1257: Impaired intrinsic contractility detected by echocardiographic techniques

Abstract

Speckle images are emerging new techniques for detecting and measuring cardiac mechanical dysfunction. In the past decade, the most commonly used methods to study the interaction between the ultrasound beam and the tissue speckles were the Doppler shift or power reflected from the tissue or blood cells and the radiofrequency ultrasound signal backscattered from the tissue. Ultrasonic tissue characterization (UTC) with cardiac cycle-dependent variation of integrated backscatters (IBS) has been shown as the intrinsic myocardial contractility and a potential indicator for early systolic dysfunction. Normal myocardium exhibits a cycle-dependent variation of IBS that will be blunted in the amplitude and have a temporal shift in the nadir by experimental ischemia. Reperfusing the acutely infarcted myocardium will restore the cyclic variation before the wall motion recovery, suggesting the detection of stunned myocardium. In hibernating myocardium, recent investigations have shown that the intramural contractility is relatively independent of resting wall motion and parallels contractile reserve. Using this technique, it has been demonstrated that diastolic abnormalities of left ventricular (LV) function, in arterial hypertension, are related and progress with systolic intrinsic dysfunction. Doppler tissue imaging (DTI) is another new objective method that accurately quantifies myocardial tissue velocities, deformation, time intervals and LV filling pressure. It has also been widely used for evaluating intrinsic contractility during myocardial ischemia, the reverse remodeling and improved synchronicity by simultaneously delaying regional contraction after biventricular pacing therapy in heart failure, and the assessment of LV function in different stages of chronic renal disease. In conclusion, speckle image represents a relatively new diagnostic tool, which allows integration of the conventional echocardiographic evaluation, in order to obtain specific textural parameters that reflect the myocardial ultrastructural texture and intrinsic contractility.