Correspondence

Treatment of Mitral Stenosis

N Engl J Med 1995; 332:748-750March 16, 1995

Article

To the Editor:

In their editorial (Oct. 13 issue),1 Carabello and Crawford remind us that the therapy for mitral stenosis has come full circle. Just as fascinating is the way in which medical attitudes toward mitral stenosis have changed. Elliott Cutler made the first brave attempt at surgical treatment for mitral stenosis in Boston in 1923, when he inserted a knife through the apex of the left ventricle and blindly cut the valve at right angles to its natural orifice.2 Soon afterward, in 1925, Henry Souttar relieved mitral stenosis with his finger inserted through the atrial appendage — the first true commissurotomy.3 I have studied the writings of those times and was interested to see how, for over 20 years, medical opinion not only resisted the feasibility of relieving mitral stenosis but also argued that such relief was futile and irrelevant to the condition. In the most popular cardiology textbook of his day, Thomas Lewis wrote, “Although many symptoms may be complained of by patients suffering from mitral stenosis, there are none that can be ascribed properly and usefully to this deformity of the valve.” He went on to dismiss valvotomy because it was based on “an erroneous idea, namely, that the valve is the chief source of the trouble.”4

In 1948 three surgeons working independently performed successful valvotomies. The first was Charles Bailey, in June 1948, followed within days by Dwight Harken, who wrote to me, “I rushed to Joe Garland, Editor of the New England Journal of Medicine, and told him to get it published as soon as possible.” The third surgeon was Russell Brock, who selected eight suitable patients, the first in September 1948, and soon reported six successful outcomes.5

Closed mitral valvotomy was a brilliantly successful procedure and still is in cases of pure stenosis with a mobile valve, which are now best managed by balloon valvotomy. One wonders why Reyes and colleagues (Oct. 13 issue)6 chose to compare balloon valvotomy with an open operation, particularly in India, where the less expensive and highly effective operation of closed mitral valvotomy is still widely practiced.

Tom Treasure, M.D.
St. George's Hospital, London SW17 OQT, United Kingdom

6 References

1
Carabello BA, Crawford FA. Therapy for mitral stenosis comes full circle. N Engl J Med 1994;331:1014-1015
Full Text | Web of Science | Medline

2
Cutler EC, Levine SA. Cardiotomy and valvulotomy for mitral stenosis: experimental observations and clinical notes concerning an operated case with recovery. Boston Med Surg J 1923;188:1023-1027
Full Text | Web of Science

3
Souttar HS. The surgical treatment of mitral stenosis. BMJ 1925;2:603-606
CrossRef | Medline

4
Lewis T. Diseases of the heart: described for practitioners and students. 3rd ed. London: MacMillan, 1942.

5
Baker C, Brock RC, Campbell M. Valvulotomy for mitral stenosis: report of six successful cases. BMJ 1950;1:1283-1293
CrossRef | Web of Science | Medline

6
Reyes VP, Raju BS, Wynne J, et al. Percutaneous balloon valvuloplasty compared with open surgical commissurotomy for mitral stenosis. N Engl J Med 1994;331:961-967
Full Text | Web of Science | Medline

To the Editor:

Great caution should be exercised before concluding that most patients with mitral-valve stenosis should be treated with balloon valvuloplasty.

Open mitral valvotomy is a firmly established procedure in the treatment of mitral stenosis. It permits visualization of the mitral valve and precise incision of the fused commissures, chordae tendineae, and papillary muscles. The procedure is associated with a remarkably low rate of restenosis requiring valve replacement — less than 10 percent at 10 years in most studies.1 Subvalvular disease necessitating correction has been noted in over half of symptomatic patients needing relief of stenosis. The incidence of restenosis, which is closely associated with this factor, is minimal when the fused subvalvular apparatus is adequately repaired. In contrast, 4 of 30 patients undergoing open mitral valvotomy in the present study had restenosis at three years. Most proponents of open mitral valvotomy have advocated an early operation, not only to eliminate the mitral-valve gradient without producing insufficiency but also to prevent progressive fibrosis from the turbulent flow of blood.2 Even in highly selected patients with pure, severe, noncalcific stenosis, open commissurotomy results in greater improvement of hemodynamic values than does closed commissurotomy, both during exercise and at rest.

