Central venoarterial extracorporeal membrane oxygenation as a bridge to recovery after pulmonary endarterectomy in patients with decompensated right heart failure

Chronic thromboembolic pulmonary disease

Chronic thromboembolic pulmonary hypertension is a complication of pulmonary embolism and a treatable cause of pulmonary hypertension. The pathology is a unique combination of mechanical obstruction due to failure of clot resolution, and a variable degree of microvascular disease, that both contribute to pulmonary vascular resistance. Accordingly, multiple treatments have been developed to target the disease components. However, accurate diagnosis is often delayed. Evaluation includes high-quality imaging modalities, necessary for disease confirmation and for appropriate treatment planning. All patients with chronic thromboembolic pulmonary disease, and especially those with pulmonary hypertension, should be referred to expert centres for multidisciplinary team decision on treatment. The first decision remains assessment of operability, and the best improvement in symptoms and survival is achieved by the mechanical therapies, pulmonary endarterectomy and balloon pulmonary angioplasty. With the advances in multimodal therapies, excellent outcomes can be achieved with 3-year survival of >90%.

Transplantation, bridging, and support technologies in pulmonary hypertension

Despite the progress made in medical therapies for treating pulmonary hypertension (PH), a subset of patients remain susceptible to developing a maladaptive right ventricular phenotype. The effective management of end-stage PH presents substantial challenges, necessitating a multidisciplinary approach and early identification of patients prone to acute decompensation. Identifying potential transplant candidates and assessing the feasibility of such a procedure are pivotal tasks that should be undertaken early in the treatment algorithm. Inclusion on the transplant list is contingent upon a comprehensive risk assessment, also considering the specific type of PH and various factors affecting waiting times, all of which should inform the decision-making process. While bilateral lung transplantation is the preferred option, it demands expert intra- and post-operative management to mitigate the heightened risks of pulmonary oedema and primary graft dysfunction in PH patients. Despite the availability of risk assessment tools, the occurrence of acute PH decompensation episodes can be unpredictable, potentially leading to refractory right ventricular failure even with optimal medical intervention, necessitating the use of rescue therapies. Advancements in right ventricular assist techniques and adjustments to graft allocation protocols for the most critically ill patients have significantly enhanced the survival in intensive care, affording the opportunity to endure while awaiting an urgent transplant. Given the breadth of therapeutic options available, specialised centres capable of delivering comprehensive care have become indispensable for optimising patient outcomes. These centres are instrumental in providing holistic support and management tailored to the complex needs of PH patients, ultimately enhancing their chances of a successful transplant and improved long-term prognosis.

Pulmonary Thromboendarterectomy: The Potentially Curative Treatment of Choice for Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a consequence of unresolved organized thromboembolic obstruction of the pulmonary arteries, which can cause pulmonary hypertension and right ventricular failure. Owing to its subtle signs, determining its exact incidence and prevalence is challenging. Furthermore, CTEPH may also present without any prior venous thromboembolic history, contributing to underdiagnosis and undertreatment. Diagnosis requires a high degree of suspicion and is ruled out by a normal ventilation/perfusion ratio scintigraphy. Additional imaging by computed tomography and/or conventional angiography, as well as right heart catheterization, are required to confirm CTEPH and formulate treatment plans. Pulmonary thromboendarterectomy is the treatment of choice for eligible patients and can be potentially curative. Pulmonary thromboendarterectomy has a low mortality rate of 1% to 2% at expert centers and offers excellent long-term survival. Furthermore, recent advances in the techniques allow distal endarterectomy with comparable outcomes. Alternative treatment options are available for those who may not be operable or have prohibitive risks, providing some benefit. However, CTEPH is a progressive disease with low long-term survival rates if left untreated. Given excellent short- and long-term outcomes of surgery, as well as the benefits seen with other treatment modalities in noncandidate patients, it is crucial that precapillary pulmonary hypertension and CTEPH are ruled out in any patient with dyspnea of unexplained etiology. These patients should be referred to expert centers where accurate operability assessment and appropriate treatment strategies can be offered by a multidisciplinary team.

