Restriction of congenital portosystemic shunt using the modified microvascular plug

Congenital portosystemic shunts (CPSS) may produce a variety of severe, clinically detrimental presentations. When indicated, closure is recommended; however, if the intrahepatic portal venous system (IPVS) is underdeveloped complete closure may not be possible and may result in severe acute portal hypertension. Staged restriction of CPSS flow by both surgical and complex transcatheter interventions has been successful in augmenting development of the IPVS such that complete occlusion of the CPSS can be performed. We report use of a modified microvascular plug to restrict CPSS flow with subsequent IPVS development and safe complete occlusion of CPSS.

Hot topics in interventional cardiology: Proceedings from the society for cardiovascular angiography and interventions 2020 think tank

The society for cardiovascular angiography and interventions (SCAI) think tank is a collaborative venture that brings together interventional cardiologists, administrative partners, and select members of the cardiovascular industry community for high-level field-wide discussions. The 2020 think tank was organized into four parallel sessions reflective of the field of interventional cardiology: (a) coronary intervention, (b) endovascular medicine, (c) structural heart disease, and (d) congenital heart disease (CHD). Each session was moderated by a senior content expert and co-moderated by a member of SCAI's emerging leader mentorship program. This document presents the proceedings to the wider cardiovascular community in order to enhance participation in this discussion, create additional dialogue from a broader base, and thereby aid SCAI and the industry community in developing specific action items to move these areas forward.

Outcomes of Transcatheter Tricuspid Valve-in-Valve Implantation in Patients With Ebstein Anomaly

We sought to describe the acute results and short- to medium-term durability of transcatheter tricuspid valve-in-valve (TVIV) implantation within surgical bioprostheses among patients with Ebstein anomaly (EA). Cases were identified from a voluntary, multicenter, international registry of 29 institutions that perform TVIV. Demographic, clinical, procedural, and follow-up data were analyzed. Eighty-one patients with EA underwent TVIV from 2008 to 2016. Thirty-four patients (42%) were New York Heart Association (NYHA) class 3/4 at time of TVIV. The most common indication for TVIV was the presence of moderate or severe tricuspid regurgitation (40%). Most patients received a Melody valve (64%). TVIV was ultimately successful in all patients, and there was no procedural mortality. Four patients (5%) developed acute valve thrombosis, 4 patients (5%) developed endocarditis, and 9 patients (11%) developed valve dysfunction not related to thrombosis or endocarditis. Eight patients (10%) underwent reintervention (2 transcatheter, 6 surgical) due to thrombosis (3), endocarditis (2), other valve dysfunction (2), and patient-prosthesis mismatch without valve dysfunction (1). Among 69 patients who were alive without reintervention at latest follow-up, 96% of those with NYHA status reported were class 1/2, a significant improvement from baseline (62% NYHA class 1/2, p <0.001). In conclusion, transcatheter TVIV offers a low-risk, minimally invasive alternative to surgical tricuspid valve re-replacement in patients with EA and a failing tricuspid valve bioprosthesis.

Diagnostic Utility of Three-Dimensional Rotational Angiography in Congenital Cardiac Catheterization

We evaluated the diagnostic utility of the three modalities of three-dimensional rotational angiography (3DRA): rotational angiography (RA), multiplanar reformat (MPR) and three-dimensional angiographic reconstruction (3D-R) in pediatric cardiac catheterization. The 3DRA studies were classified by anatomy of interest based on our injection protocol: pulmonary arteries (PA), aorta, cavopulmonary connection (CPC), and others. Retrospective review of 3DRA images by two reviewers for each modality was conducted with grading as inferior, similar, or superior in comparison with the diagnostic quality of fixed-plane angiography (FPA). The percentages of grades for each modality were averaged. Weighted kappa statistic was used to evaluate inter-rater reliability. In total, 114 3DRA studies were performed on 87 patients between August 2010 and March 2012. Median age was 2.7 years (1 day-48.4 years) and median weight 12.1 kg (3.6-106.5 kg). For RA: 79.4 % of the studies were of diagnostic quality and 52.2 % were superior; 3D-R: 82 % were of diagnostic quality and 65.8 % were superior; and MPR: 83.5 % were of diagnostic quality and 63 % were superior. Overall 3DRA technologies (RA, 3D-R, MPR) were of diagnostic quality or better in 111/114 (97.4 %) studies and 103/114 (90.4 %) were judged superior. Most common reasons for inferior grading were limited opacification and metallic artifact. In pediatric cardiac catheterization, 3DRA imaging was of diagnostic quality and frequently provided additional clinically relevant data when compared to FPA.

