Most common cause of mitral stenosis is rheumatic fever. Nearly 30 per cent of patients with rheumatic fever may go on to develop pure mitral valve disease while 50 per cent of mitral stenosis patients may not be able to recall any history of rheumatic fever. All other etiologies of mitral stenosis are very rare and include congenital mitral stenosis, mitral annular calcification,rheumatoid arthritis, and infective endocarditis.
Mitral Valve To understand mitral valve pathology better, it is important to have a clear idea of mitral valve structure. This may be understood from observations in surgical theater or from pathology specimens. The normal mitral valve is funnel shaped and has orifice area of about 4.0 sq.cm. It has following components:
1) Annulus: Annulus is a saddle shaped structure with medial and lateral portions forming the basal points and anterior and posterior aspects forming the apical points of the saddle.Anteriorly it merges with aortic annulus while posteriorly there is a C shaped discrete
fibrous annulus. The normal diameter is about 2.5 – 3.5 cm. and circumference is about 8 –9 cm. Normal motion and contraction contribute to the normal mitral valve function.
2) Posterior Left Atrial Wall: Change in the posterior left atrial wall distort mitral annulus and its contraction. Also sequential atrial and ventricular contraction that occurs in sinus rhythm is important for normal mitral valve closure as loss of sinus rhythm can cause mitral regurgitation.
3) Leaflets: Anterior leaflet is longer than wider and posterior leaflet is wider but shorter Anterior leaflet occupies about one third and posterior about two thirds of annulus. Total combined area of the leaflet is more than double that of annulus. The posterior leaflet has three scallops–medial, central and lateral. Redundancy, loss or restricted motion of leaflets results in mitral regurgitation.
4) Chordae: There are 12 primary chordae that subdivide in to secondary and tertiary chordae attaching leaflets to the papillary muscles. Anterior papillary muscle supplies chordae to lateral aspects while posteromedial papillary muscle supplies to medial aspects of the leaflets. Rupture, fusion or redundancy of chordae can lead to regurgitation.
5) Papillary Muscle: Two papillary muscles are situated at two thirds of the long axis from the base. Their systolic contraction helps leaflets to overcome the systolic pressure and remain closed during systole without prolapse. Impaired contraction of these due to any cause like ischemia, infarction, necrosis, fibrosis or altered geometry will lead to mitral regurgitation.
6) Left Ventricle: Global as well as regional contraction of ventricular muscle is important for normal mitral valve closure. Impaired contractility leads to mitral regurgitation by one or more mechanisms.
Pathology
Following rheumatic fever, over next few years to decades, the typical funnel shaped mitral valve assumes a fish mouth appearance. During rheumatic fever endocardium of the leaflets gets inflamed, edematous and develops pin head vegetations at the tips or along the line of closure.These heal with fibrosis resulting in thickening of the leaflets with limited mobility. Some times there may be calcific deposits over the leaflets. The commissures get fused and in diastole the larger anterior leaflet pulls the posterior leaflet anteriorly. This decreases the valve opening in diastole. Thickened and fused chordae further limit the opening of the valve. Subvalvular apparatus, i.e., the chordae may fuse to such an extent that a secondary orifice may develop below the mitral valve limiting the diastolic blood flow. The abnormal valvular flows due to initial valvulitis may further worsen the thickening and fibrosis of the leaflets progressively. The progression may be rapid in some patients due to repeated attacks of rheumatic carditis, genetic or hormonal factors or due to increased hemodynamic load as seen in manual laborers.
Pathophysiology
Normally there is no pressure gradient between left atrium and the left ventricle during diastole.However, as the valve orifice size decreases pressure gradient develops across mitral valve in diastole and the mean left atrial pressure increases. Increase in left atrial pressure would cause increase in the pulmonary artery wedge pressure. Increase in pulmonary artery wedge pressure would cause interstitial congestion by way of Starling’s forces and this presents as symptoms of dyspnoea. Further rise in pulmonary artery wedge pressure causes pulmonary edema and pulmonary arterial hypertension. In some patients there will be disproportionate rise in pulmonary artery pressure due to vasoreactivity of pulmonary arteries. As the pulmonary artery systolic pressure increases further the right ventricle fails and features of right heart failure would ensue.
Symptoms
The cardinal symptom of mitral stenosis is dyspnoea on exertion. Typically it progresses over a period of years. As the severity increases patient will have orthopnoea and paroxysmal nocturnal dyspnoea and class IV dyspnoea. The proximate reason for dyspnoea in mitral stenosis is increased pulmonary artery wedge pressure, which in turn depends upon the left atrial pressure.The pressure gradient across the mitral valve depends upon the size of the valve orifice, quantum of blood flow, i.e., cardiac output and the diastolic time period during which the blood flowoccurs. As the valve size decreases the gradient increases. Increase in cardiac output either due to exercise, pregnancy, anemia, fever or any other condition would increase the pressure gradient and there by the left atrial pressure. During sinus tachycardia or atrial fibrillation with fast ventricular rate, the diastolic time decreases and the pressure gradient and left atrial pressure increases. In all these situations in which the left atrial pressure increases patient will have increasing dyspnoea.
Patients with mitral stenosis sometimes report chest pain. This can be secondary to pulmonary artery hypertension and right ventricular ischaemia. Sometimes pulmonary infarction due to pulmonary embolism can cause pleuritic type of chest pain in these patients.Palpitations in a patient with mitral stenosis usually herald the onset of atrial fibrillation. They may be paroxysmal or occur continuously at rest with increase on exertion. Some times they may precipitate pulmonary edema and heart failure. However, over a period of time symptoms tend to become quiescent.
