Intravascular ultrasound is the new gold standard for detection of cor
onary artery disease. It is an adjunctive diagnostic procedure in card
iac catheterization laboratories. Currently, mechanical single element
s or electronic multi-element catheter-based imaging systems are avail
able with significant drawbacks either due to the long catheter drive
shaft with an external motor or the multi-element methodological probl
ems of the technology. In order to overcome the limitations of mechani
cal single element catheters, a micromotor was mounted in the distal p
art of a scanning compartment in front of a rotating mirror which refl
ected the ultrasound beam of a 30 MHz transducer. The rotation was bet
ween 3000 and 20000 rev/min, the position accuracy was +/-10 degrees,
the torque force 1-3 mu Nm, the power dissipation 10-50 mW, the diamet
er 1 mm, the length 2 mm. Cross-sectional images (360 degrees) are pro
vided. The catheter is connected to a console generating the transmiss
ion pulse, amplification of the echo signals and the envelope detectio
n of the ultrasound. The unit is interfaced with a control unit which
provides the isolated motor currents with isolated power for the elect
ronics and synchronization signals. For the first time the micromotor
tip catheter was used in a 64-year-old patient for imaging the iliac a
rtery in full length. The wall structure, the vessel lumen and even ad
jacent structures like the iliac vein could be visualized with changes
during respiration. Signs of arteriosclerosis were seen by the plaque
formation which was located eccentrically. The resolution was as high
as with conventional mechanical catheters. Most importantly, no non-u
niform rotation artefacts occurred. A micromotor system can be success
fully used for replacing the motor drive shaft of catheters which are
used for intracoronary and intravascular ultrasound and eliminate nonu
niform rotational artefacts due to friction and multiple vessel angula
tions.