New method for mechanistic studies of cardiomyoplasty: three-dimensional MRI reconstructions.
The imaging modalities used to study the mechanism of cardiomyoplasty, such as echocardiography and radionuclide scintigraphy, are seriously limited by their two-dimensional format. Radiofrequency-pulse-tagged magnetic resonance imaging was used to generate three-dimensional reconstructions of the left ventricle throughout the cardiac cycle after cardiomyoplasty. In 2 dogs that had undergone conditioned, right anterior cardiomyoplasty, wrap stimulation with alternating heartbeats was found to produce marked translation of the left ventricle in the short-axis plane, rotation around the long axis, and displacement along the long axis with net long-axis compression; there was no augmentation of radial squeeze. The findings from this study suggest that any systolic augmentation produced by the right anterior wrap is due primarily to long-axis compression. Our study demonstrates a new, more accurate technique of assessing the mechanical effects of cardiomyoplasty in three dimensions, thus permitting a more rational optimization of wrap configurations, and emphasizes the perils of using standard two-dimensional imaging modalities in this setting of exaggerated three-dimensional motion.
Cho
P W
PW
Division of Cardiac Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Levin
H R
HR
Moore
C C
CC
Tsitlik
J E
JE
McVeigh
E R
ER
Gardner
T J
TJ
Acker
M A
MA
D000818:Animals; D001243:Assisted Circulation; D006348:Cardiac Surgical Procedures; D004285:Dogs; D004558:Electric Stimulation; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D009132:Muscles / Q000637:transplantation*; D009200:Myocardial Contraction / Q000502:physiology; D010138:Pacemaker, Artificial; D012399:Rotation; D013524:Surgical Flaps; D016277:Ventricular Function, Left / Q000502:physiology; D017725:Ventricular Pressure / Q000502:physiology