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Mitral Valve Replacement: Clinical Experience with the Ball-Valve Prosthesis
PROGRESS IN CARDIOVASCULAR SURGERY
Mitral Valve Replacement: Clinical Experience with the Ball-Valve Prosthesis* DONALD
O
B.
EFFLER, M.D. AND LAURENCE
Gleveland, Ohio
K.
GROVES, M.D.
important observation was that mitral valve insufficiency is a physiologic disturbance which may be produced by a wide variety of anatomic derangements. Evaluation of this early experience prompted us to conclude that our surgical efforts were palliative only. Furthermore, it seemed that future definitive treatment would depend upon prosthetic valve replacement. Perhaps these were the only worthwhile observations in our first report. Since 1958, most of our energy and interest have been directed toward the surgical treatment of acquired heart disease. We learned too that mitral stenosis can be a formidable disease not always relieved by commissurotomy even when performed under direct vision. It is our experience that the surgical treatment of the incompetent mitral valve, as well as certain types of mitral valve stenosis, requires an entirely new approach. Stimulated by the work of Starr and Edwards' in 1961, we undertook valve replacement with the ball-valve prosthesis. This report deals with the initial results and our current attitudes toward the surgical treatment of mitral valve insufficiency and selected forms of mitral valve stenosis.
PERATIONS FOR THE CORRECTION OF
insufficiency were advocated before the advent of open-heart surgery. Prime requisites for these surgical ventures were the surgeon's imagination, boldness, and technical facility. All of those operations are now obsolete. Some of them depended upon a form of baffle designed to reduce left ventricular regurgitation during the systolic phase; 1.2 others attempted to restore mitral valve competency by constriction of of the annulus: These operations, with their high mortality rates, represented the developmental phase in surgical treatment of acquired heart disease. With the advent of open-heart surgery, renewed efforts were directed toward correction of mitral valve insufficiency. Experience with extracorporeal circulation in the field of congenital heart disease offered a firm basis for the surgical attack upon acquired heart disease. When the mitral valve became accessible under direct vision it seemed likely that surgical cure of mitral insufficiency was at hand. In 1958, we reported upon our earlier experiences with open operations for mitral valve insufficiency." Our clinical experience was limited to 14 operations in which some form of annuloplasty or valvuloplasty had been utilized to restore mitral valve competency. Success was limited, and our initial enthusiasm was tempered by the harsh reality that mitral valve insufficiency is a disease of multiple facets. It became painfully evident that direct visualization of the mitral valve whether in the quiescent or in the beating heart was not in itself a guarantee of curative surgery. Perhaps our most
CLINICAL EXPERIENCE
The Starr-Edwards valve is the only prosthetic mitral valve that has been used at the Cleveland Clinic Hospital." To date,* 27 patients have undergone mitral valve replacement, 21 of whom are living. Deaths of the six patients were caused by: intractable failure, 24 and 72 hours after operation, two patients; the valve became dislocated six weeks postoperatively, one patient; and infections that led to fatal septicemia, three patients (Fig. 1).
*From the Department of Thoracic Surgery, The Cleveland Clinic Foundation.
*See addendum, page 538.
529
53°
EFFLER AND GROVES
Diseases of the Chest
I: Photo reproduction of the Starr-Edwards prosthetic mitral valve manufactured by Edwards Laboratories, Inc., Santa Ana, California. Recent modifications have been made to decrease the bulk o£ this prosthesis and reduce its total weight. The valve illustrated was used in this series; it is now supplanted by an improved model.
FIGURE
Although the time factor does not permit long-range evaluation (the first operation was performed on September 29, 1961), the progress of those who have survived is encouraging. All demonstrate improvement in cardiac status; in many there is dramatic reduction in heart size. Physiologic studies have been performed on some of the early postoperative patients, and offer objective proof that mitral regurgitation has been corrected. PATHOLOGIC CHANGES
As stated before, the term mitral valve insufficiency is more specifically applicable to a physiologic than an anatomic diagnosis. Incompetency of the mitral valve may be produced by a variety of anatomic derangements, but the physiologic disturbance is constant except for its extent. It has long been recognized that the anatomic features of mitral valve insufficiency may be difficult to evaluate at postmortem study when the heart is inert and the tissues are flaccid or have undergone postmortem changes. Moreover, this difficulty carries over into the operating room, where, under the apparently ideal condition of direct vision, the basic cause of insufficiency is not always apparent. Operating room experience, however, has taught us that there is more to incompetency of the
mitral valve than leaflet disease alone, and that primary involvement of the chordae tendineae, the papillary muscles, and even the left ventricular myocardium itself may be causative. Incompetency of the mitral valve may result from one or more of these anatomic derangements: (1) congenital cleft; (2 ) dilatation of the annulus; (3) ruptured chordae tendineae; (4) cicatricial shortening of the chordae tendineae; (5) leaflet fenestration; (6) fibrocalcareous distortion of the leaflets; (7) loss of leaflet substance
2: Photo of postmortem specimen from patient who died of overwhelming insufficiency of mitral valve after surgical laceration of anterior leaflet. This patient might have been saved if extracorporeal circulation had been available and valve replacement undertaken. FIGURE
Volume 43. No.5 May 1963
53 1
MITRAL VALVE REPLACEMENT
destroyed valve, incrusted by stone and scar, may regain normal dynamics is surgical whimsy (Fig. 3). As the surgeon gains experience in the treatment of mitral insufficiency and certain types of severe mitral valve stenosis, he gains appreciation of the complexities of the disease. Furthermore, he should have the reassuring knowledge that total valve replacement by a suitable prosthesis is now possible. OPERATIVE TECHNIC
2 3: Photo of specimen of resected mitral valve, viewed from atrial side. Both leaflets have been replaced by fibrocalcareous elements. It is unlikely that any operation, short of replacement, could offer return to normal cardiopulmonary dynamics. FIGURE
resulting from bacterial valvulitis; and (8) surgical laceration after operations for stenosis (Fig. 2). In addition, there are forms of valvular derangement that are difficult to classify---even to describe. Combinations of the listed derangements may occur. We have seen instances in which there is a peculiar attenuation of the leaflets associated with shortening of the chordae tendineae, the combination resulting in severe valvular incompetency. As difficult as the diseased valves may be to describe, even when visualized within the open beating heart, it may be nen more difficult to explain the basic cause. It seems unlikely that rheumatic heart disease can always be indicated for the gamut of derangements that result in mitral valve regurgitation. Stenosis of the mitral valve, particularly after a prior operation, may be associated with extensive calcification. This calcification may involve the leaflets, the chordae tendineae, the annulus, and even the atrial wall. When such extensive calcification occurs, the integrity of the mitral valve may be beyond repair. Attempts to relieve the resultant obstruction and restore normal mobility, when the valve as such no longer exists, are ill founded. The concept that a
It is our practice to utilize extracorporeal circulation* with mild hypothermia (32 down to 30· C.) in all operations where the possibility of mitral valve replacement is anticipated. We continue to use the rightsided approach to the mitral valve, entering *Disc Type Oxygenator, Pemco, Cleveland, Ohio. ~~
i
~f
3 I
./
,, ,, 4: Schematic illustration of the surgical incision utilized for the right-sided approach to the mitral valve. The thoracotomy is performed through the right fourth interspace; the internal mammary artery is divided, but the sternum is not transected. Arterial cannulation is usually made through a small incision that exposes the left common femoral artery.
