Valve Replacement Surgery for Severe Aortic Stenosis

Aortic stenosis (AS) is the most common valvular disease in adults, often progressing to symptomatic heart failure if untreated. In India, the prevalence is rising due to improved life expectancy and better diagnostic capabilities. When medical therapy fails to relieve symptoms or prevent progression, aortic valve replacement (AVR) becomes the definitive treatment. This article explores the surgical techniques available in India, the peri‑operative risk profile, and evidence‑based postoperative management to optimize outcomes.

1. Indications for AVR in Severe Aortic Stenosis

• Symptomatic severe AS (NYHA class II–IV)
• Left ventricular ejection fraction < 50% despite optimal medical therapy
• Paradoxical low output (dyspnea, syncope) or rapid progression of gradient
• Concomitant indications such as coronary artery disease requiring CABG or infective endocarditis
• High surgical risk patients may be considered for transcatheter options (TAVI)

2. Surgical Techniques Available in India

The choice of AVR technique depends on patient factors, surgeon expertise, and institutional resources. The most common methods are:

2.1 Conventional Surgical AVR (SAVR)

• Mechanical prosthesis (e.g., St. Jude, Carbomedics) – durable but requires lifelong anticoagulation.
• Bioprosthetic valve (e.g., Medtronic Mosaic, Edwards Sapien) – lower anticoagulation requirement but limited durability.
• Procedure performed via median sternotomy with cardiopulmonary bypass (CPB) and aortic cross‑clamp.
• Intraoperative transesophageal echocardiography (TEE) confirms correct sizing and positioning.

2.2 Minimally Invasive AVR (Mini‑AVR)

• Right anterior thoracotomy or mini‑sternotomy (≤ 5–6 cm) reduces surgical trauma.
• Use of small aortic clamp and rapid‑sequence CPB reduces cross‑clamp time.
• Postoperative pain is lower and LOS (length of stay) averages 4–5 days.

2.3 Transcatheter Aortic Valve Implantation (TAVI)

• Percutaneously delivered through femoral or transapical access.
• Indicated for high‑risk or inoperable patients; increasingly used in intermediate risk.
• Valve options: Edwards Sapien 3, Medtronic CoreValve Evolut R.
• Post‑deployment TEE and fluoroscopy confirm valve position; residual gradient < 20 mmHg acceptable.

3. Pre‑operative Evaluation and Testing in India

• Echocardiography (Transthoracic & TEE) – to quantify gradient, valve area, LV function.
• CT Angiography – evaluates annulus size, coronary anatomy, vascular access.
• Cardiac MRI – if LV hypertrophy or fibrosis assessment needed.
• Laboratory tests: CBC, CMP, coagulation profile, renal function (CrCl), lipid panel.
• Pre‑operative cardiac catheterization if coronary artery disease suspected.

4. Peri‑operative Risk Factors and Management

The operative risk is influenced by age, frailty, renal function, COPD, and concomitant procedures. The Society of Thoracic Surgeons (STS) risk score is commonly used in India to estimate mortality and morbidity.

4.1 Intra‑operative Strategies

• CPB Management: Maintain normothermia (35–37°C), hematocrit 25–30%, and adequate flow.
• Cross‑clamp time: Aim < 90 minutes; use rapid deployment prostheses when possible.
• Hemostasis: Employ meticulous technique; use fibrin sealants and topical agents.
• TEE Guidance: Real‑time assessment of prosthesis size, position, paravalvular leak.

4.2 Post‑operative Monitoring

• ICU care: Hemodynamic monitoring, inotropes if LV dysfunction.
• Serial TTE on days 1, 3, and at discharge to assess gradient, ejection fraction.
• Early mobilization (within 24 h) reduces pulmonary complications.
• Monitor for conduction disturbances; consider temporary pacing if complete heart block.

4.3 Medication Regimen Post‑AVR

• Anticoagulation (Mechanical valve): Warfarin with INR 2.5–3.5; transition to NOACs not yet approved for mechanical valves in India.
• Antiplatelet therapy (Bioprosthetic valve): Aspirin 75–100 mg daily; clopidogrel 75 mg if dual therapy indicated.
• Heart failure drugs: ACE inhibitors or ARBs, beta‑blockers (metoprolol 25–100 mg), diuretics as needed.
• Statins: Atorvastatin 20–40 mg to reduce atherosclerotic progression.
• Post‑operative pain control: Opioid sparing regimen with acetaminophen, NSAIDs if renal function permits.

5. Common Post‑operative Complications and Mitigation

• Paravalvular leak (PVL): Ensure correct annulus sizing; use intra‑operative TEE to detect leaks.
• Bleeding: Maintain adequate platelet function; consider tranexamic acid 10 mg/kg IV at start of CPB.
• Renal dysfunction: Avoid nephrotoxic agents; maintain urine output > 0.5 mL/kg/h.
• Infection: Strict aseptic technique; prophylactic antibiotics (cefazolin 2 g IV) pre‑op and for 24 h post‑op.
• Arrhythmias: Monitor ECG continuously; treat with magnesium sulfate for torsades or amiodarone for atrial fibrillation.

6. Long‑Term Follow‑Up and Outcomes in Indian Centers

• Annual echocardiography to monitor prosthesis function.
• Lifestyle modifications: smoking cessation, diet rich in fruits/vegetables, regular exercise (30 min brisk walking).
• Vaccinations: influenza and pneumococcal to reduce respiratory infections.
• Patient education on anticoagulation monitoring and symptom reporting.

7. Conclusion

Aortic valve replacement remains the cornerstone of therapy for severe aortic stenosis. In India, a spectrum of surgical options—from conventional SAVR to minimally invasive techniques and TAVI—offers tailored treatment for diverse patient populations. Meticulous pre‑operative evaluation, precise surgical execution, and comprehensive postoperative care—including guideline‑directed pharmacotherapy—are essential to minimize complications and improve survival. Continuous data collection through national registries will further refine risk stratification and optimize outcomes for Indian patients undergoing AVR.

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