Validation of Myocardial Acceleration During Isovolumic Contraction as a Novel Noninvasive Index of Right Ventricular Contractility (original) (raw)
Related papers
Circulation, 2003
Background-We have demonstrated that myocardial acceleration during isovolumic contraction (IVA) is a sensitive index of right ventricular contractile function. In this study, we assessed the usefulness of IVA to measure left ventricular (LV) contractile function and force-frequency relationships in an experimental preparation. Methods and Results-In study 1, we examined 6 pigs by use of tissue Doppler imaging of LV free wall and simultaneous measurements of intraventricular pressure, volume, maximal elastance (E max ), and dP/dt max by conductance catheterization. Animals were paced via the right atrium at a rate of 130 bpm. IVA was compared with elastance during contractility modulation by esmolol and dobutamine and assessed during preload reduction and afterload increase. In study 2, in 6 more pigs, force-frequency data were obtained during incremental atrial pacing from 120 to 180 bpm. Study 1: Esmolol led to a decrease in IVA and E max (PϽ0.03 and Ͻ0.02, respectively), both of which increased during dobutamine infusion (PϽ0.02 and Ͻ0.03, respectively). IVA was unaffected by significant (PϽ0.001) acute reduction of LV volume and a significantly increased LV afterload (systolic pressure increase, PϽ0.001). Study 2: There was a positive correlation between IVA and dP/dt max (r 2 ϭ0.92, PϽ0.05). As heart rate was increased from 120 to 160 bpm, there were significant increases in both IVA and dP/dt max (PϽ0.0004 and Pϭ0.02, respectively). Over the same range of heart rates, there was no significant change in E max (Pϭ0.22). Conclusions-IVA is a measurement of LV contractile function that is unaffected by preload and afterload changes within a physiological range and can be used noninvasively to measure LV force-frequency relationships. (Circulation. 2003; 107:1647-1652.)
Myocardial Acceleration During Isovolumic Contraction
Circulation, 2005
Background— Acceleration of the mitral ring during isovolumic contraction has been proposed as a load-independent index of global left ventricular (LV) contractility. This study investigates whether myocardial isovolumic acceleration (IVA) reflects regional contractility. Methods and Results— In acutely instrumented, anesthetized dogs, we measured LV pressure, myocardial long-axis velocities, and IVA by tissue Doppler imaging (TDI) and sonomicrometry at different levels of global LV contractility and preload and during regional myocardial ischemia (reduced flow in the left anterior descending coronary artery). Dobutamine caused dose-dependent increments in IVA from 3.6±0.6 (mean±SEM) to a maximum of 7.1±1.4 m/s 2 ( P <0.01) by TDI, and there were parallel increments in LV dP/dt max ( P <0.01). However, volume loading decreased IVA from 3.6±0.6 to 2.5±0.4 m/s 2 ( P <0.05), whereas LV dP/dt max was unchanged, and LV pressure–segment length loop analysis confirmed unchanged re...
Validation of a novel noninvasive cardiac index of left ventricular contractility in patients
AJP: Heart and Circulatory Physiology, 2007
Although there are several excellent indexes of myocardial contractility, they require accurate measurement of pressure via left ventricular (LV) catheterization. Here we validate a novel noninvasive contractility index that is dependent only on lumen and wall volume of the LV chamber in patients with normal and compromised LV ejection fraction (LVEF). By analysis of the myocardial chamber as a thick-walled sphere, LV contractility index can be expressed as maximum rate of change of pressure-normalized stress (d*/dtmax, where * ϭ /P and and P are circumferential stress and pressure, respectively). To validate this parameter, d*/dtmax was determined from contrast cine-ventriculography-assessed LV cavity and myocardial volumes and compared with LVEF, dP/dtmax, maximum active elastance (Ea,max), and singlebeat end-systolic elastance [Ees(SB)] in 30 patients undergoing clinically indicated LV catheterization. Patients with different tertiles of LVEF exhibit statistically significant differences in d*/dtmax. There was a significant correlation between d*/dtmax and dP/dtmax (d*/ dtmax ϭ 0.0075dP/dt max Ϫ 4.70, r ϭ 0.88, P Ͻ 0.01), E a,max (d*/dtmax ϭ 1.20Ea,max ϩ 1.40, r ϭ 0.89, P Ͻ 0.01), and Ees(SB) [d*/dtmax ϭ 1.60Ees(SB) ϩ 1.20, r ϭ 0.88, P Ͻ 0.01]. In 30 additional individuals, we determined sensitivity of the parameter to changes in preload (intravenous saline infusion, n ϭ 10 subjects), afterload (sublingual glyceryl trinitrate, n ϭ 10 subjects), and increased contractility (intravenous dobutamine, n ϭ 10 patients). We confirmed that the index is not dependent on load but is sensitive to changes in contractility. In conclusion, d*/dtmax is equivalent to dP/dtmax, Ea,max, and Ees(SB) as an index of myocardial contractility and appears to be load independent. In contrast to other measures of contractility, d*/dtmax can be assessed with noninvasive cardiac imaging and, thereby, should have more routine clinical applicability.
European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology, 2007
Echocardiographic techniques have so far provided suboptimal estimates of myocardial contractility in humans. Longitudinal myocardial motion during the isovolumic contraction (IVC) phase, measured by colour tissue Doppler imaging (TDI), has recently been shown in experimental animal models to reflect the state of myocardial contractility. The aim of the present study was to investigate the relationship between left ventricular (LV) isovolumic contraction velocities (IVCv) using pulsed Doppler tissue imaging (DTI) and global LV contractility as measured during cardiac catheterization. Cardiac catheterization and pulsed DTI were simultaneously performed in 16 consecutive patients (13 males, mean age 55+/-10years) with a variety of cardiac diseases. Relationships between the peak positive IVCv as measured at basal levels of the lateral, septal, anterior and posterior walls and the first derivative of LV pressure (+dP/dt(max)), were investigated. Peak IVCv measurements were obtainable i...
European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology, 2005
Echocardiographic techniques have not so far been able to provide a good estimation of myocardial contractility in humans. Myocardial motion during the isovolumic contraction phase, measured by Doppler tissue imaging, has only recently in experimental models been shown to describe myocardial contractility. The aim of the present clinical study was to investigate the relationship between right ventricular isovolumic contraction velocity and right ventricular state of contractility. Doppler tissue imaging and cardiac catheterization were performed simultaneously in 26 consecutive patients with different cardiac diseases (18 males, mean age 52 +/- 12, range 23-75 years). Peak isovolumic contraction velocity was measured using Doppler tissue imaging at 2 levels of the right ventricular free wall. During cardiac catheterization, the first derivative of right ventricular pressure related to the pulmonary artery peak pressure (dP/dt/P(max)) was measured. Furthermore, right ventricular end ...
Validation of a Novel Cardiac Index of Left Ventricular Contractility in Patients
2000
Although several excellent indices of myocardial contractility exist (e.g., dP/dt max , time varying elastance, etc.), they require accurate measurement of pressure using left ventricular (LV) catheterization. An index of contractility that is only volume-depended would enable routine clinical evaluations of the heart using current imaging modalities without the need for cardiac catheterization. The objective of this study is to validate a novel contractility index that is only dependent on lumen and wall volume of LV chamber in patients with normal and compromised LV ejection fraction (LVEF). A simplified analysis of myocardial chamber as a thick-walled sphere results in an LV contractility index expressed as the maximum rate of change of pressure-normalized stress (σ*=σ/P where σ and P are the subendocardial circumferential stress and pressure, respectively); i.e., dσ*