**2.4.9 The pattern of 'billowing mitral valve'**

Is represented by the protrusion of the leaflet body into the left atrium cavity. As a rule, the coaptation point still remains into the left ventricular cavity (Figure 11). associated with mitral insufficiency, but it is important to indicate it to the surgical team.

Fig. 11. Billowing mitral valve. PSLAx view of transthoracic exam showing the protrusion of the posterior leaflet (P2 scallop) into the left atrial cavity. Often the mitral regurgitation may be absent or mild due to a pretty good coaptation, with the coaptation point still sited into the left ventricular cavity.

The Degenerative Mitral Valve Regurgitation:

exclusively on an automatic base.

establish its real practical value.

**2.6 Evaluation of mitral regurgitation** 

**length** 

From Geometrical Echocardiographic Concepts to Successful Surgical Repair 13

The transthoracic echocardiography is almost always sufficient to select the patient candidate to mitral valve repair or replacement. The preoperative transesophageal exam serves to refine the diagnosis, mainly in terms of pseudo-commissures, commissural prolapse, ruptured chordae etc. It is mandatory and the only tool used to assess the outcome of surgery in postoperative period. The transesophageal three-dimensional echocardiography is the best tool in assessing the commissural lesions pre and postoperatively. Thus, the echocardiography is an essential tool in the assessment of mechanism of mitral regurgitation and in choosing the right timing and the proper planning for surgical repair. The surgical strategy is tailored by the prolapsing score and the structural echocardiographic algorithm. The successful repair of mitral valve requires a

skilled team: an expert surgeon in valve repair and a dedicated echocardiographer.

**2.5 Rebuilding the geometry of the mitral valve: Triangle of coaptation and coaptation** 

Generally, the main target of the mitral valve repair is to achieve a minimum of 6mm of coaptation length. Initially, although not specified, this measure referred to the medial corresponding scallops A2-P2. As said before, the triangle of coaptation resembles an asymmetrical tent, meaning that the coaptation length varies among different regions of the valve. This fact was intuitive until recently, when studies were available in regard to the definition of the normal values of the coaptation for each valve region. Once threedimensional echocardiography became available, this type of analysis was possible

A recent study has defined the normal values of the coaptation length; these results indicated that the normal coaptation length in zone 1° (corresponding to the scallops A1/P1) is about 3.5mm; in zone 2° (scallops A2/P2) the coaptation length is round 6.2mm and finally in zone 3° (scallops A3/P3) the coaptation length seems to be slightly inferior to zone 1°, around 3.2mm. The authors also indicated that the contribution at coaptation of the anterior and posterior leaflets is not symmetrical. The anterior leaflet seems to have a major involvement compared to the posterior one in all the regions of the valve. This underlines

Another recent study has proposed a new measure for the coaptation length, namely the coaptation length index, which represents the ratio between the coaptation length and the end-systolic annular septal-lateral diameter (Shudo, 2010). Lately, echocardiographic indexation of all measures (generally to the BSA), has gained much consideration. From this perspective, the new index looks promising but needs further investigation in order to

Doppler echocardiography is the most common technique used for detection and evaluation of severity of valvular regurgitation. Several indexes have been used to assess the severity of regurgitation. The following paragraphs will make a brief description of the main indexes used in clinical practice, with their advantages and limitations. Surgery is addressed to patients with severe mitral degenerative regurgitation, and the quantification of the mitral insufficiency is a crucial point in the algorithm of decision. In the case of moderate mitral insufficiency, the surgery is considered only in patients with ischemic mitral regurgitation.

the importance of the functional reserve of the anterior leaflet (Gogoladze, 2011).

The final echo report contains coaptation height for each pair of scallops. The assessment of the triangle of coaptation, coaptation length and coaptation height. It represents an integrative scheme which is the synthesis of the various abnormalities found in different areas of the valve (Figure 1).