Feasibility and Safety of Using a Fused Echocardiography/Fluoroscopy Imaging System in Patients with Congenital Heart Disease

BACKGROUND

Fused real-time three-dimensional transesophageal echocardiography and fluoroscopy has been used in adult patients during percutaneous mitral valve and aortic valve procedures. The use of fused echocardiographic/x-ray fluoroscopic imaging (FEX) in pediatric patients undergoing congenital heart disease catheterization has not been evaluated for feasibility and safety. The aims of this study were to assess the feasibility and safety of FEX for interventional guidance and to perform a comparison of atrial septal defect (ASD) device closure using this technology with traditional guidance methods.

METHODS

Prospective evaluation of FEX in congenital cardiac interventions was conducted. A subset of patients with ASD closures were compared with patients with historical ASD closures with and without FEX. The interventionalist and echocardiographer rated the anatomic quality of the fusion imaging as (1) excellent, (2) good, or (3) poor. In addition, the utility of FEX procedural guidance was graded as (1) superior, (2) no added benefit, or (3) inferior to that of standard guidance by fluoroscopy and transesophageal echocardiography.

RESULTS

FEX was successfully used in 26 procedures on 25 patients with congenital heart disease from January 2013 to February 2015. The median age was 9 years (range, 3-26 years), and the median weight was 29 kg (range, 16-77 kg). Twenty-six procedures were performed, including ASD closure, Fontan fenestration closure, and transcatheter valve placement in the tricuspid valve position. There was reduced fluoroscopy time and radiation dose in patients with ASDs who underwent imaging using this new technology (P < .001 and P < .03, respectively). There were no statistically significant differences in procedural times between the two groups. Anatomic definition was rated as excellent in 20 of 26 procedures, with the remaining six rated was good. Twenty-one of 26 procedures were graded as superior (81%), and five of 26 (19%) were graded as providing no added benefit. There were no complications in any of the procedures.

CONCLUSIONS

In this early experience, FEX is feasible and safe in patients undergoing congenital heart disease catheterization and provides useful guidance in the majority of interventional procedures. There were relative reductions in fluoroscopy time and radiation dose with the use of FEX for ASD closure.

Transcatheter Tricuspid Valve-in-Valve Implantation for the Treatment of Dysfunctional Surgical Bioprosthetic Valves

Background—

Off-label use of transcatheter aortic and pulmonary valve prostheses for tricuspid valve-in-valve implantation (TVIV) within dysfunctional surgical tricuspid valve (TV) bioprostheses has been described in small reports.

Methods and Results—

An international, multicenter registry was developed to collect data on TVIV cases. Patient-related factors, procedural details and outcomes, and follow-up data were analyzed. Valve-in-ring or heterotopic TV implantation procedures were not included. Data were collected on 156 patients with bioprosthetic TV dysfunction who underwent catheterization with planned TVIV. The median age was 40 years, and 71% of patients were in New York Heart Association class III or IV. Among 152 patients in whom TVIV was attempted with a Melody (n=94) or Sapien (n=58) valve, implantation was successful in 150, with few serious complications. After TVIV, both the TV inflow gradient and tricuspid regurgitation grade improved significantly. During follow-up (median, 13.3 months), 22 patients died, 5 within 30 days; all 22 patients were in New York Heart Association class III or IV, and 9 were hospitalized before TVIV. There were 10 TV reinterventions, and 3 other patients had significant recurrent TV dysfunction. At follow-up, 77% of patients were in New York Heart Association class I or II ( P <0.001 versus before TVIV). Outcomes did not differ according to surgical valve size or TVIV valve type.

Conclusions—

TVIV with commercially available transcatheter prostheses is technically and clinically successful in patients of various ages across a wide range of valve size. Although preimplantation clinical status was associated with outcome, many patients in New York Heart Association class III or IV at baseline improved. TVIV should be considered a viable option for treatment of failing TV bioprostheses.

