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Closed mitral commissurotomy on cannulated pump stand-by through a sternal-split incision
Closed mitral commissurotomy on cannulated pump stand-by through a sternal-split incision An alternative to routine open commissurotomy A new technique---closed-cannulated commissurotomy-is presented as an alternative to open mitral commissurotomy. The procedure seems to incorporate the best features of both standard closed commissurotomy and open commissurotomy. In addition, the incidence of prosthetic valve replacement after this operation appears to be substantially less than after the open procedure.
Vincent L. Gott, M.D., Antonio Revilla, M.D. (by invitation), James S. Donahoo, M.D. (by invitation), Edward H. Klopp, B.S. (by invitation), and Robert K. Brawley, M.D. (by invitation), Baltimore, Md.
It
is generally agreed by many cardiac surgeons that the standard closed mitral commissurotomy procedure is an excellent operation for properly selected patients with noncalcific mitral stenosis. A number of surgeons, in fact, still employ the foregoing technique with pump stand-by as their primary approach to the problem of noncalcific mitral stenosis. There are some distinct disadvantages, however, with the standard closed mitral commissurotomy procedure, particularly when the patient has (1) an auricle too small for easy insertion of the index finger, (2) the unexpected finding of thrombus in the left atrium, or (3) valve pathology so severe that a prosthetic replacement is required. In each of these situations, it is necessary to convert the closedheart procedure to an open-heart operation, From the Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Md. 21205. Read at the Fifty-third Annual Meeting of The American Association for Thoracic Surgery, Dallas, Texas, April 16, 17, and 18, 1973.
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which is not always easy through a left thoracotomy. Therefore, more and more cardiac surgeons in this country are abandoning the standard closed commissurotomy in favor of routine open mitral commissurotomy through a median sternotomy. Open mitral commissurotomy provides two distinct advantages: First is the safety of having the patient on cardiopulmonary bypass for the procedure and second is the easy conversion to prosthetic replacement through the anterior approach. In most surgeon's hands, however, the incidence of mitral insufficiency and valve replacement is somewhat higher following the open procedure as compared to the closed procedure. In an effort to incorporate the safety and all the advantages of the open commissurotomy with the reduced incidence of prosthetic valve replacement that accompanies closed commissurotomy, a new operative approach to the problem of mitral stenosis has been employed in this institution since January, 1972.
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Fig. 1. Insertion of the modified Gerbode dilator into the left ventricle through the sternal-split incision.
Operative technique Following median sternotomy and opening of the pericardial sac, purse-string sutures are placed in the ascending aorta and right atrium for eventual cannulation of the aorta and venae cavae. A purse-string suture is placed in the left atrium just anterior to the right superior pulmonary vein; similarly, a mattress suture is placed in the apex of the left ventricle for insertion of the mechanical dilator (Fig. I) . In the early experience with this operative procedure, only the ascending aorta was cannulated and the pump oxygenator was used as an autotransfusing unit to return blood from the pericardial cavity. Currently, the ascending aorta and both cavae are cannulated, and partial cardiopulmonary bypass is employed during the commissurotomy. A disposable bubble oxygenator, primed with 1,500 c.c. of Ringer's lactate solution, is utilized for the procedure. With the patient on partial cardiopul-
monary bypass (caval tapes not occluded) , the index finger of the left hand is introduced into the left atrium and careful exploration is carried out for mural thrombi. If no thrombi are found, the mitral valve is palpated and evaluated with the index finger. The apex of the left ventricle is then tipped up and the dilator is inserted. The heart is returned to its normal position in the pericardial sac, and the dilator is guided into the valve orifice by the index finger in the left atrium . The dilator is then carefully opened to sequentially wider dimensions (Fig. 2). As the valve is dilated to a greater extent, the presence of regurgitant flow is monitored with the index finger above the valve. At the completion of the commissurotomy, the dilator is removed and the competency of the valve is carefully evaluated with the index finger. The mattress suture in the apex of the left ventricle and the purse-string suture in the left atrium are then tied.
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Fig. 2. With the heart in its normal position in the pericardial sac, the dilator is carefully opened. The index finger of the left hand guides the dilator through the mitral valve.
If the commissurotomy is initiated with the dilator but not completed to the mitral annulus, the atrium is opened and the valve procedure is completed under direct vision. Obviously, if thrombus is detected in the left atrium prior to commissurotomy or if a prosthetic valve is needed , the operation is converted to an open procedure. During the procedure, blood lost from the atriotomy or apical ventriculotomy is returned to the pump oxygenator by the cardiotomy sucker system. At the completion of circulatory support, most of.the blood in the oxygenator is slowly returned to the patient. At the time of the mitral valve dilatation, it is important to have the left ventricle in its normal position in the pericardial sac, with the monitor showing that a good pulsatile flow is being developed by the actively contracting left ventricle. When the standard Gerbode dilator is used through a sternal-
split incision, there is considerable dislocation of the heart. Therefore, this dilator has been modified (Fig. 3) so that the horizontal section is only 9 em. in length, thus allowing the heart to be in its normal position in the pericardial sac when the dilator is opened. This modified dilator also has calibrations on the handle so that the spread of the blades can be determined without removing the instrument from the left ventricle.* Clinical material
Since January, 1972, all patients at this institution who had mitral stenosis and some degree of mobility of the mitral valve as demonstrated by cardiac catheterization have been submitted to this newer procedure. 'The Gerbode dilator was originally modified in the Instrumen t Development Labo ratory. Department of Surgery, The Johns Hopkins H ospital. It is now commercially available from Cod man , Inc., Randolf, Mass .
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Fig. 3. A . The modified Gerbode dilator with a short horizontal limb to allow for repositioning of heart in pericardial sac during dilatation. B, Standard Gerbode dilator.
