Arterial stents in the management of neurofibromatosis and renovascular hypertension in a pediatric patient: case report of a new treatment modality

Renal artery stenting in a 2-year-old child with resistant hypertension and neurofibromatosis

The occurrence of vascular lesions in neurofibromatosis is uncommon but well documented. These vascular lesions when present, occur predominantly in the kidneys, endocrine glands, heart and gastrointestinal tract, causing stenosis or obliteration of the lumen. We report a case of uncontrolled resistant hypertension in a 2-year-old child presenting with neurofibromatosis who was found to have a high-grade ostial left renal artery stenosis and obliteration of the right renal artery. As the right kidney was small and hypo-functioning, and its renal artery was totally occluded, we subjected the child to a left renal angioplasty and bailout stenting. Following stenting, the blood pressure decreased with anti-hypertensive treatment. Based on a review of the literature, and to the best of our knowledge, this is the youngest child to have undergone renal artery stenting.

Disease Beyond the Arch: A Systematic Review of Middle Aortic Syndrome in Childhood

BACKGROUND

Middle aortic syndrome (MAS) is a rare clinical entity in childhood, characterized by a severe narrowing of the distal thoracic and/or abdominal aorta, and associated with significant morbidity and mortality. MAS remains a relatively poorly defined disease. This paper systematically reviews the current knowledge on MAS with respect to etiology, clinical impact, and therapeutic options.

METHODS

A systematic search of 3 databases (Embase, MEDLINE, and Cochrane Central Register of Controlled Trials) yielded 1,252 abstracts that were screened based on eligibility criteria resulting in 184 full-text articles with 630 reported cases of childhood MAS. Data extracted included patient characteristics, clinical presentation, vascular phenotype, management, and outcomes.

RESULTS

Most cases of MAS are idiopathic (64%), 15% are associated with Mendelian disorders, and 17% are related to inflammatory diseases. Extra-aortic involvement including renal (70%), superior mesenteric (30%), and celiac (22%) arteries is common, especially among those with associated Mendelian disorders. Inferior mesenteric artery involvement is almost never reported. The majority of cases (72%) undergo endovascular or surgical management with residual hypertension reported in 34% of cases, requiring medication or reintervention. Clinical manifestations and extent of extra-aortic involvement are lacking.

CONCLUSIONS

MAS presents with significant involvement of visceral arteries with over two thirds of cases having renal artery stenosis, and one third with superior mesenteric artery stenosis. The extent of disease is worse among those with genetic and inflammatory conditions. Further studies are needed to better understand etiology, long-term effectiveness of treatment, and to determine the optimal management of this potentially devastating condition.

Transcatheter double stent implantation for treatment of middle aortic coarctation syndrome

A 13-year-old boy presented with severe systemic hypertension. His upper limb blood pressure measured 190/100 mm Hg and lower limb blood pressure measured 98/64 mm Hg. The brachial pulses were bounding and femoral pulses were not palpable. Echocardiography and magnetic resonance angiography confirmed middle aortic syndrome. There was severe diffuse thoraco-abdominal coarctation with continuous Doppler run-off. Cardiac catheterization was undertaken and using a retrograde approach two Advanta V12 stents were implanted in the complex thoraco-abdominal coarctation. The gradient across the coarctation was reduced from 80 to 40 mm Hg gradient with a significant improvement in the luminal diameter of the aorta. His upper limb blood pressure reduced to 142/78 mm Hg six weeks later.

[State of the art: interventional radiology management of renovascular hypertension]

The management of renal artery stenosis (RAS) has been the subject of numerous clinical studies and recommendations, most frequently with regards to atherosclerotic RAS. We present the current recommendations from the French Society of Cardiac and Vascular Imaging updated from a recent literature review (April 2008) with regards to medical, endovascular and surgical management of atheroscletotic and non-atherosclerotic RAS. The evidence-based recommendations are ranked by level.