FIGURE
53 2
EFFLER AND GROVES
Diseases of the Chest
5: Sagittal section to illustrate the right-sided approach to themitral valve. The right lung is retracted posteriorly and the left atrium is entered through or below the interatrial groove. The apex of the left ventricle may be above the level of the mitral valve itself; therefore, appropriate measures must be taken to protect the patient from air or gass embolus. As stated in the text: it is our custom to perfuse the operative field with carbon dioxide gass and also to vent the aortic root by needle during and after the period of intracardiac surgery. FIGURE
the chest by a submammary incision via the fourth interspace (Fig. 4). We prefer this approach because it provides ease in cannulation, and because the aortic root and its valve are accessible should this structure require some form of surgical treatment (Fig. 5). The basic cannulations of the two venae cavae and the left atrium are performed in standard fashion. The arterial cannula is inserted into the left common femoral artery that has been ex-
posed by a small incision in the left groin. An additional catheter is sutured into the medial aspect of the incision and the opposite end is connected to a tank of carbon dioxide gas; perfusion of the operative field throughout the entire open procedure reduces the hazard of air embolus. We believe that the utilization of a localized carbon dioxide atmosphere is an important adjunct when the open approach to the mitral valve is eJ;l1ployed.
6: The basic intracardiac cannulations and the atrial incision are demonstrated. As the incision is carried toward the inferior vena cava, it should be directed posteriorly to avoid entry into the right atrial chamber.
FIGURE
Volu= May 196~
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7: Direct inspection of the mitral valve while the heart is beating permits evaluation of the diseased structure. Before this is done, the entire left atrium must be carefully inspected for detection and removal of any thrombus or similar extraneous material that may be present. Inspection of the mitral valve through this approach permits final evaluation by the surgeon, and the decision is then made as to the advisability of prosthetic valve replacement. FIGURE
With total body perfusion, the temperature is dropped to a level between 32 and 30° C. This temperature permits maximum safety with minimal volume flow of perfusion. At this temperature, there is little likelihood of significant ventricular arrhythmias. When total bypass is in effect, the left heart is decompressed satisfactorily unless there is significant incompetency of the aortic valve. Decompression of the left heart is readily assessed by monitoring the left atrial pressure (Fig. 6). Failure of the left heart to become decompressed may mean that intermittent occlusion of the aortic root will be required. Under these circumstances a lower body temperature may be helpful. The left atrium is entered by an incision through or parallel to the interarterial groove. Residual blood is removed by suction and is returned to the pump oxygenator reservoir. As the left atrial chamber is emptied, direct inspection of the interior permits a search for a mural or an appendiceal thrombus. It is our practice to re-
move any element of clot that may be demonstrated within the atrial chamber or its appendix. To inspect the mitral valve within the beating heart usually requires some retraction, and we utilize a simple malleable blade type of retractor for this purpose (Fig. 7). It is our practice to "vent the aorta" by inserting an ordinary needle into the highest portion of the ascending arch whenever the valve is exposed or is manipulated. The small stream of blood that escapes from this vent enters the surgical field. Whatever gas is trapped in the left ventricular chamber may escape through this vent and will reduce the hazard of embolization within the systemic circulation or the coronary arterial circulation. This simple expedient of needle decompression can be an invaluable adjunct. Direct inspection of the valve coupled with digital assessment helps the surgical team to decide whether stenosis or insufficiency is the major factor. If insufficiency is obvious and the preliminary studies demonstrate significant elevation in left atrial
534
EFFLER AND GROVES
FIGURE 8A: Excision of the diseased mitral valve and its related structures is undertaken under direct vision. It should be emphasized that failure to remove sufficient papillary muscle and chordae tendineae may have serious consequence. Interference of the ball excursion within the prosthetic valve by tissue fragments may have disastrous results. Excision of the mitral valve may be facilitated by release of the underlying supporting structures as is demonstrated in this illustration.
