New approach to the surgical management of pulmonary arteriovenous malformations after cavopulmonary anastomosis

A catheter-based interventional strategy redirects hepatic vein flows after Fontan procedure in left isomerism to treat severe hypoxemia

Pulmonary arteriovenous malformations after the Kawashima procedure causing severe hypoxemia are treated by Fontan surgery that redirects hepatic venous blood to the pulmonary circulation. Alignment of the hepatic venous conduit toward both pulmonary arteries is crucial for their regression. Persistent hypoxemia due to nonregressed malformations in one lung often warrants a repeat surgery to redirect hepatic venous flows. Catheter-based redirection of Fontan flows is not commonly performed as metallic stents and devices may predispose to thrombus formation in the circuit. This report highlights a patient with persistent arteriovenous malformations in the left lung leading to severe disabling hypoxemia that was managed in the catheterization laboratory with an innovative strategy to redirect Fontan flows toward the affected left lung.

Hepatoazygos venous shunt for Fontan completion after Kawashima operation

Fontan completion after prior Kawashima repair for single ventricle with interruption of the inferior vena cava can be accomplished by various methods. We describe a patient who underwent the connection of hepatic to hemiazygos vein that we believe would be superior to the conventional cavopulmonary connection in our patient.

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.

Urgent hepatic to azygous vein connection for thrombosis of hepatic vein to pulmonary artery conduit

We report on an emergent use of hepatic-to-azygous vein connection using a 10-mm polytetrafluoroethylene graft in a 6-year-old girl who developed acute thrombosis of an extracardiac graft conduit from the hepatic veins to the pulmonary arteries. She had left atrial isomerism, interrupted inferior vena cava with azygous continuation, and had undergone surgical creation of bilateral superior cavopulmonary connections 5 years earlier. The emergency procedure to create hepatic-to-azygous connection resulted in successful salvage of the patient who was subsequently able to maintain stable oxygen saturations and experienced rapid regression of hepatic congestion and pleural effusions. Six months following the procedure, oxygen saturation was above 90%. Repeated echocardiography and computed tomography angiography showed patency of the hepatic-to-azygous connection.

Normal and abnormal pulmonary arteriovenous shunting: occurrence and mechanisms

Severe cyanosis due to pulmonary arteriovenous fistulas occurs often after a bidirectional superior cavopulmonary anastomosis (Glenn operation) and also in some congenital anomalies in which hepatic venous blood bypasses the lungs in the first passage. Relocation of hepatic flow into the lungs usually causes these fistulas to disappear. Similar pulmonary arteriovenous fistulas are observed in hereditary haemorrhagic telangiectasia, and in liver disease (hepatopulmonary syndrome). There is no convincing identification yet of a responsible hepatic factor that produces these lesions. Candidates for such a factor are reviewed, and the possibility of angiotensin or bradykinin contributing to the fistulas is discussed.

The Fontan Connections: Past, Present, and Future

The Fontan procedure is now considered the final common pathway for patients with anatomical or functional single ventricle. These patients initially have their systemic and pulmonary circulations in parallel, supported by one functional ventricular chamber. The ultimate goal with this procedure is to separate the two circulations, to prevent mixing of venous and arterial blood, and to provide adequate tissue oxygenation. The objective of this article is to review the Fontan procedure with its various modifications and refinements since its introduction to clinical practice in 1971, by Fontan and Baudet.

Reconstruction of cavopulmonary pathway for the patient with persistent arteriovenous malformations due to offset flow from hepatic vein

The hypoxemia caused by arteriovenous malformations after cavopulmonary shunt in patients with heterotaxy, an interrupted inferior vena cava and single ventricle physiology have been treated by incorporation of hepatic vein flow into the pulmonary circulation. However, some patients have persistent arteriovenous malformations because of offset hepatic venous flow to one pulmonary artery. Various approaches have been used to change offset flow to achieve balanced hepatic flow to the lungs in this patient population. This case report highlights the challenges that may be associated with anastomosis of the azygos vein to the inferior vena cava at the level of the diaphragm and illustrates an alternative technique to direct hepatic venous blood into an affected lung with arteriovenous malformations. The redirection of hepatic venous flow to the affected pulmonary artery resulted in resolution of symptoms within months of surgery.

