Coil Implantation Research Articles

High Retention and Safety of Percutaneously Implanted Endovascular Embolization Coils as Fiducial Markers for Image-guided Stereotactic Ablative Radiotherapy of Pulmonary Tumors

High Retention and Safety of Percutaneously Implanted Endovascular Embolization Coils as Fiducial Markers for Image-guided Stereotactic Ablative Radiotherapy of Pulmonary Tumors

High Retention and Safety of Percutaneously Implanted Endovascular Embolization Coils as Fiducial Markers for Image-Guided Stereotactic Ablative Radiotherapy of Pulmonary Tumors

To compare the retention rates of two types of implanted fiducial markers for stereotactic ablative radiotherapy (SABR) of pulmonary tumors, smooth cylindrical gold "seed" markers ("seeds") and platinum endovascular embolization coils ("coils"), and to compare the complication rates associated with the respective implantation procedures. We retrospectively analyzed the retention of percutaneously implanted markers in 54 consecutive patients between January 2004 and June 2009. A total of 270 markers (129 seeds, 141 coils) were implanted in or around 60 pulmonary tumors over 59 procedures. Markers were implanted using a percutaneous approach under computed tomography (CT) guidance. Postimplantation and follow-up imaging studies were analyzed to score marker retention relative to the number of markers implanted. Markers remaining near the tumor were scored as retained. Markers in a distant location (e.g., pleural space) were scored as lost. CT imaging artifacts near markers were quantified on radiation therapy planning scans. Immediately after implantation, 140 of 141 coils (99.3%) were retained, compared to 110 of 129 seeds (85.3%); the difference was highly significant (p<0.0001). Of the total number of lost markers, 45% were reported lost during implantation, but 55% were lost immediately afterwards. No additional markers were lost on longer-term follow-up. Implanted lesions were peripherally located for both seeds (mean distance, 0.33 cm from pleural surface) and coils (0.34 cm) (p=0.96). Incidences of all pneumothorax (including asymptomatic) and pneumothorax requiring chest tube placement were lower in implantation of coils (23% and 3%, respectively) vs. seeds (54% and 29%, respectively; p=0.02 and 0.01). The degree of CT artifact was similar between marker types. Retention of CT-guided percutaneously implanted coils is significantly better than that of seed markers. Furthermore, implanting coils is at least as safe as implanting seeds. Using coils should permit implantation of fewer markers and require fewer repeat implantation procedures owing to lost markers.

Achieving low defibrillation thresholds at implant: pharmacological influences, RV coil polarity and position, SVC coil usage and positioning, pulse width settings, and the azygous vein

Approximately 30% of implantable cardioverter defibrillator (ICD) patients still die of sudden death. A major cause of these sudden deaths is the failure to defibrillate because of failure to achieve a low defibrillation threshold (DFT). Anti-arrhythmic drugs can have a profound positive or negative effect on the DFT. Unfortunately, present clinical practice continues to feature many procedures and tactics that have minimal to negative DFT benefit. In addition, many demonstrated helpful tactics are not understood or followed. This review covers the optimal RV (right ventricular) coil position and polarity, superior vena cava (SVC) coil positioning and usage, pulse width settings, and azygous vein coil implants. Specifically, the RV coil should be set to an anodal polarity and never 'reversed'. The optimal RV coil position appears to be along the mid-septum. The SVC coil should be kept out of the right atrium and placed in the innominate vein junction. The SVC coil should be always on for high impedance patients. For low impedance patients, the SVC coil should be set on or off depending on which setting gives the lowest DFT. Pulse widths should be set to correspond to optimally charging and discharging a cardiac membrane time constant of between 3.5 and 4.5 ms. For the highest DFT patients, a separate coil should be placed in the azygous vein and connected to the ICD 'SVC' port. Anachronistic approaches such as the use of polarity reversal, apical RV coil tip forcing, and subcutaneous arrays are also discussed.

