Valvular Heart Diseases | Clinical Medicine

About this video

• Video Title: Valvular Heart Diseases | Clinical Medicine
• Channel: Ninja Nerd
• Speakers: Zach Murphy
• Duration: 00:46:42

Overview

This video provides a comprehensive overview of valvular heart diseases, focusing on mitral and aortic valve disorders. It explains the pathophysiology, complications, diagnostic approaches including murmur evaluation and echocardiography, and treatment strategies for conditions like mitral stenosis, mitral regurgitation, aortic stenosis, aortic regurgitation, and rheumatic fever. The lecture also touches upon prosthetic valve dysfunction.

Key takeaways

• Mitral Stenosis: Characterized by a narrowed mitral valve, leading to reduced blood flow from the left atrium to the left ventricle, commonly caused by rheumatic fever.
• Mitral Regurgitation: Occurs when the mitral valve doesn't close properly, allowing blood to flow backward from the left ventricle to the left atrium. Causes include dilated left ventricle or direct mitral valve damage.
• Aortic Stenosis: A stiffening and narrowing of the aortic valve, obstructing blood flow from the left ventricle to the aorta. Causes include bicuspid aortic valves in younger individuals and dystrophic calcification in older individuals.
• Aortic Regurgitation: The aortic valve fails to close properly, causing blood to leak back from the aorta into the left ventricle. Causes include dilated aorta (aneurysms) or aortic valve damage.
• Rheumatic Fever: An inflammatory condition triggered by strep throat that can damage heart valves, particularly the mitral and aortic valves, leading to rheumatic heart disease.
• Complications: Can include pulmonary edema, atrial fibrillation, stroke (from emboli), cardiogenic shock, and heart failure, varying depending on the specific valve and condition.
• Diagnosis: Involves evaluating heart murmurs, physical examination findings, echocardiograms, and sometimes cardiac catheterization.
• Treatment: Ranges from managing heart failure symptoms to surgical interventions like valve repair or replacement (TAVR, SAVR) and procedures like balloon valvuloplasty.
• Prosthetic Valve Dysfunction: Both mechanical and bioprosthetic valves can malfunction, leading to leaks or requiring specific management, such as anticoagulation for mechanical valves.

This video provides a detailed explanation of valvular heart diseases, covering their pathophysiology, complications, diagnosis, and treatment.

Introduction to Valvular Heart Diseases (VHDs): The video begins by defining VHDs and stating that the focus will be on left-sided valve disorders (mitral and aortic) as they are more common and higher yield for testing than right-sided ones (tricuspid and pulmonary). Tricuspid regurgitation is briefly mentioned as potentially being tested, especially in the context of IV drug abuse.

Pathophysiology:

• Mitral Stenosis (MS):

  • Defined as fibrosis, thickening, and sclerosis of the mitral valve.
  • This obstructs blood flow from the left atrium (LA) to the left ventricle (LV) during diastole.
  • The most common cause is rheumatic fever.

• Mitral Regurgitation (MR):

  • The mitral valve fails to close properly during systole, causing blood to flow backward from the LV to the LA.
  • Causes include:
    • Dilated left ventricle (e.g., in systolic heart failure or dilated cardiomyopathy), which stretches the valve leaflets apart.
    • Direct damage to the mitral valve, such as from infective endocarditis (common in IV drug users or those with prosthetic valves) or myxomatous degeneration (a genetic weakening of the valve leaflets, leading to mitral valve prolapse).

• Aortic Stenosis (AS):

  • The aortic valve is hardened and sclerotic, preventing adequate opening and obstructing forward blood flow from the LV to the aorta during systole.
  • Causes are age-dependent:
    • In patients < 70 years old: Often due to a congenital bicuspid aortic valve.
    • In patients > 70 years old: Typically due to dystrophic calcification (wear and tear over time).

• Aortic Regurgitation (AR):

  • The aortic valve doesn't close properly during diastole, allowing blood to flow backward from the aorta into the LV.
  • Causes include:
    • Dilation of the aorta (e.g., ascending aortic aneurysm), which pulls the valve leaflets apart.
    • Direct damage to the aortic valve, such as from infective endocarditis or aortic dissection.

