No abstract

We sought to characterize the alterations of left ventricular (LV) twist after acute myocardial infarction in humans and to study their relationship to usual parameters of LV function. Systolic LV twist was measured by color tissue Doppler echocardiography (TDE) in 34 patients after anterior myocardial infarction and in 20 controls. In a subset of controls and patients, the assessment of LV twist by TDE was validated against magnetic resonance (MR) tissue tagging with good agreement between the two methods. Myocardial ischemia was responsible for a decrease in LV twist in infarct patients (P < 0.01). The decrease in LV twist was correlated with the extent of the asynergic area and global LV function as assessed by LV cineangiography (P < 0.001). Thus acute myocardial ischemia is responsible for a decrease in LV twist that is related to global LV function. Color TDE is a promising technique for straightforward assessment of LV twist in humans.

We report the experimental demonstration of plasma generation by time-reversal focusing. After a learning phase, the amplified time reversed signal built at a central frequency of 2.45 GHz injected in a low loss metallic cavity allows us to ignite and maintain a localized centimeter-sized plasma in argon at 133 Pa. The plasma spatial position is totally controlled by the signal waveform.