Closed Mitral Valvotomy: Celebrating 100 Years of Surgical History

MBS

mitral valve stenosis

PBV

percutaneous balloon valvuloplasty

From both the available literature and his drawings, there is enough evidence that Leonardo da Vinci (1452–1519) knew very well the anatomy and physiology of the heart—and particularly the mitral valve apparatus. Such detailed studies were subsequently instrumental for further expanding knowledge of the heart and valvular diseases. More than a century later, mitral valve stenosis (MVS) was first described by John Mayow (1640–1679), an English pathologist, who observed an extreme constriction of the valve. Just a few years later, Giovan Battista Morgagni (1682–1771) confirmed this observation, defining the constriction as an ossification of the mitral valve.¹  In the years that followed, both the typical clinical pictures and the auscultatory findings of MVS were recognized, allowing physicians to reach a correct diagnosis in many cases.^2,3 

Soon thereafter, surgeons relived MVS in the anatomical theater by using commissural opening, advancing the hypothesis that surgical treatment of a stenotic mitral valve could be performed.^4–6  This procedure was effectively performed for the first time only 20 years after those initial assumptions. Undoubtedly, the operation dramatically changed the outlook for patients with MVS, giving them a new “lease on life.” This article presents a hundred-year-long journey from this historical undertaking.

The first closed-chest mitral valvotomy for MVS was performed by Elliott C. Cutler and Samuel A. Levine on May 20, 1923, at Brigham Hospital in Boston, Massachusetts.⁴  The patient was a 12-year-old girl who presented with exertional dyspnea and hematic sputum. The diagnosis was made on clinical grounds: “On auscultation the heart was found to be regular—126 to the minute. There was a moderate systolic murmur at the apex and a louder rumbling diastolic murmur, filling the entire diastole and ending with a presystolic accentuation and a somewhat snapping first heart sound.”⁴  Chest x-ray, electrocardiogram, and pulmonary function test results were also suggestive of MVS. Five days after the final diagnosis, the operation was performed. The approach was through a long median skin incision, followed by median sternotomy up to the second intercostal space. When the heart had been isolated, it was gently pulled upwards, and a valvotome was inserted into the left ventricular apex. Subsequently,

In reading the detailed description of the procedure, all the surgeon's uncertainty and anxiety can be appreciated. Because the heart proved to be particularly sensitive to manipulation, a desired repeat procedure was avoided.

The postoperative course was complicated by a right lung pneumonia, which completely resolved. Cardiac murmurs were still present but with reduced intensity, probably partly masked by pericardial effusion, which was left untreated. For this reason, the real efficacy of the operation and the clinical benefits could not be clearly assessed at that stage. The conclusions by the authors were extremely reasonable and fair:

The patient was discharged home in an improved condition, most likely with an unspecified degree of residual mitral regurgitation. She died from pneumonia 4.5 years later.⁵ 

Cutler's first mitral valvotomy was performed through the left ventricle using a valvotome, which was described as “an instrument somewhat similar to a tenotome or a slightly curved tonsil knife,” which had been used experimentally for the same procedure (Fig. 1).^4,5  Because Cutler referred to the instrument as a “knife” used to cut the mitral leaflets, it is likely that during such a blind operation, dilatation of the mitral valve was not directed to cut the commissures precisely for relief of the stenosis but involved the leaflets, as well, thus creating iatrogenic regurgitation. Indeed, other patients underwent the procedure using the same technique with disastrous results, dying in the first postoperative days because of massive mitral insufficiency.⁵ 

During the initial attempts to repair MVS in animals, Allen and Graham proposed the use of a cardioscope, a tubular instrument that could allow direct intracardiac vision; the procedure was well tolerated in dogs when the instrument was introduced through the left atrium, but it did not go beyond the experimental phase.⁶  On May 6, 1925, Henry S. Souttar performed the first digital mitral valve dilatation in a patient with concomitant regurgitation; because the mitral stenosis was moderate, with only a little leaflet thickening, the procedure was limited “to such dilatation as could be carried out by the finger.”⁷  In any case, Souttar demonstrated that by inserting a finger into the left atrium through the left atrial appendage, the mitral valve could be explored and dilated without the use of any cutting instrument and without disturbing the heart.⁸ 

