INTRODUCTION

In spite of the technological advances that the world has been experiencing over the last years, an ideal replacement valve has not been developed yet, principally in the case of children. The existing prostheses still present with complications which are difficult to control, especially calcification and rupture of biological prostheses and thromboembolism of the mechanical valves. This fact has led to authors more commonly utilizing repair techniques in the treatment of mitral valve reflux.

Since the initial studies of LILLEHEI [1] until other more recent investigations [2,3], we know that the walls of the left ventricle, the papillary muscles, the chordae tendineae, the cuspids and the mitral annuluses play an important role in the physiology of the left ventricular contraction. Additionally we know that there is a significant loss of ventricular function when parts of these structures are removed as occurs in valve replacement. The effort to preserve a mitral valve with reflux is even more important when the patient is less than 15 years old, as this patient is subjected to a greater number of future reoperations.

Even before the advent of cardiopulmonary bypasses in 1902, BURTON [4] proposed the possibility of mitral valvuloplasty. At this time some authors performed this operation, but without good results [5-7]. With the use of cardiopulmonary bypass, LILLEHEI et al. [8] successfully performed the first correction for mitral valve reflux, with plicature of the dilated mitral valve, under direct visualization. Many surgeons started to develop repair techniques, mainly of the mitral valve annulus, among whom were WERENDINO et al. [9], MCGOON [10], REED et al. [11] and WOOLER et al. [12]. However, the greatest contribution in the treatment of mitral valve reflux, by introducing the concept of mitral valve repair thereby demonstrating the importance of valve apparatus correction was CARPENTIER [13].

In Brazil, these procedures were first used by RIBEIRO et al. [14] and GREGORI et al. [15]. These authors developed several techniques employed in the patients of this study, such as neo-chordae, shortening of the lengthened chordae utilizing the leaflets [16], transplantation of the chordae of the tricuspid valve to the mitral valve [17], as well as an open prosthesis [18] for the remodeling of the mitral valve. CARVALHO et al. [19], POMERANTZEFF et al. [20] and BRAILE et al. [21] also made important contributions.

This study aimed at evaluating the postoperative evolution of under 15-year-old patients who underwent repair surgery for mitral valve reflux.

METHOD

Between May 1980 and November 2001, 117 under 15-year-old patients were submitted to repair surgery for mitral valve reflux.

This work was approved by the Research Ethics Committee of the Evangelic Hospital of Londrina.

All the patients' records and descriptions of surgeries were analyzed retrospectively.

The ages of the patients ranged from 1 to 15 years, with a mean of 10 years. Forty-three patients (36.8%) were male and 74 (63.2%) were female.

Eighty-seven patients (74.4%) only suffered from mitral valve reflux and 30 (25.6%) presented with associated stenosis. The etiology of the mitral reflux in 95 (81.2%) was rheumatic, in 16 (13.7%) congenital in 5 (4.3%) and infectious endocarditis and myxomatous degeneration in one (0.9%). All the patients were in functional classes III and IV.

The patients were operated on using cardiopulmonary bypass (CPB) and moderate hypothermia, with myocardial protection by intermittent declamping of the aorta at 15 minute intervals. The mean CPB time was 68 minutes (22 to 158 minutes) and of myocardial ischemia it was 38 minutes (8 to 108 minutes).

In the mitral valvuloplasty, all the characteristics that cause mitral valve reflux were analyzed, using the necessary techniques for its correction. The valve annulus was remodeled in all the patients, employing a Gregori-Braile or Carpentier rings or bovine pericardial strips. Other techniques such as lengthening of the chordae, commissurotomy and papillectomy were also used.

The mitral valve was evaluated during the operation under direct visualization after aortic declamping and with the heart beating. Apart from the reflux, it was considered important to create the most anatomically correct format possible of the valve after correction. Also valvar mobility post-implantation of the ring was considered to be important. After removing the cardiopulmonary bypass, direct auscultation of the left atrium was made using a sterilized stethoscope.

The functional class (NYHA) was evaluated in all the patients in the late postoperative period.

RESULTS

In all patients, the mitral valve was remodeled. Prostheses or support tissue were not used in only seven patients. In six (5.1%) bovine pericardium patches were used, in 35 (29.9%) Carpentier rings were employed and in the other 69 (59.0%) the Gregori-Braile ring was utilized. Annuloplasty in isolation was used in 22 patients (18.8%) and 95 (81.2%) required repair of the valvular cuspids and/or the subvalvar apparatus.

Sixty-six patients (56.4%) were submitted to shortening of the elongated chordae, 30 (25.6%) to commissurotomy and/or papillectomy, 11 (9.4%) to partial resection of the posterior leaflet, nine (7.7%) to resection of the anterior leaflet, six (5.1%) to plicature of the posterior leaflet, five (4.3%) to transposition of chordae, five (4.3%) to transference of chordae, five (4.3%) to sectioning of the retracted chordae, four (3.4%) to suturing of the orifices of leaflets and two (1.7%) to the removal of calcium of the anterior leaflet.

