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Mitral stenosis

Updated : October 3, 2023





Background

Mitral stenosis is a heart valve disorder that primarily affects the mitral valve, one of the four valves in the heart. This valve is situated between the left atrium and the left ventricle and regulates blood flow between these two chambers.

The most common cause of mitral stenosis is rheumatic fever. This inflammatory condition can develop after an untreated or inadequately treated streptococcal infection, such as strep throat.

Epidemiology

Mitral stenosis is more prevalent in certain regions where rheumatic fever is more common. Historically, this includes parts of Africa, Asia, and Latin America. Developed countries with improved healthcare and antibiotic access have declined rheumatic fever and mitral stenosis. Mitral stenosis typically develops in individuals with rheumatic fever in childhood or adolescence. Therefore, it is often present in adults.

There may be gender differences, with some studies suggesting a higher prevalence in females, possibly due to differences in the development and progression of rheumatic heart disease. In regions where rheumatic fever has become less prevalent due to improved healthcare and living conditions, the epidemiology of mitral stenosis is changing.

In some developed countries, other causes of mitral stenosis, such as degenerative changes in the valve or congenital abnormalities, are becoming more significant. The availability of healthcare resources and awareness of rheumatic fever and its complications influence the identification and management of mitral stenosis. In some areas, screening programs may help detect and manage rheumatic fever early, preventing the development of mitral stenosis.

Anatomy

Pathophysiology

Mitral stenosis is a cardiac condition characterized by the narrowing of the mitral valve, located between the left atrium and the left ventricle of the heart. This narrowing restricts blood flow from the left atrium to the left ventricle, leading to physiological changes. Rheumatic fever is the most common cause of mitral stenosis, an inflammatory condition that can follow inadequately treated or untreated streptococcal infections, such as strep throat.

The mitral valve normally consists of two open and closed flaps to allow blood flow from the left atrium to the left ventricle. In mitral stenosis, the mitral valve undergoes pathological changes. The valve leaflets become thickened and may develop fibrous tissue. The thickening and fibrosis of the valve reduce the valve’s orifice. This narrowing obstructs the normal flow of blood from the left atrium to the left ventricle. As the mitral valve narrows, it impedes the blood flow from the left atrium into the left ventricle.

This leads to an increase in pressure in the left atrium. The increased pressure in the left atrium causes the left atrium to enlarge over time. This is a compensatory mechanism to accommodate the reduced flow of blood into the left ventricle. The elevated pressure in the left atrium is transmitted backward into the pulmonary circulation. This can lead to increased pressure in the pulmonary veins and pulmonary arteries.

Chronic mitral stenosis can result in pulmonary hypertension, where the blood pressure in the pulmonary arteries becomes elevated. This occurs due to the increased resistance to blood flow from the left atrium to the left ventricle. The right side of the heart may undergo hypertrophy in response to the increased pulmonary pressure. The enlargement of the left atrium and the impact on atrial tissue can predispose individuals with mitral stenosis to atrial fibrillation, an irregular and often rapid heart rate.

Etiology

Calcification of the Mitral Valve: As people age, the mitral valve can undergo degenerative changes, including calcification. This can result in a narrowing of the valve or a reduction in its ability to open fully.

Congenital Mitral Stenosis: Some individuals may be born with a narrow mitral valve, which is a congenital condition. In congenital mitral stenosis, the valve may not have developed properly during fetal development.

Rheumatic Fever: This is the leading cause of mitral stenosis. Rheumatic fever is an inflammatory disease that can develop after an inadequately treated streptococcal throat infection. It particularly affects the heart valves, leading to scarring and narrowing of the mitral valve.

Infective Endocarditis: This is an infection of the inner lining of the heart chambers and valves. If the mitral valve is affected, it can lead to scarring and narrowing.

