Is it time to say goodbye to thoracotomy for treatment of rheumatic mitral stenosis?S Sharma, BY Nair
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 0001307224
Source of Support: None, Conflict of Interest: None
Keywords: Balloon Dilatation, Human, India, Mitral Valve Stenosis, therapy,Rheumatic Heart Disease, therapy,Thoracotomy,
Rheumatic mitral stenosis continues to be a major cardiac problem in India, much of Asia, Latin America, Africa and the Middle East. Surgical closed commissurotomy for relief of mitral stenosis was first attempted in 1923 and was reported successful beginning in the 1940s. Although controversy as to the comparative benefits of open and closed surgical commissurotomy continues, currently both procedures are commonly performed in our country. Replacement of the valve remains the logical treatment in patients with heavily calcified and fibrosed valves and in those where stenosis coexists with significant regurgitation.
Inoue from Japan created history in 1982 when he explored the use of a balloon catheter for the treatment of mitral stenosis. Lock and colleagues in 1985 travelled to India to assess the feasibility of a single balloon technique in children and adolescents at G B Pant Hospital and All India Institute of Medical Science, New Delhi. In April 1986, AI Zaibag and group reported the use and superiority of the double balloon technique. During the ensuing years, several techniques, (and technical modifications) evolved. By March 1992, considerable experience has been generated with the use of double balloon (with or without the use of sheaths) and Inoue's single balloon technique all over the world. From Several large series,,, it is obvious that balloon valvotomy (commissurotomy) is a safe and effective non-operative treatment for a wide range of patients with mitral stenosis. The Inoue balloon may emerge as the technique of choice because of ease of performance leading to reduction in procedure and fluoroscopy time. In India by October 1991, approximately 1500 balloon commissurotomy procedures have been performed in around 15 centres and 1000 of these procedures have been performed in 4 centres (G B Pant Hospital, Delhi: AIIMS, Delhi: Nizam's Institute, Hyderabad and BYL Nair Hospital, Mumbai).
Cross sectional echocardiography studies have confirmed that baloon valvotomy increases the area of the mitral valve by producing commissurai separation, a mechanism akin to surgical commissurotomy. Successful balloon valvotomy results in immediate reduction in left atrial pressure and increase in cardiac output and mitral valve area; pulmonary arterial pressure and calculated pulmonary vascular resistance fall to a lower steady state in 6 to 24 hours. Virtually identical findings were reported by the Mayo Clinic group in 1954 after successful surgical mitral commissurotomy. Mitral valve areas achieved after the double balloon or Inoue technique are similar to those previously reported after surgical valvotomy and mitral valve replacement, which makes this an acceptable technique from a hemodynamic point of view. Detailed analysis reveals that balloon valvotomy produces on average a doubling of valve area, a marked increase in functional class that has been documented on objective exercise testing, and improvement in mitral valve area and functional class that is maintained for up to 3 years.
The indications for balloon valvotomy have expanded from only pliable valves to thick valves, valves with restenosis following previous surgical commissurotomy, and multivalvar (mitral and tricuspid, mitral and aortic) stenosis. The major contrainclications are presence of fresh clots in the left atrium or its appendage and associated more than grade 2 mitral regurgitation.
The results of balloon therapy, like those of surgical closed commissurotomy, are greatly influenced by the characteristics of the valve and its supporting structures. In order to predict the results of the procedure, echocardiographic scoring systems have been developed to evaluate mitral valve leaflet mobility, leaflet thickness, subvalvular thickening and calcification. The best results of balloon valvotomy are in patients with pliable valves. Patients with semipliable or rigid valves have variable results and should be selected carefully.
Technically, mitral balloon valvotomy is a difficult procedure and demands considerable expertise in transseptal catheterisation as well as in balloon dilatation. The mortality and morbidity with this procedure are significantly related to the learning phase. It is ironic that in our country only a few interventional cardiologists perform this procedure. The procedure mortality in our laboratory has been 0.3% (1 in 350 cases) and is less than 1% in most experienced centres. Cardiac tamponade related to transseptal catherterisation remains a feared complication. Systemic embolisation, including stroke, and ventricular rupture can occur rarely. The incidence of residual atrial septal defect after balloon commissurotomy has been reported in the 10-20% range and resolves in most cases during follow up. Minor increase in mitral regurgitation is common (20 - 46%) after both balloon valvotomy and closed surgical commissurotomy; however, severe mitral regurgitation is a less frequent complication, .