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.

Pulmonary Arteriovenous Malformations in Heterotaxy Syndrome

We report a surgical approach using hepatic vein–to–azygos vein connection without cardiopulmonary bypass or deep hypothermic circulatory arrest in a patient with heterotaxy syndrome and interrupted inferior vena cava with persistence of pulmonary arteriovenous malformations (PAVMs) after previous Fontan completion. We advocate early performance of hepatic vein–to–azygos vein connection following the Kawashima operation for heterotaxy with functionally univentricular heart and interrupted inferior vena cava. We review the physiology of heterotaxy syndrome with congenital heart disease and justify our approach in the context of a review of previous surgical strategies used in this patient population.

CT findings in unilateral hepatopulmonary syndrome after the Fontan operation

BACKGROUND

Patients with complex congenital heart defects palliated by connecting the systemic veins directly to the pulmonary circulation are known to develop hepatopulmonary syndrome (HPS). Although rare, HPS can develop following the Fontan operation.

OBJECTIVE

To present and analyse the CT findings of HPS in patients with a Fontan circulation.

MATERIALS AND METHODS

From May to December 2005, six patients with HPS following the completion of a Fontan circulation were evaluated. CT findings were reviewed and were compared with angiographic findings.

RESULTS

All six patients showed unilateral involvement. All patients except one had inferior vena cava (IVC) interruption with azygos continuation. CT scans showed abnormal vascular dilatation in one lung, and properly demonstrated the anatomy causing the hepatic venous blood to flow preferentially into one lung. These CT findings correlated well with the angiography findings.

CONCLUSION

HPS that develops after the Fontan procedure is typically unilateral and is often associated with IVC interruption and azygos or hemiazygos continuation. CT demonstrates dilatation of pulmonary vessels in the affected lung and may be able to demonstrate the underlying anatomical cause for the predilection of hepatic venous flow to the contralateral lung.

Off-pump connection of the hepatic to the azygos vein through a lateral thoracotomy for relief of arterio-venous fistulas after a Kawashima procedure

OBJECTIVE

To connect the hepatic veins to the azygos venous system through a lateral thoracotomy, and without the use of extracorporeal circulation, so as to relieve arteriovenous fistulas after a previous Kawashima operation.

METHODS

Description of the operative technique by which the hepatic veins are anastomosed to the hepatic venous system.

RESULTS

The surgical approach was successfully applied in 3 patients, all of whom showed an excellent rise of saturations of oxygen after redirection of the hepatic venous blood.

CONCLUSION

The operative method presented is an elegant means of redirecting the hepatic venous blood to the pulmonary circulation without the disadvantages of extracorporeal circulation and resternotomy.

Redirection of hepatic drainage for treatment of pulmonary arteriovenous malformations following the Fontan procedure

The development of unilateral pulmonary arteriovenous malformations in patients after total cavopulmonary connection with an extracardiac conduit has been reported. Unequal distribution of hepatic venous flow to the lung is theorized to be the causative factor. We report the surgical management of pulmonary arteriovenous malformations in a patient with heterotaxy syndrome, single ventricle, and interrupted inferior vena cava. The patient had previously undergone a total cavopulmonary connection with an extracardiac conduit draining hepatic venous flow to the right branch pulmonary artery. In the subsequent operation, we redirected the extracardiac conduit to the innominate vein. This operation provided the affected lung with hepatic venous blood without exposing the patient to the morbidity associated with cardiopulmonary bypass.