Hemodynamic response to ketamine in children with pulmonary hypertension

BACKGROUND

The safety of ketamine in children with pulmonary hypertension has been debated because of conflicting results of prior studies in which changes in mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) have been widely variable. The goal of this prospective study was to quantitate the effects of ketamine on pulmonary hemodynamics in a cohort of children with pulmonary hypertension under conditions in which variables such as airway/ventilatory management, FiO(2), and use of vasodilating anesthetics were controlled.

METHODS

The IRB approved this study of 34 children undergoing cardiac catheterization for pulmonary hypertension studies. Following anesthetic induction with sevoflurane and tracheal intubation facilitated by the administration of rocuronium 0.7-1 mg·kg(-1) iv, sevoflurane was discontinued and anesthesia was maintained with midazolam 0.1 mg·kg(-1) iv (or 0.5 mg·kg(-1) po preoperatively) and remifentanil iv infusion 0.5-0.7 mcg·kg(-1) ·min(-1). Ventilation was mechanically controlled to maintain PaCO(2) 35-40 mmHg. When endtidal sevoflurane was 0% and FiO(2) was 0.21, baseline heart rate (HR), mean arterial pressure (MAP), mPAP, right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic pressure (RVEDP), cardiac output, and arterial blood gases were measured, and indexed systemic vascular resistance (SVRI), indexed pulmonary vascular resistance (PVRI), and cardiac index (CI) were calculated. Each child then received a bolus of ketamine 2 mg·kg(-1) infused over 2 min. Measurements and calculations were repeated 2 min after the conclusion of the infusion.

RESULTS

The mean (95% CI) increase in mPAP following ketamine was 2 mmHg (0.2, 3.7), which was statistically significant but clinically insignificant. PVRI and PVRI/SVRI did not change significantly. Hemodynamic changes did not differ among subjects with differing severity of pulmonary hypertension or between subjects chronically treated with pulmonary vasodilators or not.

CONCLUSION

Ketamine is associated with minimal, clinically insignificant hemodynamic changes in sedated, mechanically ventilated children with pulmonary hypertension.

CRISP: Catheterization RISk score for Pediatrics: A Report from the Congenital Cardiac Interventional Study Consortium (CCISC)

OBJECTIVES

We sought to develop a scoring system that predicts the risk of serious adverse events (SAE's) for individual pediatric patients undergoing cardiac catheterization procedures.

BACKGROUND

Systematic assessment of risk of SAE in pediatric catheterization can be challenging in view of a wide variation in procedure and patient complexity as well as rapidly evolving technology.

METHODS

A 10 component scoring system was originally developed based on expert consensus and review of the existing literature. Data from an international multi-institutional catheterization registry (CCISC) between 2008 and 2013 were used to validate this scoring system. In addition we used multivariate methods to further refine the original risk score to improve its predictive power of SAE's.

RESULTS

Univariate analysis confirmed the strong correlation of each of the 10 components of the original risk score with SAE attributed to a pediatric cardiac catheterization (P < 0.001 for all variables). Multivariate analysis resulted in a modified risk score (CRISP) that corresponds to an increase in value of area under a receiver operating characteristic curve (AUC) from 0.715 to 0.741.

CONCLUSION

The CRISP score predicts risk of occurrence of an SAE for individual patients undergoing pediatric cardiac catheterization procedures.

Multimodality 3-dimensional image integration for congenital cardiac catheterization

Cardiac catheterization procedures for patients with congenital and structural heart disease are becoming more complex. New imaging strategies involving integration of 3-dimensional images from rotational angiography, magnetic resonance imaging (MRI), computerized tomography (CT), and transesophageal echocardiography (TEE) are employed to facilitate these procedures. We discuss the current use of these new 3D imaging technologies and their advantages and challenges when used to guide complex diagnostic and interventional catheterization procedures in patients with congenital heart disease.

Successful Treatment of Myocardial Infarction in an Infant With Kawasaki Disease

Although early treatment with intravenous immunoglobulin reduces the risk of coronary artery aneurysms, in refractory cases of Kawasaki disease, myocardial infarction can result from thrombosis of coronary artery aneurysms. Early recognition of myocardial infarction from Kawasaki disease myocarditis can reduce morbidity and mortality. This report describes successful treatment of myocardial infarction from coronary thrombosis in an infant with Kawasaki disease using intravenous tissue plasminogen activator and abciximab.