Giddiness and syncope are unusual. They suggest severe mitral stenosis with limited cardiac reserve or fixed cardiac output. They should also raise a suspicion of ball valve thrombus in left atrium or left atrial myxoma.Pedal edema is a late manifestation in the natural history of mitral stenosis. It suggests right heart failure due to severe pulmonary hypertension or associated organic tricuspid valve disease or combination of both.
Physical Signs
A typical malar flush is described in mitral stenosis. It is difficult to appreciate in Indians. Pulse is normal or low volume. Atrial fibrillation is a common arrhythmia in patients with mitral stenosis.Presence of ventricular ectopics should raise a suspicion of digitalis toxicity. In a patient with pulmonary hypertension ‘a’ wave may be prominent in jugular venous pulse. With increasing severity of tricuspid regurgitation ‘v’ wave becomes prominent. With onset of atrial fibrillation ‘a’ waves disappear. While left ventricular enlargement is absent, with severe pulmonary artery hypertension, right ventricle may form the apex. First heart sound is loud, but with a calcific and non pliable valve it may be muffled. Intensity of pulmonary closure sound depends upon the severity of pulmonary artery hypertension. A loud opening snap (OS) indicates a pliable valve.Length of diastolic rumble at apex depends upon the severity of mitral stenosis. It may be mid diastolic or presystolic with mild mitral stenosis. Distance between aortic closure sound and opening snap indicates severity of mitral stenosis. Shorter A2–OS distance and longer murmur indicate severe mitral stenosis. Typically in patients with sinus rhythm mid diastolic murmur has presystolic accentuation. However, its presence in atrial fibrillation depends upon the cycle length. With severe pulmonary hypertension murmur of tricuspid regurgitation is present. Signs
of right heart failure are often seen in patients with tight mitral stenosis and severe pulmonary hypertension.Fig. 3.3: Timing of opening snap Investigations
Electrocardiogram
Electrocardiographic changes are not specific for mitral stenosis and are never diagnostic for any valvular heart disease. They essentially reflect pathophysiological changes. Left atrial enlargement seen in more than 90 per cent of patients is reflected as increase in p-wave duration (>120 m sec.) in lead II or P mitrale. The p-wave axis is between + 45 to – 30 degrees. QRS axis correlates well with the severity of the mitral stenosis and degree of pulmonary hypertension. In pure or predominant mitral stenosis, QRS axis less than 60 degrees suggests a valve area more than 1.3 sq. cm., while a an axis more than that would indicate a valve area less than 1.3 sq. cm.,right axis deviation also correlates with the degree of pulmonary hypertension. Absence of right axis deviation in the presence of features of pulmonary hypertension should suggest other associated valvular lesions causing left ventricular hypertrophy. Evidence of right ventricular hypertrophy in the form of R/S ratio more than 1 in lead V1 and poor progression of R-wave height in precordial leads also correlate well with the degree of right ventricular systolic pressure. Atrial fibrillation is common rhythm in patients with mitral stenosis and indicates a large left atrium.
Echocardiography
Echocardiography is diagnostic in mitral stenosis. There is varying degrees of thickening and calcification of leaflets with subvalvular fusion. Commissural fusion results in typical fish mouth appearance of mitral orifice as seen in para sternal short axis view. The same is responsible for anterior motion of posterior leaflet in diastole. Excursion of leaflets and E-F slope on M mode are decreased. Anterior mitral leaflet has a typical hockey stick appearance. Left atrium is enlarged and it becomes a source of clots. Morphological features of mitral valve are of importance in assessing the suitability of mitral valve for balloon valvuloplasty. These features are given in the table. A valve score less than 8 predicts a favourable outcome with balloon valvuloplasty, while a score more than 8 does not preclude valvuloplasty.
Mitral Valve To understand mitral valve pathology better, it is important to have a clear idea of mitral valve structure. This may be understood from observations in surgical theater or from pathology specimens. The normal mitral valve is funnel shaped and has orifice area of about 4.0 sq.cm. It has following components:
1) Annulus: Annulus is a saddle shaped structure with medial and lateral portions forming the basal points and anterior and posterior aspects forming the apical points of the saddle.Anteriorly it merges with aortic annulus while posteriorly there is a C shaped discrete
fibrous annulus. The normal diameter is about 2.5 – 3.5 cm. and circumference is about 8 –9 cm. Normal motion and contraction contribute to the normal mitral valve function.
2) Posterior Left Atrial Wall: Change in the posterior left atrial wall distort mitral annulus and its contraction. Also sequential atrial and ventricular contraction that occurs in sinus rhythm is important for normal mitral valve closure as loss of sinus rhythm can cause mitral regurgitation.
3) Leaflets: Anterior leaflet is longer than wider and posterior leaflet is wider but shorter Anterior leaflet occupies about one third and posterior about two thirds of annulus. Total combined area of the leaflet is more than double that of annulus. The posterior leaflet has three scallops–medial, central and lateral. Redundancy, loss or restricted motion of leaflets results in mitral regurgitation.