Percutaneous Epicardial Defibrillation Coil Implantation

Received December 8, 2009; revision accepted February 9, 2010. A 70-year-old African American female with known history of nonischemic cardiomyopathy (ejection fraction, 15%) was referred for BiVentricular implantable cardioverter-defibrillator (BiV-ICD) implantation for primary prevention. Because of a previous left mastectomy for breast cancer and occlusion of the left subclavian axillary venous system, a right-sided prepectoral implant was chosen for this patient. The procedure included a right-sided prepectoral BiV-ICD implantation, implantation of a right atrial appendage active fixation lead, a single-coil active fixation right ventricular lead, and a left ventricular coronary sinus lead. During the routine testing of the ICD, the defibrillation threshold (DFT) was >35 J, requiring external cardioversion. A second DFT testing performed thereafter with a polarity modification was also >35 J. The patient was subsequently treated with sotalol 80 mg bid for 1 week and the DFT was repeated but was still refractory (>35 J). Hence, alternate options were entertained. Although a left-sided subcutaneous coil array was considered, it was abandoned because the coil extension had to cross the midline of the chest. However, a percutaneous epicardial defibrillation coil implantation was considered (Figure 1A). Figure 1. A, Anteroposterior chest radiograph showing the BiV-ICD generator in the right prepectoral region with the defibrillation coil (halo) in the pericardial space. B, Subxyphoid approach (arrow) to access the pericardial space. Note …

Immediate Echocardiographic Surveillance After Transcatheter Closure of a Patent Ductus Arteriosus: A Feasible Method to Assess Residual Shunt

To evaluate the feasibility of echocardiography after transcatheter closure of patent ductus arteriosus (PDA) with coils. Between April 1998 and December 2006, 131 patients had transcatheter coil occlusion of their PDA using Gianturco coils. We hypothesized that post-procedural hemolysis would not occur if a residual shunt < 1 mm or if no continuous waveform was detected by echocardiography. Immediately after coil implantation, patients without and with a residual shunt as detected by echocardiography were designated to groups A and B, respectively. The clinical presentations, laboratory data and outcomes were compared between the two groups. There were 101 patients in group A and 30 patients in group B. Patients in group B had larger ductal diameter (2.8 +/- 0.9 mm vs. 1.6 +/- 0.8 mm; p < 0.001), larger Qp/Qs (1.9 +/- 0 .9 vs. 1.3 +/- 0.4; p = 0.001), higher frequency of more than one coil used (14/30 vs. 11/101; p < 0.001), and female predominance (22/30 vs. 53/101; p = 0.043) compared with group A. Trivial residual shunt was noted in 6 patients in group A and 20 patients in group B on the day after embolization. All shunts spontaneously closed within 6 months in patients of group A, while five patients in group B had a persistent shunt at the 1-year follow-up and thereafter. Although the patients in group B had higher residual shunt rate than group A during follow-up (p < 0.001), none of these patients suffered from hemolysis. Echocardiography is a feasible tool to assess residual shunt after PDA closure. If a residual shunt < 1 mm or if no continuous waveform is detected by echocardiography, the risk of developing hemolysis is low.

Risk evaluation and interventional planning for cerebral aneurysms: computational models for growth, coiling and thrombosis

The clinical treatment of cerebral aneurysms, from detection to post-intervention follow-up care, poses a series of challenges, both clinical and technical. The introduction of computational simulation techniques, in all stages of the procedure, allows for, or promises to provide, patient-specific risk evaluation, rationalisation and optimisation of surgical or interventional planning and a priori evaluation of treatment efficacy and long-term outcome. In this article, we present techniques that allow for the simulation of growth of cerebral aneurysms, based on detailed vascular wall remodelling techniques. Moreover, we demonstrate that computational techniques allow the pre-interventional evaluation of the effectiveness of detachable coil implantation. Finally, appropriate coupling of the haemodynamics of flow with thrombosis models allows for the prediction of the growth of clot; of great importance both of the eventual healing of the lesion in case of endovascular coil treatment for cerebral aneurysms but also as an indicator of the spontaneous formation of microembolic clots.