Standardizing radiation dose reporting in the pediatric cardiac catheterization laboratory-a multicenter study by the CCISC (Congenital Cardiovascular Interventional Study Consortium)

OBJECTIVES

We examine normalized air Kerma area product (PKA ) by body weight (PKA /BW) as a reference value of radiation dose and benchmark PKA /BW in pediatric laboratories using a multicenter registry database.

BACKGROUND

Reduction of radiation dose is an important quality improvement task in pediatric cardiac catheterization laboratories. Physicians need to agree on a standard method of reporting radiation dose that would allow comparisons to be made between operators and institutions.

METHODS

This was a multicenter observational study of radiation dose in pediatric laboratories. Patient demographic, procedural and radiation data including fluoroscopic time and PKA (µGy m(2) ) were analyzed. PKA /BW was obtained by indexing PKA to body weight.

RESULTS

A total of 8,267 pediatric catheterization procedures (age <18 years) were included from 16 institutions. The procedures consisted of diagnostic (n = 2,827), transplant right ventricular (RV) biopsy (n = 1,172), and interventional catheterizations (n = 4268). PKA correlated with body weight better than with age and best correlated with weight-fluoroscopic time product. PKA /BW showed consistent values across pediatric ages. Interventional catheterizations had the highest PKA /BW (50th, 75th, and 90th percentiles: 72, 151, and 281 μGy m(2) /kg), followed by diagnostic (59, 105, and 175 μGy m(2) /kg) and transplant RV biopsy (27, 79, and 114 μGy m(2) /kg).

CONCLUSION

PKA /BW appeared to be the most reliable standard to report radiation dose across all procedure types and patient age. We recommend PKA /BW to be used as the standard unit in documenting radiation usage in pediatric laboratories and can be used to evaluate strategies to lower radiation dosage in pediatric patients undergoing cardiac catheterizations. © 2014 Wiley Periodicals, Inc.

Aortoesophageal fistula and coarctation of the aorta in a 15-year-old child

Delayed presentation of coarctation of the aorta can be associated with severe complications. A challenging case of aortoenteric fistula secondary to an aneurysm from coartation of the aorta presented with massive gastrointestinal hemorrhage. The clinical management of this patient and a review of the literature are presented.

Cryo-balloon angioplasty for pulmonary vein stenosis in pediatric patients

This study sought to determine the safety and effectiveness of cryo-balloon angioplasty (CbA) for pulmonary vein stenosis (PVS) in pediatric patients. Current therapy options for PVS are less than satisfactory due to recurrent progressive restenosis and neointimal proliferation. Catheterization database, hospital records, imaging studies, and pathologic specimens were reviewed for procedural-related and outcomes data in all patients who underwent pulmonary vein (PV) CbA using the Boston Scientific PolarCath Peripheral Dilation System between August 2006 and June 2009. Thirteen patients (19 PVs; median age 13 months [range 3.5 months to 18.5 years] and weight 7.9 kg [range 3.8 to 47.7]) underwent CbA. Mean PVS diameter after CbA increased from 2.19 (± 0.6) to 3.77 (± 1.1) mm (p < 0.001). Mean gradient decreased from 14 (± 7.4) to 4.89 (± 3.2) mm Hg (p < 0.001). Mean stenosis-to-normal vein diameter ratio increased from 0.52 (± 0.15) to 0.89 (± 0.33) (p < 0.001). Eight patients underwent repeat catheterization a mean of 5.6 months (± 3.66) later. Improved PVS diameter was maintained in 2 PVs. Four veins had restenosis but maintained diameters greater than that before initial CbA. In 11 PVs, the diameter decreased from 4.28 (± 1.14) to 2.53 (± 0.9) mm (p = 0.001). Mean gradient increased from 3.55 (± 3.0) to 14.63 (± 9.6) mm Hg (p = 0.011). All vessels underwent repeat intervention with acute relief of PVS. Stroke occurred within 24 h of CbA in 1 patient. CbA of PVS is safe and results in acute relief of stenosis. However, CbA appears minimally effective as the sole therapy in maintaining long-term relief of PVS.

