Experimental evaluation of a new self-expanding patent ductus arteriosus occluder in a canine model

The investigation of thrombocytopenia after transcatheter occlusion of patent ductus arteriosus

OBJECTIVE

To investigate the risk factors for thrombocytopenia after transcatheter occlusion operation of patent ductus arteriosus (PDA).

METHOD

Retrospective analyses were conducted using clinical data from 106 patients with PDA who underwent transcatheter closure operations at Henan Provincial Chest Hospital, Zhengzhou University, from January 2018 to June 2022. The study compared the changes in platelet counts before and after the operation, and investigated the risk factors for thrombocytopenia following PDA closure in different groups and layers.

RESULTS

The platelet count of patients with PDA significantly decreased after undergoing transcatheter PDA occlusion. Logistic regression analysis revealed that factors such as PDA diameter, occluder diameter, pressure difference on the two sides of the occluder, and residual shunt were associated with an increased risk of thrombocytopenia following PDA occlusion. Specifically, the size of the occluder and the pressure difference between the two sides of the occluder were found to have a negative correlation with the postoperative platelet count. Further subgroup analysis demonstrated that the incidence of total thrombocytopenia was significantly higher in the large PDA group compared to the small-medium PDA groups.

CONCLUSION

Our findings suggest that occluder diameter, the pressure difference between the two sides of the occluder, and the residual shunt are major risk factors correlated with the incidence of postoperative thrombocytopenia. However, a multicenter and long-term prospective study is required to further evaluate the prognosis of PDA patients with thrombocytopenia after transcatheter occlusion.

A fully biodegradable patent ductus arteriosus occlude

The purpose of this study was to develop a fully degradable occluder for the closure of PDA, which can be deployed percutaneously. The blends of biodegradable poly(ε-caprolactone) and poly(L-lactide-co-ε-caprolactone) with various compositions were studied as the potential material. The mechanical properties, i.e. elastic modulus and strain recovery, of the blends could be largely tailored by changing the continuous phase component. Moreover, the suitable blends were selected to fabricate a prototype and its in vitro biodegradation rate and blood compatibility, was evaluated. The current results indicate that no adverse effect on the platelet and leukocyte components of the blood. Biocompatibility implantation studies of the device showed acceptable tissue response. Finally, an artificial PDA conduit was created in a pig, and the device deployment was tested from a sheath: the device recovered within 2-3 min of unsheathing and fully sealed the conduit.

The mechanical behavior and biocompatibility of polymer blends for Patent Ductus Arteriosus (PDA) occlusion device

Patent Ductus Arteriosus (PDA) is a cardiovascular defect that occurs in 1 out of every 2000 births, and if left untreated, may lead to severe cardiovascular problems. Current options for occluding utilize meta scaffolds with polymer fabric, and are permanent. The purpose of this study was to develop a fully degradable occluder for the closure of PDA, that can be deployed percutaneously without open-heart surgery. For percutaneous deployment, both elasticity and sufficient mechanical strength are required of the device components. As this combination of properties is not achievable with currently-available homo- or copolymers, blends of biodegradable poly(ε-caprolactone) (PCL) and poly(L-lactide-co-ε-caprolactone) (PLC) with various compositions were studied as the potential material for the PDA occlusion device. Microstructures of this blend were characterized by differential scanning calorimetry (DSC) and tensile tests. DSC results demonstrated the immiscibility between PCL and its copolymer PLC. Furthermore, the mechanical properties, i.e. elastic modulus and strain recovery, of the blends could be largely tailored by changing the continuous phase component. Based on the thermo-mechanical tests, suitable blends were selected to fabricate a prototype of PDA occluder and its in vitro performance, in term of device recovery (from its sheathed configuration), biodegradation rate and blood compatibility, was evaluated. The current results indicate that the device is able to recover elastically from a sheath within 2-3min for deployment; the device starts to disintegrate within 5-6 months, and the materials have no adverse effects on the platelet and leucocyte components of the blood. Biocompatibility implantation studies of the device showed acceptable tissue response. Finally, an artificial PDA conduit was created in a pig model, and the device deployment was tested from a sheath: the device recovered within 2-3min of unsheathing and fully sealed the conduit, the device remains stable and is completely covered by tissue at 1 month follow up. Thus, a novel prototype for PDA occlusion that is fully degradable has been developed to overcome the limitations of the currently used metal/fabric devices.

