How to manage hypotension in a patient with repaired Tetralogy of Fallot?

Management of Hypotension in Patients with Repaired Tetralogy of Fallot

In patients with repaired Tetralogy of Fallot who develop hypotension, norepinephrine is the first-line vasopressor of choice to increase systemic vascular resistance and reduce right-to-left shunting, with a target systolic blood pressure appropriate for age. 1

Initial Assessment and Hemodynamic Considerations

When managing hypotension in patients with repaired Tetralogy of Fallot (ToF), it's crucial to understand the unique hemodynamic challenges these patients face:

• Right ventricular (RV) dysfunction: Most common long-term complication after ToF repair, typically due to pulmonary regurgitation, RV outflow tract obstruction, or both 2
• Elevated central venous pressure (CVP): Can mask the true severity of hypotension 3
• Pulmonary regurgitation: Present in most repaired ToF patients, contributing to RV dilation and dysfunction 2
• Residual lesions: Including RVOT obstruction, branch pulmonary artery stenosis, ventricular septal defects, or aortic regurgitation 2

Key Diagnostic Steps

1. Echocardiography: Immediately assess for:

   • Severity of pulmonary regurgitation
   • RV size and function
   • Residual RVOT obstruction
   • Tricuspid regurgitation
   • Residual VSDs
   • Aortic regurgitation 2

2. ECG monitoring: Evaluate for arrhythmias (atrial or ventricular), which are common in repaired ToF and can precipitate hypotension 2

3. Cardiac MRI (if stable enough): Gold standard for assessing RV volume and function 2

Treatment Algorithm

1. Immediate Management

• Vasopressor therapy: Start norepinephrine at 0.05-2 mcg/kg/min, titrated to maintain adequate blood pressure 1, 4

  • Increases systemic vascular resistance
  • Reduces right-to-left shunting
  • Improves tissue perfusion

• Positioning: Consider knee-chest position to increase systemic vascular resistance 1

• Oxygen supplementation: Provide supplemental oxygen at 6-8 L/min 1

2. Addressing Specific Causes

Based on echocardiographic findings, target the underlying cause:

A. If RV Dysfunction with Pulmonary Regurgitation:

• Optimize preload (avoid excessive fluid administration)
• Continue vasopressor support
• Consider inotropic support if evidence of RV failure
• Urgent consultation with ACHD specialist for possible pulmonary valve replacement if severe 2

B. If RVOT Obstruction:

• Avoid beta-blockers which can worsen obstruction
• Consider ketamine (1-2 mg/kg IV) for infundibular spasm 1
• Urgent consultation for possible catheter intervention or surgical relief of obstruction 2

C. If Arrhythmia-Related:

• Treat underlying arrhythmia (common in repaired ToF)
• Consider cardioversion for unstable tachyarrhythmias
• Temporary pacing for bradyarrhythmias 2

D. If Low Systemic Vascular Resistance:

• Continue norepinephrine
• Consider adding phenylephrine if needed 1
• Evaluate for sepsis or other causes of vasodilation

3. Monitoring and Ongoing Management

• Continuous hemodynamic monitoring: Be aware that elevated CVP may mask the true severity of hypotension 3
• Serial echocardiography: To assess response to treatment
• Avoid volume overload: Can worsen RV dysfunction and right-to-left shunting 1
• Monitor for acidosis: Can worsen pulmonary vasoconstriction 1

Special Considerations

• Pulmonary valve replacement: Consider urgent evaluation if severe pulmonary regurgitation with RV dysfunction is contributing to hemodynamic instability 2

• Catheter intervention: May be needed for residual lesions such as branch pulmonary artery stenosis or residual VSD 2

• Beware of masked hypotension: Elevated CVP in these patients can artificially increase mean arterial pressure, concealing the true severity of hypotension 3

Pitfalls to Avoid

• Excessive fluid administration: Can worsen RV dysfunction and increase right-to-left shunting 1
• Beta-blockers: May exacerbate RVOT obstruction
• Delayed recognition of arrhythmias: Common in repaired ToF and can precipitate hemodynamic compromise 2
• Overlooking residual lesions: Cardiomegaly on chest X-ray should prompt search for residual hemodynamic lesions 2

Remember that all patients with repaired ToF should have regular follow-up with a cardiologist who has expertise in adult congenital heart disease, with at least annual evaluations 2.