Potential role of three-dimensional rotational angiography and C-arm CT for valvular repair and implantation

Imaging modalities utilized in the interventional cardiology suite have seen an impressive evolution and expansion recently, particularly with regard to the recent interest in three-dimensional (3D) imaging. Despite this, the backbone of visualization in the catheterization laboratory remains two-dimensional (2D) X-ray fluoroscopy and cine-angiography. New imaging techniques under development, referred to as three-dimensional rotational angiography (RA) and C-arm CT, hold great promise for improving current device implantation and understanding of cardiovascular anatomy. This paper reviews the evolution of rotational angiography and advanced 3D X-ray imaging applications to interventional cardiology.

Left ventricular diastolic dysfunction in bronchopulmonary dysplasia

We report 2 infants with severe bronchopulmonary dysplasia in whom left ventricular diastolic dysfunction contributed to clinical abnormalities, including pulmonary hypertension and recurrent pulmonary edema. We speculate that close monitoring for left ventricular diastolic dysfunction may assist with clinical management and improve outcomes of infants with severe bronchopulmonary dysplasia.

Intermediate follow-up following intravascular stenting for treatment of coarctation of the aorta

BACKGROUND

We report a multiinstitutional study on intermediate-term outcome of intravascular stenting for treatment of coarctation of the aorta using integrated arch imaging (IAI) techniques.

METHODS AND RESULTS

Medical records of 578 patients from 17 institutions were reviewed. A total of 588 procedures were performed between May 1989 and Aug 2005. About 27% (160/588) procedures were followed up by further IAI of their aorta (MRI/CT/repeat cardiac catheterization) after initial stent procedures. Abnormal imaging studies included: the presence of dissection or aneurysm formation, stent fracture, or the presence of reobstruction within the stent (instent restenosis or significant intimal build-up within the stent). Forty-one abnormal imaging studies were reported in the intermediate follow-up at median 12 months (0.5-92 months). Smaller postintervention of the aorta (CoA) diameter and an increased persistent systolic pressure gradient were associated with encountering abnormal follow-up imaging studies. Aortic wall abnormalities included dissections (n = 5) and aneurysm (n = 13). The risk of encountering aortic wall abnormalities increased with larger percent increase in CoA diameter poststent implant, increasing balloon/coarc ratio, and performing prestent angioplasty. Stent restenosis was observed in 5/6 parts encountering stent fracture and neointimal buildup (n = 16). Small CoA diameter poststent implant and increased poststent residual pressure gradient increased the likelihood of encountering instent restenosis at intermediate follow-up.

CONCLUSIONS

Abnormalities were observed at intermediate follow-up following IS placement for treatment of native and recurrent coarctation of the aorta. Not exceeding a balloon:coarctation ratio of 3.5 and avoidance of prestent angioplasty decreased the likelihood of encountering an abnormal follow-up imaging study in patients undergoing intravascular stent placement for the treatment of coarctation of the aorta. We recommend IAI for all patients undergoing IS placement for treatment of CoA.

Procedural results and acute complications in stenting native and recurrent coarctation of the aorta in patients over 4 years of age: a multi-institutional study

BACKGROUND

We report a multi-institutional experience with intravascular stenting (IS) for treatment of coarctation of the aorta.

METHODS AND RESULTS

Data was collected retrospectively by review of medical records from 17 institutions. The data was broken down to prior to 2002 and after 2002 for further analysis. A total of 565 procedures were performed with a median age of 15 years (mean=18.1 years). Successful reduction in the post stent gradient (<20 mm Hg) or increase in post stent coarctation to descending aorta (DAo) ratio of >0.8 was achieved in 97.9% of procedures. There was significant improvement (P<0.01) in pre versus post stent coarctation dimensions (7.4 mm+/-3.0 mm vs. 14.3+/-3.2 mm), systolic gradient (31.6 mm Hg+/-16.0 mm Hg vs. 2.7 mm Hg+/-4.2 mm Hg) and ratio of the coarctation segment to the DAo (0.43+/-0.17 vs. 0.85+/-0.15). Acute complications were encountered in 81/565 (14.3%) procedures. There were two procedure related deaths. Aortic wall complications included: aneurysm formation (n=6), intimal tears (n=8), and dissections (n=9). The risk of aortic dissection increased significantly in patients over the age of 40 years. Technical complications included stent migration (n=28), and balloon rupture (n=13). Peripheral vascular complications included cerebral vascular accidents (CVA) (n=4), peripheral emboli (n=1), and significant access arterial injury (n=13). Older age was significantly associated with occurrence of CVAs. A significant decrease in the technical complication rate from 16.3% to 6.1% (P<0.001) was observed in procedures performed after January 2002.

