Anatomical risk factors, surgical treatment, and clinical outcomes of left-sided pulmonary vein obstruction in single-ventricle patients

A neonatal rat model of pulmonary vein stenosis

OBJECTIVES

Pulmonary vein stenosis (PVS), one of the most challenging clinical problems in congenital heart disease, leads to secondary pulmonary arterial hypertension (PAH) and right ventricular (RV) hypertrophy. Due to the lack of a rodent model, the mechanisms underlying PVS and its associated secondary effects are largely unknown, and treatments are minimally successful. This study developed a neonatal rat PVS model with the aim of increasing our understanding of the mechanisms and developing possible treatments for PVS.

METHODS

PVS was created at postnatal day 1 (P1) by banding pulmonary veins that receive blood from the right anterior and mid lobes. The condition was confirmed using echocardiography, computed tomography (CT), gross anatomic examination, hematoxylin and eosin (H&E) staining, fibrosis staining, and immunofluorescence. Lung and RV remodeling under the condition of PVS were evaluated using H&E staining, fibrosis staining, and immunofluorescence.

RESULTS

At P21, echocardiography revealed a change in wave form and a decrease in pulmonary artery acceleration time-indicators of PAH-at the transpulmonary valve site in the PVS group. CT at P21 showed a decrease in pulmonary vein diameter in the PVS group. At P30 in the PVS group, gross anatomic examination showed pulmonary congestion, H&E staining showed wall thickening and lumen narrowing in the upstream pulmonary veins, and immunofluorescence showed an increase in the smooth muscle layers in the upstream pulmonary veins. In addition, at P30 in the PVS group, lung remodeling was evidenced by hyperemia, thickening of pulmonary small vessel walls and smooth muscle layers, and reduction of the number of alveoli. RV remodeling was evidenced by an increase in RV free wall thickness.

CONCLUSIONS

A neonatal rat model of PVS was successfully established, showing secondary lung and RV remodeling. This model may serve as a useful platform for understanding the mechanisms and treatments for PVS.

Pulmonary vein stenosis: Anatomic considerations, surgical management, and outcomes

OBJECTIVE

The study objective was to evaluate outcomes of pulmonary vein stenosis repair in a large single-center cohort.

METHODS

Clinical data from a pulmonary vein stenosis registry were retrospectively reviewed identifying patients who underwent pulmonary vein stenosis repair. The primary/index operation was defined as the patient's first pulmonary vein stenosis operation during the study period.

RESULTS

Between January 2007 and August 2019, 174 patients underwent pulmonary vein stenosis repair. Bilateral pulmonary vein stenosis occurred in 111 patients (64%); 71 patients (41%) had 4-vessel disease. Fifty-nine patients (34%) had primary pulmonary vein stenosis. Median age was 9 months (interquartile range, 5-27) and weight was 6.5 kg (4.7-10.2). Surgical techniques evolved and included ostial resection, unroofing, reimplantation, sutureless, modified sutureless, and a newer anatomically focused approach of pulmonary vein stenosis resection with lateralization or patch enlargement of the pulmonary vein-left atrium connection. Twenty-three patients (13%) required reoperation. Cumulative 2-year incidence of postoperative transcatheter intervention (balloon dilation ± stenting) was 64%. One-, 2-, and 5-year survivals were 71.2%, 66.8%, and 60.6%, respectively. There was no association between surgery type and reoperation rate (hazard ratio, 2.38, P = .25) or transcatheter intervention (hazard ratio, 0.97, P = .95). The anatomically focused repair was associated with decreased mortality on univariate (hazard ratio, 0.38, P = .042) and multivariable analyses (hazard ratio, 0.19, P = .014). Antiproliferative chemotherapy was also associated with decreased mortality (hazard ratio, 0.47, P = .026).

CONCLUSIONS

This large single-center surgical pulmonary vein stenosis experience demonstrates encouraging midterm results. A new anatomically focused repair strategy aims to alleviate pulmonary vein angulation to minimize turbulence and shows promising early outcomes. Continued follow-up is required to understand longer-term outcomes for this surgical approach.