Scoliosis in Patients with Aortic Coarctation and Patent Ductus Arteriosus: Does Standard Posterolateral Thoracotomy Play a Role in the Development of the Lateral Curve of the Spine?

The aim of this study was to determine the influence of lateral thoracotomy on the development of scoliosis in subjects undergoing repair of coarctation of the aorta (CoA) and patent ductus arteriosus (PDA). A group of 133 patients with CoA and PDA was evaluated. Forty-five patients with CoA and 38 with PDA underwent surgery using standard posterolateral thoracotomy (operative group), whereas 12 patients with CoA and 31 with PDA were treated using balloon dilatation and stent or coil implantation (nonoperative group). A spinal examination, together with the evaluation of chest and spinal roentgenograms, was conducted. Among the operated patients, 62% of those with CoA and 55% of those with PDA had clinical scoliosis. In the nonoperated patients, scoliosis was present in only 25% of those with CoA and 16% of those with PDA. Scoliosis ranged between 10 degrees and 42 degrees . In 89% of the operated patients with CoA and 76% of those with PDA the curve was thoracic; in 46% of the CoA group and 57% of the PDA group the curve was left-sided. All curves were right-sided in nonoperated subjects. Scoliosis in the operated group was higher in male than in female subjects (63% vs. 60% in CoA and 86% vs. 37% in PDA). The prevalence of scoliosis after standard posterolateral thoracotomy was significantly higher than after nonsurgical treatment methods in the CoA and PDA groups as well as in the general population. The rate of single thoracic and the rate of left-sided thoracic curves in patients after thoracotomy is higher than in nonoperated patients or in those with idiopathic scoliosis. The rate of scoliosis after thoracotomy is higher in male than female patients, especially after thoracotomy for PDA.

Comparison of two transcatheter device strategies for occlusion of the patent ductus arteriosus

The present study evaluates two transcatheter closure strategies utilized at a single center and makes recommendations for device selection when occluding the patent ductus arteriosus. A variety of devices are available for transcatheter closure of the patent ductus arteriosus (PDA) but no guidelines exist to guide operator device choice. A total of 132 patients underwent attempted transcatheter PDA closure utilizing one of two consecutive closure strategies between January 2000 and June 2005. Strategy A (n = 64; January 2000-May 2003) utilized Gianturco coils only. Strategy B (n = 68; June 2003-June 2005) utilized a single Gianturco coil for the PDA with a minimal diameter <or=1 mm (n = 28) or an Amplatzer Duct Occluder (ADO) if the PDA diameter exceeded 1 mm (n = 40). Success was defined as complete occlusion on a follow up echocardiogram. 58 of 64 (90.6%) patients treated utilizing strategy A had successful coil implantation. 68 of 68 (100%) patients treated utilizing strategy B had successful coil/device implantation. At follow up echocardiography, 32 of 44 (72.7%) strategy A patients had complete ductal closure, as compared with 57 of 58 (98.3%) strategy B patients (P < 0.0001). Stepwise logistic regression analysis identified closure strategy as the most powerful predictor of procedural success (OR = 85.9; CI 5.6-9.99). A transcatheter PDA closure strategy consisting of a single Gianturco coil for PDA <or= 1 mm or an ADO for larger sized PDA (strategy B) achieves superior outcomes compared to the use of coils alone.

Towards a microcoil for intracranial and intraductal MR microscopy.