CONCLUSIONS

Stent placement for coarctation of aorta is an effective treatment option, though it remains a technically challenging procedure. Technical and aortic complications have decreased over the past 3 years due to, in part, improvement in balloon and stent design. Improvement in our ability to assess aortic wall compliance is essential prior to placement of ISs in older patients with coarctation of the aorta.

The Genesis stent: A new low-profile stent for use in infants, children, and adults with congenital heart disease

Placement of intravascular stents that can reach adult size in infants and smaller children has been limited by the large profile and poor flexibility of currently available stents. In vitro and in vivo testing of the Genesis stent was performed to evaluate crimpability, predeployment flexibility, and radial strength. Comparisons were made to the Palmaz iliac and IntraStent (IS) LD stents. Nine physicians placed 30 Genesis stents in swine pulmonary and systemic arteries to evaluate stent deliverability/crimpability. Two swine were recovered and underwent a second catheterization 8 weeks later, where the stents (n = 8) were reexpanded to maximal size. Angiographic and intravascular ultrasound (IVUS) assessments were performed. In vitro testing revealed the Genesis stent to have superior crimpability, flexibility, and comparable radial strength to the Palmaz iliac stent, and superior crimpability and radial strength and comparable flexibility to the IS LD series. During in vivo testing, the physicians graded the Genesis stent superior to the Palmaz stent regarding crimpability and deliverability, and superior to the IS LD stent in regard to crimpability, and comparable to or superior in deliverability. In the chronic animals, the Genesis stent was expanded up to maximal diameter 8 weeks following implantation. Angiographic and IVUS revealed no fractures no in-stent restenosis. The Genesis stent can be easily delivered through smaller sheaths, which will facilitate their use in infants and smaller children with vascular stenosis.

Congenital heart disease in adults: catheterization laboratory considerations

Congenital heart defects are the most common birth defects and represent an increasing proportion of adolescent and adult patients followed by cardiologists. While many of these patients have undergone successful palliative or corrective surgery with excellent functional results, most of them still require careful follow-up. Further, even complex lesions may first be diagnosed in adolescence and adulthood. Therefore, cardiologists caring for adults need to become more familiar with these defects. Assessment of the patient with known or suspected congenital heart defects requires a careful history, physical examination, and noninvasive assessment. In addition, the catheterization laboratory remains a critical venue for diagnosis and, increasingly, therapy. Pressure measurements, oximetry, and angiography remain cornerstones of diagnosis in selected patients and a variety of interventional procedures have become viable therapeutic alternatives in both pre- and postoperative patients.

alpha(1)-Adrenoceptor-induced Mg2+ extrusion from rat hepatocytes occurs via Na(+)-dependent transport mechanism

The stimulation of the alpha(1)-adrenergic receptor by phenylephrine results in a sizable extrusion of Mg2+ from liver cells. Phenylephrine-induced Mg2+ extrusion is almost completely abolished by the removal of extracellular Ca2+ or in the presence of SKF-96365, an inhibitor of capacitative Ca2+ entry. In contrast, Mg2+ extrusion is only partially inhibited by the Ca2+-channel blockers verapamil, nifedipine, or (+)BAY-K8644. Furthermore, Mg2+ extrusion is almost completely prevented by TMB-8 (a cell-permeant inhibitor of the inositol trisphosphate receptor), 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (an intracellular Ca2+-chelating agent), or W-7 (a calmodulin inhibitor) Thapsigargin can mimic the effect of phenylephrine, and the coaddition of thapsigargin and phenylephrine does not result in an enlarged extrusion of Mg2+ from the hepatocytes. Regardless of the agonist used, Mg2+ extrusion is inhibited by >90% when hepatocytes are incubated in the presence of physiological Ca(2+) but in the absence of extracellular Na(+). Together, these data suggest that the stimulation of the hepatic alpha(1)-adrenergic receptor by phenylephrine results in an extrusion of Mg2+ through a Na(+)-dependent pathway and a Na(+)-independent pathway, both activated by changes in cellular Ca2+.