4) Chordae: There are 12 primary chordae that subdivide in to secondary and tertiary chordae attaching leaflets to the papillary muscles. Anterior papillary muscle supplies chordae to lateral aspects while posteromedial papillary muscle supplies to medial aspects of the leaflets. Rupture, fusion or redundancy of chordae can lead to regurgitation.
5) Papillary Muscle: Two papillary muscles are situated at two thirds of the long axis from the base. Their systolic contraction helps leaflets to overcome the systolic pressure and remain closed during systole without prolapse. Impaired contraction of these due to any cause like ischemia, infarction, necrosis, fibrosis or altered geometry will lead to mitral regurgitation.
6) Left Ventricle: Global as well as regional contraction of ventricular muscle is important for normal mitral valve closure. Impaired contractility leads to mitral regurgitation by one or more mechanisms.
Pathology
Following rheumatic fever, over next few years to decades, the typical funnel shaped mitral valve assumes a fish mouth appearance. During rheumatic fever endocardium of the leaflets gets inflamed, edematous and develops pin head vegetations at the tips or along the line of closure.These heal with fibrosis resulting in thickening of the leaflets with limited mobility. Some times there may be calcific deposits over the leaflets. The commissures get fused and in diastole the larger anterior leaflet pulls the posterior leaflet anteriorly. This decreases the valve opening in diastole. Thickened and fused chordae further limit the opening of the valve. Subvalvular apparatus, i.e., the chordae may fuse to such an extent that a secondary orifice may develop below the mitral valve limiting the diastolic blood flow. The abnormal valvular flows due to initial valvulitis may further worsen the thickening and fibrosis of the leaflets progressively. The progression may be rapid in some patients due to repeated attacks of rheumatic carditis, genetic or hormonal factors or due to increased hemodynamic load as seen in manual laborers.
Pathophysiology
Normally there is no pressure gradient between left atrium and the left ventricle during diastole.However, as the valve orifice size decreases pressure gradient develops across mitral valve in diastole and the mean left atrial pressure increases. Increase in left atrial pressure would cause increase in the pulmonary artery wedge pressure. Increase in pulmonary artery wedge pressure would cause interstitial congestion by way of Starling’s forces and this presents as symptoms of dyspnoea. Further rise in pulmonary artery wedge pressure causes pulmonary edema and pulmonary arterial hypertension. In some patients there will be disproportionate rise in pulmonary artery pressure due to vasoreactivity of pulmonary arteries. As the pulmonary artery systolic pressure increases further the right ventricle fails and features of right heart failure would ensue.
Symptoms
The cardinal symptom of mitral stenosis is dyspnoea on exertion. Typically it progresses over a period of years. As the severity increases patient will have orthopnoea and paroxysmal nocturnal dyspnoea and class IV dyspnoea. The proximate reason for dyspnoea in mitral stenosis is increased pulmonary artery wedge pressure, which in turn depends upon the left atrial pressure.The pressure gradient across the mitral valve depends upon the size of the valve orifice, quantum of blood flow, i.e., cardiac output and the diastolic time period during which the blood flowoccurs. As the valve size decreases the gradient increases. Increase in cardiac output either due to exercise, pregnancy, anemia, fever or any other condition would increase the pressure gradient and there by the left atrial pressure. During sinus tachycardia or atrial fibrillation with fast ventricular rate, the diastolic time decreases and the pressure gradient and left atrial pressure increases. In all these situations in which the left atrial pressure increases patient will have increasing dyspnoea.
Patients with mitral stenosis sometimes report chest pain. This can be secondary to pulmonary artery hypertension and right ventricular ischaemia. Sometimes pulmonary infarction due to pulmonary embolism can cause pleuritic type of chest pain in these patients.Palpitations in a patient with mitral stenosis usually herald the onset of atrial fibrillation. They may be paroxysmal or occur continuously at rest with increase on exertion. Some times they may precipitate pulmonary edema and heart failure. However, over a period of time symptoms tend to become quiescent.
Giddiness and syncope are unusual. They suggest severe mitral stenosis with limited cardiac reserve or fixed cardiac output. They should also raise a suspicion of ball valve thrombus in left atrium or left atrial myxoma.Pedal edema is a late manifestation in the natural history of mitral stenosis. It suggests right heart failure due to severe pulmonary hypertension or associated organic tricuspid valve disease or combination of both.
