Iodixanol pharmacokinetics in children.

The objective of this report was to study the elimination pharmacokinetics of iodixanol in children. Iodixanol (Visipaque, Nycomed Inc., Wayne, PA, USA) is a new iso-osmolar iodinated radiocontrast agent. We hypothesized that elimination of this agent would be dependent on age-related differences in renal clearance. Seven centers enrolled 43 patients. Cardiac catheterization was performed in 41 patients and cranial computed tomography in 2. Patients were entered into 5 age groups: newborn to <2 months, 2 to <6 months, 6 months to <1 year, 1 to <3 years, and 3 to 6 months of age that is comparable to normal adults. Prolonged elimination in children <6 months of age is related to renal immaturity.

Access to the left atrium for delivery of radiofrequency ablation in young patients: retrograde aortic vs transseptal approach.

Reported experience with the transseptal approach to the left atrium for delivery of radiofrequency energy in the young patient is limited. To compare two approaches for radiofrequency ablation (RFA) in the left atrium we reviewed our experience from January 1, 1991, through February 1, 1999, in 154 procedures performed on 136 patients (mean age 12.2 years). The patients were grouped by either the retrograde aortic route (R, n = 30) or the transseptal atrial route (T, n = 106). No significant differences were found in age, weight, height, supraventricular tachycardia cycle length, or electrocardiograph characteristics (manifest vs concealed accessory pathway) between the two approaches. Comparison of the transseptal group to the retrograde aortic group revealed a significant difference in the number of catheters (mean = 4 R vs 3 T, p < 0.0001), total fluoroscopic time (71.3 min R vs 43.0 min T, p = 0.0007), diagnostic fluoroscopic time (40.2 min R vs 16.6 min T, p < 0.0001), ablation fluoroscopic time (44.7 min R vs 25.3 min T, p = 0.019), and procedure time (5.0 hours R vs 4.1 hours T, p < 0.0001). No significant difference was found in success rate, number of radiofrequency applications, or major complication rate. These data suggest that although outcomes and major complication rates are similar for the two groups, the use of fewer catheters and shorter fluoroscopic times warrant consideration of the transseptal atrial approach in young patients.

Inducibility of intra-atrial reentrant tachycardia after the first two stages of the Fontan sequence.

OBJECTIVES: We sought to examine the incidence and possible factors for inducible intra-atrial reentrant tachycardia (IART) in a group of patients after two stages of the Fontan sequence but before the operation. BACKGROUND: Intra-atrial reentrant tachycardia occurs in 10% to 40% of patients after the Fontan operation. No data are available regarding the potential for IART after the first two stages of the Fontan sequence but before the operation. METHODS: The IART induction protocol included programmed extrastimulation and rapid atrial pacing, with and without isoproterenol. RESULTS: The median age of the study group (n = 44, 27 males) was 1.7 years (range 1.2 to 5.2). Forty patients were in sinus rhythm. Twelve patients (27%) had inducible, sustained (>1 min) IART. Three patients (8%) had inducible, nonsustained IART. Bivariate analysis revealed that patients with sustained IART were significantly older at their second operation (median 0.54 vs. 0.40 years, p = 0.05). Multivariate logistic modeling revealed that older age (> or =0.55 years) at the second palliative operation (p = 0.04), older age (> or =1.95 years) at evaluation before the Fontan sequence (p = 0.04) and female gender (p = 0.03) were independently associated with sustained IART. A trend toward a greater frequency of sustained IART was seen in those patients with moderate or severe atrioventricular valve regurgitation (p = 0.07) and in those with resection of the atrial septum (p = 0.06). CONCLUSIONS: The rate of inducible, sustained IART in a group of patients before the Fontan operation is 27% and is associated with older age at the time of second-stage palliation, older age at pre-Fontan evaluation and female gender.

Transcatheter closure of fontan fenestrations using the Amplatzer septal occluder: initial experience and follow-up.