and pulmonary artery pressures, then prosthetic valve replacement is undertaken. The same course would follow if the valve is heavily calcified and is, in our judgment, damaged beyond repair. If the situation is borderline, we attempt to repair the valve to the best of our ability and then to reassess left atrial and pulmonary artery pressures after the patient has been withdrawn from extracorporeal circulation and all factors have returned to the preoperative baselines. Should our efforts at valvulotomy, decortication, and manipulation be rewarded by appreciable drop in left atrial pressures, we terminate the operation and observe the patient's progress for an indefinite time. If, however, there has been no demonstrable improvement on the basis of left atrial pressure, there is little likelihood that lasting improvement could be expected; therefore, extracorporeal circulation is resumed and the patient is immediately pre-
Diseases of the Chest
pared for prosthetic valve replacement. The diseased mitral valve must be removed before a Starr-Edwards prosthesis is inserted (Fig. 8A). The leaflets are excised in such a way that a residual cuff of tissue remains; the prosthesis is secured to this tissue remnant, which is the sole support of the newly placed artificial valve (Fig. 8B). Removal of the diseased valve requires complete excision of its related chordae tendineae and papillary muscles. Remnants of tissue left within the left ventricle may project into the valve cage and interfere with excursion of the enclosed plastic ball, a situation that may be disastrous. Total removal of the diseased mitral valve may be rather difficult when there is extensive calcareous involvement that encroaches upon the annulus or the wall of either the atrium or the ventricle (Fig. 9). Meticulous and complete mitral valve excision is equally as important as insertion of the prosthesis itself. Although the ventricle continues to beat after the diseased valve has been removed, the likelihood of expressing air or gas into the aorta is remote; extrusion of gas or fluid from the ventricle requires some element of mitral valve competency. The pre-
leI
8B: Resected mitral valve with attached chordae tendineae and papillary muscles. FICURE
Volum. 43. No. May 1963
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MITRAL VALVE REPLACEMENT
535
FIGURE 9: The anterior leaflet is excised leaving a small remnant or cuff of tissue adjacent to the annulus. Unless excessive calcification is present, there is little difficulty in leaving an adequate sewing cuff.
pared site is measured by a disk-shaped instrument that corresponds to the caliber of the four available mitral prostheses (Fig. 10). Almost invariably the largest valve (size 4M) can be used. The prosthesis is then held over the field by an assistant, while a series of interrupted sutures* is placed through the cuff of remaining mitral valve tissue and the corresponding positions on the sewing rim of the Starr-Edwards
valve. It is our practice to mark the four quadrants first, and then to place two additional sutures within each quadrant corresponding to the numerals on the clock. When the 12 basic sutures have been placed, the prosthesis is then seated in the permanent position that it will occupy for the duration of the patient's life. Once seated, the ball must be held open to prevent propulsion of gas from the beating *Mersilene 000 Ethicon.
10: After complete removal of the diseased valve, the orifice is measured for prosthetic valve size. Whenever possible the largest available valve should be utilized. It is our practice to place four quadrant sutures first and then to add eight more; the 12 interrupted sutures conforming to the numerals of a clock face. Dacron suture material (Mersilene 000) is used for securing the prosthetic valve. We preferred silk because of its increased strength, lack of fatigability and the belief that it is less susceptible to early postoperative infection. Throughout this portion of the procedure and until the valve is seated, there is little likelihood that the left ventricle can extrude room air or gas (carbon dioxide). Blood that is returned into the field by way of the pulmonary veins or by partial incompetence of the aortic valve is removed by special suction.
FIGURE
Diseases of the Chest
EFFLER AND GROVES
left ventricle into the aorta. This may be accomplished by inserting a rubber catheter through the valve into the ventricle, or by using a special (Bjork) valve holder.* The 12 basic sutures are individually tied in sequence, beginning at whatever- point of the imaginary clock suits the surgeon best. Ideally, the cuff remnant of the patient's own valve should be tied over the atrial aspect of the prosthetic sewing rim. The 12 basic sutures are reinforced by additional interrupted sutures placed on the "halfhour" positions, and in this way, the prosthesis is secured by a minimum of 24 individual sutures. It is of utmost importance that the prosthetic valve remain open (in its diastolic ·Edwards Laboratories, Inc., Santa Ana, California.
position) throughout the period of insertion; otherwise, trapped gas may be expelled by the beating left ventricle into the aorta (Fig. 11). The supporting valve holder or the implanted catheter is removed only when the heart has become refilled with blood and the atrial incision is virtually closed. The venting needle in the aorta should be kept functioning until this time. After the insertion of the prosthesis and closure of the atrial incision, it is good practice to maintain decompression of the left atrium with the left atrial cannula. Although the ventricles may continue to beat throughout the entire procedure, myocardial tone may not be satisfactory, and overdistention of the left heart might have a deleterious effect. Extracorporeal circulation is not withdrawn until the body temperature is brought back to normal, and both the left ventricle and its contained prosthesis are functioning well. From the right-sided approach, the prosthetic valve is readily palpated beneath the left atrial chamber, and excursion of the ball is readily detected. As the mean arterial pressure returns to or exceeds the preoperative level, there should be a significant drop in the left atrial pressure as measured on the manometer. POSTOPERATIVE CARE
11: The final replacement of the mitral valve is demonstrated here. All sutures have been tied and additional sutures utilized where it is necessary. A simple catheter inserted through the annulus of the prosthesis, holds the valve open. This is most important and should be done when the valve is initially seated and throughout the entire time that sutures are secured. If the ball is allowed to close the mitral valve, the beating left ventricle will extrude air or gas (carbon dioxide) into the proximal aorta. We do not remove the rubber catheter until the left side of the heart has refilled with blood and the atrial incision virtually is closed. It is good practice to insert a needle in the proximal aorta at its highest point to permit escape of air or gas (carbon dioxide) that may, in spite of all precautions, remain trapped in the left ventricular chamber. FIGURE
It is our practice to place these patients in a special hospital unit where constant nursing care is provided by specially trained personnel. The postoperative care of these patients is similar to that for any patient who has received open-heart surgery for acquired valvular disease. There are, however, two adjuncts of particular importance whenever a prosthetic valve is employed: ( 1) prophylaxis against infection, and (2) anticoagulant therapy. Infection during the early, or even the late postoperative period, with a foreign body in the circulation may be disastrous. To date, our patients who have sustained a postoperative infection as manifested by a positive blood culture have not survived. The likelihood that a prosthetic valve once contaminated can be sterilized by the most
Volume 43. No.5 May 1963
MITRAL VALVE REPLACEMENT
537
FIGURE 12: Roentgenograms demonstrating the preoperative and the postoperative appearance of the first patient operated upon at the Cleveland Clinic Hospital with prosthetic mitral valve replacement. From a cardiac standpoint this patient remains stable, one and one-half years after operation. (Reproduced with permission of the Cleveland Clinic Quarterly, vol. 29, no. 4, October, 1962.)