Table I. Vessel cannulation and pump support combinations for cannulated-closed commissurotomy Group No. 1 2 3 4
Arterial cannulation Ascending Ascending Ascending Ascending
aorta aorta aorta aorta
Venous cannulation
Pump support
None Cavae Cavae Cavae
None None Partial Total
Use of pump oxygenator Autotransfuser Autotransfuser Circulatory support Cardiopulmonary bypass (open-heart)
No. of patients 3 16 8 7*
'This group was composed of 6 patients from Group 2 and 1 patient from Group 3.
Twenty-seven patients have been operated upon with this technique, which is called the cannulated-closed commissurotomy. Various combinations of vessel cannulation and pump support have been used for these 27 patients (Table I). Three of the patients operated upon early in the series underwent closed commissurotomy with only the ascending aorta cannulated and the pump oxygenator used as an autotransfusing unit. Sixteen patients had aortic and caval cannulation with the pump oxygenator used as an autotransfuser during the closed commissurotomy (technique 2). In 4 of these 16 patients, total cardiopulmonary bypass
was then employed to permit open examination of the valve after the closed commissurotomy. In 2 other patients in Group 2, an initial attempt at closed dilatation was converted to an open procedure. One of these patients (M . G.) had completion of the commissurotomy under direct vision and the second patient (1. G.) had replacement of a badly diseased valve with a Starr-Edwards prosthesis. The last 8 patients in the series underwent cannulated-closed commissurotomy with partial pump support. In 1 of these patients (A. R.) , the closed technique was then converted to an open-heart procedure
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Table II. Results with cannulated-closed commissurotomy (27 patients)" Severity oj valve pathology A B
C
Satisjactory No. oj commis- Prosthetic Deaths patients surotomy valve 10 14t 3
10 13 2
o o o
'Three patients also had aortic valve replacement, and I patient also had coronary artery bypass. tNine patients had calcified valves.
for completion of the commissurotomy under direct vision. All of the combinations indicated in Table I have worked very satisfactorily, but partial circulatory support is currently preferred during the time that the mitral commissurotomy is performed. Three patients had aortic valve replacement and 1 patient had a vein bypass as concomitant procedures with the cannulatedclosed commissurotomy. In each of these 4 patients the commissurotomy was performed first and then the associated procedure was carried out with total cardiopulmonary bypass. Results The results obtained in the 27 patients undergoing cannulated-closed commissurotomy are depicted in Table II. The severity of the mitral valve pathology is indicated: In this grading scheme, an A valve is a pliable valve without calcium, a C valve is a severely diseased valve with a considerable amount of calcium in the commissures and leaflets, and a B valve is an intermediate valve which has more fibrous thickening than the A valve and may have minimal-to-moderate calcium. As is noted in Table II, 10 of the patients had very pliable valves, 14 patients had intermediate valves (9 with calcium), and 3 of the patients had more severely diseased valves (C valves) . Satisfactory commissurotomy was achieved in all 10 patients with an A valve. Two of the patients in this group with A valves had had closed commissurotomies 5 and 7 years
earlier and obtained a good result with the cannulated-closed procedure. Thirteen of the 14 patients with B valves obtained a satisfactory commissurotomy. In 11 cases this could be achieved with the cannulated-closed technique, while in 2 patients the commissurotomy was initiated with this technique and then completed satisfactorily under direct vision. One patient with a B valve was left with 1+ insufficiency. This patient was treated early in the operative series, and the valve was examined under direct vision after the closed commissurotomy. Although the leaflets were fairly thickened and fibrotic, it was felt that an adequate result had been obtained. This patient subsequently developed 2+ mitral insufficiency and, over the next 10 months, developed severe tricuspid insufficiency. One year after the original procedure, the patient underwent reoperation, and both the mitral and tricuspid valves were replaced. The mitral valve pathology had changed only minimally during the 1 year interval, but, there were several ruptured chordae tendineae of the tricuspid valve. The disease process resulting in these ruptured chordae was unclear. It was anticipated from preoperative catheterization findings that all 3 of the patients with C valves would require replacement. Gratifying results were obtained, however, in 2 of these patients, 1 of whom had had a commissurotomy 8 years earlier. The third patient, who had had a commissurotomy 2 years earlier, had such severe calcification that prosthetic replacement was required. There were no deaths in the over-all series of 27 patients, and morbidity was limited to 2 cases. The first patient (discussed above) developed 1+ mitral insufficiency at the time of the closed commissurotomy and required both a tricuspid and mitral valve replacement 1 year later. In the second case (second patient in the series), the closed commissurotomy was carried out before the left atrial wall was palpated for thrombus. An embolus occurred from a ball thrombus to both common femoral vessels. This was
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recognized at the time of the operation, and these emboli were extracted with no further problems. It it obviously important to palpate carefully the walls of the left atrium for thrombus prior to performing the commissurotomy. If thrombus is detected, it is very easy through this anterior approach to convert to an open-heart procedure and remove the thrombus. The 4 patients who had concomitant cardiac procedures (aortic valve replacement in 3 and saphenous vein bypass in 1) all obtained very satisfactory results. Discussion
During the past 23 years, the procedure of choice at this institution for most patients with noncalcific mitral stenosis has been closed mitral commissurotomy. The first of these operations was performed at The Johns Hopkins Hospital by Mr. Russell Brock (now Lord Brock) on Nov. 17, 1949. Subsequently, 632 patients have undergone closed mitral commissurotomy through the left chest. Prior to 1960, the finger-fracture technique was ordinarily used, and after this date the Gerbode dilator was employed. Also, during this same period that the dilator has been used in closed procedures, patients with mitral stenosis who appeared to have a less pliable valve and more calcium on cardiac catheterization have been submitted to open mitral commissurotomy. In examining the results with closed and open commissurotomy in this institution, we have been impressed with the higher incidence of mitral insufficiency in those patients undergoing open commissurotomy. Evaluation of the results of these two procedures at this institution over the last 7 years clearly supports this impression. In a consecutive series of 88 patients undergoing standard closed commissurotomy at The Johns Hopkins Hospital from 1965 through 1971, there were only 6 patients who developed postoperative mitral insufficiency, and 3 of these required a prosthesis. There were two deaths, one occurring as a result of myocardial infarction 24 hours after sue-