Physical Signs
A typical malar flush is described in mitral stenosis. It is difficult to appreciate in Indians. Pulse is normal or low volume. Atrial fibrillation is a common arrhythmia in patients with mitral stenosis.Presence of ventricular ectopics should raise a suspicion of digitalis toxicity. In a patient with pulmonary hypertension ‘a’ wave may be prominent in jugular venous pulse. With increasing severity of tricuspid regurgitation ‘v’ wave becomes prominent. With onset of atrial fibrillation ‘a’ waves disappear. While left ventricular enlargement is absent, with severe pulmonary artery hypertension, right ventricle may form the apex. First heart sound is loud, but with a calcific and non pliable valve it may be muffled. Intensity of pulmonary closure sound depends upon the severity of pulmonary artery hypertension. A loud opening snap (OS) indicates a pliable valve.Length of diastolic rumble at apex depends upon the severity of mitral stenosis. It may be mid diastolic or presystolic with mild mitral stenosis. Distance between aortic closure sound and opening snap indicates severity of mitral stenosis. Shorter A2–OS distance and longer murmur indicate severe mitral stenosis. Typically in patients with sinus rhythm mid diastolic murmur has presystolic accentuation. However, its presence in atrial fibrillation depends upon the cycle length. With severe pulmonary hypertension murmur of tricuspid regurgitation is present. Signs
of right heart failure are often seen in patients with tight mitral stenosis and severe pulmonary hypertension.Fig. 3.3: Timing of opening snap Investigations
Electrocardiogram
Electrocardiographic changes are not specific for mitral stenosis and are never diagnostic for any valvular heart disease. They essentially reflect pathophysiological changes. Left atrial enlargement seen in more than 90 per cent of patients is reflected as increase in p-wave duration (>120 m sec.) in lead II or P mitrale. The p-wave axis is between + 45 to – 30 degrees. QRS axis correlates well with the severity of the mitral stenosis and degree of pulmonary hypertension. In pure or predominant mitral stenosis, QRS axis less than 60 degrees suggests a valve area more than 1.3 sq. cm., while a an axis more than that would indicate a valve area less than 1.3 sq. cm.,right axis deviation also correlates with the degree of pulmonary hypertension. Absence of right axis deviation in the presence of features of pulmonary hypertension should suggest other associated valvular lesions causing left ventricular hypertrophy. Evidence of right ventricular hypertrophy in the form of R/S ratio more than 1 in lead V1 and poor progression of R-wave height in precordial leads also correlate well with the degree of right ventricular systolic pressure. Atrial fibrillation is common rhythm in patients with mitral stenosis and indicates a large left atrium.
Echocardiography
Echocardiography is diagnostic in mitral stenosis. There is varying degrees of thickening and calcification of leaflets with subvalvular fusion. Commissural fusion results in typical fish mouth appearance of mitral orifice as seen in para sternal short axis view. The same is responsible for anterior motion of posterior leaflet in diastole. Excursion of leaflets and E-F slope on M mode are decreased. Anterior mitral leaflet has a typical hockey stick appearance. Left atrium is enlarged and it becomes a source of clots. Morphological features of mitral valve are of importance in assessing the suitability of mitral valve for balloon valvuloplasty. These features are given in the table. A valve score less than 8 predicts a favourable outcome with balloon valvuloplasty, while a score more than 8 does not preclude valvuloplasty.
Measurement of mitral valve and gradients across mitral valve are of importance in clinical decision making. Mitral valve area can be measured by planimetry from para sternal short axis view. Alternatively it can also be measured by different Doppler methods including continuity equation, pressure half time (PHT), and proximal isovelocity surface area methods. Mitral stenosis is considered mild if mitral valve area is >1.5 cm 2 , moderate if it is between 1.1 to 1.5cm 2 and severe if it is equal to or less than 1.0 cm 2 . In patients with atrial fibrillation valve area as well as trans valvular gradients are better measured as an average of 5–10 cycles. In the presence of aortic regurgitation, ASD and non compliant left ventricle mitral valve area calculation by PHT method is fallacious. Similarly continuity equation is not applicable in the presence of mitral regurgitation. Errors in measurement are decreased if the color flow mapping is used to direct the continuous wave Doppler beam. While calculated valve area is independent of cardiac output,gradients can be erroneously low with bradycardia and low cardiac output state even in the presence of tight mitral stenosis.Tran esophageal echocardiogram is helpful in detecting left atrial clots prior to planned balloon valvuloplasty or after an embolic event. Valve morphology can also be better assessed.
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| Echocardiographic Score Used to Predict Outcome of Balloon Valvulopasty |
Cardiac Catheterization
Cardiac catheterization is rarely needed to diagnose mitral stenosis. An end diastolic gradient more than 5 mm Hg. across mitral valve as measured by the gradient between pulmonary artery wedge pressure and left ventricular diastolic pressure diagnoses mitral stenosis. Pressure measurements are mandatory prior to balloon mitral valvuloplasty. Heart rate and cardiac output have to be considered while evaluating pressure gradients. Mean pressure gradient as measured by cardiac catheterization closely approximate to that measured by Doppler examination. Mitral valve area is calculated using Gorlin’s formula from the cardiac catheterization tracings.
Treatment
Presence of symptoms or any complications is an indication for treatment. Apart from penicillin prophylaxis no other treatment is warranted for an asymptomatic patient. Asymptomatic patients even with mild to moderate stenosis should avoid heavy unaccustomed exertion as it may precipitate pulmonary edema. Periodic evaluation including echocardiographic examination should be advised. Young women with mitral stenosis should plan pregnancy as even those with mild to moderate stenosis may become symptomatic during pregnancy.
Medical Treatment
Scope of medical treatment is limited and it is only palliative and not specific. Patients with mild to moderate mitral stenosis with minimal symptoms may be managed on medical treatment.Similarly patients who are not candidates for any intervention may be managed on medication.The principles are to relieve symptoms by diuretics, decrease heart rate and prevent thrombo embolic complications in patients with atrial fibrillation or in those with large left atrial chambers. In patients with sinus tachycardia without severe pulmonary artery hypertension beta blockers are the drug of choice. Beta blockers have to be given cautiously in those with severe pulmonary hypertension as sudden death may be precipitated. Beta blockers, calcium channel lockers or digoxine may be given to control ventricular rate in those with atrial fibrillation. In the absence of pulmonary hypertension and atrial fibrillation digoxine has limited role.Rheumatic fever and infective endocarditis prophylaxis needs to be advised.