As can be seen from both Cutler's and Souttar's papers, the term commissurotomy was never mentioned. Indeed, this term would be coined in 1948 by Charles P. Bailey, who performed what he considered the first modern corrective operation for mitral stenosis.^9,10  After some preliminary unsuccessful attempts, Bailey presented “the concept of separating the fused valve leaflets anatomically along the lines of the obliterated commissures,” thus relieving stenosis without creating regurgitation.¹⁰  For his first operation, he used a hooked knife attached to a finger to divide the fused commissures. Dwight E. Harken performed a similar operation in a 27-year-old man with mitral stenosis just 6 days after the 1 performed by Bailey; this timeline most likely contributed to the controversy over which surgeon was to be credited as the first to undertake that historic operation.¹¹  Controversy also exists on the better surgical approach for the treatment of MVS. Introducing an instrument through the left ventricular apex was in some cases difficult and could stimulate important arrhythmias, even causing cardiac arrest. The left atrium, accessed through a left thoracotomy, appeared a more favorable approach than the left ventricle because the atrium would be easier to manipulate. It could cause mobilization of thrombi, however, and tearing of a thin and fragile structure following atrial distention, with severe bleeding.¹⁰  In the same way, presence of a left atrial myxoma, misdiagnosed for mitral stenosis, could cause tumor embolization if a closed mitral commissurotomy had been attempted.¹² 

Contrary to the general attitude, Bailey proposed a right lateral approach to mitral commissurotomy.¹⁰  From the right side, the left atrium could be entered through the interatrial groove using a purse-string suture on the dissection line. The main advantage of the right-sided approach was considered to be the possibility of more easily reaching both mitral valve commissures. Indeed, as Bailey stated, in the majority of patients who had previously undergone an operation for MVS from the left, only the anterolateral commissure was separated.¹⁰  Because the anatomical orientation of the mitral valve through a right thoracotomy is different from that of a left-sided approach, however, one should be adequately prepared to face this new situation.¹⁰  From the right approach, it was more difficult to remove thrombi from the left atrium digitally; for this reason, an “aspirating tip” was introduced though the same incision to withdraw thrombotic material. In the first 200 patients undergoing the procedure from the right side, both mitral commissures were separated in 195 of them (97.5%), with an overall hospital mortality rate of 8%.¹⁰  Interestingly, others in the same time period used either the transatrial or transventricular approach to introduce an instrument that could produce a hole in the mitral valve, partially relieving stenosis without creating significant insufficiency.¹³ 

Regardless of surgical approach, the instruments used to relieve MVS have evolved. The knife Cutler used was ineffective and replaced by digital opening, referred to as “finger fracture” of the mitral commissures, performed for the first time in 1925.⁷  Subsequently, various instruments have been used. Harken et al¹⁴  in 1948 reported the use of a “cardiovalvulotome” similar to the 1 Cutler employed, introduced through the left atrium or 1 of the left pulmonary veins; the cutting edge of the instrument was not easy to manipulate, so after enlargement of the mitral orifice, a certain degree of “selective insufficiency” could be accepted. Bailey and Dryden P. Morse performed mitral commissurotomy using a guillotine knife,¹⁰  a device similar to that used by H.T. Nichols and W.L. Jamison in 1955 to treat subvalvular mitral stenosis.¹³  In many patients with MVS, particularly in those with long-standing disease, fusion of the subvalvular apparatus was frequently present that could not be treated using digital pressure only. In these patients, a modified guillotine knife with a blunt, golf club–angled lower end was used effectively.¹⁴  In Italy, Achille M. Dogliotti used a metallic ring inserted through the left atrium on the tip of the forefinger and provided with a scimitar blade that was directed toward the commissures. He used this technique on more than 2,500 patients with MVS.¹⁵ 

By the early 1950s, Charles Dubost in Paris had treated a series of 1,000 patients with MVS by using a dilator inserted through the left atrium.¹⁶  Based on this experience, a similar dilator was devised in 1954 by Oswald H. Tubbs that consisted of 2 flat handles that controlled the opening of the central blade and 2 lateral bars; when the handle was pushed, the dilator expanded up to 45 mm in width (Fig. 2A and 2B).¹⁷  This dilator was introduced through the left ventricular apex, guided into the mitral orifice by a finger inserted in the left atrial appendage, and progressively opened (Fig. 2C). There has been some controversy over the proper use of mechanical dilators, particularly on their correct orientation. For some surgeons, the orientation of the instrument was not relevant¹⁷ ; others recommended positioning the blades against the commissures,¹⁸  while still others preferred to open the dilator blades perpendicular to the midpoint of the leaflets.¹⁹  In any case, treatment of MVS with the Tubbs dilator provided results superior to those with digital valvotomy because the posteromedial commissure was difficult to reach and open adequately using either a bare finger or a knife.¹⁷  Contrary to the use of fingers, knives, or rings, with dilators, the commissures are not cut but torn and split; therefore, the term commissurotomy became inappropriate for this procedure (a still better term is commissural avulsion). The Tubbs dilator gained great popularity and was employed in many cases,^17–20  even with some modifications of the original instrument.²¹ 

A curved valvotome was used in 1948 by Russel C. Brock in London to treat pulmonary valve stenosis.²²  The same instrument was subsequently employed in patients with MVS,²³  at times used with scissors.²⁴  F.R. Edwards used a “mechanical splitter,” introduced through the left ventricle or the left atrium and oriented toward the commissures.²⁵  Others have devised a metal strip with a curved end, molded on the dorsum of the index finger; when the finger is flexed, the instrument presses each commissure, separating the mitral leaflets (Fig. 3).²⁶ 

