Zahid Amin

Erosion of Amplatzer septal occluder device after closure of secundum atrial septal defects: Review of registry of complications and recommendations to minimize future risk

The objectives of this study were to identify possible risk factors that may lead to erosion of the Amplatzer septal occluder (ASO) and recommend ways to minimize future risk. There have been rare occurrences of adverse events with development of pericardial effusion after ASO placement. Identification of high‐risk cases, early recognition, and prompt intervention may minimize the future risks of adverse events. In all patients who developed hemodynamic compromise after ASO placement, echocardiograms (pre‐, intra‐, and postprocedure), atrial septal defect (ASD) size (nonstretched, stretched), size of the device used, cineangiograms, and operative records were reviewed by a panel selected by AGA Medical Corporation. The findings were compared to the premarket approval data obtained from FDA‐approved clinical trials that were conducted in the United States, before the device was approved. A total of 28 cases (14 in United States) of adverse events were reported to AGA Medical. All erosions occurred at the dome of the atria, near the aortic root. Deficient aortic rim was seen in 89% and the defect described as high ASD, suggesting deficient superior rim. The device to unstretched ASD ratio was significantly larger in the adverse event group when compared to the FDA trial group. The incidence of device erosion in the United States was 0.1%. The risk of device erosion with ASO is low and complications can be decreased by identifying high‐risk patients and following them closely. Patients with deficient aortic rim and/or superior rim may be at higher risk for device erosion. Oversized ASO may increase the risk of erosion. The defect should not be overstretched during balloon sizing. Patients with small pericardial effusion at 24 hr should have closer follow‐up.Catheter Cardiovasc Interv 2004;63:496–502.

Transcatheter closure of postinfarction ventricular septal defects using the new Amplatzer muscular VSD occluder: Results of a U.S. Registry.

The objective of this study was to assess the immediate and mid‐term results of transcatheter closure of postinfarct muscular ventricular septal defects (VSDs) using the new Amplatzer postinfarct muscular VSD device (PIMVSD). Ventricular septal rupture occurs in 0.2% of myocardial infarcts and remains associated with very high morbidity and mortality. Data were prospectively collected for 18 patients who underwent attempted device closure of postinfarction VSDs between 2000 and 2003. Five patients underwent the closure in the acute phase (within 6 days from the infarct); the remaining patients underwent closure on day 14–95 after the diagnosis of the infarct. Outcome parameters included procedural success, evidence of residual shunts on echocardiography, and occurrence of procedure‐related complications. The procedure was successful in deploying a device across the VSD in 16 of 18 patients. The 30‐day mortality was 28%. Eleven patients are still alive and have been followed up for a median of 332 days. Two patients required a second procedure to close a residual VSD. At the most recent outpatient follow‐up, the VSD was completely closed in two patients, six patients had a trivial or small residual shunt, and two patients had a moderate residual shunt. We conclude that percutaneous device closure of postinfarction VSDs using the Amplatzer PIMVSD occluder appears to be safe and effective. Further trials are required to assess long‐term efficacy and compare the results with those of surgical closure. Catheter Cardiovasc Interv 2004;61:196–201.

Procedural Results and Acute Complications in Stenting Native and Recurrent Coarctation of the Aorta in Patients Over 4 Years of Age: A Multi-Institutional Study

Background: We report a multi‐institutional experience with intravascular stenting (IS) for treatment of coarctation of the aorta. Methods and Results: Data was collected retrospectively by review of medical records from 17 institutions. The data was broken down to prior to 2002 and after 2002 for further analysis. A total of 565 procedures were performed with a median age of 15 years (mean = 18.1 years). Successful reduction in the post stent gradient (<20 mm Hg) or increase in post stent coarctation to descending aorta (DAo) ratio of >0.8 was achieved in 97.9% of procedures. There was significant improvement (P < 0.01) in pre versus post stent coarctation dimensions (7.4 mm ± 3.0 mm vs. 14.3 ± 3.2mm), systolic gradient (31.6 mm Hg ± 16.0 mm Hg vs. 2.7 mm Hg ± 4.2 mm Hg) and ratio of the coarctation segment to the DAo (0.43 ± 0.17 vs. 0.85 ± 0.15). Acute complications were encountered in 81/565 (14.3%) procedures. There were two procedure related deaths. Aortic wall complications included: aneurysm formation (n = 6), intimal tears (n = 8), and dissections (n = 9). The risk of aortic dissection increased significantly in patients over the age of 40 years. Technical complications included stent migration (n = 28), and balloon rupture (n = 13). Peripheral vascular complications included cerebral vascular accidents (CVA) (n = 4), peripheral emboli (n = 1), and significant access arterial injury (n = 13). Older age was significantly associated with occurrence of CVAs. A significant decrease in the technical complication rate from 16.3% to 6.1% (P < 0.001) was observed in procedures performed after January 2002. Conclusions: Stent placement for coarctation of aorta is an effective treatment option, though it remains a technically challenging procedure. Technical and aortic complications have decreased over the past 3 years due to, in part, improvement in balloon and stent design. Improvement in our ability to assess aortic wall compliance is essential prior to placement of ISs in older patients with coarctation of the aorta.

