Mitral Valvuloplasty
Percutaneous Ballon Mitral Valvuloplasty (PTMV)
Mechanism
Percutaneous mitral valvuloplasty is more appropriately called percutaneous mitral commissurotomy because the balloon dilatation improves the valve orifice by separating the fused mitral commissures. As shown by echocardiographic, fluoroscopic, and anatomic studies, the expanding balloon splits fused commissures in the same manner as a surgical commissurotomy.
Indications
Symptomatic Mitral Stenosis
Pulmonary oedema
Pulmonary Hypertension
with Abnormal LV function.
Contraindications
Thrombus within the LA
Moderate or Severe Mitral Regirgitation
Aortic or Tricuspid valve lesions
Patient Selection
Patients should be selected for percutaneous transluminal mitral valvuloplasty based on both clinical and anatomic factors. In most cases they should be symptomatic, and mitral valve area as measured by echocardiography and hemodynamics should be 50mm Hg at rest or 60mm Hg with exercise in an otherwise asymptomatic patient represents disease severity that has reached the point where percutaneous commissurotomy should be considered . New atrial fibrillation is less clear an indication but should be considered, especially in patients with mitral valve morphology well suited for percutaneous commissurotomy.
Anatomic Factors in Patient Selection for Balloon Mitral Valvuloplasty
High-quality transthoracic and transesophageal echocardiography (TEE) is an essential part of proper patient selection. TEE prior to the planned valvuloplasty procedure excludes the presence of left atrial thrombus and moderate or greater mitral regurgitation. In addition to ensuring that there are no anatomic contraindications, echocardiography provides valuable information that helps the interventional cardiologist select patients and predict results . The ideal patient has pliable, noncalcified mitral leaflets and mild subvalvular disease. As the degree of subvalvular disease increases, the quality of the result with percutaneous mitral valvuloplasty decreases.
Mitral Valve Scoring (ECHOCARDIOGRAPHIC SCORING SYSTEM)
* Leaflet mobility
Highly mobile valve with restriction of only the leaflet tips Midportion and base of leaflets have reduced mobility Valve leaflets move forward in diastole mainly at the base No or minimal forward movement of the leaflets in diastole
* Valvular thickening
Leaflets near normal (4.5mm) Midleaflet thickening, marked thickening of the margins Thickening extends through the entire leaflets (5-8mm) Marked thickening of all leaflet tissue (>8-10mm)
* Subvalvular Thickening
Minimal thickening of chordal structures just below the valve Thickening of chordae extending up to one third of chordal length Thickening extending to the distal third of the chordae Extensive thickening and shortening of all chordae extending down to the papillary muscle
* Valvular Calcification
A single area of increased echo brightness Scattered areas of brightness confined to leaflet margins Brightness extending into the midportion of leaflets Extensive brightness through most of the leaflet tissue
Adding each of the components determines final score (maximum, 16 points). From Wilkins GT, Weyman AE, Abascal VM, et al
Patients with significant valve deformity and echocardiographic scores >8 should not be excluded a priori from consideration for percutaneous mitral valvuloplasty. There is no absolute contraindication to percutaneous mitral valvuloplasty in patients with higher echocardiographic scores, but patients with echocardiographic scores >8 require an individualized approach. The duration of palliation may be less than in patients with ideal valve morphology, and the acute procedure success rate is lower. When valve deformity is associated with other clear indications for open heart surgery, the decision is relatively simple. This includes patients with associated significant aortic stenosis or insufficiency, multivessel coronary artery disease, or those with severe tricuspid regurgitation in need of repair. When none of these indications are present or clear, percutaneous commissurotomy in patients with significant valve deformity can be a successful palliative therapy. This is an especially useful strategy in patients with borderline aortic insufficiency or stenosis, in whom a waiting period after mitral commissurotomy may allow for a more timely decision for double-valve replacement at a later date.
Inoue Balloon Technique
All antegrade approaches begin with the crucial first step of successful trans-septal catheterization. This technique not only requires successful access to the left atrium, but must also be through the proper part of the atrial septum to allow easy access to the mitral valve. After successful placement of a Mullins-type dilator and sheath into the left atrium and confirmation of its position by a hand injection of contrast, the patient is anticoagulated with heparin. Baseline hemodynamics are then recorded, confirming the appropriate degree of mitral stenosis. Subsequently, a special solid-core coiled 0.025-inch guidewire is introduced into the left atrium, and the Mullins sheath dilator system is removed. The femoral vein and interatrial septum are then dilated with a long 14F dilator over the coiled guidewire within the left atrium. The previously prepared, tested, and now slenderized Inoue balloon is then introduced over the guidewire into the left atrium. The Inoue balloon is made of nylon and rubber micromesh.
After the slenderized balloon has been positioned within the left atrium, the stretching tube is removed, and a preshaped "J"stylet is introduced into the Inoue balloon. The distal portion of the balloon is inflated slightly to aid in crossing the valve and to prevent intrachordal passage. By maneuvering the balloon catheter while rotating and withdrawing the stylet, the balloon tip will move anteriorly and inferiorly toward the mitral orifice. After the balloon catheter is across the mitral orifice, the distal portion of the balloon is inflated more fully and the catheter is pulled back gently to confirm that the inflated distal portion of the balloon is secure across the mitral valve. As further volume is added to the balloon, the proximal end inflates to lock the valve between the proximal and distal balloon. Inflation to precalibrated volume then dilates the valve orifice to the corresponding preset size. It is then allowed to deflate passively before it is withdrawn into the left atrium. The pressure gradient across the mitral valve is measured after each balloon dilatation, and echocardiography may be used to assess the mitral valve area, leaflet mobility,
If the first inflation has not resulted in a satisfactory increase in the mitral valve area, and the degree of mitral regurgitation has not increased, the balloon is then readvanced across the mitral valve and inflation repeated with the balloon diameter increased by 1 or 2mm by delivery of slightly more of the precalibrated syringe volume in a stepwise dilatation process that is repeated until the desired result is achieved.
Complications
In skilled hands, the failure rate of the procedure should be
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