Biomaterials and design in occlusion devices for cardiac defects: a review

This review examines the biomaterials used in occlusion devices for cardiac defects, and how the choice of these materials is dictated by design. Specifically, the devices used in three major applications, the atrial septal defect, the ventricular septal defect and the patent ductus arteriosus, are examined critically. A number of different devices are available, with varied performance in deployment and sealing. There is no device in any of the three categories that satisfies fully the range of requirements, and all have associated complications. The type and rate of complications are different among different devices. The short-term (immediate) complications are addressed by immediate retrieval. For longer-term complications, most of which can be fatal, currently only surgical retrieval and replacement are possible. Most of these longer-term complications can be alleviated by the use of fully degradable devices, which will eliminate concerns regarding the use of metals inside the heart, and if fully endothelialized, also minimize migration concerns. On the other hand, the lower moduli of currently available biodegradable materials need to be augmented. Improvements in the stiffness required for deployment can be accomplished with the use of fillers, nano- or micro-sized, and an example of this are radiopaque fillers.

Long-term outcome of transcatheter patent ductus arteriosus closure using Amplatzer duct occluders

BACKGROUND

Immediate-, short-, and intermediate-term results of percutaneous patent ductus arteriosus (PDA) closure using Amplatzer duct occluders are excellent. However, long-term results have not yet been reported to date.

METHODS

Between September 1996 and April 2002, 64 consecutive patients having isolated PDA with minimal diameter of > or =2 mm underwent percutaneous closure using Amplatzer duct occluders. All patients were included in this study and have been followed up until September 2005.

RESULTS

Patients have been followed up from 40 to 108 months (median 58 months). The mean PDA diameter was 3.5 +/- 1.6 mm. There were no deaths or significant complications during the study period. At a 1-month follow-up, all PDA were completely closed and remained closed thereafter.

CONCLUSIONS

Since the initial clinical experience in September 1996, the Amplatzer duct occluder has been proven as a safe and effective device for transcatheter PDA closure. Based on our experience, we believe that in patients having completely closed PDA with laminar blood flow pattern in the descending thoracic aorta and left pulmonary artery at a 1-year follow-up, there is no need for further evaluations. In contrast, few remaining patients need a careful follow-up until a complete normalization of all findings.

Use of a percutaneous atrial septal occluder device for complete acute occlusion of an intrahepatic portosystemic shunt in a dog

A 3-month-old sexually intact male German Shepherd Dog was evaluated because of signs of depression, ataxia, and collapse. Clinicopathologic abnormalities included low serum BUN and albumin concentrations and high serum liver enzyme activities and plasma ammonia and serum bile acids concentrations. Abdominal ultrasonography revealed an intrahepatic portosystemic shunt (PSS). The dog was anesthetized; via a transjugular approach, guidewires and catheters were directed with fluoroscopic guidance to locate the shunt and determine its anatomic features. Minimal changes in portal vein pressure during temporary shunt balloon occlusion enabled complete shunt attenuation, which was performed by use of a self-expanding septal occlusion device that is typically used for treatment of atrial septal defects in humans. Following initial misplacement of the device, the procedure was repeated successfully 2 months later and resulted in complete shunt occlusion. One year after this second procedure, the dog was clinically normal and serum bile acids concentration was within reference limits. In certain dogs with intrahepatic PSSs, treatment with minimally invasive interventional techniques involving fluoroscopy may reduce the morbidity and mortality rates associated with more invasive surgical procedures.

Use of a self-expanding occluding stent for nonsurgical closure of patent ductus arteriosus in dogs

OBJECTIVE

To evaluate the clinical application of a catheter-delivered, self-expanding occluding stent for closure of patent ductus arteriosus (PDA) in dogs.

DESIGN

Prospective study.

ANIMALS

23 client-owned dogs weighing at least 3 kg (6.6 lb).

PROCEDURE

Dogs were evaluated by physical examination, electrocardiography, thoracic radiography, and 2-dimensional, M-mode, spectral and color-flow Doppler echocardiography to confirm the diagnosis and obtain baseline measures. Shunt severity and ductal size and anatomy were established by means of angiography. With fluoroscopic guidance, the occluding stent, attached to a delivery cable, was maneuvered though the right side of the heart into the ductus via a prepositioned introducer sheath. After angiographic verification of appropriate stent placement, the delivery cable was detached, and the introducer sheath was withdrawn. Closure of the PDA was evaluated by means of angiography 15 minutes after stent deployment and by echocardiography 1 and 3 months after the procedure.

