Valvular Heart Disease

1. Summary

Valvular Heart Disease (VHD) is a significant cardiac condition affecting approximately 20 million people in the United States, primarily age-dependent. It involves structural or functional valve abnormalities leading to either regurgitation (failure to close competently) or stenosis (failure to open effectively). VHD progression is slow, often causing patients to unconsciously limit activity, emphasizing the need for careful history and detailed physical examination. Diagnosis relies on ECG, chest radiography, and transthoracic echocardiography (TTE), with classification into four stages (A-D) to guide monitoring and intervention. While medical therapy offers symptom palliation, surgical or transcatheter interventions are crucial for improving long-term survival, especially in severe cases. A multidisciplinary "heart team" approach is recommended for intervention considerations. Specific VHDs discussed include Aortic Stenosis, Aortic Regurgitation, Bicuspid Aortic Valve Disease, Mitral Stenosis, Mitral Regurgitation, Tricuspid Valve Disease, and conditions related to Prosthetic Valves and Infective Endocarditis (IE).

2. General Principles of Valvular Heart Disease (VHD)

• Definition and Prevalence: VHD is characterized by cardiac dysfunction due to "structural or functional valve abnormalities resulting from failure of the valves to either competently close (regurgitation) or effectively open (stenosis)." It affects around 20 million people in the U.S., with prevalence increasing with age (3-6% in those ≥65 years).
• Clinical Presentation: Patients often "limit their activity unconsciously in response" to slow progression. "Exertional dyspnea is the most common symptom," accompanied by others such as angina, syncope, palpitations, and edema, depending on lesion and severity.
• Diagnosis and Evaluation: Essential tests include "Twelve-lead ECG, chest radiography, and transthoracic echocardiography (TTE)."
• Staging: VHD is classified into four stages (A-D) based on risk factors, symptoms, lesion severity, ventricular response, pulmonary/systemic circulation effects, and rhythm changes (Table 22):
• Stage A (At risk): Patients with VHD risk factors.
• Stage B (Progressive and asymptomatic): Asymptomatic with progressive VHD.
• Stage C (Asymptomatic severe): Asymptomatic with severe VHD, categorized by compensated (C1) or decompensated (C2) ventricular function.
• Stage D (Symptomatic severe): Patients with VHD-related symptoms.
• Management Philosophy: "Medical therapy, although often effective for symptom palliation, has not been shown to prevent VHD progression or improve long-term survival." Surgery is "life-saving in select patients," requiring careful surgical risk calculation (age, morbidities, frailty, procedure-specific impediments). A "multidisciplinary approach with a heart team consisting of a cardiologist, a surgeon, and an interventional cardiologist is recommended" for intervention.

3. Specific Valvular Heart Diseases

3.1. Aortic Stenosis (AS)

• Etiology: Most commonly "degeneration of the valve that occurs with aging," or congenital (bicuspid aortic valve). Rheumatic disease and chest irradiation are other acquired causes.
• Pathophysiology: Chronic pressure overload of the left ventricle (LV) leads to concentric LV hypertrophy, myocardial interstitial fibrosis, diastolic dysfunction, and eventual systolic heart failure.
• Symptoms & Prognosis: "Exertional dyspnea, syncope, and angina are the most common symptoms," often not appearing until severe. "Among asymptomatic patients with severe aortic stenosis, 75% will die or develop symptoms within 5 years. Once symptoms occur, life expectancy is generally only 1 to 2 years."
• Diagnosis: TTE is the primary imaging modality. Severe AS is typically defined by "a small valve area (≤1.0 cm2), high peak velocity (>4 m/s), and/or high mean gradient (>40 mm Hg)." Subsets like low-flow, low-gradient AS require further evaluation (dobutamine echocardiography).
• Management: "Aortic valve replacement is a life-prolonging procedure." Indications include symptoms, LV systolic dysfunction (<50% ejection fraction) in asymptomatic patients, or concomitant cardiac surgery.
• Surgical Aortic Valve Replacement (SAVR) vs. Transcatheter Aortic Valve Implantation (TAVI): Both have similar survival rates (1-3% operative mortality). Choice depends on symptoms and surgical risk. TAVI is recommended for symptomatic patients >80 years or younger patients with life expectancy <10 years, and for high/prohibitive surgical risk patients with good post-procedure survival prospects. For 65-80 years, either is appropriate with shared decision-making.
• Medical Therapy: Statins are ineffective in slowing progression. Guideline-directed medical therapy is for coexistent hypertension or heart failure, with caution for vasodilators.

3.2. Aortic Regurgitation (AR)

• Etiology: Can be acute or chronic, stemming from aortic root pathology or valve pathology (e.g., endocarditis, bicuspid valve, rheumatic disease, trauma, dissection).
• Pathophysiology (Chronic): Volume overload leads to "progressive LV dilatation and eccentric hypertrophy," eventually causing symptoms like shortness of breath, fatigue, or angina.
• Clinical Findings (Chronic): Result from large stroke volume and LV dilatation, including "bounding peripheral pulses, displacement of the LV apex, and a diastolic decrescendo murmur."
• Clinical Findings (Acute): Abrupt volume overload can cause acute heart failure or cardiogenic shock. Bounding pulses may be absent, and murmurs softer/shorter.
• Diagnosis: TTE is indicated. Criteria for severe AR include specific jet width, vena contracta, regurgitation volume, and effective regurgitant orifice area. Aortic root abnormalities require CMR, CT, or TEE.
• Management:Chronic AR: Surgery (SAVR) is advised for symptomatic patients or those with LV dysfunction (EF ≤50% or indexed end-systolic dimension >25 mm/m2). TAVI is generally not performed for isolated severe AR.
• Medical Therapy: Dihydropyridine calcium channel blockers, ACE inhibitors, or ARBs for concomitant hypertension. ACE inhibitors/ARBs and β-blockers if surgery is not an option.
• Acute AR: Due to aortic dissection is a "surgical emergency." Other acute causes require surgery based on severity, symptoms, and hemodynamic stability.

3.3. Bicuspid Aortic Valve (BAV) Disease

• Prevalence: Affects 1-2% of the population.
• Pathology: Abnormal shear forces lead to "early degeneration of the valve, resulting in stenosis in most patients (up to 75%) and pure regurgitation in a small minority."
• Associated Abnormalities: Often accompanied by "aortic abnormalities, independent of the severity of aortic stenosis or regurgitation, and may be associated with aneurysm, dissection, or coarctation." Lifelong serial imaging of the ascending aorta and aortic arch is indicated if abnormalities are detected.
• Heritability: BAV is a "heritable abnormality," recommending screening for first-degree relatives.
• Management: Determined by predominant lesion and severity. Surgical repair of the ascending aorta is reasonable for patients undergoing valve surgery if t...