In association, the following procedures were also performed: tricuspid valvuloplasty in six patients (5.1%), closure of an interatrial communication in three (2.6%), ligature of a patent arterial canal in two (1.7%), aortic valve replacement in 10 (8.5%), aortic valvuloplasty in six (5.1%), resection of a subaortic fibrous annulus in one (0.9%), correction of the atrioventricular canal in one (0.9%) and Cox operation without cryoblation in one (0.9%).

Fifteen (12.8%) patients required reoperations. Among the 87 patients with isolated mitral valve reflux, 10 (11.5%) were re-operated and of the 30 patients with associated mitral stenosis, five (16.7%) needed to undergo reoperations. In four (26.7%) of the 15 patients who underwent reoperations a new plasty was performed and in 11 (73.3%) the valve was replaced. New rheumatic episodes occurred in five patients and active infectious endocarditis in one. No thromboembolic phenomenon occurred.

One hundred and thirteen patients (96.6%) survived, 104 (88.9%) with their native valves. Ninety-nine (84.6%) improved to functional class I or II (NYHA).

Hospital mortality was one patient (0.9%) with uncontrolled heart insufficiency and late mortality was three (2.6%) patients, with two of these deaths occurring during reoperations.

COMMENTS

Repair surgery for the treatment of mitral valve reflux is practically a universal consensus, especially in children in whom valve replacement is followed by a great number of reoperations.

The initial works presented techniques that aimed only at the treatment of the valvar annulus [9,12].

From the techniques proposed by CARPENTIER et al. [13] in 1969 and with a better understanding of the importance of all the valvar apparatus for ventricular function, several procedures have been presented to act on both the annulus [22,23] and the other structures of the mitral valve [15-17,24]. The late evolution of plasties also demonstrates the importance of the use of some type of prosthesis to remodel the annulus, whether it is flexible or rigid.

The superiority of plasty over valve replacement is also evidenced in the morbid-mortality rates, with a greater survival rate and better ventricular functional performance and with a lower number of reoperations [25,26]. Some authors suggest that valve repair, although it is not totally ideal, is better than valve replacement [27]. Mitral valve reflux can be secondary to multiple injuries of the commissures, leaflets and subvalvar apparatus, with a dilation of the mitral annulus seen in all patients. This is due to separation of its posterior part, as the anterior portion is restricted by the left and right fibrous trigones of the heart.

Annuloplasty was performed in all patients of this series, however only in 22 (18.8%) this was the only treatment, demonstrating that for the majority (81.2%) an association with other procedures is necessary. In only seven patients (6.0%) the annuloplasty was performed without a prosthetic ring or support tissues. In the last 69 (59.0%) patients, the Gregori-Braile ring was employed for remodeling purposes, which, as it is open, enables normal growth of the native annulus. This is important in children, as it allows better handling and correction of residual injuries even after its fixation.

CARPENTIER et al. [28] reported their experience with valvuloplasty over 10 years showing a hospital mortality rate of 4.2% and a late mortality rate of 7% in a series of 551 adult and child patients. However they did not find significant differences in the rates in different age ranges.

The index of reoperation (12.8%) was also similar to published data [28]. We should stress that, of the 15 re-operated patients, five presented with new episodes of rheumatic activity and one with bacterial endocarditis.

Hospital and late mortality was considered very low when compared to other authors. BORDIGNON et al. [29] reported hospital and late mortality rates of 4.3% and 8.6% respectively in a series of 20 children.

Thus, it is very hopeful to observe the late evolution, 113 patients (96.6%) are living, 104 (88.9%) with preserved native valves and 99 present with very good clinical evolution and are in functional classes I and II (NYHA).

CONCLUSION

Repair surgery for mitral valve reflux utilizing remodeling of the annulus with an open prosthesis in association with techniques of repair of the mitral valve apparatus is possible, presenting with results that support its use in under 15-year-old patients.

BIBLIOGRAPHIC REFERENCES

01. Lillehei CW, Levy MJ, Bonnabeau RC. Mitral valve replacement with preservation of the papillary muscles and the chordae tendineae. J Thorac Cardiovasc Surg 1964; 47:532-43.

02. David TE, Burns RJ, Bacchus CM, Druck MN. Mitral valve replacement of mitral regurgitation with and without preservation of chordae tendineae. J Thorac Cardiovasc Surg 1984; 88:718-25
[ Medline ]

03. Sarris GE, Cahill PD, Hansen DE, Derby GC, Miller DC. Restoration of left ventricular systolic performance after reattachment of the mitral chordae tendineae: the importance of valvular-interaction.J Thorac Cardiovasc Surg 1988; 95:969-79
[ Medline ]

04. Burton L. Preliminary note on the possibility of treating mitral stenosis by surgical methods. Lancet. 1902; 1:352-386.

05. Davila JC, Mattson WW Jr, O´Neill TJEl. A method for the surgical correction of mitral insufficiency. Sur Ginecol Obstet 1954; 98:407-12.

06. Harken DH, Ellis LB, Dexter L. The surgical correction of mitral insufficiency. J Thorac Surg 1954; 28:604-27.

07. Bailey CP, Jamison WL, Bakst AE. The surgical correction of mitral Insufficiency by the use of pericardial grafts. J Thorac Surg 1954; 28:551-603.