Reyes et al. admit that balloon valvuloplasty is a palliative procedure and that a substantial number of patients will eventually need a thoracotomy. Balloon valvuloplasty has been compared with closed mitral valvotomy; 60 to 70 percent of patients undergoing the latter procedure need reoperation at 10 years.3 The availability of a precise operation (open mitral valvotomy) has led most surgical centers to abandon the closed technique. Tricuspid regurgitation is a complication in up to 32 percent of patients presenting with mitral stenosis. Like closed mitral valvotomy, balloon valvuloplasty has the potential disadvantage of leaving the associated tricuspid-valve disease untreated. Regardless of the outcome of percutaneous mitral valvotomy, in the majority of patients, substantial tricuspid regurgitation does not decrease or resolve after the procedure.4 It will therefore be hard to convince the medical community to adopt balloon valvuloplasty — the medical equivalent of closed mitral valvotomy, a surgical procedure that has been proved inferior to open mitral valvotomy — except in highly selected patients.

Mukul Chandra, M.D.
Emory University, Atlanta, GA 30303

4 References

1
Mullin MJ, Engelman RM, Isom OW, Boyd AD, Glassman E, Spencer FC. Experience with open mitral commissurotomy in 100 consecutive patients. Surgery 1974;76:974-982
Web of Science | Medline

2
Spencer FC. A plea for early, open commissurotomy. Am Heart J 1978;95:668-670
CrossRef | Web of Science | Medline

3
Glenn WW, Goodyear AV, Stansel HC Jr, Calabrese C, Hume M. Mitral valvulotomy. II. Operative results after closed valvulotomy: a report of 500 cases. Am J Surg 1969;117:493-501
CrossRef | Web of Science | Medline

4
Sagie A, Schwammenthal E, Palacios IF, et al. Significant tricuspid regurgitation does not resolve after percutaneous balloon mitral valvotomy. J Thorac Cardiovasc Surg 1994;108:727-735
Web of Science | Medline

To the Editor:

The technique of balloon mitral commissurotomy involves atrial septostomy with the creation of a left-to-right atrial shunt in 19 to 87 percent of patients immediately after the procedure.1,2 Creation of an atrial septal defect secondary to percutaneous balloon mitral valvuloplasty will improve the clinical and hemodynamic characteristics of mitral stenosis.3 In patients with mitral stenosis, the only orifice for left atrial emptying is the stenosed mitral valve. The creation of an atrial septal defect provides an alternative exit for left atrial emptying, resulting in a diminution of the left atrial pressure, pulmonary-capillary wedge pressure, and mitral-valve gradient,3 and therefore in a larger calculated mitral-valve area, according to Gorlin and Gorlin's formula.4

The favorable hemodynamic benefits in the form of a lower mitral-valve gradient with a subsequently larger mitral-valve area in the valvuloplasty group may in part be artifactually related to the creation of an acquired atrial septal defect and not a true advantage over open surgical commissurotomy. Reyes et al. report that at the end of three years of follow-up, four patients had a left-to-right shunt with a pulmonary-to-systemic flow ratio of more than 1.5. Information on lower degrees of shunting is not provided. In addition, patients with a base-line mitral-valve area of 2.2 cm² were enrolled in the study, which creates some confusion about the definition of severe mitral stenosis.