Balloon Valvuloplasty
Whenever feasible valvuloplasty is the treatment modality of choice. One has to make sure that the valve is suitable and expertise to do the procedure is available. Surgical stand by is desirable.Immediate and long term results are directly related to pliability of the valve. With a pliable valve better valve area can be achieved and chance of immediate severe mitral regurgitation is less. A
thorough trans thoracic echocardiography is mandatory prior to performing the procedure.Similarly in those with atrial fibrillation and in those with left atrial diameter more than 4 cm.trans esophageal examination (TEE) should be done to rule out the presence of any left atrial thrombi. TEE is also helpful in assessing the degree of associated mitral regurgitation if any.Patient with left atrial appendage clot may be given oral anticoagulants and followed closely over next few months till the clot dissolves and then go for balloon valvuloplasty. Such a strategy may or may not be useful for left atrial clots as they may or may not dissolve with oral anti coagulants.
Higher valve scores and presence of commissural fibrosis and calcification may lead to sub optimal result and acute complications during the procedure. Mitral restenosis is a possibility after balloon valvuloplasty and the time taken for restenosis is dependent upon the initial pliability of the valve and the valve area achieved. Calcific valves tend to restenose early.Patients should continue with penicillin prophylaxis and have a periodic echocardiographic evaluation after balloon valvuloplasty. If symptoms recur repeat balloon valvuloplasty or valve replacement may be done. Complications of the procedure include local vascular complications,vasovagal episodes, cardiac perforation and tamponade, acute mitral regurgitation, embolic complication due to missed left atrial thrombi and very rarely infective endocarditis. In terms of simplicity and costs balloon valvuloplasty is superior to surgical commissurotomy and all patients should be first considered for balloon valvuloplasty.
Surgical Treatment
Available surgical treatment modalities include closed mitral valvotomy, open mitral valvotomy,and mitral valve replacement.With the advent of balloon valvuloplasty, closed mitral valvotomy is fast becoming extinct.Selection of patients is like that of balloon valvuloplasty. However, surgical morbidity is more. It may be considered in a rare situation, when balloon valvuloplasty cannot be done expeditiously in a very sick patient but surgical therapy is immediately available. Barring such a situation, there is hardly any scope for closed mitral valvotomy in modern day cardiology practice.Open mitral valvotomy is an attractive procedure for the surgeon but neither to the patient nor to the cardiologist. It has been proved in a randomized trial that open mitral valvotomy is not superior to balloon valvuloplasty both in immediate and long term results. It is much more costly procedure with higher risk of morbidity and mortality compared to balloon valvuloplasty. It may be considered in a rare patient who has tight mitral stenosis, sinus rhythm and a large left atrial clot with a pliable valve or along with other open cardiac surgical procedures like aortic valve replacement and coronary artery by pass surgery.
Mitral valve replacement is the procedure of choice in a symptomatic patient with tight mitral stenosis and a non pliable valve. Any valve replacement is like buying a new disease and patient should be economically and logistically prepared for it. Patient will be committed for life long anticoagulation and possibility of infective endocarditis. Mechanical prosthetic valves are prone for valve thrombosis, and embolic complications. Inadequately monitored anticoagulant treatment could lead to valve thrombosis or hemorrhagic complications. Presence of atrial fibrillation by itself is not an indication for vale replacement in a patient with pliable valve and tight mitral stenosis, as the long term complications are more with prosthetic valve. Surgery should not be denied to a patient with significant symptoms as the delay in surgery will expose the patient to the complications of mitral stenosis and will adversely affect the long term outcome of the surgery.These include severe pulmonary hypertension, which some times may not come down following
mitral valve replacement. A patient with advanced right heart failure and severe cardiac cachexia and hepatic and renal failure also is a poor candidate for surgery and patient should not be allowed to reach that stage before performing mitral valve replacement.
Whenever feasible valvuloplasty is the treatment modality of choice. One has to make sure that the valve is suitable and expertise to do the procedure is available. Surgical stand by is desirable.Immediate and long term results are directly related to pliability of the valve. With a pliable valve better valve area can be achieved and chance of immediate severe mitral regurgitation is less. A
thorough trans thoracic echocardiography is mandatory prior to performing the procedure.Similarly in those with atrial fibrillation and in those with left atrial diameter more than 4 cm.trans esophageal examination (TEE) should be done to rule out the presence of any left atrial thrombi. TEE is also helpful in assessing the degree of associated mitral regurgitation if any.Patient with left atrial appendage clot may be given oral anticoagulants and followed closely over next few months till the clot dissolves and then go for balloon valvuloplasty. Such a strategy may or may not be useful for left atrial clots as they may or may not dissolve with oral anti coagulants.
Higher valve scores and presence of commissural fibrosis and calcification may lead to sub optimal result and acute complications during the procedure. Mitral restenosis is a possibility after balloon valvuloplasty and the time taken for restenosis is dependent upon the initial pliability of the valve and the valve area achieved. Calcific valves tend to restenose early.Patients should continue with penicillin prophylaxis and have a periodic echocardiographic evaluation after balloon valvuloplasty. If symptoms recur repeat balloon valvuloplasty or valve replacement may be done. Complications of the procedure include local vascular complications,vasovagal episodes, cardiac perforation and tamponade, acute mitral regurgitation, embolic complication due to missed left atrial thrombi and very rarely infective endocarditis. In terms of simplicity and costs balloon valvuloplasty is superior to surgical commissurotomy and all patients should be first considered for balloon valvuloplasty.