• Rheumatic Fever:

  • Caused by Group A beta-hemolytic Streptococcus bacteria leading to pharyngitis (strep throat).
  • The body's immune response involves plasma cells producing autoantibodies (e.g., anti-streptolysin O, anti-DNase B).
  • These antibodies can cross-react with host tissues, particularly the heart valves (preferentially mitral, then aortic), joints, skin, and central nervous system.
  • This autoimmune process leads to inflammation and damage, resulting in rheumatic heart disease.
  • The Jones Criteria are used for diagnosis: two major criteria or one major and two minor criteria (Major: Carditis, Joints, Nodules, Erythema Marginatum, Sydenham's chorea; Minor: Fever, Arthralgia, Elevated ESR/CRP, Prolonged PR interval).

Complications:

• Mitral Stenosis (MS):

  • Blood backs up into the LA, increasing LA pressure. This transmits to the pulmonary veins and capillaries, leading to pulmonary edema (fluid in the lungs).
  • Symptoms: Dyspnea, paroxysmal nocturnal dyspnea (PND), orthopnea.
  • LA dilation occurs due to increased volume and pressure, which can alter atrial circuitry and lead to atrial fibrillation (AFib).
  • AFib in the enlarged LA can cause clot formation, leading to systemic emboli and events like stroke.

• Mitral Regurgitation (MR):

  • Similar to MS, blood backs up into the LA, increasing LA and pulmonary capillary pressures, leading to pulmonary edema and symptoms of left heart failure (dyspnea, PND, orthopnea).
  • In acute MR, the sudden increase in LA volume can overwhelm the system, causing a rapid drop in cardiac output and potentially cardiogenic shock.
  • In chronic MR, the LV may dilate to compensate, but eventually, forward output can decrease.

• Aortic Stenosis (AS):

  • Obstruction to LV outflow leads to decreased cardiac output and reduced systemic perfusion.
  • Symptoms are often described by the mnemonic "SAD":
    • Syncope (fainting due to transient reduction in cerebral perfusion).
    • Angina (chest pain due to reduced coronary perfusion).
    • Dyspnea (due to backup of pressure into the LA and lungs, similar to other valve diseases).
  • Characterized by a weak and delayed pulse (pulses parvis et tardus).
  • The increased afterload can lead to LV hypertrophy and eventually diastolic heart failure (HFpEF).

• Aortic Regurgitation (AR):

  • Blood flows back into the LV, increasing LV volume and preload.
  • In acute AR, this can cause a rapid drop in cardiac output and blood pressure, leading to cardiogenic shock.
  • The increased backflow leads to a widened pulse pressure (a large difference between systolic and diastolic BP), characterized by a "water hammer" pulse.
  • Increased LV volume and preload can lead to LV dilation.
  • Blood backs up into the pulmonary circulation, causing pulmonary edema and symptoms of left heart failure.

• Rheumatic Fever Complications: Beyond valve damage, complications can affect joints (arthritis), skin (nodules, erythema marginatum), and the CNS (Sydenham's chorea).

Heart Murmur Evaluation: Murmurs are characterized by location, timing (systolic/diastolic), intensity, radiation, and changes with maneuvers.

• Systolic murmurs: Aortic stenosis (crescendo-decrescendo, radiating to carotids), Mitral regurgitation (holosystolic, at apex, radiating to axilla).
• Diastolic murmurs: Aortic regurgitation (decrescendo, early diastolic), Mitral stenosis (mid-diastolic rumble with an opening snap at the apex). Maneuvers (standing, squatting, Valsalva, hand grip) can help differentiate murmurs by altering venous return (preload) and afterload.

Diagnostic Approach:

• Valvular Heart Diseases: Echocardiogram is the primary diagnostic tool to visualize valve structure, function, and chamber sizes. Cardiac catheterization may be used to measure pressures.
• Rheumatic Heart Disease: Diagnosis relies on the Jones criteria (major and minor) and serological tests for anti-streptococcal antibodies.

