When should a Swan‑Ganz (pulmonary artery) catheter be placed intra‑operatively to monitor pulmonary vascular resistance in Tetralogy of Fallot patients?

Swan-Ganz Catheter for Intraoperative PVR Monitoring in Tetralogy of Fallot

Swan-Ganz catheterization is not routinely indicated for intraoperative monitoring during Tetralogy of Fallot surgery; current guidelines emphasize noninvasive echocardiographic and MRI assessment for hemodynamic evaluation, with invasive catheterization reserved for specific diagnostic scenarios when noninvasive data are inadequate.

Guideline-Based Indications for Catheterization

The ACC/AHA guidelines do not recommend routine intraoperative Swan-Ganz monitoring for TOF repair. Instead, catheterization is indicated in specific circumstances 1:

When Catheterization IS Indicated:

• When adequate hemodynamic data cannot be obtained noninvasively before planned surgical intervention 1
• To assess pulmonary vascular resistance when RV pressure exceeds 50% of systemic pressure or when RV dysfunction is present at lower pressures 1
• To evaluate branch pulmonary artery stenosis causing unbalanced pulmonary blood flow (>75% or <25% distribution) 1
• To define potentially treatable causes of unexplained RV or LV dysfunction, fluid retention, chest pain, or cyanosis in previously repaired patients 1

Preoperative vs. Intraoperative Timing:

The guidelines consistently frame catheterization as a preoperative diagnostic tool rather than an intraoperative monitoring modality 1. The emphasis is on obtaining complete hemodynamic assessment before surgery to guide surgical planning, not continuous intraoperative PVR monitoring.

Recommended Intraoperative Monitoring Strategy

Based on contemporary anesthesia guidelines for TOF patients 2:

Standard Intraoperative Goals (Without Swan-Ganz):

• Maintain RV function by optimizing preload, reducing afterload, and supporting contractility 2
• Minimize increases in PVR by avoiding hypoxia, hypercarbia, acidosis, hypothermia, and excessive positive pressure ventilation 2
• Prevent tachycardia to preserve diastolic filling time and coronary perfusion 2
• Maintain systemic vascular resistance to prevent right-to-left shunting if residual ASD/VSD exists 2

Preferred Monitoring Modalities:

• Comprehensive transthoracic echocardiography is the primary tool for assessing RVOT obstruction, pulmonary regurgitation, tricuspid regurgitation, RV pressure (via tricuspid regurgitant velocity), and residual VSD 3, 4
• Intraoperative transesophageal echocardiography provides real-time assessment of surgical repair adequacy and hemodynamics 2

Clinical Algorithm for Decision-Making

Scenario 1: Primary Complete Repair in Infancy

• No Swan-Ganz catheter indicated 3, 5
• Use standard ASA monitoring plus intraoperative TEE 2
• Preoperative cardiac MRI defines anatomy, ventricular function, and tissue characterization 3

Scenario 2: Complex Anatomy with Suspected Elevated PVR

• Preoperative cardiac catheterization (not intraoperative Swan-Ganz) to measure PA pressures and calculate PVR 1
• If RV pressure >50% systemic or RV dysfunction present, catheterization defines pulmonary vascular architecture and resistance before committing to repair 1
• Surgical approach modified based on catheterization findings 1

Scenario 3: Reintervention Surgery

• Preoperative catheterization indicated when noninvasive imaging cannot adequately define residual RVOT obstruction, branch PA stenosis, or residual shunts 1
• Intraoperative Swan-Ganz not routinely used; rely on TEE and direct PA pressure measurement if needed 2

Critical Pitfalls to Avoid

• Do not use Swan-Ganz catheter routinely for intraoperative monitoring in standard TOF repair; the risk-benefit ratio does not support routine use when noninvasive methods are adequate 1, 6
• Recognize that clinical examination alone underestimates pulmonary regurgitation severity; serial cardiac MRI is essential for accurate postoperative assessment 3
• Branch pulmonary artery stenosis may be missed on echocardiography; MRI or preoperative catheter angiography is required for complete assessment 3
• Inadequate preoperative assessment increases perioperative risk; ensure recent comprehensive echocardiography and knowledge of residual lesions before any intervention 2

Special Considerations for Complex Cases

For the rare palliated patient with TOF and systemic-to-pulmonary shunts, preoperative catheterization should assess pulmonary architecture, vascular pressure, and resistance because pulmonary artery distortion and pulmonary hypertension are frequent sequelae 1. Even in these complex scenarios, the catheterization is performed before surgery for diagnostic purposes, not as continuous intraoperative monitoring 1.

The contemporary approach prioritizes comprehensive preoperative hemodynamic assessment via catheterization when indicated, combined with intraoperative TEE, rather than routine Swan-Ganz monitoring 1, 2.