| ObjectiveTo investigate the performance of left ventricular torsion(LVtor) or twist with normal person by speckle tracking imaging (STI).Methods32 normal patients were included during the study .The objects were submitted to ECG and UCG examination to exclude hypertension, CHD and so on important heart metabolic diseases. 2D echocardiographic examination:The subjects slept on left lateral position under limb electrocardiogram supervision. We scanned the parasternal long-axis view, the apical 4- chamber and 2-chamber views, and LV short-axis views at the mitral valve, papillary muscles, and apex level, respectively. The frame rate was more than 50 every second. For each plane, 3 consecutive cardiac cycles were acquired during a breath hold, and the dynamic images were stored in a hard disk for subsequent offline analysis. We measured isovolumetric contraction time,duration of ejection,isovolumetric relaxation,early metaphase relaxation time (rapid filling time+slow filling time) and duration of atrial contraction that combined with M model.Finally, Apical ,middle and basal rotation by STI was measured from short-axis images by two-dimension strain software. LVtor was defined as net difference of left ventricular rotation (LVrot) at the apical plane LVrot at basal plane. Time of LVrot was defined as net difference of standardization time at some point of LVrot to onset.ResultsDuring isovolumic contraction period, the normal LV performed a wringing motion with a counterclockwise rotation at the base and clockwise rotation at the apex and with a clockwise rotation at the base and counterclockwise rotation at the apex in ejection period. The LVrot showed a systolic counterclockwise twist followed by a diastolic clockwise twist. Immediately after end systole, rapid untwisting developed.一,Character of LV rotation and torsionObserved from the cardiac apex to the base, at the base lever, 78.13 percent of the normal LV (25/32) performed a wringing motion with a counterclockwise rotation during isovolumic contraction period and peak value of torsion angle was 1.97°±1.62.Clockwise rotations were in ejection period. 93.75% (30/32)reached peak in end-systolic period and the peak value of torsion angle was(7.14°±3.28°). The curve returned to the baseline in relaxation period. These were displayed at picture 1,2. At the papillary muscles lever, the modes of rotation were various. Early-systolic period, the torsions were counterclockwise. Clockwise rotations alternated with counterclockwise ones during ejection and diastolic periods. The curve returned to the baseline in relaxation period. These were displayed at picture 2. At apical lever, 93.75%of torsions (30/32)showed clockwise, and peak values of torsion angles were(0.73°±0.70°)during early period of isovolumetric relaxation . During ejection period, the torsions were counterclockwise. The torsions reached the peak at end-systole and the peaks of torsion angle were(8.42°±3.53°). The curve returned to the baseline in relaxation period. These were displayed at picture 1,2.二,Comparison of peak time between normal cardiac base and apexIn isovolumic contraction period, there was no signification difference between the peak times of clockwise torsion at apex and ones of counterclockwise at base(P>0.05). In persistent contraction period, there was no signification difference between the peak times of counterclockwise torsion at apex and ones of clockwise at base(P>0.05).Conclusions1. STI can be used as a new method to assess LV torsional deformation and may have a potential ability to evaluate the relation between LV rotation and temporal sequence.2. On the basis of imaging principle and clinically domestic or overseas studies we consider that STI is of easy operation and advantage of repeat character to evaluate myocardial deformation. We will evaluate the relation of myocardial anatomy and myocardial mechanics by STI.3. During isovolumic contraction period, the normal LV performed a wringing motion with a counterclockwise rotation at the base and clockwise rotation at the apex and with a clockwise rotation at the base and counterclockwise rotation at the apex in ejection period. The LVrot showed a systolic counterclockwise twist followed by a diastolic clockwise twist. Immediately after end systole, rapid untwisting developed. Left ventricular myocardial fibers vary from a right-handed helix at the endocardium to a left-handed helix at the epicardium, LV torsion of the Endo contribute more than that of the Epi . Myocardial structure results in rotation of the LV base with respect to the apex, which accompanies rotation of myocardium under endocardium with respect to that under epicardium. At apex, rotary angles of myocardial fibers under the endocardium are more than those under the epicardium, but there is no difference at base.4. Normal volunteers time of peak rotation is unified at apex, base and ventricle. |
