Cardiac resynchronisation One of the advances for heart insufficiency developed over the past few years has been the incorporation of biventricular pacemakers and defibrillators. Known as cardiac resynchronisation therapy, their implantation provides the advantage of increasing the performance of the heart in a number of patients with this pathology. In some cases, the heart insufficiency not only involves a loss of contractile force, but also an alteration in the synchronisation of the heart. That is to say, contraction occurs with little force and, moreover, in a disordered manner and, thus, the heart's performance or yield is notably worsened. With cardiac resynchronisation the desynchronisation of the heart contractions caused by electrical pulse disorders are minimised, and so the heart recovers part of its normal function. This results in a decrease in the symptoms, especially fatigue, and in a greater survival rate for patients. Cardiac resynchronisation therapy can be carried out in an isolated manner (with a specific pacemaker) or with a defibrillator, which also has the ability to treat the cardiac arrhythmias that can occur with some of these patients. In some cases the implantation is began in a conventional manner through the right auricle and ventricle, the left ventricle being subsequently accessed through the coronary venous system, and up to three electrodes implanted. The procedure is carried out under local anaesthetic, lasts between one and two hours and the postoperative stage is rapid, thus enabling the patient to be released in one or two days.