What EKG changes are associated with rhabdomyolysis (rhabdomyolysis)?

ECG Changes in Rhabdomyolysis

The most significant ECG changes associated with rhabdomyolysis are those related to hyperkalemia, including peaked T waves, widened QRS complexes, and potentially life-threatening arrhythmias.

Pathophysiology of ECG Changes in Rhabdomyolysis

Rhabdomyolysis causes muscle breakdown with release of intracellular contents into the circulation, leading to several electrolyte abnormalities that manifest on ECG:

Primary ECG Findings

1. Hyperkalemia-related changes 1, 2:

   • Tall, peaked T waves (early finding)
   • Prolonged PR interval
   • Flattened or absent P waves
   • Widened QRS complexes
   • Sine wave pattern (in severe cases)
   • Ventricular fibrillation or asystole (terminal event)

2. Metabolic acidosis effects:

   • Nonspecific ST-segment and T-wave changes
   • Enhanced hyperkalemic ECG changes

3. Early hypocalcemia manifestations:

   • Prolonged QT interval
   • ST-segment changes

4. Late hypercalcemia findings 2:

   • Shortened QT interval
   • Osborn waves (J waves)

Clinical Significance and Monitoring

The American Heart Association recommends continuous electrocardiographic monitoring for patients with severe electrolyte abnormalities, such as those seen in rhabdomyolysis with acute renal failure 3. This is particularly important because:

• ECG changes may precede clinical symptoms
• Hyperkalemia can rapidly progress to life-threatening arrhythmias
• Early detection allows prompt intervention

Risk Stratification

Patients with rhabdomyolysis requiring ECG monitoring include:

• Those with CK levels >10,000 U/L
• Patients with acute kidney injury
• Cases with documented electrolyte abnormalities
• Patients with pre-existing cardiac disease
• Individuals with prolonged immobilization or crush injuries

Management Considerations

When ECG changes are detected in rhabdomyolysis:

1. Immediate intervention for hyperkalemia 4:

   • Calcium gluconate (10 mL of 10% solution IV) for cardiac membrane stabilization
   • Insulin (10 units regular) with glucose (25-50g) to shift potassium intracellularly
   • Sodium bicarbonate (50 mEq IV) if acidotic
   • Consider emergent dialysis for severe, refractory hyperkalemia

2. Aggressive fluid resuscitation:

   • Maintain urine output >300 mL/hour to prevent myoglobin-induced renal damage
   • Monitor for fluid overload in patients with cardiac or renal compromise

3. Serial ECG monitoring:

   • Repeat ECGs to assess response to treatment
   • Continue monitoring until electrolyte abnormalities resolve

Special Considerations

• Dialysis patients: Rhabdomyolysis in patients already on dialysis requires special attention as they are at higher risk for cardiovascular complications 5
• Pre-existing cardiac disease: Patients with underlying cardiac conditions may show exaggerated ECG changes and require more aggressive management
• Medication effects: Some medications used to treat rhabdomyolysis may themselves affect the ECG

Pitfalls to Avoid

1. Misattribution of ECG changes: Not all ECG abnormalities in rhabdomyolysis patients are due to electrolyte disturbances; consider concurrent cardiac pathology
2. Delayed recognition: Subtle early hyperkalemic changes may be missed if not specifically sought
3. Inadequate monitoring: Intermittent ECGs may miss rapidly evolving changes
4. Overlooking other electrolyte abnormalities: While hyperkalemia is most common, hypocalcemia, hyperphosphatemia, and acidosis also contribute to ECG changes

By promptly recognizing and addressing ECG changes in rhabdomyolysis, clinicians can prevent progression to life-threatening arrhythmias and improve patient outcomes.