Residency · Residency · Internal Medicine
Valvular Heart Disease: When to Refer for Intervention
Pathophysiology
Aortic Stenosis
Calcific or degenerative aortic stenosis is the most common cause in elderly patients, arising from progressive calcification of either a trileaflet or bicuspid valve. Bicuspid aortic valve, the most common congenital cardiac anomaly (affecting 1-2 percent of the population), leads to accelerated calcification and typically becomes symptomatic 10 to 20 years earlier than trileaflet disease. Rheumatic aortic stenosis, caused by commissural fusion, is rarely isolated and usually accompanies concurrent mitral valve disease. Hemodynamically, progressive left ventricular pressure overload drives concentric hypertrophy, then diastolic dysfunction, and eventually systolic failure. Because the obstruction is fixed, cardiac output cannot increase appropriately with exertion.
Aortic Regurgitation
Acute aortic regurgitation -- from endocarditis, aortic dissection, or trauma -- is poorly tolerated and causes rapid decompensation. Chronic aortic regurgitation produces volume overload with eccentric left ventricular hypertrophy, which can be compensated for years before eventual decompensation. Common etiologies include bicuspid valve, aortic root dilation (Marfan syndrome, syphilis), endocarditis, and rheumatic disease.
Mitral Regurgitation
Primary (degenerative) mitral regurgitation arises from myxomatous degeneration with prolapse, flail leaflet, rheumatic disease, or endocarditis. Secondary (functional) mitral regurgitation results from left ventricular dilation with annular dilation and papillary muscle displacement, occurring in ischemic or dilated cardiomyopathy. Acute mitral regurgitation from chordal rupture, papillary muscle rupture (post-MI), or endocarditis constitutes a surgical emergency.
Mitral Stenosis
Rheumatic heart disease remains the most common cause worldwide, producing commissural fusion. In elderly patients, calcific mitral stenosis results from heavy mitral annular calcification. Progressive increases in left atrial pressure lead to left atrial dilation, atrial fibrillation, and pulmonary hypertension.
Tricuspid Regurgitation
Tricuspid regurgitation is most commonly functional or secondary to right ventricular dilation from pulmonary hypertension or left ventricular failure. Primary causes include endocarditis (especially in IV drug users), carcinoid syndrome, Ebstein anomaly, and radiation.
Clinical Presentation
Bedside Murmur Assessment
Aortic stenosis produces a crescendo-decrescendo systolic murmur at the right upper sternal border radiating to the carotids, accompanied by delayed carotid upstroke (parvus et tardus), diminished A2, and an S4. Aortic regurgitation creates an early diastolic decrescendo murmur at the left lower sternal border (best heard with the patient sitting up, leaning forward, in end-expiration), with wide pulse pressure, water-hammer pulse, and displaced point of maximal impulse. Mitral regurgitation presents as a holosystolic murmur at the apex radiating to the axilla, with an S3 if severe. Mitral stenosis produces a low-pitched diastolic rumble at the apex (best heard with the bell in left lateral decubitus position), with an opening snap (the earlier the snap, the more severe the stenosis) and a loud S1 (unless the valve is heavily calcified). Mitral valve prolapse is characterized by a mid-systolic click with or without a late systolic murmur; the click moves earlier with standing or Valsalva.
Dynamic Maneuvers
Valsalva and standing decrease preload, causing most murmurs to soften except those of hypertrophic cardiomyopathy and MVP (which become louder). Squatting increases both preload and afterload, softening HCM and MVP murmurs while making aortic regurgitation louder. Handgrip increases afterload, making mitral regurgitation and aortic regurgitation louder while softening aortic stenosis and HCM murmurs.
Symptom Assessment
The classical triad of aortic stenosis -- angina, syncope, and heart failure -- carries progressively worse survival without intervention: five years with angina, three years with syncope, and two years with heart failure. Aortic regurgitation causes exertional dyspnea and palpitations from hyperdynamic circulation. Mitral regurgitation produces dyspnea, fatigue, and atrial fibrillation. Mitral stenosis leads to exertional dyspnea, hemoptysis, and occasionally hoarseness (Ortner syndrome from left atrial compression of the recurrent laryngeal nerve).