Comparison of surgical, stent, and balloon angioplasty treatment of native coarctation of the aorta: an observational study by the CCISC (Congenital Cardiovascular Interventional Study Consortium).

OBJECTIVES The purpose of this study was to compare the safety and efficacy of surgical, stent, and balloon angioplasty (BA) treatment of native coarctation acutely and at follow-up. BACKGROUND Controversy surrounds the optimal treatment for native coarctation of the aorta. This is the first multicenter study evaluating acute and follow-up outcomes of these 3 treatment options in children weighing >10 kg. METHODS This is a multicenter observational study. Baseline, acute, short-term (3 to 18 months), and intermediate (>18 months) follow-up hemodynamic, imaging data, and complications were recorded. RESULTS Between June 2002 and July 2009, 350 patients from 36 institutions were enrolled: 217 underwent stent, 61 underwent BA, and 72 underwent surgery. All 3 arms showed significant improvement acutely and at follow-up in resting systolic blood pressure and upper to lower extremity systolic blood pressure gradient (ULG). Stent was superior to BA in achieving lower ULG acutely. Surgery and stent were superior to BA at short-term follow-up in achieving lower ULG. Stent patients had shorter hospitalization than surgical patients (2.4 vs. 6.4 days; p < 0.001) and fewer complications than surgical and BA patients (2.3%, 8.1%, and 9.8%; p < 0.001). The BA patients were more likely to encounter aortic wall injury, both acutely and at follow-up (p < 0.001). CONCLUSIONS Stent patients had significantly lower acute complications compared with surgery patients or BA patients, although they were more likely to require a planned reintervention. At short-term and intermediate follow-up, stent and surgical patients achieved superior hemodynamic and integrated aortic arch imaging outcomes compared with BA patients. Because of the nonrandomized nature of this study, these results should be interpreted with caution.

Intermediate follow‐up following intravascular stenting for treatment of coarctation of the aorta

Background: We report a multiinstitutional study on intermediate‐term outcome of intravascular stenting for treatment of coarctation of the aorta using integrated arch imaging (IAI) techniques. Methods and Results: Medical records of 578 patients from 17 institutions were reviewed. A total of 588 procedures were performed between May 1989 and Aug 2005. About 27% (160/588) procedures were followed up by further IAI of their aorta (MRI/CT/repeat cardiac catheterization) after initial stent procedures. Abnormal imaging studies included: the presence of dissection or aneurysm formation, stent fracture, or the presence of reobstruction within the stent (instent restenosis or significant intimal build‐up within the stent). Forty‐one abnormal imaging studies were reported in the intermediate follow‐up at median 12 months (0.5–92 months). Smaller postintervention of the aorta (CoA) diameter and an increased persistent systolic pressure gradient were associated with encountering abnormal follow‐up imaging studies. Aortic wall abnormalities included dissections (n = 5) and aneurysm (n = 13). The risk of encountering aortic wall abnormalities increased with larger percent increase in CoA diameter poststent implant, increasing balloon/coarc ratio, and performing prestent angioplasty. Stent restenosis was observed in 5/6 parts encountering stent fracture and neointimal buildup (n = 16). Small CoA diameter poststent implant and increased poststent residual pressure gradient increased the likelihood of encountering instent restenosis at intermediate follow‐up. Conclusions: Abnormalities were observed at intermediate follow‐up following IS placement for treatment of native and recurrent coarctation of the aorta. Not exceeding a balloon:coarctation ratio of 3.5 and avoidance of prestent angioplasty decreased the likelihood of encountering an abnormal follow‐up imaging study in patients undergoing intravascular stent placement for the treatment of coarctation of the aorta. We recommend IAI for all patients undergoing IS placement for treatment of CoA.

