What is the procedure for VSD (Ventricular Septal Defect) closure under CPB (Cardiopulmonary Bypass) with pressure-controlled ventilation?

Procedure for VSD Closure Under CPB with Pressure-Controlled Ventilation

VSD closure under cardiopulmonary bypass (CPB) with pressure-controlled ventilation should be performed by surgeons with specialized training and expertise in congenital heart disease to ensure optimal outcomes and minimize complications. 1

Patient Selection and Preoperative Assessment

Indications for VSD Closure

• Hemodynamically significant VSD with Qp:Qs ≥1.5:1 and evidence of left ventricular volume overload 1
• PA systolic pressure less than 50% systemic and pulmonary vascular resistance less than one-third systemic 1
• History of infective endocarditis caused by VSD 1
• VSD with worsening aortic regurgitation 1

Contraindications

• Severe irreversible pulmonary arterial hypertension (PAH) with PA systolic pressure greater than two-thirds systemic 1
• Pulmonary vascular resistance greater than two-thirds systemic 1
• Net right-to-left shunt (Eisenmenger syndrome) 1

Preoperative Evaluation

• Echocardiography to determine:
  • Size and location of VSD (perimembranous, muscular, inlet, or apical)
  • Presence of additional VSDs
  • Degree of left-to-right shunting (Qp:Qs ratio)
  • Pulmonary artery pressure
  • Associated lesions (aortic valve prolapse, AR)
• Cardiac catheterization when:
  • Pulmonary hypertension is suspected
  • Noninvasive data are inconclusive
  • Operability assessment is needed in patients with VSD and PAH 1

Surgical Procedure

Anesthesia and Ventilation Setup

1. Induction of anesthesia with standard cardiac anesthesia protocol
2. Endotracheal intubation
3. Pressure-controlled ventilation settings:
   • Set appropriate peak inspiratory pressure
   • Set respiratory rate to maintain normal PaCO2
   • Set PEEP (positive end-expiratory pressure) - PEEP during CPB should be considered for lung protection 1
   • Set FiO2 to maintain adequate oxygenation
   • Consider avoiding hyperoxia as it may lead to alveolar collapse and oxygen radical generation 1

Surgical Approach Options

1. Conventional approach with CPB:

   • Median sternotomy
   • Establishment of CPB with aortic and bicaval cannulation
   • Moderate hypothermia
   • Aortic cross-clamping and cardioplegic arrest
   • Right atriotomy or right ventriculotomy for access to VSD
   • VSD closure with patch (typically Dacron or Gore-Tex) 1
   • Careful inspection for additional VSDs using TEE 1
   • Weaning from CPB
   • Decannulation and closure

2. Perventricular device closure approach (hybrid approach):

   • Minimally invasive subxiphoid incision or small sternotomy 2, 3
   • No CPB required
   • Transesophageal echocardiography (TEE) guidance
   • Purse-string suture on right ventricular free wall
   • Puncture of RV free wall with trocar
   • Guidewire insertion across VSD into left ventricle
   • Device delivery sheath placement
   • Device deployment across VSD
   • Device release after confirming proper position
   • Closure of RV puncture site 4

Ventilation Management During CPB

• Options during CPB:
  1. No mechanical ventilation (lungs deflated)
  2. Continuous positive end-expiratory pressure (PEEP)
  3. Low minute volume ventilation with PEEP 1
• Ventilation during CPB may be considered for lung protection 1
• Avoid hyperoxia as it's not recommended for lung protection during CPB 1

Post-CPB Management

1. Resume pressure-controlled ventilation with appropriate settings
2. Perform lung recruitment maneuvers if needed
3. Maintain adequate PEEP to prevent atelectasis
4. TEE assessment of VSD closure and ventricular function
5. Hemodynamic optimization
6. Closure of surgical incision

Postoperative Care

Immediate Postoperative Management

• Continue pressure-controlled ventilation in ICU
• Aim for early extubation when criteria are met
• Monitor for:
  • Residual VSD shunts
  • Arrhythmias (particularly heart blocks)
  • Pulmonary hypertensive crisis
  • Bleeding
  • Low cardiac output syndrome

Follow-up

• Adults with VSD with residual heart failure, shunts, PAH, AR, or RVOT/LVOT obstruction should be seen annually at an ACHD center 1
• Adults with small residual VSD should be seen every 3-5 years 1
• ECG monitoring for development of heart block, particularly in patients who developed bifascicular or transient trifascicular block after VSD closure 1

Special Considerations and Potential Complications

Potential Complications

• Residual VSD
• Complete heart block requiring pacemaker
• Ventricular dysfunction
• Pulmonary hypertensive crisis
• Aortic regurgitation
• Tricuspid regurgitation
• Infective endocarditis

Pitfalls to Avoid

• Failure to identify additional VSDs
• Mistaking VSD jet for TR jet in patients with normal pulmonary pressure 1
• Failure to recognize RV outflow obstruction associated with VSD 1
• Inappropriate patient selection (severe irreversible PAH)
• Inadequate lung protection strategies during CPB

Alternative Approaches

• Percutaneous device closure (limited by vascular access in pediatric patients)
• Hybrid perventricular approach without CPB for selected cases 2, 3, 4
• Primary closure for very small VSDs (rare) 1

The choice of surgical approach should be based on VSD location, size, patient characteristics, and institutional expertise, with the primary goal of improving morbidity, mortality, and quality of life outcomes.