The mitral annular diameter must be assessed in parasternal long axis view. This measurement corresponds to the septo-marginal diameter of the valve, which is the most important diameter of mitral valve, because the mitral leaflets work in an anterior-posterior plane. The folding of the mitral leaflets depends on this diameter and not on the intercommissural diameter (Figure 12). Keep in mind that the TEE intraoperative measurement of the mitral annulus tends to underestimate it, due to intraoperative hypovolemic status and reduced overload.

Fig. 12. Correct measurement of the mitral valve annulus in PSLAX view. This diameter corresponds to the septo-marginal diameter of the valve (red diameter on the anatomical photo). The intercommissural diameter (the green diameter in the photo) has to be avoided in the algorithm of decision for surgical planning.

The left ventricular dimensions (as EDØ and EDVolume) and function (LVEF) completes the diagnostic echo algorithm. The severity of mitral insufficiency is mainly quantitatively assessed by calculating the regurgitating volume using the PISA method (proximal isovelocity surface area) and vena contracta. Naturally, all other cardiac structures are carefully described, focusing on associated valvular lesions, mainly on the tricuspide valve. A special attention is paid to the left atrial volume, which may predict atrial fibrillation when measuring around 100ml as volume, or 50mm in diameter (parasternal long axis view). The preoperative assessment should also be focused to identify the patients at high risk to develop postoperative systolic anterior motion: hypertrophic interventricular septum, small left ventricular cavity, hyper dynamic left ventricle (see also 2.6.1 Prepump examination).

The final report, using the Prolapsing Score and the structured anatomical analysis focused on mitral geometry, allows the surgeon to be aware of the complexity of the lesions and to develop a tailored surgical strategy of repair. In general, the surgical strategy aims to correct mitral regurgitation with a single orifice (achieving a coaptation length of at least 6mm) and, whenever possible, to rebuild the triangle of coaptation by using the PTFE GoreTex chordae and annuloplasty.

The final echo report contains coaptation height for each pair of scallops. The assessment of the triangle of coaptation, coaptation length and coaptation height. It represents an integrative scheme which is the synthesis of the various abnormalities found in different

The mitral annular diameter must be assessed in parasternal long axis view. This measurement corresponds to the septo-marginal diameter of the valve, which is the most important diameter of mitral valve, because the mitral leaflets work in an anterior-posterior plane. The folding of the mitral leaflets depends on this diameter and not on the intercommissural diameter (Figure 12). Keep in mind that the TEE intraoperative measurement of the mitral annulus tends to underestimate it, due to intraoperative

Fig. 12. Correct measurement of the mitral valve annulus in PSLAX view. This diameter corresponds to the septo-marginal diameter of the valve (red diameter on the anatomical photo). The intercommissural diameter (the green diameter in the photo) has to be avoided

The left ventricular dimensions (as EDØ and EDVolume) and function (LVEF) completes the diagnostic echo algorithm. The severity of mitral insufficiency is mainly quantitatively assessed by calculating the regurgitating volume using the PISA method (proximal isovelocity surface area) and vena contracta. Naturally, all other cardiac structures are carefully described, focusing on associated valvular lesions, mainly on the tricuspide valve. A special attention is paid to the left atrial volume, which may predict atrial fibrillation when measuring around 100ml as volume, or 50mm in diameter (parasternal long axis view). The preoperative assessment should also be focused to identify the patients at high risk to develop postoperative systolic anterior motion: hypertrophic interventricular septum, small left ventricular cavity, hyper dynamic left ventricle (see also 2.6.1 Prepump

The final report, using the Prolapsing Score and the structured anatomical analysis focused on mitral geometry, allows the surgeon to be aware of the complexity of the lesions and to develop a tailored surgical strategy of repair. In general, the surgical strategy aims to correct mitral regurgitation with a single orifice (achieving a coaptation length of at least 6mm) and, whenever possible, to rebuild the triangle of coaptation by using the PTFE GoreTex chordae

areas of the valve (Figure 1).

hypovolemic status and reduced overload.

in the algorithm of decision for surgical planning.

examination).

and annuloplasty.