RESULTS

There were no operative deaths. There were 2 deployment failures, both attributable to avoidable operator errors. Angiography performed after stent deployment indicated PDA closure in 13 of 20 (65%) dogs. There were 2 postoperative deaths in dogs with heart failure; both deaths were thought to be unrelated to use of the occluding stent. Complete PDA closure, determined by Doppler color-flow echocardiography, was evident in 17 of 19 dogs within 3 months and in 1 additional dog within 1 year of stent deployment, resulting in closure in 18 of 19 dogs completing the study protocol.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that a catheter-delivered occluding stent can be used successfully to close PDAs in dogs.

Transcatheter occlusion of patent ductus arteriosus using a new angled Amplatzer duct occluder: initial clinical experience

In the present study, we report the initial clinical experience with the new angled Amplatzer duct occluder (ADO) for the percutaneous closure of patent ductus arteriosus (PDA). Percutaneous closure of PDA using standard ADO in infants and in patients with small PDA ampulla is difficult, or even impossible, due to protrusion of the aortic disk into the descending thoracic aorta. The aortic disk of an angled ADO is angled at 32 degrees to the body of the device and concave toward the aorta to prevent protrusion of the disk into the aorta. Percutaneous closure of PDA was attempted in nine patients with a median age of 5.2 years (range, 0.5-12.7) and median weight of 20 kg (range, 4.9-55). Selection of the occluder and the implantation technique were similar to the standard ADO. The minimal PDA diameter ranged from 2.1 to 3.7 mm (median, 2.5 mm). Occluders were successfully implanted in all patients. Immediate complete PDA closure was achieved in all patients. There were no complications. The new angled ADO is a safe and effective device for PDA closure, particularly suitable for infants and patients with small PDA ampulla. Further studies and long-term follow-up are necessary to confirm our initial experience.

Closure of large patent ductus arteriosus with a self-expanding duct occluder in two dogs

Of the different catheterisation methods described for closure of patent ductus arteriosus (PDA), coil embolisation is most commonly used in dogs. However, for a PDA larger than 4 to 5 mm in diameter, coil implantation is difficult. For these cases, the Amplatzer duct occluder (ADO) offers an alternative method. This report describes the successful implantation of an ADO in two dogs with large PDAs of approximately 6 mm diameter. The self-expandible device attached to an implantation wire was advanced through a long sheath antegrade to the femoral vein through the right heart and pulmonary artery to the duct and delivered into the PDA. Thereafter the device was released by unscrewing it from the delivery cable. The large PDA in both dogs was totally occluded by these means without any residual shunt. Thus, the ADO is a controlled release implant that also allows occlusion of a large PDA. Its high costs limit its general use in veterinary medicine at the present time.

Transcatheter closure of persistent ductus arteriosus in infants using the Amplatzer duct occluder

AIM

To evaluate whether transcatheter closure with the Amplatzer duct occluder offers an alternative to surgical treatment in infants with a persistent ductus arteriosus.

METHODS

12 patients under 1 year of age (age 1-11 months, body weight 2.6-8.7 kg) with clinical and echocardiographic findings of a significant duct were considered for transcatheter closure with the Amplatzer occluder. The device is made of a Nitinol and polyester fabric mesh and provides occlusion by stenting the duct. Measured angiographically, the narrowest diameter of the ducts ranged from 1.5-5 mm; in six patients pulmonary hypertension was also present.

RESULTS

The devices were implanted and complete duct occlusion was demonstrated during follow up in 10 patients. Procedure related difficulties occurred in nine of the 12 cases and led to relatively long procedure and fluoroscopy times (procedure time 50-180 minutes, median 80 minutes; fluoroscopy time 4.9-49 minutes, median 16 minutes). In two infants transcatheter closure could not be achieved and surgical duct ligation had to be carried out.

CONCLUSIONS

In small infants with a persistent ductus arteriosus the Amplatzer duct occluder offers an alternative to surgical treatment, but further improvement of the implantation system is necessary before the procedure can be recommended as the treatment of choice.

Experimental evaluation of a modified Amplatzer duct occluder

The purpose of this study was to evaluate a new device specifically designed for patent ductus arteriosus (PDA) occlusion based on PDA anatomy. Percutaneous closure of aortopulmonary shunts was attempted in 10 dogs. Shunts were surgically created in the location and orientation of PDA. The occlusion prosthesis consisted of a cylindrical frame filled with polyester and a 32 degree angled retention disk. The delivery system of the device included a 6 Fr thin-walled Teflon introducing sheath, an antirotating delivery catheter, and cable. Complete occlusion of the shunt was obtained in nine animals. One animal died before device placement. Temporary hemolysis occurred in one dog after device placement. The disk of device was completely covered by smooth glistening neoendothelium at 1-3 months postmortem examination. None of the devices protruded into the lumen of the aorta. The device is an improvement over the standard Amplatzer duct occluder. The angled retention disk lies flatly against the aortic wall, avoiding turbulence or an aortic pressure gradient.

