Percutaneous use of stents to correct pulmonary artery stenosis in young children after cavopulmonary anastomosis

Ascending aortic extension to increase aortopulmonary space after comprehensive stage II palliation

Aortic reconstruction at the time of the comprehensive stage II (CSII) procedure can be complicated by compression within the aortopulmonary space resulting in airway or pulmonary artery narrowing. We describe our experience with 2 patients with hypoplastic left heart syndrome and pulmonary artery stenosis after the CSII procedure. Both patients underwent an aortic extension with a Hemashield interposition graft to open up the aortopulmonary space. The patients were discharged from the hospital. In all cases the aortopulmonary space was enlarged, and the pulmonary arteries and airway were free from compression. Aortic extension is an option to be considered in children with pulmonary artery compression who previously had a CSII procedure.

Aortopulmonary collateral flow quantification by MR at rest and during continuous submaximal exercise in patients with total cavopulmonary connection

BACKGROUND

Aortopulmonary collateral flow is considered to have significant impact on the outcome of patients with single ventricle circulation and total cavopulmonary connection (TCPC). There is little information on collateral flow during exercise.

PURPOSE

To quantify aortopulmonary collateral flow at rest and during continuous submaximal exercise in clinical patients doing well with TCPC.

STUDY TYPE

Prospective, case controlled.

POPULATION

Thirteen patients with TCPC (17 (11-37) years) and 13 age and sex-matched healthy controls (18 (11-38) years).

FIELD STRENGTH

1.5T; free breathing; phase sensitive gradient echo sequence.

ASSESSMENT

Blood flow in the ascending and descending aorta and superior vena cava were measured at rest and during continuous submaximal physical exercise in patients and controls. Systemic blood flow (Q_s ) was assumed to be represented by the sum of flow in the superior caval vein (Q_svc ) and the descending aorta (Q_AoD ) at the diaphragm level. Aortopulmonary collateral flow (Q_coll ) was calculated by subtracting Q_s from flow in the ascending aorta (Q_AoA ).

STATISTICS

Mann-Whitney U-test and Wilcoxon test for comparison between groups and between rest and exercise.

RESULTS

Absolute collateral flow in TCPC patients at rest was 0.4 l/min/m² (-0.1-1.2), corresponding to 14% (-2-42) of Q_s . Collateral flow did not change during exercise (difference -0.01 (-0.7-1.0) l/min/m² , P = 0.97). TCPC patients had significantly lower Q_s at rest (2.5 (1.6-4.1) vs. 3.5 (2.6-4.8) l/min/m² , P = 0.001) and during submaximal exercise (3.2 (2.0-6.0) vs. 4.8 (3.3-6.9) l/min/m² , P = 0.001), compared to healthy controls. The increase in Q_s with exercise was also significantly lower in patients than in healthy controls (median 0.6 vs. 1.2 l/min/m² , P < 0.02).

DATA CONCLUSION

Clinical patients doing well with TCPC have significant aortopulmonary collateral flow at rest (14% of Q_s ) compared to healthy controls, which does not change during submaximal exercise.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1509-1516.

Intra-procedural Bronchoscopy to Prevent Bronchial Compression During Pulmonary Artery Stent Angioplasty

Stenosis of the pulmonary arteries frequently occurs during staged palliation of hypoplastic left heart syndrome and variants, often necessitating stent angioplasty. A complication of stent angioplasty is compression of the ipsilateral mainstem bronchus. Following such a case, we re-evaluated our approach to PA stent angioplasty in these patients. The incident case is described. A retrospective observational study of children and adults with superior (SCPC) and/or total cavopulmonary connection (TCPC) undergoing left pulmonary artery (LPA) stent angioplasty between January 1, 2005 and January 5, 2014 and subsequent chest CT was performed to assess the incidence of bronchial compression. The current strategy of employing bronchoscopy to assess bronchial compression during angioplasty is described with short-term results. Sixty-five children and adults underwent LPA stent angioplasty. Other than the incident case, none had symptomatic bronchial compression. Of the total study population, 12 % had subsequent CT, of which one subject had moderate bronchial compression. To date, seven subjects have undergone angioplasty of LPA stenosis and bronchoscopy. In one case, stent angioplasty was not performed because of baseline bronchial compression, exacerbated during angioplasty. In the rest of cases, mild-moderate compression was seen during angioplasty. Following stent angioplasty, the resultant compression was not worse than that seen on test angioplasty. Bronchial compression is a rare complication of stent angioplasty of the pulmonary arteries in children and adults with SCPC/TCPC. Angioplasty of the region of interest with procedural bronchoscopy can help to identify patients at risk of this complication.