Management of systemic venous anomalies in the pediatric cardiovascular surgical patient

Systemic venous anomalies are rare and heterogeneous entities. Although these anomalies are rare in the general population, they occur more frequently in the subpopulation with congenital heart disease. In and of themselves, most of these lesions have no physiologic significance. However, in the setting of congenital heart disease these lesions may significantly alter surgical treatment. This review is dedicated to these lesions.

Pulmonary Arteriovenous Malformations in Children After the Kawashima Operation

BACKGROUND

Pulmonary arteriovenous malformations are a major cause of progressive late cyanosis in patients treated with cavopulmonary anastomoses. Previous experience suggests that exclusion of the hepatic venous effluent from the pulmonary circulation may cause the development of pulmonary arteriovenous malformations after the Kawashima operation in children with interrupted inferior vena cava with azygous continuation.

METHODS

From January 1990 to November 2004, 21 children (median age, 2 years) with heterotaxy syndrome and interrupted inferior vena cava with azygous continuation underwent Kawashima operation. The average preoperative arterial oxygen saturation was 76% +/- 7% (range, 64% to 90%).

RESULTS

Follow-up was complete in all survivors except 1 at a median duration of 4.5 years. Pulmonary arteriovenous malformations were diagnosed at a median of 5 years after Kawashima operation in 11 patients (58%). Completion Fontan operation has been performed in 15 (79%). Five children who underwent a completion Fontan procedure 1 to 1.5 years after Kawashima operation did not have pulmonary arteriovenous malformations. There were 2 late deaths due to chronic congestive heart failure 4 months and 7 years after Kawashima operation. Overall survival at 10 years is 90%. Univariate and multivariate analysis demonstrated presence of bilateral superior vena cavae (p = 0.002) and interval longer than 2 years between Kawashima operation and completion Fontan operation (p = 0.04) as predictors of developing pulmonary arteriovenous malformations.

CONCLUSIONS

In most patients with heterotaxy and interrupted inferior vena cava with azygous continuation, clinical evidence of pulmonary arteriovenous malformations will develop after Kawashima operation if they are followed up long enough. Early redirection of the hepatic venous effluent to the pulmonary arterial circulation may prevent or lead to regression of pulmonary arteriovenous malformations, with low mortality and morbidity.

The biological "scrabble" of pulmonary arteriovenous malformations: considerations in the setting of cavopulmonary surgery

Pulmonary arteriovenous fistulas are vascular malformations, which, by virtue of producing abnormal vascular connections proximal to the units of gas exchange, result in intrapulmonary right-to-left shunting. These malformations or fistulas reflect at least in part disordered angiogenesis, and less commonly recruitment and dilation of pre-existing vascular channels. Pulmonary arteriovenous fistulas occur in a number of diverse clinical settings. Such fistulas are a well-established feature of the Weber-Osler-Rendu complex, or hereditary haemorrhagic telangiectasia, an autosomal dominant vascular dysplasia characterized by mucocutaneous telangiectasis, epistaxis, gastrointestinal haemorrhage, and arteriovenous malformations in the lung, brain, liver and elsewhere. They are also seen in the patient with acute or chronic liver disease, disease that is usually but not invariably severe, or those with non-cirrhotic portal hypertension. They may occur as congenital malformations, single or diffuse, large or small in isolation, and when large or extensive enough may result in hypoxaemia, clinical cyanosis, and heart failure. Cerebral vascular accidents are also a well-known complication of this disorder. An extensive literature has accumulated with regard to the pulmonary arteriovenous fistulas seen in the setting of the Weber-Osler-Rendu complex, and there is considerable information on the genetics, basic biology, clinical findings, complications and therapeutic interventions of these malformations in the setting of this syndrome. These issues, however, are not the primary considerations of this review, although some aspects of this fascinating disorder will be discussed later. Rather the focus will be on pulmonary arteriovenous malformations that develop in the setting of cavopulmonary surgery, and their relationship to the pulmonary arteriovenous fistulas occurring in the hepatopulmonary syndrome. The complex tapestry of these overlapping and intersecting clinical observations will be unfolded in the light of their chronology.