Treatment:

• General: Manage heart failure symptoms (diuretics, ACE inhibitors, etc.).
• Aortic Stenosis (AS): Transcatheter Aortic Valve Replacement (TAVR) is often preferred over Surgical Aortic Valve Replacement (SAVR), especially for older or high-risk patients. Indications include severe AS with symptoms, dropping LVEF, or significant pressure gradient despite medical therapy.
• Aortic Regurgitation (AR): Typically requires surgical valve replacement, especially in acute cases or chronic AR refractory to medical therapy.
• Mitral Stenosis (MS): Balloon valvuloplasty can be used for severe MS with a favorable valve morphology. Otherwise, surgical repair or replacement. Consider anticoagulation for AFib.
• Mitral Regurgitation (MR): Surgical repair or replacement is indicated for acute severe MR or chronic MR refractory to medical therapy.
• Rheumatic Fever: Treatment involves antibiotics (e.g., Penicillin G) to prevent further strep infections and management of resulting valve damage.
• Prosthetic Valve Dysfunction:
  • Mechanical valves: Require lifelong anticoagulation with warfarin (INR 2.5-3.5) due to high thrombogenicity. Dysfunction often involves paravalvular leaks.
  • Bioprosthetic valves: Do not typically require lifelong anticoagulation but are prone to degeneration over time, leading to transvalvular regurgitation or stenosis. A new murmur is a key sign of dysfunction.

This video aims to provide a thorough understanding of valvular heart diseases, emphasizing their clinical relevance and diagnostic/treatment pathways.

Rheumatic fever is presented as a significant cause of valvular heart disease, particularly affecting the mitral and aortic valves. Here's a full explanation based on the video:

Cause: Rheumatic fever is triggered by an infection with Group A beta-hemolytic Streptococcus bacteria, commonly manifesting as pharyngitis (strep throat).

Pathophysiology (The Autoimmune Reaction):

1. Initial Infection: The bacteria infect the pharynx.
2. Immune Response: The body's immune system responds by producing plasma cells, which then generate antibodies. These antibodies are intended to fight off the invading bacteria. Examples given are anti-streptolysin O and anti-DNase B antibodies.
3. Cross-Reactivity: A key aspect of rheumatic fever is that these antibodies, while targeting the bacteria, also have molecular similarities to certain tissues in the body. This leads to autoantibodies – antibodies that mistakenly attack the body's own tissues.
4. Target Tissues: These autoantibodies are known to attack several parts of the body:
   • Heart Valves: This is the most critical target concerning valvular heart disease. The antibodies preferentially attack the mitral valve (most commonly) and then the aortic valve. This attack leads to inflammation and damage of the valve leaflets and structures.
   • Joints: Autoantibodies can cause inflammation in the joints, leading to migratory polyarthritis (joint pain that moves from one joint to another).
   • Skin: They can cause specific skin lesions, such as subcutaneous nodules and erythema marginatum (a characteristic pink rash).
   • Central Nervous System (CNS): Damage to the basal ganglia can lead to involuntary, jerky movements known as Sydenham's chorea.

Rheumatic Heart Disease: When the autoimmune process leads to significant damage to the heart valves, this condition is termed Rheumatic Heart Disease. This damage can manifest as stenosis (narrowing) or regurgitation (leakage) of the affected valves.

Diagnosis (Jones Criteria): The diagnosis of acute rheumatic fever is typically made using the Jones Criteria, which requires evidence of a recent streptococcal infection (like a positive strep test or elevated anti-streptococcal antibody titers) along with specific clinical findings:

• Two Major Criteria OR
• One Major Criterion and Two Minor Criteria

The Major Criteria are:

• Carditis: Inflammation of the heart, including valve damage (leading to murmurs).
• Polyarthritis: Migratory inflammation of large joints.
• Subcutaneous Nodules: Firm, painless lumps on the skin, especially over bony prominences.
• Erythema Marginatum: A distinctive, non-itchy, pink rash with raised edges that often appears on the trunk and proximal extremities.
• Sydenham's Chorea: Involuntary, purposeless, jerky movements, often affecting the face, hands, and feet.

The Minor Criteria include:

• Fever
• Arthralgia (joint pain without swelling)
• Elevated Erythrocyte Sedimentation Rate (ESR) or C-Reactive Protein (CRP)
• Prolonged PR interval on an electrocardiogram (ECG)

Significance: Rheumatic fever is highlighted because it's a major, preventable cause of chronic valvular heart disease, particularly mitral stenosis. Understanding its autoimmune mechanism and diagnostic criteria is crucial for identifying and managing patients at risk.

Based on the video transcript, here's a summary of everything explained about Rheumatic Fever:

1. Cause:

• It originates from an infection with Group A beta-hemolytic Streptococcus bacteria.
• This typically leads to strep throat (pharyngitis).

