Regression of pulmonary arteriovenous malformations after transcatheter reconnection of the pulmonary arteries in patients with unidirectional Fontan

Transcatheter biventricular conversion in an adult patient with a 1.5 ventricle Glenn palliation and superior vena cava syndrome

Covered stents have a continually expanding spectrum of applications for patients with congenital heart disease. Here we report use of covered stents to successfully perform a first-in-human percutaneous biventricular conversion of a 1.5 ventricle Glenn palliation in an adult born with pulmonary atresia. This case demonstrates that in patients considered borderline for biventricular repair, surgery can potentially be modified to promote growth of underdeveloped structures and setup for transcatheter biventricular conversion.

Angiopoietin-2 predicts morbidity in adults with Fontan physiology

Morbidity in patients with single-ventricle Fontan circulation is common and includes arrhythmias, edema, and pulmonary arteriovenous malformations (PAVM) among others. We sought to identify biomarkers that may predict such complications. Twenty-five patients with Fontan physiology and 12 control patients with atrial septal defects (ASD) that underwent cardiac catheterization were included. Plasma was collected from the hepatic vein and superior vena cava and underwent protein profiling for a panel of 20 analytes involved in angiogenesis and endothelial dysfunction. Ten (40%) of Fontan patients had evidence of PAVM, eighteen (72%) had a history of arrhythmia, and five (20%) were actively in arrhythmia or had a recent arrhythmia. Angiopoietin-2 (Ang-2) was higher in Fontan patients (8,875.4 ± 3,336.9 pg/mL) versus the ASD group (1,663.6 ± 587.3 pg/mL, p < 0.0001). Ang-2 was higher in Fontan patients with active or recent arrhythmia (11,396.0 ± 3,457.7 vs 8,118.2 ± 2,795.1 pg/mL, p < 0.05). A threshold of 8,500 pg/mL gives Ang-2 a negative predictive value of 100% and positive predictive value of 42% in diagnosing recent arrhythmia. Ang-2 is elevated among adults with Fontan physiology. Ang-2 level is associated with active or recent arrhythmia, but was not found to be associated with PAVM.

Transcatheter redirection of hepatic venous blood to treat unilateral pulmonary arteriovenous malformations in a Fontan circulation by short-term total exclusion of the unaffected lung

Clinically significant unilateral pulmonary arteriovenous malformations (PAVM) can develop in patients with a Fontan circulation when there is unbalanced distribution of hepatic venous (HV) blood flow to the lungs. There are reported surgical and transcatheter techniques to treat PAVMs by rerouting HV return, with promising short-term results. We report a case of a novel, technically simple transcatheter approach to redirect HV blood flow in an adult Fontan patient with polysplenia syndrome and severe unilateral PAVMs. Our patient had a two-stage procedure, the first to redirect all HV blood flow to the affected lung with a single covered stent, and a second to confirm resolution of PAVMs and to reintroduce HV effluent to the unaffected lung. At 10-month follow-up, her oxygen saturations had increased from 75% to 93% with a marked improvement in her functional status.

First-in-Human Closed-Chest Transcatheter Superior Cavopulmonary Anastomosis

BACKGROUND

In the care of patients with congenital heart disease, percutaneous interventional treatments have supplanted many surgical approaches for simple lesions, such as atrial septal defect. By contrast, complex congenital heart defects continue to require open-heart surgery. In single-ventricle patients, a staged approach is employed, which requires multiple open-heart surgeries and significant attendant morbidity and mortality. A nonsurgical transcatheter alternative would be attractive.

OBJECTIVES

The authors sought to show the feasibility of catheter-only, closed-chest, large-vessel anastomosis (superior vena cava and pulmonary artery [PA] or bidirectional Glenn operation equivalent) in a patient.

METHODS

In preclinical testing over a decade, the authors developed the techniques and technology needed for nonsurgical crossing from a donor (superior vena cava) to a recipient (PA) vessel and endovascular stent-based anastomosis of those blood vessels. The authors undertook this transcatheter approach for an adult with untreated congenital heart disease with severe cyanosis and significant surgical risk. They rehearsed the procedure step by step using contrast-enhanced cardiac computed tomography and a patient-specific 3-dimensional printed heart model.

