Introduction

Although it's incidence is decreasing in western countries,rheumatic mitral disease is still frequent in developing countries. Successful mitral valve repair can be accomplished regardless of the etiology of dysfunction. The decision to perform valve repair depends more on the extent of the etiology. Nevertheless,the severe pathologic changes that often accompany advanced rheumatic valve disease are less likely to be amenable to repair than are changes that arise from other processes (₁). Because avoidance of atrial fibrillation (AF) and its associated risks is a major goal of mitral valve repair, recent onset of AF has been established as another indication fort he early operative correction of mitral insufficiency. Mitral valve repair in rheumatic disease is technically more difficult,and there is little information on the long-term stability of this technique (₂). The aim of mitral valve repair is to obtain a component mitral valve with the largest possible orifice and this repair represents a beter alternative than valve replacement,as previously described, in terms of a higher survival rate and a significant reduction in mitral valve-related complications (₂,₃). In this study we're presenting a new valve reconstruction technique used successfully in a case who had severe mitral insufficiency with giant left atrium due to rheumatic disease.

Case Presentation

Our case was 63 years old woman and was followed for rheumatic mitral insufficiency (MR) diagnosis for 5 years. She was admitted to our Cardiology Outpatient Clinic for dyspnea and increasing fatigue. She presented with cardiac decompensation refractory to medical treatment. She presented with pulmonary edema 3 months ago before admittance. She was in New York Heart Association (NYHA) functional class IV at presentation. She had a AF rhythm in electrocardiography.Chest X-ray showed cardiomegaly (CTI:0.75), hilar congestion and flattening of pulmonary conus.Transthoracic echocardiography (TTE) showed severe MR. Diameter of left atrium 83x99 mm (apical 4 chambers) and left ventricle(58/35mm)were widened. Left ventricle EF was 60%.Pulmonary arterial pressure was 45/21 mmHg. Other valves' functions included minimal aortic and tricuspid regurgitation. Her cardiac coronary arteriography (CAG) and cardiac catheterization were performed. It was confirmed that EF:60%. Coronary arteries were normal.Catheterization showed 4.° MR and 1.° AR (Figure 1). She went under operation.

Figure 1

Figure 1: Her left ventricular catheterization showed severe mitral regurgitation and giant left atrium.

Surgical Technique

She was operated under endotracheal general anesthesia and in supine position.Following a median sternotomy,pericard was opened longitudinally. After heparinization, extra-corporeal circulation is established between the venae cavae and the ascending aorta. A cross clamp was placed on aorta and by antegrad intermittant isothermic blood cardioplegy from aortic root,cardiac arrest was established.Hypothermia was moderate (28°c). A vent was placed via the right superior pulmonary vein. Standard left atriotomy was made from interatrial junction. Our standard radiofrequency ablation technique was performed with Cardioblate BP (bipolar) Surgical Ablation Device (Medtronic 60821) (Figure 2).

Figure 2

Figure 2: Left pulmonary veins approach during RF ablation.

Cross clamp duration lengthened 5 minutes with this accompanying procedure. Left auriculopexi was performed with primary sutures of 3/0 monofilament polypropylene from left atrium. The entire valvular apparatus was carefully examined in order to assess the feasibility of reconstructive surgery and to plan the operative technique. The valvular apparatus was then mobilized as an entire unit with a nerve hook in order to assess tissue flexibility and to identify leaflet restriction. The annulus was severely dilatated. Although some fibrocalcific areas near the free edge of anterior leaflet were seen there wasn't any tissue loss. It could cover whole mitral orifice there wasn't commisural fusion (Figure 3).

Figure 3

Figure 3: View of mitral valve's elements peroperatively.

Posterior leaflet showed some fibrotic areas and minimal tissue loss.Chordas were shortened and thickened, papillary muscles were hypertrophic and very close to annulus at subvalvular apparey. The papillary muscle was giving chordas to the both leaflets at the posteromedial commissure.

The bilateral comissures were incised while leaving intact one milimeter of valvular tissue as in the normal anatomy.The underlying chordaes and papillary muscles were then incised accordingly (Figure 4).

Figure 4

Figure 4: Imagination of the bilateral comissurotomies and anterolateral chordae+papillary muscle division.

After this step we performed bilateral segmental annuloplasty. This procedure may also be used to achieve better approximation of leaflet tissue with the placement of mattress stitches at the commissures. We tested the valve competence after this step on observing valve closure while the left ventricular cavity is filled with saline solution. There wasn't saline regurgitation.

From a surgical point of view,a flexible ring reduces the tension of the sutures,decreasing the likelihood of ring dehiscence. The ring can also be split. This is particularly useful in those cases in which the surgeon doubts the quality of the repair. For these reasons we performed mitral ring annuloplasty with Medtronic-H608H33 Duran flexibl ring model H608H,33 mm. We re-tested the valve competence after this step on observing valve closure with saline solution. Valve competence and closure were excellent. Left atriotomy closed standartly. Postoperative rhythm was sinusal. She was no required inotropic support during weaning from cardiopulmonary bypass and early postoperative period. The volume of blood transfused was 2 units. The quantity of mediastinal drainage was 400 cc. She was extubated after an intubation duration 9 hours and stayed in the intensive care for 2 days. The hospital stay was 9 days. Postoperatively at the discharge day and after 3 months an echocardiographic investigation was revealed no regurgitation for the repaired mitral valve (Figure 5).

Figure 5

Figure 5: During the third postoperative month,control echocardiography showed any regurgitation on repaired nativ valve

Postoperatively, the mitral valve area was found to be 2.47 cm ² by pressure half-time echocardiography (Figure 6).