cessful commissurotomy and the second death occurring after the placement of a prosthetic valve. During this same 7 year period, 25 patients were taken to the operating room for an open commissurotomy. After the mitral valve had been visualized, 4 patients were judged to need a prosthesis, and these patients all did well. Twenty-one patients had open commissurotomy and 12 developed mitral insufficiency. Ten of these 12 patients had a prosthetic valve inserted, and all 10 have done well. Of the 2 patients with mitral insufficiency who did not have a valve placed, 1 subsequently died of congestive failure. This patient, who should have had a prosthetic valve, was the only one to die in the group of 25 patients taken to the operating room for an open commissurotomy. It is true that, for the most part, patients submitted to open commissurotomy had less pliable valves with more calcium than those submitted to closed commissurotomy. Nevertheless, in the case of some with more pliable valves who developed insufficiency after open commissurotomy, it was felt that a better result could have been achieved had the procedure been performed in the closed heart. The twenty-one open commissurotomies were performed by a number of different resident and staff surgeons over the 7 year period, and the technique of choice was direct incision when the commissures could be well visualized. More often than not, there was fibrous obliteration of the commissures and the Gerbode dilator was inserted through the atriotomy to try to initiate the split in the commissures. With the dilator used in this way, there was a surprising incidence of lacerations in the free margin of the valve leaflets with resulting insufficiency. Our own experience with closed and open commissurotomy clearly suggested that, given comparable stenotic mitral valves, there is a lower incidence of insufficiency when the procedure is performed in the closed, beating heart as opposed to the open, flaccid heart. The difference seemed to be
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Valve seen from below
Fig. 4. Schematic diagram of tension lines that appear to be applied to mitral valve by dilator in (A) the open, flaccid heart and (B) the closed, beating heart. (See text for details.)
particularly striking when the commissurotomies (both open and closed) were performed with the Gerbode dilator. In order to explain these observations on a physical basis, an effort was made to understand the stresses to which the valve leaflets are subjected during commissurotomy. Clearly, there are two sources of stress on the leaflets which must be considered: (l) stress imposed by the dilator and (2) stress from additional forces, such as tension in the chordae tendineae. The force applied by the dilator is distributed equally around the entire 360 degrees of the valve orifice. Hence, if no other forces are acting on the valve, the orifice will tear at its weakest point. Such is the case in the open commissurotomy, in that the only stress applied to the valve is that imposed by the dilator (Fig. 4, A); if the valve splits at the commissures, this simply is a result of weaker tissue in this area. This, of course, is not always the case. In the closed or cannulated-closed procedure, both the stress due to the dilator and additional stress imposed by effective ventricular contraction are present. The dilator forces again act around the entire margin of the orifice, but the stresses added by effective ventricular contraction are applied
near the commissures. Systolic ventricular pressure is exerted against the valve, and the forces generated are transmitted to the chordae tendineae (as shown in Fig. 4, B). Hence, with the closed operation, the stresses consist of those applied by the dilator (circumferential) plus those applied locally at the commissures by the chordae tendineae. The tension applied across the fused commissures is then greater than that applied to the free margin of the leaflets. In addition, in the beating heart the lateral pressure against the valve leaflets imposed by intraventricular blood may distribute the tension of the dilator over a larger area of the leaflets, rather than just along the free margin of the leaflet. Clearly, the explanation offered above is an unproved hypothesis. Neither experimental data nor firm calculations of the magnitude of forces acting on the valve have been demonstrated. However, it is clear from mathematical calculations that the forces imposed by the dilator in the open procedure do act equally around the entire valve orifice. Further, the clinical results at this institution along with those reported by others support this hypothesis. Precise information on the incidence of valve replacement in routine open commissurotomy is almost impossible to obtain from the literature. Most reports supporting the open technique do not include those patients who had mitral replacement after an attempted open commissurotomy. Messmer and associates' have reported a series of 100 consecutive cases of open mitral commissurotomy with no deaths. They state that the complications in this series of patients were minimal; however, it was not indicated how many patients at the same time underwent open commissurotomy and, in turn, then required valve replacement because of the development of mitral insufficiency. Robinson and Atti" also reported on a group of 103 patients with predominant mitral stenosis who were operated upon with open cardiotomy. The authors indicated that the patients with mitral insufficiency or with severely diseased stenotic