Pulmonary Vein Stenosis-Evolving Surgical Management of a Challenging Disease

Pulmonary vein stenosis (PVS) is an extremely challenging clinical problem in congenital heart disease. It has traditionally required multimodal therapy given its complex underlying pathophysiology. As with other modalities, surgical therapy has undergone tremendous evolution since the 1950s. These evolving strategies have been based upon an improved understanding of the substrates that cause PVS and recurrent vein obstruction. More recent anatomic-based surgical strategies have focused on the pulmonary vein course, and how adjacent mediastinal structures can create a fulcrum effect on the pulmonary veins as they pass from the lung parenchyma to the left atrium. The consequent angulation of pulmonary veins creates altered wall shear stress and likely serves as a nidus for recurrent PVS. Encouraging early results suggest that eliminating pulmonary vein angulation and shortening/straightening the pulmonary vein course may prove effective in surgically managing PVS.

Primary pulmonary vein stenosis during infancy: state of the art review

Primary pulmonary vein stenosis (PPVS) is an emerging problem among infants. In contrast to acquired disease, PPVS is the development of stenosis in the absence of preceding intervention. While optimal care approaches remain poorly characterized, over the past decade, understanding of potential pathophysiological mechanisms and development of novel therapeutic strategies are increasing. A multidisciplinary team of health care providers was assembled to review the available evidence and provide a common framework for the diagnosis, management, and treatment of PPVS during infancy. To address knowledge gaps, institutional and multi-institutional approaches must be employed to generate knowledge specific to ex-premature infants with PPVS. Within individual institutions, creation of a team comprised of dedicated health care providers from diverse backgrounds is critical to accelerate clinical learning and provide care for infants with PPVS. Multi-institutional collaborations, such as the PVS Network, provide the infrastructure and statistical power to advance knowledge for this rare disease.

Computed tomography-based surgical strategy for total anomalous pulmonary venous connection

OBJECTIVES

We used computed tomographic angiography (CTA)-based surgical planning to clarify the anatomical indications of sutureless repair technique for total anomalous pulmonary venous connection. The mid-term impact of the current surgical strategies was evaluated.

METHODS

One hundred twelve patients underwent repair for total anomalous pulmonary venous connection. The study period was divided into era 1 (1996-2010, n = 56) and era 2 (2011-2018, n = 56). Patients with single ventricular heart (SVH) were included. In era 2, the indications for primary sutureless repair and branch pulmonary vein incision were based on CTA findings.

RESULTS

For patients with biventricular heart, the 5-year survival was 69% and 97% in eras 1 and 2, respectively (P = 0.0024). For patients with SVH, the 5-year survival was 21% and 70% in eras 1 and 2, respectively (P = 0.0007). During the follow-up period, the evidence of post-repair pulmonary vein stenosis (PVS) was observed in 12 patients with biventricular heart [era 1, 8 patients (23%); era 2, 4 patients (13%)], and 14 patients with SVH [era 1, 6 patients (60%); era 2, 8 patients (36%)]. Using multivariable analysis, preoperative CTA was associated with improved survival in both biventricular heart and SVH and associated with post-repair PVS-free survival in SVH. Since 2011, 12 patients with post-repair PVS underwent multiple reintervention with 1 recorded death (5-year survival: 88%).

CONCLUSIONS

CTA-based surgical strategy for total anomalous pulmonary venous connection provided significant survival benefit. Although post-repair PVS could occur in era 2, aggressive reintervention appeared to be associated with improved survival and vein patency.

Pulmonary Vein Stenosis: Incremental Knowledge Gains to Improve Outcomes

Pulmonary vein stenosis remains a considerable clinical challenge, with high mortality still present in children with progressive disease. In this review, we discuss the clinical spectrum of pulmonary vein stenosis and what is known about the etiology and potential modifying and contributing factors in progressive pulmonary vein stenosis.

