Umbrella catheter for nonoperative closure of atrial septal defects.

: Since a 1974 report of nonoperative closure of atrial septal defects (ASDs) using an umbrella catheter device, an additional 25 dogs have undergone creation of atrial septal defects, 12 of which have subsequently had successful transvenous closure. An improved model of the closure device has been developed, still using a pair of interlocking umbrella-like components made of stainless steel and Dacron. The umbrellas are smaller, lighter, and have an automatic opening ring. They are loaded simultaneously into a single capsule on the distal end of the outer catheter and are passed into the heart on a single passage, thus eliminating several steps of the original technique. Closure time has diminished from an average of 30 minutes to 5-10 minutes. The completeness of closure was documented in 12 animals by repeat cardiac catheterization which included hydrogen electrode studies. Autopsies on 10 sacrificed dogs revealed no adverse effects or migration of the device; two dogs are living and healthy. In the one clinical application, the patient has done well, remaining afebrile with an increased activity tolerance and resumption of normal activities. The umbrella has remained in position and appears to be functioning well.