Pulmonary vein and atrial wall pathology in human total anomalous pulmonary venous connection

Supracardiac total anomalous pulmonary venous connection type Ib: Morphology and outcomes

BACKGROUND

Supracardiac total anomalous pulmonary venous connection is the most common subtype of total anomalous pulmonary venous connection. We aimed to describe the morphological spectrum of supracardiac total anomalous pulmonary venous connection and to identify risk factors for death and postoperative pulmonary venous obstruction.

METHODS

From February 2009 to June 2019, 241 patients diagnosed with supracardiac-Ia (left-sided vertical vein, n = 185) or supracardiac-Ib (right-sided connection directly to superior vena cava, n = 56) total anomalous pulmonary venous connection underwent initial surgical repair at our institute. Cases with functionally univentricular circulations or atrial isomerism were excluded. Patients' postoperative survival was described by Kaplan-Meier curves. Cox proportional hazards models and competing risk regression models were used to identify clinical risk factors for death and postoperative pulmonary venous obstruction.

RESULTS

There were 8 early deaths and 4 late deaths. The overall survivals at 30 days, 1 year, and 10 years were 97.1%, 94.8%, and 94.8%, respectively, in the supracardiac-Ia group (2.7%, 5/185) (hazard ratio, 4.8; P = .003). Five patients required reoperation for pulmonary venous obstruction, including 2 patients who required reintervention for superior vena cava syndromes (all in the supracardiac-Ib group). One patient required superior vena cava balloon dilation for superior vena cava syndromes. Multivariable analysis showed that the supracardiac-Ib group (12.5%, 7/56) had a significantly higher mortality rate than the supracardiac-Ia group (adjusted hazard ratio, 8.5, P = .008). Surgical weight less than 2.5 kg (adjusted hazard ratio, 10.8, P = .023), longer duration of cardiopulmonary bypass (adjusted hazard ratio, 1.15 per 10 minutes, P = .012), and supracardiac-Ib subtype (adjusted hazard ratio, 4.7, P = .037) were independent risk factors associated with death. The supracardiac-Ib subtype (adjusted hazard ratio, 4.8, P = .003) was an incremental risk factor associated with postoperative pulmonary venous obstruction.

CONCLUSIONS

Morphological features of supracardiac total anomalous pulmonary venous connection, especially the supracardiac-Ib subtype, were risk factors associated with postoperative pulmonary venous obstruction and survival. Patients with unique anatomic subtypes might require more individualized surgical planning.

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.

How Cardiac Embryology Translates into Clinical Arrhythmias

The electrophysiological signatures of the myocardium in cardiac structures, such as the atrioventricular node, pulmonary veins or the right ventricular outflow tract, are established during development by the spatial and temporal expression of transcription factors that guide expression of specific ion channels. Genome-wide association studies have shown that small variations in genetic regions are key to the expression of these transcription factors and thereby modulate the electrical function of the heart. Moreover, mutations in these factors are found in arrhythmogenic pathologies such as congenital atrioventricular block, as well as in specific forms of atrial fibrillation and ventricular tachycardia. In this review, we discuss the developmental origin of distinct electrophysiological structures in the heart and their involvement in cardiac arrhythmias.

Quantified growth of the human embryonic heart

The size and growth patterns of the components of the human embryonic heart have remained largely undefined. To provide these data, three-dimensional heart models were generated from immunohistochemically stained sections of ten human embryonic hearts ranging from Carnegie stage 10 to 23. Fifty-eight key structures were annotated and volumetrically assessed. Sizes of the septal foramina and atrioventricular canal opening were also measured. The heart grows exponentially throughout embryonic development. There was consistently less left than right atrial myocardium, and less right than left ventricular myocardium. We observed a later onset of trabeculation in the left atrium compared to the right. Morphometry showed that the rightward expansion of the atrioventricular canal starts in week 5. The septal foramina are less than 0.1 mm² and are, therefore, much smaller than postnatal septal defects. This chronological, graphical atlas of the growth patterns of cardiac components in the human embryo provides quantified references for normal heart development. Thereby, this atlas may support early detection of cardiac malformations in the foetus.This article has an associated First Person interview with the first author of the paper.

