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Stress echocardiography (SE) is a powerful functional imaging technique to assess cardiac performance under work conditions. The main indication is the detection of myocardial ischemia due to coronary artery disease (CAD), however it can also be used in patients with structural heart disease (e. g. valvular disease, hypertrophic obstructive cardiomyopathy). Dynamic or pharmacological (dobutamine / adenosine) modalities are available to induce cardiac stress, basically depending on the clinical problem and the patient's ability to exercise. Exercise on a treadmill or a semi-supine bicycle is the most physiological way to induce stress. Dobutamine stimulation is useful in patients who are unable to exercise and for detection of viable myocardium in hypo- or akinetic segments. Adenosin-induced hyperaemia causes steal effects in myocardial segments with significant CAD. Main limitations of SE are the need for an appropriate acoustic window and the user-dependent variability with regard to the interpretation of the results.

An uncoordinated left ventricular contraction sequence contributes significantly to the impaired hemodynamic function in patients with chronic heart failure. Cardiac resynchronization therapy with biventricular pacing may improve heart failure symptoms and exercise tolerance and reduce cardiac mortality in patients with severe chronic heart failure, depressed systolic left ventricular function (EF 120 ms. However, about one third of patients with implanted pacemakers do not respond favorably to resynchronisation therapy. This may be related to the limited diagnostic value of QRS duration for the identification of mechanical dyssynchrony. Echocardiography allows identification of mechanical dyssynchrony with a high diagnostic sensitivity and may improve the selection of patients suitable for biventricular pacing. This article discusses proposed echocrdiographic approaches for quantification of dyssynchrony.

Randomised trials involving large number of patients have demonstrated the benefits of cardiac resynchronisation therapy (CRT) in patients with heart failure who have failed optimal medical treatment. Echocardiography plays an important role in defining dyssynchrony which is key to optimal patient selection. The electrocardiographic criteria for patient selection is supplemented by the finding of dyssynchrony on Doppler myocardial imaging, and echocardiography with Doppler myocardial imaging may eventually replace the electrocardiographic criteria for selection of patients who derive benefit from CRT.