Mitral balloon valvuloplasty

Approaches

The retrograde technique without transseptal catheterization⁽⁵⁾ has been used with good results, but its use is now very limited.

The transvenous or antegrade approach is most widely used. Transseptal catheterization is the first step of the procedure and one of the most crucial⁽⁶⁾.

Transseptal puncture is usually performed using a Brockenbrough needle and a dilator which is most often that of the Mullins sheath.

The following steps should be taken:

• ◆ A 5F pigtail is positioned retrogradely from the femoral artery to the right coronary sinus for identification of the aorta and systemic pressure monitoring

• ◆ Percutaneous access is via a puncture of the right femoral vein as this offers a direct approach from the inferior vena cava to the interatrial septum at the fossa ovalis. In very rare cases, transseptal catheterization has been performed using a transjugular or transhepatic approach⁽⁷⁾

• ◆ A 0.032-inch J-tipped guide wire is advanced into the superior vena cava, up to the origin of the left innominate vein, in anteroposterior view

• ◆ The catheter is advanced over the guide wire into the superior vena cava and the guide wire is removed

• ◆ The Brockenbrough needle is connected to a pressure line, which is continuously flushed, and is inserted into the dilator just inside the distal end under fluoroscopic guidance. When the needle reaches the desired position inside the catheter the flush is stopped and pressure is continuously monitored

• ◆ Initially, the tip of the catheter is orientated towards the right shoulder of the patient in anteroposterior view. Then, under continuous fluoroscopic and pressure monitoring, both catheter and needle are withdrawn downwards and rotated counterclockwise until contact with the septum is felt. Whatever the method used, the proximal arrow and the tip of the needle have a posteromedial position, looking from bottom to top in anteroposterior view. The angle is chosen according to the size of the left atrium (LA) (4 o’clock in normal size and up to 6 in a large atrium). In anteroposterior view, the correct position of the tip of the needle is usually mid way between the pigtail and the right atrial border in the horizontal axis and slightly below the horizontal line at the level of the pigtail. It is recommended to use a complementary view to provide further information on the orientation of the needle in the anteroposterior axis before puncturing the septum. This could be a lateral view with a target zone at the mid-part of the line between the pigtail and the spina, or right anterior oblique 30° with a target zone vertically in the middle of the line between the pigtail and the spina and below a horizontal line at the level of the pigtail (Fig. 40.1). For BMV using the Inoue technique, the preferred site for the transseptal puncture is usually slightly lower than the fossa ovale if the LA is severely enlarged

• ◆ Before puncturing the interatrial septum, the following parameters should be checked: right atrial pressure tracing, correct position, and tactile contact with the septum. If these criteria are fulfilled, the needle can be advanced

• ◆ Entry into the LA is indicated by changes in the pressure tracing. The dilator should be advanced only when assurance is obtained that the needle has crossed the septum. When both the needle and the catheter have crossed the septum, the needle is withdrawn while applying a counterclockwise rotation to the proximal part in order to orientate the catheter towards the mitral valve. LA pressure is then recorded.

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Fig. 40.1

Transseptal puncture. A) Anterior posterior view. The catheter and needle are at the level of the fossa ovale, below and lateral to the pigtail catheter which is positioned on the aortic cusps. B) Right anterior oblique view 30°. The catheter and the needle are below and posterior to the pigtail catheter, around mid-distance between the spina and the pig-tail catheter.

The procedure is performed under fluoroscopic guidance with several views, ideally using biplane fluoroscopy. Additional right atrial angiography has been proposed to better locate the puncture site, but today this has been largely replaced by echographic monitoring using either transoesophageal⁽⁸⁾ or intracardiac⁽⁹⁾ approaches.