We have recently used the Amplatzer septal occluder to close Fontan fenestrations. Between June 1998 and December 1999, 13 patients underwent transcatheter occlusion of their Fontan fenestrations. Systemic blood flow decreased significantly without a concomitant decrease in pulmonary blood flow. All residual shunts detectable by oximetry were at sites separate from those into which occlusion devices were implanted. One patient developed severe tricuspid regurgitation following the procedure requiring surgical removal of the device. At the last follow-up, all patients were doing well clinically. There were no shunts detectable through or around the devices by echocardiography. Our experience indicates that the location of the fenestration within the Fontan baffle is critical to avoiding device interference with other intracardiac structures. The Amplatzer septal occluder offers an effective means of transcatheter closure of Fontan baffle fenestrations. Although more experience is needed, our current follow-up data suggest that long-term outcomes will be favorable. Cathet. Cardiovasc. Intervent. 51:301-304, 2000.

Coil occlusion of a femoral arteriovenous fistula.

A femoral arteriovenous fistula was discovered in a 17-mo-old child with congenital heart disease and prior femoral cardiac catheterization. The fistulous connection was clearly visible by angiography with vein compression, and the fistula was closed percutaneously using a Gianturco coil. Cathet. Cardiovasc. Intervent. 51:308-311, 2000.

Results of transvenous occlusion of secundum atrial septal defects with the fourth generation buttoned device: comparison with first, second and third generation devices. International Buttoned Device Trial Group.

OBJECTIVES: The purpose of this study was to assess safety and effectiveness of the fourth generation buttoned device in dosing atrial septal defects (ASDs) and to test the hypothesis that introduction of double button reduces unbuttoning rate without reducing effectiveness. BACKGROUND: Because of the high unbuttoning rate (7.2%) with first, second and third generation buttoned devices, the device was modified (fourth generation) so that there were two radiopaque spring buttons 4 mm apart on the button loop attached to the occluder. METHODS: During a four-year period ending in September 1997, 423 patients, ages 1.5 to 80 years (median 16 years), underwent closure of ASD at 40 medical centers around the world. RESULTS: The ASD size varied between 5 and 30 mm (median 17 mm). The device size varied between 25 and 60 mm. Unbuttoning occurred in 4 (0.9%) of 423 patients. Effective occlusion, defined as no (n = 343) or trivial (n = 34) residual shunt on echo-Doppler studies performed within 24 h of the procedure, was demonstrated in 377 patients (90%). Thus, the unbuttoning rate (0.9 vs. 7.2%) decreased (p<0.01) while effective occlusion rate (90 vs. 92%) remained unchanged (p>0.1) with this device, compared with earlier generation devices. During follow-up from one month to five years (23+/-15 months), 21 (5%) of 417 patients required surgical (n = 12) or transcatheter (n = 9) reintervention, mostly to treat significant residual shunt. In the remaining patients there was gradual reduction and disappearance of the residual shunt. No wire integrity problems were observed. CONCLUSIONS: These data suggest that the fourth generation buttoned device is as effective as earlier generation devices, but without significant unbuttoning. Follow-up results remained good, with a reintervention-free rate of 89% at five years.

Interventional cardiac catheterization advances in nonsurgical approaches to congenital heart disease.

Interventional cardiac catheterization offers increased therapeutic options to many patients with congenital heart disease. Over the past year encouraging results have been reported in hundreds of patients with interatrial communications, patent ductus arteriosus, and pulmonary artery stenosis requiring stenting. The Amplatzer (AGA Medical Corporation, Golden Valley, MN, USA) family of atrial septal, ventricular septal, and ductus occluding devices shows particular promise. Other studies support the efficacy and safety of established procedures such as balloon valvuloplasty and coarctation angioplasty. In some areas, such as transcatheter perforation of atretic pulmonary valves and endovascular stenting for coarctation of the aorta, our technical abilities may be advancing faster than our understanding of the ultimate clinical impact of our treatment. As interventional cardiac catheterization procedures continue to develop, they must be evaluated carefully against alternative treatments.

Snare-assisted vascular access: a new technique.

Access to the central circulation can be difficult in small infants, particularly when normal anatomic landmarks have been altered. We describe a new technique that utilizes any existing central catheter to establish additional sites of vascular access. A 4 Fr end hole catheter is advanced under fluoroscopic guidance to the desired site of new vascular access. A 10-mm Amplatz snare catheter is advanced through the end hole catheter and the loop opened within the target vessel lumen. The snare is then used to guide percutaneous placement of a Cope wire through a 21-gauge needle and then to pull the wire into the central circulation. New access is then achieved by introducing an additional catheter over the guidewire. This technique has now been successfully utilized 16 times in 13 patients. Snare assistance is a safe and effective technique that provides a reliable means of establishing additional secure vascular access. Cathet. Cardiovasc. Intervent. 47:315-318, 1999.