RESULTS

The authors describe a first-in-human, fully percutaneous superior cavopulmonary anastomosis (bidirectional Glenn operation equivalent). The patient, a 35-year-old woman, was homebound due to dyspnea and worsening cyanosis. She was diagnosed with functional single ventricle and very limited pulmonary blood flow. The heart team believed surgical palliation conferred high operative risk due to the patient's complete condition. With the percutaneous procedure, the patient recovered uneventfully and remained improved clinically after 6 months.

CONCLUSIONS

This procedure may provide a viable alternative to one of the foundational open-heart surgeries currently performed to treat single-ventricle congenital heart disease.

Hemodynamic study of TCPC using in vivo and in vitro 4D Flow MRI and numerical simulation

INTRODUCTION

Altered total cavopulmonary connection (TCPC) hemodynamics can cause long-term complications. Patient-specific anatomy hinders generalized solutions. 4D Flow MRI allows in vivo assessment, but not predictions under varying conditions and surgical approaches. Computational fluid dynamics (CFD) improves understanding and explores varying physiological conditions. This study investigated a combination of 4D Flow MRI and CFD to assess TCPC hemodynamics, accompanied with in vitro measurements as CFD validation. 4D Flow MRI was performed in extracardiac and atriopulmonary TCPC subjects. Data was processed for visualization and quantification of velocity and flow. Three-dimensional (3D) geometries were generated from angiography scans and used for CFD and a physical model construction through additive manufacturing. These models were connected to a perfusion system, circulating water through the vena cavae and exiting through the pulmonary arteries at two flow rates. Models underwent 4D Flow MRI and image processing. CFD simulated the in vitro system, applying two different inlet conditions from in vitro 4D Flow MRI measurements; no-slip was implemented at rigid walls. Velocity and flow were obtained and analyzed. The three approaches showed similar velocities, increasing proportionally with high inflow. Atriopulmonary TCPC presented higher vorticity compared to extracardiac at both inflow rates. Increased inflow balanced flow distribution in both TCPC cases. Atriopulmonary IVC flow participated in atrium recirculation, contributing to RPA outflow; at baseline, IVC flow preferentially traveled through the LPA. The combination of patient-specific in vitro and CFD allows hemodynamic parameter control, impossible in vivo. Physical models serve as CFD verification and fine-tuning tools.

Catheter approach to redirect hepatic venous return for treatment of unilateral pulmonary arteriovenous malformations after fontan

OBJECTIVES

The goal of this report is to describe a percutaneous approach to rerouting hepatic venous return in patients who developed progressive cyanosis due to unilateral pulmonary arteriovenous malformations (PAVM) after the total cavopulmonary connection (TCPC) operation.

BACKGROUND

Unilateral PAVM can develop in patients after TCPC operation when there is unequal distribution of hepatic venous return between the two lungs. This often results in progressive cyanosis and the need for surgical re-intervention. A percutaneous based approach for rerouting hepatic venous return has never been described.

METHODS

We retrospectively reviewed the clinical data on four patients who underwent percutaneous rerouting procedures. One patient with a misaligned TCPC underwent realignment of the circuit with a bare metal stent. In three patients a combination of bare metal and covered stents were needed to achieve the desired results.

RESULTS

The rerouting procedures were successful in all patients with significant improvement in oxygen saturation from a median of 75% (range 55-80%) to a median of 90% (range 84-92%) (P = 0.02). There were no recorded short term or intermediate term complications with maximum follow-up time of 43 months.

CONCLUSIONS

Percutaneous rerouting of hepatic venous flow is feasible and should be considered when a surgical approach is not possible; this strategy may serve as a viable alternative to complex operative approaches in select cases. Furthermore studies are needed to determine the long-term efficacy of this procedure.

Shunt reduction to pulmonary arteriovenous malformations using a modified covered stent

Pulmonary arteriovenous malformations in patients with congenital heart disease have been associated with interruption of hepatic venous return to the lungs. We report a novel technique to improve systemic saturation using a modified covered stent in a patient with unilateral left pulmonary arteriovenous malformations in the setting of a Fontan circulation.