vigorous of antibiotic therapy is remote. Prophylaxis consists of restriction of all visitors and nonessential personnel in both the operating room and the constant-care unit; each patient is allowed only one visitor per day during the time spent in the intensive care unit. All involved medical personnel and the patients themselves are tested constantly by nasal and throat cultures. Additional precautions too numerous to detail here are employed in a
constant effort to minimize the risk of secondary infection. In addition to this program, antibiotic therapy is initiated in the operating room, as the patient is being withdrawn from extracorporeal circulation, and is continued for a minimal period of seven days. The drugs in therapeutic doses are injected intravenously. The question of routine anticoagulant therapy must be considered when prosthetic valves are utilized. Administration of anti-
FIGURE 13: Comparison films to demonstrate the reduction in heart size that may occur within six weeks after insertion of prosthetic mitral valve. (Reproduced with the permission of the Cleveland Clinic Quarterly, vol. 29, no. 4, October, 1962.)
EFFLER AND GROVES
coagulants early in the postoperative period is common procedure in many centers where work is done in this field. Our own attitude toward anticoagulant therapy has undergone considerable vacillation. At the present, anticoagulants are not used in the routine care of patients who have received Starr-Edwards prosthetic valves. Admittedly, several of our patients have demonstrated embolic episodes after insertion of these prosthetic devices. However, in our experience, the incidence of complications following anticoagulant therapy has outweighed the potential benefit. Apparently the combination of extracorporeal circulation and valve replacement potentiates a greater likelihood of serious bleeding manifestations. Time and the combined experience of other surgeons will be the final determinant of the role of anticoagulant therapy. COMMENT
Initial enthusiasm for the surgical treatment of mitral insufficiency by annuloplasty or some form of valvuloplasty has dimmed. Whereas some patients had objective evidence of initial success, the longterm results have been uniformly disappointing. It should be emphasized that this attitude is based entirely upon our own surgical efforts in the treatment of mitral insufficiency, and is not a castigation of the results reported by others. Our attitude based upon the above-described experience has prompted our interest in the prosthetic valve replacement utilizing the Starr-Edwards ball-valve. Our attitude toward treatment of calcific mitral stenosis of severe degree is somewhat similar. It seems quite unlikely that satisfactory therapy can be offered by any type of commissurotomy, even that combined with painstaking decortication, when the basic integrity of the valve and its supporting structures is beyond repair. Selection of those patients for whom prosthetic valve replacement is suitable is a matter of the surgeon's best judgment in the individual case. In the initial appraisal, careful preoperative studies will include
Diseases of the Chest
catheterization of the left heart and cinephotography. In the last analysis, however, it will be in the operating room itself that the final decision of specific therapy will be reached. The surgical team should be prepared whenever operating upon the patient with mitral valve insufficiency or calcific mitral stenosis to undertake valve replacement, if the need is evident. The patient who comes to operation in chronic cardiac failure has little chance for improvement or even of survival unless adequate mechanical relief is offered him. The initial success that has attended the use of the Starr-Edwards prosthetic mitral valve is most encouraging. At this writing it is our belief that prosthetic valve replacement is the preferred treatment for patients who suffer from significant mitral valve incompetency. Likewise, in selected patients with calcific mitral stenosis total valve replacement is performed. At the moment, the authors' enthusiasm is high, and indications for valve replacement are broadening. Whether or not this enthusiasm will be tempered by the factual data, can only be determined by long-term evaluation. ADDENDUM: Additional operations have been perfonned since this report was submitted to the Editor. By March 15, 1963, a total of 42 operations for Starr-Edwards mitral valve replacements have been perfonned; 34 patients are alive at this time.
2
3
4
5 6
REFERENCES BAILEY, C. P., JAMISON, W. L., BAKST, A. E., BOLTON, H. E., NICHOLS, H. T. AND GEMEINHARDT, W.: "Surgical Correction of Mitral Insufficiency by Use of Pericardial Grafts," j. Thor. Surg., 28: 551; discussion, 624, 1954. HARKEN, D. E., BLACK, H., ELLIS, L. B. AND DEXTER, L.: "Surgical Correction of Mitral Insufficiency," j. Thor. Surg., 28:604; discussion, 624, 1954. DAVILA, J. C., GLOVER, R. P., TROUT, R. G., MANSURE, F. S., WOOD, N. E., JANTON, O. H. AND lArA, B. D.: "Circumferential Suture of Mitral Ring; Method for Surgical Correction of Mitral Insufficiency," j. Thor. Surg., 30: 531; discussion, 560, 1955. EFFLER, D. B., GROVES, L. K., MARTINEZ, W. V. AND KOLFF, W. J.: "Open-Heart Surgery for Mitral Insufficiency," j. Thor. Surg., 36: 665; discussion, 690, 1958. STARR, A. AND EDWARDS, M. L.: "Mitral Replacement: Clinical Experience with Ball-Valve Prosthesis," Ann. Surg., 154:726, 1961. EFFLER, D. B.: "Defects of the Mitral Valve; Current Concepts of Surgical Treatment," Cleveland Clin. Quart., 29: 167, 1962.