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valves requiring prosthetic replacements are not included in this report. They reported that satisfactory incisional commissurotomy was carried out in 96 of the 103 patients, and in only seven instances was a suboptimal anatomic result obtained. The authors indicated that no patient was left with hemodynamically significant mitral insufficiency. There were only two early deaths and one late death, 35 days after surgery, for a total mortality rate of 2.9 per cent in this excellent series. Again, it is not apparent how many valves with significant stenotic disease were replaced during the same time period. Roe and associates," on the other hand, have reported their experience with routine open commissurotomy in which the incidence of insufficiency and valve replacement was thoroughly documented. These authors reported a 5 year experience with routine open commissurotomy in 95 patients. Replacement with a prosthesis was required in 42 of these patients (44 per cent), and in 15 additional cases (15 per cent) "iatrogenic incompetence" had to be corrected with the placement of sutures in the commissures. Therefore, 59 per cent of the patients undergoing routine open commissurotomy in this series had insufficiency corrected by suture repair or prosthetic replacement. Turina and associates- have presented strong arguments favoring the standard closed commissurotomy over routine open commissurotomy with the specific advantage being the lower incidence of valve replacement with the closed procedure. These authors reported their late follow-up in 137 patients with mitral stenosis who were operated upon by means of the closed technique with the transventricular dilator. Valve calcification was present in 38 of the 137 patients, and they pointed out that calcification or slight-to-moderate mitral insufficiency in patients with predominant mitral stenosis did not preclude success of the closed mitral commissurotomy. The early mortality rate was 1.5 per cent and the late mortality rate was 3.7 per cent. Reoperation was performed in only 1 patient 5 years
after commissurotomy for calcified mitral valve disease. Turina and his colleagues" stressed that the hemodynamic performance of the mitral valve before, during, and after commissurotomy can be judged only when the procedure is done in the closed, beating heart. They also indicated that the temptation to replace a grossly diseased but functionally competent valve is much greater in the open procedure. These authors feel that standard closed commissurotomy still has its place, not because of better anatomic or functional results but because many mitral valves can be preserved for several more years. A number of additional reports have presented very optimistic late follow-up data on the use of the standard closed commissurotomy procedure. Olinger and associates" reviewed the long-term (1.5 to 14 years; average of 5.5 years) follow-up of 23 patients selected for presentation because they all had moderate-to-severe mitral valve calcification and were submitted to closed commissurotomy. In this group of patients with severe mitral pathology, there was an increase in regurgitation in only 1 patient. There were no operative deaths and six late deaths; 4 patients developed restenosis. Olinger's group" concluded that the late results of closed commissurotomy, even in significantly calcified valves, are quite encouraging and that if these badly diseased valves can be made to function by commissurotomy, the immediate and long-term results are superior to those achieved by a prosthetic valve. Another excellent long-term follow-up on closed commissurotomy was recently presented by Nathaniels and associates" from the Massachusetts General Hospital. These authors reported on a series of 100 consecutive patients who survived closed mitral valvuloplasty between June, 1952, and January, 1955. They were then studied 15 years later. Accurate information was obtained on 88 of the 100 patients. Of 88 patients, 47 per cent were alive and 27 per cent had undergone no further procedure to the mitral valve. Fifteen per cent could
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be classified as in clinically satisfactory condition more than 15 years after surgery. These recent reports in the literature tend to corroborate the value of closed commissurotomy even in patients with moderately calcified valves. The long-term results of closed mitral commissurotomy in the reports by Turina,' Olinger, 5 Nathaniels," and others are certainly very encouraging. We feel that the standard closed commissurotomy does offer some specific advantages (continuous monitoring for mitral insufficiency and the possible engineering advantage of using a tethered valve), and these can be combined with the advantages of the standard open commissurotomy (safety of the pump oxygenator, the anterior approach, and easy conversion to prosthetic replacement) in the newer cannulated-closed commissurotomy. In addition, this operation seems to provide a very simple and satisfactory method for achieving a commissurotomy in a patient undergoing coronary artery bypass or aortic valve replacement, as well as the patient who has had a previous commissurotomy.
nary artery bypass or aortic valve replacement. In addition, it seems to be a valuable procedure for those patients who have undergone previous closed commissurotomy. 3. This procedure has been used routinely at this institution for the past 15 months in all patients with a moderately mobile, stenotic mitral valve. Twenty-seven patients (12 with calcium) have undergone an attempted commissurotomy with this technique. One patient with a badly diseased valve required a mitral prosthesis, and 1 patient with 1+ mitral insufficiency at the completion of the closed commissurotomy required mitral and tricuspid valve replacement 1 year later. All of the remaining 25 patients obtained satisfactory commissurotomies. 4. The cannulated-closed commissurotomy not only seems to incorporate the safety and all of the advantages of the standard open commissurotomy but also appears to reduce significantly the incidence of prosthetic valve replacement when compared to the open procedure.
Conclusions 1. It is felt that closed mitral commissurotomy through a sternal-split incision on pump stand-by, with the ascending aorta and both cavae cannulated, is an improved alternative to routine open mitral commissurotomy. This operation appears to combine the best features of the standard closed commissurotomy (the ability to monitor the mitral valve continuously for insufficiency and the possible engineering advantage of performing the commissurotomy on a tethered valve) with the advantages of open commissurotomy (safety of the pump oxygenator, anterior approach, and easy conversion to prosthetic replacement). 2. This operation offers a very simple and satisfactory method for performing a commissurotomy in combination with coro-
2 3 4
5
6
REFERENCES Messmer, S. G., Hallman, R., and Cooley, D. A.: Open Mitral Commissurotomy: Results of 100 Consecutive Cases, J. THORAC. CARDIOVASC. SURG. 62: 366, 1971. Robinson, G., and Atti, L.: Elective Open-Heart Surgery for Mitral Stenosis, Ann. Thorac. Surg. 6: 246, 1968. Roe, B. B., Edmunds, L. H., Jr., Fishman, N. H., and Hutchinson, J. C.: Open Mitral Valvulotomy, Ann. Thorac. Surg. 12: 483, 1971. Turina, M., Messmer, B. J., and Senning, A.: Closed Mitral Commissurotomy: Operative Resuits in Late Follow-Up in 137 Patients, Surgery 72: 812, 1972. Olinger, G. N., Rio, F. W., and Maloney, J. D.: Closed Valvulotomy for Calcific Mitral Stenosis, 1. THoRAc. CARDIOVASC. SURG. 62: 357, 1971. Nathaniels, E. K., Moncure, A. C., and Scannell, J. G.: A 15-Year Follow-Up of Closed Mitral Valvuloplasty, Ann. Thorac. Surg. 10: 27, 1970. (For Discussion, see page 80)
Vincent L. Gott, M.D., Antonio Revilla, M.D. (by invitation), James S. Donahoo, M.D. (by invitation), Edward H. Klopp, B.S. (by invitation), and Robert K. Brawley, M.D. (by invitation), Baltimore, Md.
