ORIGINAL PAPERS 

MITRAL VALVE SURGERY IN DUBAI:  TEN-YEAR EXPERIENCE 

Hossam Eid, MD, Najib Al Khaja, Ph.D; Mohamed Abd-elaziz, MD; 
Tarek Abdelaziz, MD; Mohamed Bahr, MD
Cardiology and Cardiothoracic Surgery Center, Dubai Hospital, Dubai, UAE

Abstract
Introduction
Patients and Methods 
Results 
Discussion
Conclusion
References

Abstract

    This study was undertaken to highlight the epidemiology, the management and outcome of mitral valve surgery in Dubai. From January 1993 to March 2003, 200 patients underwent mitral valve surgery at Dubai hospital. The study group consisted of 140 males (70%) and 60 females (30%); the mean age was 38.2 ± 4. The etiology was rheumatic in 179 patients (89.5%), degenerative in 7 patients (3.5%), ischemic in 12 patients (6%) and congenital in 2 patients (1%). All patients had preoperative and postoperative clinical assessment for functional class (NYHA), radiological, electrocardiographic, echocardiographic, hematological and biochemical workup. Coronary angiography was performed routinely for patients who were 40 years and above, those at risk of coronary disease and those presenting with angina. Transesophageal echocardiography was routine pre and post bypass. 

    The operative technique was conventional sternotomy incision, cardiopulmonary bypass, bicaval canulation, aortic cross clamp, antegrade crystalloid cardioplegia in the first 60 patients, then ante grade blood Cardioplegia in 140 patients. Mean aortic cross clamp time was 50 ± 3.2 mins. For combined procedures. Mitral valve replacement was required in 140 patients (70%) of which 100 patients (50%) had isolated mitral regurgitation and 40 patients had mitral valve replacement with associated cardiac procedures. Biological valve prostheses were used in 6 patients (3%), monoleaflet mechanical prostheses in 6 patients (3%) and mechanical bileaflet prostheses in 128 patients (64%). Isolated mitral repair was performed in 34 patients (17%) and repair was associated with other cardiac procedure in 25 patients (12.5%).

    Hospital mortality was 5% (10 patients). Peri-operative complications included exploration for bleeding (11%), mediastinal respiratory complications (10%). At 6-months freedom from reoperation was (99%), freedom from thromboembolic complications was (98%), and freedom from endocarditis was (96%). At 3 years, 50% of patients were lost to follow-up. At 5 years freedom from death in the group who were followed-up was (96%), freedom from reoperation was (93%), freedom from thromboembolic events (91%) and freedom from endocarditis was (90%).  Heart Views. 2004;5(1):13-16 

© 2004 Gulf Heart Association 

Introduction 

    Mitral valve disease could be stenosis, regurgitation or combined regurgitation and stenosis. The etiology varies from congenital, rheumatic, degenerative, neoplastic and ischemic1. The current surgical procedures for mitral valve surgery include repair or replacement. The clinical introduction of valve prosthesis in the 1960's and increasing reliability of their hemodynamic characteristics and techniques of implantation in the mitral position seemed to have resolved the controversies concerning the treatment of mitral valve disease2. However, subsequent analysis of both short and long term results revealed that frequent use of prostheses often led to death and complications3. 

    Since the early days of cardiac surgery, repair of regurgitant mitral valve was pioneered with the perception that maintaining the normal architecture of the mitral valve is beneficial to the patient4. Further studies in the field of reconstructive surgery and the ideas of Carpentier led to unexpected renewal of interest in mitral valve reconstruction5. Reconstruction have been shown to have a number of advantages over valve replacement, not least the preservation of subvalvular apparatus, which is known to have beneficial effect on left ventricular function6. Although mitral valve repair is the procedure of choice to correct mitral valve disease of all types, up to 10% of patients who undergo mitral valvuloplasty require late reoperation for mitral valve dysfunction, which could be procedure related (58%), valve related (38%) or unknown (3%). In 79% of cases, reoperation will eventually be mitral valve replacement7. 

    The outcome if mitral valve repair is less successful in rheumatic than in degenerative disease. Failure is inversely related to the age of the patient8. Clinical factors such as age and functional status NYHA class before mitral valve operation are the most potent predictors of survival after surgery9. 

Patients and methods 

   From January 1993 to March 2003, two hundred patients underwent mitral valve surgery in Dubai hospital. Patients had full preoperative and post operative clinical assessments for NYHA class as well radiological (x-ray chest, PA and lateral views), electrocardiography, hematological and biochemical workup in the preoperative and immediately post operative in intensive care and for days 1, 3,5,7 post operative, during follow up at 2 weeks, 6 weeks and whenever necessary in the follow up period. 

    Transthoracic echocardiography (TTE) was performed in the preoperative assessment while intraoperative transesophageal echocardiography was done routinely pre-bypass and post bypass. Post operatively, patients underwent TTE at 3 months, then every 6 months during follow up. Coronary angiography was performed routinely for patients who were 40 years and above, those at risk of coronary disease, and those presenting with clinical manifestations of ischemic heart disease. 

    All patients had preoperative dental care, screening for HIV and HbSAg, and pulmonary function test. All gave informed consent for the surgical procedure. The exposure of the mitral valve was through left atriotomy (trans-septal approach was used in 4 cases, 2%). The mitral valve was assessed intraoperatively for surgical repair suitability in all patients. Mitral valve repair was attempted in patients whose mitral valve was deemed repairable. The repair technique depended on the pathological appearance of the valve and included: splitting of commissures, division of the secondary and tertiary chordae, chordal plication, chordal splitting, posterior leaflet plication, wedge resection and annuloplasty using annuloplasty rings (Duran or Carpemtier). Valve replacement was reserved for valves that were heavily calcified, infected, with primary chordal rupture, or severely damaged to be repaired. The prosthetic valves were either mechanical (monoleaflet or bileaflet) or biological, which was inserted using ethibond 2/0 interrupted sutures on Teflon pledget. 