Mitral Valve Replacement: Clinical Experience with the Ball-Valve Prosthesis* DONALD
O
B.
EFFLER, M.D. AND LAURENCE
Gleveland, Ohio
K.
GROVES, M.D.
important observation was that mitral valve insufficiency is a physiologic disturbance which may be produced by a wide variety of anatomic derangements. Evaluation of this early experience prompted us to conclude that our surgical efforts were palliative only. Furthermore, it seemed that future definitive treatment would depend upon prosthetic valve replacement. Perhaps these were the only worthwhile observations in our first report. Since 1958, most of our energy and interest have been directed toward the surgical treatment of acquired heart disease. We learned too that mitral stenosis can be a formidable disease not always relieved by commissurotomy even when performed under direct vision. It is our experience that the surgical treatment of the incompetent mitral valve, as well as certain types of mitral valve stenosis, requires an entirely new approach. Stimulated by the work of Starr and Edwards' in 1961, we undertook valve replacement with the ball-valve prosthesis. This report deals with the initial results and our current attitudes toward the surgical treatment of mitral valve insufficiency and selected forms of mitral valve stenosis.
PERATIONS FOR THE CORRECTION OF
insufficiency were advocated before the advent of open-heart surgery. Prime requisites for these surgical ventures were the surgeon's imagination, boldness, and technical facility. All of those operations are now obsolete. Some of them depended upon a form of baffle designed to reduce left ventricular regurgitation during the systolic phase; 1.2 others attempted to restore mitral valve competency by constriction of of the annulus: These operations, with their high mortality rates, represented the developmental phase in surgical treatment of acquired heart disease. With the advent of open-heart surgery, renewed efforts were directed toward correction of mitral valve insufficiency. Experience with extracorporeal circulation in the field of congenital heart disease offered a firm basis for the surgical attack upon acquired heart disease. When the mitral valve became accessible under direct vision it seemed likely that surgical cure of mitral insufficiency was at hand. In 1958, we reported upon our earlier experiences with open operations for mitral valve insufficiency." Our clinical experience was limited to 14 operations in which some form of annuloplasty or valvuloplasty had been utilized to restore mitral valve competency. Success was limited, and our initial enthusiasm was tempered by the harsh reality that mitral valve insufficiency is a disease of multiple facets. It became painfully evident that direct visualization of the mitral valve whether in the quiescent or in the beating heart was not in itself a guarantee of curative surgery. Perhaps our most
CLINICAL EXPERIENCE
The Starr-Edwards valve is the only prosthetic mitral valve that has been used at the Cleveland Clinic Hospital." To date,* 27 patients have undergone mitral valve replacement, 21 of whom are living. Deaths of the six patients were caused by: intractable failure, 24 and 72 hours after operation, two patients; the valve became dislocated six weeks postoperatively, one patient; and infections that led to fatal septicemia, three patients (Fig. 1).
*From the Department of Thoracic Surgery, The Cleveland Clinic Foundation.
*See addendum, page 538.
529
53°
EFFLER AND GROVES
Diseases of the Chest
I: Photo reproduction of the Starr-Edwards prosthetic mitral valve manufactured by Edwards Laboratories, Inc., Santa Ana, California. Recent modifications have been made to decrease the bulk o£ this prosthesis and reduce its total weight. The valve illustrated was used in this series; it is now supplanted by an improved model.
FIGURE
Although the time factor does not permit long-range evaluation (the first operation was performed on September 29, 1961), the progress of those who have survived is encouraging. All demonstrate improvement in cardiac status; in many there is dramatic reduction in heart size. Physiologic studies have been performed on some of the early postoperative patients, and offer objective proof that mitral regurgitation has been corrected. PATHOLOGIC CHANGES
As stated before, the term mitral valve insufficiency is more specifically applicable to a physiologic than an anatomic diagnosis. Incompetency of the mitral valve may be produced by a variety of anatomic derangements, but the physiologic disturbance is constant except for its extent. It has long been recognized that the anatomic features of mitral valve insufficiency may be difficult to evaluate at postmortem study when the heart is inert and the tissues are flaccid or have undergone postmortem changes. Moreover, this difficulty carries over into the operating room, where, under the apparently ideal condition of direct vision, the basic cause of insufficiency is not always apparent. Operating room experience, however, has taught us that there is more to incompetency of the
mitral valve than leaflet disease alone, and that primary involvement of the chordae tendineae, the papillary muscles, and even the left ventricular myocardium itself may be causative. Incompetency of the mitral valve may result from one or more of these anatomic derangements: (1) congenital cleft; (2 ) dilatation of the annulus; (3) ruptured chordae tendineae; (4) cicatricial shortening of the chordae tendineae; (5) leaflet fenestration; (6) fibrocalcareous distortion of the leaflets; (7) loss of leaflet substance
2: Photo of postmortem specimen from patient who died of overwhelming insufficiency of mitral valve after surgical laceration of anterior leaflet. This patient might have been saved if extracorporeal circulation had been available and valve replacement undertaken. FIGURE
Volume 43. No.5 May 1963
53 1
MITRAL VALVE REPLACEMENT
destroyed valve, incrusted by stone and scar, may regain normal dynamics is surgical whimsy (Fig. 3). As the surgeon gains experience in the treatment of mitral insufficiency and certain types of severe mitral valve stenosis, he gains appreciation of the complexities of the disease. Furthermore, he should have the reassuring knowledge that total valve replacement by a suitable prosthesis is now possible. OPERATIVE TECHNIC
2 3: Photo of specimen of resected mitral valve, viewed from atrial side. Both leaflets have been replaced by fibrocalcareous elements. It is unlikely that any operation, short of replacement, could offer return to normal cardiopulmonary dynamics. FIGURE
resulting from bacterial valvulitis; and (8) surgical laceration after operations for stenosis (Fig. 2). In addition, there are forms of valvular derangement that are difficult to classify---even to describe. Combinations of the listed derangements may occur. We have seen instances in which there is a peculiar attenuation of the leaflets associated with shortening of the chordae tendineae, the combination resulting in severe valvular incompetency. As difficult as the diseased valves may be to describe, even when visualized within the open beating heart, it may be nen more difficult to explain the basic cause. It seems unlikely that rheumatic heart disease can always be indicated for the gamut of derangements that result in mitral valve regurgitation. Stenosis of the mitral valve, particularly after a prior operation, may be associated with extensive calcification. This calcification may involve the leaflets, the chordae tendineae, the annulus, and even the atrial wall. When such extensive calcification occurs, the integrity of the mitral valve may be beyond repair. Attempts to relieve the resultant obstruction and restore normal mobility, when the valve as such no longer exists, are ill founded. The concept that a
It is our practice to utilize extracorporeal circulation* with mild hypothermia (32 down to 30· C.) in all operations where the possibility of mitral valve replacement is anticipated. We continue to use the rightsided approach to the mitral valve, entering *Disc Type Oxygenator, Pemco, Cleveland, Ohio. ~~
i
~f
3 I
./
,, ,, 4: Schematic illustration of the surgical incision utilized for the right-sided approach to the mitral valve. The thoracotomy is performed through the right fourth interspace; the internal mammary artery is divided, but the sternum is not transected. Arterial cannulation is usually made through a small incision that exposes the left common femoral artery.