Intraoperative closure of muscular ventricular septal defect in a canine model and application of the technique in a baby

Isolated muscular ventricular septal defects (VSDs) account for 10% of VSDs. Among these, inlet and midmuscular VSDs are relatively easy to approach surgically, but apical and anterior muscular VSDs can be difficult to visualize during the operation. 2 Intraoperative closure of muscular VSDs with a device during cardiopulmonary bypass (CPB) has been described with good results. The current report describes the use of a new transcatheter device to close muscular VSDs intraoperatively without using CPB in three dogs and later in an 8-month-old girl. Animal studies. The Amplatz VSD device (AGA Medical Corporation, Golden Valley, Minn.) is a modified version of the Amplatz septal occlusion device. It is made of fine nitinol wires that are woven into two discs with a connecting waist. The discs are filled with polyester to enhance thrombogenicity. The device is custom built to correspond to the size of the VSD and thickness of the ventricular septum. It has a screw mechanism on one side for connection to the delivery cable. The device is withdrawn into a loader before introduction into the delivery sheath. All animals received humane care in compliance with the “Guide for the Care and Use of Laboratory Animals” (NIH Publication No. 86-23, revised 1985). The study protocol was approved by institutional animal care committee of the University of Minnesota. To determine the feasibility of intraoperatively closing muscular VSDs, we created an anterior or apical VSD in three dogs with the help of a punch device. The diameter of the punch device was 10 mm. With the animal under general endotracheal anesthesia and aseptic technique, the chest was entered by median sternotomy. The pericardium was opened. Two stay stitches were applied on the right ventricular free wall. A purse-string suture was placed on the left atrial appendage. The index finger of the left hand was inserted in the left atrium and advanced in the left ventricle. A right ventriculotomy was performed and the punch device inserted through the incision in the right ventricle. With a burring action, the septum was traversed until the punch device touched the index finger in the left ventricle. The punch was locked and removed, and the right ventriculotomy was closed with 5-0 running Prolene suture (Ethicon, Inc., Somerville, N.J.). The size of the defect was measured by epicardial echocardiography. In one dog two VSDs were created. An Amplatz VSD device that corresponded to the size of the VSD was screwed onto the delivery cable and withdrawn with the delivery sheath immersed in saline solution to avoid entrapment of air bubbles. The sheath was pushed through the right ventricular free wall. With the aid of epicardial echocardiographic guidance the sheath was aimed toward the muscular VSD. Once the sheath was across the VSD, the left disc was deployed in the left ventricle. The sheath was withdrawn and the right disc deployed in the right ventricle. The device was disconnected from the cable by counterclockwise rotation of the cable. Residual shunt was checked with the help of epicardial echocardiography. Results. A total of four VSDs were created in three dogs. The smallest measured 7 mm and the largest 11 mm. Three muscular VSDs were closed during the operation and the fourth one in the catheterization laboratory. The first dog died 2 hours after the operation because of ventricular fibrillation. Dissection of the heart revealed the device in good position. The second dog was put to death after 3 months. Examination of the heart revealed the device in the optimal location with complete endothelialization. The third dog (with two devices) is still alive. Six months’ follow-up echocardiogram and angiogram revealed no shunt. Muscular VSDs in an 8-month-old baby. The operation was done on the basis of compassionate need. Informed consent and approval of the Institutional Review Board of the University of Minnesota, Minneapolis, were obtained before placement of the device. Baby A was born with multiple muscular VSDs (anterior and apical muscular) and coarctation of aorta. She underwent repair of aortic coarctation and pulmonary artery banding on the fourth day of life. At the age of 8 months she had debanding with closure of large muscular VSDs. Postoperatively a significant residual shunt was identified, but the VSD could not be located during CPB. From the Departments of Cardiology and Cardiovascular Surgery, University of Minnesota, Minneapolis, Minn., and Department of Cardiology, Children’s Memorial Medical Center, Northwestern University Medical School, Chicago, Ill.