Implantable RF-coils have enabled sub-mm resolution magnetic resonance images (MRI) of deep structures. Scaling down the size of RF coils has similarly provided a gain in signal-to-noise ratio in nuclear-magnetic-resonance spectroscopy. By combining both approaches we designed, fabricated, and imaged with an implantable microcoil catheter. While typical implantable catheters use a transverse magnetization, the axial magnetization of the microcoil provides improved sensitivity and allows visualization of the tissue beyond the distal end of the catheter. The microcoil catheter was designed with a diameter of 1 mm for future integration with intracranial devices, and for intraductal use in breast oncology. We modified the NMR-microcoil design to allow implantation of the RF coil, by winding the microcoil on medical-grade silicone tubing and incorporating leads on the catheter to connect circuit components. In order to achieve proper turn spacing, we coated copper wire with 25 microm of biocompatible polymer (Parylene C). Tuning and matching circuitry insured that the impedance of the RF coil was approximately 50 ohm at the operating frequency for 3-T proton MR applications. A duplexer was used to enable use of the microcoil catheter as a transceiver. Experimental verification of the coil design was achieved through ex vivo imaging of neural tissue. As expected, the microcoil catheter provided microscale images with 20-microm in-plane-resolution and 170-microm-thick slices. While 3-T MRI typically provides 1 to 30 voxels per-cubic-millimeter, in this paper we report that the MRI microcoil can provide hundreds, and even thousands of voxels in the same volume.

Percutaneous closure of previously surgical treated arterial ducts

To report our experience and strategies with transcatheter closure of residual patent ductus arteriousus (RPDA) in patients with previous surgical ligation. Transcatheter closure of residual patent ductus arteriousus after surgical ligation was attempted in 19 patients. In 13 patients the residual patent ductus arteriosus was closed with detachable coils, in four with Rashkind umbrella and in two with Amplatzer occluder. In order to cross the recanalised duct with the delivery system a vascular loop was required in six patients. Complete closure of residual ducts were achieved in all but one patient. Transcatheter closure appears to be a safe and effective treatment for residual persistent duct. Coil implantation seems to be the best option in the case of smaller ducts, and in larger ones the Amplatzer Duct Occluder appears to be superior. Taking a meticulous approach to choosing the correct device should prevent ineffective treatment.

The Amplatzer Vascular Plug Also for Ovarian Vein Embolization

We read with interest the paper by Tuite and colleagues [1] regarding their retrospective review of 23 consecutive cases of vascular embolization using the Amplatzer Vascular Plug (AVP), a new self-expanding nitinol wire mesh vascular embolization device delivered and released only when satisfactorily positioned. The AVP is commonly used in place of coils. The most frequent complication of coil embolization is coil migration if there were some problem in choosing the right size; other less common complications include erosion of the structures in which the coils are located, or infection [2, 3]. The standard treatment for female pelvic congestion syndrome is foam sclerotherapy into the ovarian vein below the level of the pelvic brim followed by coil embolization to within a centimeter of the vein origin [4, 5]. Commonly, due the fact that the ovarian veins are large, multiple coils are needed to complete the procedure, increasing the potential rate of the above-mentioned complications and the radiation exposure in young women. We treated a 39-year-old woman with pelvic congestion syndrome using sclerotherapy plus proximal ovarian vein embolization with AVPs (Fig. 1). We found delivery of the system to be very safe and quick. We needed only two AVPs (12 and 14 mm) (Fig. 1) and the patient is symptomfree after 9 months of follow-up. Even though larger series and longer follow-ups are needed we think that AVP embolization could be used also in ovarian vein embolization, partially obviating the limitations and complications of coil implantation and also reducing the radiation exposure in young women. To the best of our knowledge this is the first reported case of ovarian AVP embolization.

Inadvertent stenting of patent ductus arteriosus with Amplatzer Vascular Plug

We report a 12-month old patient who presented for murmur evaluation after percutaneous closure of type C patent ductus arteriosus (PDA) using a 10 mm Amplatzer Vascular Plug (AGA Medical Corporation, Golden Valley, MN) at an outside institution. Echocardiography revealed a large left-to-right shunt through the implanted device, inadvertently stenting the PDA instead of closing it. The patient underwent repeat catheterization with successful coil implantation within the Amplatzer Vascular Plug, completely eliminating the large residual ductal shunt. Although challenging, this case illustrates the technique of implanting coils within this occlusion device. This case also illustrates that occlusion of type C PDA utilizing the Amplatzer Vascular Plug may not only result in incomplete occlusion but also create a potentially worse clinical situation in which the PDA is stretched larger and stented open. Without consideration of simultaneous coil implantation within this device, use of the Amplatzer Vascular Plug might be contraindicated in type C PDA, because there may be no way to ensure successful closure by the Vascular Plug alone.

