Anesthesia for Coronary Artery Disease

Anesthesia for CAD: Pathophys & Risk - Heart Under Siege

• Pathophysiology: Atherosclerosis → coronary stenosis → ↓ Myocardial $O_2$ Supply.
  • Ischemia: Myocardial $O_2$ Demand ($MVO_2$) > $O_2$ Supply.
  • $MVO_2$ determinants: Heart Rate, Contractility, Wall Tension (Preload, Afterload).
  • $O_2$ Supply determinants: Coronary Blood Flow (CBF), Arterial $O_2$ Content.
  • CBF critical factor: CPP (Aortic DBP - LVEDP).
• Perioperative Cardiac Risk:
  • High-risk: Recent MI, unstable angina, decompensated HF.
  • Risk Scores: e.g., RCRI, etc.
  • Functional Capacity: < 4 METs = poor reserve.
  • Tests: ECG, Stress tests, Echo, Troponin.

⭐ Most perioperative MIs are silent, non-Q wave, and occur within 48-72 hours postoperatively.

Anesthesia for CAD: PreOp Prep - Tuning The Engine

• Goal: ↓ Myocardial O₂ demand, ↑ O₂ supply; stabilize plaques.
• Medication Review & Optimization:
  • Continue: β-blockers (target HR 55-70 bpm), Statins.
  • Aspirin: Usually continue; weigh bleed vs. thrombotic risk.
  • P2Y12 inhibitors (e.g., Clopidogrel): Stop 5-7 days pre-op (consult team).
  • ACEi/ARBs, Diuretics: Hold on Day Of Surgery (DOS).
• Comorbidity Control:
  • HTN: Target BP < 140/90 mmHg.
  • DM: Target HbA1c < 7%.
  • Smoking: Cessation > 4 weeks.
• Anxiolysis: Premedicate if significant anxiety.

⭐ Continue β-blockers if already on them. Do NOT initiate acutely in naive patients for intermediate/low-risk surgery without specific ischemic indications.

Anesthesia for CAD: IntraOp Care - Navigating The Maze

• Core Goal: Balance Myocardial O₂ Supply (HR, rhythm, CaO₂, CPP: $DBP - LVEDP$) & Demand (HR, contractility, wall tension).
• Monitoring:
  • Standard + 5-lead ECG (II, V₅ for ischemia).
  • Invasive BP (A-line) for CPP.
  • TEE/PA cath for high-risk LV dysfunction.
• Anesthesia:
  • Induction: Smooth. Opioids (fentanyl), etomidate. Propofol with caution (↓BP).
  • Maintenance: Volatiles (Iso/Sevo > Des). Opioid-based.
  • NMB: Vecuronium, Rocuronium. Avoid pancuronium.
• Hemodynamic Targets (📌 HOBBS):
  • HR: 50-70 bpm (β-blockers: esmolol).
  • O₂ Sat: >95%.
  • BP: Within 20% baseline. Treat promptly.
    • Hypotension: Phenylephrine.
    • Hypertension: NTG, esmolol.
  • Balance: Judicious fluids, glucose control.
  • ST-segment: Monitor, treat ischemia.
• Regional: TEA beneficial (analgesia, sympatholysis), monitor BP.
• Extubation: Smooth, avoid sympathetic surge (e.g. lidocaine).

⭐ Perioperative beta-blockade is crucial in CAD patients to reduce myocardial ischemia and mortality.

Anesthesia for CAD: PostOp & Complications - After The Battle

• Pain Management: Reduces stress & MVO2.
  • Multimodal: Opioids, NSAIDs (cautious), paracetamol.
  • Thoracic Epidural (TEA): Excellent analgesia; monitor hypotension, hematoma.
• Major Complications & Management:
  • Myocardial Ischemia/Infarction (MI): Peak risk 24-72h. Dx: ECG, ↑Troponins. Rx: O2, nitrates, β-blockers.
  • Arrhythmias: Atrial Fibrillation (AF) common (20-40%). Rx: Rate/rhythm control (β-blockers, amiodarone), anticoagulation.
  • Low Cardiac Output Syndrome (LCOS): Optimize hemodynamics. Inotropes, vasopressors, IABP.
  • Hypertension: Aggressive control (GTN, labetalol) for graft safety & ↓MVO2.
• Monitoring: Continuous ECG (ST-segment), invasive BP, serial cardiac biomarkers.

⭐ Post-operative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery (20-40%), increasing stroke risk and mortality anagement focuses on rate/rhythm control and anticoagulation if persistent beyond 48 hours or in high-risk patients

High‑Yield Points - ⚡ Biggest Takeaways

• Core goal: Maintain myocardial oxygen supply-demand balance; avoid tachycardia, hypotension, and significant hypertension.
• Continue perioperative beta-blockers if already prescribed; use IV nitroglycerin for acute ischemia.
• ECG leads II and V5 are crucial for intraoperative ischemia monitoring.
• Volatile anesthetics provide dose-dependent cardioprotection.
• Effective postoperative pain control is vital to prevent stress-induced ischemia.
• TEE is invaluable for high-risk patients to detect new regional wall motion abnormalities.