A new device for transcatheter closure of the patent ductus arteriosus. A feasibility study in dogs

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.

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.

Enhanced occlusion of vessels combining retrievable, detachable coils as differential electrodes with percutaneous, intravascular radiofrequency electrocoagulation. An experimental study

RATIONALE AND OBJECTIVES

The authors evaluate the feasibility to accelerate occlusion of high-velocity flow vessels by a combination of transcutaneous coil placement and application of radiofrequency current.

METHODS

Piglets (n = 8) were anesthetized and acutely instrumented via cutdowns in both carotid and one brachial arteries. Two identical cylindrically shaped coils (length, 3 mm; outer diameter, 2.4 mm; inner diameter, 1.4 mm) were mounted on titanium-nickel core wire and placed via 3-French Nylon catheters in both iliac arteries. The coils were kept connected to the delivery wire, which is isolated from the surrounding tissue by the catheter. The first-placed system served as control, the contralateral coil was connected to a radiofrequency generator closing electrical circuit via an external indifferent electrode. Angiograms via the brachial artery demonstrated the adequate placement of the coils and the status of the iliac arteries without and with current application. In 6 of the 8 cases, 25 watts of radiofrequency current were applied repeatedly over 10 seconds to the coil on one side at 4-minute intervals until occlusion was demonstrated. In 2 of 8 cases. 25 watts were applied continuously over 30 seconds. The coils were detached from the wire the catheters removed. Additional angiograms were performed after 5, 15, 45, and 60 minutes to show the patency of the control setting.

RESULTS

Complete occlusion was achieved in all cases after a maximum of three consecutive applications of current for 10 seconds. The control remained patent for a minimum of 45 minutes. On gross and histologic examination the arteries on both sides remained intact. Disruption and charring occurred only after continuous application of current over 30 seconds.

CONCLUSIONS

It is feasible to use detachable coils in conjunction with high-frequency electrocoagulation to promote coil fixation and accelerate occlusion of vessels with high blood flow.

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

PURPOSE

A new self-expanding patent ductus arteriosus (PDA) occluder was designed.

MATERIALS AND METHODS

Percutaneous closure of surgically created aortopulmonary shunts was attempted in 19 dogs. The occlusion device consisted of a nitinol wire frame tightly woven into a cylinder with a flat retention disc. A polyester-filled frame was used in the last six procedures. A 6-F introducing sheath was advanced across the aortopulmonary conduit into the descending thoracic aorta. The prosthesis (attached on a stiff delivery cable) was advanced through the introducing sheath. The retention disc was first released in the descending thoracic aorta, then the cylindrical device frame was expanded within the conduit by withdrawing the sheath.

RESULTS

Subtotal misplacement into the descending aorta occurred in one procedure (overall technical success rate, 95%), and one animal died before the 1-week follow-up. Complete angiographic shunt closure was achieved in seven of 18 (39%) animals at 30 minutes, 12 of 17 (71%) animals at 1 week, 14 of 17 (82%) animals at 1 month, and 11 of 12 (92%) animals at 3 months. Significantly higher 30-minute closure rates occurred with polyester-filled occluders compared with nonfilled occluders (five of five [100%] vs one of 13 [15%]; P = .002). Persistent shunt at 3 months occurred in only one nonfilled device (6%). In the remaining 16 animals, both orifices of the shunt were covered by a smooth glistening neoendothelium at postmortem examination.

CONCLUSION

This device combines the advantages of small delivery system, easy placement, self-centering, and repositionability. Immediate shunt closure can be reliably accomplished with the polyester-filled prosthesis.