It
is generally agreed by many cardiac surgeons that the standard closed mitral commissurotomy procedure is an excellent operation for properly selected patients with noncalcific mitral stenosis. A number of surgeons, in fact, still employ the foregoing technique with pump stand-by as their primary approach to the problem of noncalcific mitral stenosis. There are some distinct disadvantages, however, with the standard closed mitral commissurotomy procedure, particularly when the patient has (1) an auricle too small for easy insertion of the index finger, (2) the unexpected finding of thrombus in the left atrium, or (3) valve pathology so severe that a prosthetic replacement is required. In each of these situations, it is necessary to convert the closedheart procedure to an open-heart operation, From the Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Md. 21205. Read at the Fifty-third Annual Meeting of The American Association for Thoracic Surgery, Dallas, Texas, April 16, 17, and 18, 1973.
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which is not always easy through a left thoracotomy. Therefore, more and more cardiac surgeons in this country are abandoning the standard closed commissurotomy in favor of routine open mitral commissurotomy through a median sternotomy. Open mitral commissurotomy provides two distinct advantages: First is the safety of having the patient on cardiopulmonary bypass for the procedure and second is the easy conversion to prosthetic replacement through the anterior approach. In most surgeon's hands, however, the incidence of mitral insufficiency and valve replacement is somewhat higher following the open procedure as compared to the closed procedure. In an effort to incorporate the safety and all the advantages of the open commissurotomy with the reduced incidence of prosthetic valve replacement that accompanies closed commissurotomy, a new operative approach to the problem of mitral stenosis has been employed in this institution since January, 1972.
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Fig. 1. Insertion of the modified Gerbode dilator into the left ventricle through the sternal-split incision.
Operative technique Following median sternotomy and opening of the pericardial sac, purse-string sutures are placed in the ascending aorta and right atrium for eventual cannulation of the aorta and venae cavae. A purse-string suture is placed in the left atrium just anterior to the right superior pulmonary vein; similarly, a mattress suture is placed in the apex of the left ventricle for insertion of the mechanical dilator (Fig. I) . In the early experience with this operative procedure, only the ascending aorta was cannulated and the pump oxygenator was used as an autotransfusing unit to return blood from the pericardial cavity. Currently, the ascending aorta and both cavae are cannulated, and partial cardiopulmonary bypass is employed during the commissurotomy. A disposable bubble oxygenator, primed with 1,500 c.c. of Ringer's lactate solution, is utilized for the procedure. With the patient on partial cardiopul-
monary bypass (caval tapes not occluded) , the index finger of the left hand is introduced into the left atrium and careful exploration is carried out for mural thrombi. If no thrombi are found, the mitral valve is palpated and evaluated with the index finger. The apex of the left ventricle is then tipped up and the dilator is inserted. The heart is returned to its normal position in the pericardial sac, and the dilator is guided into the valve orifice by the index finger in the left atrium . The dilator is then carefully opened to sequentially wider dimensions (Fig. 2). As the valve is dilated to a greater extent, the presence of regurgitant flow is monitored with the index finger above the valve. At the completion of the commissurotomy, the dilator is removed and the competency of the valve is carefully evaluated with the index finger. The mattress suture in the apex of the left ventricle and the purse-string suture in the left atrium are then tied.
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Fig. 2. With the heart in its normal position in the pericardial sac, the dilator is carefully opened. The index finger of the left hand guides the dilator through the mitral valve.
If the commissurotomy is initiated with the dilator but not completed to the mitral annulus, the atrium is opened and the valve procedure is completed under direct vision. Obviously, if thrombus is detected in the left atrium prior to commissurotomy or if a prosthetic valve is needed , the operation is converted to an open procedure. During the procedure, blood lost from the atriotomy or apical ventriculotomy is returned to the pump oxygenator by the cardiotomy sucker system. At the completion of circulatory support, most of.the blood in the oxygenator is slowly returned to the patient. At the time of the mitral valve dilatation, it is important to have the left ventricle in its normal position in the pericardial sac, with the monitor showing that a good pulsatile flow is being developed by the actively contracting left ventricle. When the standard Gerbode dilator is used through a sternal-
split incision, there is considerable dislocation of the heart. Therefore, this dilator has been modified (Fig. 3) so that the horizontal section is only 9 em. in length, thus allowing the heart to be in its normal position in the pericardial sac when the dilator is opened. This modified dilator also has calibrations on the handle so that the spread of the blades can be determined without removing the instrument from the left ventricle.* Clinical material
Since January, 1972, all patients at this institution who had mitral stenosis and some degree of mobility of the mitral valve as demonstrated by cardiac catheterization have been submitted to this newer procedure. 'The Gerbode dilator was originally modified in the Instrumen t Development Labo ratory. Department of Surgery, The Johns Hopkins H ospital. It is now commercially available from Cod man , Inc., Randolf, Mass .
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Fig. 3. A . The modified Gerbode dilator with a short horizontal limb to allow for repositioning of heart in pericardial sac during dilatation. B, Standard Gerbode dilator.
