3.6 Valvular Heart Disease: Stenosis & Regurgitation

3.6 Valvular Heart Disease: Stenosis & Regurgitation

Valvular heart disease involves structural stenosis (failure of a valve to open fully, increasing pressure workload) or regurgitation/insufficiency (failure of a valve to close completely, causing blood backflow and volume overload). Understanding valvular hemodynamics, characteristic auscultatory murmurs, diagnostic criteria, and advanced interventional therapies (SAVR, TAVR, MitraClip) is vital for the AACN Cardiac Medicine Certification.

Aortic Valve Disorders

Aortic Stenosis (AS)

• Etiology: Age-related calcific degeneration (most common in adults >70 years), congenital bicuspid aortic valve (presents earlier, ages 40–60), or rheumatic heart disease.
• Pathophysiology: Chronic obstruction to LV outflow forces the left ventricle to generate massive systolic pressures, leading to severe concentric LV hypertrophy. Hypertrophy reduces LV compliance, raising end-diastolic pressure and impairing coronary perfusion.
• Classic Clinical Triad ("SAD"):
  1. S - Syncope: Exertional syncope due to fixed cardiac output unable to meet peripheral exercise vasodilation.
  2. A - Angina: Myocardial ischemia from extreme muscle mass demand exceeding coronary supply.
  3. D - Dyspnea / Heart Failure: Exertional dyspnea progressing to overt pulmonary edema.
• Auscultation & Peripheral Exam:
  • Murmur: Harsh crescendo-decrescendo systolic ejection murmur, best heard at the right 2nd intercostal space, radiating to the carotid arteries.
  • Pulsus Parvus et Tardus: Carotid pulse is weak (parvus) and delayed (tardus).
  • S2 Changes: Single S2 or paradoxically split S2 (A2 delayed behind P2).
• Diagnostic Thresholds for Severe AS:
  • Aortic Valve Area (AVA): < 1.0 cm² (or AVA index < 0.6 cm²/m²).
  • Mean Pressure Gradient: > 40 mmHg.
  • Peak Jet Velocity: > 4.0 m/s.
• Nursing Priorities & Interventions:
  • Avoid Hypotension & Preload Depletion: Patients with severe AS are strictly preload-dependent. Vasodilators (ACEi, nitrates) and vigorous diuresis must be used with extreme caution to prevent circulatory collapse.
  • Intervention Timing: Indicated for any symptomatic severe AS, or asymptomatic severe AS with LVEF < 50%. Options include Surgical Aortic Valve Replacement (SAVR) or Transcatheter Aortic Valve Replacement (TAVR).

Aortic Regurgitation (AR)

• Etiology: Leaflet damage (infective endocarditis, rheumatic fever) or aortic root dilation (aortic dissection, Marfan syndrome, severe HTN).
• Pathophysiology: Blood regurgitates from the aorta into the LV during diastole. The LV undergoes massive eccentric hypertrophy and dilation to accommodate both normal atrial inflow and regurgitant volume ("cor bovinum" / massive heart).
• Acute vs. Chronic AR:
  • Acute AR: Normal-sized, non-compliant LV is overwhelmed by sudden volume. Presents as catastrophic cardiogenic shock and pulmonary edema. Immediate surgical emergency!
  • Chronic AR: LV adaptively dilates over decades, remaining asymptomatic until severe LV dysfunction develops.
• Physical Exam Hallmarks:
  • Widened Pulse Pressure: High systolic BP with extremely low diastolic BP (e.g., 160/45 mmHg).
  • Corrigan's / Water-Hammer Pulse: Bounding arterial pulse with rapid stroke rise and sudden collapse.
  • Auscultation: High-pitched, decrescendo early diastolic murmur at the left sternal border. Austin Flint Murmur: Low-pitched mid-diastolic rumble at the apex, caused by the regurgitant aortic jet striking the anterior mitral leaflet.
• Management: Surgical aortic valve replacement is the definitive therapy. The 2020 ACC/AHA valvular guideline dropped the older "vasodilator as a bridge to surgery" recommendation — nifedipine to delay surgery is no longer current practice. Medical therapy is now limited to treating hypertension (systolic > 140 mmHg) in asymptomatic disease, and guideline-directed therapy with an ACE inhibitor/ARB or sacubitril-valsartan in symptomatic severe AR with LV dysfunction when surgical risk is prohibitive. Transcatheter therapy for pure native AR remains off-label in general practice (the 2020 guideline gives it a Class 3), though a dedicated device received FDA approval in March 2026 for high-surgical-risk symptomatic severe AR.

