and mitral annulus flattening, remodeling is greater than in inferior infarctions. In patients with FMR, this displacement is reduced, most notably in the posterior region.. Salgo et al 19 confirmed that the MV's saddle shape reduces the tension that its leaflets are subject to, as compared to a mitral valve with a more flattened annulus.
The curvature contributes to the mechanism that avoids the appearance of MI and reflects the annulus' capacity to contract during systole.. With 3DE, the capability to trace the mitral leaflets and measure their area using specialized computer software exists. In addition, the tenting volume the volume in the space between the mitral annulus and the "tented" mitral leaflets can easily be measured thus giving an idea of the amount of tethering on the leaflets.
In normal individuals, during mitral valve closure, the leaflets coapt at the level of the mitral annulus and the portion of the anterior leaflet closest to the aortic root protrudes slightly towards the left atrium. In FMR, the coaptation area is displaced apically due to leaflet traction by the papillary muscles. To date, 2DE has been used exclusively to calculate the mitral valve tenting area as an estimate of how left ventricular remodeling and geometrical changes have affected mitral annular geometry 20 Figure 6A.
However, recent studies have shown the asymmetry of this tenting area21 and the existence of patterns that differ with the etiology of FMR, 22 making single plane studies less than optimal. In contrast, 3DE enables the measurement of tenting volume, the maximal diameter between the mitral annulus and mitral leaflet surface, and the visualization of leaflet deformation from any angle Figures 6B and C.. Figure 6. A: 2-dimensional image in apical plane, measuring the area of tenting.
A 3-dimensional reconstruction of the mitral valvules in green can be made using manual tracing with a minimum of 6 2-dimensional planes. Once traced, the volume comprendido between the annulus and the mitral valvules volume of tenting is calculated automatically. C: 3-dimensional reconstruction of the volume of tenting green together with the left ventricle red and mitral annulus blue..
Subvalvular Apparatus and the Left Ventricle. Mitral leaflet traction due to papillary muscle displacement appears to be the principal causal mechanism of FMR. The amount of left ventricular remodeling differs depending on the insult and so too does the degree of PM displacement. In patients with idiopathic dilated cardiomyopathy, global ventricular remodeling occurs with resultant displacement of both PMs.
Similar remodeling may occur in patients with anterior myocardial infarction and chronic MR. In both examples, the ventricle progressively dilates and takes on a more spherical shape. In contrast, in patients with FMR due to inferior infarction, localized ventricular remodeling is more common with resultant posteromedial PM displacement, producing MR through isolateral hemi-valvule traction.
Changes in the geometry of the mitral annulus and left ventricle are also accompanied by changes in the spatial relation between the components of the MV. To date, the principal parameter measured by 3DE has been tethering distance, ie the distance between the trigones and the head of the papillary muscles. Most studies have measured the distance between the medial trigone and the head of the posteromedial PM, and have found good correlation with the degree of distortion of MV geometry. Currently, quantification of MR based on the proximal isovelocity surface area PISA is one of the more frequently used and validated methods.
With 3D color Doppler, it has been proven that this geometric assumption is not always fulfilled, 28,29 and that the measure regurgitant orifice may be underestimated. Matsumura et al 30 compared regurgitant orifice geometry in patients with mitral valve prolapse MVP and patients with FMR. Consequently, 3D color Doppler seems an appropriate technique to decide whether to use the conventional PISA method or assume a semi-elliptical shape for the mathematical calculation of regurgitant orifice area Figure Figure 7.
Simultaneous view of 3 electrocardiographic slices obtained from a full-volume image. The planes need to be reoriented to find the one that includes the regurgitation flow in its entirety. The coronal A and sagittal B slices enable us to measure the height of the semi-ellipse to calculate the regurgitant volume by the PISA method. In the transverse slice C , we can see the base of the semi-ellipse with one larger and one smaller diameter.
D: representation of the shape of the proximal isovelocity surface area.. Since RT3DE was incorporated into clinical practice, one of its principle applications has been mitral valve pathology, in particular the quantification of valvular area and analysis of functional MV anatomy, both in Carpentier type II lesions e. The diagnosis and determination of the severity of mitral stenosis is based on 2DE and Doppler techniques.
