1.7 Valvular Heart Disease & Endocarditis Prophylaxis

Valvular heart disease, pericardial pathology, and aortic catastrophes demand a rigorous understanding of cardiovascular hemodynamics, physical examination findings, multimodal imaging interpretation, and definitive surgical versus percutaneous intervention thresholds.

1. Valvular Heart Disease

Aortic Stenosis (AS)

• Etiology: Calcific degenerative AS (most common in patients >65 years); Congenital Bicuspid Aortic Valve (presents at 40-60 years; requires screening first-degree relatives with echocardiography and evaluating the ascending aorta for associated aortopathy/aneurysm); Rheumatic valve disease.
• Classic Symptom Triad & Mortality:
  • Angina: Average survival ~5 years without valve replacement.
  • Syncope (exertional): Average survival ~3 years.
  • Dyspnea / Heart Failure: Average survival ~2 years.
• Physical Examination: Harsh, late-peaking crescendo-decrescendo systolic murmur loudest at the right 2nd intercostal space radiating to the carotids; pulsus parvus et tardus (delayed, weak carotid upstrokes); single or paradoxically split S2; diminished S2 intensity; S4 gallop.
• Echocardiographic Criteria for Severe AS:
  • Aortic Valve Area (AVA) <= 1.0 cm2 (Indexed AVA <= 0.6 cm2/m2)
  • Mean Transvalvular Gradient >= 40 mmHg
  • Peak Aortic Jet Velocity (Vmax) >= 4.0 m/s
  • Low-Flow, Low-Gradient Severe AS (LVEF <50%, stroke volume index <35 mL/m2, mean gradient <40 mmHg, AVA <=1.0 cm2): Perform low-dose dobutamine stress echocardiography to distinguish true severe AS (mean gradient rises >=40 mmHg while AVA remains <=1.0 cm2) from pseudo-severe AS (valve area increases to >1.0 cm2 as flow increases).
• Indications for Aortic Valve Replacement (SAVR vs. TAVR):
  • Class 1: All symptomatic patients with severe AS.
  • Class 1: Asymptomatic severe AS with LVEF < 50%.
  • Class 1: Asymptomatic severe AS undergoing other cardiac surgery (CABG or ascending aorta).
  • Class 2a: Asymptomatic very severe AS (Vmax >= 5.0 m/s or mean gradient >=60 mmHg) or abnormal exercise stress test (symptoms or fall in BP >10 mmHg).
  • SAVR vs. TAVR Selection: Transcatheter Aortic Valve Replacement (TAVR) is preferred in patients aged >=80 years or at high/prohibitive surgical risk; Surgical Aortic Valve Replacement (SAVR) is preferred in patients <65 years or life expectancy >20 years (due to bioprosthetic durability and mechanical valve option); shared decision-making for ages 65-80 years based on anatomy and valve durability.

Aortic Regurgitation (AR)

• Etiology: Aortic root dilation (Marfan syndrome, bicuspid aortopathy, thoracic aneurysm, hypertension, syphilis), infective endocarditis, aortic dissection, rheumatic heart disease.
• Physical Examination: High-pitched, blowing early diastolic decrescendo murmur heard best along the left 3rd-4th intercostal spaces with the patient leaning forward in end-expiration; wide pulse pressure (e.g., 170/45 mmHg); Austin Flint murmur (low-pitched mid-diastolic apical rumble caused by regurgitant jet striking the anterior mitral leaflet).
  • Eponymous Peripheral Signs: Corrigan/Water-hammer pulse (rapid bounding arterial pulse with quick collapse), Quincke's pulse (capillary pulsations in fingertips), Duroziez's sign (to-and-fro femoral bruit), Traube's sign (pistol-shot femoral sound), de Musset's sign (head bobbing with systole).
• Indications for Surgery in Severe AR:
  • Symptomatic severe AR.
  • Asymptomatic severe AR with LVEF <= 55% or progressive LV dilation (LV end-systolic dimension [LVESD] > 50 mm or LVESD indexed > 25 mm/m2, or LVEDD > 65 mm).