Both echocardiographic techniques provide excellent imaging of the interatrial septum, which is useful to guide the orientation of the needle in the fossa ovale, to show proper positioning and to monitor the crossing of the septum and its tenting. Echocardiography is a useful adjunct in the early part of the operator’s experience. The drawbacks are the need for anaesthesia, or at least analgesia, in most patients when transoesophageal echocardiography (TEE) is performed, and the cost of the devices as regards intracardiac echocardiography. The recent introduction of real time three-dimensional (3D) transoesophageal echocardiography further improves imaging of the septum. In experienced teams, echocardiographic guidance is restricted to cases where there are known difficulties, such as severe thoracic deformity, or when unexpected difficulties occur.

Finally, transthoracic echographic guidance is seldom used because it is difficult to perform at the same time as fluoroscopic imaging. However, it could be helpful in experienced hands.

Devices

With regards to the balloons themselves, the double balloon technique and its variant, the multi-track balloons, are very seldom used and exclusively in developing countries where the economic constraints lead to reuse of the balloons. The metallic commissurotome has been abandoned.

The Inoue technique was the first one described⁽²⁾ and wide experience has now been acquired by a number of groups worldwide. The data currently available suggests that the Inoue technique eases the procedure and has equivalent efficacy and lower risk than the other techniques. In fact, the Inoue technique has already become the most popular in the world, having been used in more than 10 000 patients. The stepwise technique under echocardiographic guidance certainly allows the best use of the mechanical properties of the Inoue balloon and therefore optimizes the results⁽¹⁰⁾.

The Inoue balloon, composed of nylon and rubber micromesh, is self-positioning and pressure-extensible. It is large (24–30mm in diameter) and has a low profile (4.5mm). The balloon has three distinct parts, each with a specific elasticity, enabling them to be inflated sequentially. This sequence allows fast, stable positioning across the valve. There are four sizes of the Inoue balloon (24, 26, 28, and 30mm); and each is pressure-dependent, so its diameter can be varied by up to 4mm as required by circumstances.

The main steps are as follows:

• ◆ Balloon size is chosen in accordance with the patient’s height (26mm in very small patients or infants, 28mm in patients less than 1.60m, and 30mm in patients taller than 1.6m)

• ◆ After transseptal catheterization, the Inoue guide wire, which is a stiff guide wire with a soft curved tip, is introduced into the left atrium through the transseptal catheter which is then withdrawn. This should be done in AP view and care should be taken to avoid pushing the guide wire into the left atrial appendage (Fig. 40.2)

• ◆ The femoral entry site and the atrial septum are dilated using the Inoue dilator (14F) over the guide wire. Several passages are performed until less resistance is felt at the level of the septum and the groin (Fig. 40.3)

• ◆ After withdrawal of the dilator, the Inoue balloon, which is slenderized using a stretching tube, is introduced into the left atrium. If resistance is felt at any level, excessive pressure should be avoided to avoid impairment of the tip of the Inoue balloon, and alternative techniques should be used. If resistance occurs at the level of the femoral entry site despite adequate dilatation it is advisable to use a 16F sheath (Cook) and to introduce the balloon through it. If resistance occurs at the level of the interatrial septum it could be dilated using an 8F peripheral angioplasty balloon

• ◆ When the Inoue balloon is positioned into the left atrium, the guide wire and the stretching tube are withdrawn, which shortens the balloon

• ◆ After careful flushing, the stylet is introduced into the balloon catheter to direct it through the mitral valve. When the stylet has reached the distal part of the balloon, the fluoroscopy arm, which was until then in AP, should be turned to RAO 30

• ◆ The balloon is inflated sequentially

• ◆ Firstly, the distal portion is inflated with 1 or 2mL of a diluted contrast medium and acts as a floating balloon catheter to cross the mitral valve. Crossing of the valve needs simultaneous manipulation of the stylet, which is gently pulled and turned counterclockwise, and of the balloon, which is gently pushed forward. Several attempts could be necessary using different orientations of the tip of the balloon. In cases where the atrium is very large, or if the transseptal puncture is too anterior, the ‘Loop technique’ may be necessary (Fig. 40.4). If the crossing of the mitral valve is not possible using this technique it may be necessary to redo the transseptal puncture in a slightly higher position and more posteriorly

