Prosthetic Valve Thrombosis: About 205 Patients

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Introduction
Rheumatic arthritis (RA) remains a public health problem in our country and in undeveloped countries, due to the prevalence of its main complication (rheumatic heart disease). Surgery of postrheumatic valvulopathy is a predominant proportion of cardiac surgery activity, despite all efforts to prevent RA and infectious endocarditis. Treatment is often a mechanical replacement, thromboembolic complications. In spite of the progress made in the design of new generations of mechanical prosthesis and the right prescription of anti-vitamin K therapy, prosthesis thrombosis of the heart remains a dreaded complication.
Thromboembolic and hemorrhagic accidents are the main complications of cardiac mechanical prosthesis (Thrombo-embolic peripheral accidents, Thrombosis of prosthesis (Occlusive or nonocclusive thrombosis)).
The rate of thrombo-embolic events is 2% patient-years in aortic position and 2.5% patient-years-in mitral position for bileaflet valve (4.16). The rate increases to 2.1% patient-years in the aortic position and 3.6% patient-years in the mitral position for the ball valve ( Figures  1-3) [1].

Problematic
Although therapeutic management of thrombosis is currently well codified ACC/AHA and ESC guidelines [2][3][4], it remains problematic in certain circumstances like thrombosis and pregnancy, early postoperative thrombosis and recurrent thrombosis.
The objective of this study is multiple: 1)Interest in early diagnosis for better therapeutic management.
2)Define a therapeutic strategy for heart prosthesis thromboses.
3)Better prevention of these accidents.
In this article we present the epidemiological, clinical features, imaging diagnosis, and treatment of 205 patients hospitalized in our department for prosthesis thrombosis and especially for a certain population whose medical treatment was instituted with favourable results.

Results
The femal sex predominates with a sex ratio of 0.25 (164 women and 41 men). The age of patients varied from 07 to 75 years. 28 patients had pregnancy during different age (17.39%).     Table 1). The approach of the heart by a vertical median sternotomy with aorto-bicaval cannulation 133 femoro-bicaval patients in 02 patients. 2)Redo in all patients (red, tridux or even quadridux) with these consequences (morbidity and mortality).

Choice of valvular substitute & anticoagulant treatment
In our practice the mechanical substitute is by far the most commonly implanted and this is in different valvular positions (Mechanical mitral valve: 93.65%, mechanical aortic valve: 98.52%, mechanical tricuspid valve: 71.42%) and this due to the unavailability of the biological substitute, rejection by patient's reoperation).
2) Socio-cultural and economic level. There are two types of patients: 1) Hemodynamic instability: High morbi-mortality.
The diagnosis of thrombosis must be premature: Functional symptoms of abrupt installation, in a valvular prosthesis wearer, must cause suspicion of valve thrombosis.

Choice of therapy
In the recommendations of the European Society of Cardiology, the management of prosthetic thrombosis depends on several factors (clinical stability, hemodynamic and ultrasound gradient and mobility of the fins) and distinguishes between obstructive thrombosis and non-obstructive thrombosis. According to ACC/AHA, the thromboses of the heart are distinguished from the thromboses of the right heart.
Choice of therapeutics: In our series, mechanical valve replacement is often performed: Mitral valve replacement in 113 patients (36 bioprothesis), Thrombectomy in 15 patients, Aortic valve replacement in 05 Patients, Tricuspid surgery in 02 Patients. Thrombectomy was the therapeutic choice despite the risk of rethrombosis, a risk that was raised in Roudaut's publication [5].
As for the thrombolysis, in our series, no patient benefited, two patients benefited from this therapeutic before their transfer to our center because both patients showed incomplete resolution and symptoms aggravation. In the ESC Guidelines: 1) Obstructive thrombosis of the left heart: Thrombolysis in a critical condition; the unavailability of surgery and in case of recent thrombosis and high operative risk in the absence of a critical situation.
2) Non-obstructive thrombosis of the left heart: at high surgical risk 3) ACC/AHA guidelines: Right thrombosis at failure of UFH. 4) ACC/AHA guidelines: Left thrombosis in case of recent thrombosis, NYHA I-II; Size<0.8 cm² and in case of failure of nonfractioned heparin. 5) Some authors recommend: Thrombolysis in the foreground in the absence of contraindications whatever the degree of obstruction; NYHA; size of the thrombus; reserving surgery in case of contraindication or failure of thrombolysis [6][7][8][9][10]. Others propose it in the event of signs of heart failure or in the absence of a surgical center: lower mortality/surgery [7][8][9][10][11]. 6) Right thrombosis: thrombolysis; Left thrombosis: surgery especially in case of chronic obstruction or left thrombosis [5]. Fibrinolysis is proposed in case of critical condition associated with recent obstruction in case of emergency surgery or in case of contraindication to surgery (low flow, redux, respiratory insufficiency) [5].
Fibrinolysis in stable cases after transoesophageal echocardiographic examination (Absence of large thrombus [5], but the inconvenient were embolic accidents.

Thrombosis and pregnancy
Pregnancy in a valve carrier is a major risk of thromboembolic event, in our series, out of a total of 205 thromboses, 28 Patients were in gestation of different age (17.39%). Twelve patients were operated on and six patients not operated (11.1%), among the factors favoring the occurrence, the following factors were noted: 1. Rural population socio-cultural and economic level. 2. Non-availability of bio-prosthesis for women in reproductive age. 3. Non-availability and high cost of non-fractioned heparin for the relay. 4. Low molecular weight heparin: Absence of marketing authorization in our country. 5. Women's insistence of second pregnancy. 6. Gynecologist/Cardiologist Collaboration. 7. Management of the anticoagulation during gestation: Deliberate arrest; under dosage; inter-laboratory results variability. 8. Lack of a center specialized in the management of this type of patient. Hence the value of bioprosthesis in any woman wishing to become pregnant and maintain of AVK during pregnancy (ESC, ACC/AHA: 5 mg).

Thrombotic recurrence
Thrombotic recurrence is a rare and severe complication, depending on the initial accident. In our series, we observed 18 rethrombosis in a variable delay (08.78%), the prognosis is more severe when it comes to rethrombosis associated with gestation, it is: 1) A second thrombosis in 16 patients, two patients received medical treatment, five patients with surgical treatment and seven patients with medical and surgical treatments.
2) Relay quality (availability and cost of relay, follow-up of relay efficiency).

4) Other gestations with mechanical substitute.
What attitude to postoperative thrombosis?
A postoperative thrombosis is a serious complication, in our practice we had to manage 33 Patients (16.09%).
The analysis of the patient files identified as favoring factors (Vice technique (Orientation of the fins, long and free ropes, inadequate anticoagulation, etc.), hence the interest of the prevention: 1) Surgical rigidity (preservation of the device under the valve).

3) Regular clinical and ultrasound follow-up.
Finally, there is a pertinent question, what attitude should be adopted in the face of postoperative thrombosis? Two options: medical treatment/surgical treatment (morbidity and mortality) [12][13][14].

Conclusion
The zero risk of heart prosthesis thrombosis does not exist despite the use of AVK whatever the type of mechanical prosthesis [15]. The correct indication of the type of valvular substitute (priority is a conservative gesture on valve replacement), the quality of anticoagulant therapy and its follow-up. The judicious choice of the valvular substitute taking into account the patient (age, sex), his socioeconomic level and desire for pregnancy can reduce the risk of thromboembolism accidents. «Prevention is better than cure», Hence the need to insist on: Prevention of rheumatic fever.