Balloon mitral valvotomy: our perspective.S Radhakrishnan, S Shrivastava
Keywords: Balloon Dilatation, Human, Mitral Valve,
Balloon valvotomy is a skilled procedure and should be done only at centres, which perform routine catheterization. The most important step in this procedure is the transseptal puncture, which as discussed by Dr. Sharma has a definite morbidity with a faily long learning curve. With introduction of the Inoue technique, the subsequent steps have been simplified and less and less complication prone.
Besides acquiring skill in the transseptal technique, there are still many unanswered questions regarding balloon valvotomy of the mitral valve:
1. What is the intermediate and long-term result of balloon valvotomy? Considering the fact that both balloon and surgical commissurotomy split the mitral valve by a similar mechanism, these are not expected to be different. Early follow-up shows that fall in gradients, valve area achieved and exercise tolerance is similar to that of surgical valvotomy. In our opinion, the most important determinant would be the adequacy of initial dilatation, which would itself be determined by valve morphology.
2. What is the ideal balloon size? Various criteria laid down depending on height of patient, body surface area, mitral annulus size give only a rough guideline. Before definite information is available graded dilatation (starting with smaller sized balloon) and repeated gradient measurements should be practiced as is done with the Inoue balloon.
3. Careful pre-dilatation evaluation of the mitral valve is very essential to achieve optimal results:
a) The global morphology of mitral valve apparatus is the most important determinant of adequacy of dilatation as shown by a number of studies.
b) It is not known whether focal areas of disease like calcification asymmetrical orifice because of irregularity of commissural fusion produce suboptimal results and more complications. The initial results are still controversial.
c) In our opinion calcified valves with severe subvalvular pathology should be subjected to balloon dilatation only as a "bail-out" procedure because earlier results with balloon and more wider experience with closed surgical valvotomy show suboptimal results and greater complication rates.
d) Presence of a left atrial thombus is a relative contraindication. However, successful mitral dilatation with Inoue balloon is possible in experienced hands even in the presence of a left atrial thrombus.
e) The exact incidence of peristent atrial shunt is being worked out by different workers and is still not known, though it seems to be a minor problem particularly with low profile Inoue balloon.
f) Last but not the least, the cost of the procedure may still prevent many of the patients in the lower socio-economic strata to opt f o r surgical commissurotomy. A major advantage would be the ability to reuse the balloon, which would definitely reduce the cost to the patient (presently we reuse each Inoue balloon 4- 5 times).
In our opinion surgical valvotomy should not be abandoned for the following reasons:
a) The disease being so common, surgical facilities should exist in smaller centres to deal with the problem. Balloon valvotomy should still be restricted to only major centres with trained personnel.
b) The cost of the procedure might still prohibit many patients of the lower socio-economic strata to opt for balloon valvotomy and no centre should be faced with the embarassing position of not being able to offer an alternative method.
c) Balloon mitral valvuloplasty in juvenile mitral stenosis can sometimes pose problems and one may have to resort to surgical valvotomy. Because of severe mitral stenosis (pin-point orifice) conventional "over-the-wire" technique has been known to cause severe hypotension while crossing the valve with Swan Ganz catheter. Recently (unpublished observation) with the Inoue technique we encountered an unusual problem wherein the slenderized balloon could not be accommodated in a relatively small left atrium and we had to resort to the "over-the-wire" technique.
d) There is a definite rate of "unsuccessful attempts" in balloon valvotomy,,, and to tackle these, surgical expertise has to be available. This is mainly restricted to the period during the learning curve and later occasionally with the "over- the-wire technique". With more experience and use of Inoue balloon, this rate may decrease markedly or become negligible. In the future, improved balloons with low cost may make balloon mitral valvotomy a still attractive alternative.