Cardiac complications

Cardiac Risk Assessment - Sizing Up The Heart

• Goal: Identify patients at risk for Major Adverse Cardiac Events (MACE).
• Functional Capacity: Assessed in Metabolic Equivalents ($METs$).
  • Poor: <4 METs (e.g., slow walking, self-care).
  • Excellent: >10 METs (e.g., strenuous sports).
• Revised Cardiac Risk Index (RCRI): 1 point per risk factor.
  • High-risk surgery (e.g., vascular)
  • History of ischemic heart disease
  • History of CHF
  • History of CVA/TIA
  • Pre-op insulin use
  • Pre-op creatinine >2.0 mg/dL

⭐ In patients with elevated risk (RCRI ≥1) but good functional capacity (≥4 METs), it is reasonable to proceed with the planned surgery without further cardiac testing.

Perioperative MI - The Silent Killer

• Pathophysiology: Surgical stress → catecholamine surge → tachycardia & hypertension → ↑O₂ demand and ↓diastolic filling time → myocardial ischemia.
• Clinical Presentation: Often silent (no chest pain) due to anesthesia/analgesia. May present as hypotension, arrhythmia, delirium, or oliguria.
• Diagnosis:
  • ECG: New ST-segment changes, LBBB, or pathologic Q waves.
  • Biomarkers: Rise and/or fall of troponins with at least one value >99th percentile.
• Prevention: Preoperative risk stratification (RCRI score), β-blockers in high-risk patients, and statin therapy.

⭐ Most perioperative MIs are NSTEMIs and occur within 48-72 hours post-op, often triggered by physiologic stressors like pain and anemia.

Post-Op Heart Failure - The Pump Sputters

• Etiology: Often due to fluid overload from IV fluids, stress-induced myocardial ischemia/infarction, or exacerbation of underlying chronic heart failure (especially diastolic dysfunction).

• Diagnosis: Look for dyspnea, bilateral crackles, JVD, and a new S3 gallop.

  • Labs: ↑ BNP (B-type Natriuretic Peptide > 400 pg/mL).
  • Imaging: Chest X-ray shows pulmonary edema; echocardiogram is the definitive diagnostic tool.

• Management:

  • 📌 LMNOP: Lasix (furosemide) for diuresis, Morphine for venodilation/anxiolysis, Nitrates for vasodilation, Oxygen for hypoxia, Position (sit upright).

⭐ The most common cause of post-operative heart failure is iatrogenic fluid overload, particularly in elderly patients with unrecognized pre-existing diastolic dysfunction.

Post-Op Arrhythmias - The Heart's Hiccups

• Commonly occurs 2-4 days post-op, with Atrial Fibrillation (AFib) being the most frequent type.

• Key Triggers:

  • Electrolyte imbalance (↓K⁺, ↓Mg²⁺)
  • Hypoxemia, anemia, pain
  • Volume overload, inflammation
  • Underlying cardiac disease

• Management Steps:

  • 1st: ABCs, EKG, check labs (electrolytes, troponins).
  • Stable AFib: Rate control is key. Use β-blockers (metoprolol) or CCBs (diltiazem).
  • Unstable (hypotension, shock): Immediate synchronized cardioversion.

⭐ High-Yield: New-onset post-op AFib is a major risk factor for future stroke and mortality. Consider prophylactic β-blockers in high-risk patients undergoing major surgery.

High‑Yield Points - ⚡ Biggest Takeaways

• Perioperative MI is the leading cause of death after noncardiac surgery, often presenting silently within 48 hours.
• Use the Revised Cardiac Risk Index (RCRI) to stratify patients; key risks include IHD, CHF, CVA, DM on insulin, and Cr >2.
• Prophylactic beta-blockers and statins are crucial in high-risk patients to reduce cardiac events.
• Postoperative atrial fibrillation is common; prioritize rate control over rhythm control initially.
• New-onset pulmonary edema suggests either fluid overload or underlying cardiac dysfunction.