3. Materials and methods - 3 studies. All patients are examined by echocardiography 2-dimensional, M-mode, 3-dimensional and with tissue harmonic imaging. Study 1) Patients with AV-conduction disorder that needs pacemaker treatment are randomized to DDD-pacemaker or biventricular pacemaker. Study 2) Patients with sick sinus syndrome included in DANPACE are randomized to AAI- or DDD-pacemaker. Study 3 ) Acute study to examine the changes in patients AV-block before DDD-pacemaker implantation and after implantation.