• ◆ When the balloon has crossed the mitral valve and is floating into the ventricular cavity, the distal part is further inflated, and the balloon is pulled back to anchor at the level of the valve. The inflation is pursued, leading to inflation of the proximal and medium part of the balloon. When the balloon has a bone shape, the smaller diameter being at the level of the mitral orifice, full inflation is performed. Then the balloon is rapidly deflated and withdrawn into the LA (Fig. 40.5). The total inflation/deflation time is less than 5s. The stylet is withdrawn and the balloon is flushed.

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Fig. 40.2

BMV using the Inoue technique Step 1. The Inoue guide wire is introduced into the left atrium through the transseptal catheter (AP view).

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Fig. 40.3

BMV using the Inoue technique Step 2. The Inoue balloon dilator is used to dilate the interatrial septum over the guidewire (AP view).

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Fig. 40.4

BMV using the Inoue technique Step 3. Crossing of the mitral valve using the loop technique A large loop is created in the distal par of the balloon. The stylet tip is withdrawn to a point at 5cm from the tip of the balloon. The stylet is rotated clockwise. Only the balloon is advanced, which causes the catheter to form a loop in the left atrium and facilitate entry in the left ventricle. After the balloon has crossed the mitral orifice the balloon is withdrawn slowly to break the loop in the catheter in the left atrium and complete the inflation of the balloon.

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Fig. 40.5

BMV using the Inoue technique. The four sequences of inflation of the Inoue balloon catheter (RAO 30° view). A) Inflation of the distal portion of the balloon, which is thereafter pulled back and anchored at the mitral valve. B) Subsequent inflation of the proximal and middle portions of the balloon. At full inflation, the waist of the balloon in its midportion has disappeared. Reproduced from Topol EJ. Textbook of Interventional Cardiology, 5^th edn. Philadelphia, PA: W.B. Saunders, 2007 with permission of Elsevier.

Heparin, usually 3000–5000IU, is administered after the first balloon inflation, ideally when echocardiographic examination has eliminated the presence of pericardial effusion.

Although echocardiography may be difficult to perform in the catheterization laboratory for logistical reasons, it provides essential information on the course of the mitral opening, which is of utmost importance when using the stepwise Inoue technique, and also enables detection of early complications such as a pericardial haemorrhage or severe mitral regurgitation. The accuracy of measurements of the mean mitral gradient during BMV is low because it is dependent on the loading conditions and cardiac output. It can be helpful in patients in sinus rhythm and stable condition, while it is of little help in those in atrial fibrillation and low output. Therefore, the measurement of valve area using planimetry from two-dimensional (2D) echocardiography appears to be the method of choice when it is technically feasible. Colour Doppler assessment is the method of choice for sequential evaluation of the changes in the degree of regurgitation. Commissural opening can be assessed by 2D echocardiography, or even better using 3D imaging⁽¹¹⁾ in the short-axis view.

The first inflation is performed 4mm below the maximal balloon size, and the balloon size is increased in steps of 1mm each. If mitral regurgitation has not increased >1/4, and the valve area is less than 1cm²/m² of body surface area, the balloon is re-advanced across the valve⁽⁵⁾ and BMV is repeated with a balloon diameter increased by 1mm (Fig. 40.6).

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Fig. 40.6

Step-wise Inoue technique according to echocardiographic monitoring. Decision-making during the stepwise dilation technique based on echocardiographic findings after each balloon dilation. +, incomplete split; ++, complete split; *, stop in cases of severely diseased valve or age older than 65 years. Reproduced from Topol EJ. Textbook of Interventional Cardiology, 5^th edn. Philadelphia, PA: W.B. Saunders, 2007 with permission of Elsevier.

