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RATIONALE AND OBJECTIVES A new vascular occlusion device was tested in canine femoral and iliac arteries and in an animal model of a patent ductus arteriosus (PDA). METHODS Four variations of the vascular plug were placed into 18 iliac or femoral arteries of 17 mongrel dogs. Follow-up angiography was performed 1 hour and, if necessary, 2 hours after placement in all animals, 14 of which were then killed. Three dogs were followed angiographically for 2 weeks to 3 months. The "butterfly" plug was then tested in a canine model of a PDA. RESULTS All plugs contained thrombi, and 12 of the 18 devices caused complete or nearly complete vascular occlusion within 2 hours. In one dog, one vascular plug had eroded through the vessel wall at 3 months without clinical sequelae. Successful PDA occlusion was achieved in 1 or 2 days in 6 of 8 dogs. Three misplacements occurred, one of which resulted in death. DISCUSSION The balloon-expandable vascular plug appears to be a promising device for occlusion of blood vessels. Migration has not been observed once the device is placed, thus, sizing of the device appears less critical than with coils. However, modification of the delivery system and considerably more experience with the device are necessary to reduce the risk of misplacement.

Balloon dilatation of the ductus arteriosus was carried out in vivo in newborn pigs and on postmortem specimens from humans and piglets. The ductus was functionally closed in all newborn animals but patency resulted in all animals after balloon dilatation. Left-to-right shunts of 50% to 70% were found with anatomic lumen sizes of 3 to 5 mm. Patency was demonstrated up to 6 weeks after dilatation. Histologic examination showed splitting of the internal elastic layer and media, areas of hemorrhage confined to the media, and preservation of the adventitia. Mediastinal hemorrhage did not occur. This new technique is useful as an animal model of patent ductus arteriosus and could theoretically be used for palliative treatment of ductus-dependent congenital heart disease.

The histological changes found in the coronary arteries in 15 patients with coarctation of the aorta have been described. Qualitative and quantitative studies were performed and the results compared with the findings of a matched control group of patients without heart disease. Severe changes in the intima during early life and even the severe atheroma which appears in young persons are considered to be a reaction to coronary hypertension. The striking thickening of the media in the coronary arteries is also thought to be a reaction to the altered hemodynamic forces. In coarctation of the aorta the coronary arteries are of greater than normal capacity, and it is suggested that this histological feature parallels the increased metabolic requirements of the left ventricle.