Flip Coil Research Articles

Dynamic fringe field effects of the rapid ramping quadrupole magnets at the Rapid Cycling Synchrotron of China Spallation Neutron Source

The dynamic fringe field of the quadruple magnets at the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS) was measured and studied using a small flip coil measurement system. For DC quadruple magnets, the normalized magnetic field distribution along the beam trajectory, which is determined by the mechanical structure of the magnet, is independent of the exciting current. However, the magnetic field measurement results at CSNS-RCS showed that the normalized magnetic field distribution along the beam trajectory varies during the exciting current ramping process for quadruple magnets. The variation of the normalized magnetic field distribution can induce a time-dependent tune during the ramping process. Therefore, in this paper, we analyzed and studied the dynamic fringe field effects of the rapid ramping quadrupole magnets at CSNS-RCS.

Development of the high energy engineering X-ray (HEX) superconducting wiggler, magnetic measurement, installation, and commissioning.

The High energy Engineering X-ray (HEX) diffraction beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Lab (BNL) is the first high-energy beamline capable of reaching 200keV for a monochromatic beam. With the 3 GeV electron beam energy for the NSLS-II ring, only the superconducting wiggler (SCW) producing greater than 4T peak field can cover these ranges with a sufficient number of photons. The 1.2 m-long HEX-SCW has a period length of 70mm and a field strength on-axis of 4.3T. It utilizes no liquid helium, and the vertical aperture size of the electron beam vacuum chamber is 8mm. Unlike regular undulators/wigglers, there is no standard configuration for the magnetic measurement system for superconducting insertion devices. The NSLS-II Insertion Devices group has developed, in collaboration with the vacuum group, a novel in-vacuum Hall mapper with a 1.75m in-vacuum linear motor and an in-vacuum flip coil system utilizing many commercial-off-the-shelf products. The measurements were conducted at the BNL, and the device was installed in the ring and commissioned. This paper provides a description of the SCW and its magnetic measurement systems, as well as a brief account of the installation and commissioning efforts.

AC magnetic field measurement using a small flip coil system for rapid cycling AC magnets at the China Spallation Neutron Source (CSNS)

The China Spallation Neutron Source (CSNS) has two major accelerator systems, a linear accelerator and a rapid cycling synchrotron (RCS). The RCS accelerator is used to accumulate and accelerate protons from the energy of 80 MeV to the design energy of 1.6 GeV at the repetition rate of 25 Hz, and extract the high energy beam to the target. The main magnets of the RCS accelerator are excited by AC current with DC bias. The magnetic field quality is very important for the RCS accelerator operation, since it should guarantee and focus a circulating beam. In order to characterize the AC magnets, a small flip coil measurement system has been developed and one of each type of AC magnets has been studied. The measurement system and selected measurement results are presented in this paper.

Transcatheter closure of patent ductus arteriosus using Flipper coil and Amplatzer Duct Occluder: Ten-year experience from a single center

Introduction/Objective. Transcatheter closure is a well-established procedure for treatment of patent ductus arteriosus (PDA). We aimed to make a comparison between transcatheter PDA occlusion with Flipper coil and Amplatzer Duct Occluder (ADO) and to determine the incidence and significance of procedural complications. Methods. Between November 2004 and October 2014, 148 patients were eligible for transcatheter PDA closure at the University Children?s Hospital in Belgrade, Serbia. The median age was 5.9 years (the range of 0.9 years to 17.3 years) and the median weight was 21 kg (the range of 8.8 kg to 94 kg). Follow-up evaluations with Doppler echocardiogram were performed at one day, three months, and one and two years after the PDA occlusion. Results. Median narrowest PDA diameter was 1.5 mm (the range of 0.5 mm to 5.6 mm). Flipper coil was used for PDA closure in 84 (59.2%) and ADO in 58 patients (40.8%). There was no significant difference in the rate of immediate complete closure between the coil and the ADO group (86.9% vs. 75.9%, p = 0.089), but a significantly higher rate of complete closure was achieved with ADO at one day (83.3% vs. 98.3%, p = 0.004), three months (85.7% vs. 100%, p = 0.002), and both one and two years after the implantation (91.7% vs. 100%, p = 0.041). In total, 12 complications occurred during the procedure, seven of which with coil and five with ADO occlusion of PDA. Conclusion. Transcatheter closure of PDA using both coils and ADOs is a very safe and effective procedure. ADO proved superior to coil in terms of complete closure rate as early as one day after the procedure.