Surgical Treatment
Available surgical treatment modalities include closed mitral valvotomy, open mitral valvotomy,and mitral valve replacement.With the advent of balloon valvuloplasty, closed mitral valvotomy is fast becoming extinct.Selection of patients is like that of balloon valvuloplasty. However, surgical morbidity is more. It may be considered in a rare situation, when balloon valvuloplasty cannot be done expeditiously in a very sick patient but surgical therapy is immediately available. Barring such a situation, there is hardly any scope for closed mitral valvotomy in modern day cardiology practice.Open mitral valvotomy is an attractive procedure for the surgeon but neither to the patient nor to the cardiologist. It has been proved in a randomized trial that open mitral valvotomy is not superior to balloon valvuloplasty both in immediate and long term results. It is much more costly procedure with higher risk of morbidity and mortality compared to balloon valvuloplasty. It may be considered in a rare patient who has tight mitral stenosis, sinus rhythm and a large left atrial clot with a pliable valve or along with other open cardiac surgical procedures like aortic valve replacement and coronary artery by pass surgery.
Mitral valve replacement is the procedure of choice in a symptomatic patient with tight mitral stenosis and a non pliable valve. Any valve replacement is like buying a new disease and patient should be economically and logistically prepared for it. Patient will be committed for life long anticoagulation and possibility of infective endocarditis. Mechanical prosthetic valves are prone for valve thrombosis, and embolic complications. Inadequately monitored anticoagulant treatment could lead to valve thrombosis or hemorrhagic complications. Presence of atrial fibrillation by itself is not an indication for vale replacement in a patient with pliable valve and tight mitral stenosis, as the long term complications are more with prosthetic valve. Surgery should not be denied to a patient with significant symptoms as the delay in surgery will expose the patient to the complications of mitral stenosis and will adversely affect the long term outcome of the surgery.These include severe pulmonary hypertension, which some times may not come down following
mitral valve replacement. A patient with advanced right heart failure and severe cardiac cachexia and hepatic and renal failure also is a poor candidate for surgery and patient should not be allowed to reach that stage before performing mitral valve replacement.
Complications of Mitral
Stenosis Hemoptysis
It is a common complication in patients with mitral stenosis and is related to the severity of mitral stenosis. Pulmonary edema and PND can cause hemoptysis as pulmonary capillaries may rupture due to sudden rise in pulmonary capillary pressure. Pulmonary embolism is common in patients with atrial fibrillation and heart failure and can lead to pulmonary embolism and hemoptysis.These patients with chronic pulmonary congestion are predisposed to bronchitis and winter bronchitis can be another cause of hemoptysis in these patients.
Atrial Fibrillation
As the left atrial size increase and atrial wall gets fibrosed, depolarization wave fronts get fragmented and atrial fibrillation sets in. Atrial fibrillation eventually develops in majority of patients with tight mitral stenosis. Initially it may be paroxysmal but later it becomes persistent and then chronic. Fast ventricular rate decreases diastolic filling time that would increase the
mean left atrial pressure. Loss of atrial contraction also contributes to increase in mean left atrial pressure. This would lead to worsening of clinical picture due to increased pulmonary wedge pressure and development of pulmonary edema. Very often patient who has been stabledeteriorates following the onset of AF and becomes symptomatic necessitating surgery or balloon valvuloplasty.
Left atrial dilatation and stasis due to fibrillation causes development of atrial and atrial appendage thrombus. Incidence of thrombo embolic complications in AF due to rheumatic mitral stenosis is 17 times more than that seen in lone atrial fibrillation. Not uncommonly systemic embolization is a presenting symptom in patients with atrial fibrillation. All patients with atrial fibrillation with or without presence of documented left atrial clot or systemic embolization should receive oral anticoagulants. Even when the atrial fibrillation is intermittent, oral anti coagulants should be given. Also in patients with dilated left atrium more than 5 cm oral anti coagulation is considered even when there is no documented atrial fibrillation. Onset of atrial fibrillation is not related to the severity of mitral stenosis since many other co morbid conditions can generate atrial fibrillation. Presence of atrial fibrillation but not the severity of mitral stenosis determines the indication for oral anticoagulants.
Attempts to regain sinus rhythm either by pharmacological means or by electric cardio version often fails if the underlying disease is not tackled. Any attempt to regain sinus rhythm should be made only after excluding left atrial appendage clots. When amiodarone is given to a patient with atrial fibrillation and undiagnosed left atrial clot, sinus rhythm may suddenly be regained and embolization may occur with disastrous consequences. Hence one should be careful in starting amiodarone in a patient with mitral stenosis and atrial fibrillation. It is better to control ventricular rate by other means before starting amiodarone even when the patient is very sick. Trans esophageal echocardiogram is mandatory before starting amiodarone to a patient with mitral stenosis and AF. As far as possible, in patients with mitral stenosis sinus rhythm should be maintained. The best way of achieving this is by relief of mitral stenosis itself. After relieving mitral stenosis, if the patient has atrial fibrillation attempts should be made to regain sinus rhythm. Usually such attempts made before relieving mitral stenosis are futile or will not be long lasting. At the time of surgical correction either by way of open mitral valvotomy or mitral valve replacement surgeon should do maze procedure to regain sinus rhythm. If sinus rhythm is not regained after surgery or balloon mitral valvotomy, patient may be stared on amiodarone after excluding clots in left atrial appendage or left atrium. If after two weeks of treatment with amiodarone sinus rhythm is not regained one should attempt synchronized DC version after excluding left atrial thrombus. DC version may be ineffective when given without pretreatment with amiodarone. DC version should be given cautiously in sick patients with tight mitral stenosis as sometimes it may worsen patient’s condition and precipitate pulmonary edema. It has been shown that long term out come with mitral valve replacement is better in those in whom sinus rhythm has been restored than when mere rate control was achieved.