    Antibiotic prophylaxis was cefuroxime one hour before incision and for 24 hours after. Post operative care was in the surgical intensive care with full hemodynamic monitoring. Patients were discharged on the 7th or 8th postoperative day. Postoperative physiotherapy and rehabilitation program continued for 3 months after surgery. The outpatient follow up was at 2 weeks, 6 weeks then monthly for 6 months and then every 6 months. The data were expressed in terms of mean standard deviation and comparison was done using student t-test; P value of <0.05% is statistically significant.

Results 

   Male to female ratio was 2.3:1, mean age was 38.2 years. Table 1 summarizes the indications for mitral valve surgery. 

Table 1.  Mitral valve surgery indications 

    The mean operative time was 180.8 min. The mean aortic cross clamp time was 50 ± 2.5 min. for isolated mitral procedure and 65 ± 3.2 mins for combined procedures. Table 2 summarizes the valve procedures. Associated cardiac procedures included coronary revascularization in 35 patients (17.5%), tricuspid valve repair in 30 patients (15%), closure of atrial septal defect in 2 patients (1%), insertion of permanent epicardial pacemaker in 1 patient (0.5%) and aortic valve repair in 2 patients (1%).

Table 2. Valve procedures 

    Patients who required mitral valve replacement (MVR) were 28 (20%), redo-operation, while 112 (80%) were primary operation. Table 3 shows the type of prosthetic valves used in the replacement group. 

Table 3. Types of prosthesis used 

    The hospital mortality was 10 patients (5%) and perioperative complications are shown in table 4. Survivors have shown improvement in their NYHA clinical class and improved their left ventricular function (ejection fraction) at 6 months follow up as shown in Table 5.

Table 5. Left ventricular function 6 months after MV surgery 

    The post operative follow up of patients continued. However, about 50% of survivors were lost to follow up at 3 years and another 20% at 5 years. The results of early 6-month and late 5 year follow up are summarized in Table 6.

Table 6. Results at 6 month & 5-year follow-up

Discussion 

    In our series of 200 patients with mitral regurgitation of various etiologies, 140 had mitral valve replacement and 60 patients had mitral valve repair. We believe, like others, that conservation of the mitral valve apparatus architecture totally or partially (replacement), preserves left ventricular function. Table 5 shows significant improvement of ejection fraction in isolated replacement cases in which we applied this concept. In agreement with others, patients with low preoperative ejection fraction, especially if associated with other procedure, we preferred mitral valve replacement to repair as the left ventricular ejection fraction decreases after valve repair compared with mitral valve replacement. This complication is associated with poor postoperative prognosis. The prognostic value of the preoperative ejection fraction is significant in patients with mitral valve repair and replacement10.

    The intraoperative assessment of the mitral valve by transesophageal echocardiography has decreased the perioperative complications and decreased the incidence of reoperation. Mitral valve surgery constituted about 17% of the cardiac surgery procedures in our unit during the study period. The outcome of mitral valve surgery depends on patient age, NYHA functional class, preoperative ejection fraction and presence or absence of coronary bypass associated procedure.

    Dubai is a cosmopolitan city with a large expatriate population of multi-ethnic origin, which constitute the main work force. Naturally, a high proportion of patients go back to their country, leading to a high percentage of patients being lost to follow up in our series at 3 and 5 years. This is the main limitation of our study. 
 

Conclusion 

    Mitral valve surgery has evolved with cardiac surgery in Dubai over the past 11 years. Although the number of patients is small, the variety of mitral procedures, the increasing number of redo cases, and the combination with CABG, the overall surgical outcome in our center is reasonably good.

References 

1. Carpentier A. Cardiac valve surgery - the "French correction" J. Thoracic Cardiovasc Surg.     1983; 86:323-337.

2.  Antunes MJ. Franco CG. Advances in surgical treatment of acquired valve disease. Current     opinion in Cardiology. 1996; 11(2): 139-154.

3.  Angell WW, Oury JH, Shah P. A comparison of replacement and reconstruction in patients     with mitral regurgitation. J. Thorac Cardiovasc. Surg.1987; 93:665-674.

4.  Lillehei CW, Gott VL, De Wall RA, Varco RL. Surgical correction of pure mitral insufficiency     by annuloplasty under direct vision. Lancet 1957; 77:446-449.

5.  Carpentier A, Deloche A, Dauptain J, et al. A new reconstructive operation for correction of     mitral and tricuspid insufficiency. J. Thorac Cardiovasc. Surg. 1971; 61:1-13.

6.  Lee EM, Shapiro LM, Wells FC. Importance of subvalvular preservation and early operation in     mitral valve surgery. Circulation 1996; 94(9): 2117 - 2123.

7.  Gillinov AM, Cosgrove DM, Lytle BW, et al. Reoperation for failure of mitral valve repair. J.     Thorac Cardiovasc Surg. 1997; 113(3); 467-473.

8.  Gometza B, Al-halees Z, shahid M, et al. Surgery for rheumatic mitral regurgitation in patients     below twenty years of age. Analysis of failures. Journal of Heart Valve Disease. 1996; 5(3):     294-301.

9.  Fleischmann KE, Wolff S, Lin CM, et al. Echocardiographic predictors of survival after surgery     for mitral regurgitation in the age of valve repair. American Heart Journal. 1996; 131(2):  281-     288.

10. Crawford MN, Souchek J, Oprian CA, et al. Determinants of survival and left ventricular     performance after mitral valve replacement. Circulation 1990; 81:1173-1181.

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