New-onset postoperative atrial fibrillation after pulmonary endarterectomy is associated with adverse outcomes

Background

New-onset postoperative atrial fibrillation (POAF) is a common complication after pulmonary thromboendarterectomy (PEA), yet the risk factors and their impact on prognosis remain poorly understood. This study aims to investigate the risk factors associated with new-onset POAF after PEA and elucidate its underlying connection with adverse postoperative outcomes.

Methods

A retrospective analysis included 129 consecutive chronic thromboembolic pulmonary hypertension (CTEPH) patients and 16 sarcoma patients undergoing PEA. Univariate and multivariate analyses were conducted to examine the potential effects of preoperative and intraoperative variables on new-onset POAF following PEA. Propensity score matching (PSM) was then employed to adjust for confounding factors.

Results

Binary logistic regression revealed that age (odds ratio [OR] = 1.041, 95% confidence interval [CI] = 1.008-1.075, p = 0.014) and left atrial diameter[LAD] (OR = 1.105, 95% CI = 1.025-1.191, p = 0.009) were independent risk factors for new-onset POAF after PEA. The receiver operating characteristic (ROC) curve indicated that the predictive abilities of age and LAD for new-onset POAF were 0.652 and 0.684, respectively. Patients with new-onset POAF, compared with those without, exhibited a higher incidence of adverse outcomes (in-hospital mortality, acute heart failure, acute kidney insufficiency, reperfusion pulmonary edema). Propensity score matching (PSM) analyses confirmed the results.

Conclusion

Advanced age and LAD independently contribute to the risk of new-onset POAF after PEA. Patients with new-onset POAF are more prone to adverse outcomes. Therefore, heightened vigilance and careful monitoring of POAF after PEA are warranted.

How Would I Treat My Own Chronic Thromboembolic Pulmonary Hypertension in the Perioperative Period?

Chronic thromboembolic pulmonary hypertension (CTEPH) results from an incomplete resolution of acute pulmonary embolism, leading to occlusive organized thrombi, vascular remodeling, and associated microvasculopathy with pulmonary hypertension (PH). A definitive CTEPH diagnosis requires PH confirmation by right-heart catheterization and evidence of chronic thromboembolic pulmonary disease on imaging studies. Surgical removal of the organized fibrotic material by pulmonary endarterectomy (PEA) under deep hypothermic circulatory arrest represents the treatment of choice. One-third of patients with CTEPH are not deemed suitable for surgical treatment, and medical therapy or interventional balloon pulmonary angioplasty presents alternative treatment options. Pulmonary endarterectomy in patients with technically operable disease significantly improves symptoms, functional capacity, hemodynamics, and quality of life. Perioperative mortality is <2.5% in expert centers where a CTEPH multidisciplinary team optimizes patient selection and ensures the best preoperative optimization according to individualized risk assessment. Despite adequate pulmonary artery clearance, patients might be prone to perioperative complications, such as right ventricular maladaptation, airway bleeding, or pulmonary reperfusion injury. These complications can be treated conventionally, but extracorporeal membrane oxygenation has been included in their management recently. Patients with residual PH post-PEA should be considered for medical or percutaneous interventional therapy.

Perioperative extracorporeal membrane oxygenation support for pulmonary endarterectomy: A 17-year experience from the UK national cohort

BACKGROUND

Pulmonary endarterectomy (PEA) is the guideline-recommended treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients develop severe cardiopulmonary compromise before surgery, intraoperatively, or early postoperatively. This may result from advanced CTEPH, reperfusion pulmonary edema, massive endobronchial bleeding, or right ventricular (RV) failure secondary to residual pulmonary hypertension. Conventional cardiorespiratory support is ineffective when these complications are severe. Since 2005, we used extracorporeal membrane oxygenation (ECMO) as a rescue therapy for this group. We review our experience with ECMO support in these patients.