Patent ductus arteriosus equipment and technique. Amplatzer duct occluder: intermediate-term follow-up and technical considerations

Between May 1997 and June 2000, 69 patients, ages 0.1 to 34 years, underwent attempted anterograde transcatheter closure of a patent ductus arteriosus (PDA) using the Amplatzer Duct Occluder (ADO). The ADO is a cone-shaped, self-centering, and repositionable occluder made of nitinol wire mesh. A 5Fr to 7Fr sheath was used for the delivery of the device. The mean PDA diameter (at the pulmonary end) was 4.6 +/- 1.9 mm (range 1 mm-8.5 mm). Sixty-seven of the 69 patients had successful device placement. The mean ADO smallest diameter was 6.9 +/- 1.8 mm (range 4 mm-12 mm). Complete angiographic closure occurred in 62 (92.5%) of 67 patients (95% confidence interval, 88.22%-98.77%). In five patients, there was a trivial residual shunt immediately after the procedure. At 24 hours, color Doppler flow imaging revealed complete closure in all 67 (100%) patients. The unsuccessful attempts occurred in two patients with a small, 1-mm diameter native PDA and residual PDA after surgical occlusion. Fluoroscopy time was 7.6 +/- 1.8 minutes (4 min-18 min). No complications were observed. At a median follow-up of 1.5 years (range 0.25 to 3.2 years), all patients had complete closure without complications. We conclude that transcatheter closure using the ADO is a highly effective and safe treatment for most patients with PDA.

Use of a balloon occlusion catheter to facilitate transarterial coil embolisation of a patent ductus arteriosus in two dogs

Two dogs with a history of coughing and exercise intolerance were suspected to have a patent ductus arteriosus (PDA), and the presence of a type III PDA was confirmed by radiography, electrocardiography, ultrasonography and angiography. Transarterial coil embolisation was carried out by using a modified technique. An occlusion balloon catheter was inserted through a femoral vein and placed at the pulmonary side of the ductus before the embolisation coils were put in place. Both dogs remained healthy during a follow-up period of nine months.

Preliminary results with a new vascular basket occluder in swine

PURPOSE

To experimentally evaluate a new self-anchoring vascular occlusion device suitable for use in large, high-flow vessels.

MATERIALS AND METHODS

A basket-shaped occluding device consisting of a nitinol frame (with or without polyester threads) covered with Dacron was evaluated in the common iliac arteries and abdominal aortae of normal pigs. One occluder was placed in each recipient vessel. Angiography was performed before and after placement of each occluder.

RESULTS

Precise placement of the device was achieved in all cases. Mechanically, all but one occluder worked dependably. Angiographically, devices without polyester threads produced only partial occlusion. Devices with threads produced complete occlusion in all but one abdominal aorta, in which partial occlusion occurred because the occluder opened asymmetrically. Complete iliac arterial occlusion occurred within 2-8 minutes of placement and aortic occlusion was achieved within 8-20 minutes. At necropsy, all devices were found to be securely anchored against the vascular wall.

CONCLUSION

Preliminary results indicate that this vascular basket occluder containing polyester threads is easy to place precisely, produces rapid embolization, and demonstrates good self-anchoring ability in a high-flow arterial model.

Transcatheter closure of a large coronary arteriovenous fistula using the new Amplatzer Duct Occluder

A 9-year-old patient with a large coronary arteriovenous fistula (circumflex-right atrium) underwent successful complete percutaneous closure, using the new Amplatzer Duct Occluder (ADO) inserted via a 6 Fr sheath.

Double-helix coil for occlusion of large patent ductus arteriosus: evaluation in a chronic lamb model

OBJECTIVES

We sought to evaluate the efficacy and tissue reaction of a new miniature interventional device for occlusion of large patent ductus arteriosus (PDA) in a neonatal lamb model.

BACKGROUND

A variety of devices are used to close PDAs by interventional measures. Spring coils found to have a high cumulative occlusion rate have thus far been limited to smaller PDAs because of the physical limitation of grip forces.