Renovascular hypertension in children

Renovascular disease is an uncommon but important cause of hypertension in children. It is usually diagnosed after a long delay because blood pressure is infrequently measured in children and high values are generally dismissed as inaccurate. Many children with renovascular disease have abnormalities of other blood vessels (aorta, cerebral, intestinal, or iliac). Individuals suspected of having the disorder can be investigated further with CT, MRI, or renal scintigraphy done before and after administration of an angiotensin-converting-enzyme inhibitor, but angiography is still the gold standard. Most children with renovascular disease will need interventional or surgical treatment. Endovascular treatment with or without stenting will cure or reduce high blood pressure in more than half of all affected children. Surgical intervention, if needed, should be delayed preferably until an age when the child is fully grown. Modern treatment provided by a multidisciplinary team of paediatric nephrologists, interventional radiologists, and vascular surgeons offers good long-term treatment results.

Vascular abnormalities in patients with neurofibromatosis syndrome type I: clinical spectrum, management, and results

PURPOSE

Neurofibromatosis type I (NF-I) is an autosomal dominant disorder affecting one in 3000 individuals. Vascular abnormalities are a well-recognized manifestation of NF-I. The purpose of this study is to review the spectrum, management, and clinical outcome of patients with vascular abnormalities and NF-I.

METHODS

We retrospectively reviewed 31 patients (15 males, 16 females) with clinical NF-I and vascular abnormalities identified from imaging or operative findings between 1976 and 2005.

RESULTS

The diagnosis of NF-I was made at a mean age of 11 +/- 10 years with vascular lesions identified at a mean age of 38 +/- 16 years. There were 76 vascular abnormalities, including 38 aneurysms, 20 arterial stenoses, 5 arteriovenous malformations (AVM), 5 arteries compressed or invaded by neural tumors, and 6 abnormalities of the heart valves. Arterial lesions were located in the aorta (n = 17) and in the renal (n = 12), mesenteric (n = 12), carotid-vertebral (n = 10), intracerebral (n = 4), and subclavian-axillary and iliofemoral arteries (3 each). Interventions were required in 23 patients (74%); 15 underwent 24 arterial reconstructions, including 9 renal, 8 aortic, 4 mesenteric, 2 carotid, and 1 femoral. The other eight patients had excision of AVM in three, vessel ligation in two, and clipping of cerebral aneurysms, coil embolization of hepatic aneurysms, and left thoracotomy in one patient each. One patient died of ruptured abdominal aortic aneurysm. Six patients (26%) had postoperative complications, including pneumonia in two, and stroke, acalculous cholecystitis, brachial plexopathy and chylothorax in one patient each. The median follow up was 4.1 years (range, 6 months to 20 years). Late vascular problems developed in three patients, including graft stenoses in two and rupture of another aortic aneurysm in one. Freedom from graft-related complications was 83% at 10 years. Patient survival at 10 years was 77%, less than the 86% expected survival for the general population (P < .001).

CONCLUSION

Patients with NF-I have a wide spectrum of vascular abnormalities, most notably aneurysms or stenoses of the aortic, renal, and mesenteric circulation. Operative treatment of symptomatic patients with vascular lesions or large aneurysms is safe, effective, and durable.

Cutting Balloon Angioplasty in Children with Resistant Renal Artery Stenosis

Children with systemic hypertension resulting from a renovascular stenosis commonly have fibromuscular dysplasia and respond to percutaneous transluminal renal angioplasty (PTRA). There is a subset of children, however, with conditions that appear to be resistant to PTRA (eg, syndromic renal artery stenosis and arteritis). These patients are often treated surgically. The development of the cutting balloon may provide a minimally invasive alternative to surgery in these individuals. Associated adverse events may include recurrent stenosis, arterial occlusion with renal loss, and arterial rupture with extravasation and pseudoaneurysm formation. Some of these adverse events can be successfully treated with percutaneous interventional techniques. The authors present four cases of cutting balloon angioplasty performed at two large metropolitan children's hospitals in children with resistant renal artery stenosis.

Use of Palmaz stents in a newborn with congenital aneurysms and coarctation of the abdominal aorta

Anomalies of the abdominal aorta are rare in the pediatric population limiting the reported knowledge base from which management decisions can be made. A 3-week-old male with congenital abdominal aortic coarctation and multiple aneurysms presented with malignant hypertension. We report the safe deployment of overlapping Palmaz stents using a 4-French catheter delivery system with significant relief of the coarctation gradient and restoration of adequate renal perfusion.