Transcatheter occlusion of patent ductus arteriosus: which method to use and which ductus to close

Many devices have been developed for transcatheter occlusion of PDA. Bulkiness of the device, complexity of the procedure, and significant residual complications make the majority of the devices unsuitable for routine clinical use. Although no randomized comparative clinical trials exist, on the basis of published literature and my personal experience, coil occlusion may be best suited to close small ducts (< or = 3.5 mm) and the adjustable buttoned device may be most appropriate for large PDAs (> 3.5 mm). Clinical trials on larger patient populations than are currently available and long-term follow-up are necessary to further support these recommendations. Indications for transcatheter closure should be exactly as those used for surgical closure: PDA with audible continuous murmur with echo Doppler confirmation. The so-called silent ducts need not be closed.

A small interventional device to occlude persistently patent ductus arteriosus in neonates: evaluation in piglets

OBJECTIVES

We attempted to evaluate the efficacy and tissue reaction of a new miniature interventional ductal occlusion device in neonatal pigs.

BACKGROUND

A variety of devices are used to close persistent ductus arteriosus (PDA) by interventional measures. Because of the size of these devices, they have not been applied to term or preterm neonates. Newborn piglets are comparable in size and fragility to human term and preterm neonates.

METHODS

Memory-shaped double-cone stainless steel coils 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 3F Teflon catheter. Two piglet models of PDA were used: 1) ductal patency maintained by stents (n = 6), and 2) ductal patency produced by angioplasty (n = 7) to avoid stent-coil interaction.

RESULTS

Placement of the coils within the PDA was possible in all piglets. Before final detachment, the coils were retrieved or repositioned, or both, up to eight times. In all but two piglets the ductus was closed within 1 h of the procedure. The coils were never dislocated and caused no infections or relevant aortic and pulmonary artery obstruction (95% confidence interval for missing complications [0 of 13] extends to 23%). Histologic and electron microscopic studies revealed endothelial coverage of the implants and histiocytic reaction but no local or systemic inflammation or erosion of the implant.

CONCLUSIONS

The device was effective in experimental models of PDA. The information obtained warrants initial trials of the device in neonates.

Repositionable vascular occluder: experimental comparison with standard Gianturco coils

PURPOSE

To evaluate the efficacy and recanalization rates of a newly designed vascular occlusion device.

MATERIALS AND METHODS

The self-expanding vascular occluder was braided from fine nitinol wires and filled with polyester fibers. The device was delivered through a 6-F polyethylene introducing sheath with use of a delivery cable with a microscrew adaptor. Comparison was made between one occlusion plug and two Gianturco coils placed in the corresponding contralateral arterial segment in nine dogs and six pigs. The mean diameter of the targeted vessels was 4.8 mm +/- 0.8. Two animals were killed immediately after occlusion, and the remaining 13 animals underwent follow-up angiography at 1 week and/or 1 month, after which the animals were killed and the vessels were explanted for gross and histopathologic examination.

RESULTS

Significantly shorter time-to-occlusion was achieved with the nitinol plug compared with two Gianturco coils (1.73 minutes +/- 1.28 vs 5.73 minutes +/- 6.18; P = .021). The recanalization rate at 1 month was also significantly lower (36.4% vs 81.8%, P = .027). The occlusion time was strongly dependent on the target artery diameter with Gianturco coils (R = .79, P = .0007), and not with the nitinol plug.

CONCLUSION

The nitinol vascular occluder appears highly effective and reliable, with one plug resulting in significantly faster and longer lasting occlusions compared with two Gianturco coils. The new device can be repositioned prior to release, therefore allowing optimal positioning.

Occlusion of the neonatal patent ductus arteriosus with a simple retrievable device: a feasibility study

PURPOSE

To examine the feasibility of transvenous placement of a new memory-shaped, small, retrievable coil that has a smaller-caliber delivery system than currently available devices, for closure of the patent ductus arteriosus (PDA).

METHODS

Through 4 or 5 Fr vascular sheaths and 4 or 5 Fr end-hold catheters, the coils were delivered and placed in piglets (n = 10) with PDA. The coils were made from 0.018" (0.46 mm) or 0.028" (0.71 mm) stainless steel guidewire. Mounted for delivery, the new device has the appearance of a conventional guidewire. This neonatal PDA model was created without major surgery or drugs by stenting the ductus arteriosus.