The following criteria have been proposed for the desired endpoint of the procedure: 1) mitral valve area of more than 1cm²/m² of body surface area; 2) complete opening of at least one commissure (Fig. 40.7); or 3) appearance or increment of regurgitation of more than 1/4. It is vital that the strategy be tailored to the individual circumstances, taking into account clinical factors together with anatomic factors and the cumulative data of peri-procedural monitoring. For example, balloon size, increments of size, and expected final valve area are smaller in patients where surgery would be at high risk such as the elderly or pregnant women; in the presence of initially tight MS, extensive valve and subvalvular disease, and nodular commissural calcification.

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Fig. 40.7

3D echocardiography before and after BMV—short axis view. A) Mitral stenosis with bicommissural fusion before BMV. B) Splitting of both commissures after BMV.

When the results are judged to be satisfactory, the Inoue guide wire and stretching tube are introduced again in AP view. At this time it is crucial to avoid pushing the guide wire into the appendage. Then the balloon is slenderized and pulled back down to the femoral entry site. It is recommended that only the coiled portion of the guide wire remains outside the distal end of the balloon during the pullback.

After the procedure, the most accurate evaluation of valve area is achieved by echocardiography⁽¹²⁾. To allow for the slight loss during the first 24h, this should be performed 1–2 days after BMV, when the valve area may be evaluated by planimetry or from the continuity equation method because the half-pressure time is reputed invalid just after BMV because of acute compliance changes. Finally, the degree of regurgitation may be assessed by colour Doppler flow. In current practice, the use of TEE after BMV is limited to patients with severe mitral regurgitation to evaluate the mechanisms or, in case of doubt, the degree of post procedural mitral regurgitation.

Even though the considerable simplification resulting from the use of the Inoue balloon may lead to a false sense of security when applying the technique, BMV clearly should be restricted to teams that have extensive experience with transseptal catheterization and are able to perform an adequate number of procedures⁽¹³⁾. The interventionists who perform BMV must also be able to perform emergency pericardiocentesis.

Haemodynamics

BMV usually provides more than a 100% increase in valve area with a final valve area around 1.7–2cm^2(13–16). This improvement in valve function results in an immediate decrease in left atrial pressure and a slight increase in cardiac index. A gradual decrease in pulmonary arterial pressure and pulmonary vascular resistance is observed.

BMV has a beneficial effect on exercise capacity. In addition, studies have shown that this technique improves left atrial and left atrial appendage pump function.

Failures

The failure rates range from 1–17%^{(2,3,15–17)}. Failure is often due to an inability to puncture the atrial septum or position the balloon correctly across the valve. Most failures occur early in the investigator’s experience. Failures can also be due to unfavourable anatomy, such as severe atrial or predominant subvalvular stenosis.

Complications

Large series^(13–18) enable assessment of the risks of the technique.

Haemopericardium may be related to transseptal catheterization or to left ventricular perforation by the guide wires or balloons. Its incidence varies from 0.5–12%. Haemopericardium usually has immediate clinical consequences resulting in tamponade and should always be suspected when hypotension occurs during BMV. Haemopericardium related to the transseptal puncture mostly occurs when the operator is less experienced. Unfavourable patient characteristics such as severe atrial enlargement or severe thoracic deformity also increase risk. With the Inoue technique the risk of left ventricular perforation by the balloon is virtually eliminated. If haemopericardium is suspected, echocardiography should be performed urgently before deterioration occurs. This stresses the importance of the immediate availability of echocardiography when performing BMV. Haemopericardium requires immediate pericardiocentesis, ideally performed under echocardiographic guidance after reversal of anticoagulation. If this is successful, BMV can be re-attempted and the patient should be closely monitored. In most cases haemopericardium due to transseptal catheterization can be managed by pericardiocentesis, especially when it results from only an incorrect puncture by the transseptal needle. To minimize the incidence of this, complication training is of course crucial. In addition, BMV should not be performed in patients with bleeding disorders, in particular those with too high anticoagulation. Transseptal catheterization should not be performed if the INR is >1.2. In patients receiving intravenous heparin it should be discontinued 4h before the procedure and can be restarted 2h after. Vitamin K should not be given before the procedure in patients who are at high risk for left atrial thrombosis, and BMV should be delayed until a satisfactory level of coagulability is reached. To further increase safety the absence of haemopericardium could be verified using echocardiography before administrating heparin.

