isovolumic contraction


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isovolumic contraction

[-vəlo̅o̅′mik]
Etymology: Gk, isos + L, volumen, paper roll, contractio, drawing together
the early phase of systole, in which the myocardial muscle fibers have begun to shorten but have not developed enough pressure in the ventricles to overcome the aortic and pulmonary end-diastolic pressures and open the aortic and pulmonary valves. During this period of muscle fiber contraction, the ventricular volumes do not change. See also afterload.
References in periodicals archive ?
20) MPI, also known as "Tei index" was calculated from IVRT, isovolumic contraction time and ejection time (15) (MPI=IVRT+isovolumic contraction time/ejection time).
On the other hand, it would be better, if they also evaluated right ventricular function using several parameters including right ventricular index of myocardial performance, tricuspid annular plane systolic excursion, and myocardial acceleration during isovolumic contraction, right ventricular fractional area change.
We can measure isovolumic contraction time, isovolumic relaxation time, and ejection time, and develop in 30 seconds not only rate, rhythm, variability but now a modified Tei index, an index of performance, and as many papers have said, an index of preload status.
Isovolumic relaxation time and isovolumic contraction time from the basal part of the left ventricle, myocardial rate during the systole, myocardial rate during the erly diastole, the rate during the late diastole, ejection time, isovolumic contraction acceleration and acceleration of the ventricle at the time of isovolumic contraction were measured.
The sensor recordings have been shown during testing and preliminary clinical trials to correlate with the force of contraction of the heart during the isovolumic contraction phase of the cardiac cycle and to the resulting recoil motion of the heart as it ejects blood into the arterial system and that these measurements of heart dynamics relate directly and predictably to heart performance.
Myocardial acceleration during isovolumic contraction (RV IVA) is defined as the peak isovolumic myocardial velocity divided by time to peak velocity and is measured by using Doppler tissue imaging at the lateral tricuspid annulus (13).
Right ventricular function can be assessed echocardiographically by using several parameters including right ventricular index of myocardial performance (RV MPI), tricuspid annular plane systolic excursion (TAPSE), myocardial acceleration during isovolumic contraction (RV IVA), right ventricular fractional area change (RV FAC), three-dimensional ejection fraction (3D RVEF), tissue Doppler-derived tricuspid lateral annular systolic velocity (Tri S), and longitudinal strain and strain rate (3).
In this study, they evaluated peak isovolu-mic velocity, isovolumic acceleration during isovolumic contraction, ejection and diastolic E and A velocities from data obtained through TTE and TEE-TDI.
Peak early filling velocity (E wave), peak atrial systolic velocity (A wave), early-to-late diastolic flow ratio (E/A), deceleration time (dTE), isovolumic relaxation time (IVRT) and isovolumic contraction time (IVCT) were measured for the tricuspid valve (26).
The relevant echocardiographic parameters were measured in both subject groups: myocardial performance index (MPI), isovolumic relaxation time (IRT), isovolumic contraction time (ICT), pre-ejection period (PEP), ejection time (ET), PEP/ET ratio, deceleration time (DT) and acceleration time (AT).
Although the entire time course of LVP cannot be converted to certain equations because of the variability in aortic properties, some equations have been proposed for isovolumic contraction and isovolumic relaxation phases, which are the periods that the aortic valve is not open, and therefore, aortic pressure is not equal to the left ventricular pressure.