6. Chronic Thromboembolic Pulmonary Hypertension & Pulmonary Endarterectomy

Quick Recap

1. Definition

CTEPH develops in 3-4% of patients following acute pulmonary embolism — an obstructive vasculopathy from organized thromboembolic material in the pulmonary vascular bed. Mechanisms remain incompletely understood: in situ thrombus propagation, recurrent embolism, thrombus organization, or a secondary obstructive vasculopathy of vessels unaffected by the original embolism itself. Risk factors specific to CTEPH progression: anticardiolipin antibody syndrome, elevated factor VIII, and splenectomy — notably, other procoagulant states have NOT been shown to be associated with CTEPH progression, a genuinely counterintuitive finding given the disease's thromboembolic origin. Pulmonary endarterectomy (PEA) is the established definitive treatment for operable disease.

2. Prognosis and the Case for Intervention

CTEPH carries a genuinely poor prognosis when severe, correlating directly with mean pulmonary artery pressure:

Diagnosis is commonly delayed due to insidious symptom onset and subtle early physical signs — low clinician awareness of the disease is itself a documented contributor to delayed recognition.

3. Operability Assessment — The Jamieson Classification

Virtually all surgical candidates have a pulmonary vascular resistance >300 dyne·sec·cm⁻⁵. Operability decisions are made via multidisciplinary discussion, weighing symptom severity (most surgical patients are NYHA class III-IV), expected natural history, surgical accessibility, and comorbidities. All patients accepted for PEA should have a preoperative IVC filter placed to reduce further thromboembolic events.

4. Surgical Principles

The fundamental aim is a true endarterectomy, not a thrombectomy — surgical success hinges on this distinction. CPB allows continued perfusion during pulmonary artery dissection; periods of deep hypothermic circulatory arrest or selective cerebral perfusion reduce bronchial artery collateral return to the pulmonary arteries, providing a clear operative field (cross-reference Management After Aortic Surgery, this section, for the general DHCA/SACP evidence and controversy).

5. ICU Management — Two Interlinked Central Aims

Keeping the lungs as dry as possible, and minimizing pulmonary vascular resistance — these aims are inextricably linked, since optimal ventilation-perfusion matching, adequate PaO2, minimal PVR, and adequate RV function are all closely interdependent.

Respiratory Targets

• PaO2 >12 kPa, normocapnia, normal acid-base balance, peak airway pressure <30cmH2O
• A genuinely important, non-obvious physiological point: pulmonary vascular resistance reaches its nadir at functional residual capacity (FRC). Raising lung volume above FRC reduces resistance in extra-alveolar vessels (traction-distension effect) but compresses vessels adjacent to the alveoli — above FRC, this latter effect dominates, meaning excessively high ventilation pressures/volumes actively elevate PVR, working directly against the ICU management goal
• Extubation on the first postoperative day is typical; FiO2 is reduced in 5-10% decrements to 40% over the first 6-12 hours, then PEEP weaned to +2cmH2O
• Early chest radiograph is important: check specifically for pulmonary edema and pneumothorax (common after this procedure); diffuse shadowing around the main pulmonary arteries is near-universal and reflects the surgical dissection itself, not a complication
• Avoid peri-extubation hypoxia and respiratory distress — if gas exchange is borderline, follow extubation immediately with mask CPAP rather than risking an oxygenation gap

A Critical, Specific Safety Point — The PA Catheter Balloon

The pulmonary artery catheter balloon must NOT be inflated/wedged after PEA — these patients are at increased risk of pulmonary artery rupture from the surgical dissection that has occurred. Pulmonary artery wedge pressure is instead estimated (rather than directly measured by wedging) to allow pre/postoperative PVR comparison. This is a specific, easily-overlooked, genuinely dangerous pitfall distinct from routine post-cardiac-surgery PA catheter use.

6. Persistent Pulmonary Hypertension and RV Failure — The Major Postoperative Threat

Failure to clear enough disease surgically results in persistent pulmonary hypertension, which can produce fulminant cardiogenic shock and death in theatre at its most severe. Residual PVR >500 predicts a complicated postoperative course.

Presentation: systemic hypotension, low cardiac output, elevated CVP and mean PA pressure, impaired RV free wall motion (directly observed or via TEE).

Management principles (early recognition is essential — RV decompensation can be rapid and often irreversible once established):

• Rest the patient on full bypass if still in theatre
• Optimize loading conditions, guided by hemodynamic trend ± TEE
• Avoid potent vasoconstrictive inotropes where possible; use "inodilating" agents (e.g., enoximone) instead
• Avoid low coronary perfusion pressure — an IABP is often useful here specifically
• Avoid hypoxemia (a reversible pulmonary vascular spasmogen)
• Consider pulmonary vasodilator therapy

A critical, specific numeric target and warning: intravascular filling to a CVP of 10-14mmHg, targeting MAP ≥60mmHg, while avoiding hypoxemia, may allow survival. Overfilling (CVP >14-15mmHg) commonly triggers a self-reinforcing decline: incremental tricuspid regurgitation → falling forward flow → reduced systemic perfusion pressure gradient → further decline — this spiral has low salvage potential and must be avoided at all costs, making CVP a genuinely bidirectional risk (too little and too much both carry real danger) rather than a simple "more fluid is better" scenario.

Long-term pulmonary vasodilator therapy (bosentan or sildenafil) is prudent for patients who survive this initial phase.