Acute dyspnea in a young man with an old sternotomy

Described is a 42-year-old man with complex congenital heart disease with single-ventricle physiology who underwent a Fontan operation at 27 years of age. He presented with sudden-onset chest pain and dyspnea and was initially misdiagnosed with a pulmonary embolism. This case is described in order to highlight the challenges in the evaluation of common presentations in adults with congenital heart disease.

Late catheter interventions in hypoplastic left heart syndrome

Interventional cardiology plays a key role in the diagnosis and management of patients with functionally univentricular physiology after the various stages of surgical palliation. The interventions performed are widely variable in type, including angioplasty of stenotic vessels and implantation of stents in stenotic vessels; closure of defects such as collaterals, leaks in baffles, and fenestrations; creation of fenestration; and more. In the setting of venous hypertension associated with stenosis at the Fontan baffle, conduit, or pulmonary arteries, stent implantation is often preferred, as the aim is to eliminate completely the narrowing, given that relatively mild stenosis can have a significant detrimental hemodynamic effect in patients with functionally univentricular circulation. The procedure is highly successful. In patients who fail after Fontan procedure, creation of a fenestration is often performed, with variable technique depending on the underlying anatomic substrate. To increase chances of patency of the fenestration, implantation of a stent is often required, particularly in the setting of an extracardiac conduit. For those patients with cyanosis and favorable Fontan hemodynamics, closure of the fenestration is performed using atrial septal occluder devices with high success rate. Coils compatible with magnetic resonance imaging are used widely to treat collateral vessels, although on occasion other specific embolization tools are required, such as particles or vascular plugs. Postoperative arch obstruction is successfully managed with angioplasty at a younger age, while implantation of a stent in the aorta is reserved for older patients. Specifics of these interventional procedures as applied to the population of patients with functionally univentricular hearts are described in this manuscript.

Congenital portosystemic venous connections and other abdominal venous abnormalities in patients with polysplenia and functionally univentricular heart disease: a case series and literature review

OBJECTIVE

Published case reports suggest that congenital portosystemic venous connections (PSVC) and other abdominal venous anomalies may be relatively frequent and potentially important in patients with polysplenia syndrome. Our objective was to investigate the frequency and range of portal and other abdominal systemic venous anomalies in patients with polysplenia and inferior vena cava (IVC) interruption who underwent a cavopulmonary anastomosis procedure at our center, and to review the published literature on this topic and the potential clinical importance of such anomalies.

DESIGN

Retrospective cohort study and literature review were used.

RESULTS

Among 77 patients with heterotaxy, univentricular heart disease, and IVC interruption who underwent a bidirectional Glenn and/or modified Fontan procedure, pulmonary arteriovenous malformations were diagnosed in 33 (43%). Bilateral superior vena cavas were present in 42 patients (55%). Despite inadequate imaging in many patients, a partial PSVC, dual IVCs, and/or renal vein anomalies were detected in 15 patients (19%). A PSVC formed by a tortuous vessel running from the systemic venous system to the extrahepatic portal vein was found in six patients (8%). Abdominal venous anomalies other than PSVC were documented in 13 patients (16%), including nine (12%) with some form of duplicated IVC system, with a large azygous vein continuing to the superior vena cava and a parallel, contralateral IVC of similar or smaller size, and seven with renal vein anomalies. In patients with a partial PSVC or a duplicate IVC that connected to the atrium, the abnormal connection allowed right-to-left shunting.

CONCLUSIONS

PSVC and other abdominal venous anomalies may be clinically important but under-recognized in patients with IVC interruption and univentricular heart disease. In such patients, preoperative evaluation of the abdominal systemic venous system may be valuable. More data are necessary to determine whether there is a pathophysiologic connection between the polysplenia variant of heterotaxy, PSVC, and cavopulmonary anastomosis-associated pulmonary arteriovenous malformations.