Genetics

Prognostic Factors

Clinical History

Patients may have a history of rheumatic fever, an inflammatory condition that arises from inadequately treated or untreated streptococcal infections, particularly strep throat. Rheumatic fever is a major precursor to mitral stenosis. Individuals may have a history of recurrent streptococcal infections, indicating a potential predisposition to rheumatic fever. Patients may have a history of cardiac interventions, such as balloon valvuloplasty or surgical procedures, aimed at addressing mitral stenosis.

Dyspnea typically occurs during physical exertion but may progress to occur at rest as the condition worsens. A feeling of irregular or rapid heartbeats is often associated with the development of atrial fibrillation. Coughing up blood-tinged sputum may occur in severe cases due to increased pulmonary pressure. Chest discomfort may occur, especially in situations where oxygen demand is increased. Mitral stenosis typically has an insidious onset, developing gradually over time.

Once established, mitral stenosis is often a chronic condition. It may remain asymptomatic or cause mild symptoms for years before becoming more pronounced. The progression of mitral stenosis can vary among individuals. Factors such as the underlying cause, the degree of valve involvement, and the presence of associated conditions can influence the rate of progression. The duration of symptoms can also vary. Some individuals experience symptoms intermittently, while others have a more continuous and progressive course.

Physical Examination

During auscultation, the initial heart sound is often pronounced and may be palpable, attributable to the heightened force involved in the closure of the mitral valve. If severe pulmonary hypertension results from mitral stenosis, the pulmonic (P2) component of the second heart sound (S2) can become notably loud. An additional sound, an opening snap (OS), may follow the A2 component of the second heart sound (S2).

This occurrence corresponds to the forceful opening of the mitral valve when left atrial pressure surpasses that of the left ventricle. Subsequently, a mid-diastolic rumbling murmur, marked by presystolic accentuation, becomes audible post the opening snap. This low-pitched murmur is best discerned using the bell of the stethoscope at the apex. The murmur intensifies when the patient is in the left lateral decubitus position and during isometric exercise.

In advanced mitral stenosis, indications of right-sided heart failure become evident, including jugular venous distension, a parasternal heave, hepatomegaly, and ascites. Pulmonary hypertension may also manifest. Additional signs encompass atrial fibrillation, a left parasternal heave indicative of right ventricular hypertrophy from pulmonary hypertension, and a palpable apical beat.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Endocarditis

Left atrial myxoma

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

Prophylaxis for endocarditis is reserved for high-risk individuals and should be administered before dental procedures involving gingival tissue manipulation of the oral mucosa. High-risk patients include those with a prosthetic heart valve or prosthetic material from valve repair, a history of infective endocarditis, and those with cardiac valvuloplasty.

As for rheumatic fever prevention in patients with streptococcal pharyngitis, the primary approach involves using Benzathine penicillin. For individuals with normal sinus rhythm, medical therapy typically pursues symptomatic improvement. Diuretics alleviate congestion, while calcium channel blockers and beta-blockers address symptoms associated with elevated heart rate during exertion.

In cases of atrial fibrillation, the initial step involves rate control using AV node-blocking agents such as calcium channel blockers, beta-blockers, or digitalis. If a patient is unstable, direct current cardioversion is performed. If conversion to normal sinus rhythm is unattainable, the primary focus shifts to rate control. In stable patients, restoring normal sinus rhythm is favored over rate control, aiming to enhance functional capacity and overall quality of life.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Percutaneous mitral balloon valvuloplasty is an invasive intervention employed in managing mitral stenosis. This procedure is instrumental in ameliorating symptoms by enlarging the mitral valve area and diminishing the mitral valve gradient. Additionally, asymptomatic individuals presenting with pulmonary hypertension alongside moderate or severe stenosis are considered suitable candidates, provided favorable valve morphology is present and there is an absence of left atrial thrombus or moderate to severe mitral regurgitation.

In cases where percutaneous mitral balloon valvuloplasty is contraindicated or if the valve morphology is unfavorable, mitral valve replacement surgery becomes the recommended course of action. This is especially indicated in patients with symptomatic moderate or severe mitral stenosis. These recommendations are based on Class I evidence, with a Level of Evidence B, underscoring the importance of considering individual patient factors and characteristics in determining the most appropriate therapeutic approach.