The transthoracic echocardiography is almost always sufficient to select the patient candidate to mitral valve repair or replacement. The preoperative transesophageal exam serves to refine the diagnosis, mainly in terms of pseudo-commissures, commissural prolapse, ruptured chordae etc. It is mandatory and the only tool used to assess the outcome of surgery in postoperative period. The transesophageal three-dimensional echocardiography is the best tool in assessing the commissural lesions pre and postoperatively. Thus, the echocardiography is an essential tool in the assessment of mechanism of mitral regurgitation and in choosing the right timing and the proper planning for surgical repair. The surgical strategy is tailored by the prolapsing score and the structural echocardiographic algorithm. The successful repair of mitral valve requires a skilled team: an expert surgeon in valve repair and a dedicated echocardiographer.

#### **2.5 Rebuilding the geometry of the mitral valve: Triangle of coaptation and coaptation length**

Generally, the main target of the mitral valve repair is to achieve a minimum of 6mm of coaptation length. Initially, although not specified, this measure referred to the medial corresponding scallops A2-P2. As said before, the triangle of coaptation resembles an asymmetrical tent, meaning that the coaptation length varies among different regions of the valve. This fact was intuitive until recently, when studies were available in regard to the definition of the normal values of the coaptation for each valve region. Once threedimensional echocardiography became available, this type of analysis was possible exclusively on an automatic base.

A recent study has defined the normal values of the coaptation length; these results indicated that the normal coaptation length in zone 1° (corresponding to the scallops A1/P1) is about 3.5mm; in zone 2° (scallops A2/P2) the coaptation length is round 6.2mm and finally in zone 3° (scallops A3/P3) the coaptation length seems to be slightly inferior to zone 1°, around 3.2mm. The authors also indicated that the contribution at coaptation of the anterior and posterior leaflets is not symmetrical. The anterior leaflet seems to have a major involvement compared to the posterior one in all the regions of the valve. This underlines the importance of the functional reserve of the anterior leaflet (Gogoladze, 2011).

Another recent study has proposed a new measure for the coaptation length, namely the coaptation length index, which represents the ratio between the coaptation length and the end-systolic annular septal-lateral diameter (Shudo, 2010). Lately, echocardiographic indexation of all measures (generally to the BSA), has gained much consideration. From this perspective, the new index looks promising but needs further investigation in order to establish its real practical value.

#### **2.6 Evaluation of mitral regurgitation**

Doppler echocardiography is the most common technique used for detection and evaluation of severity of valvular regurgitation. Several indexes have been used to assess the severity of regurgitation. The following paragraphs will make a brief description of the main indexes used in clinical practice, with their advantages and limitations. Surgery is addressed to patients with severe mitral degenerative regurgitation, and the quantification of the mitral insufficiency is a crucial point in the algorithm of decision. In the case of moderate mitral insufficiency, the surgery is considered only in patients with ischemic mitral regurgitation.

The Degenerative Mitral Valve Regurgitation:

reduced correlation with angiography.

of the regurgitant orifice (Otto, 2002).

**2.6.3 Vena contracta** 

criteria used to send the patients in the operating room.

**2.6.2 Color flow mapping** 

From Geometrical Echocardiographic Concepts to Successful Surgical Repair 15

Mitral regurgitation has been most frequently evaluated through the Colour Doppler method. As all the guidelines use echocardiographic criteria to indicate surgery in valvular patients, the echocardiographer must be aware of the drawbacks of the echocardiographic

For example, the maximal jet area correlates well with the semi quantitative angiographic grade of severity. However, only limited correlation is observed with quantitative measures of regurgitant volume and fraction. In addition, maximal jet area is not predictive of hemodynamic abnormalities, such as an elevated pulmonary capillary wedge pressure or reduced forward stroke volume. The regurgitant jet geometry, the physiologic variability, and the instrument settings are presumably some of the factors that may explain this