Dynamic Field Integrals in Taiwan Photon Source Undulators

In an insertion device, the electrons wiggle with finite amplitudes because of the periodic magnetic field. The field integral is contributed from the static field integrals of construction field errors and intrinsic dynamic field integrals. From a flip coil or stretched wire, it is impossible to obtain a true integrated field along the electron trajectory. The dynamic field integral is derived from the nonuniformity in the transverse distribution of the magnetic field. The influence of the dynamic field integral on the spectral broadening of undulator radiation and the tune shift due to oscillation of the beam might produce a degraded performance of an undulator or a storage ring. In this paper, the tune shifts and spectral broadening of two Taiwan Photon Source undulators, an in-vacuum undulator and an elliptically polarized undulator, are discussed based on dynamic field integrals.

Field measurement facility for the PAL-XFEL undulator

The Pohang Accelerator Laboratory (PAL) is developing a self amplification of spontaneous emission (SASE) based free electron laser (FEL) for X-ray coherent photon sources. The PAL developed a prototype undulator that had a 5.0 m magnetic length and a 7.2 mm minimum gap at a magnetic field of ∼0.908 T. The PAL has constructed an undulator field measurement facility to confirm the field qualities of the X-ray free electron laser (XFEL) undulators in the assembly building. Two field measurement benches which included a Hall probe scanner, a flip coil and a stretched wire system were installed and their performances were evaluated. This paper describes the field measurement facility and presents the performance test results of the two benches.

Transcatheter patent ductus arteriosus closure with echocardiographic guidance: can radiation exposure be reduced?

The radiation dose from interventional cardiac catheterization is particularly relevant when treating children because of their greater radiosensitivity compared to adults. The transcatheter closure of patent ductus arteriosus (PDA), as well as other more complex pediatric interventions, have raised concerns regarding radiation exposure, particularly relevant when treating children. The purpose of this study is to show how to perform the transcatheter closure of PDA in children while giving less ionized radiation and to prove that the amount of radiation and contrast material can be reduced. Following appropriate device selection based on PDA morphology and diameter, transthorasic echocardiography images and control aortography findings were analyzed. The following devices were used during the procedure: Gianturco coils (10/63), an Amplatzer Duct Occluder (ADO, 31/63), Flipper coils (19/63), and an Amplatzer vascular plug (3/63). The scopy time, radiation dose, and contrast were 12 ± 6.4 mins, 28.1 ± 14.7 cmGy/cm²/kg, and 4.2 ± 2.3 cc/kg, respectively. In the control aortography shortly after the procedure, residual shunt was detected at various levels in 39.7% of patients, and 9.5% demonstrated residual shunt in real-time echocardiography. In the control aortography, the exposure to radiation was 13.3% of the total, and the amount of infused contrast was 27.2% of the total. Patients may be exposed to less radiation and contrast material if an echocardiographic evaluation, instead of a final control aortography injection, is performed after the transcatheter closure of PDA.

ADC's Insertion Devices and Magnetic Measurement Systems Capabilities

In this paper Advance Design Consulting USA, Inc. (ADC) will discuss ADC's major improved capabilities for building Wiggler Insertion Devices, Undulator Planar Devices, Elliptical Polarizing Undulators (EPU), In-Vacuum Undulators (IVU), Cryogenically Cooled in-vacuum Undulators (CPMU), Super Conductive Undulator, and Insertion Device Magnetic Measurement Systems. ADC has designed, built and delivered Insertion Devices and Magnetic Measurement Systems to such facilities as MAX-lab (two EPUs, a Planar, and Measurement System), ALBA and ASP (Wigglers), BNL (CPMU), SSRF (two IVUs and a Measurement System), PAL (one IVU and Measurement System), NSRRC (one 4m EPU), and SRC (Planar and EPU). ADC's magnetic field measurement system is a sophisticated and sensitive machine for the measurement of magnetic fields in undulators (Planar and EPU), wigglers and in-vacuum ID units. The magnetic fields are measured using 3 axis hall-effect probes, mounted orthogonally, to a thin wand. The wand is mounted to a carriage that rides on vacuum air bearings. The base is granite. A flip coil is provided on two vertical towers with X, Y and Theta axes. Special software is provided to assist in homing, movement, and data collection and analysis.