Immediate and Late Outcomes of Transarterial Coil Occlusion of Patent Ductus Arteriosus in Dogs

Records from dogs (n = 125) that underwent attempted transarterial coil occlusion of patent ductus arteriosus (PDA) at the University of California, Davis, between 1998 and 2003, were reviewed, and a subset of these dogs (n = 31) in which the procedure was performed at least 12 months earlier were reexamined to determine long-term outcome. Coil implantation was achieved in 108 dogs (86%). Despite immediate complete ductal closure in only 34% of dogs, the procedure was hemodynamically successful as evidenced by a reduction in indexed left ventricular internal diameter in diastole (LVIDd; P < .0001), fractional shortening (P < .0001), and left atrial to aortic ratio (LA: Ao; P = .022) within 24 hours. Complete ductal closure was documented in 61% of dogs examined 12 to 63 months after coil occlusion. Long-standing residual ductal flow in the other 39% of dogs was not associated with increased indexed LVIDd or LA: Ao and was not hemodynamically relevant. Repeat intervention was deemed advisable in only 4 dogs with persistent (n = 1) or recurrent (n = 3) ductal flow. Complications included aberrant embolization (n = 27), death (n = 3), ductal reopening (n = 3), transient hemoglobinuria (n = 2), hemorrhage (n = 1), aberrant coil placement (n = 1), pulmonary hypertension (n = 1), and skin abscessation (n = 1). Serious infectious complications did not occur despite antibiotic administration to only 40% of these dogs. Transarterial coil occlusion was not possible in 14 dogs (11%) because of coil instability in the PDA and was associated with increased indexed minimum ductal diameter (P = .03), LVIDd (P = .0002), LVIDs (P = 0.001), and congestive left heart failure (P = .03) reflecting a relatively large shunt volume.

Immediate and Late Outcomes of Transarterial Coil Occlusion of Patent Ductus Arteriosus in Dogs

Records from dogs (n = 125) that underwent attempted transarterial coil occlusion of patent ductus arteriosus (PDA) at the University of California, Davis, between 1998 and 2003, were reviewed, and a subset of these dogs (n = 31) in which the procedure was performed at least 12 months earlier were reexamined to determine long‐term outcome. Coil implantation was achieved in 108 dogs (86%). Despite immediate complete ductal closure in only 34% of dogs, the procedure was hemodynamically successful as evidenced by a reduction in indexed left ventricular internal diameter in diastole (LVIDd; P &lt; .0001), fractional shortening (P &lt; .0001), and left atrial to aortic ratio (LA: Ao; P = .022) within 24 hours. Complete ductal closure was documented in 61% of dogs examined 12 to 63 months after coil occlusion. Long‐standing residual ductal flow in the other 39% of dogs was not associated with increased indexed LVIDd or LA: Ao and was not hemodynamically relevant. Repeat intervention was deemed advisable in only 4 dogs with persistent (n = 1) or recurrent (n = 3) ductal flow. Complications included aberrant embolization (n = 27), death (n = 3), ductal reopening (n = 3), transient hemoglobinuria (n = 2), hemorrhage (n = 1), aberrant coil placement (n = 1), pulmonary hypertension (n = 1), and skin abscessation (n = 1). Serious infectious complications did not occur despite antibiotic administration to only 40% of these dogs. Transarterial coil occlusion was not possible in 14 dogs (11%) because of coil instability in the PDA and was associated with increased indexed minimum ductal diameter (P= .03), LVIDd (P= .0002), LVIDs (P= 0.001), and congestive left heart failure (P= .03) reflecting a relatively large shunt volume.

