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Multiple and Mixed Valvular Heart Disease

Chapter 279 | Part 6: Disorders of the Cardiovascular System · Part 6 – Cardiovascular Disorders · Chapter 279

Key Clinical Points

  1. Proximal valve disease (e.g., mitral stenosis) can mask the hemodynamic impact of distal lesions (e.g., aortic stenosis).
  2. Atrial fibrillation in patients with mitral stenosis can cause a sudden, critical drop in cardiac output and worsening heart failure.
  3. The Gorlin formula is inaccurate for mixed aortic valve disease due to increased transvalvular flow velocities in regurgitation.
  4. Functional tricuspid regurgitation (TR) is common in significant mitral disease due to right ventricular and annular dilation; it features morphologically normal leaflets.
  5. Secondary mitral regurgitation (MR) results from LV remodeling and abnormal systolic tethering; it may not improve after isolated aortic valve replacement (AVR).
  6. Medical therapy is limited to diuretics for congestion, anticoagulation for atrial fibrillation, and blood pressure control; pulmonary vasodilators are generally ineffective.
  7. Significant paravalvular regurgitation following transcatheter aortic valve replacement (TAVI) is a significant risk factor for short- to intermediate-term death.
  8. Noncompliant ventricles (e.g., radiation, amyloid, obesity, diabetes) lead to earlier heart failure when volume loads from regurgitant lesions are added.
  9. The dominant valve lesion determines the natural history and treatment approach (e.g., severe AS dictates treatment even if MS is present).
  10. Mixed disease of a single valve is typically manifested by both systolic and diastolic murmurs.

1. DEFINITION & OVERVIEW

• Overview: Many acquired and congenital cardiac lesions may result in stenosis and/or regurgitation of one or more heart valves. • Rheumatic Heart Disease: Can involve the mitral (MS, MR, or both), aortic (AS, AR, or both), and tricuspid (TS, TR, or both) valves alone or in combination. • Mitral Annular Calcification: Can result in regurgitation (due to decreased annular shortening during systole) and mild or moderate stenosis (caused by extension of calcification onto the leaflets). • Secondary MR: May occur with severe AS due to LV remodeling; may not improve after isolated AVR. • Infective Endocarditis (IE): Aortic IE may involve the mitral apparatus via abscess formation/contiguous spread through the intervalvular fibrosa or by "drop metastases" onto the anterior mitral leaflet. • Other Causes of Mixed Disease: ◦ Mediastinal radiation: Often results in mixed stenosis and regurgitation of aortic, mitral, and tricuspid valves. ◦ Carcinoid heart disease: May cause mixed lesions of either or both the tricuspid and pulmonic valves. ◦ Ergotamines/Fenfluramine/Phentermine: Can rarely result in mixed aortic and/or mitral valve disease. ◦ Marfan syndrome: May have AR from aortic root dilation and MR due to mitral valve prolapse (MVP). ◦ Myxomatous degeneration: Can cause prolapse of multiple valves (mitral, aortic, tricuspid) without a specific connective tissue disorder. ◦ Bicuspid aortic or pulmonic valve: Results in mixed stenosis and regurgitation; bicuspid aortic valve is associated with aneurysm and predisposition to dissection.

2. ETIOLOGY & PATHOPHYYSICS

• Masking Effect: Proximal valve disease can mask the hemodynamic derangements of a more distal lesion. ◦ Example: Mitral stenosis (MS) reduces cardiac output (CO), masking the severity of aortic valve lesions. ◦ Risk: Atrial fibrillation (AF) in MS can lead to sudden worsening of underlying aortic disease. • Secondary Obstruction: Pulmonary vascular disease may act as a "secondary obstructive lesion in series." • Functional TR: ◦ Cause: Result of right ventricular and annular dilation; tricuspid leaflets are morphologically normal. ◦ Hemodynamics: Large systolic c-v waves in the RA pressure pulse; advanced cases show "ventricularized" RA waveforms. • Secondary MR: ◦ Cause: Related to changes in LV geometry (remodeling) and abnormal systolic tethering of leaflets. ◦ Morphology: Mitral valve leaflets and chordae tendineae are usually normal. ◦ Management: Improvement depends on relief of excess afterload via AVR; persistence is associated with poor outcomes. • Gorlin Formula Limitations: ◦ Problem: Not accurate in the setting of mixed aortic valve disease. ◦ Mechanism: Transvalvular systolic flow velocities are augmented in AR → LV-aortic Doppler-derived pressure gradient and murmur intensity are higher than expected for true systolic valve orifice size. ◦ Mitral context: Peak mitral valve Doppler E wave velocity is increased in severe MR, potentially masking the contribution of MS to LA hypertension.

3. CLINICAL FEATURES

• General: Patients with multiple/mixed disease may develop symptoms at a relatively earlier stage than those with single-lesion disease. • Symptom Drivers: ◦ Exertional dyspnea and fatigue: Result from elevated filling pressures, reduced CO, or both. ◦ Palpitations: May signify AF and identify mitral valve disease. ◦ Chest pain: Reflects LV oxygen supply/demand mismatch on a substrate of hypertrophy and pressure/volume overload. • Right Heart Failure: Abdominal fullness, bloating, and edema are late manifestations of advanced disease. • Tricuspid Valve Findings: TS prolongs the y descent in the RA pressure pulse; mitral findings typically predominate over tricuspid findings.