Given the three-dimensional shape of the regurgitant flow, in all scanning sections, the regurgitant jet area will depend on the geometry and direction of the jet. Colour flow Doppler mapping of free regurgitant jets that are unbounded by surrounding structures may lead to overestimation of severity due to entrainment of adjacent fluid by the highvelocity jet. In contrast, the area of an eccentric jet is only 40% of the area of a free jet with the same regurgitant fraction. Eccentric jets are influenced by adjacent constraining surfaces, so that area measurements correlate poorly with regurgitant volume. It is also important to remember that the colour flow map of a regurgitant jet represents the spatial distribution of velocities and is not a direct measure of volume flow rate. Although colour Doppler jet area increases with regurgitant volume, this relationship is not linear because it is highly influenced by driving pressure, compliance of the receiving chamber, and the size and shape

It is one of the preferred echocardiographic indexes for its efficacy and its simplicity. The vena contracta is the narrowest portion of a jet that occurs at or just downstream from the orifice (Baumgartner, 1991). It is characterized by high velocity, laminar flow and is slightly

The cross-sectional area of the vena contracta represents a measure of the effective regurgitant orifice area (EROA), which is the narrowest area of the actual flow. The size of the vena contracta is independent of the flow rate and driving pressure for a fixed orifice. However, if the regurgitant orifice is dynamic, the vena contracta may change with hemodynamics or during the cardiac cycle. Comprised of high velocities, the vena contracta is considerably less sensitive to technical factors such as PRF compared to the jet in the receiving chamber. To specifically image the vena contracta, it is often necessary to angulate the transducer out of the normal echocardiographic imaging planes, such that the area of proximal flow acceleration, the vena contracta, and the downstream expansion of the jet can be distinguished. It is preferable to use a zoom mode to optimize visualization of the vena contracta and facilitate its measurement. The Colour flow sector should also be as narrow as possible, with the minimal depth, so as to maximize lateral and temporal resolution.

smaller than the anatomic regurgitation orifice due to boundary effects.

#### **2.6.1 Proximal isovelocity surface area (PISA) or flow convergence**

In most patients, PISA was the method of choice for the quantification of mitral regurgitation. As already extensively described, the PISA method is derived from the hydrodynamic principle stating that, as blood approaches a regurgitant orifice, its velocity increases, forming concentric roughly hemispheric shells of increasing velocity and decreasing surface area.

Colour flow mapping offers the ability to visualise one of these hemispheres that corresponds to the Nyquist limit of the instrument. If a Nyquist limit can be chosen at which the flow convergence becomes hemispheric in shape, the flow rate through the regurgitant orifice (ml/s) may be calculated as the product of the surface area of the hemisphere and the aliasing velocity. Assuming that the maximal PISA radius occurs at the time of peak regurgitant flow and peak regurgitant velocity, the maximal EROA is derived. The regurgitant volume can be estimated as EROA multiplied by the velocity time integral of the regurgitant jet. Since the PISA calculation provides an instantaneous peak flow rate, EROA by this approach is the maximal EROA and may be slightly larger than EROA calculated by other methods (Bargiggia, 1991).

As indicated by the guidelines of evaluation of valve regurgitation, the measurement of PISA by Colour Flow Mapping was done by adjustment of the aliasing velocity until a welldefined hemisphere was apparent. This was generally done by shifting the baseline towards the direction of flow, by lowering the Nyquist limit, or both. This has been shown to improve the reliability of the measurement (Zoghbi, 2003).

Despite the fact that it became the preferred method for evaluation of mitral regurgitation, the PISA method is far from being perfect. As with any other technique, limitations exist, e.g.: it is more accurate for central jets than for eccentric jets and for regurgitation with a circular orifice. If the image resolution allows a good visualisation of the flow convergence, and a Nyquist limit can be chosen in order to obtain a hemispheric shape of the convergence, it is easy to identify the aliasing line of the hemisphere. However, it can be difficult to judge the precise location of the orifice and the flow convergence shape. Any error introduced is then squared, which can markedly affect the resulting flow rate and EROA. Attention should be paid to remain as parallel as possible with the Doppler beam. In every day practice, the main error in grading the mitral insufficiency occurs with the eccentric jets. Fig 13 (A,B).

Fig. 13. (A,B). Simultaneous transthoracic PSLAX view and apical three chamber view showing an eccentric regurgitant jet in anterior mitral prolapse.

