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Acute rheumatic fever (ARF) and rheumaticheart disease (RHD) remain major global health problems. The incidence of ARF and RHD remains high in developing countries.
Mitral stenosis (MS) is mainly caused by rheumatic diseases and is more likely to occur in women than men. MS takes decades to form, but it develops rapidly, and people in developing countries can cause severe pulmonary hypertension and congestive heart failure compared to people in developed countries.
Although MS is usually caused by rheumatic diseases, MS caused by severe calcification of the mitral annulus is increasingly severe in the elderly population. In addition, heart tumors, endocarditis, and congenital heart disease can also cause MS.
However, the treatment of these conditions is different from rheumatic mitralstenosis (RMS). This paper mainly reviews the treatment status and research progress of RMS.
epidemiology
Currently, the global burden of RHD remains high, with the Global Burden of Disease Study website reporting the global, regional and national burden of RHD from 1990 to 2015 in 2017. Although the health burden associated with RHD has declined worldwide, the high incidence of RHD remains in poor areas compared to developed countries.
Overall, there were an estimated 38 million to 40.8 million cases of RHD globally in 2017, with Oceania, South Asia and sub-Saharan Africa having the highest prevalence, disability and mortality. An estimated 266,200 to 303,300 people died from RHD in 2017. This figure may also be underestimated because of the lack of health care information systems in low- and middle-income countries.
ARF is a delayed autoimmune response to streptococcal infection and its long-term sequelae.
Children and adolescents aged 5 to 15 years are at greatest risk of developing ARF for the first time, however, the peak prevalence of RHD is between 25-45 years, reflecting the delayed detection of cases and the cumulative effect of ARF recurrence.
Worldwide, RHD remains the most common cause of MS. Among patients with RHD, 25% had isolated MS and 40% had MS combined with mitralregurgitation (MR). The progression of the disease is changeable, and the development of MS can last up to 20 years.
In most endemic areas, affected patients present with heart failure, with a 2-year case fatality rate of 16.9% in severe cases. Heart failure, infective endocarditis, atrial fibrillation, pregnancy-related complications, and stroke are the main complications of RHD.
The REMEDY study reported that 33% of patients had heart failure, 22% had atrial fibrillation, 7% had a previous stroke, and 4% had infective endocarditis.
pathogenesis
The natural history of RHD-related valve disease is varied, but in many cases, valve damage and dysfunction may be due to recurrent episodes of RF. RHD usually affects the left valve and has a large affinity for the mitral valve. It is associated with endothelial damage, especially since the structure of the valve may consist of two layers of endothelium covered by small connective tissue.
Acute rheumatic valvularitis presents with valvular regurgitation, but over time, chronic inflammation leads to valve fusion with or without valvular regurgitation resulting in valve stenosis.
MS caused by valve fusion, which can involve other parts of the mitral valve device to varying degrees, is a hallmark lesion in the late stage of RMS.
Pathophysiology
RMS is a classic RHD lesion characterized by leaf apical thickening, mitral valve fusion, and chordal contracture. The disease usually progresses slowly, with an average decrease in mitral valve area of 0.01 cm² per year, but varies greatly between populations and individuals. More than one-third of patients have no decrease in valve area for several years, and some patients may have a decrease in valve area of 0.3 cm² per year.
Early in the disease, the valve remains flexible and opens normally, then the valve leaflet is restricted and cannot open completely, resulting in the typical dome sign, and finally the mitral valve fuses to form a small central hole (fishmouth sign).
Untreated patients with progressive MS can present with dyspnea, fatigue, and haemoptysis, and can lead to serious complications such as pulmonary edema, systemic embolism, pulmonary hypertension, atrial fibrillation, and stroke.
Symptoms usually appear when the valve area shrinks to 1.5 cm², however, other factors such as sinus tachycardia, supraventricular tachycardia, atrial fibrillation, pregnancy, concomitant valvular disease, pulmonary hypertension, and anemia can lead to early onset of symptoms or cause symptoms disproportionate to the valve area.
The degree of MS is determined by mitral valve area. The normal valve area is 4~6cm2, mild MS≤2cm2, moderate MS≤1.5cm2, severe MS≤1cm2.
As the orifice area decreases, a higher left atrial pressure is required to maintain left ventricular filling and cardiac output. When left atrial pressure rises, pulmonary venous pressure rises, making breathing difficult. The left ventricle of MS is physiologically normal, although it may be small and underfilled. Left ventricular filling depends on left atrial pressure and diastolic filling timing.
With tachycardia (during exercise or with atrial arrhythmias), diastolic filling time is shortened, the role of left atrial systolic is weakened, resulting in insufficient left ventricular filling and worsening of symptoms of dyspnea.