Physical Findings: • Mixed Single Valve: Manifested by both systolic and diastolic murmurs. • AS and AR: Mid-systolic crescendo-decrescendo murmur (AS) + blowing, decrescendo diastolic murmur (AR). ◦ Differentiation: Systolic murmur must end before S2 to distinguish from continuous murmurs (PDA or ruptured sinus of Valsalva). • Isolated MS and MR: Blowing holosystolic murmur and mid-diastolic rumble. • TS and TR: Mimic left-sided MS and MR, but differ with maneuvers (respiration). • Pulmonic Valve: Murmurs behave similarly to AS/AR; dynamic changes during respiration are key.

4. DIFFERENTIAL DIAGNOSIS

• AS/AR vs. Continuous Murmurs: ◦ PDA: Continuous murmur, best heard to the left of the upper sternum. ◦ Ruptured Sinus of Valsalva: Continuous murmur, often following an episode of acute chest pain. • Functional vs. Primary TR: ◦ Functional: Central origin, morphologically normal leaflets. ◦ Primary: Morphological changes in leaflets. • Bicuspid Valve: Early ejection click (common in young adults).

5. INVESTIGATIONS & DIAGNOSIS

  1. Transthoracic Echocardiography (TTE): Primary modality for diagnosis and characterization of morphology, function, calcification, chamber size, biventricular function, PA pressure, and great vessel dimensions.
  2. Transesophageal Echocardiography (TEE): Required for accurate mitral valve anatomy assessment and evaluation of IE.
  3. Cardiac Magnetic Resonance (CMR): Used when echocardiography is suboptimal; provides additional anatomic/physiologic information.
  4. Computed Tomography (CT): Used for complex IE (intracardiac structures) and planning for transcatheter valve implantation.
  5. Coronary CT Angiography: Noninvasive assessment of coronary anatomy before intervention.
  6. Invasive Hemodynamic Evaluation (Right/Left Heart Catheterization): → Indicated when: Discrepancy exists between clinical and noninvasive findings in a symptomatic patient. → Purpose: Characterize individual contributions of each lesion; measure PA pressures and calculate pulmonary vascular resistance (PVR).
  7. Additional Assessments: ◦ Exercise testing: Useful if functional limitation is not explained by resting TTE. ◦ Coronary angiography: Performed if indicated during invasive procedures.

6. MANAGEMENT & TREATMENT

  1. Clinical Strategy: Identify the dominant valve lesion to guide treatment (e.g., severe AS dictates management even if MS is present).
  2. Medical Therapy: ◦ Diuretics: For relief of congestion; titrate based on volume status. ◦ Anticoagulants: To prevent stroke and thromboembolism in patients with AF. ◦ Blood Pressure Control: Treat systemic hypertension (caution: may aggravate regurgitant lesions). ◦ Pulmonary Vasodilators: Generally ineffective for lowering PVR.
  3. Surgical and Transcatheter Intervention: ◦ Surgical AVR: Treatment for severe AS. ◦ Mitral Valve Repair: Performed for moderate-to-severe or severe secondary MR at time of surgical AVR. ◦ TAVI + TEER: Combination used in high surgical risk patients with severe AS and moderate-severe primary/secondary MR.
  4. Risk Mitigation: ◦ Paravalvular Regurgitation: Significant risk factor for short- to intermediate-term death after transcatheter AVR; requires careful monitoring. ◦ Secondary MR: Persistence of significant secondary MR after AVR is associated with impaired functional outcomes and reduced survival.

7. COMPLICATIONS & PROGNOSIS

• Dominant Lesion Influence: Natural history is primarily driven by the dominant valve lesion. • Paravalvular Regurgitation: Significant risk factor for short- to intermediate-term death following transcatheter AVR. • Persistent Secondary MR: Associated with impaired functional outcomes and reduced survival after AVR. • Noncompliant Ventricles: Small chamber size/noncompliance (radiation, amyloid, obesity, diabetes) leads to rapid rise in LV diastolic pressure and severe heart failure if any additional volume load is added. ◦ Specific Risk: Patients with significant AS and non-dilated LV will poorly tolerate sudden AR (e.g., from IE or paravalvular leak).

8. SPECIAL CONSIDERATIONS

• Noncompliant Ventricles: ◦ Radiation heart disease. ◦ Cardiac amyloid. ◦ Cardiomyopathy associated with obesity and diabetes. → These conditions result in inability of the LV to dilate in response to chronic AR or MR, leading to earlier onset of heart failure.

9. KEY PEARLS & HIGH-YIELD POINTS

• Masking: Proximal valve disease (MS) can mask distal lesions (AS/AR). • AF Risk: AF in MS can cause sudden, severe heart failure in patients with underlying AS. • Gorlin Formula: Inaccurate for mixed aortic disease due to increased flow in AR. • Functional TR: Characterized by central origin and morphologically normal leaflets. • Secondary MR: Result of LV remodeling; may be treated during AVR. • Paravalvular Leak: Significant risk factor for death after TAVI. • Noncompliant Ventricles: Radiation, amyloid, and obesity/diabetes limit LV adaptation to regurgitant volumes.