METHODS

This study was a retrospective analysis of patients who received perioperative ECMO for PEA from a single national center from August 2005 to July 2022. Data were prospectively collected.

RESULTS

One hundred and ten patients (4.7%) had extreme cardiorespiratory compromise requiring perioperative ECMO. Nine were established on ECMO before PEA. Of those who received ECMO postoperatively, 39 were for refractory reperfusion lung injury, 20 for RV failure, 31 for endobronchial bleeding, and the remaining 11 were for "other" reasons, such as cardiopulmonary resuscitation following late tamponade and aspiration pneumonitis. Sixty-two (56.4%) were successfully weaned from ECMO. Fifty-seven patients left the hospital alive, giving a salvage rate of 51.8%. Distal disease (Jamieson Type III) and significant residual pulmonary hypertension were also predictors of mortality on ECMO support. Overall, 5- and 10-year survival in patients who were discharged alive following ECMO support was 73.9% (SE: 6.1%) and 58.2% (SE: 9.5%), respectively.

CONCLUSIONS

Perioperative ECMO support has an appropriate role as rescue therapy for this group. Over 50% survived to hospital discharge. These patients had satisfactory longer-term survival.

Extracorporeal Life Support in Pulmonary Hypertension: Practical Aspects

Extracorporeal life support (ECLS), in particular veno-arterial extracorporeal membrane oxygenation, has emerged as a potentially life-saving treatment modality in patients presenting with pulmonary hypertension and right heart failure refractory to conventional treatment. Used mainly as a bridge to lung transplantation, ECLS is also being used occasionally as a bridge to recovery in patients with treatable causes of right heart failure. This review article describes indications, contraindications, techniques, and outcomes of the use of ECLS in patients with PH, focusing on practical aspects in the management of such patients.

Use of Perioperative Extracorporeal Membranous Oxygenation in Pulmonary Endarterectomy Cases: A Systematic Review and Meta-Analysis

Introduction: Pulmonary endarterectomy (PEA) is known to be a curative intervention for chronic thromboembolic pulmonary hypertension (CTEPH). Its complications include endobronchial bleeding, persistent pulmonary arterial hypertension, right ventricular failure, and reperfusion lung injury. Extracorporeal membranous oxygenation (ECMO) is a perioperative salvage method for PEA. Although risk factors and outcomes have been reported in several studies, overall trends remain unknown. We performed a systematic review and study-level meta-analysis to understand the outcomes of ECMO utilization in the perioperative period of PEA. Methods: We performed a literature search with PubMed and EMBASE on 11/18/2022. We included studies including patients who underwent perioperative ECMO in PEA. We collected data including baseline demographics, hemodynamic measurements, and outcomes such as mortality and weaning of ECMO and performed a study-level meta-analysis. Results: Eleven studies with 2632 patients were included in our review. ECMO insertion rate was 8.7% (225/2,625, 95% CI 5.9-12.5) in total, VV-ECMO was performed as the initial intervention in 1.1% (41/2,625, 95% CI 0.4-1.7) (Figure 3), and VA-ECMO was performed as an initial intervention in 7.1% (184/2,625, 95% CI 4.7-9.9). Preoperative hemodynamic measurements showed higher pulmonary vascular resistance, mean pulmonary arterial pressure, and lower cardiac output in the ECMO group. Mortality rates were 2.8% (32/1238, 95% CI: 1.7-4.5) in the non-ECMO group and 43.5% (115/225, 95% CI: 30.8-56.2) in the ECMO group. The proportion of patients with successful weaning of ECMO was 72.6% (111/188, 95% CI: 53.4-91.7). Regarding complications of ECMO, the incidence of bleeding and multi-organ failure were 12.2% (16/79, 95% CI: 13.0-34.8) and 16.5% (15/99, 95% CI: 9.1-28.1), respectively. Conclusion: Our systematic review showed a higher baseline cardiopulmonary risk in patients with perioperative ECMO in PEA, and its insertion rate was 8.7%. Further studies that compare the use of ECMO in high-risk patients who undergo PEA are anticipated.

