<unk>  is a condition that represents the clinical consequences of suboptimal atrioventricular (AV) synchrony or AV dyssynchrony, regardless of the pacing mode, after<unk>  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<unk>  implantation are more at risk of developing<unk> . Normally the first chamber of the heart (atrium) contracts as the second chamber (ventricle) 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<unk>  may require adjustment of the<unk> , or fitting of another lead to better coordinate the timing of atrial and ventricular contraction.
Pacemaker syndrome
Pre-excitation syndrome
Takotsubo cardiomyopathy
Torsades de pointes
Primary ventricular fibrillation
Aicardi syndrome
Unstable angina
Sudden arrhythmic death syndrome