A new instrument for surgical creation of an atrial septal defect

An instrument for surgical creation of an atrial septal defect (ASD) was designed and tested in puppies weighing an average of 4.7 kg. Oxygen saturations were obtained in both atria, the superior vena cava, and the inferior vena cava before and after septectomy. The instrument has a cutting cylinder introduced into the right atrium (RA) through the right atrial appendage with a second part (base-plate) inserted into the left atrium (LA) just posterior to the interatrial groove. In 21 animals (Group 1), a single hole was created in dogs killed 48 hours later. In 9 animals (Group 2), an attempt was made to create two adjoining holes. In 14 animals (Group 3), a single hole was created and the dogs were allowed to triple their body weight before they were killed. Group 1 dogs demonstrated a 10% increase in average venae cavae--RA oxygen saturation immediately after septectomy and a 9.4 +/- 0.37 mm diameter of the ASD at death; in Group 2, there was a 14% average step-up and a 12.7 +/- 0.6 mm diameter of the ASD; and in Group 3, the diameter of the ASD was 11.5 +/- 0.4 mm, representing a 50% increase in average area with dog growth compared with that of Group 1. After this experience in the production of ASDs in 44 experimental animals, we find that this instrument seems to be reliable, simple, and safe.