Other Rare Complications
Infective endocarditis is a relatively rare complication of mitral stenosis and in the present era one may unexpectedly find it following balloon intervention. Cardiac cirrhosis, and cardiac cachexia due to long standing heart failure, hoarseness of voice due to long standing pulmonary hypertension are other described complications due to mitral stenosis that are seldom seen today.
Mitral Stenosis and Pregnancy
Since mitral stenosis is often seen in young women, it is not uncommon to see young women with pregnancy complicated by mitral stenosis. Unlike mitral regurgitation, it is poorly tolerated.During pregnancy cardiac output, blood volume and heart rate–all increase. This leads to increased flow during shortened diastolic period and pressure gradients increase across mitral valve for any mitral valve area. Hence patients with even moderate mitral stenosis become quite symptomatic during pregnancy. These young women require proper counselling before marriage and conception but unfortunately due to social conditions this is never effective. Mild to moderate mitral stenosis (MVA < 1.3sq, cm) may safely sail through pregnancy, but often more sicker patients will end up with problems. It is not uncommon to see a pregnant woman with tight mitralstenosis presenting with pulmonary edema late in pregnancy. If seen in first trimester and the patient has more than mild mitral stenosis it is advisable to terminate the pregnancy and correct valvular lesion. If mitral stenosis at that time is mild to moderate and transvalvular gradients across mitral valve are low, pregnancy may be continued but close medical supervision is needed.Whenever symptomatic, such patient may be started on beta blockers and small dose of diuretics.These drugs can cause fetal growth retardation and should be given in the smallest doses required. If the patient with tight mitral stenosis is seen later in the pregnancy and is symptomatic, she should be offered balloon valvuloplasty if the valve is suitable. Closed mitral valvotomy and mitral valve replacement carry high risk of fetal wastage and maternal morbidity. However,during balloon valvotomy fetus may be exposed to radiation and proper lead shield has to be used and procedure completed by an expert in shortest possible time avoiding unnecessary fluoroscopic time. Pregnant patients with prosthetic mitral valve or with atrial fibrillation who require oral anticoagulants are usually managed with heparin during 6-12 weeks of pregnancy and again later during the last two weeks. Fetal teratogenecity and maternal valve related complications are least with this approach.
Juvenile Mitral Stenosis
Peculiar to developing countries is the problem of juvenile mitral stenosis. Patients with rheumatic fever develop tight mitral stenosis in their adolescence. In developed countries disease tends to present much later. This may be due to initial severe rheumatic carditis or recurrent rheumatic fever. Principles of management are similar to that in adults. Balloon valvuloplasty may be done as indicated and expertise is needed to do the same in young children safely.
Natural History of Mitral Stenosis
Untreated, mitral stenosis is a serious disease with observed 10-year mortality of 70–80 per cent in symptomatic patients. By 20 years virtually nobody survives. About 60 per cent die of progressive heart failure and about 20 per cent die of thrombo embolic complications.Mean survival drops to less than three years in patients with severe pulmonary hypertension.Younger asymptomatic patients or those with minimal symptoms, sinus rhythm and mild mitral stenosis have a better prognosis. However, even in these patients symptoms deteriorate in more than 50 per cent of patients over next 10 years. Though no formal studies are available treatment has significantly altered this natural history.
It is a common complication in patients with mitral stenosis and is related to the severity of mitral stenosis. Pulmonary edema and PND can cause hemoptysis as pulmonary capillaries may rupture due to sudden rise in pulmonary capillary pressure. Pulmonary embolism is common in patients with atrial fibrillation and heart failure and can lead to pulmonary embolism and hemoptysis.These patients with chronic pulmonary congestion are predisposed to bronchitis and winter bronchitis can be another cause of hemoptysis in these patients.
Atrial Fibrillation
As the left atrial size increase and atrial wall gets fibrosed, depolarization wave fronts get fragmented and atrial fibrillation sets in. Atrial fibrillation eventually develops in majority of patients with tight mitral stenosis. Initially it may be paroxysmal but later it becomes persistent and then chronic. Fast ventricular rate decreases diastolic filling time that would increase the
mean left atrial pressure. Loss of atrial contraction also contributes to increase in mean left atrial pressure. This would lead to worsening of clinical picture due to increased pulmonary wedge pressure and development of pulmonary edema. Very often patient who has been stabledeteriorates following the onset of AF and becomes symptomatic necessitating surgery or balloon valvuloplasty.
