Consider Pulsatile Motions When Sizing Aortic Endografts

BY ROBERT FINN

SCOTTSDALE, ARIZ. -- A study of pulsatile motions in the aorta has revealed that the vessel varies in diameter by at least 10% during the cardiac cycle, and by as much as 20% in some patients. This surprising degree of size variation has important implications for the sizing and durability of aortic endografts, Dr. Joffrey van Prehn said at an international congress on endovascular interventions sponsored by the Arizona Heart Institute.

Using cinematographic CT angiography, Dr. van Prehn, of University Medical Center, Utrecht, the Netherlands, also documented 6-mm changes in the aorta's center of mass.

These results suggest that the standard practice of oversizing endografts by 10% may not be adequate in some patients. Furthermore, the movements in the aorta's center of mass may mean that endografts are subject to larger-than-expected mechanical stresses.

The study involved 15 patients who were imaged by a 64-slice Philips Brilliance CT. Using standard radiation and contrast, the investigators obtained eight 64-slice images per cardiac cycle as the patients held their breath for 20 seconds.

The investigators made diameter and center-of-mass calculations at three sites on the ascending aorta and at two sites on each of the innominate, left subclavian, and left carotid arteries.

Changes in the diameter of the ascending aorta during the cardiac cycle were statistically significant and were an average of at least 10% at all three levels, with the greatest amount of change at the most proximal site, 5 mm distal to the coronaries.

Movement of the aorta's center of mass also increased from distal to proximal. All three side branches of the aortic arch showed center-of-mass movements of 2-2.5 mm.

Dr. van Prehn concluded that these dynamics must be considered when selecting, sizing, and designing aortic endografts.