Aspectos particulares da oclusão percutânea do canal arterial do adulto

INTRODUÇÃO: A oclusão percutânea do canal arterial é um método seguro, eficaz e facilmente reproduzível. O canal arterial do adulto pode apresentar alterações degenerativas, que aumentam o risco da cirurgia e favorecem o procedimento percutâneo. Descrevemos a experiência de um centro único com a oclusão percutânea do canal arterial em adultos e destacamos aspectos técnicos particulares desse procedimento. MÉTODOS: Revisamos os registros de todos os pacientes > 20 anos de idade submetidos a oclusão do canal arterial entre março de 2001 e dezembro de 2012. Os casos foram selecionados por ecocardiografia transtorácica. RESULTADOS: Analisamos 33 pacientes, a maioria do sexo feminino (72,7%), com médias de idade de 30,9 ± 12,8 anos e de peso de 63,9 ± 12,4 kg. Somente 3 pacientes tinham sintomas e 2 pacientes apresentaram defeitos associados, tratados no mesmo procedimento. Os implantes foram possíveis em todos os casos. Foram utilizadas 1 mola Flipper, 19 próteses AmplatzerTM Duct Occluder tipo I, 3 próteses AmplatzerTM Duct Occluder tipo II, 8 próteses CeraTM PDA Occluder e 2 próteses para comunicação interventricular muscular. O uso de balões medidores foi necessário em 5 casos. O seguimento médio foi de 46,1 ± 42,9 meses e foi obtido em 84,9% dos pacientes. Dois casos apresentaram shunt residual imediatamente após o procedimento. Não ocorreram complicações maiores ou óbitos. CONCLUSÕES: A oclusão percutânea dos canais dos adultos com os dispositivos empregados pode ser realizada com segurança e eficácia.

Transcatheter Closure of the Patent Ductus Arteriosus: An Intention to Treat Analysis

In patients with patent ductus arteriosus (PDA), transcatheter closure is the current procedure of choice. There are multiple devices available with limited current comparative data and varied recommendations for device selection. To assess the efficacy and safety of the Flipper coil (FC) and the Amplatzer Duct Occluder (ADO). An intention to treat analysis of all children admitted to the catheter laboratory at a single institution for occlusion of PDA from 2003 to 2011 was performed. Patient and device selection were determined by the treating physician. Standard techniques for FC and ADO implantation were used. Two hundred and twenty eight children with median weight of 14.2 kg (range; 5.5-68 kg) underwent cardiac catheterisation, with successful occlusion in 96.2% of patients when attempted. In 16 patients, median angiographic PDA diameter of 0.8 mm (range; 0.4-1.2 mm), was considered too small to warrant closure. Eight patients with large PDA's underwent surgical ligation. FC was successfully used in 70 (34.3%) and ADO in 134 (66.7%) patients. ADO patients were smaller (P=0.004) with larger PDA's (P<0.0001) than the FC group. Median fluoroscopy time was longer for ADO patients (10.1 min vs 8.0 min; P<0.0001). ADO had a lower embolisation rate (0% vs 6.6%; P=0.005) and a higher complete occlusion rate at follow-up (100% vs 73.4%; P<0.0001). Length of hospital admission decreased with time in both groups. Transcatheter closure of the PDA has a high degree of safety and efficacy. This study suggests that the ADO may be the device of first choice in the current era.

Comparison of the results of transcatheter closure of patent ductus arteriosus with newer amplatzer devices

To compare the success and complication rates for the different devices and patent ductus arteriosus (PDA) types. There are numerous devices available for transcatheter closure of PDA but data comparing the success and complication rates of the newer devices are lacking. A retrospective review was undertaken of all cases of transcatheter PDA closure at a tertiary referral center. Transcatheter PDA closure was achieved in 176 of 177 cases. Mean age, weight, and minimum ductal diameter were 3.3 years, 15.0 kg, and 2.5 mm, respectively. Devices used were Amplatzer Duct Occluder I (ADO I, 50.3%), Amplatzer Duct Occluder II (ADO II, 28.2%), Amplatzer Duct Occluder II Additional Sizes (ADO II AS, 5.1%), flipper coils (14.1%), and "other" devices (2.3%). Regarding Amplatzer devices, arterial delivery had a significantly shorter fluoroscopy time as compared to venous delivery (3.7 vs. 5.0 min, P = 0.0068), with no significant difference in outcomes. Immediate residual shunt rates were 7.9% (7/89) for ADO I, 4.1% (2/49) for ADO II, 11.1% (1/9) for ADO II AS, and 0% (0/25) for flipper coils. Aortic protrusion rates were 9% (8/89) for ADO I, 14.3% (7/49) for ADO II, and O% for both ADO II AS (0/9) and flipper coils (0/25). All devices achieved excellent occlusion rates with low complication rates, regardless of PDA type. Device delivery via arterial access was associated with a shorter fluoroscopy time as compared to venous delivery, with no significant difference in outcomes. ADO II AS may be preferable to ADO II in the younger infant.