Preoperative pulmonary vascular resistance and neutrophil-to-lymphocyte ratio predict the demand of extracorporeal membrane oxygenation after pulmonary endarterectomy

BACKGROUND

Acute respiratory and circulatory collapse might occasionally happen after pulmonary endarterectomy (PEA). We aimed to investigate the utilization of extracorporeal membrane oxygenation (ECMO) after PEA and potential risk factors.

METHODS

Demographic characteristics, clinical and surgical data were collected for all patients who underwent PEA from December 2016 to June 2022. All factors were compared between patients in the ECMO group and those in the other group. The most characteristic risk factors were obtained by least absolute shrinkage and selection operator regression and support vector machine machine learning, and receiver operating characteristics (ROC) Curve analysis was performed to verify the diagnostic value of the obtained risk factors.

RESULTS

A total of 117 patients underwent PEA, and 8 (6.8%) of them received ECMO treatment intraoperatively or postoperatively. There were significant differences between the two groups in terms of cardiac function, pulmonary vascular resistance (PVR), preoperative inflammation and cardiopulmonary bypass time. The PVR and neutrophil-to-lymphocyte ratio (N/L ratio) were the most characteristic risk factors with an area under the ROC curve of 0.847 (95% confidence interval [CI] = 0.7517-0.9420, p = .005) and 0.896 (95% CI = 0.803-0.989, p = .001), respectively. The ECMO group had higher PVR (1549.4 ± 600.7 vs. 952.9 ± 466.9 dyn.s.cm^-5 , p = .004) and N/L ratio (6.3 ± 5.6 vs. 2.4 ± 1.7, p = .001).

CONCLUSIONS

PVR and N/L ratio can correctly predict who is likely to receive ECMO treatment after PEA. Therefore, addressing the preoperative inflammatory status might be beneficial but further research is needed.

Mechanical circulatory support devices and treatment strategies for right heart failure

The importance of right heart failure (RHF) treatment is magnified over the years due to the increased risk of mortality. Additionally, the multifactorial origin and pathophysiological mechanisms of RHF render this clinical condition and the choices for appropriate therapeutic target strategies remain to be complex. The recent change in the United Network for Organ Sharing (UNOS) allocation criteria of heart transplant may have impacted for the number of left ventricular assist devices (LVADs), but LVADs still have been widely used to treat advanced heart failure, and 4.1 to 7.4% of LVAD patients require a right ventricular assist device (RVAD). In addition, patients admitted with primary left ventricular failure often need right ventricular support. Thus, there is unmet need for temporary or long-term support RVAD implantation exists. In RHF treatment with mechanical circulatory support (MCS) devices, the timing of the intervention and prediction of duration of the support play a major role in successful treatment and outcomes. In this review, we attempt to describe the prevalence and pathophysiological mechanisms of RHF origin, and provide an overview of existing treatment options, strategy and device choices for MCS treatment for RHF.

Role of extracorporeal membrane oxygenation and surgical embolectomy in acute pulmonary embolism

PURPOSE OF REVIEW

Surgery is an important option to consider in patients with massive and submassive pulmonary emboli. Earlier intervention, better patient selection, improved surgical techniques and the use of veno-arterial extracorporeal membrane oxygenation (VA ECMO) have contributed to improve the safety of surgery for pulmonary emboli.

