CLINICAL EVALUATION OF MEDENG-2 / CARDIAMED PROSTHESIS IN THE MITRAL POSITION IN ISOLATED MITRAL DEFECT
More than 40 years have passed since the time when Albert Starr implanted the first mitral caged ball prosthesis into the patient on September 21, 1960. During that time hundreds of thousands of prosthetic heart valves have been implanted worldwide. Tens of mechanical valve models are available on the market, their designs undergo improvement continuously. Nonetheless, none of the modern cardiac prostheses is free from certain shortcomings, the so-called specific complications. Therefore, the designs of prosthetic heart valves continue to undergo improvements.
In recent years bileaflet prostheses “St. Jude Medical” and “Carbomedics” became very popular abroad because they are safe and have good hemodynamic characteristics, but they are very expensive. In Russia the production of similar prostheses began in 1994. MedEng-2 prosthesis is one of the models of prosthetic mitral valve.
In order to obtain comprehensive clinical evaluation of MedEng-2 prosthesis we have studied the outcomes of its use to correct rheumatic defect of the mitral valve in 218 sequentially operated patients.
Among the operated patients there were 54 male patients and 164 female patients ranging from 23 to 65 years of age (mean age was 50,5 years). Preoperatively, 88 (40,4%) patients had sinus rhythm, 130 (59,6%) patients had fluttering arrhythmia. According to classification of New York Heart Association (NYHA), 113 (51,8%) patients were in functional class Ш and 105 (48,2%) patients were in class IV at the moment of hospital admittance. Mean functional class of the operated patients was 3.57. Preoperatively, 119 patients had insufficiency of blood circulation at stage ПА and 99 patients had insufficiency of blood circulation at stage ПБ (according to N.D. Strazhesko and V.H. Vasilenko classification) 48 (22%) patients had calcification of the mitral valve (П - Ш degree), thrombosis of the left atrium was found in 20 (9,2%) patients.
Table 1. Characteristic of patient population (n-218)
| Age | 23-55 years (mean age 50,5 years) |
|---|---|
| Female patients | 164 (75,2%) |
| Male patients | 54 (24,8%) |
| Functional class Ш | 113(51,8%) |
| Functional class IV | 105 (48,2%) |
| Disorder of blood circulation ПА | 119(54,6%) |
| Disorder of blood circulation ПБ | 99 (45,4%) |
| Fluttering arrhythmia | 130 (59,6%) |
| Calcification П-Ш | Calcification П-Ш 48 (22,0%) |
| Thrombosis of the left atrium | 20 (9,2%) |
Mitral stenosis or its recurrence was diagnosed in 160 patients. 67 (30,7%) patients had recurrent mitral stenosis after previous transventricular commissurotomies. Of these, seventeen patients underwent closed mitral commissurotomies two times. In 39 cases the patients were operated in connection with combined mitral defect, and in 19 cases the patients were operated in connection with mitral valve insufficiency.
The following prosthetic valve sizes were used for mitral valve replacements: 25 mm, 27 mm, 29 mm, 31 mm.
Table 2. Sizes of the implanted prostheses.
| Valve size (mm) | Number of patients | % |
|---|---|---|
| 25 | 53 | 25,3 |
| 27 | 101 | 46,3 |
| 29 | 53 | 24,3 |
| 31 | 11 | 5,1 |
154 (70,6%) patients had been implanted with small size prostheses (valve size 25 and 27) due to the nature of valvular pathology. The majority of the operated patients had mitral stenosis or recurrent mitral stenosis.
The patients underwent comprehensive examination prior to operation, at the end of hospital period, and in the remote period (from 3.5 to 58 months). Hemodynamic parameters of the implanted prosthesis were evaluated with ultrasonography at the end of the hospital period (within 2 – 4 weeks after operation, upon the achievement of clinical stability). In the remote period hemodynamic parameters were studied at 3, 6, 12 months after operation, and later on yearly. There were two lethal outcomes among the operated 218 patients with Medeng-2 prostheses. Hospital mortality rate was 0.9%. There were no lethal outcomes among patients with preoperative functional class III. One patient aged 60 years old in preoperative functional class IV, operated in connection with mitral stenosis, had died due to rupture of the posterior wall of the left ventricle.