Mechanical and radiographic properties of a shape memory polymer composite for intracranial aneurysm coils

An intracranial aneurysm can be a serious condition that can go undetected until the aneurysm ruptures, causing hemorrhaging within the subarachnoid space surrounding the brain. The typical treatment for large aneurysms is by embolization using platinum coils. However, in about 15% of the cases treated by platinum coils, the aneurysm eventually re-opens as a result of the bio-inertness of platinum. One solution to this is to develop suitable materials with increased bio-activity to use as coil implants. In this research, a shape memory polymer (SMP), Calomer™, produced by The Polymer Technology Group, Inc., was investigated as a candidate for aneurysm coils. The SMP was tested to determine its thermo-mechanical properties and the strength of the shape recovery force. Composite SMP specimens containing tantalum filler were produced and tested to determine the mechanical effect of adding this radio-opaque metal. Thermo-mechanical testing showed that the material exhibited a shape recovery force a few degrees above the glass transition temperature, T g. The effects of the addition were small and included a decrease in T g and recovery force. SMP coils deployed inside a simulated aneurysm model demonstrate that typical hemodynamic forces do not hinder the shape recovery process. The radio-opacity of the Ta-filled material was characterized with clinical fluoroscopy.

Treatment of Experimentally Induced Aneurysms with Stents

Although Guglielmi detachable coil systems have been widely accepted for treatment of intracranial aneurysms, primary stenting of aneurysms using porous stents, stent grafts, or implantation of coils after stent placement constitute emerging techniques in endovascular treatment. The aim of the present study was to use an animal model to investigate these different approaches to treat cerebral aneurysms with regard to the rate of closure and the histopathological changes within the aneurysm cavity and the parent vessel after stent placement. We created aneurysms in 30 rabbits by distal ligation and intraluminal incubation of the right common carotid artery with elastase. Ten animals were treated with porous stents alone, 10 animals with stent grafts (covered stents), and 10 animals with stents and additional coiling via the interstices of the stent, which enabled dense packing of the coils. Five animals in each group were observed for 1 month and the other animals for 3 months. Histological analyses were performed, including immunohistochemical investigations for estimating the proliferation of the intima and possible inflammatory infiltration. Covered stents led to a complete and stable aneurysm occlusion with only minimal proliferative carrier vessel wall changes. One covered stent was completely occluded with old thrombus, and the other 9 remained patent. Porous stents occluded two of five aneurysms in the 1-month follow-up group and four of five after 3 months. However, progressive sprouting of neointima inside the carrier vessel that resulted in a stenosis of up to 40% was present. In the Stent + Coil group, one aneurysm showed recanalization after 1 month, and three of five aneurysms were recanalized after 3 months after coil compaction. Moreover, in-stent stenosis of up to 30% was present. This study demonstrates the possible shortcomings and problems of emerging stent techniques to treat intracerebral aneurysms, shows where technical advances have to be made, and describes in which cases of aneurysm morphology caution has to be exercised when considering an endovascular approach using stents.

Challenges Encountered During Closure of Patent Ductus Arteriosus

Transcatheter closure of patent ductus arteriosus (PDA) was one of the first interventions established in invasive cardiology and is now more than 30 years old. The challenges for successful closure with the first devices in children consisted of handling the rather large introducer sheaths and stiff application systems. Today, interventional closure can be performed with different types of plugs, occluders, and coils. Thus, beyond infancy, transcatheter closure can be successfully performed in almost all cases. Challenging from the technical standpoint can be the closure of window-type ducts, in which excessive protrusion of the device into the descending aorta should be avoided, as well as the closure of tubular ducts, in which secure anchoring of one or more devices in the vessel can be very difficult. For the combination of a coarctation and an open duct, different strategies can be considered. In selected cases, use of a covered stent can be helpful. From the physiological standpoint, open ducts in patients with pulmonary hypertension with or without concomitant congenital heart diseases can be challenging because testing of vasoreactivity with temporarily blocked duct and the option of subsequent treatment with vasodilators may be necessary prior to making the decision whether the patient may benefit from definitive duct occlusion or not. Large ducts in infants less than 8 kg can be difficult to treat due to a relative mismatch of introducers, plugs, or occluders to the small anatomic dimensions. The implantation of multiple coils can be associated with a higher risk of device embolization. Unfortunately, for the large group of preterm infants with very low body weights and large ducts of tubular shape there is currently no standardized interventional therapy available.

