Severe Pulmonary Arteriopathy Is Associated with Persistent Hypoxemia after Pulmonary Endarterectomy in Chronic Thromboembolic Pulmonary Hypertension

Abstract

BackgroundChronic thromboembolic pulmonary hypertension (CTEPH) is characterized by occlusion of pulmonary arteries by organized chronic thrombi. Persistent hypoxemia and residual pulmonary hypertension (PH) following successful pulmonary endarterectomy (PEA) are clinically important problems; however, the underlying mechanisms remain unclear. We have previously reported that residual PH is closely related to severe pulmonary vascular remodeling and hypothesize that this arteriopathy might also be involved in impaired gas exchange. The purpose of this study was to evaluate the association between hypoxemia and pulmonary arteriopathy after PEA.Methods and ResultsBetween December 2011 and November 2014, 23 CTEPH patients underwent PEA and lung biopsy. The extent of pulmonary arteriopathy was quantified pathologically in lung biopsy specimens. We then analyzed the relationship between the severity of pulmonary arteriopathy and gas exchange after PEA. We observed that the severity of pulmonary arteriopathy was negatively correlated with postoperative and follow-up PaO2 (postoperative PaO2: r = -0.73, p = 0.0004; follow-up PaO2: r = -0.66, p = 0.001), but not with preoperative PaO2 (r = -0.373, p = 0.08). Multivariate analysis revealed that the obstruction ratio and patient age were determinants of PaO2 one month after PEA (R2 = 0.651, p = 0.00009). Furthermore, the obstruction ratio and improvement of pulmonary vascular resistance were determinants of PaO2 at follow-up (R2 = 0.545, p = 0.0002). Severe pulmonary arteriopathy might increase the alveolar-arterial oxygen difference and impair diffusion capacity, resulting in hypoxemia following PEA.ConclusionThe severity of pulmonary arteriopathy was closely associated with postoperative and follow-up hypoxemia.

Critical Care of Patients After Pulmonary Thromboendarterectomy

“…Slow weaning of iNO and F I O 2 often is warranted in patients with severe post-PTE hypoxia, and supplemental oxygen may be needed for months after hospital discharge. 71,87 Throughout the early postoperative period, continuous diuresis for daily negative fluid balances while avoiding overt injury to the kidneys is crucial to minimize further compromise from coexisting pulmonary edema.…”

Involvement of pulmonary arteriopathy in the development and severity of reperfusion pulmonary edema after pulmonary endarterectomy

“…Determination of a definitive diagnosis and an examination including right heart catheterization were performed at the preoperative period and a complete examination was performed one month and one year after PEA in all patients, as previously reported. 9,10 The hemodynamic data soon after PEA were collected from the patients' ICU records. The hemodynamic data were measured using CCOmbo Catheters (774F75, Edwards Lifesciences, Irvine, CA, USA).…”

“…PEA was performed by KI and MM at Chiba University Hospital. The indications for PEA were as follows 10 : (1) mPAP ≥ 25 mmHg; (2) pulmonary vascular resistance (PVR) > 300 dyne·s·cm −5 ; (3) World Health Organization (WHO) functional class ≥ 2; (4) technically operable; (5) no significant co-morbidity; and (6) full understanding of the benefits and the risks. The Jamieson's classification was determined during the operation by two experienced cardiovascular surgeons (KI and MM), as previously reported.…”

“…Two trained investigators (TJ-S and HI-U) conducted a pathological evaluation of pulmonary arteriopathy and venopathy based on methods described previously. 9,10 All pulmonary muscular arteries with adjacent bronchioles were recorded. The inclusion criteria of pulmonary arteries in the current study were as follows: (1) the horizontal-to-vertical ratio of these vessels was <1:2; and (2) the vascular diameter was <300 µm.…”

“…The biopsied lung tissue was prepared based on methods described previously. 9,10 In total, 781 slices were prepared, stained using the Elastica-van Gieson method, and analyzed pathologically, as described in the following section.…”