Zhiwen Zhou

Apex to base left ventricular twist mechanics computed from high frame rate two-dimensional and three-dimensional echocardiography: a comparison study.

BACKGROUND The aim of this study was to compare two-dimensional (2D) and three-dimensional (3D) methods for computing left ventricular (LV) rotation. METHODS A two-axis linear/rotary system was designed using rotary motors controlled through a digital interface, and 10 freshly harvested pig hearts were studied. Each heart was mounted on the rotary actuator with the base being rotated at different known degrees of rotation (10°, 15°, 20°, and 25°) and was passively driven by a pump with calibrated stoke volume (50 mL) at a constant rate (60 beats/min) simultaneously. Cardiac motion was scanned to acquire 2D short-axis views using a GE Vivid 7 system for assessing rotation, and 3D apical full-volume loops were acquired using a Toshiba Applio Artida ultrasound system. Full-volume 3D image loops were analyzed online with Toshiba Wall Motion Tracking software, and short-axis 2D images were analyzed offline for LV rotation in GE EchoPAC PC at corresponding LV levels. RESULTS At each state, both 2D and 3D echocardiography detected the changes in LV rotation but overestimated the rotation degrees. The biases for overestimation from 3D imaging were smaller compared with 2D imaging at each LV level. Both methods, when compared with each other, showed a linear correlation (r = 0.84, P < .0001). Bland-Altman comparison showed 99% of data points within range, with a constant bias between both methods (adjusted values of 3D = 1.892 + 0.964 × 3D). CONCLUSIONS Although 3D echocardiography showed smaller bias, the results between 2D and 3D echocardiography were comparable.

REGIONAL MYOCARDIAL FUNCTION AND RESPONSE TO ACUTE AFTERLOAD INCREASE IN CHRONICALLY ANEMIC FETAL SHEEP: EVALUATION BY TWO-DIMENSIONAL STRAIN ECHOCARDIOGRAPHY

We hypothesized that in chronic fetal anemia, remodeling of the myocardium is related to abnormalities in regional wall motion and acutely increased afterload further disturbs myocardial strain. Chronic anemia was induced in one fetus of each of seven sheep twin pregnancies. The fetuses were studied by two-dimensional (2-D) strain echocardiography at baseline and during increased afterload via angiotensin II (AT II) infusion. At baseline, the peak systolic longitudinal, radial and circumferential strains in the left ventricular lateral wall in anemic fetuses were lower than those in the controls (all p<0.05). During AT II, the circumferential strain of right ventricular free wall decreased significantly both in the control and anemic fetuses. Left ventricular free wall systolic strains were not affected by AT II. Fetal myocardial remodeling in chronic anemia decreases left ventricular systolic free wall strains. The myocardial adaptation does not change ventricular responses to acutely increased afterload.

3-DIMENSIONAL SPECKLE TRACKING IMAGING FOR LEFT VENTRICULAR ROTATION MEASUREMENT: AN IN VITRO VALIDATION STUDY

OBJECTIVE Left ventricular (LV) twist is manifested in oppositely directed apical and basal rotation. We studied a new 3-dimensional (3D) echocardiography program (wall motion tracking; Toshiba America Medical Systems, Inc, Tustin, CA) for left ventricular rotation. METHODS We used a rotation model with a variable-speed motor to rotate hearts in a water bath. We studied 10 freshly harvested pig hearts, which were mounted on the rotary actuator of our twist phantom with the heart base rotating and the apex held fixed to avoid translational motion, at rotations of 0 degrees , 15 degrees , 20 degrees , and 25 degrees . Full-volume 3D image loops were acquired on a Toshiba Aplio Artida ultrasound system at a maximized frame rate. RESULTS As the actual heart rotation increased, computed segmental and global rotation also increased accordingly, with the measured rotations of the basal and middle segments greater than that of the apex (both P < .001). Segmental and global rotation at all 3 levels correlated well with the actual rotation (base: r = 0.93; middle: r = 0.92; apex: r = 0.82; global: r = 0.95; all P < .001). CONCLUSIONS The new 3D program tracked LV rotation accurately.

CARDIAC TWIST BY TWO-DIMENSIONAL AND THREE-DIMENSIONAL ECHOCARDIOGRAPHY: AN IN VITRO COMPARISON STUDY

Methods: We studied 10 freshly harvested pig hearts because of their anatomical similarity with human heart. Each heart was mounted on the rotary actuator of a custom designed model and connected to a pulsatile pump through a latex balloon secured into the left ventricular (LV) cavity. Each heart was passively driven by the pump with a calibrated stoke volume (50ml) at a constant rate (60/min) and the base rotated simultaneously at 15, 20 and 25 degrees with the apex held fixed. 2D short axis views were acquired on a GE Vivid 7 Dimensions system at 7MHz. 3D apical full volume loops were acquired on a Toshiba Artida ultrasound system. The 2D images were analyzed offline for rotation in EchoPac and 3D images were analyzed online with Toshiba Wall Motion Tracking software over the full LV volume at apical and basal levels.

Diastolic untwisting is altered in patients with congenital heart disease: a novel MR speckle tracking method for cine-MRI

Methods We studied 15 pts with TOF (6 mon-45 y) post repair, 15 pts with ASD, VSD and CO (5 y-37 y) and 8 healthy adults (24-35 y). MR images were acquired with an ECG gated 1.5/3 T Magnet with segmented gradient-echo cine-loop sequences (short/long/rotated axis) to cover the entire RV and LV. Images were analyzed offline by VVI (Siemens). RV size and function was correlated for each patient). LV myocardial strain, direction of twist and untwisting, time to peak twist and length to peak diastolic untwisting were measured and compared for each patient.