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.

Activation of Na(+)- and Ca(2+)-dependent Mg(2+) extrusion by alpha(1)- and beta-adrenergic agonists in rat liver cells

The administration of selective alpha(1) (phenylephrine)-, beta (isoproterenol)-, or mixed (epinephrine) adrenergic agonists induces a marked Mg(2+) extrusion from perfused rat livers. In the absence of extracellular Ca(2+), phenylephrine does not induce a detectable Mg(2+) extrusion, isoproterenol-induced Mg(2+) mobilization is unaffected, and epinephrine induces a net Mg(2+) extrusion that is lower than in the presence of extracellular Ca(2+) and quantitatively similar to that elicited by isoproterenol. In the absence of extracellular Na(+), no Mg(2+) is extruded from the liver irrespective of the agonist used. Similar results are observed in perfused livers stimulated by glucagon or 8-chloroadenosine 3', 5'-cyclic monophosphate. In the absence of extracellular Na(+) or Ca(2+), adrenergic-induced glucose extrusion from the liver is also markedly decreased. Together, these results indicate that liver cells extrude Mg(2+) primarily via a Na(+)-dependent mechanism. This extrusion pathway can be activated by the increase in cellular cAMP that follows the stimulation by glucagon or a specific beta-adrenergic receptor agonist or, alternatively, by the changes in cellular Ca(2+) induced by the stimulation of the alpha(1)-adrenoceptor. In addition, the stimulation of the alpha(1)-adrenoceptor appears to activate an auxiliary Ca(2+)-dependent Mg(2+) extrusion pathway. Finally, our data suggest that experimental conditions that affect Mg(2+) mobilization also interfere with glucose extrusion from liver cells.

Balloon aortic valvuloplasty in a 1,600-gram infant

We present a 1,600 g infant who underwent successful balloon aortic valvuloplasty from the right carotid artery approach. A simple technique to facilitate access to the left ventricle and expedite the procedure is described. Issues unique to performing balloon aortic valvuloplasty on such a small child are discussed.

Stenting of stenosed aortopulmonary collaterals and shunts for palliation of pulmonary atresia/ventricular septal defect

Patients with unrepaired pulmonary artery atresia and ventricular septal defect (PA/VSD) depend on aortoplumonary collaterals and surgically created shunts for pulmonary blood flow. These vessels frequently develop stenoses with time, leading to hypoperfusion of lung segments and systemic hypoxemia. The purpose of this article is to describe catheter palliation of hypoxemic patients with PA/VSD who were not candidates for surgical repair. We present our experience with stent implantation for stenosis of aortopulmonary collaterals and shunts in these patients. Three patients with hypoplastic pulmonary arteries underwent stent placement in aortopulmonary collateral arteries (APCAs) or their shunts. Technical aspects of the interventional catheterization procedure are discussed in detail. Case 1 underwent placement of five stents in collateral vessels and one stent in the Blalock-Taussig shunt (BT) with dramatic increase in vessel size and improvement in saturations from 70% to 89%. Case 2 underwent placement of two overlapping stents in a collateral vessel with an increase in diameter of the collateral vessel from 2.3 to 6 mm and an improvement in saturation from 68% to 88%. Case 3 underwent placement of three overlapping stents in a BT shunt with an increase in diameter of the shunt from 2.2 to 6.6 mm and an improvement in saturation from 71% to 89%. All three patients had excellent clinical improvement and stable saturation at follow-up. Stent placement for maintaining patency of APCAs and aortopulmonary shunts is feasible and safe.

Novel approach to transvenous pacemaker implantation in a post-fontan adolescent

Postoperative bradycardia is not uncommon following the Fontan procedure in patients with a functional single ventricle. The surgical connections created with various Fontan modifications may complicate access to the atria for transvenous implantation of a permanent pacemaker. We describe approaches to overcoming problems with atrial access in an adolescent with complex congenital heart disease who required permanent transvenous atrial pacing for tachycardia-bradycardia after Fontan surgery.