The efficacy of closed mitral commissurotomy has been well proved and its excellent palliative effect has been adequately documented. With the advent of cardiopulmonary bypass, many cardiac centres have elected to perform the open operation, and this change in practice has led to an on going controversy regarding the relative merits of the two techniques. Although there have been prior reports 17 of better results with surgical open commissurotomy than with closed commissurotomy, a recent long term study showed no advantage for the open versus the closed procedure. Hickey et at demonstrated that 5-10 and 20 year survival rates after surgical commissurotomy were 95%, 87% and 53% respectively. Importantly, the technique (open versus closed) used for the commissurotomy was not a risk factor for diminished survival, requirement of a second mitral commissurotomy or subsequent mitral valve replacement, occurrence of thromboembolism or long-term poor functional status. This recent report carries an extremely important message for us in India that in skilled and experienced centers and in appropriate patients there is no advantage to open commissurotomy over closed commissurotomy. In fact, Stanley John a strong proponent of closed mitral commissurotomy from Christian Medical College, Vellore reported short and long term results in 3,748 patients. He found good long term outcome after closed operation: the 24 year survival rate was 84% and thromboembolism and restenosis rates ranged from 0.03% to 0.16% per year and 0.24% to 1.14% per year, respectively. These reports,  should deter many cardiac centres in Bombay and other parts of India from switching over to open commissurotomy. In fact, my personal observation is that many young cardiac surgeons have not acquired adequate skiffs in performing closed mitral commissurotomy, an operation, which is unlikely to become obsolete in our country.
Balloon valvotomy offers certain distinct advantages to surgical commissurotomy and these include avoidance of thoracotomy, general anesthesia and blood transfusion. The discomfort is minimised and hospital stay is markedly reduced. Turi et al conducted a prospective randomised trial at Nizam's Institute of Medical Science, Hyderabad and compared results of percutaneous balloon and surgical closed commissurotomy in 20 cases each. The authors concluded that both modalities resulted in comparative hemodynamic improvement that is sustained through months of follow up. In fact, the results are sustained at 4 years followup and the incidence of restenosis in both groups is the same (personal communication). Another prospective study by Patel et al concluded that balloon and surgical commissurotomy are comparable in safety, but a larger valve area and greater increase in exercise time are achieved with balloon valvotomy. Our own experience with the Inoue balloon in 80 cases suggests similar findings. Zaibaq and colleagues studied 41 cases at one year follow up after double balloon valvotomy and found no case of restenosis. Hung et at reported no restenosis as long as 42 months later in patients who had pliable noncalcified valves. Further long-term results with balloon therapy are yet to be seen; however, it seems reasonable to expect that these will be similar to those reported with closed surgical valvotomy.
Given a choice, what should one choose - balloon, closed or an open commissurotomy? In our country, mitral stenosis is endemic and facilities for open heart surgery are limited. Open mitral commissurotomy requires cardiopulmonary bypass, is expensive and carries a mortaility and morbidity clearly in excess of closed surgery or balloon procedure. In my opinion, open mitral commissurotomy in our country should be restricted to 2 categories. The first group includes patients who have clots in the left atrium and the second consists of patients with valves having immobile leaflets or considerable chordal thickening. Kirklin  points out that an open surgical technique is preferable in this group, not only because of the more favourable outcome but also because with an open technique, valve replacement can be performed at that time should the morphology of the mitral valve be more unfavourable than expected.
What should be the procedure of choice in an institution in India where both balloon and closed mitral valvotomy can be performed with low risk of untoward events related to the procedure itself? The answer is not a straightforward one but favors percutaneous balloon valvotomy. As mentioned above, balloon valvotomy has several advantages (avoids thoracotomy, general anesthesia, blood transfusion, reduces hospital stay, etc) and in addition produces better or at least as favourable hemodynamic results as closed commissurotomy. Balloon therapy is distinctly superior to closed commissurotomy in patients with high surgical risk (e.g. severe pulmonary hypertension, associated cor pulmonale, poor left ventricular ejection fraction, class IV symptoms) where the post procedure period is very smooth. The most important barrier to the popularity of balloon thereapy is the cost of the equipment. In a public hospital like ours, closed mitral commissurotomy can be performed in Rs. 2000. A cost analysis by Turi et at revealed that balloon commissurotomy may substantially exceed the cost of surgical commissurotomy in developing countries, whereas it may represent a significant saving in industrialised nations.
The cost of balloon valvotomy can be significantly reduced by the reuse of equipment. A transseptal needle can be used in approximately 200 patients. The balloons can be reused 3-5 times or untile they burst. Presently in our department, the cost of the procedure has been reduced to Rs. 10,000-12,000 by the judicious reuse of equipment.
In our society, balloon therapy has a special place in unmarried females where operative scar is considered a social handicap. Balloon valvotomy is also preferable in patients with restenosis with favourable anatomy, and in patients with high surgical risk due to severe pulmonary hypertension or associated diseases. Preliminary data show that balloon may be preferable to surgery even in pregnant patients with mitral stenosis.
Despite the extremely favourable results of balloon mitral valvotomy in our department, this procedure may only complement and not replace the currently available surgical options. Reduction in the cost of accessories and training of more cardiologists in transseptal catheterisation may help in further popularising this most exciting technique.