Figure 6

Figure 6: Postoperatively,the mitral valve area was found to be 2.47cm

The left atrium diameter was found to be 83x99 mm preoperatively,50x75x52 mm postoperatively. The mean gradient of the mitral valve was 4.17 mmHg. The functional capacity of our patient improved dramatically and she was in NYHA functional class I-II. We found no postoperative cardiac decompensation symptom in our patient during late follow-up and she was followed at our outpatient clinic without additional problem.

Discussion

There have been few clinical series reported analyzing a homogeneous patient population with the same valve etiology, and it has been pointed out that the repair in rheumatic valve disease is technically more difficult and less stable than in degenerative lesion (₄). Mitral insufficiency is a frequent valvular pathology and may require surgical intervention when the lesion is severe enough to cause heart failure in spite of medical therapy. Chronic mitral insufficiency produces cardiac enlargement, volume overload of the left ventricle,and eventual mtocardial detoriation (₁). The most important factor in evaluating mitral regurgitation is the degree of left ventricular enlargement. Progressive cardiac enlargement is an indication for operation. Surgical patients with preoperative NYHA class III or IV status had a significantly reduced 5 year survival rate,and 50% of the late deaths were attributable to heart failure(₅).

Since 1970s,reconstructive surgery of the mitral valve was implanted definitively after the pioneering work of Carpentier (₆). Since then,clinical experience has shown that this conservative surgery involves minor hospital mortality and more satisfactory long-term clinical results(₄,₇).Surgical techniques are evolving continously and making it possible to treat lesions that we previously thought were beyond repair.

Since their introduction,annuloplasty rings have become essential components of reconstructive surgery of mitral and tricuspid valves. Their safety and durability have been proven in numerous clinical studies. The ring obviously deals only with the problems of valve area and does not address the other lesions that must be treated. When redundant leaflet tissue appears to be located in a segment of the mitral valve, the mitral valve annulus may be narrowed by placing interrupted pledget-reinforced mattress stitches through the annulus at the comissure and drawing the redundant valve tissue into the mattress stitch at the annulus. This repair is the least controllable and least symmetric and must be done judiciously.In all cases mitral valve competence should be tested by distending the ventricle with isotonic electrolyte(salin) solution. This maneuver will demonstrate any areas of residual leakage,which may be repaired by additional sutures (₈). The surgeon needs to observe the valve as many times as necessary before,during,and at the end of the procedure.The salin injection under pressure is favorable for checking the adequacy of the repair.Intraoperative salin test is safety but it was a 8% misleading ratio only (₉).

When leaflet mobility is normal,annular dilatation is corrected with a flexible annuloplasty ring,which is implanted using either an interrupted or continuous suture technique (₁). Mitral valve reconstructive surgery without annuloplasty entails a high incidence of early failures (₁₀). The object of the annuloplasty is :to correct the annular dilatation ¹ ;to increase free edge coaptation ² ; to reinforce the annulus after a leaflet resection procedure ³ ;and to prevent further annular dilatation ⁴ . Flexible ring annuloplasties were introduced based on the principles of mitral valve reconstruction introduced by Carpentier,particularly after the discovery of the three-dimensional continuous movements of the valve annulus (₂). A completly flexible Duran ring reduces the abnormally dilated annulus,allowing the three dimensional configuration of the mitral valve and was thought to be advantageous that the ring followed the changes of size and shape of the atrioventricular anulus in a physiological manner.Pump function was expected to improve because a flexible ring would interfere less with muscular contraction than would a rigid one. Moreover,the tension on the sutures would be less, which might reduce the chance of developing a partial dehiscence (₁₁). David et al. their data indicate that 2-3 months after mitral valve reconstruction left ventricular pump function is better in patients with a flexible ring than in patients with a rigid mitral ring (₁₀,₁₁). A consequence of preserving the left ventricular (LV) function is a reduction of the hospital mortality(3.3%),even lower in patients undergoing isolated mitral valve reconstruction (2.7%).

Patients with rheumatic disease have a higher incidence of thromboembolism than do those with degenerative or ischemic pathology(₁₂). For this reason we performed to treat with oral anticoagulant therapy during postoperative 3 months.

Atrial fibrillation (AF) is the most frequent rhythm disorder in population. It's frequency is 1% in general population and increases to 4% when age is over 60. This rate reaches to 50% in the cases operated rheumatic mitral valve disease (₁₃). If AF rhythm continues after mitral valve surgery, thromboembolic events increase and prevents the satisfactory function of heart. RF ablation especially during mitral valve surgery is a simple technique to be performed. Early results of cohort's is satisfying.At the one year follow-up time maintained sinus rhythm 88.9% (₁₄).

In conclusion;etiology plays a very important role in correction difficulties and in terms of late results affected by the progression of the disease. Rheumatic lesions,have been more difficult to treat conservatively and have a higher rate of repeat operations for early and late valve dysfunction,which oscillates between 10% and 27%(₁₀). Mitral valve reconstructive surgery with Duran flexible ring annuloplasty for rheumatic disease entails a low hospital mortality with satisfactory long-term clinical results, actuarial freedom from reoperation and it allows improvement of left ventricular function.

Correspondence to

Doç. Dr. Ufuk YETKİN 1379 Sok. No: 9,Burç Apt. D: 13 35220, Alsancak – İZMİR / TURKEY Tel: +90 505 3124906 Fax: +90 232 2434848 e-mail: ufuk_yetkin@yahoo.fr