Effectiveness of posterior aortopexy for the left pulmonary vein obstruction between the left atrium and the descending aorta

BACKGROUND

Left pulmonary vein (PV) obstruction can occur due to compression between the left atrium (LA) and the descending aorta (DA). One of the effective solutions for this problem is posterior aortopexy. In this study, we have reported five cases of posterior aortopexy to relieve left PV obstruction between the LA and the DA.

METHODS

Since August 2012, five patients have undergone posterior aortopexy for compression of the left PV between the LA and the DA. The median age and weight of the patients at the time of operation were 5.5 months (range, 1-131 months) and 5.2 kg (range, 4.2-29.5 kg), respectively. The left PV obstruction was initially diagnosed on echocardiography in four patients and computed tomography angiography in one patient. The median peak pressure gradient across the obstructed left PV was 7.3 mmHg (range, 4-20 mmHg). Concomitant procedures were ventricular septal defect closure in one patient and patent ductus arteriosus ligation in one patient.

RESULTS

There was no PV obstruction on echocardiography in any of the patients after the operation except in the case of one patient who had diffuse pulmonary vein stenosis. The median follow-up duration was 34 months (range, 14-89 months), and during follow-up no incidence of the left PV obstruction was observed in any of the surviving patients.

CONCLUSIONS

The posterior aortopexy technique could be a good surgical option for the left PV obstruction caused by compression between the LA and the anteriorly positioned DA.

Fontan-associated liver disease and total cavopulmonary anatomical flow effectors

OBJECTIVE

We investigated a relationship between a composite index comprised of Fontan-circuit anatomical features and hepatic fibrosis scores from biopsy.

METHODS

We identified living extracardiac Fontan patients, ≥7 years old and ≥5 but <20 years postoperative, that underwent cardiac catheterization and transvenous liver biopsy between March 2012 and September 2020. We divided patients into anatomical groups and applied a risk score to each patient. We compared average anatomical risk scores with average hepatic total fibrosis scores by group.

RESULTS

We identified 111 patients that met inclusion criteria. After excluding four patients, we assigned 107 to one of 12 anatomical variant groups (n ≥ 3). For the 107, the average age at liver biopsy was 14 ± 6 years old. Of the 107, 105 (98%) were New York Heart Association Class 1. We found average anatomical risk scores by group correlated with average total fibrosis scores by group (R = 0.8; p = .005). An average Fontan duration to biopsy of 10 ± 1 years was similar for all 12 anatomical groups. We found no other clinical variables, laboratory, or hemodynamic values that trended with anatomical risk scores or hepatic total fibrosis scores.

CONCLUSIONS

In a cohort of relatively young, stable extracardiac Fontan patients, average composite anatomical risk scores strongly correlated with average hepatic total fibrosis scores by anatomical group. These findings suggest that some anatomical variants in extracardiac Fontan patients are associated with higher Fontan-associated liver disease (FALD)-related hepatic total fibrosis scores than others, despite similar Fontan durations.

Correlation of Intravascular Ultrasound with Histology in Pediatric Pulmonary Vein Stenosis

Preliminary intravascular ultrasound (IVUS) images of suspected pediatric intraluminal pulmonary vein stenosis (PVS) demonstrate wall thickening. It is unclear how the IVUS-delineated constituents of wall thickening correlate with the histology. We analyzed six postmortem formalin-fixed heart/lung specimens and four live patients with PVS as well as control pulmonary veins using IVUS and light microscopic examination. In PVS veins, IVUS demonstrated wall thickening with up to two layers of variable echogenicity, often with indistinct borders. Histologically, the veins showed fibroblastic proliferation with areas rich in myxoid matrix as well as areas with abundant collagen and elastic fibers. Discrete vein layers were obscured by scarring and elastic degeneration. A lower reflective periluminal layer by IVUS corresponded with hyperplasia of myofibroblast-like cells in abundant myxoid matrix. The hyper-reflective layer by IVUS extended to the outer edge of the vessel and corresponded to a less myxoid area with more collagen, smooth muscle and elastic fibers. The outer less reflective edge of the IVUS image correlated with a gradual transition into adventitia. Normal veins had a thin wall, correlating with histologically normal cellular and extracellular components, without intimal proliferation. IVUS may provide further understanding of the anatomy and mechanisms of pediatric pulmonary vein obstruction.

