Percutaneous mitral balloon valvotomy (PMBV)


 * Associate Editor-In-Chief: Mohammed A. Sbeih, M.D. [mailto:msbeih@perfuse.org]

Overview
The development of this approach was done by Inoue in 1984 and Lock in 1985 for the treatment of mitral stenosis. For a long time, surgical commissurotomy and open valve replacement were the only methods by which mitral stenosis could be corrected. PMBV can be performed in chronically symptomatic patients, patients who present emergently with cardiac arrest or pulmonary edema and in asymptomatic patients who plan on childbearing or major noncardiac surgery. There is improvement in the mortality rates for mitral stenosis by intervention by percutaneous mitral balloon valvotomy or surgery.

The 2006 American College of Cardiology/American Heart Association (ACC/AHA) guidelines on the management of valvular heart disease recommended intervention in symptomatic patients with moderate to severe mitral stenosis.

Indications
In asymptomatic patients, intervention is recommended in moderate to severe MS and pulmonary hypertension (pulmonary artery systolic pressure >50 mmHg at rest or >60 mmHg with exercise).

When intervention is indicated in patients with rheumatic MS, the 2006 ACC/AHA guidelines recommend that Percutaneous mitral balloon valvotomy (PMBV) is preferred to surgery if the valve morphology is favorable and the patient does not have left atrial thrombus or moderate to severe (3+ to 4+) mitral regurgitation. Valve repair is performed if possible and preferred over valve replacement which has higher perioperative mortality and morbidity. Valve repair includes both open commissurotomy and placement of an annuloplasty ring after direct visualization of the valve.

The decision of whether valvuloplasty is superior to surgery depends on age (<60 favors valvuloplasty), and Cath/ECHO findings (e.g. LVEDP, degree of mobility, thickening and calcification). The average end result for the mitral valve surface area with both strategies is about 2 cm2. Moderate or greater MR (mitral regurgitation) and LA thrombus are contraindications to valvuloplasty.

Mitral stenosis is amenable to percutaneous mitral valvuloplasty if the echocardiography demonstrates :


 * Thickening confined to valve tips.
 * Good mobility of Anterior mitral valve leaflet.
 * Little chordal involvement.
 * No more than trivial mitral regurgitation.
 * No left atrial thrombus.
 * No commissural calcification.

To determine which patients would benefit from Percutaneous mitral balloon valvotomy (PMBV), a scoring system has been developed.2 Scoring is based on four echocardiographic criteria: Individuals with a score of &ge; 8 tended to have suboptimal results.3 Superb results with valvotomy are seen in individuals with a crisp opening snap, score < 8, and no calcium in the commissures.
 * Leaflet mobility.
 * Leaflet thickening.
 * Subvalvar thickening.
 * Calcification.

==ACC/AHA Guidelines- Indications for Percutaneous Mitral Balloon Valvotomy (DO NOT EDIT) == {{cquote|

Class I
1. Percutaneous mitral balloon valvotomy is effective for symptomatic patients (NYHA functional class II, III, or IV), with moderate or severe MS* and valve morphology favorable for percutaneous mitral balloon valvotomy in the absence of left atrial thrombus or moderate to severe MR. (Level of Evidence: A) 2. Percutaneous mitral balloon valvotomy is effective for asymptomatic patients with moderate or severe MS* and valve morphology that is favorable for percutaneous mitral balloon valvotomy who have pulmonary hypertension (pulmonary artery systolic pressure greater than 50 mm Hg at rest or greater than 60 mm Hg with exercise) in the absence of left atrial thrombus or moderate to severe MR. (Level of Evidence: C)

Class IIa
1. Percutaneous mitral balloon valvotomy is reasonable for patients with moderate or severe MS* who have a nonpliable calcified valve, are in NYHA functional class III–IV, and are either not candidates for surgery or are at high risk for surgery. (Level of Evidence: C)

Class IIb
1. Percutaneous mitral balloon valvotomy may be considered for asymptomatic patients with moderate or severe MS* and valve morphology favorable for percutaneous mitral balloon valvotomy who have new onset of atrial fibrillation in the absence of left atrial thrombus or moderate to severe MR. (Level of Evidence: C)

2. Percutaneous mitral balloon valvotomy may be considered for symptomatic patients (NYHA functional class II, III, or IV) with MV area greater than 1.5 cm2 if there is evidence of hemodynamically significant MS based on pulmonary artery systolic pressure greater than 60 mm Hg, pulmonary artery wedge pressure of 25 mm Hg or more, or mean MV gradient greater than 15 mm Hg during exercise. (Level of Evidence: C)

3. Percutaneous mitral balloon valvotomy may be considered as an alternative to surgery for patients with moderate or severe MS who have a nonpliable calcified valve and are in NYHA functional class III–IV. (Level of Evidence: C)

Class III
1. Percutaneous mitral balloon valvotomy is not indicated for patients with mild MS. (Level of Evidence: C)

2. Percutaneous mitral balloon valvotomy should not be performed in patients with moderate to severe MR or left atrial thrombus. (Level of Evidence: C)}}

Percutaneous Mitral Balloon Valvotomy (PMBV) Technique
The interventional cardiologist gains access to the mitral valve by making a puncture in the interatrial septum during cardiac catheterization. Inflation and rapid deflation of a single balloon or a double-balloon opens the stenotic valve. This mechanism is similar to that of surgical commissurotomy.


 * Transvenous transeptal technique is most commonly used with the Inoue balloon system.
 * Fossa ovalis lies usually at 1-7 o’clock but this orientation can be distorted in the presence of mitral stenosis where the interatrial septum becomes more flat, horizontal and lower.
 * For the femoral vein approach a 70 cm Brockenbrough needle should be used or an 8 Fr Mullins sheath and advanced under fluoroscopic guidance with pressure monitoring.
 * The latter is necessary to monitor for puncture into adjacent structures such as aorta.
 * Further catheter manipulation may be necessary to direct the catheter into the left ventricle through the mitral valve rather than towards one of the pulmonary veins.
 * The Mullins sheath is exchanged for a solid-core coiled 0.025 inch guidewire over which a 14 Fr dilator is placed.
 * This is exchanged for the Inoue balloon (24-30 mm) which inflates in three stages allowing for balloon self-positioning with the last inflation resulting in commissural splitting.

A transthoracic echocardiography should be done to measure the mitral valve area and assess the severity of regurgitation as a complication of the procedure. PMBV should be stopped if adequate valve area has been achieved or if the severity of mitral regurgitation has been increased.

Outcome

 * Complications are usually less than 5% of cases with low mortality.
 * Failure to puncture the interatrial septum is the most common reason for aborted procedure.
 * Most common complication is development of severe mitral regurgitation The indication for invasive treatment with either a mitral valve replacement or valvuloplasty is NYHA functional class III or IV symptoms.

Some trials showed that the outcome after PMBV is better than the surgical commissurotomy approach. Long term outcome studies showed that the mitral valve area was less in closed commissurotomy compared to other approaches, also the rate of restenosis was higher for closed commissurotomy approach.
 * PMBV versus open and closed surgical commissurotomy

Some trials showed that the outcome after mitral valve replacement combined with tricuspid valve repair (if the patient has tricuspid regurgitation) is better than PMBV in patients with severe mitral stenosis and severe tricuspid regurgitation.
 * PMBV versus mitral valve replacement combined with tricuspid valve repair