Potential goals for the dimensions of the pulmonary arteries and aorta with stenting after the Fontan operation

Fontan pathway growth: a quantitative evaluation of lateral tunnel and extracardiac cavopulmonary connections using serial cardiac magnetic resonance

BACKGROUND

Typically, a Fontan connection is constructed as either a lateral tunnel (LT) pathway or an extracardiac (EC) conduit. The LT is formed partially by atrial wall and is assumed to have growth potential, but the extent and nature of LT pathway growth have not been well characterized. A quantitative analysis was performed to evaluate this issue.

METHODS

Retrospective serial cardiac magnetic resonance data were obtained for 16 LT and 9 EC patients at 2 time points (mean time between studies, 4.2 ± 1.6 years). Patient-specific anatomies and flows were reconstructed. Geometric parameters of Fontan pathway vessels and the descending aorta were quantified, normalized to body surface area (BSA), and compared between time points and Fontan pathway types.

RESULTS

Absolute LT pathway mean diameters increased over time for all but 2 patients; EC pathway size did not change (2.4 ± 2.2 mm vs 0.02 ± 2.1 mm, p < 0.05). Normalized LT and EC diameters decreased, while the size of the descending aorta increased proportionally to BSA. Growth of other cavopulmonary vessels varied. The patterns and extent of LT pathway growth were heterogeneous. Absolute flows for all vessels analyzed, except for the superior vena cava, proportionally to BSA.

CONCLUSIONS

Fontan pathway vessel diameter changes over time were not proportional to somatic growth but increases in pathway flows were; LT pathway diameter changes were highly variable. These factors may impact Fontan pathway resistance and hemodynamic efficiency. These findings provide further understanding of the different characteristics of LT and EC Fontan connections and set the stage for further investigation.

Large-diameter graft-stent (Advanta V12) implantation in various locations: early results

OBJECTIVES

Transcatheter stent placement carries the risk of cardiovascular aneurysm or rupture. Covered stent implantation reduces these risks. The recently marketed Advanta V12 large-diameter-covered stent is pre-mounted and requires 9 (8)-11 Fr delivery systems. The aim was to report on the early results of the treatment of various cardiovascular obstructions by the implantation of a new polytetrafluoroethylene-covered stent (V12).

METHODS

Graft stents on balloons with a diameter (12, 14, 16 millimetres) sufficient to anchor the stent in various obstructions (congenital aortic coarctation, n = 5; obstruction after ascending aorta repair, n = 2; pulmonary arteries, n = 5; inferior caval vein, n = 1; atretic superior caval vein, n = 1; pulmonary vein obstruction, n = 1; and right ventricular outflow tract, n = 1) were implanted using the smallest available delivery system. Secondary dilation with larger-diameter balloons was performed when the residual pressure was gradient, the stent-vessel wall relationship or stent re-coiling due to different reasons needed a re-intervention by pure ballooning or second stent placement.

RESULTS

All 16 patients aged 5-46 years underwent V12 implantation. The variability of the treated lesions and the need for additional interventions were responsible for large ranges in fluoroscopy time between 7.3 to 48.2 minutes (median 17.3). Considering the additional procedures, the V12 stent achieved the desired result in all cases. There were no major complications. At short-term median follow-up of 2 months, all patients are alive and well with no evidence of stent failing.

CONCLUSION

These initial results show that the covered Advanta V12 large-diameter stent is safe and effective in the immediate treatment of various cardiovascular obstructions. Long-term follow-up is required.

Pulmonary artery stent implantation in children with single ventricle malformation before and after completion of partial and total cavopulmonary connections

OBJECTIVES

Relief of pulmonary artery stenosis before and after cavopulmonary connections (CPC) in patients with single ventricle malformation is essential to optimize pulmonary hemodynamics. We evaluated the risk factors for pulmonary artery stenosis and assessed the outcome after stent implantation.

INTERVENTIONS

Seventeen stents in twelve patients were implanted for pulmonary artery stenosis before and after CPC at a mean age of 4.5 (0.1-17.6) years.

RESULTS

Fourteen stents were placed in the left pulmonary artery (82%) and three stents in the right pulmonary artery (18%). One stent was implanted intraoperatively. Mean time between surgery and stent implantation was 28 (1-132) months. The mean (SD) size of the pulmonary artery stenosis was 3.1 +/- 2.1 mm before and 8.1 +/- 3.3 mm (P < 0.001) after stent implantation. Six out of seventeen stents (35.2%) had to be redilated after a mean time interval of 19 (5-48) months. Two patients' stents were removed during the next surgical procedure; both needed an early restenting of the affected vessel. There were no procedure-related complications for stent implantation or redilatation. Anatomical risk factors for pulmonary artery stenosis were right aortic arch and hypoplastic pulmonary arteries, whereas dilatation of the ascending aorta for LPA stenosis and Blalock-Taussig shunt for RPA stenosis were surgical risk factors.

CONCLUSIONS

Stent implantation to treat pulmonary artery stenosis in pediatric patients with CPC is effective and can be realized safely. Close follow-up is recommended in patients with risk for pulmonary artery stenosis. During total cavopulmonary connection, previously implanted stents at that site should be left in place or be changed in a hybrid procedure to a larger diameter, because the etiology of stenosis may persist after surgery and the surgical removal could result in vessel injury that promotes restenosis.

The CP stent--short, long, covered--for the treatment of aortic coarctation, stenosis of pulmonary arteries and caval veins, and Fontan anastomosis in children and adults: an evaluation of 60 stents in 53 patients

OBJECTIVE

To evaluate the feasibility and usefulness of the Cheatham platinum (CP) stent in a broad spectrum of lesions.

METHODS

Retrospective analysis of 60 implanted CP stents (11-80 mm lengths, 12 covered) between September 2001 and March 2004.

PATIENTS

53 patients aged 2.5-68 years (median 17 years). Body weight ranged from 12-95 kg (median 52 kg). Thirty six patients had aortic (re)coarctation; seven of them had functionally interrupted aortic arches. Thirteen patients had pulmonary artery stenosis and four had stenosis of caval veins or conduits in a total cavopulmonary connection (TCPC).

RESULTS

Arterial pressure gradients dropped from 33 mm Hg (range 20-80 mm Hg) to 5 mm Hg (range 0-10 mm Hg) and pressure gradients in TCPC or caval veins dropped from 4 mm Hg (range 4-20 mm Hg) to 0 mm Hg (range 0-3 mm Hg). All stents were placed in the target lesion without complications. Three stent fractures without clinical instability were noted.

CONCLUSIONS

The CP stent is suitable for the treatment of vessel stenosis in congenital heart diseases from childhood to adulthood. Whether these good results will be stable in the long term needs to be investigated.