Table I. Vessel cannulation and pump support combinations for cannulated-closed commissurotomy Group No. 1 2 3 4
Arterial cannulation Ascending Ascending Ascending Ascending
aorta aorta aorta aorta
Venous cannulation
Pump support
None Cavae Cavae Cavae
None None Partial Total
Use of pump oxygenator Autotransfuser Autotransfuser Circulatory support Cardiopulmonary bypass (open-heart)
No. of patients 3 16 8 7*
'This group was composed of 6 patients from Group 2 and 1 patient from Group 3.
Twenty-seven patients have been operated upon with this technique, which is called the cannulated-closed commissurotomy. Various combinations of vessel cannulation and pump support have been used for these 27 patients (Table I). Three of the patients operated upon early in the series underwent closed commissurotomy with only the ascending aorta cannulated and the pump oxygenator used as an autotransfusing unit. Sixteen patients had aortic and caval cannulation with the pump oxygenator used as an autotransfuser during the closed commissurotomy (technique 2). In 4 of these 16 patients, total cardiopulmonary bypass
was then employed to permit open examination of the valve after the closed commissurotomy. In 2 other patients in Group 2, an initial attempt at closed dilatation was converted to an open procedure. One of these patients (M . G.) had completion of the commissurotomy under direct vision and the second patient (1. G.) had replacement of a badly diseased valve with a Starr-Edwards prosthesis. The last 8 patients in the series underwent cannulated-closed commissurotomy with partial pump support. In 1 of these patients (A. R.) , the closed technique was then converted to an open-heart procedure
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Table II. Results with cannulated-closed commissurotomy (27 patients)" Severity oj valve pathology A B
C
Satisjactory No. oj commis- Prosthetic Deaths patients surotomy valve 10 14t 3
10 13 2
o o o
'Three patients also had aortic valve replacement, and I patient also had coronary artery bypass. tNine patients had calcified valves.
for completion of the commissurotomy under direct vision. All of the combinations indicated in Table I have worked very satisfactorily, but partial circulatory support is currently preferred during the time that the mitral commissurotomy is performed. Three patients had aortic valve replacement and 1 patient had a vein bypass as concomitant procedures with the cannulatedclosed commissurotomy. In each of these 4 patients the commissurotomy was performed first and then the associated procedure was carried out with total cardiopulmonary bypass. Results The results obtained in the 27 patients undergoing cannulated-closed commissurotomy are depicted in Table II. The severity of the mitral valve pathology is indicated: In this grading scheme, an A valve is a pliable valve without calcium, a C valve is a severely diseased valve with a considerable amount of calcium in the commissures and leaflets, and a B valve is an intermediate valve which has more fibrous thickening than the A valve and may have minimal-to-moderate calcium. As is noted in Table II, 10 of the patients had very pliable valves, 14 patients had intermediate valves (9 with calcium), and 3 of the patients had more severely diseased valves (C valves) . Satisfactory commissurotomy was achieved in all 10 patients with an A valve. Two of the patients in this group with A valves had had closed commissurotomies 5 and 7 years
earlier and obtained a good result with the cannulated-closed procedure. Thirteen of the 14 patients with B valves obtained a satisfactory commissurotomy. In 11 cases this could be achieved with the cannulated-closed technique, while in 2 patients the commissurotomy was initiated with this technique and then completed satisfactorily under direct vision. One patient with a B valve was left with 1+ insufficiency. This patient was treated early in the operative series, and the valve was examined under direct vision after the closed commissurotomy. Although the leaflets were fairly thickened and fibrotic, it was felt that an adequate result had been obtained. This patient subsequently developed 2+ mitral insufficiency and, over the next 10 months, developed severe tricuspid insufficiency. One year after the original procedure, the patient underwent reoperation, and both the mitral and tricuspid valves were replaced. The mitral valve pathology had changed only minimally during the 1 year interval, but, there were several ruptured chordae tendineae of the tricuspid valve. The disease process resulting in these ruptured chordae was unclear. It was anticipated from preoperative catheterization findings that all 3 of the patients with C valves would require replacement. Gratifying results were obtained, however, in 2 of these patients, 1 of whom had had a commissurotomy 8 years earlier. The third patient, who had had a commissurotomy 2 years earlier, had such severe calcification that prosthetic replacement was required. There were no deaths in the over-all series of 27 patients, and morbidity was limited to 2 cases. The first patient (discussed above) developed 1+ mitral insufficiency at the time of the closed commissurotomy and required both a tricuspid and mitral valve replacement 1 year later. In the second case (second patient in the series), the closed commissurotomy was carried out before the left atrial wall was palpated for thrombus. An embolus occurred from a ball thrombus to both common femoral vessels. This was
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recognized at the time of the operation, and these emboli were extracted with no further problems. It it obviously important to palpate carefully the walls of the left atrium for thrombus prior to performing the commissurotomy. If thrombus is detected, it is very easy through this anterior approach to convert to an open-heart procedure and remove the thrombus. The 4 patients who had concomitant cardiac procedures (aortic valve replacement in 3 and saphenous vein bypass in 1) all obtained very satisfactory results. Discussion
During the past 23 years, the procedure of choice at this institution for most patients with noncalcific mitral stenosis has been closed mitral commissurotomy. The first of these operations was performed at The Johns Hopkins Hospital by Mr. Russell Brock (now Lord Brock) on Nov. 17, 1949. Subsequently, 632 patients have undergone closed mitral commissurotomy through the left chest. Prior to 1960, the finger-fracture technique was ordinarily used, and after this date the Gerbode dilator was employed. Also, during this same period that the dilator has been used in closed procedures, patients with mitral stenosis who appeared to have a less pliable valve and more calcium on cardiac catheterization have been submitted to open mitral commissurotomy. In examining the results with closed and open commissurotomy in this institution, we have been impressed with the higher incidence of mitral insufficiency in those patients undergoing open commissurotomy. Evaluation of the results of these two procedures at this institution over the last 7 years clearly supports this impression. In a consecutive series of 88 patients undergoing standard closed commissurotomy at The Johns Hopkins Hospital from 1965 through 1971, there were only 6 patients who developed postoperative mitral insufficiency, and 3 of these required a prosthesis. There were two deaths, one occurring as a result of myocardial infarction 24 hours after sue-
