Mitral Stenosis surgical indications
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Surgery and Device Based Therapy
Indications for Mitral Valvuloplasty
Patient selection
- Mitral stenosis due to rheumatic disease is becoming less common in the US but is very prevalent worldwide
- Symptoms of shortness of breath and valve area or less than 1.5 cm2 are indications for commissurotomy
- Unlike with the surgical approach, elevated pulmonary pressures or depressued LV function are not contraindications
- Wilkins score that describes valve anatomy is the best predictor of procedural success: it assigns points for leaflet mobility, valvular and subvulvular thickening and calcification degree (score of < 8 makes the patient a favorable candidate); Thus good quality echocardiogram is essential before qualifying the patient for the procedure
- Contraindications include presence of left atrial appendage clot, moderate to severe mitral regurgitation or other indications for open heart surgery
Technique
- 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
Hemodynamic and Clinical Outcomes
- Results of the commissurotomy should be assessed with hemodynamics and echocardiography
- If second inflation is needed mitral regurgitation should be assessed
- In general increasing valve area to greater than 1 cm2/m2 is an acceptable result
- Usually the valve area doubles and the pulmonary pressures degrease immediately
- 5 year survival is in the 90% range
Factors favouring successful percutaneous mitral 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
- not more than trivial mitral regurgitation
- no left atrial thrombus
- no commissural calcification.
Wilkins score
A scoring system exists to grade the morphological changes in the mitral valve during assessment with echocardiography. This takes into account 4 characteristics: leaflet mobility, leaflet thickening, valve calcification and involvement of the subvalvular apparatus. The involvement is graded from 0-4. A total score of more than 8 is predictive of a low success post percutaneous mitral valvuloplasty.[1]
References
- ↑ Wilkins GT, Weyman AE, Abascal VM, Block PC, Palacios IF. Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation. Br Heart J. 1988;60:299–308. doi: 10.1136/hrt.60.4.299