RECENT FINDINGS

VA ECMO is rapidly changing the initial management of patients with massive pulmonary emboli, providing an opportunity for stabilization and optimization before intervention. The early and long-term consequences of acute pulmonary emboli are better understood, in particular with regard to the risks of chronic thromboembolic pulmonary hypertension (CTEPH), an entity that should be identified in the acute setting as much as possible. The presence of chronic thromboembolic pulmonary disease can be associated with persistent haemodynamic instability despite removal of the acute thrombi, particularly if pulmonary hypertension is established. The pulmonary embolism response team (PERT) is an important component in the management of massive and submassive acute pulmonary emboli to determine the best treatment options for each patient depending on their clinical presentation.

SUMMARY

Three types of surgery can be performed for pulmonary emboli depending on the extent and degree of organization of the thrombi (pulmonary embolectomy, pulmonary thrombo-embolectomy and pulmonary thrombo-endarterectomy). Other treatment options in the context of acute pulmonary emboli include thrombolysis and catheter-directed embolectomy. Future research should determine how best to integrate VA ECMO as a bridging strategy to recovery or intervention in the treatment algorithm of patients with acute massive pulmonary emboli.

An Update on the Management of Acute High-Risk Pulmonary Embolism

Hemodynamic instability and right ventricular (RV) dysfunction are the key determinants of short-term prognosis in patients with acute pulmonary embolism (PE). High-risk PE encompasses a wide spectrum of clinical situations from sustained hypotension to cardiac arrest. Early recognition and treatment tailored to each individual are crucial. Systemic fibrinolysis is the first-line pulmonary reperfusion therapy to rapidly reverse RV overload and hemodynamic collapse, at the cost of a significant rate of bleeding. Catheter-directed pharmacological and mechanical techniques ensure swift recovery of echocardiographic parameters and may possess a better safety profile than systemic thrombolysis. Further clinical studies are mandatory to clarify which pulmonary reperfusion strategy may improve early clinical outcomes and fill existing gaps in the evidence.

Pulmonary endarterectomy in severe chronic thromboembolic pulmonary hypertension: the Toronto experience

BACKGROUND

Pulmonary endarterectomy (PEA) in severe chronic thromboembolic pulmonary hypertension (CTEPH) is associated with higher risks. However, recent evidence suggests that these risks may be mitigated with the use of extracorporeal membrane oxygenation (ECMO).

METHODS

We performed a retrospective analysis of 401 consecutive patients undergoing PEA at the Toronto General Hospital between August 2005 and March 2020. Patients with severe CTEPH defined by pulmonary vascular resistance (PVR) >1,000 dynes.s.cm-5 at the time of diagnosis were compared to those with PVR <1,000 dynes.s.cm-5.

RESULTS

The New York Heart Association (NYHA) functional class, brain natriuretic peptide (BNP) and 6-minute walk distance were worse in patients with PVR >1,000 dynes.s.cm-5. A greater proportion of patients with PVR >1,000 dynes.s.cm-5 was treated with targeted pulmonary hypertension (PH) medical therapy (38% vs. 18%, P<0.001) and initiated on inotropic support (7% vs. 0.3%, P<0.001) before PEA. Since 2014, the ECMO utilization rate increased in patients with PVR >1,000 dynes.s.cm-5 compared to those with PVR <1,000 dynes.s.cm-5 (18% vs. 3.1%, P<0.001). The hospital mortality in patients with PVR >1,000 dynes.s.cm-5 decreased from 10.3% in 2005-2013 to 1.6% in 2014-2020 (P=0.05), while the hospital mortality in patients with PVR <1,000 dynes.s.cm-5 remained stable (1.2% in 2005-2013 vs. 2.7% in 2014-2020, P=0.4). The overall survival reached 84% at 10 years in patients with PVR >1,000 dynes.s.cm-5 compared to 78% in patients with PVR <1,000 dynes.s.cm-5 (P=0.7).

CONCLUSIONS

The early and long-term results of PEA in patients with severe CTEPH are excellent despite greater postoperative risks. ECMO as a bridge to recovery after PEA can be useful in patients with severe CTEPH.