What is the management of patients with shunt-dependent circulation and dual pulmonary circulation?

Management of Shunt-Dependent Circulation with Dual Pulmonary Circulation

The management of patients with shunt-dependent circulation and dual pulmonary circulation requires careful anticoagulation, close monitoring for shunt thrombosis, and strategic planning for subsequent palliative or corrective surgeries to optimize outcomes and reduce mortality. 1

Understanding Shunt-Dependent Circulation with Dual Pulmonary Circulation

Shunt-dependent circulation refers to congenital heart conditions where pulmonary blood flow depends on an artificial connection (shunt) between the systemic and pulmonary circulation. Dual pulmonary circulation occurs when there are two sources of pulmonary blood flow:

1. The surgically created shunt (e.g., modified Blalock-Taussig shunt)
2. Native pulmonary blood flow (through patent pulmonary valve or collaterals)

This condition is typically seen in:

• Single ventricle physiology (tricuspid atresia, hypoplastic left/right heart)
• Complex congenital heart defects with pulmonary stenosis or atresia
• Patients awaiting staged palliation toward Fontan circulation

Acute Management of Shunt-Dependent Patients

Recognizing and Managing Shunt Thrombosis

Shunt thrombosis is life-threatening and requires immediate intervention:

• For complete shunt occlusion: Administer heparin (50-100 U/kg), increase systemic blood pressure with phenylephrine, and optimize ventilation 1
• Alternative interventions include epinephrine (10 μg/kg), emergent catheterization for thrombus removal, or surgical thrombectomy 1
• ECMO may be required if these measures fail 1

Anticoagulation Strategy

• Maintain anticoagulation with heparin in the immediate post-operative period
• Transition to aspirin or warfarin for long-term management
• Target INR of 1.5-2.5 for patients requiring warfarin 1

Oxygen Management

• Maintain oxygen saturations ≥90% when possible 1
• For patients with right-to-left shunting, supplemental oxygen may help decrease the need for phlebotomy and reduce neurologic complications 1
• Perform both resting and ambulatory pulse oximetry to identify dynamic shunt reversal with exercise 1

Balancing Pulmonary Blood Flow

Managing Excessive Pulmonary Blood Flow

For patients with excessive pulmonary blood flow (high Qp:Qs ratio):

• Consider shunt banding to restrict flow and prevent pulmonary overcirculation 2
• Monitor for signs of volume overload and use diuretics to maintain near-normal intravascular volume 1
• Carefully restrict sodium and fluid intake 1

Managing Inadequate Pulmonary Blood Flow

For patients with inadequate pulmonary blood flow:

• Consider stenting of the ductus arteriosus as an alternative to surgical shunt 3, 4
• Ductal stenting may provide similar outcomes to modified Blalock-Taussig shunts with fewer procedure-related complications 4

Preventing Complications

Infection Prevention

• Immunize against influenza and pneumococcal pneumonia 1
• Aggressively treat respiratory infections when they develop 1

Pulmonary Hypertension Management

• Perform regular echocardiography to screen for pulmonary hypertension 5
• For patients with elevated pulmonary pressures but persistent left-to-right shunting, closure of shunts may improve clinical status 1
• Never close shunts in patients with Eisenmenger physiology (elevated pulmonary pressure with net right-to-left shunting) 1
• Consider inhaled nitric oxide for acute management of pulmonary hypertension crises 6

Monitoring for Pleural Effusions

• Closely monitor for pleural effusions, especially after cavopulmonary anastomosis
• Chylothoraxes increase risk of thrombosis due to loss of proteins C and S 1
• Loss of antithrombin III can limit heparin effectiveness 1

Long-Term Management and Staged Palliation

Bidirectional Cavopulmonary Shunt (BCPS)

• Consider BCPS with additional pulmonary blood flow as an intermediate stage
• This approach provides high survival rates but is not suitable for definitive palliation 7
• Early BCPS with additional pulmonary blood flow may delay the long-term negative consequences of Fontan circulation 7

Timing of Fontan Completion

• Regular assessment of hemodynamics, ventricular function, and pulmonary artery growth
• Perform cardiac catheterization before Fontan completion to evaluate pulmonary vascular resistance and ventricular function
• Risk factors for poor outcomes include older age at BCPS and postoperative complications 7

Surveillance Protocol

• Regular ECG monitoring for patients at risk of tachyarrhythmia, bradyarrhythmia, or heart block 1
• Ambulatory ECG monitoring when symptoms of arrhythmic origin develop 1
• Regular echocardiography to assess shunt patency, pulmonary artery growth, and ventricular function

Special Considerations

Patients with Heterotaxia

• Higher risk for shunt intervention 1
• May require repair of total anomalous pulmonary venous connection at time of shunt placement 1

Patients with Dual Pulmonary Circulation

• More challenging to calculate Qp:Qs accurately due to differences in right/left pulmonary artery blood flow 1
• Rely on invasive hemodynamics including pulmonary vascular resistance for decision-making 1

By following this comprehensive approach to management, patients with shunt-dependent circulation and dual pulmonary circulation can achieve optimal outcomes while minimizing complications as they progress through staged palliation.