Other Contributing Factors to Persistent PVR/RV Failure (Worth Actively Screening For)

• Pulmonary vascular spasmogens: hypoxia, inappropriate vasopressor use, mediators released from platelet/FFP transfusion
• High-volume/high-pressure ventilation strategy (cross-reference the FRC principle, Section 5)
• Incoordinate spontaneous ventilatory efforts — inadequate sedation causing "fighting the ventilator," or a turbulent peri-extubation period
• RV-specific factors: poor preoperative RV function, faulty intraoperative myocardial protection, inadequate coronary perfusion pressure gradient
• ECMO may be the only remaining option if these interventions fail

7. Pulmonary Hemorrhage — A Rare But Genuinely Feared Complication

Results from inadvertent pulmonary arterial wall perforation during endarterectomy — even a normal pulmonary artery is more friable than a comparable systemic artery; risk factors include calcified/adherent disease, dissecting in too deep a plane, excess force, or poor visualization.

If recognized intraoperatively and sufficiently proximal, fine-suture repair may be possible. More commonly, perforation is unrecognized until weaning from CPB, presenting as massive hemoptysis — a genuine emergency requiring:

• Immediate double-lumen endotracheal tube placement to isolate the lungs from one another, preventing asphyxiation
• Active avoidance of any fall in PaO2 — hypoxic pulmonary vasoconstriction could trigger a precipitous pulmonary arterial pressure rise, worsening the bleeding physiology
• Fiberoptic bronchoscopy has little value at this stage — ineffective for airway toilet, may not localize the bleeding source, and delays definitive contralateral lung protection
• Subsequent single-lung ventilation and reversal of systemic anticoagulation may arrest the hemorrhage
• Mortality remains high even with prompt, correct management

8. Modern Development — Balloon Pulmonary Angioplasty for Inoperable Disease

Balloon pulmonary angioplasty (BPA) has emerged as an established option specifically for patients with inoperable CTEPH (Jamieson type 4, or prohibitive surgical comorbidity) — a genuinely important addition not present in the 2008 source text, since up to a third of CTEPH patients may still be considered inoperable even with modern surgical technique advances.

• 2022 ESC/ERS pulmonary hypertension guidelines recommend BPA as Class I for inoperable disease or residual symptomatic CTEPH after PEA
• RACE trial (BPA vs. riociguat, inoperable CTEPH): BPA produced greater reduction in PVR and mean PA pressure than riociguat, though with a higher incidence of procedure-related complications
• "Refined BPA" technique (pressure-wire guidance, undersized balloons in initial sessions) has substantially improved safety compared to earlier US experience, which showed high complication rates (mortality, hemoptysis, need for positive-pressure ventilation) and led to initially poor US adoption — the technique has since evolved considerably
• Vascular injury remains a major cause of lung injury specifically after BPA — a genuine, procedure-specific complication requiring its own recognition and management approach at centers performing this procedure
• Practical implication: BPA is increasingly used as either a primary option for truly inoperable disease, or as a sequential/combination strategy with medical vasodilator therapy — not necessarily as a strict either/or alternative to PEA, but as a complementary tool for the specific subset PEA cannot address

9. Outcomes

Overall in-hospital mortality is 5-10% at experienced centers. With good disease clearance, hemodynamic improvement, and absence of reperfusion pulmonary edema, discharge within 7-10 days is achievable. Long-term data suggest sustained, marked symptomatic improvement with approximately 75% 5-year survival — favorable compared to both the natural history of unoperated disease and the competing alternative of lung (± heart) transplantation.

10. Consultation Matrix

11. Documentation & Medicolegal Checklist

• Jamieson type and operability assessment/multidisciplinary decision documented
• Explicit note in the chart/handoff that PA catheter balloon must NOT be inflated/wedged post-PEA
• CVP trend and rationale for fluid management documented, given the narrow, bidirectional safe range

12. Key Guidelines

• 2022 ESC/ERS pulmonary hypertension guidelines provide current BPA (Class I for inoperable/residual disease) and overall CTEPH management recommendations

13. Landmark Evidence

14. Controversies

• The CVP target range for post-PEA RV support is genuinely narrow and bidirectionally dangerous — this protocol emphasizes that both under- and over-filling carry real, distinct risks, a less commonly appreciated nuance than the more familiar "more fluid helps low output" heuristic used elsewhere in cardiac surgery.
• BPA's complication rate remains genuinely higher than optimal, even with refined technique — this protocol does not present BPA as a risk-free alternative to PEA, but as a genuinely valuable option specifically for patients who have no surgical alternative.

15. References

1. Thomson B, Jenkins DP. Chronic thromboembolic pulmonary hypertension and pulmonary endarterectomy. In: Klein AA, Vuylsteke A, Nashef SAM, eds. Core Topics in Cardiothoracic Critical Care. Cambridge: Cambridge University Press; 2008:395-401.
2. Jamieson SW, Kapelanski DP, Sakakibara N, et al. Pulmonary endarterectomy: experience and lessons learned in 1500 cases. Ann Thorac Surg. 2003;76:1457-1464.
3. Jais X, Brenot P, Bouvaist H, et al. Balloon pulmonary angioplasty versus riociguat for the treatment of inoperable chronic thromboembolic pulmonary hypertension (RACE). Lancet Respir Med. 2022;10(10):961-971.
4. Humbert M, Kovacs G, Hoeper MM, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J. 2022;43(38):3618-3731.
5. Balloon pulmonary angioplasty in the current era of CTEPH treatment: how did we get here? Pulm Circ. 2023.
6. Refined Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Hypertension: Initial Results of U.S. Regional Program. JACC Adv. 2023.

See also: Management After Aortic Surgery (Root/Arch), this section, for the general DHCA/SACP evidence used during PEA; Massive & Submassive PE (Cardiovascular System) for the acute PE population that a minority progress from into CTEPH; Post-Cardiotomy Mechanical Circulatory Support (this section) for ECMO escalation in refractory RV failure.