One female patient aged 59 years old in preoperative functional class IV with disorder of blood circulation stage П Б, operated in connection with second recurrent mitral stenosis, thrombosis of the left atrium, valve calcification of II degree, myocardial dystrophy, had died 56 days after operation due to sepsis, early prosthetic valve endocarditis.
Postoperatively, 41 patients had developed non-lethal complications.
Table 3. Non-lethal complications after mitral valve replacement
| Acute cardiovascular insufficiency | 7 |
|---|---|
| Hemorrhage | 3 |
| Cardiac arrhythmia | 7 |
| Encephalopathy | 3 |
| Pneumonia | 2 |
| Pleurisy | 7 |
| Mediastinum | 1 |
| Postcardiotomic syndrome | 6 |
| Gastrointestinal hemorrhage | 2 |
| Cholecysto-pancreatitis | 2 |
| Penetrating duodenal ulcer 1 TOTAL | 41 |
Cardiac insufficiency, which required inotropic stimulation for up to 3 days after operation, was diagnosed in 7 cases. Its development was due to an initial severe damage of myocardium in the patient operated in functional class IV. There were no such complications among the patients operated in functional class Ш.
Hemorrhage was diagnosed in 3 patients in the early hours after operation, which required resternotomy to stop it.
In seven cases the operation had caused transient cardiac arrhythmia, which required temporary electrocardiac stimulation to correct it.
In three patients the postoperative period was complicated by the development of pneumonia. Transient encephalopathy was observed in three cases. Effusion pleurisy, which required pleural puncture, had developed in 7 patients. Postcardiotomic syndrome with the signs of subfibrillation and pericarditis was observed in 6 patients. In one patient the postoperative period was complicated by the development of mediastenium, cured after resternotomy, sanation and drainage of pericardium.
Non-cardiac complications included stress penetrating duodenal ulcer with its urgent suturing, gastrointestinal hemorrhage in two patients stopped by conservative measures, and cholecystopancreatitis, which required cholecystectomy in one case, and, in the other case, was cured by conservative measures.
In most cases the developed postoperative complications were due to the initial severe health condition and the co-existing somatic pathology of the operated patients. There were no prosthetic valve-related complications in the early postoperative period.
Postoperatively all patients were subjected to full echocardiography examination including visual characteristic of prosthetic structures, Doppler echocardiography of the heart chambers, mitral blood flow, and blood flow in the pulmonary artery. The postoperative control studies had shown that the size of the left atrium and right ventricle decreased, as well as the systolic pressure in the pulmonary artery if compared to its preoperative level.
Table 4. Comparative characteristics of heart chamber sizes and hemodynamic parameters in patients, pre-and postoperatively
| Parameters preoperatively postoperatively | preoperatively | preoperatively |
|---|---|---|
| Diameter of the left atrium, mm | 53,97± 0,88 | 48,6б± 1,0 |
| EDS of the left ventricle, mm | 56,55± 1,03 52,87± 1,13 | 52,87± 1,13 |
| EF% | % 39,95± 1,15 | 51,52± 1,70 |
| Diameter of the right atrium, mm | 46,34± 0,91 | 33,51± 1,13 |
| Diameter of the right ventricle, mm | 18,12±0,70 | 17,00± 0,77 |
| Pressure inside the pulmonary artery, mmHg. | 37,94± 1,46 | 26,72± 2,01 |
EDS – End Diastolic Size Parameters of mitral blood flow were studied depending on the tissue annulus diameter of prosthesis.
Table 5. Hemodynamic parameters of the MedEng-2 prostheses in the mitral position depending on the tissue annulus diameter.
| Parameter | Valve size (tissue annulus diameter) | |||
|---|---|---|---|---|
| 25 | 27 | 29 | 31 | |
| Heart rate, beats/min. | 68±14 | 70±12 | 63±10 | 73±11 |
| Peak pressure, mmHg | 15,35±0,73 | 14,8± 0,51 | 13,77± 0,55 | 12,18± 1,33 |
| Mean pressure, mmHg | 6,24± 0,22 | 5,90± 0,24 | 5,33± 0,22 | 4,88±0,11 |
| EOA cm2 | 2,62+\-0,07 | 2,58+\-0,06 | 2,59+\-0,11 | 2,43+\- ОД1 |
For all valve sizes the pressure gradient decreased on the average for 37,1% and 21,5% respectively, and the area increased on the average for 89%.