Specific Aspects of Percutaneous Closure of Patent Ductus Arteriosus in Adult Patients

ABSTRACT Background Percutaneous closure of patent ductus arteriosus is a safe, effective and easily reproducible method. Adult patent ductus arteriosus may present degenerative changes that increase surgical risk and favor percutaneous closure. We report a single center experience with percutaneous closure of patent ductus arteriosus in adults and highlight specific technical aspects of this procedure. Methods The records of patients ≥ 20 years of age submitted to patent ductus arteriosus closure between March 2001 and December 2012 were evaluated. Cases were selected by transthoracic echocardiography. Results We analyzed 33 patients, most of them females (72.7%), with mean age of 30.9 ± 12.8 years and weight of 63.9 ± 12.4 kg. Only 3 patients had symptoms and 2 had associated congenital defects, treated in the same procedure. Implants were possible in all cases. One Flipper Coil, 19 Amplatzer™ Duct Occluders type I, 3 Amplatzer™ Duct Occluders type II, 8 Cera™ PDA Occluders and 2 Muscular VSD devices were used. Sizing balloons were used in 5 cases. Mean follow-up was 46.1 ± 42.9 months and was obtained in 84.9% of patients. Two cases presented residual shunts immediately after the procedure. There were no major complications or deaths. Conclusions Percutaneous closure of adult patent ductus arteriosus may be performed safely and effectively with the devices used in this study.

Two-dimensional radial sodium heart MRI using variable-rate selective excitation and retrospective electrocardiogram gating with golden angle increments

Two-dimensional projection reconstruction methods provide advantages over three-dimensional techniques because of higher flexibility regarding the resolution and shorter scan time needed. To optimize a two-dimensional radial sequence with respect to signal-to-noise ratio, variable-rate selective excitation and retrospective electrocardiogram gating is investigated. The minimal radiofrequency pulse duration is simulated in dependence of the flip angle and coil parameters using sinc waveforms with two different variable-rate selective excitation approaches and a Fermi pulse. Retrospectively electrocardiogram-gated imaging with Golden Angle incremented projections was implemented to allow for continuous data acquisition enabling the possibility of dynamic electrocardiogram-gated heart imaging. Especially for abdominal coils with high transmitter voltages required, variable-rate selective excitation strongly reduces the radiofrequency pulse duration and echo time resulting in a signal-to-noise ratio gain up to 15.5% (if the fast relaxation component of sodium is in the order of the radiofrequency pulse duration) compared with standard sinc-shaped radiofrequency pulses. Retrospective electrocardiogram gating shows higher flexibility with regard to the trigger delay enabling the trade-off between heart motion artifacts and signal-to-noise ratio. A two-dimensional radial sequence is optimized for sodium heart imaging regarding signal-to-noise ratio. Different sodium contrasts of the human heart are shown, which can give additional information on heart diseases.

Occlusion Devices and Approaches in Canine Patent Ductus Arteriosus: Comparison of Outcomes

A comparison of transvascular occlusion methods for closing patent ductus arteriosus (PDA) in dogs has not been done. To determine if clinically important differences exist between the approaches and devices currently used. A total of 112 client-owned dogs with left-to-right shunting PDA. Retrospective study. Records from dogs that underwent attempted transvascular PDA occlusion from January 2006 to December 2009 were examined. Dogs were placed into 4 groups: Group 1: Amplatz Canine Duct Occluder (ACDO) (transarterial) - 36 dogs; Group 2: Gianturco or MReye Flipper Detachable Embolization (Flipper) coil (transarterial) - 38 dogs; Group 3: Amplatzer Vascular Plug (AVP) (transarterial) - 23 dogs; Group 4: Flipper coil (transvenous) - 15 dogs. The overall success rate of the procedures was high (92%) with comparable success rates among groups (87-97%). There were significantly fewer complications (P < .0001) in dogs receiving an ACDO than in the remaining groups (3% for ACDO versus 26-33% for the other groups). Fluoroscopy time for the transvenous method was significantly longer (median, 13 minutes) than for the other groups (median, 6 minutes) (P < .0001). Severity of residual flow 24 hours postprocedure was significantly less in the ACDO group than in the remaining groups (P = .0001-.05). The ACDO appears superior in ease of use, complication rate, and completeness of occlusion. The remaining limiting factor with this device is patient size. Until a smaller ACDO device is marketed, coils remain the only choice for interventional closure in very small dogs.

