What is the best management approach for a patient with pulmonary thromboembolism (PTE) who has undergone deep hypothermic circulatory arrest (DHCA)?

Management of Pulmonary Thromboembolism (PTE) with Deep Hypothermic Circulatory Arrest (DHCA)

Surgical pulmonary endarterectomy (PEA) performed under deep hypothermic circulatory arrest is the recommended treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH), with current in-hospital mortality as low as 4.7% and the majority of patients experiencing substantial symptom relief and near-normalization of hemodynamics. 1

Surgical Technique and Approach

The standard PEA procedure requires:

• Median sternotomy with cardiopulmonary bypass 1
• Profound induced hypothermia with periods of full circulatory arrest during which thromboembolic material dissection is accomplished 1
• True bilateral endarterectomy through the medial layer of the pulmonary arteries 1
• Deep hypothermia with intermittent circulatory arrest, without need for cerebral perfusion 1

The procedure achieves significantly lower pulmonary artery pressures and vascular resistance immediately post-operatively, with mean pulmonary artery pressure decreasing from 91.4 ± 22.4 to 48.3 ± 10.7 mmHg and cardiac index increasing from 1.64 ± 0.47 to 2.58 ± 0.51 L/min/m² 2

Pre-Operative Requirements

All patients must undergo multidisciplinary team evaluation before surgery: 1

• Experienced PEA surgeons
• Interventional radiologists or cardiologists
• Radiologists with pulmonary vascular imaging expertise
• Clinicians with pulmonary hypertension expertise

Confirm CTEPH diagnosis requires: 1

• At least 3 months of effective anticoagulation to distinguish from acute PE
• Mean pulmonary artery pressure ≥25 mmHg with pulmonary arterial wedge pressure ≤15 mmHg on right heart catheterization
• Mismatched perfusion defects on V/Q lung scan
• Specific CT angiography findings: ring-like stenoses, webs, slits, or chronic total occlusions

Surgical accessibility criteria include: 1

• Pre-operative NYHA functional class assessment
• Thrombi located in main, lobar, or segmental pulmonary arteries 1
• Advanced age alone is not a contraindication 1
• No specific haemodynamic threshold or RV dysfunction measure precludes PEA 1

Peri-Operative Anticoagulation Management

Standard approach: 3

• Initial dose: 5,000 units heparin by intravenous injection 3
• Continuous infusion: 20,000 to 40,000 units/24 hours in 1,000 mL of 0.9% Sodium Chloride 3
• Monitor aPTT to maintain 1.5 to 2 times normal 3

For patients with heparin-induced thrombocytopenia (HIT):

• Cangrelor combined with heparin has been successfully used during cardiopulmonary bypass and DHCA 4
• This approach avoids significant postoperative bleeding associated with alternative anticoagulants 4

Post-Operative Management

Immediate post-operative monitoring focuses on: 5, 2

• Pulmonary complications including hypoxemia and right heart failure 5
• Lower post-CPB pulmonary vascular resistance predicts reduced length of postoperative ventilation 5
• Relatively decreased central venous pressure (from pre-CPB values) correlates with shorter ventilation time 5

Key perfusion management strategies include: 2

• Myocardial and cerebral protection
• Lung protection during DHCA
• Ultrafiltration and cell-saving techniques 2

Common pitfall: Body mass index significantly higher in non-survivors, suggesting increased mortality risk in patients with large body habitus 5

Long-Term Anticoagulation

Life-long anticoagulation is mandatory in all CTEPH patients: 1

• Class I, Level C recommendation 1
• Continue indefinitely regardless of surgical success 1

Alternative Treatments for Inoperable or Residual Disease

If patients are deemed inoperable or have persistent/recurrent CTEPH after surgery: 1

• Riociguat is recommended (Class I, Level B) 1
• Off-label use of PAH-approved drugs may be considered (Class IIb, Level B) 1
• Interventional balloon pulmonary angioplasty may be considered for technically non-operable patients (Class IIb, Level C) 1

Outcomes and Follow-Up

Expected survival outcomes: 1

• 3-year survival: 89% in operated patients versus 70% in non-operated patients 1
• Mortality associated with NYHA functional class, right atrial pressure, and history of cancer 1

Long-term follow-up shows: 2

• 22 of 26 patients in NYHA class 1 at mean 36.8 months follow-up
• 3 patients in class 2, and 1 in class 3 2