cessful commissurotomy and the second death occurring after the placement of a prosthetic valve. During this same 7 year period, 25 patients were taken to the operating room for an open commissurotomy. After the mitral valve had been visualized, 4 patients were judged to need a prosthesis, and these patients all did well. Twenty-one patients had open commissurotomy and 12 developed mitral insufficiency. Ten of these 12 patients had a prosthetic valve inserted, and all 10 have done well. Of the 2 patients with mitral insufficiency who did not have a valve placed, 1 subsequently died of congestive failure. This patient, who should have had a prosthetic valve, was the only one to die in the group of 25 patients taken to the operating room for an open commissurotomy. It is true that, for the most part, patients submitted to open commissurotomy had less pliable valves with more calcium than those submitted to closed commissurotomy. Nevertheless, in the case of some with more pliable valves who developed insufficiency after open commissurotomy, it was felt that a better result could have been achieved had the procedure been performed in the closed heart. The twenty-one open commissurotomies were performed by a number of different resident and staff surgeons over the 7 year period, and the technique of choice was direct incision when the commissures could be well visualized. More often than not, there was fibrous obliteration of the commissures and the Gerbode dilator was inserted through the atriotomy to try to initiate the split in the commissures. With the dilator used in this way, there was a surprising incidence of lacerations in the free margin of the valve leaflets with resulting insufficiency. Our own experience with closed and open commissurotomy clearly suggested that, given comparable stenotic mitral valves, there is a lower incidence of insufficiency when the procedure is performed in the closed, beating heart as opposed to the open, flaccid heart. The difference seemed to be
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Valve seen from below
Fig. 4. Schematic diagram of tension lines that appear to be applied to mitral valve by dilator in (A) the open, flaccid heart and (B) the closed, beating heart. (See text for details.)
particularly striking when the commissurotomies (both open and closed) were performed with the Gerbode dilator. In order to explain these observations on a physical basis, an effort was made to understand the stresses to which the valve leaflets are subjected during commissurotomy. Clearly, there are two sources of stress on the leaflets which must be considered: (l) stress imposed by the dilator and (2) stress from additional forces, such as tension in the chordae tendineae. The force applied by the dilator is distributed equally around the entire 360 degrees of the valve orifice. Hence, if no other forces are acting on the valve, the orifice will tear at its weakest point. Such is the case in the open commissurotomy, in that the only stress applied to the valve is that imposed by the dilator (Fig. 4, A); if the valve splits at the commissures, this simply is a result of weaker tissue in this area. This, of course, is not always the case. In the closed or cannulated-closed procedure, both the stress due to the dilator and additional stress imposed by effective ventricular contraction are present. The dilator forces again act around the entire margin of the orifice, but the stresses added by effective ventricular contraction are applied
near the commissures. Systolic ventricular pressure is exerted against the valve, and the forces generated are transmitted to the chordae tendineae (as shown in Fig. 4, B). Hence, with the closed operation, the stresses consist of those applied by the dilator (circumferential) plus those applied locally at the commissures by the chordae tendineae. The tension applied across the fused commissures is then greater than that applied to the free margin of the leaflets. In addition, in the beating heart the lateral pressure against the valve leaflets imposed by intraventricular blood may distribute the tension of the dilator over a larger area of the leaflets, rather than just along the free margin of the leaflet. Clearly, the explanation offered above is an unproved hypothesis. Neither experimental data nor firm calculations of the magnitude of forces acting on the valve have been demonstrated. However, it is clear from mathematical calculations that the forces imposed by the dilator in the open procedure do act equally around the entire valve orifice. Further, the clinical results at this institution along with those reported by others support this hypothesis. Precise information on the incidence of valve replacement in routine open commissurotomy is almost impossible to obtain from the literature. Most reports supporting the open technique do not include those patients who had mitral replacement after an attempted open commissurotomy. Messmer and associates' have reported a series of 100 consecutive cases of open mitral commissurotomy with no deaths. They state that the complications in this series of patients were minimal; however, it was not indicated how many patients at the same time underwent open commissurotomy and, in turn, then required valve replacement because of the development of mitral insufficiency. Robinson and Atti" also reported on a group of 103 patients with predominant mitral stenosis who were operated upon with open cardiotomy. The authors indicated that the patients with mitral insufficiency or with severely diseased stenotic