Olayinka F. Sogade, M.D.
Imad A. Alhaddad, M.D.
Arnold R. Conrad, M.D.
Nassau County Medical Center, East Meadow, NY 11554

4 References

1
Casale P, Block PC, O'Shea JP, Palacios IF. Atrial septal defect after percutaneous mitral balloon valvuloplasty: immediate results and follow-up. J Am Coll Cardiol 1990;15:1300-1304
CrossRef | Web of Science | Medline

2
Yoshida K, Yoshikawa J, Akasaka T, et al. Assessment of left-to-right atrial shunting after percutaneous mitral valvuloplasty by transesophageal color Doppler flow-mapping. Circulation 1989;80:1521-1526
CrossRef | Web of Science | Medline

3
Perloff JK. The clinical recognition of congenital heart disease. 4th ed. Philadelphia: W.B. Saunders, 1994.

4
Gorlin R, Gorlin SG. Hydraulic formula for calculation of the area of stenotic valve, other cardiac valves and central circulatory shunts. Am Heart J 1951;41:1-1
CrossRef | Web of Science | Medline

To the Editor:

Reyes et al. conclude that balloon mitral valvuloplasty and open surgical commissurotomy have similar clinical and hemodynamic results. Their conclusions about the hemodynamic results are based on the absolute mitral-valve area and transmitral gradients. Mitral-valve area is a function of body-surface area, which in turn is determined by age, sex, genetic makeup, and nutritional status. Thus, measurements of mitral-valve area that were not normalized for body-surface area could have introduced a substantial error in the comparison of data between the two groups, which could have varied in body stature and, hence, in surface area. Similarly, the transmitral gradient is a function of the heart rate, besides being determined by the mitral-valve area. Since at higher heart rates, diastole tends to be disproportionately abbreviated, as compared with systole, measurements of the transmitral gradient that have not been corrected for the heart rate are also likely to vitiate the data.

Bharat Dalvi, M.D.
Great Ormond Street Hospital for Children, London WC1N 3JH, United Kingdom

To the Editor:

Reyes et al. used the double-balloon technique, which has largely been replaced in recent years by the Inoue single-balloon technique.1 The recently reported multicenter study of 4832 patients in China who successfully underwent percutaneous balloon mitral valvuloplasty with the Inoue single-balloon technique2 adds weight to the statement by Carabello and Crawford that “balloon valvotomy will probably replace closed surgical commissurotomy.”3

Tsung O. Cheng, M.D.
George Washington University, Washington, DC 20037

3 References

1
Cheng TO. Percutaneous balloon mitral valvuloplasty: are Chinese and Western experiences comparable? Cathet Cardiovasc Diagn 1994;31:23-28
CrossRef | Medline

2
Chen C, Cheng TO. Percutaneous balloon mitral valvuloplasty using Inoue technic: a multicenter study of 4,832 patients in China. Circulation 1994;90:I-65 abstract.

3
Carabello BA, Crawford FA. Therapy for mitral stenosis comes full circle. N Engl J Med 1994;331:1014-1015
Full Text | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: We thank Dr. Treasure for his remarks and refer him to our previous randomized trial comparing balloon valvuloplasty with closed commissurotomy,1 which was also performed in India.

Unlike Dr. Chandra, we believe the medical community has already adopted balloon valvuloplasty for patients with favorable anatomy. We suspect that the restenosis rates for open commissurotomy (which is also “palliative”) have been largely underreported in prior publications because of a reliance on largely subjective data; our data are based on serial prospective hemodynamic measurements, with 100 percent follow-up. None of our patients had severe tricuspid regurgitation. Among the 24 patients with mild regurgitation and the 10 patients with moderate regurgitation, there was a similar rate of resolution of pulmonary hypertension, which improved through three years of follow-up, a substantially longer period than the follow-up in the study to which Dr. Chandra refers.