After the advent of the heart-lung machine, relief of MVS by closed techniques became partly outdated. Starting in 1960,²⁷  open commissurotomy rapidly became the procedure of choice for the conservative treatment of MVS.^28–30  The evident advantages of an open over a closed technique were represented by the possibility of directly visualizing and inspecting the mitral valve to assess its suitability for commissurotomy. Furthermore, a better anatomical result could be obtained by cutting the commissures following the precise line of fusion (Fig. 4A) and by extending the repair to the subvalvular structures. The papillary muscles and fused chordae tendineae could be split (Fig. 4B), re-creating the interchordal spaces and increasing the mobility and area of the whole mitral valve apparatus. Finally, immediate assessment of the anatomical and functional result could be made. Visual inspection of the mitral valve has led to performing fewer commissurotomies than would have been done using a closed approach³¹ ; indeed, open repair yielded superior results in select patients with pure, severe, noncalcific MVS.³²  In addition, open mitral commissurotomy could be performed on valves with some degree of calcification, a contraindication to a closed procedure, thus avoiding prosthetic valve replacement. For these reasons, closed mitral commissurotomy was gradually abandoned in most centers.³³ 

The results of closed vs open mitral commissurotomy have been somewhat controversial. John et al³⁴  in 1983 published the largest series of patients undergoing closed mitral commissurotomy for MVS. During a 25-year interval, this procedure was performed in 3,724 consecutive patients, with an overall mortality rate under 4% and 84% survival at 24 years. In 1993, Scalia et al,³⁵  analyzing 280 patients over 20 years, concluded that open commissurotomy offered no better results than closed valvotomy in properly selected candidates. Detter et al³⁶  reported in 1999 their experience with closed and open mitral commissurotomy in 143 patients, showing excellent results up to 35 years and no significant differences between the 2 techniques. In 2015, Sherawat et al³⁷  reported a single-center experience with closed mitral valvotomy showing a 0.5% mortality rate and 75% freedom from reoperation at 20 years.

Percutaneous balloon valvuloplasty (PBV) was introduced by Inoue et al³⁸  in 1983; this less-invasive procedure received great support from the development of transesophageal echocardiography, which could more precisely define mitral valve anatomy, guide the balloon through the orifice, and allow immediate assessment of the results. In many centers, PBV has become the preferred treatment for MVS, particularly in carefully selected patients with tight MVS and commissural fusion with absent or minimal calcification. Percutaneous balloon valvuloplasty has been demonstrated to be safe and effective, providing clinical and hemodynamic improvement in patients with MVS. Immediate success is achieved when doubling of the mitral valve area occurs, obtaining an average of more than 2 cm² of the final mitral valve area.³⁹  Long-term results currently available indicate 98% and 87% survival at 9 and 12 years after PBV, respectively. The best results are obtained in young patients with sinus rhythm, no pulmonary hypertension, and no evidence of calcification of the mitral valve. In this subset, PBV appears to be superior to surgical commissurotomy.³⁹ 

The considerable reduction in the incidence of rheumatic disease and consequent valvular involvement has effectively eliminated closed mitral commissurotomy in the Western World and markedly reduced the open procedure, which not many years ago was still considered a “good operation.”³¹  For the same reason, closed mitral commissurotomy, like many old and seemingly useless procedures, regrettably is not taught anymore to young surgeons. In developing countries with limited financial resources and where rheumatic heart disease is still prevalent, however, closed mitral commissurotomy is often performed by skilled surgeons and has a definite role.³³  Ravikrishan et al,⁴⁰  comparing balloon with closed mitral valvuloplasty, have shown better results and particularly lower costs with such a surgical technique, even in recent years. Moreover, a reusable percutaneous mechanical dilator, using a transseptal approach and mimicking the Tubbs principle, was recently introduced as an alternative to the Inoue balloon, with considerable reduction in costs.⁴¹ 

Mitral valvotomy represents a milestone in the treatment of patients with MVS. This landmark operation has been subsequently replaced by increasingly more accurate closed and open procedures. Despite the excellent results reported with mitral commissurotomy, however, its role has been progressively limited by the reduction of rheumatic valve disease in the Western World and by the introduction of less-invasive, catheter-based procedures (Table I).^{1,4,7,9,17,27,38}  It took almost 50 years to introduce mitral valvotomy into clinical practice following the first suggestion that MVS could be relieved surgically, but as many developing countries have shown, mitral commissurotomy together with PBV remains a valid option for select patients. At present, because of the limited financial resources of countries where rheumatism is still endemic, both closed and open commissurotomies are still performed; indeed, they are considered valid and cost-effective options, especially in young patients with rheumatic MVS.³¹