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

Media Gallary

References

Mitral stenosis

Updated : October 3, 2023




Mitral stenosis is a heart valve disorder that primarily affects the mitral valve, one of the four valves in the heart. This valve is situated between the left atrium and the left ventricle and regulates blood flow between these two chambers.

The most common cause of mitral stenosis is rheumatic fever. This inflammatory condition can develop after an untreated or inadequately treated streptococcal infection, such as strep throat.

Mitral stenosis is more prevalent in certain regions where rheumatic fever is more common. Historically, this includes parts of Africa, Asia, and Latin America. Developed countries with improved healthcare and antibiotic access have declined rheumatic fever and mitral stenosis. Mitral stenosis typically develops in individuals with rheumatic fever in childhood or adolescence. Therefore, it is often present in adults.

There may be gender differences, with some studies suggesting a higher prevalence in females, possibly due to differences in the development and progression of rheumatic heart disease. In regions where rheumatic fever has become less prevalent due to improved healthcare and living conditions, the epidemiology of mitral stenosis is changing.

In some developed countries, other causes of mitral stenosis, such as degenerative changes in the valve or congenital abnormalities, are becoming more significant. The availability of healthcare resources and awareness of rheumatic fever and its complications influence the identification and management of mitral stenosis. In some areas, screening programs may help detect and manage rheumatic fever early, preventing the development of mitral stenosis.

Mitral stenosis is a cardiac condition characterized by the narrowing of the mitral valve, located between the left atrium and the left ventricle of the heart. This narrowing restricts blood flow from the left atrium to the left ventricle, leading to physiological changes. Rheumatic fever is the most common cause of mitral stenosis, an inflammatory condition that can follow inadequately treated or untreated streptococcal infections, such as strep throat.

The mitral valve normally consists of two open and closed flaps to allow blood flow from the left atrium to the left ventricle. In mitral stenosis, the mitral valve undergoes pathological changes. The valve leaflets become thickened and may develop fibrous tissue. The thickening and fibrosis of the valve reduce the valve’s orifice. This narrowing obstructs the normal flow of blood from the left atrium to the left ventricle. As the mitral valve narrows, it impedes the blood flow from the left atrium into the left ventricle.

This leads to an increase in pressure in the left atrium. The increased pressure in the left atrium causes the left atrium to enlarge over time. This is a compensatory mechanism to accommodate the reduced flow of blood into the left ventricle. The elevated pressure in the left atrium is transmitted backward into the pulmonary circulation. This can lead to increased pressure in the pulmonary veins and pulmonary arteries.

Chronic mitral stenosis can result in pulmonary hypertension, where the blood pressure in the pulmonary arteries becomes elevated. This occurs due to the increased resistance to blood flow from the left atrium to the left ventricle. The right side of the heart may undergo hypertrophy in response to the increased pulmonary pressure. The enlargement of the left atrium and the impact on atrial tissue can predispose individuals with mitral stenosis to atrial fibrillation, an irregular and often rapid heart rate.

Calcification of the Mitral Valve: As people age, the mitral valve can undergo degenerative changes, including calcification. This can result in a narrowing of the valve or a reduction in its ability to open fully.

Congenital Mitral Stenosis: Some individuals may be born with a narrow mitral valve, which is a congenital condition. In congenital mitral stenosis, the valve may not have developed properly during fetal development.

Rheumatic Fever: This is the leading cause of mitral stenosis. Rheumatic fever is an inflammatory disease that can develop after an inadequately treated streptococcal throat infection. It particularly affects the heart valves, leading to scarring and narrowing of the mitral valve.

Infective Endocarditis: This is an infection of the inner lining of the heart chambers and valves. If the mitral valve is affected, it can lead to scarring and narrowing.