08. Lillehei CW, Gott VL, Dewall RA. The surgical treatment of stenotic or regurgitant lesions of the mitral and aortic valve by direct vision utilizing a pump-oxygenator. J Thorac Surg 1958; 35:154-89.

09. Merendino AK, Thomas GI, Jesseph JE, Herron PW, Winterscheid LC, Vetto RR. The open correction of rheumatic mitral regurgitation and or stenosis - with special reference to regurgitation treated by posterior-medial annuloplasty utilizing a pump-oxygenator. An Surg 1959; 1950:5-15

10. McGoon DW . Repair of mitral insufficiency due to ruptured chordae tendineae. J Thorac Cardiovasc Surg 1960; 39:357-62

11. Reed GE, Tice DA, Clauss RH. Asymmetric exaggerated mitral annuloplasty: repair of mitral insufficiency with hemodynamic predictability. J Thorac Cardiovasc Surg 1985: 49:752-61.

12. Wooler GH, Nixon PGF, Grimshaw VA. Experiences with the repair of the mitral valve in mitral incompetence. Thorax 1962; 17:49

13. Carpentier A. A new reconstructive operation for correction of mitral and tricuspid insufficiency. J Thorac cardiovasc Surg. 1971; 86:323-37.

14. Ribeiro EJ, Carvalho RG, Brofman PR. Operação Conservadora da Válvula Mitral. Arq Bras Cardiol 1983; 41:341-43

15. Gregori Jr. F, Takeda RT, Silva SS, Façanha LA, Méier MA. A new technique for repair of mitral insufficiency caused by ruptured chordae of the anterior leaflet. J Thorac Cardiovasc Surg. 1988; 96:765-68.

16. Gregori Jr. F, Silva SS, Façanha LA, Cordeiro CO, Aquino WK, Moure O. Preliminary results with a new technique for repairing elongated chordae tendineae of the anterior mitral valve leaflet. J. Thorac. Cardiovasc. Surg. 107:321-3, 1994.( Letter)

17. Gregori Jr. F, Cordeiro CO, Crotti UA, Hayashi SS, Silva SS, Gregori TEF. Partial tricuspid valve transfer for repair of mitral insufficiency due to ruptured chordae tendineae. Ann Thorac Surg 1999; 68:1686-1691.( Letter)
[ Medline ]

18. Gregori Jr., Silva SS, Hayashi SS, Aquino W, Cordeiro C, Silva LR et al. Mitral valvuloplasty with a new prosthetic ring. Eur J Cardio-Thorac Surg. 1994; 8:168-72

19. Carvalho RG, Giublin PR, Lopes CR, Mulinari L, Loures DRR Plástica da válvula mitral com emprego do anel de Gregori-Braile: Análise de 66 pacientes. Rev Bras Cir Cardiovasc. 1999; 13:295-316.

20. Pomerantzeff, PAM, Brandão CMA, Taber VN et al. Plástica da válvula mitral. Resultados aos 17 anos de experiência. Rev Bras Cir Cardiovasc. 1999; 14:185-190

21. Braile DM, Ardito RV, Pinto GH, Santos JLV, Zaiantchic M, Souza DRS, Thevenard R. Plástica mitral. Rev Bras Cir Cardiovasc. 1990; 5:86-98.

22. Duran CG, Ubago JLM. Clinical and hemodynamic performance of a totally flexible prosthetic ring for atrioventricular valve reconstruction. Ann Thorac Surg. 1976; 22:458-463.

23. Volpe MA;, Braile DM, Vieira EW, Souza DRS. Plástica mitral com anel maleável de pericárdio bovino. Arq Bras Cardiol. 2000; 75:318-388.

24. Frater RWN, Gabbay S, Shore D, Fractor J. Strom J. Reproducible replacement of elongated or ruptured mitral valve chordae. Ann Thorac Surg 1983; 43:14-28.

25. Camilleri LF, Miguel B, Bailly R et al. Flexible posterior mitral annuloplasty: Five-year clinical and Doppler echocardiographic results. Ann Thorac Surg 1998; 66:1962-7.

26. Craver, JM, Cohen C, Weintraub WS. Case- matched comparison of mitral valve replacement and repair. Ann Thorac Surg 1990; 49:964-69.
[ Medline ]

27. Kalil R, Luchese FA, Prates PR et al. Anulopastia sem suporte para tratamento da insuficiência mitral reumática. Rev Bras Cir Cardiovasc. 1992; 7:186-193

28. Carpentier A, Chauvaud S, Fabiani JN et al. Reconstruictive surgery of mitral valve incompetence. J Thorac Cardiovasc Surg 1980; 79:338-48.

29. Bordignon S, Kalil RAK, Sant'Anna JRM, Prates PR, Pereira EM, Nesralla IA. Resultado clínico tardio da anuloplastia mitral sem suporte em crianças e adolescentes. Rev Bras Cir Cardiovasc 1996; 11:263-9.
[ Lilacs ]