Peculiarities of Histological Structure of Pulmonary Veins in Patients with Total Anomalous Pulmonary Venous Drainage as Morphological Substrates Relating to Formation of Postoperative Pulmonary Venous Obstruction

The histological and immunohistochemical methods were employed to examine the peculiarities of histological structure of pulmonary veins and left atrium of the heart in norm and in various types of total anomalous drainage of pulmonary veins. In contrast to normal pulmonary vein covered with external multiple muscle layers (myocardial sleeve), such sleeve is absent in veins that have no connection with the left atrium irrespective of the type of the defect. In patients with total anomalous pulmonary venous drainage, the structure of left atrium was heterogeneous featuring either the presence or absence of inner angiomural lining in this atrium. The structural peculiarities are important for insight into etiology of the development of postoperative pulmonary venous obstruction in patients with total anomalous pulmonary venous drainage.

Progression of vascular remodeling in pulmonary vein obstruction

OBJECTIVES

Pulmonary vein obstruction (PVO) frequently occurs after repair of total anomalous pulmonary vein connection with progression of intimal hyperplasia from the anastomotic site toward upstream pulmonary veins (PVs). However, the understanding of mechanism in PVO progression is constrained by lack of data derived from a physiological model of the disease, and no prophylaxis has been established. We developed a new PVO animal model, investigated the mechanisms of PVO progression, and examined a new prophylactic strategy.

METHODS

We developed a chronic PVO model using infant domestic pigs by cutting and resuturing the left lower PV followed by weekly hemodynamic parameter measurement and angiographic assessment of the anastomosed PV. Subsequently, we tested a novel therapeutic strategy with external application of rapamycin-eluting film to the anastomotic site.

RESULTS

We found the pig PVO model mimicked human PVO hemodynamically and histopathologically. This model exhibited increased expression levels of Ki-67 and phospho-mammalian target of rapamycin in smooth muscle-like cells at the anastomotic neointima. In addition, contractile to synthetic phenotypic transition; that is, dedifferentiation of smooth muscle cells and mammalian target of rapamycin pathway activation in the neointima of upstream PVs were observed. Rapamycin-eluting films externally applied around the anastomotic site inhibited the activation of mammalian target of rapamycin in the smooth muscle-like cells of neointima, and delayed PV anastomotic stenosis.

CONCLUSIONS

We demonstrate the evidence on dedifferentiation of smooth muscle-like cells and mammalian target of rapamycin pathway activation in the pathogenesis of PVO progression. Delivery of rapamycin to the anastomotic site from the external side delayed PV anastomotic stenosis, implicating a new therapeutic strategy to prevent PVO progression.

Research Progress in Pathogenesis of Total Anomalous Pulmonary Venous Connection

Congenital heart defect (CHD) is one of the most common birth defects and the leading course of infant mortality. Total anomalous pulmonary venous connection (TAPVC) is a rare type of cyanotic which accounting for approximately 1-3% of congenital heart disease cases. Based on where the anomalous veins drain, TAPVC can be divided into four subtypes: supracardiac, cardiac, infracardiac, and mixed. In TAPVC, all pulmonary veins fail to link to the left atrium correctly but make abnormal connections to the right atrium or systemic venous system. The mortality of TAPVC patients without proper intervention is nearly 80% in the first year of life and 50% of them died within 3 months after birth. However, the pathogenesis and mechanism of TAPVC remains elusive. In this chapter, we systematically review the epidemiology, anatomy, and pathophysiology of TAPVC and give an overview of the research progress of TAPVC pathogenesis.