Renal artery stenosis and aneurysms associated with neurofibromatosis

Renal artery lesions associated with neurofibromatosis may involve stenosis and aneurysm formation at all levels of the renal artery to the intraparenchymal branches, and usually are associated with hypertension. A 13-year-old boy with type I neurofibromatosis and severe hypertension presented with multiple aneurysms and multiple stenotic lesions in the renal artery and segmental arteries. The patient underwent ex-vivo renal artery repair with autologous hypogastric artery and autotransplantation to the iliac fossa and was clinically improved. The characteristic histologic findings are presented. A review of the recent literature comparing different treatment modalities for renovascular hypertension in children with neurofibromatosis suggests that surgery remains the best treatment alternative.

Reconstruction of stenotic or occluded iliofemoral veins and inferior vena cava using intravascular stents: re-establishing access for future cardiac catheterization and cardiac surgery

OBJECTIVES

The study evaluated the safety and efficacy of stent reconstruction of stenotic/occluded iliofemoral veins (IFV) and inferior vena cava (IVC).

BACKGROUND

Patients with congenital heart defects and stenotic or occluded IFV/IVC may encounter femoral venous access problems during future cardiac surgeries or catheterizations.

METHODS

Twenty-four patients (median age 4.9 years) underwent implantation of 85 stents in 22 IFV and 6 IVC. Fifteen vessels were severely stenotic and 13 were completely occluded. Although guide wires were easily passed across the stenotic vessels, occluded vessels required puncture through the thrombosed sites using a stiff wire or transseptal needle. Once traversed, the occluded site was dilated serially prior to stent implantation.

RESULTS

Following stent placement, the mean vessel diameter increased from 0.9 +/- 1.6 to 7.4 +/- 2.6 mm (p < 0.05). Twenty-one of 28 vessels had long segment stenosis/occlusion requiring two to seven overlapping stents. Repeat catheterizations were performed in seven patients (9 stented vessels) at mean follow-up of 1.6 years. Seven vessels remained patent with mean diameter of 6.4 +/- 2.0 mm. Two vessels were occluded, but they were easily recanalized and redilated. Echocardiographic follow-up in two patients with IVC stents demonstrated wide patency. In four additional patients, a stented vessel was utilized for vascular access during subsequent cardiac surgery (n = 3) and endomyocardial biopsy (n = 1). Therefore, 13 of 15 stented vessels (87%) remained patent at follow-up thus far.

CONCLUSIONS

Stenotic/obstructed IFV and IVC may be reconstructed using stents to re-establish venous access to the heart for future cardiac catheterization and/or surgeries.

Treatment of abdominal aortic pseudoaneurysm with covered stents in a pediatric patient

An occasional complication of redilating stents placed in children is false aneurysm. We report the use of covered stents to treat a false aneurysm of the abdominal aorta in an adolescent girl with neurofibromatosis and abdominal coarctation of the aorta.

Stent treatment for coarctation of the aorta: intermediate term follow up and technical considerations

OBJECTIVE

To report the initial and intermediate term results of stent implantation in children with coarctation of the aorta.

PATIENTS AND DESIGN

17 patients with coarctation of the aorta underwent stent implantation (median age 11 years, range 0.4-15 years); six were treated for isolated coarctation, nine for recurrent coarctation (five after surgical repair and four after balloon dilatation), and two for complex long segment coarctation.

INTERVENTIONS

The procedure was guided by a second catheter placed transseptally in the left ventricle or the aorta proximal to the coarctation site, for angiographic and haemodynamic monitoring during the procedure. Twenty two stents were implanted in 17 patients. One of the patients with long segment coarctation received four stents and the other three. Palmaz 4014 stents were placed in 11 patients, Palmaz 308 in five, and Palmaz 154 in one.

RESULTS

Immediately after stent implantation the peak systolic gradient (mean (SD)) fell from 50.0 (24.5) to 2.1 (2.4) mm Hg (p < 0.05). The diameter of the stenotic lesion increased from 5.1 (1.5) mm to 13.9 (2.4) mm (p < 0.05). There were no deaths or procedure related complications. At a median follow up of 33 months, no cases of recoarctation were identified, either clinically (0/17; 0%, 95% confidence interval (CI) 0% to 19%) or angiographically (0/13; 0%, 95% CI 0% to 25%).

CONCLUSIONS

Stent implantation for the treatment of coarctation of the aorta appears to have very low morbidity and mortality, and reasonable intermediate term results. Long term freedom from recoarctation using this method remains to be determined in comparison with simple balloon dilatation.

