To determine the frequency and factors associated with increase in microembolic signals during transcatheter closure of atrial septal defect using the Amplatzer septal occluder.

During the procedure in 16 patients, we measured microembolic signals using transcranial Doppler. Procedure time was divided into five periods: right cardiac catheterisation; left cardiac catheterisation; left cardiac angiocardiography; sizing and long sheath placement; device placement and release. We compared numbers of microembolic signals among the five periods and identified factors associated with them.

Mean size of septal occluder was 16 millimetres in diameter. Total number of microembolic signals was a median of 31.5, ranging from 3 to 113. Microembolic signals in three periods, left cardiac catheterisation; sizing, and long sheath placement; and device placement and release, were not significantly different from one another, but were significantly higher than those in the remaining two periods, right cardiac catheterisation and left cardiac angiocardiography (median was 9 in left cardiac catheterisation; 6 in sizing and long sheath placement; 6.5 in device placement and release, versus 0 in right cardiac catheterisation and 1 in left cardiac angiocardiography, p less than 0.05, respectively). Importantly, the time for device manipulation positively correlated with total number of microembolic signals (r equals 0.77, p less than 0.001), although fluoroscopic time, age, or size of septal occluder did not.

Transcatheter closure of atrial septal defect using the Amplatzer septal occluder produces microemboli, especially during device placement. To minimise the risk of systemic embolism, we must decrease the time for device manipulation.