Patients may have a history of rheumatic fever, an inflammatory condition that arises from inadequately treated or untreated streptococcal infections, particularly strep throat. Rheumatic fever is a major precursor to mitral stenosis. Individuals may have a history of recurrent streptococcal infections, indicating a potential predisposition to rheumatic fever. Patients may have a history of cardiac interventions, such as balloon valvuloplasty or surgical procedures, aimed at addressing mitral stenosis.

Dyspnea typically occurs during physical exertion but may progress to occur at rest as the condition worsens. A feeling of irregular or rapid heartbeats is often associated with the development of atrial fibrillation. Coughing up blood-tinged sputum may occur in severe cases due to increased pulmonary pressure. Chest discomfort may occur, especially in situations where oxygen demand is increased. Mitral stenosis typically has an insidious onset, developing gradually over time.

Once established, mitral stenosis is often a chronic condition. It may remain asymptomatic or cause mild symptoms for years before becoming more pronounced. The progression of mitral stenosis can vary among individuals. Factors such as the underlying cause, the degree of valve involvement, and the presence of associated conditions can influence the rate of progression. The duration of symptoms can also vary. Some individuals experience symptoms intermittently, while others have a more continuous and progressive course.

During auscultation, the initial heart sound is often pronounced and may be palpable, attributable to the heightened force involved in the closure of the mitral valve. If severe pulmonary hypertension results from mitral stenosis, the pulmonic (P2) component of the second heart sound (S2) can become notably loud. An additional sound, an opening snap (OS), may follow the A2 component of the second heart sound (S2).

This occurrence corresponds to the forceful opening of the mitral valve when left atrial pressure surpasses that of the left ventricle. Subsequently, a mid-diastolic rumbling murmur, marked by presystolic accentuation, becomes audible post the opening snap. This low-pitched murmur is best discerned using the bell of the stethoscope at the apex. The murmur intensifies when the patient is in the left lateral decubitus position and during isometric exercise.

In advanced mitral stenosis, indications of right-sided heart failure become evident, including jugular venous distension, a parasternal heave, hepatomegaly, and ascites. Pulmonary hypertension may also manifest. Additional signs encompass atrial fibrillation, a left parasternal heave indicative of right ventricular hypertrophy from pulmonary hypertension, and a palpable apical beat.

Endocarditis

Left atrial myxoma

Prophylaxis for endocarditis is reserved for high-risk individuals and should be administered before dental procedures involving gingival tissue manipulation of the oral mucosa. High-risk patients include those with a prosthetic heart valve or prosthetic material from valve repair, a history of infective endocarditis, and those with cardiac valvuloplasty.

As for rheumatic fever prevention in patients with streptococcal pharyngitis, the primary approach involves using Benzathine penicillin. For individuals with normal sinus rhythm, medical therapy typically pursues symptomatic improvement. Diuretics alleviate congestion, while calcium channel blockers and beta-blockers address symptoms associated with elevated heart rate during exertion.

In cases of atrial fibrillation, the initial step involves rate control using AV node-blocking agents such as calcium channel blockers, beta-blockers, or digitalis. If a patient is unstable, direct current cardioversion is performed. If conversion to normal sinus rhythm is unattainable, the primary focus shifts to rate control. In stable patients, restoring normal sinus rhythm is favored over rate control, aiming to enhance functional capacity and overall quality of life.

Percutaneous mitral balloon valvuloplasty is an invasive intervention employed in managing mitral stenosis. This procedure is instrumental in ameliorating symptoms by enlarging the mitral valve area and diminishing the mitral valve gradient. Additionally, asymptomatic individuals presenting with pulmonary hypertension alongside moderate or severe stenosis are considered suitable candidates, provided favorable valve morphology is present and there is an absence of left atrial thrombus or moderate to severe mitral regurgitation.

In cases where percutaneous mitral balloon valvuloplasty is contraindicated or if the valve morphology is unfavorable, mitral valve replacement surgery becomes the recommended course of action. This is especially indicated in patients with symptomatic moderate or severe mitral stenosis. These recommendations are based on Class I evidence, with a Level of Evidence B, underscoring the importance of considering individual patient factors and characteristics in determining the most appropriate therapeutic approach.

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