page_title: Pacemaker syndrome
section_title: Causes
hierarchical_section_title: Pacemaker syndrome / Causes
context_page_description: Pacemaker syndrome is a condition that represents the clinical consequences of suboptimal atrioventricular synchrony or AV dyssynchrony, regardless of the pacing mode, after pacemaker implantation.
  It is an iatrogenic disease—an adverse effect resulting from medical treatment—that is often underdiagnosed. In general, the symptoms of the syndrome are a combination of decreased cardiac output, loss of atrial contribution to ventricular filling, loss of total peripheral resistance response, and nonphysiologic pressure waves.
  Individuals with a low heart rate prior to pacemaker implantation are more at risk of developing pacemaker syndrome. Normally the first chamber of the heart contracts as the second chamber is relaxed, allowing the ventricle to fill before it contracts and pumps blood out of the heart. When the timing between the two chambers goes out of synchronization, less blood is delivered on each beat. Patients who develop pacemaker syndrome may require adjustment of the pacemaker, or fitting of another lead to better coordinate the timing of atrial and ventricular contraction.
context_section_description: The cause is poorly understood. However several risk factors are associated with pacemaker syndrome.
caption: ECG of pacemaker syndrome