Embolism may be due to a thrombus that was pre-existing, mostly in the left atrial appendage, or which developed during the procedure due to air leaking from the balloon. Very rarely, it may be due to calcium. Embolism is encountered in 0.5–5% of cases. Cerebral embolism usually results in a stroke. Coronary embolism leads to transient ST segment elevation in inferior leads, which is well tolerated when it is due to microbubbles of air that can occur when using the Inoue balloon and which will resolve spontaneously. The treatment of cerebral embolism should be in collaboration with a stroke centre. Cerebral imaging should be performed on an emergency basis to rule out haemorrhage, and intra-arterial fibrinolytic therapy should be administered early in the absence of contraindication. In the case of persistent ST segment elevation, coronary angiography should be performed. If a coronary occlusion is present, coronary angioplasty can be performed, while thrombo-aspiration could be an attractive alternative. Although the incidence of embolism is low, its potential consequences are severe, and all possible precautions should be taken to prevent it. In particular, transoesophageal echocardiography should be performed a few days prior to intervention to rule out the presence of intra atrial thrombosis. The occurrence of air embolism may be decreased by careful venting of the Inoue balloon before use and finally repeated inflations in saline water to flush the last bubbles of air.

Severe mitral regurgitation is rare but represents an ever-present risk. Surgical findings⁽¹⁸⁾ have shown that it is most often related to non-commissural leaflet tearing, which could be associated with chordal rupture. In these cases, one or both commissures are often too tightly fused to be split. Severe mitral regurgitation may also be due to excessive commissural splitting, or in very rare cases, rupture of a papillary muscle. The frequency of severe mitral regurgitation ranges from 2–19%. As mitral regurgitation is usually initially well tolerated, surgery can be performed on a scheduled basis. The precise timing of intervention should be based on functional tolerance and surgical risk. Subsequent surgical treatment is usually necessary because the prognosis of patients with severe mitral regurgitation is usually poor, with secondary objective deterioration and a lack of symptom alleviation. In most cases, valve replacement is required because of the severity of the underlying valve disease. Conservative surgery has been successfully performed in cases of less severe valve deformity. The majority of cases of severe mitral regurgitation occur in patients with unfavourable anatomy. However, the occurrence of severe mitral regurgitation remains largely unpredictable for a given patient and its development depends more on the distribution of morphologic changes than on their severity. The available data suggests, but does not prove, that the stepwise Inoue technique combined with echocardiographic monitoring is likely to decrease the incidence of severe regurgitation, even if it does not eliminate it.

Although urgent surgery (within 24h) is seldom needed for complications (<1%), it may be required for massive haemopericardium resulting from left ventricular perforation intractable to treatment by pericardiocentesis. According to circumstances, this could be drainage of the pericardial effusion alone or could also include valve surgery. Less frequently, severe mitral regurgitation, leading to haemodynamic collapse or refractory pulmonary oedema may necessitate emergency surgery with the support of an intra-aortic balloon pump en route to the operating room. The exact arrangement for surgical backup varies from institution to institution, according to the severity of the condition being treated and the experience of the cardiologic and surgical teams.

The main causes of death are massive haemopericardium or the poor condition of the patient. The latter is often a factor in end-stage patients, such as elderly patients where BMV is attempted as a palliative procedure or in emergency cases where it is performed in patients in pulmonary oedema or, very occasionally, in cardiogenic shock. The fatality rate ranges from 0–3%. The decrease in fatality is related to the experience of the team in BMV, the availability of rescue surgery, and also to the selection of the patients.

