Cardiology >Prosthetic Health Valves

   Background

Prosthetic heart valves are artificial devices implanted to replace native heart valves that are stenotic, regurgitant, or infected. They restore unidirectional blood flow and cardiac hemodynamics. These valves can be mechanical or bioprosthetic and are used in the treatment of valvular heart disease. Though lifesaving, prosthetic valves carry risks of complications, including thrombosis, endocarditis, and structural failure.

II) Classification or Types

By Material:

• Mechanical Valves: Made from durable materials (e.g., pyrolytic carbon). Lifelong anticoagulation required.
  
  • Types: Bileaflet (e.g., St. Jude), Tilting-disc, Ball-in-cage
• Bioprosthetic Valves: Made from porcine, bovine, or pericardial tissue. Limited durability but less thrombogenic.
  
  • Types: Stented, stentless, homografts, autografts (Ross procedure)

By Position:

• • Aortic
  • Mitral
  • Tricuspid
  • Pulmonary

By Approach:

• • Surgical valve replacement
  • Transcatheter valve replacement (e.g., TAVR for aortic position)

III) Epidemiology

• • Increasing incidence due to aging populations and wider surgical/TAVR access
  • Aortic valve replacements most common; mitral valve prostheses second
  • Mechanical valves used more in younger patients (<50–60 years)
  • Bioprosthetic valves favored in older adults or those with contraindications to anticoagulation

   Etiology

I) What Causes Valve Replacement

• • Calcific aortic stenosis
  • Degenerative or ischemic mitral regurgitation
  • Rheumatic heart disease
  • Congenital valve defects (e.g., bicuspid aortic valve)
  • Infective endocarditis
  • Prosthetic valve dysfunction (requiring re-replacement)

II) Risk Factors for Prosthetic Valve Complications

• • Inadequate anticoagulation (mechanical valves)
  • Poor dental hygiene or invasive procedures without prophylaxis (endocarditis)
  • Prior infective endocarditis
  • Atrial fibrillation
  • Chronic kidney disease (accelerates structural degeneration)
  • Reoperation history

   Clinical Presentation

I) History (Symptoms)

• • Often asymptomatic post-surgery if functioning normally
  • Dyspnea, fatigue, chest pain, syncope, palpitations (in dysfunction)
  • Fever, malaise (suggestive of prosthetic valve endocarditis)
  • Embolic events (e.g., stroke, limb ischemia in valve thrombosis)

II) Physical Exam (Signs)

Vital Signs:

• • New or unexplained fever (infective endocarditis)
  • Tachycardia, hypotension (prosthetic valve dysfunction)

Cardiac Exam:

• • Prosthetic valve clicks (mechanical)
  • Murmurs suggesting regurgitation or stenosis
  • Systolic flow murmur is normal; new diastolic murmur is abnormal

Peripheral:

• • Petechiae, splinter hemorrhages (endocarditis)
  • Signs of heart failure: edema, elevated JVP, rales

   Differential Diagnosis (DDx)

• • Native valve disease recurrence
  • Paravalvular leak
  • Valve thrombosis
  • Prosthetic valve endocarditis
  • Hemolytic anemia (mechanical valve–related)
  • Stroke or TIA from emboli
  • Cardiac tamponade post-surgery

   Diagnostic Tests

Initial Tests:

Transthoracic Echocardiogram (TTE):

• • Evaluates valve motion, gradients, and potential regurgitation
  • Limited by prosthetic shadowing

Transesophageal Echocardiogram (TEE):

• • Superior for detecting vegetations, thrombi, paravalvular leaks

ECG:

• • Arrhythmias (e.g., atrial fibrillation)
  • May show ischemia or conduction defects

Chest X-ray:

• • Position of valve, signs of pulmonary congestion

Blood Cultures:

• • Essential if endocarditis suspected

Fluoroscopy:

• • Useful for assessing mechanical valve leaflet motion

CT/MRI:

• • CT for structural imaging (e.g., abscess, pannus)
  • MRI for cardiac function (less commonly used)

Anticoagulation Studies:

• • INR monitoring (target depends on valve type and position)

   Treatment

I) Medical Management

Anticoagulation:

• • Mechanical valves: lifelong warfarin (INR 2.5–3.5, depending on valve)
  • Bioprosthetic: typically anticoagulation for first 3–6 months
  • Bridging anticoagulation in perioperative or thrombotic risk situations

Heart Failure Management:

• • Diuretics, beta-blockers, ACE inhibitors if heart failure present

Infective Endocarditis:

• • IV antibiotics (6+ weeks)
  • Early surgical consultation for complications

Antiplatelet Therapy:

• • Often aspirin added to warfarin or in bioprosthetic valves post-op

II) Interventional/Surgical

Reoperation Indications:

• • Valve thrombosis unresponsive to anticoagulation
  • Structural valve deterioration (esp. bioprosthetic)
  • Endocarditis with abscess or dehiscence
  • Severe paravalvular leak

Thrombolysis:

• • Option for mechanical valve thrombosis when surgery is high risk

   Patient Education, Screening, Vaccines

• • Lifelong INR monitoring (mechanical valves)
  • Signs of valve dysfunction or embolism (dyspnea, fatigue, stroke symptoms)
  • Avoidance of trauma or risky activities with anticoagulation
  • Good oral hygiene; dental procedures may need prophylactic antibiotics
  • Medic alert bracelets/cards
  • Vaccinations:
    
    • Influenza (annual)
    • Pneumococcal vaccine
    • COVID-19 vaccine

   Consults

• • Cardiology: Valve monitoring, anticoagulation adjustment
  • Cardiothoracic Surgery: For prosthetic valve dysfunction or endocarditis complications
  • Infectious Disease: Prosthetic valve endocarditis
  • Hematology: Complex anticoagulation cases
  • Primary Care/Internal Medicine: Ongoing monitoring of comorbidities

   Follow-Up

• • Routine TTE: Annually or sooner if symptoms change
  • INR monitoring: Weekly to monthly, depending on stability
  • Dental surveillance and prophylaxis for high-risk procedures
  • Patient-reported symptom tracking: fatigue, palpitations, embolic signs
  • Echocardiography post-TAVR or surgical valve every 1–2 years