RESULTS

The memory-shaped coils were easily delivered. Coils not optimally placed were retrieved and repositioned. Occlusion of the ductus arteriosus as early as a half-hour after delivery was shown angiographically and confirmed by histopathology.

CONCLUSION

This new, small-caliber, simple device was found to be effective for closure of the PDA in this animal model. Longer-term observations are needed.

New Gianturco-Grifka vascular occlusion device. Initial studies in a canine model

BACKGROUND

Transcatheter closure of cardiovascular defects remains a challenge. Several occlusion devices are available, but each device has limitations. The purpose of this study was to evaluate the new Gianturco-Grifka vascular occlusion device (GGVOD) in a canine model.

METHODS AND RESULTS

A total of 26 GGVODs were implanted as part of short- and long-term studies. In the short-term study, 1 GGVOD was implanted in each of 11 systemic arteries from 3.2 to 9.0 mm in diameter. All 11 arteries were occluded immediately. In the long-term study, an aortopulmonary shunt was placed in 10 dogs (9, Gore-tex graft; 1, subclavian artery) followed by GGVOD implantation; additionally, a GGVOD was implanted in 5 subclavian arteries. The dogs were boarded for 3 to 6 months, then recatheterized and euthanatized. Immediately after implantation, the 5 subclavian arteries and 9 Gore-tex shunts were occluded completely; the 1 subclavian artery shunt had a small residual leak. At recatheterization, all 10 shunts and 5 subclavian arteries were occluded completely. Necropsy revealed all shunts to be occluded, with the aortic and pulmonic orifices covered with a neointimal layer. The mean fluoroscopic time needed for GGVOD implantation was 9 minutes (range, 3 to 22 minutes).

CONCLUSIONS

(1) In a canine model, the GGVOD is effective for transcatheter occlusion of arteries and aortopulmonary shunts from 3 to 9 mm in diameter. Possible indications in children include aortopulmonary collateral vessels, long patent ductus arteriosus, systemic-pulmonary shunts, AV malformations, and arteries supplying tumors. (2) GGVOD implantation requires a short fluoroscopic time.

Transcatheter occlusion of patent ductus arteriosus with adjustable buttoned device. Initial clinical experience

BACKGROUND

Several devices are available for transcatheter occlusion of patent ductus arteriosus. Most of these devices either require complicated intracardiac maneuvering, have not been tried in humans, or need a large-sized sheath for implantation of the device.

METHODS AND RESULTS

During a 26-month period ending November 1992, 14 patients underwent transcatheter closure of patent ductus arteriosus with an adjustable buttoned device delivered via a 7F sheath under an institutional review board-approved custom-made device protocol. The children were 15 months to 8 years of age with weight range of 7.2 to 19 kg. The patent ductus arteriosus measured from 2 to 7.5 mm (median, 3 mm) at the narrowest diameter and was conical, short, or tubular. They were occluded with devices measuring 15 to 20 mm. The ratio of pulmonary to systemic flow decreased (P < .01) from 1.9 +/- 0.6 (mean +/- SD; range, 1.3 to 3.2) to 1.05 +/- 0.1 (1 to 1.3). Continuous murmur of patent ductus arteriosus disappeared in all except 1 patient. Small residual shunts were detected by color Doppler studies in 4 of 14 patients (29%). All patients were followed for 1 to 24 months (mean, 6 +/- 7 months). The device was intact in all patients, and no breakage of the wires was noted. No shunts were seen in 12 of 14 patients (86%), and minute residual shunts were seen in 2 children. No major complications were encountered.

CONCLUSIONS

It is concluded that transcatheter closure of patent ductus arteriosus with the adjustable buttoned device is feasible and effective and can be accomplished via small 7F sheaths; a 7F sheath is adequate for all ductal sizes; and the adjustable length of the loop accommodated all types of patent ductus arteriosus. Clinical trials on a larger number of patients are warranted.