Left ventricular underfilling (with decreased cardiac output) exacerbates other symptoms of heart failure, such as fatigue and exercise intolerance. Other hemodynamic consequences include elevated pulmonary artery pressure and symptoms of right heart failure. If left atrial stasis occurs, the risk of thrombosis and systemic embolism is also significantly increased.
diagnosis
An accurate and comprehensive assessment of the patient's medical history and symptom status, and a thorough physical examination is essential for diagnosis.
The diagnosis of RHD in individuals with episodes of ARF is detailed in the 2015 revision of the Jones criteria. However, the onset of most MS is usually insidious and insidious in the form of MS. Typical symptoms include fatigue, dyspnea, and decreased exercise tolerance. After the patient's condition worsens, they may change their lifestyle to compensate for the lack of exercise tolerance.
Other less common symptoms include haemoptysis, isolated chest pain (usually due to severe pulmonary edema), and hoarseness (left atrium compressing the recurrent laryngeal nerve).
MS face (pink-purple patches of the face) occurs occasionally and is thought to be due to systemic vasoconstriction. If the valve is still flexible enough, auscultation reveals an open valve click and a loud first heart sound.
As pulmonary hypertension worsens, a second heart sound splits. Murmurs occur during diastolic and are low-pitched. The murmur is most pronounced in the patient's left lateral decubitus position. The length of the murmur correlates with the severity of the stenosis. An electrocardiogram (ECG) and chest x-ray (CR) are helpful in the initial evaluation of a patient with MS.
ECG findings associated with MS include left atrial enlargement, atrial fibrillation, and right ventricular hypertrophy. CR often shows left atrial enlargement and pulmonary congestion. Left heart catheterization is used to measure pressure gradients and calculate valve area. Echocardiography is the primary way to diagnose and grade MS.
Echocardiographic findings include mitral lobular thickening, restriction, and fornix; Leaflet fusion, thickening, and calcification are common; The chordae will also thicken. The calculated flap area and average transfer pressure gradient help grade severity.
Other standard echocardiographic measurements include left atrial size, pulmonary artery pressure, left or right ventricular size and function, and assessing other valves for evidence of rheumatic changes.
All patients with MS should have an annual history evaluation and examination. Echocardiography should be performed every 3 to 5 years for mild MS, every 1 to 2 years for moderate MS, and annually for severe MS.
treat
Conservative treatment
Primarily targets complications of MS, including heart failure, atrial fibrillation, and prevention of thromboembolic disease. Patients with evidence of RHD should be treated with appropriate antibiotic prophylaxis. Most people with RHD are only mildly affected, and only a small percentage have more serious disease or complications that require intervention.
There are currently no drugs that have been shown to alter the natural course of severe chronic MS. For symptomatic MS, diuretics, long-acting nitrates, and β-blockers may temporarily improve symptoms.
Anticoagulation is necessary in the setting of left atrial thrombosis, permanent or paroxysmal atrial fibrillation with left atrial enlargement. Comprehensive antirheumatic therapy, including long-acting penicillin, is important.
In patients who are awaiting cardiac surgery or who are unable to undergo cardiac surgery with impaired contractility, ARB or ACEI drugs for heart failure may be effective. In most cases, surgery or intervention is recommended only if symptoms indicate or if there is a change in left ventricular function.
The goals of treatment are to maintain adequate hemodynamics, control existing arrhythmias, and treat or prevent concomitant heart disease (coronary heart disease, arrhythmias, and stroke).
Timely heart valve surgery can reduce the progression of heart failure, disability, and death.
Surgical treatment
Historically, CMV was the first effective intervention to treat MS in the history of closed mitralvalvotomy (CMV). Cutler and Levine reported the first successful CMV as early as 1923, and in 1954, the first CMV surgery was performed on the mainland.
A large number of studies at home and abroad have shown that CMV has a good short-term efficacy and can delay the valve replacement time, especially for women of childbearing age. However, RHD is a progressive disease that causes re-stenosis of the mitral valve, and most such patients require secondary surgery.
In a single-center study of 126 pregnant women with RMS, CMV raised 86% of women to grade 1 or 2 cardiac function 5 years after surgery. The restenosis rate for these women is an acceptable rate of 2% per year.
CMV is operated by finger separation, operated through the left atrial appendage or from the right side through the atrial septum, or with the help of instruments, which is simple and cost-effective, and is more widely used in less developed areas, and is gradually replaced by percutaneous mitral balloon captivotomy.
Percutaneous mitralballoonballoon valvotomy (PMBV)
PMBV relies on mechanical force to split the fused mitral valve, in 1984, Inoue first used PMBV to treat RMS, and in 1985, the mainland first introduced the method into China, and quickly promoted and popularized.
Inoue balloon technology is currently the most commonly used technology for PMBV. The forward technique is often used, that is, the catheter enters the right atrium after femoral vein puncture, passes through the atrial septum into the left atrium, and the balloon extension catheter enters the left atrium.