Suitability of miniature inductively coupled RF coils as MR‐visible markers for clinical purposes

MR-visible markers have already been used for various purposes such as image registration, motion detection, and device tracking. Inductively coupled RF (ICRF) coils, in particular, provide a high contrast and do not require connecting wires to the scanner, which makes their application highly flexible and safe. This work aims to thoroughly characterize the MR signals of such ICRF markers under various conditions with a special emphasis on fully automatic detection. The small markers consisted of a solenoid coil that was wound around a glass tube containing the MR signal source and tuned to the resonance frequency of a 1.5 T MRI. Marker imaging was performed with a spoiled gradient echo sequence (FLASH) and a balanced steady-state free precession (SSFP) sequence (TrueFISP) in three standard projections. The signal intensities of the markers were recorded for both pulse sequences, three source materials (tap water, distilled water, and contrast agent solution), different flip angles and coil alignments with respect to the B(0) direction as well as for different marker positions in the entire imaging volume (field of view, FOV). Heating of the ICRF coils was measured during 10-min RF expositions to three conventional pulse sequences. Clinical utility of the markers was assessed from their performance in computer-aided detection and in defining double oblique scan planes. For almost the entire FOV (±215 mm) and an estimated 82% of all possible RF coil alignments with respect to B(0), the ICRF markers generated clearly visible MR signals and could be reliably localized over a large range of flip angles, in particular with the TrueFISP sequence (0.3°-4.0°). Generally, TrueFISP provided a higher marker contrast than FLASH. RF exposition caused a moderate heating (≤5 °C) of the ICRF coils only. Small ICRF coils, imaged at low flip angles with a balanced SSFP sequence showed an excellent performance under a variety of experimental conditions and therefore make for a reliable, compact, flexible, and relatively safe marker for clinical use.

Detection of high frequency intensity oscillations at RESEDA using the CASCADE detector

We have explored the technological potential of combining neutron resonance spin echo (NRSE) with the time-of-flight method in quasielastic neutron scattering (QENS) experiments. For these test measurements at the new NRSE instrument RESEDA (FRM II, Munich), we have employed CASCADE, one of the fastest neutron detectors in the world, developed at the University of Heidelberg. Conventionally, scintillation detectors are used, in order to detect neutron intensities with high time resolution. In contrast, we used the new CASCADE detector converting neutrons in thin (10)B layers being capable of resolving neutron intensity modulations up to the megahertz regime. This fast detector allows us to abandon the last resonance flip coil of a standard NRSE setup. The classical spin echo signal is replaced by a time-modulated signal. In this setup, fast intensity modulations are present at the detector position. In order to demonstrate, that NRSE-CASCADE operates well up to detector frequencies of 10 MHz, we performed elastic polarization test measurements on a standard sample. The CASCADE detector is a multidetector accumulating counts in 128 × 128 pixels on a surface of 200 mm × 200 mm. We have analyzed the signal in 600 pixels, providing information about the spin phase reaching the detector and about the resolution function of this new variant tested at RESEDA.

Percutaneous closure of patent ductus arteriosus: A multiinstitutional registry comparing multiple devices

