**2.7.1 Prepump examination**

During the intraoperative transesophageal echocardiography, the evaluation of the severity of mitral regurgitation should be performed following the same steps and methodology as in all other echocardiographic examinations. It was observed that the degree of mitral regurgitation assessed by TEE in the operating theatre appears less severe in respect to the transthoracic exam. The team (anaesthesiologist, cardiologist and surgeon) has to be aware of the complexity of the changes induced by the general anaesthesia and the opening of the thorax and pericardial cavity. It also needs to be taken into account the loading condition of the heart, in term of the preload and afterload. Therefore, prepump TEE examination should not be used to assess the severity of the regurgitation, but mainly to assess its mechanism and the valve anatomy.

Important items on the preoperative echocardiographic check-list are the valve anatomy and the analysis of the coaptation: Does it exists? Is it absent or only reduced? In what valve sector is the coaptation missing or reduced? Why? Is there a prolapsed valve or flail? How much does each segment prolapse in regard to the mitral annular plane?

The answer to these final questions is essential for the surgeon who needs to perform a mitral valve repair. The correct evaluation of the entity of prolapse in tele-systole and in all segments may assist the surgeon in the decision of the length and position of the Gore-Tex neochordae they might need to use in order to correct the prolapse. In the operating theatre, the echocardiographer should measure the distance between the free border of the prolapsing scallop and the mitral annulus plane or the free border of the non-prolapsing scallop (Fig 14). This may be of great importance in measuring the length of the artificial chordae, but the experience of the surgeon remains the most important factor that will determine the final result.

Because of the small values of the width of the vena contracta (usually <1cm), small errors in its measurement may lead to a large percentage error and misclassification of the severity of regurgitation. Therefore, it is very important to acquire accurate primary data and

The vena contracta method for assessing mitral regurgitation by colour Doppler echocardiography overestimates true mitral regurgitant orifice, it is markedly influenced by flow rate and the ultrasound system that is used. However, a diameter of a vena contracta over 8mm has a very good sensitivity and specificity for discriminating severe from non-severe mitral regurgitation (Zoghbi, 2003). The estimation of the diameter of the vena contracta is considered to have a good reproducibility of 10-15% (Margulescu,

The intraoperative echocardiography may be performed using the transesophageal or sometimes the epicardial method. In our practice we used almost exclusively the former. The epicardial approach may be used in paediatric cardiac surgery, when the adult TEE

During the intraoperative transesophageal echocardiography, the evaluation of the severity of mitral regurgitation should be performed following the same steps and methodology as in all other echocardiographic examinations. It was observed that the degree of mitral regurgitation assessed by TEE in the operating theatre appears less severe in respect to the transthoracic exam. The team (anaesthesiologist, cardiologist and surgeon) has to be aware of the complexity of the changes induced by the general anaesthesia and the opening of the thorax and pericardial cavity. It also needs to be taken into account the loading condition of the heart, in term of the preload and afterload. Therefore, prepump TEE examination should not be used to assess the severity of the regurgitation, but mainly to assess its mechanism

Important items on the preoperative echocardiographic check-list are the valve anatomy and the analysis of the coaptation: Does it exists? Is it absent or only reduced? In what valve sector is the coaptation missing or reduced? Why? Is there a prolapsed valve or flail? How

The answer to these final questions is essential for the surgeon who needs to perform a mitral valve repair. The correct evaluation of the entity of prolapse in tele-systole and in all segments may assist the surgeon in the decision of the length and position of the Gore-Tex neochordae they might need to use in order to correct the prolapse. In the operating theatre, the echocardiographer should measure the distance between the free border of the prolapsing scallop and the mitral annulus plane or the free border of the non-prolapsing scallop (Fig 14). This may be of great importance in measuring the length of the artificial chordae, but the experience of the surgeon remains the most important factor that will

much does each segment prolapse in regard to the mitral annular plane?

measurement (Zoghbi, 2003).

**2.7.1 Prepump examination** 

and the valve anatomy.

determine the final result.

**2.7 Intraoperative assessment of mitral regurgitation** 

probe is too large and the paediatric TEE probe is not available.

Brickner).

Fig. 14. (A,B,C). Intraoperative echocardiographic measurements showing prolapsed with flail of the posterior mitral leaflet (14A). The red line indicates the prolapsing plane; the green indicates the targeted coaptation plane (14B). Measuring the distance between the targeted position of the P2 scallop plane and the tip of the papillary muscle helps the surgeon decide the length of the neochordae (14C).