### **2.6.2 Color flow mapping**

14 Echocardiography – In Specific Diseases

In most patients, PISA was the method of choice for the quantification of mitral regurgitation. As already extensively described, the PISA method is derived from the hydrodynamic principle stating that, as blood approaches a regurgitant orifice, its velocity increases, forming concentric roughly hemispheric shells of increasing velocity and

Colour flow mapping offers the ability to visualise one of these hemispheres that corresponds to the Nyquist limit of the instrument. If a Nyquist limit can be chosen at which the flow convergence becomes hemispheric in shape, the flow rate through the regurgitant orifice (ml/s) may be calculated as the product of the surface area of the hemisphere and the aliasing velocity. Assuming that the maximal PISA radius occurs at the time of peak regurgitant flow and peak regurgitant velocity, the maximal EROA is derived. The regurgitant volume can be estimated as EROA multiplied by the velocity time integral of the regurgitant jet. Since the PISA calculation provides an instantaneous peak flow rate, EROA by this approach is the maximal EROA and may be slightly larger than EROA calculated by

As indicated by the guidelines of evaluation of valve regurgitation, the measurement of PISA by Colour Flow Mapping was done by adjustment of the aliasing velocity until a welldefined hemisphere was apparent. This was generally done by shifting the baseline towards the direction of flow, by lowering the Nyquist limit, or both. This has been shown to

Despite the fact that it became the preferred method for evaluation of mitral regurgitation, the PISA method is far from being perfect. As with any other technique, limitations exist, e.g.: it is more accurate for central jets than for eccentric jets and for regurgitation with a circular orifice. If the image resolution allows a good visualisation of the flow convergence, and a Nyquist limit can be chosen in order to obtain a hemispheric shape of the convergence, it is easy to identify the aliasing line of the hemisphere. However, it can be difficult to judge the precise location of the orifice and the flow convergence shape. Any error introduced is then squared, which can markedly affect the resulting flow rate and EROA. Attention should be paid to remain as parallel as possible with the Doppler beam. In every day practice, the main error in

**2.6.1 Proximal isovelocity surface area (PISA) or flow convergence** 

decreasing surface area.

other methods (Bargiggia, 1991).

improve the reliability of the measurement (Zoghbi, 2003).

grading the mitral insufficiency occurs with the eccentric jets. Fig 13 (A,B).

Fig. 13. (A,B). Simultaneous transthoracic PSLAX view and apical three chamber view

showing an eccentric regurgitant jet in anterior mitral prolapse.

Mitral regurgitation has been most frequently evaluated through the Colour Doppler method. As all the guidelines use echocardiographic criteria to indicate surgery in valvular patients, the echocardiographer must be aware of the drawbacks of the echocardiographic criteria used to send the patients in the operating room.

For example, the maximal jet area correlates well with the semi quantitative angiographic grade of severity. However, only limited correlation is observed with quantitative measures of regurgitant volume and fraction. In addition, maximal jet area is not predictive of hemodynamic abnormalities, such as an elevated pulmonary capillary wedge pressure or reduced forward stroke volume. The regurgitant jet geometry, the physiologic variability, and the instrument settings are presumably some of the factors that may explain this reduced correlation with angiography.

Given the three-dimensional shape of the regurgitant flow, in all scanning sections, the regurgitant jet area will depend on the geometry and direction of the jet. Colour flow Doppler mapping of free regurgitant jets that are unbounded by surrounding structures may lead to overestimation of severity due to entrainment of adjacent fluid by the highvelocity jet. In contrast, the area of an eccentric jet is only 40% of the area of a free jet with the same regurgitant fraction. Eccentric jets are influenced by adjacent constraining surfaces, so that area measurements correlate poorly with regurgitant volume. It is also important to remember that the colour flow map of a regurgitant jet represents the spatial distribution of velocities and is not a direct measure of volume flow rate. Although colour Doppler jet area increases with regurgitant volume, this relationship is not linear because it is highly influenced by driving pressure, compliance of the receiving chamber, and the size and shape of the regurgitant orifice (Otto, 2002).