Transhepatic therapeutic cardiac catheterization: a new option for the pediatric interventionalist.

We evaluate the efficacy and safety of percutaneous transhepatic (TH) venous access for interventional cardiac catheterization. A retrospective review of all TH therapeutic catheterizations between January 1994 and September 1998 was performed. Patient demographics, pre- and postcatheterization hemoglobin and liver function studies, and complications were evaluated. TH access was performed for 30 interventional catheterizations in 25 patients with a median age of 39 months (range, 1 day to 41 years) and weight of 13.2 kg (3.1-87.0 kg). Indications for TH access were bilateral obstructed femoral veins (n = 15), obstructed femoral veins and superior vena cava (n = 3), Greenfield filter (n = 2), and presumptive improved route for intervention via TH access (n = 5). TH interventions were successful in 29/30 procedures (97%). Interventions via TH sheath sizes of 4-14 Fr included pulmonary angioplasty +/- stent (n = 11), radiofrequency ablation (n = 4), atrial septal defect device occlusion (n = 2), coil occlusion of pulmonary artery pseduoaneurysm (n = 2), Fontan fenestration device occlusion (n = 2), pulmonary valvuloplasty (n = 2), stent dilation of the superior vena cava (n = 2), and one each of device retrieval, Fontan baffle stent placement and subsequent redilation, Fontan fenestration dilation, transseptal mitral valvuloplasty, and cardiac biopsy. There were no changes in pre- and post-TH hemoglobin levels (mean +/- SD, 12.9+/-2.2 vs. 11.9+/-1.9 gm/dL; P = NS) or alanine transferase (34.0+/-27.5 vs. 43.4+/-18.2 IU/L; P = NS). One patient developed important intraperitoneal bleeding and required exploratory laporatomy. Percutaneous TH access is safe and effective as a route for interventional catheter procedures for patients with limited venous access.

Utility of cardiac catheterization in pediatric cardiac patients on ECMO.

Cardiac catheterization has been utilized rarely in children on extracorporeal membrane oxygenation (ECMO). We performed a retrospective review of 15 children with congenital heart disease who had undergone catheterization while on ECMO from December 1990-December 1995. The procedures, including four interventions, were successful in all patients with adequate evaluation of clinical questions. Unexpected diagnostic information of clinical importance was obtained in 40%, and clinical management of patients was significantly altered in 73%. All patients tolerated the procedure and transport well. The only significant complication was a retroperitoneal hemorrhage in one patient after approximately 12 hr. Although no patients died at catheterization, overall survival was poor, with 50% weaning from ECMO, 29% surviving to discharge, and 14% surviving at follow-up. We conclude that diagnostic and interventional catheterization may be performed in patients on ECMO with acceptable morbidity and mortality; however, long-term survival in this population is poor.

The effect of a right-to-left intracardiac shunt on the rate of rise of arterial and end-tidal halothane in children.

UNLABELLED: In this prospective study, we evaluated the effect of a right-to-left intracardiac shunt on the rate of rise of end-tidal and arterial halothane concentration in children. Six children aged 23-43 mo undergoing surgical closure of atrial fenestration after Fontan procedure were given 0.8% inspired halothane. End-tidal halothane was recorded at 1-min intervals after the introduction of halothane. Arterial halothane concentrations were determined 0, 1, 3, 5, 10, and 15 min after the introduction of halothane. The sampling was performed before and after closure of the atrial fenestration. The ratio of pulmonary to systemic blood flow (Qp/Qs) increased in this patient population, from 0.58 +/- 0.04 to 0.88 +/- 0.12 (P = 0.01). The rate of rise of end-tidal halothane did not change significantly with a decrease in the magnitude of the right-to-left intracardiac shunt after closure of the atrial fenestration. The ratio of arterial to inspired halothane concentrations at 1, 3, 5, 10, and 15 min were lower before closure of the atrial fenestration compared with after closure (P < 0.05). We conclude that the presence of a right-to-left intracardiac shunt significantly slows the rate of rise of arterial halothane in the face of a constant inspired concentration. The rate of rise of end-tidal halothane is not significantly affected in the presence of a right-to-left intracardiac shunt. IMPLICATIONS: In this prospective study, we found a slower rate of rise of halothane in arterial blood in children with right-to-left intracardiac shunting. Induction of anesthesia by inhalation of volatile anesthetics may therefore be slower in these children.