Impact of intrapulmonary-artery septation to pulmonary vein obstruction for two-lung Fontan

OBJECTIVES

Patients with unbalanced pulmonary artery (PA) growth and decreased unilateral pulmonary circulation are considered unsuitable candidates for the Fontan procedure. Following our previous study on the utility of intrapulmonary-artery septation for patients with PA hypoplasia, we investigated its use in patients with pulmonary venous obstruction (PVO).

METHODS

We recruited 42 patients who underwent intrapulmonary-artery septation for unilateral PA hypoplasia and/or PVO between 1998 and 2018 and classified them into no PVO or PVO group. We analysed overall survival, success of the Fontan procedure and data from catheterization and echocardiography. In PVO, we evaluated the functional lung area before the Fontan procedure and the relevance of this parameter to operative outcomes.

RESULTS

The PVO and no-PVO group included 24 and 18 patients, respectively. One patient in the no-PVO and 6 patients in the PVO group died during follow-up; this difference was statistically significant (log-rank P = 0.040). In the no-PVO group, 15 (83%) patients achieved two-lung Fontan circulation. In the PVO group, 12 (50%) patients achieved two-lung Fontan circulation. Multivariate analysis revealed that functional lung area and shunt size [significantly larger in patients with functional lung area ≥50% in affected lung (P = 0.040)] were significant factors for successful two-lung Fontan procedure (P = 0.030).

CONCLUSIONS

Intrapulmonary-artery septation may contribute to increase functional lung area after PVO release to establish two-lung Fontan circulation in patients with PVO who have unbalanced PA growth and/or decreased unilateral pulmonary circulation.

Maldistribution of pulmonary blood flow in patients after the Fontan operation is associated with worse exercise capacity

BACKGROUND

Maldistribution of pulmonary artery blood flow (MPBF) is a potential complication in patients who have undergone single ventricle palliation culminating in the Fontan procedure. Cardiovascular magnetic resonance (CMR) is the best modality that can evaluate MPBF in this population. The purpose of this study is to identify the prevalence and associations of MPBF and to determine the impact of MPBF on exercise capacity after the Fontan operation.

METHODS

This retrospective single-center study included all patients after Fontan operation who had maximal cardiopulmonary exercise test (CPET) and CMR with flow measurements of the branch pulmonary arteries. MPBF was defined as > 20% difference in branch pulmonary artery flow. Exercise capacity was measured as percent of predicted oxygen consumption at peak exercise (% predicted VO2). Linear and logistic regression models were used to determine univariate and multivariable predictors of exercise capacity and correlates of MPBF, respectively.

RESULTS

A total of 147 patients who had CMR between 1999 and 2017 were included (median age at CMR 21.8 years [interquartile range (IQR) 16.5-30.6]) and the median time between CMR and CPET was 2.8 months [IQR 0-13.8]. Fifty-three patients (36%) had MPBF (95% CI 29-45%). The mean % predicted VO2 was 63 ± 16%. Patients with MPBF had lower mean % predicted VO2 compared to patients without MPBF (60 ± 14% versus 65 ± 16%, p = 0.04). On multivariable analysis, a lower % predicted VO2 was independently associated with longer time since Fontan, higher ventricular mass-to-volume ratio, and MPBF. On multivariable analysis, only compression of the branch pulmonary arteries by the ascending aorta or aortic root was associated with MPBF (OR 6.5, 95% CI 5.6-7.4, p < 0.001).

CONCLUSION

In patients after the Fontan operation, MPBF is common and is independently associated with lower exercise capacity. MPBF was most likely to be caused by pulmonary artery compression by the aortic root or the ascending aorta. This study identifies MPBF as an important risk factor and as a potential target for therapeutic interventions in this fragile patient population.