Pulmonary hepatic flow distribution in total cavopulmonary connections: extracardiac versus intracardiac

OBJECTIVE

Pulmonary arteriovenous malformations can occur after the Fontan procedure and are believed to be associated with disproportionate pulmonary distribution of hepatic venous effluent. We studied the effect of total cavopulmonary connection geometry and the effect of increased cardiac output on distribution of inferior vena caval return to the lungs.

METHODS

Ten patients undergoing the Fontan procedure, 5 with extracardiac and 5 with intracardiac configurations of the total cavopulmonary connection, previously analyzed for power loss were processed for calculating the distribution of inferior vena caval return to the lungs (second-order accuracy). One idealized total cavopulmonary connection was similarly analyzed under parametric variation of inferior vena caval offset and cardiac output flow split.

RESULTS

Streaming of the inferior vena caval return in the idealized total cavopulmonary connection model was dependent on both inferior vena caval offset magnitude and cardiac output flow-split ratio. For patient-specific total cavopulmonary connections, preferential streaming of the inferior vena caval return was directly proportional to the cardiac output flow-split ratio in the intracardiac total cavopulmonary connections (P < .0001). Preferential streaming in extracardiac total cavopulmonary connections correlated to the inferior vena caval offset (P < .05) and did not correlate to cardiac output flow split. Enhanced mixing in intracardiac total cavopulmonary connections is speculated to explain the contrasting results. Exercising tends to reduce streaming toward the left pulmonary artery in intracardiac total cavopulmonary connections, whereas for extracardiac total cavopulmonary connections, exercising tends to equalize the streaming.

CONCLUSIONS

Extracardiac and intracardiac total cavopulmonary connections have inherently different streaming characteristics because of contrasting mixing characteristics caused by their geometric differences. Pulmonary artery diameters and inferior vena caval offsets might together determine hepatic flow streaming.

Expression of vascular endothelial growth factor is coordinately regulated by the activin-like kinase receptors 1 and 5 in endothelial cells

Expression of vascular endothelial growth factor (VEGF) is tightly regulated to achieve normal angiogenesis. The objective was to examine regulation of VEGF by the activin-like kinase receptors (ALKs) ALK1 and ALK5. Transforming growth factor beta1 (TGFbeta1) and bone morphogenetic protein-9 (BMP-9) enhanced and suppressed VEGF expression, respectively, in aortic endothelial cells, as determined by real-time polymerase chain reaction, immunoblotting, cell proliferation, and tube formation. The use of small interfering RNA revealed that TGFbeta1 stimulated VEGF expression by activating ALK5, TGFbeta type II receptor, and SMAD2, whereas BMP-9 suppressed it by activating ALK1, BMP type II receptor, and SMAD1. ALK1 signaling occurred independently of ALK5 activity. Partial ALK1 deficiency in vitro and in vivo resulted in elevated VEGF expression. In vitro, increased BMP-9 levels normalized VEGF expression in cells with partial, but not severe, ALK1 deficiency. Time course experiments revealed that an increase in ALK1 expression induced by BMP-4, an angiogenic stimulus, preceded induction of ALK5 and VEGF in control cells. In ALK1-deficient cells, however, VEGF expression occurred earlier and was abnormally high, even though ALK5 was not induced. Our results suggest that ALK1 and ALK5 are both essential for correct regulation of VEGF, and that disruption of either pathway leads to disease.

The adult with a Fontan operation

Since 1971, the Fontan operation has been performed for the repair of single-ventricle physiology. This ingenious operation commits a single ventricle to the systemic circulation and takes advantage of cardiovascular and respiratory physiology to propel deoxygenated blood to the lungs, thus minimizing right-to-left shunting and cyanosis. Initially performed as a right atrial to pulmonary artery anastomosis, the Fontan operation has gone through evolutionary steps that have resulted in progressive improvements in mortality, morbidity, and outcomes. Inclusion of the right atrium in the slow-flowing Fontan circuit results in progressive dilation and incessant arrhythmias. This spurred forth efforts to create modifications that partially or completely exclude the atrium from the Fontan circuit. The transcatheter completion of the Fontan operation has been performed in a small number of patients and we expect minimally invasive, transcatheter, and hybrid interventions to play an important role in the future management of these patients.