Stent dilation of superior vena cava and innominate vein obstructions permits transvenous pacing lead implantation

The purpose of this study was to assess the feasibility of stent dilation of venous obstructions/occlusions to permit transvenous pacing lead implantation. Innominate vein or superior vena cava (SVG) obstruction may preclude the implantation of transvenous pacing leads. Patients with d-transposition of the great arteries, after a Mustard or Senning procedure, and children with previously placed transvenous pacing leads are at higher risk for this vascular complication. From May 1993 to January 1996, eight pediatric patients who underwent transvenous pacing lead implantation or replacement were found to have significant innominate vein or SVC obstruction or occlusion. Utilizing intravascular stents, a combined interventional and electrophysiological approach was used to relieve the venous obstruction and to permit implantation of a new transvenous pacing lead. Two patients had complete SVC occlusion requiring puncture through the obstruction with a transseptal needle. Vessel recanalization was achieved with balloon dilation and stent implantation. The remaining six patients had severe venous obstruction with a mean minimum diameter of 3.1 +/- 3.3 mm. The mean pressure gradient across the obstructed veins was 8.6 +/- 7.3 mmHg. Following implantation of 15 Palmaz P308 stents in eight vessels, the mean diameter increased to 14.2 +/- 1.9 mm and the mean pressure gradient across the stented vessels decreased to 1.0 +/- 2.0 mmHg. A transvenous pacing lead was implanted successfully through the stent(s) immediately or 6-8 weeks later. Innominate vein and SVC obstruction can be safely and effectively relieved with intravascular stents and permit immediate or subsequent transvenous pacing lead implantation.

Use of balloon-expandable stents for coarctation of the aorta: initial results and intermediate-term follow-up

OBJECTIVES

In this study we report our preliminary results and intermediate-term follow-up (up to 3.5 years) of stent implantation for coarctation of the aorta (COA).

BACKGROUND

Balloon angioplasty has gained acceptance as a modality of treatment for COA. Some patients do not respond optimally to balloon angioplasty alone. Balloon-expandable stents have been used in pulmonary arteries and large systemic arteries such as the femoroiliac vessels, with a significant improvement in vessel patency and a reduction in the pressure gradient compared with balloon angioplasty alone.

METHODS

Nine patients (>10 years old) with COA in whom balloon dilation alone was thought to be ineffective underwent stent implantation. Seven patients had a previous operation or balloon dilation, or both, to relieve their coarctation but had a significant residual/recurrent gradient.

RESULTS

At the time of stent implantation, the systolic and mean gradients decreased from a mean (+/-SEM) of 37 +/- 7 and 14 +/- 3 mm Hg to 4 +/- 1 and 2 +/- 0.6 mm Hg, respectively (p < or = 0.002). The coarctation diameter increased from a mean of 9 +/- 1 to 15 +/- 1 mm (p < 0.002). The patients have been followed for up to 42 months (mean 18, median 13) with no complications; the stents remain in position with no fracture. One patient underwent further successful dilation 3 years after stent implantation because of an exercise-induced gradient. No other intervention has been required. The systolic gradient at latest follow-up is 7 +/- 2 mm Hg. Only two (a 44-year old with diabetes and a 50-year old with long-standing hypertension) of five patients previously requiring antihypertensive treatment still remain on medications for blood pressure control.

CONCLUSIONS

The use of stents in COA is a feasible alternative to surgical repair or balloon angioplasty in selected patients with an effective gradient reduction. Intermediate-term follow-up shows excellent gradient relief, with no complications in this group of patients.

Noncoronary vascular stenting

The aim of this report is to review the current state of the art with respect to noncoronary vascular stenting. A review of the literature was performed, examining the historical aspects of stent design and usage, as well as the currently available designs and their respective functions. When appropriate, we note our personal experience with stent placement in each anatomic site. Currently available stents take many forms: balloon-expandable, self-expanding, and shape-memory alloy. Varied design modifications have been made to maximize the open area, to limit the surface area of the prosthesis, to increase (or decrease) flexibility, and to increase (or decrease) stent plasticity and elasticity. Modifications to minimize thrombogenicity are also underway. The clinical uses of the currently available stents in multiple anatomic locations will be discussed. Intravascular stents are an addition to the arsenal available for prolonging blood vessel patency.