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valves requiring prosthetic replacements are not included in this report. They reported that satisfactory incisional commissurotomy was carried out in 96 of the 103 patients, and in only seven instances was a suboptimal anatomic result obtained. The authors indicated that no patient was left with hemodynamically significant mitral insufficiency. There were only two early deaths and one late death, 35 days after surgery, for a total mortality rate of 2.9 per cent in this excellent series. Again, it is not apparent how many valves with significant stenotic disease were replaced during the same time period. Roe and associates," on the other hand, have reported their experience with routine open commissurotomy in which the incidence of insufficiency and valve replacement was thoroughly documented. These authors reported a 5 year experience with routine open commissurotomy in 95 patients. Replacement with a prosthesis was required in 42 of these patients (44 per cent), and in 15 additional cases (15 per cent) "iatrogenic incompetence" had to be corrected with the placement of sutures in the commissures. Therefore, 59 per cent of the patients undergoing routine open commissurotomy in this series had insufficiency corrected by suture repair or prosthetic replacement. Turina and associates- have presented strong arguments favoring the standard closed commissurotomy over routine open commissurotomy with the specific advantage being the lower incidence of valve replacement with the closed procedure. These authors reported their late follow-up in 137 patients with mitral stenosis who were operated upon by means of the closed technique with the transventricular dilator. Valve calcification was present in 38 of the 137 patients, and they pointed out that calcification or slight-to-moderate mitral insufficiency in patients with predominant mitral stenosis did not preclude success of the closed mitral commissurotomy. The early mortality rate was 1.5 per cent and the late mortality rate was 3.7 per cent. Reoperation was performed in only 1 patient 5 years
after commissurotomy for calcified mitral valve disease. Turina and his colleagues" stressed that the hemodynamic performance of the mitral valve before, during, and after commissurotomy can be judged only when the procedure is done in the closed, beating heart. They also indicated that the temptation to replace a grossly diseased but functionally competent valve is much greater in the open procedure. These authors feel that standard closed commissurotomy still has its place, not because of better anatomic or functional results but because many mitral valves can be preserved for several more years. A number of additional reports have presented very optimistic late follow-up data on the use of the standard closed commissurotomy procedure. Olinger and associates" reviewed the long-term (1.5 to 14 years; average of 5.5 years) follow-up of 23 patients selected for presentation because they all had moderate-to-severe mitral valve calcification and were submitted to closed commissurotomy. In this group of patients with severe mitral pathology, there was an increase in regurgitation in only 1 patient. There were no operative deaths and six late deaths; 4 patients developed restenosis. Olinger's group" concluded that the late results of closed commissurotomy, even in significantly calcified valves, are quite encouraging and that if these badly diseased valves can be made to function by commissurotomy, the immediate and long-term results are superior to those achieved by a prosthetic valve. Another excellent long-term follow-up on closed commissurotomy was recently presented by Nathaniels and associates" from the Massachusetts General Hospital. These authors reported on a series of 100 consecutive patients who survived closed mitral valvuloplasty between June, 1952, and January, 1955. They were then studied 15 years later. Accurate information was obtained on 88 of the 100 patients. Of 88 patients, 47 per cent were alive and 27 per cent had undergone no further procedure to the mitral valve. Fifteen per cent could
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be classified as in clinically satisfactory condition more than 15 years after surgery. These recent reports in the literature tend to corroborate the value of closed commissurotomy even in patients with moderately calcified valves. The long-term results of closed mitral commissurotomy in the reports by Turina,' Olinger, 5 Nathaniels," and others are certainly very encouraging. We feel that the standard closed commissurotomy does offer some specific advantages (continuous monitoring for mitral insufficiency and the possible engineering advantage of using a tethered valve), and these can be combined with the advantages of the standard open commissurotomy (safety of the pump oxygenator, the anterior approach, and easy conversion to prosthetic replacement) in the newer cannulated-closed commissurotomy. In addition, this operation seems to provide a very simple and satisfactory method for achieving a commissurotomy in a patient undergoing coronary artery bypass or aortic valve replacement, as well as the patient who has had a previous commissurotomy.
nary artery bypass or aortic valve replacement. In addition, it seems to be a valuable procedure for those patients who have undergone previous closed commissurotomy. 3. This procedure has been used routinely at this institution for the past 15 months in all patients with a moderately mobile, stenotic mitral valve. Twenty-seven patients (12 with calcium) have undergone an attempted commissurotomy with this technique. One patient with a badly diseased valve required a mitral prosthesis, and 1 patient with 1+ mitral insufficiency at the completion of the closed commissurotomy required mitral and tricuspid valve replacement 1 year later. All of the remaining 25 patients obtained satisfactory commissurotomies. 4. The cannulated-closed commissurotomy not only seems to incorporate the safety and all of the advantages of the standard open commissurotomy but also appears to reduce significantly the incidence of prosthetic valve replacement when compared to the open procedure.
Conclusions 1. It is felt that closed mitral commissurotomy through a sternal-split incision on pump stand-by, with the ascending aorta and both cavae cannulated, is an improved alternative to routine open mitral commissurotomy. This operation appears to combine the best features of the standard closed commissurotomy (the ability to monitor the mitral valve continuously for insufficiency and the possible engineering advantage of performing the commissurotomy on a tethered valve) with the advantages of open commissurotomy (safety of the pump oxygenator, anterior approach, and easy conversion to prosthetic replacement). 2. This operation offers a very simple and satisfactory method for performing a commissurotomy in combination with coro-
2 3 4
5
6
REFERENCES Messmer, S. G., Hallman, R., and Cooley, D. A.: Open Mitral Commissurotomy: Results of 100 Consecutive Cases, J. THORAC. CARDIOVASC. SURG. 62: 366, 1971. Robinson, G., and Atti, L.: Elective Open-Heart Surgery for Mitral Stenosis, Ann. Thorac. Surg. 6: 246, 1968. Roe, B. B., Edmunds, L. H., Jr., Fishman, N. H., and Hutchinson, J. C.: Open Mitral Valvulotomy, Ann. Thorac. Surg. 12: 483, 1971. Turina, M., Messmer, B. J., and Senning, A.: Closed Mitral Commissurotomy: Operative Resuits in Late Follow-Up in 137 Patients, Surgery 72: 812, 1972. Olinger, G. N., Rio, F. W., and Maloney, J. D.: Closed Valvulotomy for Calcific Mitral Stenosis, 1. THoRAc. CARDIOVASC. SURG. 62: 357, 1971. Nathaniels, E. K., Moncure, A. C., and Scannell, J. G.: A 15-Year Follow-Up of Closed Mitral Valvuloplasty, Ann. Thorac. Surg. 10: 27, 1970. (For Discussion, see page 80)