There are no guidelines and multiple devices available now for closure of PDA. We sought to determine which devices are used and their outcomes. Prospectively collected data on closure of PDA at 12 US catheterization labs was entered into the MAGIC data registry between November 2005 and September 2008. PDA closure was accomplished in 357 of 359 attempted closures during the study period. Mean age, weight, and minimum ductal diameter were 4.3 ± 6.8 years, 18.7 ± 18.4 kg, and 2.1 ± 1.4 mm, respectively. Devices used were Gianturco coils (161/359), Amplatzer Duct Occluder (ADO, 174/359), Flipper coils (18/359), and other devices (6/359). Gianturco coils had the least fluoroscopy and contrast exposure (8.7 ± 7.5 min, P = 0.00001, 2.6 ± 1.4 cm(3) kg(-1), P = 0.00001). Immediate angiographic success rates were 96.9% (156/161) for Gianturco coils, 89.7% (156/174) for the ADO, 100% (18/18) for Flipper coils, and 66.7% (4/6) for other devices. Major complication rates were 0.6% for Gianturco coils (1/161), 1.7% for ADO (3/174), and 83.3% for other devices (4/6). Minor complication rates by device were 1.9% for Gianturco coils (3/161), 2.3% for ADO (4/174), and 16.7% (1/6) for other devices. Gianturco coils, the ADO and Flipper coils were immediately successful with low complication profiles. The ADO and Gianturco coils were the predominate devices. The ADO was the device of choice for PDA > 3 mm with good success. In PDA < 3 mm, the Gianturco coil is as effective and safe as the ADO with less cost, less radiation, and less contrast exposure. © 2010 Wiley-Liss, Inc.

Trans‐catheter closure of patent ductus arteriosus—What is the best device?

Over the past three decades, transcatheter occlusion of patent ductus arteriosus (PDA) has evolved to be the procedure of choice. Gianturco and Flipper coils are the most commonly used coils in the United States for closure of small and moderate size PDAs. For larger PDAs, interventionalists in the United States commonly use the Amplatzer Duct Occluder (ADO) and those in Europe use the ADO or the Nit-Occlud Coils (NOC). A comparison between Gianturco coils, Flipper coils, ADO, and NOC has never been made. To compare the success and complication rate associated with the four different devices used for transcatheter closure of PDA. Success was defined as complete closure of PDA with absence of a residual shunt (R.S.) at six months follow-up. Two institutions collaborated in combining their data to evaluate the results of transcatheter closure of PDA. Totally, 546 patients underwent successful PDA occlusion at both institutions. Gianturco and Flipper coils were used in 120 (22%) and 119 (22%) patients respectively. A total of 152 (28%) patients received ADO and 155 (28%) patients received NOC. Immediate R.S. were noted in 226 (41.4%) patients in the entire study group with the NOC group having the highest percentage of R.S. (80/155, 51.6%, P = 0.004). Of the 484 patients with follow-up echocardiograms at 6 months, 35 (7.2%) patients had persistent R.S. The NOC (3/143, 2.1%) and ADO (5/150, 3.3%) groups had the least R.S. at six months follow-up. Per our definition of success, the Nit-Occlud coils and the Amplatzer duct-occluder devices had significantly higher success rate for PDA occlusion versus the coils. © 2010 Wiley-Liss, Inc.

Transcatheter coil occlusion of perimembranous ventricular septal defects

Our purpose was to determine the feasibility and safety of transcatheter coil occlusion of a perimembranous VSD. Transcatheter coil occlusion of a perimembranous ventricular septal defect (VSD) may be a useful treatment; however, there are few reports on its technical aspects and outcome. We attempted coil closure of a perimembranous VSD in 41 patients. We approached the VSD via the right ventricle (RV) in 16, via the left ventricle (LV) in 16, simultaneously deployed two coils from the RV (RV/RV) in three, and simultaneously deployed two, three, or four coils from the RV and LV (RV/LV) in six. Coils (0.038'' flipper, 0.052'' Gianturco, or 0.035'' platinum coil) were placed into the defect through the delivery catheter until any flow through the VSD disappeared or became trivial on angiography. We achieved 100% complete closure in all patients in whom coils were deployed, although some patients required a second session. A flipper coil used alone was insufficient to completely occlude VSDs larger than 2.5 mm. Transcatheter coil occlusion of a VSD can be performed reliably and safely by selecting appropriate embolic coils. Small defects (<2.5 mm) can be closed with a flipper coil, but defects >or=2.5 mm require a 0.052'' coil.

Transcatheter closure of the patent arterial duct using the Flipper coil in a premature infant weighing 1,400 g: A case report

A symptomatic 1,400 g premature triplet underwent successful transcatheter coil embolization of patent arterial duct using the umbilical artery. One 3 mm x 3 cm Flipper coil was used with no angiographic residual shunt. To the best of our knowledge, this is one of the smallest preterm infants to undergo this transcatheter procedure.