Mitral Valve Disorders

Mitral Stenosis (MS)

• Etiology: Overwhelmingly caused by Rheumatic Heart Disease (post-streptococcal autoimmune cross-reactivity) resulting in commissural fusion and leaflet thickening ("fish-mouth" valve orifice).
• Pathophysiology: Obstruction of blood flow from the left atrium into the left ventricle during diastole leads to elevated Left Atrial (LA) pressures, progressive LA enlargement, and backward transmission into the pulmonary vasculature, causing secondary pulmonary arterial hypertension and right ventricular failure.
• Complications:
  • Atrial Fibrillation: Marked LA stretch triggers AF in up to 50% of patients. Loss of atrial kick combined with rapid heart rate drastically impairs diastolic LV filling, causing sudden hemodynamic collapse.
  • Systemic Thromboembolism: LA stasis combined with AF creates an extremely high risk for mural thrombus formation and stroke.
• Auscultation: Loud S1, followed by a high-pitched Opening Snap (OS) in early diastole, followed by a low-pitched mid-diastolic rumble best heard at the apex in the left lateral decubitus position with the bell.
• Diagnostic Thresholds: Severe MS is defined as Mitral Valve Area (MVA) ≤ 1.5 cm².
• Management: Rate control (beta-blockers, non-DHP CCBs) to prolong diastolic filling time. Mandatory Anticoagulation (Warfarin) for MS with Afib. Interventions include Percutaneous Transvenous Mitral Commissurotomy (PTMC / Balloon Valvuloplasty) or surgical replacement.

Mitral Regurgitation (MR)

• Etiology: Primary/Organic (Mitral Valve Prolapse [MVP], chordae tendineae rupture, infective endocarditis) or Secondary/Functional (LV dilation stretching the mitral annulus in dilated or ischemic cardiomyopathy).
• Acute MR (Post-MI Papillary Muscle Rupture):
  • Occurs 2 to 7 days post-MI (most commonly inferior MI affecting the posteromedial papillary muscle, which has a single blood supply from the Posterior Descending Artery).
  • Manifests as abrupt, catastrophic pulmonary edema, hypotension, hyperdynamic apical impulse, and a soft holosystolic murmur.
  • Emergency Management: Intra-aortic balloon pump (IABP) or Impella support to reduce afterload and regurgitant volume, alongside immediate emergency surgical valve repair/replacement.
• Chronic MR:
  • Asymptomatic for years due to progressive LA and LV enlargement. Leads to eventual LV systolic failure.
  • Auscultation: Blowing holosystolic (pansystolic) murmur at the cardiac apex radiating into the left axilla.
• Interventions: Surgical Mitral Valve Repair (preferred over replacement). For high surgical risk patients, Transcatheter Edge-to-Edge Repair (TEER / MitraClip) clips the anterior and posterior leaflets together to reduce regurgitation.

Tricuspid & Pulmonic Valve Disorders

Tricuspid Regurgitation (TR)

• Etiology: Most commonly functional/secondary to Right Ventricular dilation and pulmonary hypertension; primary causes include infective endocarditis (in intravenous drug users) and pacemaker lead damage.
• Physical Exam: Prominent 'v' wave in jugular venous pulsations, holosystolic murmur at the lower left sternal border that increases with inspiration (Carvallo's sign), hepatomegaly with pulsatile liver, ascites, and peripheral edema.

Pulmonic Valve Disorders

• Pulmonic Stenosis (PS): Almost exclusively congenital (Tetralogy of Fallot, Noonan syndrome). Auscultation reveals a systolic ejection murmur at the left upper sternal border with an ejection click.
• Pulmonic Regurgitation (PR): Most commonly secondary to severe pulmonary arterial hypertension, producing a high-pitched early diastolic decrescendo murmur (Graham Steell murmur).

Prosthetic Valve Selection & Nursing Management

When native valve repair is unfeasible, valve replacement is performed using either mechanical or bioprosthetic tissue valves.

Target INR Ranges for Mechanical Valves

• Mechanical Aortic Valve: Target INR 2.0 – 3.0.
• Mechanical Mitral Valve (or Aortic with risk factors): Target INR 2.5 – 3.5 (higher thromboembolic risk due to lower velocity flow across the mitral position).

Post-Procedure Nursing Priorities (TAVR & MitraClip)

1. Vascular Access Monitoring: Transfemoral access sites require frequent vascular checks to detect hematoma formation, retroperitoneal hemorrhage (sudden flank pain, hypotension, tachycardia), or pseudoaneurysm.
2. Conduction Disturbances (Post-TAVR): The aortic valve lies in close anatomical proximity to the AV node and bundle of His. Balloon expansion can cause new high-grade AV block or LBBB, requiring continuous cardiac monitoring and frequent permanent pacemaker placement.
3. Stroke Monitoring: Thromboembolic debris liberated during valve deployment requires immediate post-procedure neurological assessments (NIHSS).