USMLE/COMLEX 3 - Valvular Disease

Here are key facts for USMLE Step 3 & COMLEX-USA Level 3 from the Valvular Disease tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. Aortic Stenosis Clinical Triad:

• Presents with angina, syncope, and dyspnea on exertion.
• Severe disease when valve area <1 cm²; requires valve replacement.

2. Aortic Regurgitation Management:

• Acute AR (e.g., from aortic dissection or endocarditis) requires emergent surgery.
• Chronic AR with LV dysfunction or symptoms → elective valve replacement.

3. Mitral Stenosis from Rheumatic Heart Disease:

• Presents with dyspnea, hemoptysis, atrial fibrillation, and embolic events.
• Treat with beta-blockers or rate control, anticoagulation if AF, and valvotomy or replacement in severe cases.

4. Mitral Regurgitation Management:

• Acute MR → treat underlying cause (e.g., chordae rupture from MI) and consider surgery.
• Chronic MR → surgery when symptomatic or LVEF <60% or LV end-systolic diameter >40 mm.

5. Indications for Valve Replacement:

• Symptomatic severe valve disease.
• Asymptomatic patients with signs of LV dysfunction or progressive dilation.
• Severe pulmonary hypertension or new-onset atrial fibrillation due to mitral stenosis.

6. Endocarditis Prophylaxis in Valvular Patients:

• Only indicated in high-risk valve patients (prosthetic valves, prior endocarditis, congenital heart disease) undergoing dental procedures that manipulate gingiva.

7. Mechanical vs Bioprosthetic Valve Selection: Mechanical*: Durable, requires lifelong warfarin (target INR 2.5–3.5). Bioprosthetic*: Shorter lifespan (\~10–15 years), but no long-term anticoagulation unless other indications. 8. Imaging Modality of Choice:

• Transthoracic echocardiography (TTE) is first-line.
• Transesophageal echo (TEE) if prosthetic valve or endocarditis suspected.
• CT or MRI for aortic root dilation evaluation.

9. Pregnancy Considerations:

• Mitral stenosis can worsen due to increased volume load.
• Bioprosthetic valves preferred in women planning pregnancy to avoid warfarin.

10. Medical Therapy for Valve Disease:

• Afterload reduction (ACE inhibitors, nifedipine) for chronic AR and MR.
• Avoid vasodilators in aortic stenosis (preload-dependent state).

11. Functional Mitral Regurgitation:

• Occurs due to LV dilation, not leaflet disease.
• Treat the underlying heart failure; surgery rarely indicated unless severe and symptomatic.

12. Valve Surgery Timing:

• Early surgery is preferred in asymptomatic severe disease with early signs of LV dysfunction or progressive dilation.

13. Atrial Fibrillation in Mitral Stenosis:

• Common due to LA enlargement.
• Requires rate control and anticoagulation (CHA₂DS₂-VASc score not applicable; anticoagulate regardless of score).

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14. Calcific Aortic Stenosis Pathophysiology:

• Caused by chronic hydroxyapatite deposition mimicking osteogenesis.
• Bicuspid valve accelerates the process (present in 1% of the population).

15. Mitral Valve Prolapse:

• Common cause of benign systolic murmur in young women.
• May progress to MR; surgery only if significant regurgitation or symptoms.

16. Prosthetic Valve Complications:

• Mechanical: thrombosis, hemolysis, endocarditis.
• Bioprosthetic: degeneration, structural failure.
• Both: prosthetic valve endocarditis, leakage, and paravalvular regurgitation.

17. Post-Surgical Monitoring:

• Routine echocardiograms for surveillance.
• Monitor anticoagulation (INR) in mechanical valves.

18. Mitral Annular Calcification (MAC):

• Associated with elderly and CKD.
• Can cause conduction abnormalities and increase risk of stroke and endocarditis.

19. Heart Sounds and Murmur Clues: Aortic stenosis*: Systolic crescendo-decrescendo. Mitral stenosis*: Opening snap + diastolic rumble. Aortic regurgitation*: Early diastolic decrescendo murmur. Mitral regurgitation*: Holosystolic murmur at apex radiating to axilla. 20. Medical Management Limitations:

• No medical therapy halts stenosis progression.
• Medical management is bridge to surgery or for symptom control.

21. Valve Disease in Heart Failure Workup:

• Always assess for valvular lesions in any new CHF patient using echocardiography.

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22. Low-Flow, Low-Gradient Aortic Stenosis:

• Occurs in patients with LV dysfunction where valve appears less severe.
• Use dobutamine stress echo to distinguish true vs pseudo-stenosis.

23. Indications for Balloon Valvuloplasty: Mitral stenosis*: Young, symptomatic, non-calcified valves.

• Not effective for calcific aortic stenosis in adults.

24. Peripartum Management of Valve Disease:

• Avoid ACE inhibitors and warfarin in pregnancy.
• Use beta-blockers, diuretics, or digoxin as needed.
• Consider percutaneous valvotomy for symptomatic mitral stenosis.

25. Pulmonary Hypertension from Valve Disease:

• Chronic mitral stenosis or regurgitation → elevated LA pressure → passive pulmonary HTN.
• Echo may show RV hypertrophy, TR, or RA dilation.