Strategies for restoring cardiac synchrony by cardiac pacing

Abstract

As already demonstrated, the restoring of cardiac synchrony is a complex process which implies a detailed assessment of the pathology that needs to be restructured (such as cardiac conduction abnormalities, heart failure) and a particularized analysis of pacing alternatives. In brief, this predecisional analysis involves the anticipation of the hemodynamic response for each type of cardiac pacing. The two most corrected pacing parameters are the atrioventricular and interventricular delay; however, their optimization process is often difficult because of the lack of an exclusive pacing system optimization by which the cardiac parameters can be improved. In general, the optimization methods are classified as echocardiographic and non-echocardiographic methods, but the most used is the echocardiographic evaluation. Cardiac resynchronization therapy is basically the pacing of the free wall region of the left ventricle with a lead. It is of interest that the transvenous approach is the most frequently utilized method. Even so, the right ventricle apex lead insertion may have negative effects on the cardiac function as a result of negative effects on myocardial contractility. Conversely, the left ventricle lead insertion may have variable effects that depend on various factors such as coronary sinus anatomy, the degree of atrioventricular and interventricular dyssynchrony, and location of scars due to myocardial infarction. Lastly, cardiac pacing is the key element for assessing the responder or nonresponder status in case of patients diagnosed with heart failure, being achieved by a team that includes an electrophysiologist and a specialist in cardiac hemodynamic assessment by echocardiography.