Diagnostic Workup
Echocardiography
Echocardiography is the gold standard for valve assessment.
| Valve Lesion | Severe Criteria | Key Additional Parameters |
|---|---|---|
| Aortic Stenosis | AVA <1.0 cm², mean gradient >40 mmHg, peak velocity >4 m/s | Low-flow low-gradient: AVA <1.0 but gradient <40 (need dobutamine stress echo) |
| Aortic Regurgitation | Vena contracta, holodiastolic flow reversal in descending aorta | Regurgitant volume, pressure half-time |
| Mitral Regurgitation (primary) | Vena contracta ≥7 mm, EROA ≥0.4 cm², regurgitant volume ≥60 mL | Flail leaflet, ruptured chordae |
| Mitral Regurgitation (secondary) | EROA ≥0.2 cm², regurgitant volume ≥30 mL | LV dilation, annular dilation |
| Mitral Stenosis | MVA <1.0 cm², mean gradient >10 mmHg | Wilkins score for PMBC candidacy |
Severe aortic stenosis is defined by an aortic valve area below 1.0 cm2, a mean gradient above 40 mmHg, or a peak velocity above 4 m/s. Low-flow, low-gradient aortic stenosis -- where the valve area is below 1.0 cm2 but the gradient is below 40 mmHg because of reduced LV function -- requires dobutamine stress echocardiography to differentiate true severe AS from pseudo-severe disease. Paradoxical low-flow, low-gradient AS occurs with a normal ejection fraction but a small, hypertrophied LV with low stroke volume. Severe aortic regurgitation is identified by vena contracta, regurgitant volume, and holodiastolic flow reversal in the descending aorta. Severe mitral regurgitation thresholds include a vena contracta of 7 mm or larger, an effective regurgitant orifice area (EROA) of 0.4 cm2 or larger for primary (or 0.2 cm2 for secondary), and a regurgitant volume of 60 mL or more. Severe mitral stenosis is defined by a mitral valve area below 1.0 cm2 with a mean gradient above 10 mmHg.
Additional Testing
Cardiac catheterization is reserved for cases where non-invasive assessment is discordant or equivocal. Exercise stress testing can unmask symptoms or hemodynamic compromise in asymptomatic severe aortic stenosis. CT calcium scoring is emerging as a tool for confirming severe AS when echocardiography is equivocal. Cardiac MRI quantifies regurgitant volumes and assesses myocardial fibrosis. BNP has prognostic value in asymptomatic severe aortic stenosis.
Management
Aortic Stenosis
Symptomatic severe aortic stenosis requires surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR). TAVR was initially approved only for high and prohibitive surgical risk patients but has been expanded to low-risk patients based on the PARTNER 3 and Evolut Low Risk trials. Asymptomatic severe AS warrants intervention when the ejection fraction falls below 50 percent, the exercise test is positive, disease is very severe (peak velocity above 5 m/s), or there is rapid progression. No medical therapy slows AS progression. Vasodilators should be used cautiously, though nitroprusside can be carefully employed in decompensated severe AS. Balloon valvuloplasty serves only as a bridge to definitive therapy because rapid restenosis occurs.
Aortic Regurgitation
Surgery for chronic severe AR is indicated when the patient is symptomatic or, if asymptomatic, when the ejection fraction drops to 55 percent or below or the LV end-systolic dimension exceeds 50 mm. Vasodilators (nifedipine, ACE inhibitor/ARB) are used for chronic AR with hypertension or when surgery is not feasible, but they should not delay necessary surgery. Acute severe AR (from endocarditis or dissection) requires emergent surgery with medical stabilization using nitroprusside and inotropes. An intra-aortic balloon pump is contraindicated because it augments regurgitation in diastole.
Mitral Regurgitation
Primary severe MR warrants surgery when symptomatic, or when asymptomatic with an ejection fraction of 60 percent or below, LV end-systolic dimension of 40 mm or more, new atrial fibrillation, or pulmonary artery systolic pressure above 50 mmHg. Mitral valve repair is preferred over replacement for degenerative MR because of better outcomes and lower mortality. Secondary MR should be managed by first optimizing guideline-directed medical therapy for heart failure; MitraClip (COAPT trial) demonstrated benefit in patients with HFrEF and disproportionately severe MR despite maximal medical therapy, whereas the MITRA-FR trial found no benefit when MR was proportionate to LV dysfunction.
Mitral Stenosis
Percutaneous mitral balloon commissurotomy (PMBC) is preferred for pliable, non-calcified valves without significant MR or left atrial thrombus, using a Wilkins score of 8 or below to guide selection. Surgical repair or replacement is reserved for calcified or unfavorable valves and failed PMBC. Medical management includes rate control for atrial fibrillation (beta-blockers, digoxin), anticoagulation for AF, and diuretics for congestion.