New device for closure of muscular ventricular septal defects in a canine model

BACKGROUND Repair of muscular ventricular septal defects (MVSDs) has always been challenging to the surgeon. Long-term morbidity and mortality are significantly increased if the defects are closed via left ventriculotomy or if they are associated with other complex congenital anomalies. The purpose of this study was to close MVSDs with the Amplatz ventricular septal defect device. This device is constructed from 0.004-in nitinol wire mesh filled with polyester fibers. It is retrievable, repositionable, self-centering, and of low profile. METHODS AND RESULTS MVSDs were created with the help of a sharp punch in 10 dogs. The location of the defects was anterior muscular (n=3), midmuscular (n=3), apical (n=3), and inlet muscular (n=1). The diameter of the defects ranged from 6 to 14 mm. All defects were closed in the catheterization laboratory. The device was placed with the help of transesophageal echocardiography and fluoroscopy. A 7F sheath was used to deploy the device from the right ventricular side in 8 and the left ventricular side in 2 dogs. Placement was successful in all animals. The complete closure rate was 30% (3/10) immediately after placement and 100% at 1-week follow-up. Pathological examination of the heart revealed complete endothelialization of the device in dogs killed after 3 months. CONCLUSIONS The Amplatz ventricular septal defect device appears highly efficacious in closing MVSDs. The advantages include a small delivery sheath, complete retrievability before release, and the fact that it is self-centering and self-expanding, thereby making it an attractive option in smaller children.

Transcatheter closure of secundum atrial septal defects

The atrial septum is composed of septum primum and septum secundum. The septum primum, also known as the septum ovale, is the thin portion of the atrial septum that is cradled by the septum secundum, also known as the thick portion of the atrial septum. Secundum atrial septal defect (ASD) is a defect in the septum primum. It is the most common type of ASD. These defects can range in size from a tiny perforation of the atrial septum (small ASD) to complete absence of the atrial septum (large ASD). Sometimes, in large defects, the septum secundum may also be deficient, making transcatheter closure of the ASD challenging.

Transcatheter closure of membranous ventricular septal defects with a new nitinol prosthesis in a natural swine model.

Transcatheter closure of a membranous ventricular septal defect (MVSD) is much more difficult than closure of other intracardiac defects because of the proximity to the aortic and tricuspid valves and their relatively large size in small children. In this report, transcatheter closure of naturally occurring membranous VSDs was attempted in 12 Yucatan minipigs. The prosthesis is constructed from fine Nitinol wires in the shape of two buttons and a connecting waist filled with polyester fiber. Two kinds of prosthesis were used in this study: concentric and eccentric left‐sided retention disks. A 6 or 7 Fr delivery sheath was advanced across the membranous VSD over a wire from femoral vein. The prosthesis was inserted through the sheath by pushing the delivery cable to deploy a button into left ventricle and the second button was then deployed into right ventricle by withdrawing the sheath. Successful implantation of the device was achieved in all animals except one. Complete closure rate was 58.3% immediately after placement, 100% at 1 week, 90.9% at 1 month and 3 months, and 100% at 6 months. An associated aneurysm of the membranous septum increased significantly in size in two of three animals using the concentric device, and in none of the animals using the eccentric device. A trace to mild aortic regurgitation was present in two of the three animals using the concentric device, and only in one of the eight animals using the eccentric device. Five animals developed a trace to mild tricuspid regurgitation. Pathologic examination showed all devices to be covered by smooth neoendothelium at 3 months. This report presents the first experimental study where closure of membranous ventricular septal defects in a swine model was attempted by specially constructed devices. Procedural success and occlusion rates are very encouraging but overall results cannot equal surgery. Further experimentation is needed with devices that are redesigned according to the experience gained from this study. Cathet. Cardiovasc. Intervent. 50:502–509, 2000.

PFO closure complications from the AGA registry

Objectives: To evaluate all complications that occurred during or after cardiac catheterizations for Amplatzer PFO device closure of patent foramen ovale (PFO), determine the cause of the complications and recommend techniques to minimize complications in the future. Background: Rare complications were reported to the manufacturer of the Amplatzer PFO occluder since the introduction of the device. Methods: A panel of independent physicians reviewed all complications reported to the manufacturer to determine whether the complication was related to the device or related to the cardiac catheterization procedure. Demographic data, echocardiograms, operative reports, and time to occurrence of complications were reviewed. Results: A total of 11 events were reported. Only two patients had device related complications (erosion), an incidence of 0.018%. Two patients were found to have additional atrial septal defect after PFO closure. Two patients were thought to have an inflammatory reaction without any serious sequelae. Five complications were related to the cardiac catheterization procedure (atrial appendage perforation). Conclusions: Device related complications after Amplatzer PFO occluder placement are extremely rare. Cardiac catheterization related complications appear to be the most common cause of the hemodynamic compromise. Careful manipulation of catheters and wires, recognition of the location of the catheter by fluoroscopy and echocardiography will decrease the risk of such complications.