Late catheter interventions in hypoplastic left heart syndrome

Extra-cardiac and complex Fontan baffle fenestration using radio frequency current via surgical electrocautery

BACKGROUND

Fontan baffle punctures and creation of Fontan fenestration for cardiac catheterisation procedures remain challenging especially due to the heavy calcification of prosthetic material and complex anatomy.

OBJECTIVES

We sought to evaluate our experience using radiofrequency current via surgical electrocautery needle for Fontan baffle puncture to facilitate diagnostic, electrophysiology, and interventional procedures.

METHODS

A retrospective chart review of all Fontan patients (pts) who underwent Fontan baffle puncture using radiofrequency energy via surgical electrocautery from three centres were performed from January 2011 to July 2021.

RESULTS

A total of 19 pts underwent 22 successful Fontan baffle puncture. The median age and weight were 17 (3-36 years) and 55 (14-88) kg, respectively. The procedural indications for Fontan fenestration creation included: diagnostic study (n = 1), atrial septostomy and stenting (n = 1), electrophysiology study and ablation procedures (n = 8), Fontan baffle stenting for Fontan failure including protein-losing enteropathy (n = 7), and occlusion of veno-venous collaterals (n = 2) for cyanosis. The type of Fontan baffles included: extra-cardiac conduits (n = 12), lateral tunnel (n = 5), classic atrio-pulmonary connection (n = 1), and intra-cardiac baffle (n = 1). A Fontan baffle puncture was initially attempted using traditional method in 6 pts and Baylis radiofrequency trans-septal system in 2 pts unsuccessfully. In all pts, Fontan baffle puncture using radiofrequency energy via electrocautery needle was successful. The radiofrequency energy utilised was (10-50 W) and required 1-5 attempts for 2-5 seconds. There were no vascular or neurological complications.

CONCLUSIONS

Radiofrequency current delivery using surgical electrocautery facilitates Fontan baffle puncture in patients with complex and calcified Fontan baffles for diagnostic, interventional, and electrophysiology procedures.

Hemodynamic assessment of atrial septal defects

Atrial septal defect (ASD) is one of the most common congenital cardiac anomalies. ASD can present as an isolated lesion in an otherwise normal heart or in association with other congenital heart conditions. Regardless of the type of ASD, the direction and degree of shunting across the communication is mainly determined by the difference in compliance between the right and left ventricle. Hemodynamics in children is characterized by left-to-right shunting, dilated right heart structures and normal pulmonary artery pressures (PAP). Patients diagnosed at adult age often present with complications related to long-standing volume overload such as pulmonary artery hypertension and right and left ventricular dysfunction. Diagnostic catheterization is usually not indicated unless there is suggestion of pulmonary hypertension on echocardiography. In older patients and/or in those with ventricular dysfunction, measurement of left heart pressures during temporary balloon occlusion is recommended prior to device closure as it may not be tolerated. In ASD associated with other congenital malformations, shunting degree and direction will depend upon underlying condition. Restrictive ASD can result in significant hemodynamic compromise in neonates with conditions such as hypoplastic left heart syndrome (HLHS) and transposition of the great arteries (TGA). In most cases, hemodynamics can be estimated with echocardiography only.

State of the art of the Fontan strategy for treatment of univentricular heart disease

In patients with a functionally univentricular heart, the Fontan strategy achieves separation of the systemic and pulmonary circulation and reduction of ventricular volume overload. Contemporary modifications of surgical techniques have significantly improved survival. However, the resulting Fontan physiology is associated with high morbidity. In this review, we discuss the state of the art of the Fontan strategy by assessing survival and risk factors for mortality. Complications of the Fontan circulation, such as cardiac arrhythmia, thromboembolism, and protein-losing enteropathy, are discussed. Common surgical and catheter-based interventions following Fontan completion are outlined. We describe functional status measurements such as quality of life and developmental outcomes in the contemporary Fontan patient. The current role of drug therapy in the Fontan patient is explored. Furthermore, we assess the current use and outcomes of mechanical circulatory support in the Fontan circulation and novel surgical innovations. Despite large improvements in outcomes for contemporary Fontan patients, a large burden of disease exists in this patient population. Continued efforts to improve outcomes are warranted. Several remaining challenges in the Fontan field are outlined.

Modified Technique to Create Diabolo Stent Configuration

Diabolo stent configuration aids in stent positioning, stability, and creating a controlled defect with a predetermined size. A number of techniques to create the diabolo configuration have been previously described. The indications for creating a controlled "defect" are rapidly growing and include the Fontan circulation, patients with severe end-stage pulmonary hypertension, restrictive atrial communication in the setting of hypoplastic right or left heart syndrome, and diastolic left heart failure. We describe an alternative technique using a prefabricated readily available tool (gooseneck snare) to create a diabolo stent configuration. The chosen balloon expandable stent is mounted on a 5-mm gooseneck snare centered on an angioplasty catheter larger than 5 mm diameter. When deployed, the snare restricts the central waist to 5 mm and both ends expand to a larger diameter creating a dumbbell/diabolo configuration. A total of six diablo stent configurations were successfully implanted in four patients with failing Fontan physiology; five to create a transcatheter fenestration and one to relieve atrial septal restriction. Data expressed as median and IQR. Their weight was 24.8 kg (19.6-46.95), and age years was 9.2 (6.28-13.23). There were no complications and a consistent diabolo configuration with a 5-mm central waist was created in all patients. The snare serves as a sterile, preconfigured, radiopaque, readily available tool of adequate length and strength, to create consistent diabolo stent configuration without any modifications. This technique is a simple, reproducible, and easy to learn.

Native atrial septal restriction after Fontan palliation successfully treated with transcatheter Diabolo stent

A 6-year-old male child born with hypoplastic left heart syndrome (HLHS) was palliated with an extracardiac nonfenestrated Fontan procedure (18-mm Gore-Tex tube graft). He developed low-pressure (mean Fontan pressure 10 mmHg) protein-losing enteropathy 6 months after Fontan palliation. After initially responding to medical therapy and transcatheter pulmonary artery stent implantation, he developed medically refractory protein-losing enteropathy. At this time, his transthoracic echocardiogram showed new restriction across his native atrial septum with an 8 mmHg mean gradient. Cardiac catheterization now showed high-pressure (mean Fontan pressure 18-20 mmHg) protein-losing enteropathy and a new 6 mmHg mean gradient across the atrial septum. To avoid cardiopulmonary bypass, he underwent successful transcatheter relief of atrial septal restriction and creation of a fenestration with rapid clinical and biochemical improvement of his protein-losing enteropathy.