The preoperative echocardiographic examination must be performed under normal or near normal loading conditions. If hypovolemia were present, not only the severity of mitral regurgitation might be underestimated, as stated before, but also a false prolapse of various segments might erroneously be described. Often, a false prolapse may be encountered at the level of the anterior mitral leaflet (scallops A2 and A3) when, in fact, the lesion, usually flail, eversion or extreme prolapse, is typically located on the posterior leaflet. In order to avoid this risk, the echocardiographer should bear in mind the diagnosis of the preoperative transthoracic examination and carefully compare it to his own findings. One should not forget that most of the times the transesophageal examination confirms most of the elements from the transthoracic exam. By using the new harmonics echocardiographic machines, approximately 2/3 of the lesions found in transthoracic examination will be confirmed by TEE exam. The mitral annulus might also be underestimated when hypovolemia is present. This is the case in the operating room when the prepump exam is performed. In our experience the transthoracic measurement of the mitral annulus should always be taken into account when the surgical strategy is discussed with the surgeon.

It is important to remember that mitral regurgitation is dynamic and is affected by loading conditions. Reduction of afterload or intravascular volume at the time of the operation may reduce the true severity of the regurgitation. When mitral regurgitation is less significant than expected, the intravascular blood volume should be expanded and systemic vascular resistance should transiently be increased, by using repeated boluses of IV phenylephrine. The velocity of mitral regurgitation, and therefore display of its jet by Colour Doppler, depends on the pressure difference between the left atrium and left ventricle, which is higher in the presence of hypertension. The size of the jet in the left atrium is also very sensitive to changes in colour gain (directly proportional) and pulse repetition frequency (PRF) (inversely proportional). In any case, remember that the true assessment of the degree of mitral regurgitation is done by transthoracic exam.

The Degenerative Mitral Valve Regurgitation:

From Geometrical Echocardiographic Concepts to Successful Surgical Repair 19

For this category of patients, in order to avoid SAM, the surgeon must be informed and aware of each element stated above (e.g. hypertrophic septum associated or not with large posterior leaflet and / or small mitral annulus etc) and the surgical approach should be tailored accordingly. If SAM should appear, its management consists of volume expansion, withdrawal of positive inotropic agents and sometimes use of short acting betablockers like esmolol. However, there is one type of SAM which is irreversible, having a 'surgical mechanism': in case of large P2 quadrangular resection without sliding plasty. This situation calls for a second run pump, to perform the sliding. This is particularly why the

Left ventricular outflow tract obstruction caused by SAM has been described as a complication of mitral repair. It has generally been attributed to the implantation of an annuloplasty ring or to various surgical techniques that alter the normal systolic narrowing of the antero-posterior diameter of the mitral annulus, or due to the displacing the mitral coaptation level towards the interventricular septum. The period immediately after cardiopulmonary bypass is the most crucial time for the development of SAM. This is due to reduced peripheral vascular resistance associated with hypovolemia and hypotension, which have a particular impact when the left ventricular cavity is small. This adverse effect is determined by a hyper dynamic state (increased kinetic energy of blood flow induced by

Mild degrees of LVOT dynamic obstruction after mitral valve repair often respond favourably to conservative treatment, as stated before: discontinuing inotropic agents in order to decrease contractility and heart rate, volume loading to increase preload, and augmenting afterload with pure α-agonists (such as phenylephrine) (Benea, 2005). If these measures prove inadequate, reoperation upon the mitral valve—including the performance of a sliding plasty or folding reconstruction that reduces the antero-posterior height of the posterior leaflet, the implantation of an annuloplasty ring of a larger size or the removal of the annuloplasty ring—may prove necessary. In refractory cases, even prosthetic mitral

Based on the Prolapsed Score and on the structured echocardiographic analyses of the mitral valve, the surgical strategy has to be personalised. In order to choose the right surgical approach and to be able to interact with the surgeon, the echocardiographer needs to know the surgical techniques suitable for the given case. Building a trust-based relationship between the surgeon and the echocardiographer is crucial for the surgical

This approach allows the surgeon to make two types of surgical planning, both necessary: one is the planning with 'the closed atrium', meaning the mental planning based on the echocardiographic findings. The other one is performed after the left atrium was opened and the valve is directly inspected. In our experience the two coincide in most of the cases, due to standardization of the echo exam, to the presence of the echocardiographer in the

Recently, the importance of performing the mitral valve repair using the most 'physiological' approach has become crucial. Single valve orifice but also posterior mitral

result. Each case has to be discussed by the surgical team prior to the operation.

operating room and due to the dialogue with the surgical team.

echocardiographer has to be aware of the surgical technique in the given case.

catecholamines)*,* associated with left ventricular hypovolemia.

valve replacement has been reported.

**2.7.3 Tailored surgical strategy** 

The use of three-dimensional echocardiography for the evaluation of the mitral valve disease is rapidly evolving, especially in conjunction with the transesophageal echocardiography. One of the explanations of this extensive use is that the mitral valve rends itself to detailed 3D imaging from the left atrial perspective, as viewed by the surgeon (Shah & Raney, 2011). In our experience, three-dimensional echocardiography allows a reliable 'volumetric' evaluation with an excellent perspective on the whole mitral valve complex. Moreover, it permits an accurate (even more than the 2D echo) localisation of the various lesions. Still, the resolution and quality of the 3D images do not match those of the 2D echo.