2. Pathophysiology (The Immune Response):

• After the infection, the body's plasma cells become active.
• These cells produce antibodies (like anti-streptolysin O and anti-DNase B) to combat the bacteria.
• However, these antibodies can cross-react with the body's own tissues due to molecular mimicry. This results in autoantibodies.
• These autoantibodies then attack various tissues:
  • Heart Valves: This is the primary focus for valvular heart disease. The autoantibodies specifically target the heart valves, with a preference for the mitral valve followed by the aortic valve. This attack causes damage.
  • Joints: Leading to joint injury or inflammation.
  • Skin: Causing lesions like nodules and erythema marginatum.
  • Central Nervous System (Basal Ganglia): Leading to conditions like Sydenham's chorea (weird jerky movements).

3. Consequences (Rheumatic Heart Disease):

• The damage to the heart valves caused by this autoimmune process results in Rheumatic Heart Disease.
• This damage can lead to valve problems such as stenosis (narrowing) or regurgitation (leakage).

4. Diagnosis (Jones Criteria):

• The video mentions the Jones Criteria as the diagnostic framework.
• It requires evidence of a recent strep infection (either through testing or antibody levels).
• Along with the infection evidence, one needs:
  • Two Major Criteria OR
  • One Major Criterion and Two Minor Criteria
• Major Criteria: Joints, Heart (Carditis/Valve Damage), Nodules, Erythema Marginatum, Sydenham's Chorea.
• Minor Criteria: Fever, Arthralgia, Elevated ESR/CRP, Prolonged PR interval on ECG.

5. Clinical Presentation (Suspected Rheumatic Fever):

• The video suggests that if a patient presents with a history of strep throat and exhibits symptoms like joint pain, valvular disorders (detected via murmur), weird skin nodules, red rashes, and unusual movements (chorea), one should suspect rheumatic fever.

6. Treatment Considerations (Mentioned in the Treatment Section):

• If a patient is diagnosed with valvular heart disease because of rheumatic fever, they should be treated with Penicillin G. They may remain on this treatment for a significant duration.

In essence, the video explains rheumatic fever as an autoimmune consequence of a strep infection that damages heart valves, leading to valvular heart disease, and provides the diagnostic criteria and treatment principles for it.

This text explains the long-term consequences of Rheumatic Heart Disease (RHD), focusing on valve damage and its presentation:

RHD and Permanent Valvular Damage:

• RHD results from permanent damage to heart valves, most commonly the mitral valve, occurring after one or more episodes of Acute Rheumatic Fever (ARF).
• This damage often isn't clinically apparent until 10-20 years after the initial ARF diagnosis.
• However, it can appear sooner, especially if the patient experienced recurrent ARF episodes, leading to cumulative valve damage.
• The greatest risk factor for developing chronic valve damage is having carditis (inflammation of the heart) during the initial ARF episode.

Mitral Valve Involvement in RHD:

• The mitral valve is the most frequently affected valve in RHD.
• The mitral valve gradually thickens, develops fibrosis (scar tissue), and calcifies.
• This process leads to symptoms of heart failure, such as dyspnea (shortness of breath).
• Less commonly, it can cause cardioembolic stroke (a stroke resulting from a blood clot traveling from the heart).
• Management typically involves valvotomy (surgical procedure to cut or divide fused valve parts) or more invasive surgical valve interventions.

RHD Presentation Without Prior ARF Diagnosis:

• It's common for patients to show signs of RHD (like specific valve damage patterns) even if they don't recall a previous ARF diagnosis.
• This is likely due to a missed diagnosis of ARF during childhood or mild initial symptoms that were not recognized.

Distinguishing RHD Valve Damage from Other Causes:

• Characteristic RHD Calcification: In RHD, calcification typically affects the valve commissures (where the valve leaflets meet) more significantly, with less involvement of the valve annulus (the ring to which the leaflets are attached).
• Contrast with Age-Related Calcification: Age-related calcification, common in older individuals, primarily affects the posterior mitral annulus, with less involvement of the commissures. (This difference is noted as being illustrated in "figure 2," which is not provided here).
• Mitral Valve Prolapse (MVP) in RHD: RHD can cause MVP, usually involving prolapse of the anterior mitral valve leaflet. This needs to be differentiated from myxomatous degeneration, which is a more common cause of MVP (usually posterior leaflet prolapse) and prevalent in developed regions.