METHODS

Memory-shaped double-cone stainless steel coils with enhanced stiffness of the outer rings by a double-helix configuration were mounted on a titanium/nickel core wire. A snap-in mechanism attaches the coil to the delivery wire, allowing intravascular coil retrieval and repositioning. The system was placed through a 4F or 5F Teflon catheter. A chronic lamb model (n = 8) of PDA (>5 mm) was used in which ductus patency was secured by a protocol of repetitive angioplasty procedures. The animals were killed after 1 to 181 days, and the ductal region was examined by inspection as well as by light and electron microscopy.

RESULTS

Placement of the coils within the PDA was possible in all lambs. Before final detachment, the coils were retrieved or repositioned, or both, up to 12 times. In all but one animal the ductus was closed within 6 days after the procedure. The coils caused no infections or aortic and pulmonary artery obstruction. Histologic and electron microscopic studies revealed endothelial coverage of the implants but no foreign body reaction or local or systemic inflammation or erosion of the implant.

CONCLUSIONS

The device effectively closed large PDAs in our model and may overcome the previous limitations of coils. Clinical trials are indicated.

Coil on the loop and selectively enhanced stiffness for improved control: feasibility study in the neonatal ovine model of the large patent ductus arteriosus

RATIONALE AND OBJECTIVES

Several devices have been suggested and tested for interventional closure of the persistent ductus arteriosus. Coils were found effective only in small ducts due to their lack of maneuverability and physical limitation of grip forces leading to risk of embolization. The authors evaluated the feasibility to place single coils with selectively enhanced stiffness into high shunting ductus arteriosus, the coils being deployed and controlled through a veno-arterial loop in a bovine model.

METHODS

"Double-cone" shaped, stainless steel coils with enhanced stiffness of the outer rings were mounted on either end on a nitinol core wire. A snap-in mechanism attaches the coil to this delivery wire and is freed by a pusher system of coiled steel wire that is advanced over the core wire. Forming a veno-arterial loop across the patent ductus allows for repositioning into the pulmonary artery or aortic catheter. A chronic lamb model of large patent ductus arteriosus (PDAs) (> or = 9 mm) was used in which ductus patency was secured by a protocol of repetitive angioplasties. Different systems (n = 10) were placed having retrieved the previous coil by a snare after definitive release.

RESULTS

Placement of coils was possible in all 10 attempts. The coils were pulled back into the catheters between five and eight times before definitive release.

CONCLUSIONS

The device allows controlled placement of single coils in our model of large PDAs and may lead the way to overcome previous limitations of coils. Clinical trials are warranted.

Retrievable patent ductus arteriosus plug for interventional, transvenous occlusion of the patent ductus arteriosus. Evaluation in lambs and preliminary clinical results

RATIONALE AND OBJECTIVES

The clinically most widely used devices (Porstmann-plug, Rashkind-umbrella, Botallooccluder) have inherent specific limitations (eg, transarterial approach, residual shunts, limited retrieval). The authors assess practicability, efficacy, and tissue reaction of the new retrievable transvenous plug device for the occlusion of the persistent patent ductus arteriosus (PDA).

METHODS

A foam plug (polyvinyl alcohol) is mounted on a titanium core pin where, at both ends, small legs (titanium nickel alloy) with titanium heads are anchored, to ensure safe fixation in the ductus. The device is introduced transvenously through a long sheath (Mullins sheath) and held by a modified biopsy forceps allowing complete retrieval until final release. A common lamb model of large PDAs (n = 11) was used to test for practicability and the histomorphologic outcome. Clinical results were obtained from a consecutive series of 16 patients (aged 13 to 71 years).

RESULTS

In all lambs, placement of the plug within the PDA was possible. Histopathology (follow-up 10 to 215 days; mean 112 days) revealed an adequate ingrowing of the device and no pathologic foreign body reaction. The diameter of the human PDAs ranged from 3 to 7 mm (mean 5 mm). The size of the sheath used for introducing the plug (diameter 8 to 16 mm) ranged from 8 to 16 French. Fourteen of 16 PDAs were closed immediately after or on day 1 after implantation, 1 was closed after the 12-month follow-up, and 1 needed an additional plug after 30 months for definitive closure.

CONCLUSIONS

The device demonstrated practicability and biocompatibility in our experimental lamb model and effectively closed the PDA in a consecutive series of 16 patients. A greater number of patients and a longer follow-up period are necessary for the definitive clinical assessment of the new device.