Intracardiac phased-array imaging: methods and initial clinical experience with high resolution, under blood visualization: initial experience with intracardiac phased-array ultrasound.
OBJECTIVE
This study was designed to test the feasibility of high-resolution phased-array intracardiac imaging.


BACKGROUND
Intracardiac echocardiographic imaging of the heart during interventional electrophysiologic (EP) procedures has been limited by inadequate ultrasound penetration and absence of Doppler hemodynamic and flow information produced by rotating mechanical ultrasound elements.


METHODS
A 10F (3.2 mm) phased-array, variable 5.5 to 10 MHz frequency imaging catheter with a four-way deflectable tip was applied in 24 patients undergoing EP studies. Sixteen prespecified cardiac targets were imaged from a right heart venue.


RESULTS
Fifteen patients had no underlying organic heart disease; nine had ischemic, cardiomyopathic, valvular or congenital heart disorders. Longitudinal and short-axis imaging readily disclosed each cardiac valve, support structures and chamber, as well as the pericardium, right and left atrial appendages, the junction of the right atrium and superior vena cava, crista terminalis, tricuspid valve isthmus, coronary sinus orifice, membranous fossa ovalis and pulmonary veins. The average target depth was 8.8+/-1.5 cm (range 0.5 to 15 cm), with adequate penetration at a 7.5 MHz imaging frequency. Color flow and Doppler utilities clearly characterized transaortic and pulmonic valve and pulmonary vein blood flow, including during low output states.


CONCLUSIONS
These first human studies with this technology demonstrate the methods, feasibility and utility of intracardiac phased-array vector and Doppler imaging for long-axis, apex-to-base global cardiac imaging. High resolution of endocardial structures and catheters suggests additional utility for visualizing interventional procedures from the right heart.
Packer
Douglas L
DL
Division of Cardiology, Mayo Foundation, Rochester, Minnesota 55905, USA.
Stevens
Carolyn L
CL
Curley
Michael G
MG
Bruce
Charles J
CJ
Miller
Fletcher A
FA
Khandheria
Bijoy K
BK
Oh
Jae K
JK
Sinak
Lawrence J
LJ
Seward
James B
JB
D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging / Q000628:therapy; D001808:Blood Vessels / Q000000981:diagnostic imaging; D006328:Cardiac Catheterization / Q000295:instrumentation; D002408:Catheters, Indwelling; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000601:surgery; D006346:Heart Septum / Q000000981:diagnostic imaging / Q000601:surgery; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D014463:Ultrasonography / Q000379:methods; D018084:Ultrasonography, Interventional / Q000379:methods