Myocardial tissue Doppler echocardiography (TDE) has been proposed as a tool for the assessment of diastolic function. Controversy exists regarding whether TDE measurements are influenced by preload. In this study, left ventricular volume and high-fidelity pressures were obtained in eight closed-chest dogs during intermittent caval occlusion. The time constant of isovolumic ventricular relaxation (τ) was altered with varying doses of dobutamine and esmolol. Peak early diastolic myocardial (Em) and transmitral (E) velocities were measured before and after preload reduction. The relative effects of changes in preload and relaxation were determined for Em and compared with their effects on E. The following results were observed: caval occlusion significantly decreased E (ΔE = 16.4 ± 3.3 cm/s, 36.6 ± 13.7%, P < 0.01) and Em (ΔEm = 1.3 ± 0.4 cm/s, 32.5 ± 26.1%,P < 0.01) under baseline conditions. However, preload reduction was similar for E under all lusitropic conditions (P = not significant), but these effects on Em decreased with worsening relaxation. At τ < 50 ms, changes in Em with preload reduction were significantly greater (ΔEm = 2.8 ± 0.6 cm/s) than at τ= 50-65 ms (ΔEm = 1.2 ± 0.2 cm/s) and at τ>65 ms (ΔEm = 0.5 ± 0.1 cm/s, P < 0.05). We concluded that TDE Em is preload dependent. However, this effect decreases with worsening relaxation.
- Diastolic function
- Tissue Doppler echocardiography
- Ventricular relaxation
ASJC Scopus subject areas
- Physiology (medical)