Neonatal cardiac catheterization: A 10-year transition from diagnosis to therapy.

To assess the changing role of cardiac catheterization in the care of the neonate, a retrospective review of all catheterizations between January 1984 to December 1985 (group I) and January 1994 to December 1995 (group II) at C.S. Mott Children's Hospital was performed. Neonatal cardiac catheterization was performed more frequently (p = 0.02) in group I, comprising 14% (110 of 772) of all catheterizations versus 11% (93 of 880) in group II. Access was performed by cutdown in 15 patients (13 venous and 2 arterial), all in group I. In group I, 20 of 110 patients (18%) had balloon atrial septostomies; no other catheter interventions were performed. Interventions were more frequent (p = 0.003) and varied in group II, including 15 septostomies, 17 balloon valvuloplasties (13 pulmonary and 4 aortic), 2 coil embolizations of collaterals, and 1 cardiac biopsy. Despite the higher prevalence and complexity of interventions in group II, fluoroscopy times (median; range: 16 min; 2-55 vs 16 min; 1-107) were similar in both groups (p = not significant) as well as the prevalence of complications. Neonatal cardiac catheterizations are performed less frequently than they were a decade ago at our institution, and therapeutic interventions have become more common. Despite these changes, fluoroscopy time and the rate of complications have not increased.

Late fenestration closure in the hypoplastic left heart syndrome: comparison of hemodynamic changes.

BACKGROUND AND OBJECTIVES: Although survival of patients with the hypoplastic left heart syndrome treated by staged surgical palliation has improved, hemodynamic data after fenestrated Fontan operation and after fenestration closure have not been reported in this patient population. We sought to describe the hemodynamic status of these patients at cardiac catheterization performed for the purpose of fenestration closure and to compare these data with data from contemporary patients with other forms of univentricular heart. METHODS AND RESULTS: Hemodynamic responses to fenestration closure during cardiac catheterization were reviewed in 40 consecutive patients, including 20 with the hypoplastic left heart syndrome and 20 with other forms of univentricular heart defects. Hemodynamics before fenestration closure (arterial saturation and pressure, Fontan baffle saturation and pressure, pulmonary capillary wedge pressure, systemic arteriovenous oxygen content difference, and right-to-left shunt fraction) were nearly identical between the two groups. Significant (p < 0.05) changes after fenestration closure included increases in arterial saturation (9%), mean arterial pressure (3 mm Hg), and baffle pressure (1 mm Hg) and arteriovenous oxygen content difference (18 ml/L), with near elimination of right-to-left shunting. Cardiac output decreased by 21% and systemic oxygen transport by 13%, with no differences between the two patient groups. Mean baffle pressures were <17 mm Hg in 32 patients (80%). CONCLUSIONS: Hemodynamics after fenestrated Fontan operation and responses to fenestration closure in patients with the hypoplastic left heart syndrome were remarkably similar to that in patients with other univentricular heart defects.

Intermediate-term results of Phase I Food and Drug Administration Trials of buttoned device occlusion of secundum atrial septal defects.

OBJECTIVES: This study was conducted to evaluate the intermediate-term results of the multi-institutional U.S. trial of the buttoned device for transcatheter closure of atrial septal defects (ASDs). BACKGROUND: The trial was conducted in three centers (University of Arizona, University of Michigan and University of Wisconsin) under a Food and Drug Administration (FDA)-approved clinical trial with investigational device exemption. Only short-term follow-up is known. METHODS: All 46 patients who had successful implantation of the device were prospectively followed up. Patients were evaluated at 1, 6 and 12 months after device occlusion and yearly thereafter. RESULTS: This cohort was followed up from 51 to 68 months (mean 60.8, median 62). Patient ages ranged from 1 to 62 years (median 4); weights ranged from 10 to 105 kg (median 18); and stretched ASD sizes were 14 +/- 4 mm (left to right shunts) and 10 +/- 3 mm (right to left shunts). Of the 46 patients, 45 (98%) had effective occlusion of their ASD, and 34 (74%) had complete ASD closure. The incidence of residual shunts decreased from 65% (30 of 46 patients) at 1 month after device placement to 27% (12 of 45 patients) at last follow-up. All residual shunts were quantitated as trivial. Only two patients (4%) required reintervention for significant residual defects. There were no cases of endocarditis or thromboembolism in 224 patient-years of follow-up. CONCLUSIONS: In up to 5.5 years of follow-up, the buttoned device provided effective closure in 98% of patients in whom the device was successfully implanted. The incidence of residual shunts decreased during follow-up, and no instances of endocarditis or thromboembolism were observed.