Esophageal ultrasound is used to determine balloon location and dilate the narrowed mitral orifice. The effect of surgery is related to the degree of adhesion of the leaflet leaflets. Mitral valve orifice area ≥ 1.5cm2 and MS with left atrial thrombosis, moderate to severe MR, valve calcification, etc., are considered absolute or relative contraindications to this procedure.
Most studies have shown that PMBV has similar indications and efficacy to CMV, and PMBV has less trauma, faster recovery, and is more acceptable to patients. If pregnant women have symptoms such as pulmonary hypertension, dyspnea, and heart failure, PMBV after 20 weeks of pregnancy can be significantly relieved and have little impact on pregnant women and fetuses.
However, the high proportion of mitral valve tears after PMBV surgery greatly increases the risk of valve replacement in patients, and for patients with thickened and calcified valves, the probability of acute complications is high, and the risk of restenosis after surgery is also high.
Direct mitral valve plasty (MVP)
RMS often has varying degrees of mitral valve stiffness, deformation, curling of the valve margin, junction, and subvalvular structural adhesion fusion. Rheumatic mitral valve repair has been reported significantly since the 70s of the 20th century. The 2021 ESA guidelines consider symptomatic rheumatic severe MS to be unsuitable for interventional MVP and recommend surgical repair.
There are many repair techniques, including direct junction incision, leaflet repair, chordal repair, and annular repair. Surgery is appropriate for each lesion, however, all MVPs should include annular repair, which is the cornerstone of MVPs.
Studies have shown that rheumatic MVP has significant advantages in early mortality, long-term survival, and valve-free complications, and the rate of second surgery is also low.
At present, the proportion of MVP in China is relatively small, and Professor Meng Xu has made more research and progress in this field, and proposed the three-step method of clinical pathological triparting and mitral valve plasty of rheumatic mitral valve in China, and guided the surgical operation according to the pathological classification. The medium- to long-term results of the molding are satisfactory.
Mitral valve replacement (MVR)
In the 40s of the 20th century, it was believed that the main cause of preoperative cardiac dysfunction in RMS patients was the fusion and sclerotic subvalvular structure, and advocated the removal of all mitral valves and subvalvular structural tissues.
With the deepening of research, some scholars have found that the annular structure composed of internal and external mediastinal ventricular muscles-athrole-leaflets-annulus is very important for maintaining postoperative left heart function and reducing the incidence of postoperative hypocardiopulmonary syndrome.
This annular structure can both limit diastolic hyperinflation of the left ventricle, help shorten the systolic left ventricle along the longitudinal axis, and effectively prevent left ventricular rupture. In 1964, MVR with subvalvular structure preservation was first introduced to reduce the incidence of postoperative hypocardiopulmonary row and left ventricular rupture.
Since then, MVR that preserves the mitral valve structure has gradually emerged. At present, it mainly includes: preservation of all valve leaflets and subvalvular structures and preservation of posterior and subvalvular structure MVR.
Preserving all valve lobes and subvalvular structures is theoretically almost perfect for patients, which can restore normal anatomical structure and hemodynamic state, but for most patients with MS, valve and subvalvular structures are calcified and adhesions, often accompanied by a decrease in the left ventricular cavity, and difficulty in prosthetic valve placement, which may lead to limited valve movement and even flap.
Studies have shown that MVR that preserves all subvalvular structures increases its adverse effect on downstream turbulent shear stress compared with simple preservation of posterior valve and subvalvular structures, which can cause unpredictable complications such as hemolysis and thrombosis, which may lead to left ventricular outflow tract stenosis in the long term and increase the risk of secondary surgery.
Compared with MS, the preservation of all valve leaflets and subvalvular structures is more suitable for patients with mitral regurgitation. Preservation of posterior and subvalvular structures can prevent papillary muscle damage, preserve the structure of the heart fiber stent, and prevent excessive expansion of the left ventricle.
The paradoxical movement of the posterior wall of the left ventricle and the ventricular septum is eliminated, thereby reducing the occurrence of serious complications such as hypocardiopulmonary syndrome and reducing the mortality rate of patients after surgery.
At the same time, retaining the MVR of the posterior valve is conducive to myocardial remodeling and cardiac function recovery, which is of great significance for improving the long-term effect of cardiac function. Studies have reported that MVR that preserves the submitral structure or reconstructs the continuity between the mitral annulus and the left ventricular wall by artificial chorda, is more conducive to the recovery of left ventricular function.
This procedure has become the most widely used MVR to preserve submitral structure. Even so, valve dysfunction and left ventricular outflow tract obstruction may occur postoperatively. If the prosthetic valve model is too small, it may lead to complications such as papillary muscle, chordal tendon rupture, and perivalvular leakage. Therefore, the requirements for skilled operation of the surgeon are very high.