Surgical ductal stent implantation in total anomalous pulmonary venous connection to vena porta with right pulmonary sequestration in a mature newborn

In many cases of total anomalous pulmonary venous connection (TAPVC), the four pulmonary veins (PV) join together behind the left atrium, where they form a collector. This collector can drain into the right atrium directly through the innominate vein into the superior vena cava (SVC), into the coronary sinus (CS), or through the diaphragm to the venous structures of the abdomen. In our case, a mature newborn had TAPVC draining into the vena porta along with severe pulmonary hypertension. Additionally, there were right pulmonary sequestration, dextrocardia, transposition of the great arteries, severe pulmonary stenosis, and single ventricular pathology in echocardiographic examination. Clinical signs manifested in the first 7 days of life. Diagnostic tools used were echocardiography and angiography. A ductal stent was surgically implanted into the ductus arteriosus by angiography. TAPVC was found to be nonobstructive. Therefore, we would like to emphasize the rareness and hardness to perform the surgical ductal implant technique in our particular case of TAPVC with pulmonary sequestration draining into the vena porta. The prognosis in TAPVC is poor and related mainly to the existence of pulmonary venous obstruction.

Outcomes of Reinterventions for Children with Postoperative Pulmonary Venous Restenosis

This report aims to summarize and evaluate the efficacy and experience of reintervention for children with postoperative pulmonary venous restenosis. Clinical data from 61 patients with postoperative pulmonary venous restenosis who underwent reintervention at Shanghai Children's Medical Center (SCMC) from September 2009 to June 2018 were retrospectively analyzed. The patients comprised 38 boys and 23 girls, with a mean age of 15.4 ± 12.6 months (2-83 months) and a mean weight of 8.1 ± 3.4 kg (3.7-18.5 kg). The mean pulmonary venous velocity was 2.31 ± 0.47 m/s (1.86-3.22 m/s). Primary disease included 48 cases of total anomalous pulmonary venous drainage, nine cases of partial anomalous pulmonary venous drainage, and four cases of primary pulmonary venous stenosis. The reintervention procedures included 34 cases using the sutureless technique, ten cases using bovine pericardium enlargement, three cases using blunt enlargement, four cases of balloon dilatation, one case using stent implantation and nine cases involving more than two surgical methods. The early postoperative pulmonary venous velocity was 1.16 ± 0.20 m/s. There were five in-hospital deaths, resulting in a mortality rate of 8.2%. Fifty-six survivors were followed for 52.8 ± 46.5 months (6-103 months) with no delayed deaths. Echocardiography showed pulmonary venous anastomosis and diameter growth after reintervention, exhibiting a mean growth speed of 0.026 ± 0.013 cm/month (p < 0.05) and a mean velocity of 1.24 ± 0.26 m/s; five patients experienced varying degrees of pulmonary venous obstruction (> 1.6 m/s), but did not require reoperation. Postoperative pulmonary venous restenosis is a common complication after surgery for pulmonary venous malformations. Reintervention should be performed in the early period of pulmonary venous obstruction. Growth of pulmonary venous anastomoses was observed after performing the sutureless technique, bovine pericardium enlargement and blunt enlargement. Although balloon dilatation has a good effect in the early postoperative period, its restenosis rate is high, and strict mid- to long-term follow-up is needed.

Transcatheter therapy of partial anomalous pulmonary venous connection with dual drainage and coarctation of the aorta in a single patient

A 12-year-old boy was found to have aortic coarctation and a partial anomalous pulmonary venous connection. Historically, multiple cardiac pathologies, such as in the present case, required a surgical approach. We describe transcatheter treatment of the coarctation with a stent and occlusion of the partial anomalous pulmonary venous connection with an Amplatzer vascular plug in a single patient without complications.

Duplication and Deletion of 22q11 Associated with Anomalous Pulmonary Venous Connection

Anomalous pulmonary venous connection (APVC) is an uncommon congenital anomaly in which pulmonary venous blood flows directly into the right side of the heart or into the systemic veins. To identify whether there is any association between 22q11 CNVs and APVC, we analyzed the clinical data of 86 APVC patients and then studied the CNVs of 22q11 in 86 sporadic APVC patients by multiplex ligation-dependent probe amplification. The results showed that two patients carried the CNVs of 22q11, one patient had the deletion of 22q11 and the other had the duplication of 22q11. The incidence was significantly higher than that in the normal population (P < 0.01) that suggests a possible etiologic association between the duplication or deletion of 22q11 and the APVC in our patients.

