Reoperative mitral valve replacement: importance of preservation of the subvalvular apparatus

BACKGROUND: Preservation of the subvalvular apparatus has been demonstrated to be beneficial during first-time mitral valve replacement (MVR), but has not been fully examined in reoperative (redo) MVR. The purpose of this study was to analyze outcomes in a large cohort of redo MVR patients, focusing on the effect of subvalvular preservation on mortality. METHODS: We undertook a review of prospectively gathered data on patients undergoing MVR, with or without concomitant cardiac procedures, at our institution from 1990 to 1999. Predictors of mortality were determined by stepwise logistic regression. RESULTS: A total of 1,521 consecutive MVR patients were analyzed, of which, 513 (34%) had undergone one or more previous MV procedures. In-hospital mortality occurred in 6.9% of first-time MVR patients versus 9.0% in redo patients (p = 0.13). The number of prior MV operations ranged from one to five in redo MVR patients, with 115 patients (22% of redos) having two or more. In redo MVR patients, preservation of the native posterior subvalvular apparatus was performed in 103 patients (21%), whereas native anterior and posterior preservation was performed in 31 patients (6%). Gore-Tex neochordal construction was performed in 135 redo MVR patients (26%). Perioperative mortality occurred in 3.6% of redo MVR patients with a preserved subvalvular apparatus (native tissue and/or Gore-Tex reconstruction) versus 13.3% of redo patients without preservation (p < 0.001). Independent predictors of mortality in redo MVR patients were (in decreasing order of magnitude) failure to preserve the subvalvular apparatus, preoperative renal failure, previous stroke/transient ischemic attack, left ventricular dysfunction (left ventricular ejection fraction <40%), and urgent timing. CONCLUSIONS: Redo MVR can be performed with an acceptable risk of mortality. Although preservation of the subvalvular apparatus may increase operative complexity, we recommend subvalvular preservation in order to decrease the risk of early mortality.     

Clinical results of mitral valve replacement with and without preservation of the posterior mitral valve leaflet and subvalvular apparatus

In this study we attempted to investigate the importance of posterior leaflet preservation during mitral valve replacement (MVR). One hundred and forty randomly selected patients with isolated mitral insufficiency were studied, half of whom had MVR with preservation of the posterior leaflet (Group I), whereas in the other half conventional MVR was performed, without preservation of the posterior leaflet (Group II). Within these two groups there were no in hospital deaths, but 5 patients in Group II were admitted to the hospital with congestive heart failure and 3 of them died after approximately 6 months. Long term mortality rate was 4.2% in Group II. Ejection fraction (EF) decreased postoperatively from 56% to 50% in Group I (p less than 0.05), and from 59% to 49% in Group II (p less than 0.05). Fifteen patients in each group and aged below 30 with sinus rhythm and in the first functional capacity according to the New York Heart Association classification (NYHA) were subjected to exercise study, 18 months after the operation. After exercise EF increased from 47% to 64% in Group I and decreased from 51% to 47% in Group II. These findings suggested that MVR with the preservation of the chordae tendineae can be done with a low morbidity and mortality rate in the early and late postoperative period.     

Prosthesis of the mitral valve with full or partial preservation of the subvalvular apparatus

The article deals with the first experience in the USSR in using the method of mitral valve prosthesis with complete or partial preservation of the subvalvular apparatus. The operation was performed in 10 patients with mitral insufficiency or combined mitral valvular disease of various etiology. The advantages of employing during operation by this method mechanical prostheses with an obturator element which changes its position are pointed out. Only one patient needed inotropic support in the postoperative period. There were neither complications nor fatal outcomes.     

