Implementing cardiac resynchronization therapy in routine clinical practice: preoperative considerations and implantation techniques.

Cardiac resynchronization therapy (CRT) using coronary sinus (CS) leads is an established therapy for congestive heart failure in patients with asynchronous ventricular contractions. CRT improves not only exercise tolerance but also the patient's prognosis. Appropriate patient selection for CRT is essential for a successful therapeutic response. Inclusion criteria are based on symptoms (New York Heart Association classes III and IV), a reduced ejection fraction, and a widened QRS complex. The presence of objective markers of heart failure can be considered a prerequisite for successful CRT. CRT procedures are much longer than regular pacemaker implantations, and thus the risk of infection may be greater. Successful therapy depends on the placement of left ventricular leads, usually via the CS, which is a technically more challenging procedure than regular pacemaker implantations. Complications specific to CRT include ventricular arrhythmia, such as ventricular tachycardia or ventricular fibrillation; total atrioventricular block or sinus arrest without any escape rhythm; and CS dissection.