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Literature Review

Extracorporeal Life Support After Pulmonary Endarterectomy as a Bridge to Recovery or Transplantation: Lessons From 31 Consecutive Patients

Boulate D, Mercier O, Mussot S, et al. Ann Thorac Surg. 2016;102(1):260-268. doi: 10.1016/j.athoracsur.2016.01.103.

Reviewers: Clair Secomb, MD1; Dalia Banks, MD FASE1

  1. University of California, San Diego
Background

Extracorporeal life support (ECLS) can be used to sustain patients having cardiorespiratory failure after pulmonary endarterectomy (PEA). Prior to this study, only two studies have reported outcomes after ECLS as bridge to recovery (BTR) in patients with complications after PEA. These studies were limited by their size and did not identify factors associated with short-term survival. In addition, the existing studies do not examine the feasibility of ECLS as a bridge to transplant (BTT) after PEA. The authors aimed to assess outcomes and to identify factors associated with short-term survival among patients who required ECLS for BTT or BTR after PEA.

Methods

In this retrospective analysis, the investigators identified all patients who underwent PEA at a cardiothoracic hospital in France between January 2005 and July 2013. Patients who received postoperative ECLS were further reviewed. Hemodynamic and outcome data were collected from the early postoperative period and, if available, at the time of discharge or 6 months postoperatively.

Several types of ECLS devices and implantation sites were used. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) was preferred, with either central or peripheral cannulation depending on the timing of cardiorespiratory failure. Pulmonary-artery (PA)-to-left-atrium Novalung was used in 2 patients, and venovenous ECMO was used in 2 patients.

Results

Out of 829 patients who underwent PEA, 31 (3.7%) required postoperative ECLS, including 8 who received a double lung transplant or heart lung transplant (BTT group) and 23 who were supported while awaiting recovery (BTR group). Of the 31 patients, 15 (48.4%) survived to hospital discharge. In the BTT group, 4 out of 8 patients survived to discharge; in the BTR group, 11 out of 23 patients survived to discharge. The BTT group was too small for statistical analysis, but several factors affecting in-hospital survival were identified in the BTR group. The survivors in the BTR group were younger, had larger early mean pulmonary artery pressure (MPAP) decreases, lower post-PEA PA resistance values, and a higher rate of pure respiratory failure. Data collected at discharge or 6 months postoperatively in the 11 BTR survivors showed that early decrease in MPAP persisted or became greater over time.

Comments

Pulmonary endarterectomy is the major lifesaving therapy for patients with chronic thromboembolic pulmonary hypertension; however, life-threatening complications can still occur. This study demonstrated that ECLS is a successful strategy to bridge post-PEA patients with cardiopulmonary failure to recovery or transplant. While post-PEA ECLS has been described in previous reports, this study is the largest. In addition, the study identified factors associated with survival: surviving patients in the BTR group were more likely to be younger, have greater percent decrease in pulmonary artery pressures, and have pure respiratory failure as the reason for ECLS. Regarding the question of which form of ECLS is most favorable, the authors did not have sufficient data for comparison.

The authors suggest that their preference for VA-ECMO led to better outcomes due to the reduction in transpulmonary blood flow on VA-ECMO vs VV-ECMO. In theory, this may lead to reduced airway bleeding, reduced reperfusion pulmonary edema, and reduced right heart strain. However, the small number of patients who received VV-ECMO precluded analysis of survival in VA vs VV-ECMO. Thus, it remains unclear what ECLS strategy is optimal in PEA patients who experience complications. Other limitations acknowledged in this study were the retrospective design and the paucity of long-term follow-up data.

Finally, it seems likely that the results are dependent on the practices and experiences unique to the institution. PEA is performed at relatively few institutions. Among the small number of published reports, rates of post-PEA ECLS range from 1.12% to 5.5% with survival rates of 30% to 57%, and no other institutions have reported attempting organ transplant in post-PEA patients with complications.1,2 This may reflect a lack of experience with distal pulmonary arterial disease at the authors’ institution. An increasingly popular option to treat residual distal arterial disease is balloon angioplasty, which would provide an alternative to transplant in a patient with residual distal disease.3

References
  1. Thistlethwaite PA, Madani MM, Kemp AD, Hartley M, Auger WR, Jamieson SW. Venovenous extracorporeal life support after pulmonary endarterectomy: indications, techniques, and outcomes. Ann Thorac Surg. 2006;82(6):2139–2145.
  2. Berman M, Tsui S, Vuylsteke A, et al. Successful extracorporeal membrane oxygenation support after pulmonary thromboendarterectomy. Ann Thorac Surg. 2008;86(4):1261–1267.
  3. Kataoka M, Inami T, Hayashida K, et al. Percutaneous transluminal pulmonary angioplasty for the treatment of chronic thromboembolic pulmonary hypertension. Circ Cardiovasc Interv. 2012;5(6):756-762.