Long-term outcome of transcatheter patent ductus arteriosus closure using Amplatzer duct occluders
Article Outline
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 ≥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.
Percutaneous closure is an established method of treatment for most patients with patent ductus arteriosus (PDA).1 Currently, coils are the most widely used occluders for closure of small-sized PDA.2, 3 For closure of moderate- and large-sized PDA, the Amplatzer duct occluders (ADO) are the most often used.4 Immediate-, short-, and intermediate-term results of transcatheter PDA closure using ADO are excellent.4, 5, 6, 7, 8 However, long-term results of ADO implantation have not been reported to date. Therefore, the aim of this study was to evaluate long-term results of percutaneous PDA closure using ADO in a single institution.
Methods
Patient population
From September 1996 to April 2002, 64 consecutive patients having isolated PDA with a minimal diameter ≥2 mm underwent percutaneous closure using ADO and have been followed up until September 2005. Some patients were included in our previous reports.4, 9, 10 At the time of the procedure, the median patient age was 3.4 years (range 0.5-29.2 years) and weight was 15 kg (range 4.9-58 kg). Thirteen patients weighed ≤10 kg. The study was part of a clinical trial approved by an authorized ethics committee. An informed written consent was obtained from all patients or their parents.
The occluder
The Amplatzer duct occluder and delivery system (AGA Medical, Golden Valley, MN) have previously been described in detail.4, 11 In 9 patients, a modified device, an angled Amplatzer duct occluder, was implanted.10, 12
Selection of patients for transcatheter closure using Amplatzer duct occluders
The selection of patients suitable for transcatheter closure using ADO was based on minimal PDA diameter measured on aortogram. On the basis of our previous experience with percutaneous PDA closure using detachable coils, Amplatzer duct occluders were selected for closure of PDA with a minimal diameter of ≥2 mm and coils for closure of PDA with a minimal diameter of <2 mm.9
Preimplantation protocol
A physical examination, a standard 12-lead electrocardiogram, chest radiograph, and transthoracic echocardiography (TTE) were performed in all patients.
Implantation procedure
The protocol for ADO implantation has previously been reported in detail.4, 10 All procedures were performed from the groin.
Follow-up protocol
Ten minutes after ADO release, a descending aortogram was performed to assess the degree of a residual shunt. A left-to-right shunt without a jet was classified as a smokelike shunt, with a jet of <2 mm in diameter as a small shunt and with a jet diameter of >2 mm as a large shunt. Pullback pressure measurements were performed to exclude obstruction of the descending aorta and left pulmonary artery.
At 24-hour follow-up, chest radiograph and TTE were performed. Both chest radiograph and TTE allowed assessment of ADO position and shape. Thrombus formation on the device was excluded by TTE. A color Doppler interrogation was performed to detect and quantify any residual shunt. A minimal color Doppler signal width of <1 mm was considered as a minimal residual shunt, 1 to 2 mm as a small residual shunt, and >2 mm as a large residual shunt. A color Doppler, pulsed Doppler, and continuous wave Doppler interrogations were performed to assess the blood flow pattern and velocity in the descending aorta and left pulmonary artery.
Follow-up TTE was performed at 1, 3, and 12 months and yearly thereafter. Throughout the follow-up period, the same TTE protocol was used. At each follow-up visit, complications related to ADO implantation were noted. Infective endocarditis prophylaxis and aspirin (5 mg/kg) were recommended for 6 months after the procedure in all patients.
Statistics
The data are expressed as mean ± SD or as median and ranges as appropriate.
Results
From September 1996 to April 2002, the transcatheter PDA closure using ADO was attempted in 64 consecutive patients having minimal PDA diameter of ≥2 mm. The implantation of the device was successful in all patients.
The mean PDA diameter was 3.5 ± 1.6 mm. Morphology of PDA was assessed and was of type A in 53 patients, type B in 1 patient, type C in 1 patient, and type E in 9 patients.13
The follow-up period ranged from 40 to 108 months (median 58 months). There were no deaths or significant complications (arterial or venous complications, device embolizations or malpositions, hemolysis, thrombus formation, thromboembolism, or infective endocarditis) during the study period.
An aortogram performed 10 minutes after ADO implantation revealed residual shunts in 26 patients (40%) and were smokelike in all of them. After 24 hours, TTE revealed a minimal residual shunt in 1 patient.
After device release, no pressure gradient was detected on pullback from the ascending aorta to the descending aorta in any patient. A Doppler interrogation performed 24 hours after the procedure revealed increased systolic blood flow velocity in the descending thoracic aorta in 2 patients: 2.7 m/s in a 1.5-year-old patient weighing 10 kg and 2.4 m/s in a 5-year-old patient weighing 14 kg. In both patients, increased blood flow velocity was confined to systole with normal diastolic blood flow velocity and normal blood flow pattern in the abdominal aorta. Four extremities blood pressure measurements failed to detect any pressure gradient in both patients.
At the end of the procedure, a pullback from the left pulmonary artery to the main pulmonary artery was performed and failed to detect pressure gradient in any patient. Twenty-four hours after the procedure, a Doppler interrogation revealed a systolic blood flow velocity of 2.5 m/s in the left pulmonary artery in a 1.5-year-old patient weighing 9 kg.
Red blood cell count routinely performed before the procedure and at discharge excluded significant mechanical hemolysis in any patient.
At 1-month follow-up visit, PDA were completely closed in all patients and remained closed throughout the follow-up period.
In both patients having increased systolic blood flow velocities in the descending thoracic aorta at 24-hour follow-up evaluation, increased velocities persisted at the last follow-up visit 4 and 5 years after the procedure, respectively. In the remaining patients, blood flow pattern in the descending thoracic aorta was normal throughout the study.