The clinical importance of interatrial shunting was largely overemphasized in the early days of BMV. These shunts are usually small and without consequence since most of them will disappear on follow-up after successful BMV due to a reduced interatrial pressure gradient. In rare circumstances, right-to-left shunts may occur in patients with severe pulmonary hypertension when BMV is not successful and this may lead to hypoxemia. The frequency of interatrial shunts varies from 10–90% depending on the technique used for detection. Surgery has been very seldom necessary because of inter atrial shunting. On the other hand, if surgery is needed for unsuccessful BMV or restenosis, the interatrial septum should be looked at and septal tears sutured at the time of surgery. To our knowledge, no cases of percutaneous closure of such defects have been reported, and such a procedure is unlikely to be successful because the interatrial shunts are not due to defects similar to patent foramen ovale or congenital atrial septal defects but to longitudinal tears. The use of the Inoue technique has significantly decreased the incidence of this complication in comparison with other techniques. To further decrease the magnitude of the problem it is necessary to fully slenderize the Inoue balloon before withdrawal and also to pull the guide wire, leaving only the soft part of it exteriorized when withdrawing the balloon across the interatrial septum in order to avoid an ‘effect’, which may occur if the stiff part of the guide wire is out of the tip of the balloon during the manoeuvre.

Atrial fibrillation rarely occurs during the procedure. When it does, it is usually transient and resolves within a few hours under medical treatment. In rare cases, it requires electric countershock a few days after.

The incidence of transient, complete heart block is rare (<1%) and exceptionally requires the implantation of a permanent pacemaker.

Vascular complications are the exception when using the antegrade or transvenous approach. In teams experienced in transseptal catheterization, left heart catheterization may be avoided to simplify the procedure and further reduce the incidence of vascular complication as well as shortening the duration of hospital stay.

Endocarditis is extremely rare and does not justify prophylaxis before the procedure. The risk is higher when balloons are reused, which occurs in many centres in developing countries. The same holds to be true for transmissible infections such as hepatitis or AIDS.

Predictors of immediate results

Evaluation of immediate results is mainly based on haemodynamic criteria. The definition of good immediate results varies from series to series. The definition usually employed is a final valve area larger than 1.5cm² without mitral regurgitation greater than 2/4.

It is now agreed that the prediction of results is multifactorial^(14,19–21). In addition to morphological factors, preoperative variables such as age, history of surgical commissurotomy, functional class, small mitral valve area, presence of mitral regurgitation before valvuloplasty, sinus rhythm, pulmonary artery pressure, presence of severe tricuspid regurgitation, and procedural factors such as balloon size are all independent predictors of the immediate results. The identification of these variables has enabled predictive models to be developed with a high sensitivity of prediction. Nevertheless, the specificity is low, indicating insufficient prediction of poor immediate results. This low specificity is particularly true in regard to the lack of accurate prediction of severe mitral regurgitation.

1. Assessment of the severity

Intervention should be performed only in patients with significant MS, i.e. valve area<1.5cm². In patients with only mild mitral stenosis (valve area >1.5cm²) the risks of BMV probably outweigh the benefits, and these patients can usually be well managed by medical treatment.

BMV can occasionally be performed in patients with a slightly larger valve area who have a large body surface area and an objective functional limitation.

2. Exclusion of contraindications

Contraindications to transseptal catheterization, and therefore to BMV, include suspected left atrial thrombosis, severe hemorrhagic disorder, and severe cardiothoracic deformity.

The current guidelines consider a thrombus localized in the LA as a contraindication⁽³¹⁾. This recommendation is self-evident if the thrombus is free-floating or is situated in the left atrial cavity. This also applies when it is located on the interatrial septum. When the thrombus is located in the left atrial appendage, and if the patient is clinically stable, anticoagulant therapy can be given for 2–6 months⁽³²⁾, and BMV can be attempted if a new transoesophageal examination shows that the thrombus has disappeared.

Other contraindications for BMV include more than mild mitral regurgitation, severe calcification, absence of commissural fusion, combined severe aortic valve disease, and severe tricuspid stenosis and regurgitation, or coronary disease requiring bypass surgery.