Hemodynamic evaluation of stentless mitral valve replacement

The purpose of this study was to evaluate the perioperative and postoperative hemodynamic function of recently introduced stentless mitral valves (SMVs). Forty-two selected patients who had received the SMV since 1997 had preoperative, postoperative, and follow-up transthoracic echocardiographic (TTE) examinations. Transesophageal echocardiography (TEE) was applied routinely during the operation as well as postoperatively if indicated. Adequate SMV function was seen in all patients perioperatively. Echocardiographic prediction of valve size and of papillary muscle distances was correct in 37 of 42 patients. Transvalvular blood flow velocities were 1.6 +/- 0.2 m/s postoperatively versus 1.8 +/- 0.3 m/s at 1 year and 1.7 +/- 0.3 m/s at 3-year follow-up. Mean transvalvular gradients were 4.3 +/- 1.6, 3.8 +/- 1.9, and 4.7 +/- 1.1 mm Hg, respectively. TEE and TTE are extremely useful to assist SMV implantation as well as for regular follow-up evaluation. The hemodynamic function after SMV implantation with preservation of the annulo-ventricular continuity is promising.     

Ways to improve the results of mitral valve prosthesis by preservation of the posterior cusp with the subcuspal structures

Prosthesing the mitral valve with preservation of the posterior cusp was performed in 156 patients. The domestic disk prostheses "Liks", "Emiks" and the bicuspid prosthesis "Medinzh" were used for the implantation. An additional correction of the tricuspid valve was made in 22 patients. The aortal valve needed the correction in 16 patients. The intrahospital lethality was 2.6%. The preservation of the posterior cusp prevents rupture of the posterior wall of the left ventricle, decreases risk of paraprosthetic fistulas and reduces frequency of the development of acute heart failure.     

Preservation of subvalvular mechanism at mitral valve replacement

According to literature data there is no common approach to method of mitral valve replacement with preservation of subvalvular structures. Results of 175 operations of mitral valve replacement are analyzed. The preservation of fibrous-papillary contact must not be regarded as the goal itself, but it must improve the clinical effect of operation. Further study of left ventricle remodeling at mitral valve disease and repair of physiological function after surgery permits to predict and improve the functional results in early and long-term postoperative period.     

Echocardiographic diagnosis of left ventricular outflow tract obstruction after mitral valve replacement with subvalvular preservation.

We describe two cases of left ventricular outflow tract obstruction after mitral valve replacement with complete retention of the subvalvular apparatus. The first patient deteriorated immediately after insertion of a high-profile bioprosthesis. In the second patient, chronic left ventricular outflow tract obstruction developed after the insertion of a low-profile mechanical prosthesis. The clinical course of left ventricular outflow tract obstruction after mitral valve replacement with complete retention of the subvalvular apparatus may differ greatly. Evaluation of the left ventricular outflow tract by perioperative transesophageal echocardiography or epicardial echocardiography is essential in the prevention and treatment of this complication.     

Expanding the use of total mitral valve preservation in combination with implantation of the CarboMedics heart valve prosthesis.