FIGURE
53 2
EFFLER AND GROVES
Diseases of the Chest
5: Sagittal section to illustrate the right-sided approach to themitral valve. The right lung is retracted posteriorly and the left atrium is entered through or below the interatrial groove. The apex of the left ventricle may be above the level of the mitral valve itself; therefore, appropriate measures must be taken to protect the patient from air or gass embolus. As stated in the text: it is our custom to perfuse the operative field with carbon dioxide gass and also to vent the aortic root by needle during and after the period of intracardiac surgery. FIGURE
the chest by a submammary incision via the fourth interspace (Fig. 4). We prefer this approach because it provides ease in cannulation, and because the aortic root and its valve are accessible should this structure require some form of surgical treatment (Fig. 5). The basic cannulations of the two venae cavae and the left atrium are performed in standard fashion. The arterial cannula is inserted into the left common femoral artery that has been ex-
posed by a small incision in the left groin. An additional catheter is sutured into the medial aspect of the incision and the opposite end is connected to a tank of carbon dioxide gas; perfusion of the operative field throughout the entire open procedure reduces the hazard of air embolus. We believe that the utilization of a localized carbon dioxide atmosphere is an important adjunct when the open approach to the mitral valve is eJ;l1ployed.
6: The basic intracardiac cannulations and the atrial incision are demonstrated. As the incision is carried toward the inferior vena cava, it should be directed posteriorly to avoid entry into the right atrial chamber.
FIGURE
Volu= May 196~
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No. )
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7: Direct inspection of the mitral valve while the heart is beating permits evaluation of the diseased structure. Before this is done, the entire left atrium must be carefully inspected for detection and removal of any thrombus or similar extraneous material that may be present. Inspection of the mitral valve through this approach permits final evaluation by the surgeon, and the decision is then made as to the advisability of prosthetic valve replacement. FIGURE
With total body perfusion, the temperature is dropped to a level between 32 and 30° C. This temperature permits maximum safety with minimal volume flow of perfusion. At this temperature, there is little likelihood of significant ventricular arrhythmias. When total bypass is in effect, the left heart is decompressed satisfactorily unless there is significant incompetency of the aortic valve. Decompression of the left heart is readily assessed by monitoring the left atrial pressure (Fig. 6). Failure of the left heart to become decompressed may mean that intermittent occlusion of the aortic root will be required. Under these circumstances a lower body temperature may be helpful. The left atrium is entered by an incision through or parallel to the interarterial groove. Residual blood is removed by suction and is returned to the pump oxygenator reservoir. As the left atrial chamber is emptied, direct inspection of the interior permits a search for a mural or an appendiceal thrombus. It is our practice to re-
move any element of clot that may be demonstrated within the atrial chamber or its appendix. To inspect the mitral valve within the beating heart usually requires some retraction, and we utilize a simple malleable blade type of retractor for this purpose (Fig. 7). It is our practice to "vent the aorta" by inserting an ordinary needle into the highest portion of the ascending arch whenever the valve is exposed or is manipulated. The small stream of blood that escapes from this vent enters the surgical field. Whatever gas is trapped in the left ventricular chamber may escape through this vent and will reduce the hazard of embolization within the systemic circulation or the coronary arterial circulation. This simple expedient of needle decompression can be an invaluable adjunct. Direct inspection of the valve coupled with digital assessment helps the surgical team to decide whether stenosis or insufficiency is the major factor. If insufficiency is obvious and the preliminary studies demonstrate significant elevation in left atrial
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FIGURE 8A: Excision of the diseased mitral valve and its related structures is undertaken under direct vision. It should be emphasized that failure to remove sufficient papillary muscle and chordae tendineae may have serious consequence. Interference of the ball excursion within the prosthetic valve by tissue fragments may have disastrous results. Excision of the mitral valve may be facilitated by release of the underlying supporting structures as is demonstrated in this illustration.