On the other hand, coexisting moderate aortic valve disease and functional tricuspid regurgitation are not considered as contraindications for the technique.

3. Assessment of the feasibility of BMV

Echocardiographic assessment allows the classification of patients into anatomic groups with a view to predicting the results. Most investigators use the Wilkins score⁽¹⁹⁾ (Table 40.1), whereas others⁽¹⁴⁾ use a more general assessment of valve anatomy (Table 40.2). Controversy exists regarding the most effective echocardiography scoring system in the prediction of results of mitral valvuloplasty. In fact, none of the scores available today have been shown to be superior to the others; and all echocardiographic classifications have the same limitations: 1) reproducibility is difficult, as the scores are only semi-quantitative; 2) lesions may be underestimated, especially with regards to the assessment of subvalvular disease; and 3) the use of scores describing the degree of overall valve deformity may not identify localized changes in specific portions of the valve apparatus (leaflets, commissures), which may increase the risk of severe mitral regurgitation. Therefore, we can only recommend the use of the system with which one is most familiar and at ease. More recently, scores that take into account the uneven distribution of the anatomic deformities of the leaflets or the commissural area have been developed. The preliminary results of these scores are promising but disputed, so further studies are needed to determine their exact value⁽³³⁾.

4. Evaluation of the functional status and extra cardiac condition

In symptomatic patients (Fig. 40.8)

BMV is the procedure of choice for patients at high risk or when surgery is contraindicated, or in patients with favourable characteristics. As regards high-risk patients, preliminary series have suggested that BMV can be performed safely and effectively in patients with severe pulmonary hypertension⁽³⁴⁾.

In Western countries, many patients with MS have concomitant non-cardiac disease, which may also increase the risk of surgery⁽¹⁾. In elderly patients, BMV results in moderate but significant improvement in valve function at an acceptable risk, although subsequent functional deterioration is frequent^(35,36). Therefore, BMV is a valid, if only palliative, treatment for these patients, in particular when the alternative of surgery carries a high risk because of age, comorbidities, and the evolutive stage of the disease.

BMV can be performed as a life-saving procedure in critically ill patients⁽³⁷⁾, as the sole treatment when there is an absolute contraindication to surgery, or as a ‘bridge’ to surgery in other cases. In this context dramatic

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Fig. 40.8

Management of severe symptomatic mitral stenosis (adapted from ESC Guidelines). BMV, balloon mitral valvuloplasty; CI, contraindication; MS, mitral stenosis. *Favourable characteristics for BMV can be defined by the absence of several of the following:

◆

Clinical characteristics: old age, history of commissurotomy, NYHA class IV, atrial fibrillation, severe pulmonary hypertension

◆

Anatomical characteristics: echo score>8, Cormier score 3 (calcification of mitral valve of any extent, as assessed by fluoroscopy), very small mitral valve area, severe tricuspid regurgitation.

improvement has been observed in young patients, but the outcome is very bad in elderly patients presenting with ‘end-stage’ disease who would probably be better treated conservatively.

BMV appears to be the procedure of choice in young adults with good anatomy—that is, pliable valves and only moderate subvalvular disease. Several studies have compared surgical commissurotomy with BMV, mostly in patients with favourable characteristics. They consistently showed that valvuloplasty is at least comparable to surgical commissurotomy as regards short- and mid-term follow-up up to 7 years⁽³⁸⁾. In addition, if restenosis occurs, patients treated by valvuloplasty could undergo repeat balloon catheterization or surgery without the difficulties and inherent risks resulting from pericardial adhesions and chest wall scarring⁽³⁹⁾.

In practice, in Europe BMV has virtually replaced surgical commissurotomy⁽¹⁾.