Hemodynamic effects of left pulmonary artery stenosis after superior cavopulmonary connection: a patient-specific multiscale modeling study

OBJECTIVE

Currently, no quantitative guidelines have been established for treatment of left pulmonary artery (LPA) stenosis. This study aims to quantify the effects of LPA stenosis on postoperative hemodynamics for single-ventricle patients undergoing stage II superior cavopulmonary connection (SCPC) surgery, using a multiscale computational approach.

METHODS

Image data from 6 patients were segmented to produce 3-dimensional models of the pulmonary arteries before stage II surgery. Pressure and flow measurements were used to tune a 0-dimensional model of the entire circulation. Postoperative geometries were generated through stage II virtual surgery; varying degrees of LPA stenosis were applied using mesh morphing and hemodynamics assessed through coupled 0-3-dimensional simulations. To relate metrics of stenosis to clinical classifications, pediatric cardiologists and surgeons ranked the degrees of stenosis in the models. The effects of LPA stenosis were assessed based on left-to-right pulmonary artery flow split ratios, mean pressure drop across the stenosis, cardiac pressure-volume loops, and other clinically relevant parameters.

RESULTS

Stenosis of >65% of the vessel diameter was required to produce a right pulmonary artery:LPA flow split <30%, and/or a mean pressure drop of >3.0 mm Hg, defined as clinically significant changes.

CONCLUSIONS

The effects of <65% stenosis on SCPC hemodynamics and physiology were minor and may not justify the increased complexity of adding LPA arterioplasty to the SCPC operation. However, in the longer term, pulmonary augmentation may affect outcomes of the Fontan completion surgery, as pulmonary artery distortion is a risk factor that may influence stage III physiology.

Role of stents in congenital heart disease

For more than 10 years, balloon-expandable intravascular stents have become an integral part of treatment for obstructive vascular lesions in children and adults with congenital heart disease. The initial problems with stents, such as sharp edges, rigid frame and unacceptable shortening when over-expanded have been overcome to a large extent with the newer designs. The problems related to delivery of stents, such as stent migration, balloon rupture, flaring of the edges of the stent, rupture of vessels and milking of the stent off the balloon, have also been overcome by newer designs of balloons. The failure of growth of balloon-expandable stents with the growth of the child is managed by redilation with or without additional stenting and newer growth stents. Self-expanding stents are not appropriate for use in growing children due to the limitation of their maximum diameters. The development of biodegradable stents may overcome these disadvantages in the future. Various new developments have recently occurred. Covered stents are ideal for treating acute vessel rupture and in isolating vascular aneurysms. Drug-eluting stents may prevent restenosis, but have not been used in children. Valved stents are a recent innovation for the treatment of regurgitant pulmonary valves.

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.

Ascending Aortic Extension for Enlargement of the Aortopulmonary Space in Children with Pulmonary Artery Stenosis

BACKGROUND

Complex reconstruction of the aorta can be complicated by compression within the aortopulmonary space resulting in airway or pulmonary artery narrowing. Pulmonary artery compression is especially problematic in children with single ventricle physiology in which an increase in pulmonary vascular resistance may impair systemic venous flow and reduce cardiac output.

METHODS

We operated on 7 patients (mean age, 2.9 years) with pulmonary artery stenosis presenting after a complex neonatal aortic reconstruction. All 7 patients underwent aortic extension with a polytetrafluoroethylene interposition graft and homograft patch angioplasty of the pulmonary artery to open the aortopulmonary space and relieve pulmonary artery narrowing. Five patients (hypoplastic left heart syndrome, n = 2; transposition of the great arteries with tricuspid atresia and aortic hypoplasia, n = 1; double outlet right ventricle with aortic hypoplasia, n = 2) had previously undergone first stage repairs for single ventricle morphology. Two of the patients had multiple interim procedures, including placement of bilateral pulmonary artery stents, prior to our repair.

RESULTS

There was 1 early death secondary to fungal sepsis. Six patients were discharged from the hospital. There was 1 late, noncardiac death from aspiration pneumonia in a patient with a severe craniofacial defect. Follow-up echocardiograms in the intermediate term have demonstrated relief of pulmonary artery narrowing and unobstructed aortic flow.

CONCLUSIONS

Aortic extension is an option in children with pulmonary artery compression of structures in the aortopulmonary space after complex aortic reconstruction.

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.