Percutaneous transcatheter coil embolization of a ventricular septal defect in a dog

A 4-month-old male French Bulldog weighing 5.0 kg (11 lb) was referred for a heart murmur. A grade 3/6 systolic murmur was detected at the left heart base and a grade 4/6 systolic murmur was detected at the right heart base. By use of color-flow Doppler ultrasonography and cardiac catheterization, a diagnosis of supracristal ventricular septal defect (VSD) with accompanying aortic regurgitation was made. Percutaneous transcatheter coil embolization was used to close the VSD. Because residual shunt was detected via echocardiography after coil implantation, the residual shunt was followed periodically via echocardiography to detect spontaneous closure of the VSD. Volume overload in the left ventricle was detected in the dog 131 days after admission. Additional coils were placed 137 days after admission. Hemolysis resulting in hemoglobinuria was detected, but this complication was mild. In the dog of this report, results of coil occlusion for correction of VSD were promising. Thus, coil occlusion should be considered as an alternative treatment for VSD in dogs.

A Technique for the Measurement of Renal ATP in a Large Animal Model of Septic Shock

The mechanisms responsible for acute renal failure in sepsis are not understood. Measurement of tissue ATP might help to understand this process but, in the large animal, it is hampered by major technical difficulties. To develop a technique to monitor ATP in the kidney of a large mammal during the induction of septic shock and then circulatory arrest. Implantation of a custom-made phosphorus coil around the left kidney. Induction of septic shock by intravenous E. coli administration. Acquisition of 31 P magnetic resonance (MR) spectroscopic data at 3-tesla before and during septic shock over several hours. Induction of euthanasia and measurement of the same 31 P signal immediately and thirty minutes after circulatory arrest. Clear reproducible 31 P MR spectra were obtained before and after the induction of septic shock and euthanasia. They indicated limited changes in ATP during septic shock. An expected rapid and dramatic decrease in ATP occurred with euthanasia. It is possible to sequentially monitor renal bioenergetics in a large mammal during septic shock using an implanted custom-made phosphorus coil and 3-tesla MR technology. This technique offers a novel approach to the investigation of septic renal failure.

Transcatheter closure of patent ductus arteriosus with Nit-Occlud coils

The detachable coils have been successfully used for transcatheter occlusion of small- to moderate-sized patent ductus arteriosus (PDA). We report our experience regarding the use of the Nit-Occlud coils (NOCs) for transcatheter PDA and major aortopulmonary collateral (MAPCA) occlusion. Single NOCs were used to close PDA in 26 patients, and one small and two large MAPCAs in two patients. Mean age and weight of the patients were 7.7 +/- 5.4 years and 20.6 +/- 11.6 kg. Mean minimum duct diameter was 2.8 +/- 0.8 mm; ampulla, 8.7 +/- 2.4 mm; and PDA length, 9.3 +/- 4.4 mm. Mean pulmonary artery pressure ranged from 9 to 51 mm Hg and pulmonary/systemic flow ratio from 1.1 to 5.8. Ductal shape was conical in 24 patients. Route of approach was venous in 23 and arterial in 3. Successful coil implantation was achieved in 24/26 (92.3%). Mean procedure and fluoroscopy time were 67.2 +/- 22.1 and 14.9 +/- 6.5 min. The three MAPCAs were also successfully occluded using NOC Medium and Flex. Postimplantation angiograms revealed no leak in 3, a trace or small leak in 17, and a medium leak in 4 patients. Mean follow-up was 7 +/- 5 months. Complete occlusion was achieved in 17/24 (71%) at 24 hr, 19/24 (79%) by 1 month, 13/15 (87%) by 3 months, 14/15 (93%) by 6 months, and 10/11 (90%) by 12 months postprocedure. Hemolysis, late embolization, duct recanalization, and flow disturbances were not observed. Transcatheter occlusion of moderate-sized PDAs and MAPCAs using NOCs seems to offer a safe, simple, and controlled method in pediatric patients.