216 patients were discharged from clinic on the average within three-week period. At the moment of discharge the signs of insufficient pulmonary and systemic circulation in patients disappeared or were significantly reduced and the tolerance to physical exertion increased. At discharge, doses of diuretics for all patients were reduced or completely discontinued. In most cases drug therapy was limited to supporting dosages of cardiac glycosides and anticoagulants to keep prothrombin index at about 50%. Thus, the positive outcome of surgery was obvious in the early time due to a radical improvement of the subjective condition of the patient and the positive dynamics of the main objective hemodynamic signs of the defect.
From 216 patients discharged from clinic 208 patients have been followed up postoperatively from 3.5 to 58 months, 8 patients were lost to follow-up. Mean follow-up time was 18.8 months, follow-up coverage was 96.3% (In total 432 patients-years). 4 patients had died within that follow-up time. In three cases the cause of late mortality was valve thrombosis, one female patient had died due to late prosthetic valve endocarditis. Late mortality rate was 1,9%.
Taking into account hospital mortality, the actuarial survival at 5 years postoperatively was 94,4± 4,4% (Fig. 1).
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Fig.1 Actuarial survival of patients after mitral valve replacement with MedEng prosthesis.
Analysis of postoperative functional status of patients after mitral valve replacement with MedEng-2 prosthesis is given in Table 6.
Table 6. Late postoperative functional status of patients with MedEng-2 prosthesis.
| Functional status | Number of patients | % |
|---|---|---|
| Functional class I | 20 | 9.2 |
| Functional class II | 132 | 61.0 |
| Functional class III | 41 | 19.0 |
| Functional class IV | 5 | 2.3 |
| Reoperation | 6 | 2.8 |
| Death | 4 | 1.9 |
| Unknown | 8 | 3.8 |
In accordance with the clinical evaluation we divided the patients into 3 groups: patients with the good, satisfactory, and bad surgery outcomes. Final assessment of the patient’s condition was based on the results of the last examination. The patients in postoperative functional class I or II were attributed to the group with good surgery outcome.
The patients in no higher than functional class III, but with subjective and objective hemodynamic improvements were attributed to the group with satisfactory outcomes. The patients in functional class IV with no significant postoperative improvements (in one case functional class went down from Ш to IV) were attributed to the group with unsatisfactory outcomes. The patients reoperated due to a disruption of prosthesis function were also included into this group. Four patients who had died at various times after operation were attributed to a special group.
Good outcome was observed in 152 (73.1%) patients, satisfactory outcome in 41 (19.7%) patients, and unsatisfactory outcome in 15 (7.2%) patients.
Table 7. Assessment of late surgery outcomes.
| Surgery outcome | Number of patients | % |
|---|---|---|
| Good | 152 | 73.1 |
| Satisfactory | 41 | 19.7 |
| Unsatisfactory | 15 | 7.2 |
Among the MVR patients who received MedEng-2 prosthesis, 182 (84,2%) patients improved one or more classes, on the average functional class improved from 3.5 to 2.1, fifteen patients stayed the same functional class, and one patient operated in class III showed a lower class, probably due to primary myocardial invalidization.
There were 7 events of prosthetic valve thrombosis among our patients: two events within the first year, four events within the second year, and one event within the third year. In three events the prostheses had tissue annulus diameter 27 mm, in four events - 29 mm. Four patients were successfully reoperated with re-implantation of prosthesis. The rest had died at home due to developed complications.
Paraprosthesis fistula was diagnosed in one female patient at 31 months postoperatively who had been operated in connection with recurrent mitral stenosis. She was successfully reoperated. One female patient was reoperated in connection with prosthetic valve endocarditis, which developed eight months after operation. She underwent re-implantation. However, she had died 4 months later due to recurrent infection.
In general, we are satisfied with the late outcomes of mitral valve replacement with MedEng-2 prosthesis. The majority of patients lead active way of life. Adequate correction of hemodynamics permitted them to improve their health condition and quality of life. Better surgery outcomes were observed in patients who were operated in functional class III. Specific complications turned out to be comparable to those, which occur with imported prostheses.
The clinical experience with the prosthetic valve "MedEng-2" in 218 patients with rheumatic defects of the mitral valve has shown good hemodynamic characteristics of the prosthesis. The prosthesis adequately corrects hemodynamics, is safe and no worse than foreign prostheses.