Late distortion of the original Palmaz stent implanted in postoperative lesions associated with congenital heart disease

The objective of this study was to report late distortion of a Palmaz stent. Late distortion of an original Palmaz stent, implanted in an extracardiac lesion, is rare. We completed a 1-year follow-up of 54 patients who had been implanted with 80 Palmaz stents in extracardiac lesions. Distortion of two stents was detected in two patients. For case 1, we implanted a P188 stent for supravalvar pulmonary stenosis complicating an arterial switch operation in a 14-year-old girl. Seven months later, we found compression of the stent. Although we implanted two P308 stents anterior to the distorted stent, distortion of both stents developed after 1 month. Two more P308 stents placed inside each stent were gradually recompressed. A CAT scan showed compression of the stent by a dilated sinus of valsalva. For case 2, we implanted a P308 stent for stenosis of the superior vena cava after Williams operation in an 11-year-old boy. A chest X-ray documented longitudinal compression of the stent 27 months after implantation and a CAT scan showed the ascending aorta was in contact with the stent. A Palmaz stent may be distorted when implanted in a lesion adjacent to a pulsating aorta.

Feasibility and safety of immediate perioperative implantation of intravascular stents in cavopulmonary pathways

Fontan-type procedures are widely used for palliation of patients with many forms of a functional univentricular heart. An ideal Fontan circuit should be free of any distortion or stenosis. The use of stents for the treatment of stenotic and hypoplastic vessels is well established in pediatric cardiac practice. We report the successful use of endovascular stents during the immediate postoperative period in patients undergoing cavopulmonary anastomoses.

Interventional strategies in the management of peripheral pulmonary artery stenosis

Peripheral pulmonary artery stenosis challenges therapeutic algorithms for the management of congenital heart malformations. Surgical repair of the proximal pulmonary artery lesion remains with a high recurrence rate while the distal lesions are difficult to access. With the development of transcatheter interventional strategies in the early 1980s, a number of transcatheter treatment options became available. In this review, we summarize the current state of the art for interventional strategies in the management of peripheral pulmonary artery stenosis.

Descending thoracic aorta to left pulmonary artery fistula after stent implantation for acquired left pulmonary artery stenosis

This is a case report of a Fontan patient with previous Potts anastomosis who underwent stent implantation for left pulmonary artery stenosis. At follow-up the patient developed a fistula between the descending thoracic aorta and the left pulmonary artery at the site of the stent. This represents a late complication of stent placement.

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

The purpose of this study was to clarify desired stent sizes for stenotic lesions in the post-Fontan circulation. Using angiograms from 22 patients before and at late follow-up (> or = 15 years) after the Fontan operation, we measured the maximum diameters of the proximal pulmonary arteries (PA) and the descending aorta. The diameters of the PA ipsilateral to the inferior vena cava, contralateral to the inferior vena cava, and descending aorta after the Fontan were 10.6-22.6 (15.8 +/- 3.3), 8.0-19.1 (12.9 +/- 3.1), and 12.1-18.9 (15.8 +/- 2.0) mm, respectively, while the percent of normal predicted diameters (% N) were 55%-104% (70% +/- 14%), 38%-99% (66% +/- 17%), and 46%-74% (60% +/- 7%), respectively. Despite somatic growth, the % N of all vessel diameters decreased significantly after the Fontan operation. In conclusion, smaller-sized stents should be acceptable for both the pulmonary artery and descending aorta in the Fontan circulation.

Comparison of results of stent implantation in small (<20 kg) children versus larger children with pulmonary artery stenoses

We compared the results of stent implantation for pulmonary artery stenoses in patients weighing <20 kg (group 1, 17 patients, 21 stents) versus those weighing > or = 20 kg (group 2, 11 patients, 13 stents). There was no significant difference in the mean percent increase in diameter or mean percent gradient reduction acutely and at short-term follow-up between group 1 and 2 patients.

Spontaneous acquisition of discontinuous pulmonary arteries

BACKGROUND

Discontinuous pulmonary arteries have been considered a rare complication of systemic-to-pulmonary shunt operations. We report a series of children who spontaneously acquired pulmonary artery discontinuity.

METHODS

All children from 1989 through 1995 with congenital pulmonary atresia were reviewed.

RESULTS

Pulmonary artery discontinuity developed in 29% (15 patients), none related to shunt operation. In 6 of 15 patients, the neonatal angiogram showed a pattern that seemed to predict subsequent discontinuity; in 9 of 15, pulmonary arteriography was normal at birth. Two clinical patterns were identified: an early rapid acquisition of discontinuity within hours to days, and a delayed, more subtle development that occurred over months. Eight of 15 have died. Pathologic studies in 6 children showed ductal tissue extending along and into the pulmonary artery wall as well as intimal hypertrophic reaction and maladaptive remodeling.

CONCLUSIONS

Children with congenital pulmonary atresia may experience spontaneous acquisition of pulmonary artery discontinuity. Ductal tissue is responsible for local pulmonary artery distortion and discontinuity; this may be exacerbated by previous prostaglandin E1 administration. Clinical algorithms are suggested for patients with pulmonary atresia.