Pacing stress echocardiography

Abstract

A myocardial oxygen consumption as high as that reached with exercise is not obtained by atrial pacing because cardiac volumes decrease and blood pressure does not change significantly, such that in some patients with mild coronary artery disease, wall motion abnormalities may not develop. At a high rate there are fewer video frames during the ejection period and less time to appreciate a regional wall motion abnormality. Only one-half of patients can be stressed in an atrial stimulation or biventricular mode that preserves the physiological sequence of contraction of the left ventricle. In patients with ventricular stimulation of long duration, specificity can be perhaps lowered. The external programming of the permanent pacemaker is simple and fast, but it requires technology (external programmer) and expertise not readily available in the echocardiography laboratory - with the need of minimum cooperation and coordination with the pacemaker laboratory - which is usually, but not always and anywhere, easy to obtain. Noninvasive pacemaker stress echocardiography has several advantages in comparison to conventional diagnostic techniques. The ability to instantly lower rate and terminate stress results in a high test safety. Pacemaker stress echocardiography is rapid and can be conducted at the bedside, and therefore it is well tolerated by the patient and is user-friendly for the physician. In contrast to physical stress, it does not require patient capability to exercise; contrary to pharmacological stress, it does not require an intravenous line and the additional cost (and risk) of drug administration. Imaging time is also shorter, because the median time of pacing is less than 10 min with the accelerated protocol, which compares favorably with the approximately 10 min of imaging time for dipyridamole and about 20 min for dobutamine-atropine. In patients with a permanent pacemaker, two-dimensional echocardiography during pacing is a useful tool in the detection of coronary artery disease. Because of its safety and repeatability, noninvasive pacing stress echocardiography can be the first-line stress test in patients with permanent pacemakers, especially if the stimulation can be performed in the most physiological and less technically challenging atrial or biventricular mode. © 2009 Springer Berlin Heidelberg.