However, it is accepted that these methods are influenced by hemodynamic status heart rate, cardiac rhythm, cardiac output , the compliance of the ventricle, and the presence of other associated valvular lesions. Planimetered mitral area methods are not affected by hemodynamic changes so they are widely used today. RT3DE is a rapid, precise technique for determining the valvular orifice area, as it facilitates the orientation of any slice plane to locate the minimal MV area.
Thus, it eliminates one of the principle limitations of 2DE in determining mitral valve area by planimetry. Several studies have compared 3DE with traditional methods of calculating MV area. Moreover, with RT3DE there is less inter- and intra-observer variation when calculating mitral valve area. Inter-observer variation in calculating Wilkins' score to predict success in percutaneous valvuloplasty is also less with RT3DE.
Currently, traditional methods together with RT3DE could probably be considered the best option when studying mitral stenosis.. In one of the first 3DE studies, Levine et al 14 confirmed that due to the saddle-shape of the mitral annulus, diagnosis of MVP by 2DE may be erroneous because apparent leaflet displacement toward the left atrium does not occur. Using 3DE, the prolapsed segment appears convex in shape when seen from the left atrium and concave when seen from the left ventricle.
Using the 2D plane view sagittal, coronal, transverse we can choose the most appropriate plane in which to study the motion of each scallop.. Probably due to its greater size, the anterior leaflet was more easily seen, both in the parasternal and apical views.
The posterior leaflet was better identified from the parasternal view. Rapid, single-image acquisition with a 3D transesophageal probe enables the evaluation of each mitral scallop from any angle without the necessity of mental reconstruction of different echocardiographic slices. Implications for Heart Surgery. Reductive mitral annuloplasty continues to be the surgical treatment of choice in patients with FMR. Prior to valve surgery a detailed study of the anatomy and function of the mitral valve should be conducted. Conventional 2DE is severely limited in studying the 3-dimensional structure of the MV with precision, especially in the context of FMR.
Real-time 3DE permits its visualization from any angle, including that of the surgeon's at the operating table Figure 8. With these clear advantages, TERT3DE is becoming one of the principle tools for the surgeon both in planning and monitoring these types of surgical interventions.. Figure 8. The mitral valve is viewed from the atrium with the aorta at 11 o'clock the surgeon's view. The posterior mitral valvule PMV presents a prolapse at the level of the medial scallop red arrow.
AV indicates aortic valve; AMV, anterior mitral valvule.. New prosthetic mitral annuloplasty devices are being designed to attempt to recover the original shape of the mitral annulus and permit annular contraction and displacement as far as possible. In this new context, 3DE may be used for a detailed evaluation of the geometry of the annulus and possibly help select the most appropriate prosthesis. In addition, similar studies can be conducted post-implantation to evaluate the changes in annular geometry.. Due to the complex pathogenic mechanism of FMR, it is important to conduct a detailed study of mitral and ventricular geometry.
To achieve reproducible measures, it is necessary to identify the imaging plane that defines each of the cardiac structures. This limitation is overcome with 3DE Figure 9. With the development of new, user-friendly, 3D-images analysis software, the time needed to measure mitral geometry is no more than 5 minutes. The precise mechanism of MR can now be elucidated using novel 3DE imaging techniques. The above-mentioned parameters that can now be measured with 3DE will surely help improve results of mitral repair Table Using 3DE, we obtain more exact, reproducible measurements of the mitral geometry.
The visualization of two simultaneous slices, A sagittal and C transverse , enables us to see the error we make when we try to measure the intercommissure diameter of the mitral annulus points. Reorienting these two planes, we obtain a sagittal slice B that runs through both mitral commissures D. Ant indicates anterior; LV, left ventricle; RV, right ventricle.. So, visualization of the annulus and mitral valvules in their totality, together with analysis of subvalvular apparatus, would reveal the precise MI mechanism to the surgeon together with the degree of mitral and ventricular geometry distortion in each patient.
This would facilitate individualized repair surgery planning and improve results.. In recent years, various devices and techniques used in experimental and clinical trials have demonstrated MR reduction and reverse left ventricular remodeling.
