CRT-Ds are special defibrillators which cannot only treat a weak and fast pulse but also severe cardiac insufficiency. The acronym CRT stands for "cardiac resynchronization therapy", meaning that this device can correct uneven cardiac motion (so-called asynchronous cardiac motion) under certain conditions. These conditions are usually severe cardiac insufficiency of the left heart chamber and a total left bundle branch block (LBBB) as seen in a surface ECG. In the best-case scenario, the CRT-D can raise your quality of life and ability to withstand stress. Additionally, the CRT-D is akin to a "built-in emergency doctor" that can save your life when dangerously quick cardiac arrhythmias happen. During our follow-up appointments, we test your CRT-D's technical functionality and programming. Cardiac events recorded by the ICD and saved in its memory can be analyzed later. Certain measurements such as sensing, stimulation threshold, and impedance indicate whether the probes and the battery are in working order. When the individual settings of the device are no longer optimal for the patient's current situation, we can modify them. As a rule of thumb, CRT-D follow-up sessions are carried out every three to six months. When the ICD battery begins to run out of power, we can coordinate and conduct the replacement of the CRT-D.