and pulmonary artery pressures, then prosthetic valve replacement is undertaken. The same course would follow if the valve is heavily calcified and is, in our judgment, damaged beyond repair. If the situation is borderline, we attempt to repair the valve to the best of our ability and then to reassess left atrial and pulmonary artery pressures after the patient has been withdrawn from extracorporeal circulation and all factors have returned to the preoperative baselines. Should our efforts at valvulotomy, decortication, and manipulation be rewarded by appreciable drop in left atrial pressures, we terminate the operation and observe the patient's progress for an indefinite time. If, however, there has been no demonstrable improvement on the basis of left atrial pressure, there is little likelihood that lasting improvement could be expected; therefore, extracorporeal circulation is resumed and the patient is immediately pre-
Diseases of the Chest
pared for prosthetic valve replacement. The diseased mitral valve must be removed before a Starr-Edwards prosthesis is inserted (Fig. 8A). The leaflets are excised in such a way that a residual cuff of tissue remains; the prosthesis is secured to this tissue remnant, which is the sole support of the newly placed artificial valve (Fig. 8B). Removal of the diseased valve requires complete excision of its related chordae tendineae and papillary muscles. Remnants of tissue left within the left ventricle may project into the valve cage and interfere with excursion of the enclosed plastic ball, a situation that may be disastrous. Total removal of the diseased mitral valve may be rather difficult when there is extensive calcareous involvement that encroaches upon the annulus or the wall of either the atrium or the ventricle (Fig. 9). Meticulous and complete mitral valve excision is equally as important as insertion of the prosthesis itself. Although the ventricle continues to beat after the diseased valve has been removed, the likelihood of expressing air or gas into the aorta is remote; extrusion of gas or fluid from the ventricle requires some element of mitral valve competency. The pre-
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8B: Resected mitral valve with attached chordae tendineae and papillary muscles. FICURE
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FIGURE 9: The anterior leaflet is excised leaving a small remnant or cuff of tissue adjacent to the annulus. Unless excessive calcification is present, there is little difficulty in leaving an adequate sewing cuff.
pared site is measured by a disk-shaped instrument that corresponds to the caliber of the four available mitral prostheses (Fig. 10). Almost invariably the largest valve (size 4M) can be used. The prosthesis is then held over the field by an assistant, while a series of interrupted sutures* is placed through the cuff of remaining mitral valve tissue and the corresponding positions on the sewing rim of the Starr-Edwards
valve. It is our practice to mark the four quadrants first, and then to place two additional sutures within each quadrant corresponding to the numerals on the clock. When the 12 basic sutures have been placed, the prosthesis is then seated in the permanent position that it will occupy for the duration of the patient's life. Once seated, the ball must be held open to prevent propulsion of gas from the beating *Mersilene 000 Ethicon.
10: After complete removal of the diseased valve, the orifice is measured for prosthetic valve size. Whenever possible the largest available valve should be utilized. It is our practice to place four quadrant sutures first and then to add eight more; the 12 interrupted sutures conforming to the numerals of a clock face. Dacron suture material (Mersilene 000) is used for securing the prosthetic valve. We preferred silk because of its increased strength, lack of fatigability and the belief that it is less susceptible to early postoperative infection. Throughout this portion of the procedure and until the valve is seated, there is little likelihood that the left ventricle can extrude room air or gas (carbon dioxide). Blood that is returned into the field by way of the pulmonary veins or by partial incompetence of the aortic valve is removed by special suction.
FIGURE
Diseases of the Chest
EFFLER AND GROVES
left ventricle into the aorta. This may be accomplished by inserting a rubber catheter through the valve into the ventricle, or by using a special (Bjork) valve holder.* The 12 basic sutures are individually tied in sequence, beginning at whatever- point of the imaginary clock suits the surgeon best. Ideally, the cuff remnant of the patient's own valve should be tied over the atrial aspect of the prosthetic sewing rim. The 12 basic sutures are reinforced by additional interrupted sutures placed on the "halfhour" positions, and in this way, the prosthesis is secured by a minimum of 24 individual sutures. It is of utmost importance that the prosthetic valve remain open (in its diastolic ·Edwards Laboratories, Inc., Santa Ana, California.
position) throughout the period of insertion; otherwise, trapped gas may be expelled by the beating left ventricle into the aorta (Fig. 11). The supporting valve holder or the implanted catheter is removed only when the heart has become refilled with blood and the atrial incision is virtually closed. The venting needle in the aorta should be kept functioning until this time. After the insertion of the prosthesis and closure of the atrial incision, it is good practice to maintain decompression of the left atrium with the left atrial cannula. Although the ventricles may continue to beat throughout the entire procedure, myocardial tone may not be satisfactory, and overdistention of the left heart might have a deleterious effect. Extracorporeal circulation is not withdrawn until the body temperature is brought back to normal, and both the left ventricle and its contained prosthesis are functioning well. From the right-sided approach, the prosthetic valve is readily palpated beneath the left atrial chamber, and excursion of the ball is readily detected. As the mean arterial pressure returns to or exceeds the preoperative level, there should be a significant drop in the left atrial pressure as measured on the manometer. POSTOPERATIVE CARE
11: The final replacement of the mitral valve is demonstrated here. All sutures have been tied and additional sutures utilized where it is necessary. A simple catheter inserted through the annulus of the prosthesis, holds the valve open. This is most important and should be done when the valve is initially seated and throughout the entire time that sutures are secured. If the ball is allowed to close the mitral valve, the beating left ventricle will extrude air or gas (carbon dioxide) into the proximal aorta. We do not remove the rubber catheter until the left side of the heart has refilled with blood and the atrial incision virtually is closed. It is good practice to insert a needle in the proximal aorta at its highest point to permit escape of air or gas (carbon dioxide) that may, in spite of all precautions, remain trapped in the left ventricular chamber. FIGURE
It is our practice to place these patients in a special hospital unit where constant nursing care is provided by specially trained personnel. The postoperative care of these patients is similar to that for any patient who has received open-heart surgery for acquired valvular disease. There are, however, two adjuncts of particular importance whenever a prosthetic valve is employed: ( 1) prophylaxis against infection, and (2) anticoagulant therapy. Infection during the early, or even the late postoperative period, with a foreign body in the circulation may be disastrous. To date, our patients who have sustained a postoperative infection as manifested by a positive blood culture have not survived. The likelihood that a prosthetic valve once contaminated can be sterilized by the most
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FIGURE 12: Roentgenograms demonstrating the preoperative and the postoperative appearance of the first patient operated upon at the Cleveland Clinic Hospital with prosthetic mitral valve replacement. From a cardiac standpoint this patient remains stable, one and one-half years after operation. (Reproduced with permission of the Cleveland Clinic Quarterly, vol. 29, no. 4, October, 1962.)
