Pulmonary Thromboendarterectomy: How I Teach It

Impact of sex on outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension

BACKGROUND

The impact of sex on long-term outcomes after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (PH) remains unclear. We therefore examined the early and long-term outcome after PEA to determine whether sex had an impact on the risk of residual PH and need for targeted PH medical therapy.

METHODS

Retrospective study of 401 consecutive patients undergoing PEA at our institution between August 2005 and March 2020 was performed. Primary outcome was the need for targeted PH medical therapy postoperatively. Secondary outcomes included survival and measures of hemodynamic improvement.

RESULTS

Females (N = 203, 51%) were more likely to have preoperative home oxygen therapy (29.6% vs 11.6%, p < 0.01), and to present with segmental and subsegmental disease compared to males (49.2% vs 21.2%, p < 0.01). Despite similar preoperative values, females had higher postoperative pulmonary vascular resistance (final total pulmonary vascular resistance after PEA, 437 Dynes∙s∙cm-5 vs 324 Dynes∙s∙cm-5 in males, p < 0.01). Although survival at 10 years was not significantly different between sexes (73% in females vs 84% in males, p = 0.08), freedom from targeted PH medical therapy was lower in females (72.9% vs 89.9% in males at 5 years, p < 0.001). Female sex remained an independent factor affecting the need for targeted PH medical therapy after PEA in multivariate analysis (HR 2.03, 95%CI 1.03-3.98, p = 0.04).

CONCLUSIONS

Although outcomes are excellent for both sexes, females had greater need for targeted PH medical therapy in the long-term. Early reassessment and long-term follow-up of these patients are important. Further investigations into possible mechanisms to explain the differences are warranted.

Open Surgical Treatment of Acute and Chronic Pulmonary Embolism

Acute pulmonary embolism (PE) is a common cause of death and morbidity in the United States and the prevalence of chronic thromboembolic pulmonary hypertension (CTEPH), a possible sequela of PE, has increased during the past decade. The mainstay treatment of CTEPH is open pulmonary endarterectomy, a procedure performed under hypothermic circulatory arrest, which entails endarterectomy of the branch, segmental and subsegmental pulmonary arteries. Acute PE may be similarly be treated with an open embolectomy in certain select circumstances.

Advanced Surgical and Percutaneous Approaches to Pulmonary Vascular Disease

Despite progress in modern medical therapy, pulmonary hypertension remains an unremitting disease. Once severe or refractory to medical therapy, advanced percutaneous and surgical interventions can palliate right ventricular overload, bridge to transplantation, and overall extend a patient's course. These approaches include atrial septostomy, Potts shunt, and extracorporeal life support. Bilateral lung transplantation is the ultimate treatment for eligible patients, although the need for suitable lungs continues to outpace availability. Measures such as ex vivo lung perfusion are ongoing to expand donor lung availability, increase rates of transplant, and decrease waitlist mortality.

Endarterectomy for Pulmonary Embolism in a Woman with Unilateral Absence of Pulmonary Artery

Unilateral absence of pulmonary artery (UAPA) is a very rare congenital cardiovascular malformation. To the best of our knowledge, chronic thromboembolic pulmonary hypertension has never been reported in adults with UAPA. In this report, we present the case of a 31-year-old woman with UAPA who developed chronic thromboembolic pulmonary hypertension following multiple episodes of pulmonary embolism due to thrombophilia. Pulmonary thromboendarterectomy was performed, and the short-term outcome was satisfactory.

Pseudo Heparin Resistance After Pulmonary Endarterectomy: Role of Thrombus Production of Factor VIII

Pulmonary endarterectomy (PEA) is the main treatment for chronic thromboembolic pulmonary hypertension (CTEPH). Postoperative unfractionated heparin dosing can be monitored by activated partial thromboplastin time (APTT) or by anti-factor Xa activity (anti-Xa). In pseudo heparin resistance, APTT response to heparin is blunted due to elevated Factor VIII (FVIII) which can underestimate anticoagulation. We examined possible pseudo heparin resistance after PEA and assessed the impact of FVIII. APTT response to heparin before and after operation was determined in 13 PEA patients anticoagulated with unfractionated heparin. APTT and anti-Xa concordance was analyzed from paired postoperative samples, and antithrombin, fibrinogen and FVIII levels were measured. Single-cell RNA sequencing was used to characterize FVIII gene expression in PEA specimens of 5 patients. APTT response to heparin was blunted after PEA. APTT and anti-Xa were discordant in 36% of postoperative samples and most common discordant patterns were subtherapeutic APTT with therapeutic (16%) or supratherapeutic (11%) anti-Xa. Overall, APTT underestimated anticoagulation relative to anti-Xa in one-third of the samples. FVIII levels were elevated before surgery, increased substantially 1 and 3 days (median 4.32 IU/mL) after PEA, and were higher in discordant than concordant samples. Single-cell RNA sequencing showed FVIII gene expression in PEA specimen endothelial cells. Pseudo heparin resistance is common after PEA likely due to highly elevated postoperative FVIII levels indicating that anti-Xa reflects postoperative heparinization better than APTT in these patients. FVIII production by the pulmonary artery endothelium may participate in local prothrombotic processes important for CTEPH pathogenesis.