We concur with the statement by Sogade et al. regarding the potential influence of left-to-right shunting on calculated valve areas. However, we do not believe this was a factor in our study. With the nine patients who had no evidence of shunting by oxymetry but had some flow across the septum by color Doppler echocardiography excluded, as well as the four patients with substantial shunting, the mitral-valve area at three years in the remaining balloon-valvuloplasty group was still 2.3±0.6 cm² (P = 0.002 for the comparison with the surgery group). With regard to the patient with severe mitral stenosis who had a calculated valve area of 2.2 cm² at base line, this patient's gradient was 15 mm Hg; the large calculated valve area reflected a high cardiac output.2 As shown in Figure 2 of our article, this was the only patient in whom the calculated valve area was larger than 1.5 cm² at enrollment.

We can reassure Dr. Dalvi that indexing the mitral-valve area for body-surface area has no effect on our findings. The base-line mitral-valve index in both groups was 0.7±0.2 cm² per square meter of body-surface area; at three years the index was 2.0±0.8 cm² per square meter in the balloon-valvuloplasty group and 1.3±0.5 cm² per square meter in the surgery group (P<0.001). We agree about the influence of the heart rate on diastole; however, the transmitral gradient, heart rate, and diastolic filling period were all measured and incorporated in our valve-area calculations.

We agree with Dr. Cheng's statement about the Inoue single-balloon technique and have also adopted it, although comparisons with the double-balloon approach have not demonstrated significant differences in outcomes.

Zoltan G. Turi, M.D
Wayne State University School of Medicine, Detroit, MI 48201

B. Soma Raju, M.D.
MediCiti Hospital, Hyderabad 500 004, India

2 References

1
Turi ZG, Reyes VP, Raju BS, et al. Percutaneous balloon versus surgical closed commissurotomy for mitral stenosis: a prospective, randomized trial. Circulation 1991;83:1179-1185
Web of Science | Medline

2
Carabello BA. Advances in the hemodynamic assessment of stenotic cardiac valves. J Am Coll Cardiol 1987;10:912-919
CrossRef | Web of Science | Medline

Author/Editor Response

We concur with Dr. Cheng that the introduction of the Inoue single-balloon technique should make the procedure of balloon mitral valvotomy more easily performed and thus more widely applied.

We cannot entirely agree with Dr. Chandra's statement that “regardless of the outcome of percutaneous mitral valvotomy, in the majority of patients, substantial tricuspid regurgitation does not decrease or resolve after the procedure.” In a recent study of 31 patients with tricuspid regurgitation who underwent mitral valvotomy, tricuspid regurgitation improved significantly in most of the patients.1 Although the improvement was greater if the right ventricular pressure exceeded 60 mm Hg, there was also substantial improvement in the patients with less severe pulmonary hypertension.

Finally, we were enlightened by Dr. Treasure's presentation of the history of closed surgical mitral commissurotomy. However, we would like to amend his account of the events of the late 1940s. In a paper presented to the American College of Surgeons in September 1947, Horace Smithy of the Medical College of South Carolina reported the use of a valvulotome in animal experiments. As a result of this presentation, a patient with severe mitral stenosis saw Smithy for an evaluation in January 1948. Smithy operated successfully on January 30, the patient made a full recovery, and her signs and symptoms of congestive heart failure resolved.2 The procedure antedated those of both Bailey and Harkin. Remarkably, at the time that Smithy performed his operation, he himself was already dying of rheumatic aortic stenosis. His hope was that Alfred Blalock would be willing to use the Smithy valvulotome to relieve Smithy's own stenosis. Blalock said that he would consider the surgery if Smithy could train him in the use of the instrument. Smithy and Blalock were to perform the surgery in a patient who had consented to the procedure, but unfortunately, the patient died from ventricular fibrillation during the induction of anesthesia. An opportunity for a second attempt never arose, and Smithy died on October 28, 1948.3

Blase A. Carabello, M.D.
Fred A. Crawford, M.D.
Medical University of South Carolina, Charleston, SC 29425

3 References

1
Skudicky D, Essop MR, Sareli P. Efficacy of mitral balloon valvotomy in reducing the severity of associated tricuspid valve regurgitation. Am J Cardiol 1994;73:209-211
CrossRef | Web of Science | Medline