Using 3DE, Levine et al have shown that repositioning the posteroinferior PM with an epicardial patch reduces MR and tethering distance. Cardiac resynchronization therapy CRT is a therapeutic alternative in patients with advanced heart failure that is refractory to medical treatment 61,62 and has been shown to reduce the degree of FMR. Preliminary results show that, in patients treated with CRT, a significant reduction in ventricular volumes occurs together with favorable changes in the spatial relation between the MV components and thereby a significant reduction in tenting volume.
The application of echocardiography in the cardiac catheterization laboratory has facilitated certain interventions and has allowed the timely detection of procedural complications. In recent years we have witnessed the incorporation of transesophageal and intracardiac 2DE in the catheterization laboratory for guidance of percutaneous procedures.
Given the additional advantages of TERT3DE over existing echocardiographic modalities, the time is right for its use in the guidance of similar procedures. As mentioned earlier, RT3DE can also be especially useful in determining mitral valve area in patients with mitral stenosis and it could reliably be applied in percutaneous mitral valvuloplasty procedures. This is especially interesting if we consider how imprecise immediate, conventional non-invasive post-procedural techniques are.
Three-dimensional visualization of the entire mitral annulus prosthesis in patients with periprosthetic leaks obviates the mental reconstruction necessary to localize their origin and, consequently, improves diagnostic precision. Although there is minimal scientific evidence to support it, the application of RT3DE may provide a great advance in the guidance of percutaneous closure procedures for periprosthetic leaks.
Moreover, it will be able to guide MV procedures such as the Alfieri percutaneous repair technique 67 or mitral annuloplasty ring implantation via the coronary sinus.. The application of 3DE to the study of the MV contributes unique information about its functional anatomy that can be of great use in improving the knowledge and treatment of MV pathologies.
Specifically, its application in the field of mitral repair and in percutaneous interventions can contribute a substantial therapeutic advance in the coming years.. Correspondence: Dr J. Home Articles in press Current Issue Archive. ISSN: Previous article Next article.
Issue 2. Pages February More article options. Three-Dimensional Echocardiography. New Possibilities in Mitral Valve Assessment. Download PDF. This item has received. Article information. Recent developments in three-dimensional echocardiography have made it possible to obtain images in real time, without the need for off-line reconstruction. These developments have enabled the technique to become an important tool for both research and daily clinical practice.
A substantial proportion of the studies carried out using three-dimensional echocardiography have focused on the mitral valve, the pathophysiology of mitral valve disease and, in particular, functional mitral regurgitation. The aims of this article were to review the contribution of three-dimensional echocardiography to understand the functional anatomy of the mitral valve and to summarize the resulting clinical applications and therapeutic implications..
Three-dimensional echocardiography. Palabras clave:. The objective of this article is to review the contribution of 3DE to our knowledge of MV functional anatomy, the clinical applications of 3DE and its therapeutic implications. However, due to the lengthy image-processing time required, its use was limited clinically to a few echocardiography laboratories and to the research arena.
These new advances have allowed the application of 3DE to daily clinical practice. Real-time imaging makes synchronization with the electrocardiogram unnecessary, but the acquired volume is narrower. A system for ultrasonically imaging the human heart in three dimensions.. Comput Biomed Res, 7 , pp. Tomographic three-dimensional echocardiographic determination of chamber size and systolic function in patients with left ventricular aneurysm: comparison to magnetic resonance imaging, cineventriculography, and two-dimensional echocardiography..
Circulation, 96 , pp. Rapid online quantification of left ventricular volume from real-time three-dimensional echocardiographic data.. Eur Heart J, 27 , pp.
Comparison of transthoracic three dimensional echocardiography with magnetic resonance imaging in the assessment of right ventricular volume and mass.. Heart, 78 , pp. Real-time, three-dimensional echocardiography: feasibility of dynamic right ventricular volume measurement with saline contrast.. Am Heart J, , pp. Three-dimensional color Doppler: a clinical study in patients with mitral regurgitation.. J Am Coll Cardiol, 33 , pp. Three-dimensional color Doppler: a new approach for quantitative assessment of mitral regurgitant jets..