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J Thorac Cardiovasc Surg 1997;113:426-427
© 1997 Mosby, Inc.

LETTERS TO THE EDITOR

Failure of devices used for the closure of atrial septal defects

Cardiovascular Division
University of Minnesota Hospital and Clinic
Minneapolis, MN 55455

To the Editor:

I read with interest the report of Agarwal, Ghosh, and Mittal ¹ on the surgical management of unsuccessful atrial septal defect (ASD) closures with the AngelWings device (Microventa Corp., White-Bear Lake, Minn.). These closures were performed by me as a part of the International ASD Closure Trial, which is being organized by the University of Minnesota to evaluate the feasibility, safety, and efficacy of a new percutaneous device ² developed at the University of Minnesota. Our preliminary clinical experience in the first 100 patients (including the six reported by Agarwal, Ghosh, and Mittal ¹) has been submitted for publication. The overall procedural success rate is 90%. We have learned a large number of lessons in the clinical use of this device from the more than 100 patients who have undergone this procedure.

The reason for emergency surgery for retrieval of errant devices has been the difficulty in retrieving the device, which is made of a nitinol alloy framework with a high tensile strength. Although we have demonstrated our ability to retrieve the device with snares in animal models, ² the stiff wire can potentially perforate cardiac chambers and systemic veins. The overriding concern in the clinical trials has been that of patient safety and hence the adoption of a policy of surgical removal of unsuccessfully deployed devices and closure of defects. We have concurrently developed a system for retrieving these devices safely. Once this is made available to participating centers, the procedural success rate will be much higher than at present and the need for emergency surgery minimized.

In these initial cases, we ¹ used device sizes twice the balloon-sized diameter. ² With experience, we have determined that we can successfully use ratios between 1.2 and 1.5, and, so long as the conjoint suture ring diameter ² is as large as the anatomic diameter of the ASD, residual shunts are uncommon. The transient complete heart block (which did not require temporary pacing) was probably related to the large-sized device used.

Percutaneous closure of ASDs in human beings, who have thin compliant atrial septa and great variability of the size and position of the defects, is more difficult than the closure of experimentally created circular defects in the thick muscular atrial septa of dogs. ² This device is self-centering and hence the anatomic criteria for selection of suitable candidates for this device is being actively investigated.

Surgical closure is the "gold standard" for the closure of ASDs. All three patients who needed emergency surgery in the series reported by Agarwal, Ghosh, and Mittal ¹ were adults. In a surgical series of 166 adult patients with ASDs, Horvath and associates ³ reported an early mortality rate of only 1.2% but a perioperative complication rate of 13%. The complications included arrhythmias necessitating cardioversion, reoperation for bleeding, air embolism, tamponade, congestive heart failure, cerebrovascular accident, transient ischemic attack, complete heart block, and respiratory failure. Obviously these two reports cannot be directly compared. In the next phase of the U.S. arm of the trials we will be formally comparing device closure and surgical closure in patients with identical entry criteria.

We hope that with greater experience in the use of this device, careful long-term follow-up, and comparison with surgical closure in a structured clinical trial, we will be able to determine the role of this new investigational device for the percutaneous closure of ASDs.

12/8/77709

References

1. Agarwal SK, Ghosh PK, Mittal PK. Failure of devices used for closure of atrial septal defects: mechanisms and management. J Thorac Cardiovascular Surg 1996;112:21-6.[Abstract/Free Full Text]
   
2. Das GS, Voss G, Jarvis G, Wyche K, Gunther R, Wilson RF. Experimental atrial septal defect closure with a new transcatheter, self-centering device. Circulation 1993;88(Suppl):1754-64.[Abstract/Free Full Text]
   
3. Horvath KA, Burke RP, Collins JJ, Cohn LH. Surgical treatment of adult atrial septal defect: early and long term results. J Am Coll Cardiol 1992;20:1156-9.[Abstract]
   

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