The Role of Superior Vena Cava Isolation in the Management of Atrial Fibrillation

The superior vena cava (SVC) has been identified as one of the most common sources of non-pulmonary vein triggers for atrial fibrillation (AF). SVC isolation has been shown to improve long-term maintenance of normal sinus rhythm in patients with paroxysmal AF. However, ablation at the SVC is associated with risks of phrenic nerve injury, sinus node dysfunction, and SVC stenosis. The use of electroanatomical mapping, intracardiac echocardiography, compound motor action potentials, and segmental (rather than circumferential) ablation are all strategies to reduce complications. Given these risks, SVC isolation is most effective as an adjunct to pulmonary vein isolation for patients with paroxysmal AF who have been found to have an arrhythmogenic SVC.

Stenting of vertical vein in an infant with obstructed supracardiac total anomalous pulmonary venous drainage

A 1.7 kg infant with obstructed supracardiac total anomalous pulmonary venous drainage (TAPVD) presented with severe pulmonary hypertension secondary to vertical vein obstruction. The child, in addition, had a large omphalocele that was being managed conservatively. The combination of low weight, unoperated omphalocele, and severe pulmonary hypertension made corrective cardiac surgery very high-risk. Therefore, transcatheter stenting of the stenotic vertical vein, as a bridge to corrective surgery was carried out. The procedure was carried out through the right internal jugular vein (RIJ). The stenotic segment of the vertical vein was stented using a coronary stent. After procedure, the child was discharged well to the referred hospital for weight gain and spontaneous epithelialization of the omphalocele. Stenting of the vertical vein through the internal jugular vein can be considered in very small neonates as a bridge to repair obstructed supracardiac total anomalous venous drainage.

[Contribution of 3D-ultrasound in the heterotaxy syndromes: about four cases and review of the literature]

The position or location of the organs and vessels is usually classified into three types: situs solitus, situs inversus, and situs ambigus. Situs solitus is the usual arrangement of organs and vessels within the body. Only 0.6 to 0.8% of patients with situs solitus and levocardia have associated congenital heart diseases. Situs inversus refers to an anatomic arrangement that is the mirror image of situs solitus. The incidence of congenital heart disease is increased to 3 to 5% in the patients with situs inversus. The patients with heterotaxy have congenital heart disease in high incidence, ranging from 50 to nearly 100%. We present four cases diagnosed in our department in a period of 18 months. With these four cases and a review in the literature, we explore the definitions and characteristics of heterotaxy syndromes and we study the role of 3D ultrasound.

Dysregulation of the PDGFRA gene causes inflow tract anomalies including TAPVR: integrating evidence from human genetics and model organisms

Total anomalous pulmonary venous return (TAPVR) is a congenital heart defect inherited via complex genetic and/or environmental factors. We report detailed mapping in extended TAPVR kindreds and mutation analysis in TAPVR patients that implicate the PDGFRA gene in the development of TAPVR. Gene expression studies in mouse and chick embryos for both the Pdgfra receptor and its ligand Pdgf-a show temporal and spatial patterns consistent with a role in pulmonary vein (PV) development. We used an in ovo function blocking assay in chick and a conditional knockout approach in mouse to knock down Pdgfra expression in the developing venous pole during the period of PV formation. We observed that loss of PDGFRA function in both organisms causes TAPVR with low penetrance (approximately 7%) reminiscent of that observed in our human TAPVR kindreds. Intermediate inflow tract anomalies occurred in a higher percentage of embryos (approximately 30%), suggesting that TAPVR occurs at one end of a spectrum of defects. We show that the anomalous pulmonary venous connection seen in chick and mouse is highly similar to TAPVR discovered in an abnormal early stage embryo from the Kyoto human embryo collection. Whereas the embryology of the normal venous pole and PV is becoming understood, little is known about the embryogenesis or molecular pathogenesis of TAPVR. These models of TAPVR provide important insight into the pathogenesis of PV defects. Taken together, these data from human genetics and animal models support a role for PDGF-signaling in normal PV development, and in the pathogenesis of TAPVR.