BACKGROUND: Preservation of the mitral valve and subvalvular apparatus was introduced into the clinic in the early sixties, but for two decades the standard technique for mitral valve replacement included excision of both leaflets and their attached chordae tendineae. Lately, increased emphasis has again been placed on retention of the mitral subvalvular apparatus during valve replacement because of its role on left ventricular function. METHODS: We have preserved the valvular and subvalvular mitral apparatus, when possible, in connection with mitral valve replacement during the last seven years and the present investigation (partly prospective and partly retrospective) was done with the aim of making up the results of our mitral preservation technique. In the period between January 1990 and December 1995, 30% of the patients who underwent mitral valve replacement had complete retention of all mitral tissue. In 1996, the percentage had increased to 50, and during the first seven months of 1997, 70% of the patients had complete retention of all mitral tissue. Since January 1997, we have exclusively used the CarboMedics mitral heart valve prosthesis. A total of 56 patients were identified to have had a CarboMedics heart valve prosthesis implanted. There were 33 men and 23 women with a mean age of 63 years, range 23-77 years. Coronary bypass was a concomitant procedure in 22 patients. In seven patients, both the mitral and aortic valves were replaced. A severely altered valve with thickened and or calcified leaflets, stenotic leaflets, or shortened, retracted and thickened chordae tendineae were not a contraindication for the procedure. Calcified plaques were removed. Adhesion between anterior and posterior leaflets was treated with sharp dissection. Valve and subvalvular tissue were preserved. The leaflets were reefed within the valve-sutures and compressed between the sewing ring and the native annulus when implanting the valve prosthesis. Chordal tension on the ventricle was thereby maintained and the chordae pulled away from the valve effluent. Echocardiography with measurement of ejection-fraction was performed preoperatively during the postoperative course in case of cardiac problems and on a routine basis 1 month after surgery and at various intervals when the patient was seen in the outpatient clinic. Left ventricular outflow tract gradients were measured during the postoperative course in case of cardiac problems and routinely 1 month postsurgically. RESULTS: Five patients died in the postoperative period and one patient had transient neurological symptoms. In none of the patients was death or transient neurological symptoms a consequence of the retention of mitral leaflets with subvalvular apparatus. The remaining 51 patients were all alive at follow-up. Postoperative echocardiography demonstrated a preserved left ventricular function and a left ventricular outflow tract without obstruction. CONCLUSIONS: We find that the described technique in combination with implantation of a CarboMedics heart valve prosthesis is very useful even in patients with a severely altered valve, when preserving the mitral leaflets with subvalvular apparatus during valve replacement. The technique is without procedure related complications and preserves left ventricular function without obstructing the left ventricular outflow tract.     

An improved mitral valve prosthesis

A Dacron velour–covered, Teflon-disc mitral valve prosthesis was developed in an effort to reduce thromboembolic complications of mitral valve replacement. A 12- to 28-month follow-up of 202 patients receiving these prostheses demonstrated only a 4.5% total incidence of such complications. However, a continuing search has been made for more durable materials. The most promising of these has been Pyrolite carbon, which now has been used for both the disc and the struts. Sacrifice of calves at intervals up to 12 months with scanning electron microscopical studies has demonstrated a disc and strut wear curve projecting 140 years prior to penetration of the Pyrolite carbon coating. Orifice and frustum areas of all sizes have been enlarged without change in mounting diameter. Clinical investigations of this prosthesis in several centers have been associated with as low an incidence of thromboembolic complications as that achieved with the Teflon-disc prosthesis. This improved prosthesis now has been released for general use.     

Mitral valve prosthesis with preservation of the chordae and papillary muscles in patients with mitral insufficiency

Mitral valve (MV) prosthetics was performed in 14 patients in its insufficiency. In MV replacement the chordopapillary apparatus (CPA) of the posterior cusp was left intact. The EMIKS or LIKS disk prosthesis was implanted in most cases (6 and 6 patients, respectively), the biological BAKS prosthesis was implanted in 2 patient. Orientation of the large semicircumference in the direction of the anterior or posterior commissure was the optimal orientation for the disk prostheses. Measurement of the parameters of hemodynamics on the operating table showed that reduction of the rigidity of the left-ventricular myocardium and the increase of the stroke index in patients with an intact chordopapillary apparatus of the posterior cusp differed significantly from those in patients with completely excised MV. Preservation of the CPA during MV replacement in patients with mitral insufficiency leads to reduction of the rigidity of the left-ventricular myocardium and improvement of its function immediately on the operating table.     

Thrombosis of mechanical mitral valve prosthesis

Obstruction of mechanical valve prostheses is a rare but potentially lethal complication following valve replacement surgery. Identifying the etiology and differentiation between thrombus, pannus, and vegetation obstructing the valve prosthesis can pose a diagnostic challenge. We report a patient who had an acute cerebral hemorrhage, developed a progressive mass lesion obstructing his mechanical mitral valve, and discuss contemporary diagnostic and management strategies.