Transhepatic access to the atrioventricular ring for delivery of radiofrequency energy.

INTRODUCTION: Transcatheter radiofrequency ablation is an effective, safe treatment of arrhythmias in children. However, despite technical advances, patients with obstructed venous access to the heart have not been candidates for this treatment. METHODS AND RESULTS: Two children (8.2 and 10.9 kg) with complex congenital heart disease, supraventricular tachycardia, and obstructed venous access underwent successful radiofrequency ablation of either a right (one patient) or left (one patient) accessory pathway using the transhepatic route to the heart. CONCLUSION: This experience underscores the usefulness of the transhepatic approach in small patients, in patients with limited venous access, and in patients with complex congenital heart disease.

Usefulness of repeat balloon aortic valvuloplasty in children.

This retrospective study examines all 15 patients who underwent a second balloon dilation procedure for congenital aortic stenosis to determine its safety and efficacy. The recurrent gradient was significantly reduced, but 4 patients had unsatisfactory gradient relief, 3 of whom had previous surgical valvotomies; therefore, we conclude that repeat balloon aortic valvuloplasty is worthwhile, although third balloon dilations may not be beneficial.

Comparison of hospital charges for balloon angioplasty and surgical repair in children with native coarctation of the aorta.

A retrospective review of hospital charges was performed in children > 1 year old with native coarctation of the aorta who underwent balloon angioplasty, primary surgical repair, or elective surgical repair after unsuccessful balloon angioplasty. Hospital charges were less overall in the balloon angioplasty group, although the failure rate was higher.

Acute results of balloon angioplasty of native coarctation versus recurrent aortic obstruction are equivalent. Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry Investigators.

OBJECTIVES: This study sought to compare the immediate results and risk factors for suboptimal outcomes of percutaneous balloon angioplasty for native versus recurrent aortic obstruction. BACKGROUND: Some cardiology centers have been reluctant to adopt balloon angioplasty for treatment of native aortic coarctation, while advocating balloon angioplasty over an operation for treatment of postsurgical or recurrent aortic obstruction. METHODS: Acute results were analyzed from 970 procedures (422 native and 548 recurrent lesions) performed between 1982 and 1995 in 907 patients from 25 centers. An acute suboptimal outcome was defined as one or more of the following: residual systolic pressure gradient > or = 20 mm Hg, residual proximal to distal systolic pressure ration > or = 1.33 or a major complication (death, aortic transmural tear, stroke). RESULTS: Bal loon angioplasty significantly (p = 0.0001) increased lesion diameter fo r both native (mean [+/= SD] 128 +/= 94%) and recurrent aortic obstruction (97 +/= 87%), with a significantly greater increase in the native group (p = 0.0001). A reduction in systolic pressure gradients was significant in both groups (p = 0.0001), but slightly higher (p = 0.01) for native (-74 +/- 24%) versus recurrent obstruction (-70 +/- 31%). Death associated with angioplasty was reported in 0.7% of patients with native and in 0.7% of patients with recurrent lesions (p = 1.00). An acute suboptimal outcome was noted with angioplasty in 19% of native and in 25% of recurrent lesions (p = 0.04). Significant independent risk factors included higher preangioplasty systolic gradient (odds ratio [OR] 1.39/10-mm Hg increment; 95% confidence interval [CI] 1.28 to 1.50, p = 0.0001), earlier study date (OR 0.92/1-year increment, 95% CI 1.02 to 1.26, p = 0.02) and recurrent obstruction (OR 1.39 vs. native lesions, 95% CI 1.00 to 1.94, p = 0.05). CONCLUSIONS: Acute results and complications of balloon angioplasty of native coarctation appear to be equivalent or slightly superior to those of recurrent aortic obstructions.