Mitral Stenosis (MS)

• Etiology: Almost exclusively caused by Rheumatic Heart Disease.
• Physical Examination: Loud S1, high-pitched Opening Snap (OS) following S2, and a low-pitched mid-diastolic rumbling murmur with presystolic accentuation heard best at the apex in the left lateral decubitus position. (A shorter A2-OS interval indicates higher left atrial pressure and more severe stenosis).
• Severity: Severe MS defined as Mitral Valve Area (MVA) <= 1.5 cm2 (very severe <= 1.0 cm2) and mean transvalvular gradient > 5-10 mmHg.
• Intervention: Percutaneous Mitral Balloon Commissurotomy (PMBC) is the first-line intervention for symptomatic severe MS with favorable valve morphology (Wilkins Echocardiographic Score <= 8: pliable leaflets, minimal subvalvular thickening, minimal calcification) in the absence of left atrial thrombus and absence of moderate-to-severe mitral regurgitation. Surgical mitral valve replacement is indicated if Wilkins score > 8 or if contraindications to PMBC exist.

Mitral Regurgitation (MR)

• Primary (Degenerative) MR: Mitral valve prolapse (MVP; mid-systolic click followed by late systolic murmur; click moves earlier with standing/Valsalva and later with squatting), ruptured chordae tendineae, endocarditis. Murmur is a blowing holosystolic murmur at the apex radiating to the axilla. Surgery (repair preferred over replacement) is indicated for symptomatic severe MR, or asymptomatic severe MR with LVEF <= 60% or LVESD >= 40 mm.
• Secondary (Functional) MR: Due to LV remodeling, apical displacement of papillary muscles, and leaflet tethering from dilated or ischemic cardiomyopathy. First-line therapy is optimal 4-pillar GDMT and CRT. Transcatheter Edge-to-Edge Repair (TEER / MitraClip) is indicated for persistent symptomatic NYHA II-IV secondary MR with LVEF 20-50% and LVESD <= 70 mm despite maximal GDMT (COAPT trial).

2. Infective Endocarditis Antibiotic Prophylaxis

Antibiotic prophylaxis prior to dental procedures is restricted to a very select group of highest-risk cardiac conditions. Routine prophylaxis for GI/GU procedures (colonoscopy, cystoscopy) is NOT recommended.

High-Risk Cardiac Conditions Requiring Prophylaxis

1. Prosthetic cardiac valves (mechanical, bioprosthetic, or transcatheter) or prosthetic material used for valve repair (rings, clips, chords).
2. Previous history of Infective Endocarditis.
3. Congenital Heart Disease (CHD):
   • Unrepaired cyanotic congenital heart disease (including palliative shunts and conduits).
   • Completely repaired congenital heart defect with prosthetic material or device during the first 6 months after the procedure.
   • Repaired CHD with residual defects at or adjacent to the site of a prosthetic patch or device.
4. Cardiac transplant recipients who develop cardiac valvulopathy.

Dental Procedures & Antibiotic Regimens

• Procedures Requiring Prophylaxis: Dental procedures that involve manipulation of gingival tissue, the periapical region of teeth, or perforation of the oral mucosa (e.g., dental scaling, extractions, root canal instrumentation).
• Standard First-Line Regimen: Amoxicillin 2 grams PO administered as a single dose 30 to 60 minutes before the procedure (or Ampicillin 2 g IV/IM).
• Penicillin-Allergic Regimens:
  • Cephalexin 2 g PO (if no history of anaphylaxis, angioedema, or hives to penicillins).
  • Azithromycin or Clarithromycin 500 mg PO.
  • Doxycycline 100 mg PO.
  • (Note: Clindamycin is NO LONGER recommended by AHA guidelines due to high rates of Clostridioides difficile colitis).