vigorous of antibiotic therapy is remote. Prophylaxis consists of restriction of all visitors and nonessential personnel in both the operating room and the constant-care unit; each patient is allowed only one visitor per day during the time spent in the intensive care unit. All involved medical personnel and the patients themselves are tested constantly by nasal and throat cultures. Additional precautions too numerous to detail here are employed in a
constant effort to minimize the risk of secondary infection. In addition to this program, antibiotic therapy is initiated in the operating room, as the patient is being withdrawn from extracorporeal circulation, and is continued for a minimal period of seven days. The drugs in therapeutic doses are injected intravenously. The question of routine anticoagulant therapy must be considered when prosthetic valves are utilized. Administration of anti-
FIGURE 13: Comparison films to demonstrate the reduction in heart size that may occur within six weeks after insertion of prosthetic mitral valve. (Reproduced with the permission of the Cleveland Clinic Quarterly, vol. 29, no. 4, October, 1962.)
EFFLER AND GROVES
coagulants early in the postoperative period is common procedure in many centers where work is done in this field. Our own attitude toward anticoagulant therapy has undergone considerable vacillation. At the present, anticoagulants are not used in the routine care of patients who have received Starr-Edwards prosthetic valves. Admittedly, several of our patients have demonstrated embolic episodes after insertion of these prosthetic devices. However, in our experience, the incidence of complications following anticoagulant therapy has outweighed the potential benefit. Apparently the combination of extracorporeal circulation and valve replacement potentiates a greater likelihood of serious bleeding manifestations. Time and the combined experience of other surgeons will be the final determinant of the role of anticoagulant therapy. COMMENT
Initial enthusiasm for the surgical treatment of mitral insufficiency by annuloplasty or some form of valvuloplasty has dimmed. Whereas some patients had objective evidence of initial success, the longterm results have been uniformly disappointing. It should be emphasized that this attitude is based entirely upon our own surgical efforts in the treatment of mitral insufficiency, and is not a castigation of the results reported by others. Our attitude based upon the above-described experience has prompted our interest in the prosthetic valve replacement utilizing the Starr-Edwards ball-valve. Our attitude toward treatment of calcific mitral stenosis of severe degree is somewhat similar. It seems quite unlikely that satisfactory therapy can be offered by any type of commissurotomy, even that combined with painstaking decortication, when the basic integrity of the valve and its supporting structures is beyond repair. Selection of those patients for whom prosthetic valve replacement is suitable is a matter of the surgeon's best judgment in the individual case. In the initial appraisal, careful preoperative studies will include
Diseases of the Chest
catheterization of the left heart and cinephotography. In the last analysis, however, it will be in the operating room itself that the final decision of specific therapy will be reached. The surgical team should be prepared whenever operating upon the patient with mitral valve insufficiency or calcific mitral stenosis to undertake valve replacement, if the need is evident. The patient who comes to operation in chronic cardiac failure has little chance for improvement or even of survival unless adequate mechanical relief is offered him. The initial success that has attended the use of the Starr-Edwards prosthetic mitral valve is most encouraging. At this writing it is our belief that prosthetic valve replacement is the preferred treatment for patients who suffer from significant mitral valve incompetency. Likewise, in selected patients with calcific mitral stenosis total valve replacement is performed. At the moment, the authors' enthusiasm is high, and indications for valve replacement are broadening. Whether or not this enthusiasm will be tempered by the factual data, can only be determined by long-term evaluation. ADDENDUM: Additional operations have been perfonned since this report was submitted to the Editor. By March 15, 1963, a total of 42 operations for Starr-Edwards mitral valve replacements have been perfonned; 34 patients are alive at this time.
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REFERENCES BAILEY, C. P., JAMISON, W. L., BAKST, A. E., BOLTON, H. E., NICHOLS, H. T. AND GEMEINHARDT, W.: "Surgical Correction of Mitral Insufficiency by Use of Pericardial Grafts," j. Thor. Surg., 28: 551; discussion, 624, 1954. HARKEN, D. E., BLACK, H., ELLIS, L. B. AND DEXTER, L.: "Surgical Correction of Mitral Insufficiency," j. Thor. Surg., 28:604; discussion, 624, 1954. DAVILA, J. C., GLOVER, R. P., TROUT, R. G., MANSURE, F. S., WOOD, N. E., JANTON, O. H. AND lArA, B. D.: "Circumferential Suture of Mitral Ring; Method for Surgical Correction of Mitral Insufficiency," j. Thor. Surg., 30: 531; discussion, 560, 1955. EFFLER, D. B., GROVES, L. K., MARTINEZ, W. V. AND KOLFF, W. J.: "Open-Heart Surgery for Mitral Insufficiency," j. Thor. Surg., 36: 665; discussion, 690, 1958. STARR, A. AND EDWARDS, M. L.: "Mitral Replacement: Clinical Experience with Ball-Valve Prosthesis," Ann. Surg., 154:726, 1961. EFFLER, D. B.: "Defects of the Mitral Valve; Current Concepts of Surgical Treatment," Cleveland Clin. Quart., 29: 167, 1962.