Much remains to be done to define the indications for patients with unfavourable anatomy, who are more common in Western countries. For this group, some advocate immediate surgery because of the less satisfying results of valvuloplasty, whereas others prefer BMV as an initial treatment for selected candidates, reserving the use of surgery for cases of failure or late deterioration^(40,41). Unfortunately, no randomized studies are available for these patients, and a comparison of the results of BMV with those of surgical series is difficult because of differences in the patients involved and the fact that the surgical alternative is usually valve replacement, since open commissurotomy is now very seldom performed, in particular in such cases. Valve replacement has its drawbacks: operative mortality, particularly in the elderly, and prosthesis-related complications whose cumulative incidence worsens the outcome, particularly in young patients who are most exposed to the risk of long-term deterioration. The indications in this subgroup of patients must take into account its heterogeneity with respect to anatomy and clinical status. In this group of patients, an individualistic approach allows for the multifactorial nature of prediction. Current opinion is that surgery can be considered the treatment of choice in patients with bicommissural or heavy calcification. On the other hand, BMV can be attempted as a first approach in patients with extensive lesions of the subvalvular apparatus or moderate or unicommissural calcification, even more so if the clinical status argues in favour of it. Surgery should be considered reasonably early if the results are unsatisfactory or if there is secondary deterioration.

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Fig. 40.9

Management of severe asymptomatic mitral stenosis (adapted from ESC Guidelines). BMV, balloon mitral valvuloplasty; CI, contraindication; MS, mitral stenosis. *Favourable characteristics for BMV can be defined by the absence of several of the following:

◆

Clinical characteristics: old age, history of commissurotomy, NYHA class IV, atrial fibrillation, severe pulmonary hypertension:

◆

Anatomical characteristics: echo score >8, Cormier score 3 (calcification of mitral valve of any extent, as assessed by fluoroscopy), very small mitral valve area, severe tricuspid regurgitation.

After surgical commissurotomy

This category of patients is of interest because recurrent MS is becoming more frequent than primary MS in Western countries, and because reoperation in this context is associated with a higher risk of morbidity and mortality, requiring valve replacement in most cases⁽⁴²⁾. BMV is feasible in this setting and significantly improves valve function. On the whole, the results are good, even if slightly less satisfactory than those obtained in patients without previous commissurotomy. This can probably be attributed to less favourable characteristics observed in patients previously subjected to operation. These encouraging preliminary data suggest that BMV may well postpone reoperation in selected patients with restenosis after commissurotomy. The indications for BMC in this subgroup of patients are similar to those for ‘primary BMV’, but echocardiographic examination must exclude any patients in whom restenosis is mainly due to valve rigidity without significant commissural refusion. The latter mechanism is often responsible for the exceptional cases of MS that develop in patients who have undergone mitral ring annuloplasty for the correction of mitral regurgitation.

During pregnancy

During pregnancy, surgery carries a substantial risk of fetal mortality and morbidity, especially if extra-corporeal circulation is required. The experience reported in the literature on BMV during pregnancy is limited to a few hundred patients, but suggests the following: from a technical point of view, during the last weeks of pregnancy (>20 weeks), which was when BMV was performed in most cases, the procedure may be more difficult because of the enlarged uterus. All measures should be taken to shorten the procedure. Contrast injection should be avoided to avoid the risk of hypothyroidy for the fetus. The aim should be to allow for a safe delivery, which is usually possible if valve area is over 1.5cm², and one should not excessively increase balloon size at the risk of creating severe mitral regurgitation with its inherent risks. The procedure is effective and results in normal delivery in most cases. As regards radiation exposure, BMV is safe for the fetus, provided that protection is given using a shield that completely surrounds the patient’s abdomen and that the procedure is performed after the 20^th week. Preliminary series have shown satisfactory development in the infants over 5–10 years follow-up⁽⁴³⁾. Nevertheless, one must bear in mind that, in addition to radiation, BMV carries the potential risk of complications that require urgent surgery. These data suggest that BMV can be a useful technique in the treatment of pregnant patients with MS and refractory heart failure despite medical treatment.