Tricuspid Regurgitation
Medical management with diuretics and treatment of the underlying cause (left-sided heart failure, pulmonary hypertension) is the initial approach. Surgical repair at the time of left-sided valve surgery should be performed if TR is severe or the annulus is dilated (40 mm or more). Emerging transcatheter therapies include TriClip and EVOQUE.
Prosthetic Valve Considerations
Mechanical valves require lifelong warfarin anticoagulation, with INR targets varying by valve position. DOACs are contraindicated (the RE-ALIGN trial was halted due to harm). Bioprosthetic valves have a limited lifespan of 10 to 20 years, require anticoagulation for the first 3 to 6 months, then only antiplatelet therapy. Valve-in-valve TAVR is an emerging option for degenerated surgical bioprostheses. Endocarditis prophylaxis is recommended for prosthetic valves, prior endocarditis, and certain congenital conditions before dental procedures.
<image> A four-panel illustration showing the echocardiographic appearance of the four major valve lesions. Top-left: Severe aortic stenosis with heavily calcified leaflets and reduced opening in parasternal long-axis view, with continuous wave Doppler showing peak velocity >4 m/s. Top-right: Severe mitral regurgitation with color Doppler showing a large regurgitant jet filling the left atrium. Bottom-left: Severe aortic regurgitation with color flow Doppler showing a broad diastolic jet in the LVOT. Bottom-right: Mitral stenosis showing thickened leaflets with restricted opening and "hockey stick" appearance of the anterior leaflet. Each panel labeled with the view and severity criteria. </image>
<image> An anatomical illustration of the heart valves viewed from above (surgeon's view), showing all four valves in the open position. The aortic valve with three cusps, mitral valve with two leaflets and chordae tendineae, tricuspid valve with three leaflets, and pulmonic valve. Overlay indicators showing common pathology locations: calcification on aortic cusps, myxomatous degeneration of mitral posterior leaflet (P2 prolapse), and annular dilation of the tricuspid valve. Include the fibrous skeleton connecting the valves. Labeled with anatomical structures and clinical correlations. </image>
<image> A clinical decision algorithm for management of severe aortic stenosis. Start with "Severe AS Confirmed" branching into symptomatic vs asymptomatic. Symptomatic branch leads to surgical risk assessment (STS score/frailty), then SAVR vs TAVR decision based on age, risk, anatomy. Asymptomatic branch shows indications for intervention (EF<50%, exercise test positive, very severe, rapid progression) vs watchful waiting with serial echo. Include the landmark trials at each decision node (PARTNER series, Evolut). Clean flowchart with blue and green color scheme. </image>
Clinical Pearls
In aortic stenosis, the onset of symptoms marks a critical inflection point in prognosis -- once symptomatic, survival without intervention drops dramatically. TAVR is now an option across all surgical risk categories, and shared decision-making should weigh age, anatomy, comorbidities, and valve durability. Low-flow, low-gradient AS is a diagnostic trap -- dobutamine stress echocardiography or CT calcium scoring should always be considered when the gradient seems discordant with the clinical picture. Acute severe MR or AR can lead to rapid deterioration -- these are surgical emergencies. For secondary MR, guideline-directed medical therapy should always be optimized before considering intervention, and MitraClip benefits only selected patients meeting COAPT criteria with disproportionately severe MR. The timing of intervention in asymptomatic severe valve disease is shifting earlier, with growing evidence that "watchful waiting" may allow subclinical myocardial damage to develop. Mechanical valves require lifelong warfarin -- DOACs are contraindicated and dangerous in this setting. Bedside murmur assessment retains considerable value: a late-peaking, diminished systolic murmur with absent A2 suggests severe aortic stenosis even before echocardiography is performed.
References
- Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Valvular Heart Disease. Circulation. 2021.
- PARTNER 3 Trial: Mack MJ, et al. TAVR in Low-Risk Patients. NEJM. 2019.
- Evolut Low Risk Trial: Popma JJ, et al. NEJM. 2019.
- COAPT Trial: Stone GW, et al. Transcatheter Mitral-Valve Repair in Patients with Heart Failure. NEJM. 2018.
- MITRA-FR Trial: Obadia JF, et al. NEJM. 2018.
- Nishimura RA, et al. 2017 AHA/ACC Focused Update on VHD. Circulation. 2017.