In a single patient with increased systolic blood flow velocity in the left pulmonary artery 24 hours after the procedure, blood flow velocity gradually decreased and normalized 3 years after the procedure. Blood flow pattern in the left pulmonary artery was normal in the remaining patients during the study period.
During late follow-up, no adverse events associated with implanted devices were detected in any patient.
No deformation of the implanted device or device integrity problems were detected in any patient in this study.
Discussion
This study demonstrates excellent results of transcatheter PDA closure using ADO during the follow-up period ranging up to 9.0 years.
Safety of PDA closure using ADO
Complications of transcatheter PDA closure using ADO are rare, and to date, only early complications were reported.6, 7, 8, 14, 15 No deaths or significant complications were encountered in the present study, thus confirming the safety of transcatheter PDA closure using ADO both early and during a long-term follow-up.
Death is an exceptional complication of transcatheter PDA closure using ADO reported in a single patient after device embolization to the descending aorta.6
Device embolizations or malpositions are rare after ADO implantation.6, 7, 8 Device embolizations were reported to occur immediately or within 24 hours of the procedure. Late embolizations were not reported after ADO implantation to date.
Residual high velocity jets are rare after ADO implantation, and therefore, a mechanical hemolysis is experienced exceptionally early after the procedure.14
Thrombus formation and thromboembolism were not reported after ADO implantation. To prevent thrombus formation, we recommended aspirin (5 mg/kg) for 6 months in all patients.
An infective endocarditis on an implanted ADO was not reported to date. We recommended prophylaxis for infective endocarditis for 6 months in all patients.
An aortic obstruction is a well-known complication of transcatheter PDA closure using ADO.7, 8, 15 In most patients, obstructions were clinically insignificant, detected only by Doppler echocardiography.7, 8 Furthermore, blood flow velocities decreased during follow-up.8 Exceptionally, significant obstructions were caused by protrusion of the ADO into the descending aorta, and a device removal was necessary in these patients.15 In this study, Doppler echocardiography performed 24 hours after the procedure revealed systolic blood flow velocities up to 2.7 m/s in the descending thoracic aorta in 2 of our patients and persisted in both patients at follow-up evaluations 4 and 5 years after implantation, respectively. Relatively low body weight (10 and 14 kg) contributed to the mild protrusion of the aortic disk of the device into the descending aorta. We believe that with further growth a gradual reduction of systolic blood flow velocities will occur in both patients. However, precise follow-up echocardiograms will be performed in both patients until a complete normalization of blood flow pattern in the descending thoracic aorta. To prevent protrusion of the aortic disk into the descending aorta, a modified device (an angled ADO) was implanted in 9 patients in the present study.10 Using an angled ADO, we successfully closed type A PDA with a minimal diameter of 2.1 mm in an infant weighing 4.9 kg without causing an aortic obstruction. Altogether, we successfully implanted an angled ADO in 12 patients. Implantation of the angled ADO has proved more complex comparing to the standard device. In particular, precise positioning of the angled device is necessary to ensure proper orientation of the aortic disk. Therefore, further clinical trials are necessary to confirm safety and effectiveness of the modified device.
Rarely, an obstruction of the left pulmonary artery occurs after percutaneous PDA closure using ADO.6, 8 During a 1-year follow-up period, a reduction of increased blood flow velocities was observed.8 In the present study, Doppler echocardiography performed 24 hours after the procedure revealed increased systolic blood flow velocity of 2.5 m/s in a single patient weighing 9 kg. With the patient's growth, blood flow velocity gradually decreased and normalized 3 years after the procedure.
Device integrity problems and deformations were not reported after ADO implantation to date and were not detected in the present study throughout the follow-up period.
Effectiveness of PDA closure using ADO
This study confirmed effectiveness of transcatheter PDA closure using ADO both early and during long-term follow-up. In the present study, implantation of ADO was attempted in 64 consecutive patients and was successful in all of them. Similar results were reported by other authors.5, 6, 7, 8 Smokelike shunts are frequently detected on aortogram after ADO implantation and were seen in 40% of our patients. However, a minimal residual shunt persisted after 24 hours in a single patient, and at 1-a-month follow-up, all PDAs were completely closed and remained closed thereafter. High complete closure rates, particularly at follow-up evaluations, were reported also by others.5, 6, 7, 8 For comparison, at a 1-year follow-up a complete closure in 359 (99.7%) of 360 patients was reported.8
Reopening after successful PDA coil occlusion was reported during follow-up.16 In contrast, reopening after successful ADO implantation was not reported to date and was not detected in this study.
Patent ductus arteriosus closure in infants using ADO
Reported data support the manufacturer's recommendation that ADO implantation should not be attempted in patients weighing ≤5 kg.7, 17 However, technical difficulties during implantation are frequently encountered also in infants and young children weighing ≥5 kg.17 In addition, complications are more frequent in infants and young children, particularly with large PDA.17 Aortic obstruction due to protrusion of the aortic disk of the device is possible, sometimes necessitating device removal.7, 15 Therefore, an angled ADO would be particularly suitable for this group of patients.10 An obstruction of the left pulmonary artery is also detected more frequently in infants and young children after ADO implantation. In the present study, all 3 patients with increased systolic blood flow velocities in the descending thoracic aorta or the left pulmonary artery were of a relatively low body weight (9, 10, and 14 kg). Therefore, particular attention is necessary in infants and small children, both during ADO implantation and during follow-up evaluations.
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.
References
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PII: S0002-8703(05)01066-5
doi:10.1016/j.ahj.2005.12.010
© 2006 Mosby, Inc. All rights reserved.