Left atrial dilatation and stasis due to fibrillation causes development of atrial and atrial appendage thrombus. Incidence of thrombo embolic complications in AF due to rheumatic mitral stenosis is 17 times more than that seen in lone atrial fibrillation. Not uncommonly systemic embolization is a presenting symptom in patients with atrial fibrillation. All patients with atrial fibrillation with or without presence of documented left atrial clot or systemic embolization should receive oral anticoagulants. Even when the atrial fibrillation is intermittent, oral anti coagulants should be given. Also in patients with dilated left atrium more than 5 cm oral anti coagulation is considered even when there is no documented atrial fibrillation. Onset of atrial fibrillation is not related to the severity of mitral stenosis since many other co morbid conditions can generate atrial fibrillation. Presence of atrial fibrillation but not the severity of mitral stenosis determines the indication for oral anticoagulants.
Attempts to regain sinus rhythm either by pharmacological means or by electric cardio version often fails if the underlying disease is not tackled. Any attempt to regain sinus rhythm should be made only after excluding left atrial appendage clots. When amiodarone is given to a patient with atrial fibrillation and undiagnosed left atrial clot, sinus rhythm may suddenly be regained and embolization may occur with disastrous consequences. Hence one should be careful in starting amiodarone in a patient with mitral stenosis and atrial fibrillation. It is better to control ventricular rate by other means before starting amiodarone even when the patient is very sick. Trans esophageal echocardiogram is mandatory before starting amiodarone to a patient with mitral stenosis and AF. As far as possible, in patients with mitral stenosis sinus rhythm should be maintained. The best way of achieving this is by relief of mitral stenosis itself. After relieving mitral stenosis, if the patient has atrial fibrillation attempts should be made to regain sinus rhythm. Usually such attempts made before relieving mitral stenosis are futile or will not be long lasting. At the time of surgical correction either by way of open mitral valvotomy or mitral valve replacement surgeon should do maze procedure to regain sinus rhythm. If sinus rhythm is not regained after surgery or balloon mitral valvotomy, patient may be stared on amiodarone after excluding clots in left atrial appendage or left atrium. If after two weeks of treatment with amiodarone sinus rhythm is not regained one should attempt synchronized DC version after excluding left atrial thrombus. DC version may be ineffective when given without pretreatment with amiodarone. DC version should be given cautiously in sick patients with tight mitral stenosis as sometimes it may worsen patient’s condition and precipitate pulmonary edema. It has been shown that long term out come with mitral valve replacement is better in those in whom sinus rhythm has been restored than when mere rate control was achieved.
Other Rare Complications
Infective endocarditis is a relatively rare complication of mitral stenosis and in the present era one may unexpectedly find it following balloon intervention. Cardiac cirrhosis, and cardiac cachexia due to long standing heart failure, hoarseness of voice due to long standing pulmonary hypertension are other described complications due to mitral stenosis that are seldom seen today.
Mitral Stenosis and Pregnancy
Since mitral stenosis is often seen in young women, it is not uncommon to see young women with pregnancy complicated by mitral stenosis. Unlike mitral regurgitation, it is poorly tolerated.During pregnancy cardiac output, blood volume and heart rate–all increase. This leads to increased flow during shortened diastolic period and pressure gradients increase across mitral valve for any mitral valve area. Hence patients with even moderate mitral stenosis become quite symptomatic during pregnancy. These young women require proper counselling before marriage and conception but unfortunately due to social conditions this is never effective. Mild to moderate mitral stenosis (MVA < 1.3sq, cm) may safely sail through pregnancy, but often more sicker patients will end up with problems. It is not uncommon to see a pregnant woman with tight mitralstenosis presenting with pulmonary edema late in pregnancy. If seen in first trimester and the patient has more than mild mitral stenosis it is advisable to terminate the pregnancy and correct valvular lesion. If mitral stenosis at that time is mild to moderate and transvalvular gradients across mitral valve are low, pregnancy may be continued but close medical supervision is needed.Whenever symptomatic, such patient may be started on beta blockers and small dose of diuretics.These drugs can cause fetal growth retardation and should be given in the smallest doses required. If the patient with tight mitral stenosis is seen later in the pregnancy and is symptomatic, she should be offered balloon valvuloplasty if the valve is suitable. Closed mitral valvotomy and mitral valve replacement carry high risk of fetal wastage and maternal morbidity. However,during balloon valvotomy fetus may be exposed to radiation and proper lead shield has to be used and procedure completed by an expert in shortest possible time avoiding unnecessary fluoroscopic time. Pregnant patients with prosthetic mitral valve or with atrial fibrillation who require oral anticoagulants are usually managed with heparin during 6-12 weeks of pregnancy and again later during the last two weeks. Fetal teratogenecity and maternal valve related complications are least with this approach.
Juvenile Mitral Stenosis
Peculiar to developing countries is the problem of juvenile mitral stenosis. Patients with rheumatic fever develop tight mitral stenosis in their adolescence. In developed countries disease tends to present much later. This may be due to initial severe rheumatic carditis or recurrent rheumatic fever. Principles of management are similar to that in adults. Balloon valvuloplasty may be done as indicated and expertise is needed to do the same in young children safely.
Natural History of Mitral Stenosis
Untreated, mitral stenosis is a serious disease with observed 10-year mortality of 70–80 per cent in symptomatic patients. By 20 years virtually nobody survives. About 60 per cent die of progressive heart failure and about 20 per cent die of thrombo embolic complications.Mean survival drops to less than three years in patients with severe pulmonary hypertension.Younger asymptomatic patients or those with minimal symptoms, sinus rhythm and mild mitral stenosis have a better prognosis. However, even in these patients symptoms deteriorate in more than 50 per cent of patients over next 10 years. Though no formal studies are available treatment has significantly altered this natural history.
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