### **2.7.2 Prepump examination: Risk of systolic anterior motion**

Another important mission of the prepump examination is the identification of patients at risk for systolic anterior motion (SAM) of the anterior leaflet and subsequent functional mitral regurgitation. Fig 15 (A,B,C). The selection of patients at risk for SAM is already possible with the transthoracic approach. These patients usually have a small and /or hyper dynamic left ventricle, hypertrophy of the inter-ventricular septum, large posterior mitral leaflet, small mitral annulus and "narrow" LVOT (revealed by a reduced distance between the inter-ventricular septum and the coaptation line). One elegant study has indicated which could be the two echocardiographic indexes that may identify the patients at risk for SAM after surgery: the first is the ratio between the anterior and the posterior mitral leaflet (AL/PL) inferior to 1.3; the second is the distance from the coaptation line to the interventricular septum (C-Sept) equal or inferior to 2.5cm. (Maslow, 1999).

Fig. 15. (A,B,C). Postoperative transesophageal 2D exam showing the presence of SAM at the level of the anterior mitral leaflet (15 A, C, arrow) and the presence of severe mitral regurgitation (15 B).

The use of three-dimensional echocardiography for the evaluation of the mitral valve disease is rapidly evolving, especially in conjunction with the transesophageal echocardiography. One of the explanations of this extensive use is that the mitral valve rends itself to detailed 3D imaging from the left atrial perspective, as viewed by the surgeon (Shah & Raney, 2011). In our experience, three-dimensional echocardiography allows a reliable 'volumetric' evaluation with an excellent perspective on the whole mitral valve complex. Moreover, it permits an accurate (even more than the 2D echo) localisation of the various lesions. Still, the resolution and

Another important mission of the prepump examination is the identification of patients at risk for systolic anterior motion (SAM) of the anterior leaflet and subsequent functional mitral regurgitation. Fig 15 (A,B,C). The selection of patients at risk for SAM is already possible with the transthoracic approach. These patients usually have a small and /or hyper dynamic left ventricle, hypertrophy of the inter-ventricular septum, large posterior mitral leaflet, small mitral annulus and "narrow" LVOT (revealed by a reduced distance between the inter-ventricular septum and the coaptation line). One elegant study has indicated which could be the two echocardiographic indexes that may identify the patients at risk for SAM after surgery: the first is the ratio between the anterior and the posterior mitral leaflet (AL/PL) inferior to 1.3; the second is the distance from the coaptation line to the inter-

Fig. 15. (A,B,C). Postoperative transesophageal 2D exam showing the presence of SAM at the level of the anterior mitral leaflet (15 A, C, arrow) and the presence of severe mitral

regurgitation (15 B).

quality of the 3D images do not match those of the 2D echo.

**2.7.2 Prepump examination: Risk of systolic anterior motion** 

ventricular septum (C-Sept) equal or inferior to 2.5cm. (Maslow, 1999).

For this category of patients, in order to avoid SAM, the surgeon must be informed and aware of each element stated above (e.g. hypertrophic septum associated or not with large posterior leaflet and / or small mitral annulus etc) and the surgical approach should be tailored accordingly. If SAM should appear, its management consists of volume expansion, withdrawal of positive inotropic agents and sometimes use of short acting betablockers like esmolol. However, there is one type of SAM which is irreversible, having a 'surgical mechanism': in case of large P2 quadrangular resection without sliding plasty. This situation calls for a second run pump, to perform the sliding. This is particularly why the echocardiographer has to be aware of the surgical technique in the given case.

Left ventricular outflow tract obstruction caused by SAM has been described as a complication of mitral repair. It has generally been attributed to the implantation of an annuloplasty ring or to various surgical techniques that alter the normal systolic narrowing of the antero-posterior diameter of the mitral annulus, or due to the displacing the mitral coaptation level towards the interventricular septum. The period immediately after cardiopulmonary bypass is the most crucial time for the development of SAM. This is due to reduced peripheral vascular resistance associated with hypovolemia and hypotension, which have a particular impact when the left ventricular cavity is small. This adverse effect is determined by a hyper dynamic state (increased kinetic energy of blood flow induced by catecholamines)*,* associated with left ventricular hypovolemia.

Mild degrees of LVOT dynamic obstruction after mitral valve repair often respond favourably to conservative treatment, as stated before: discontinuing inotropic agents in order to decrease contractility and heart rate, volume loading to increase preload, and augmenting afterload with pure α-agonists (such as phenylephrine) (Benea, 2005). If these measures prove inadequate, reoperation upon the mitral valve—including the performance of a sliding plasty or folding reconstruction that reduces the antero-posterior height of the posterior leaflet, the implantation of an annuloplasty ring of a larger size or the removal of the annuloplasty ring—may prove necessary. In refractory cases, even prosthetic mitral valve replacement has been reported.
