Related Experiment Video
Updated: Jun 19, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Adrenergic stimulation increases repolarization dispersion and reduces activation-repolarization coupling along the
Raja J Selvaraj1, Adrian M Suszko, Anandaraja Subramanian
1Division of Cardiology, University Health Network, Toronto, Canada.
Aims:
Dispersion of repolarization (DOR) in the human heart is minimized by activation-repolarization coupling. Adrenergic stimulation can be proarrhythmic in patients with impaired left-ventricular function and its effect on repolarization dispersion has not been systematically investigated. Our objective was to study the effect of dobutamine on repolarization dispersion and activation-repolarization coupling in patients with cardiomyopathy.
Methods And Results:
Activation recovery intervals (ARI) and activation times (AT) were measured from unipolar electrograms at 10 sites along the apicobasal right ventricle (RV) in 14 patients with cardiomyopathy (LVEF < 40%). These measurements were made during control, dobutamine 2.5-5.0 microg/kg/min, and a recontrol phase while maintaining constant heart rates with atrial pacing. Dispersion of repolarization was calculated from the total recovery time (TRT, AT+ARI). Activation-repolarization coupling was assessed by linear regression of ARI and AT. Dispersion of repolarization across all 10 sites and between adjacent sites increased with dobutamine compared with control (whole DOR: range 15 +/- 2 vs. 12 +/- 2 ms, P = 0.06 and standard deviation 5.5 +/- 0.9 vs. 4.3 +/- 0.9 ms, P = 0.04; adjacent DOR: 5.9 +/- 0.8 vs. 4.5 +/- 0.6 ms, P = 0.04). This was associated with shallower ARI/AT slopes (-0.3 +/- 0.2 vs. -0.8 +/- 0.2, P = 0.05) and a decrease in ARI-AT correlation (R(2) 0.4 +/- 0.1 vs. 0.6 +/- 0.1, P = 0.05) with dobutamine compared with control.
Conclusion:
Adrenergic stimulation increases apicobasal RV DOR and reduces coupling between activation and repolarization in patients with cardiomyopathy. This may provide a mechanism for the proarrhythmic potential of heightened adrenergic states in these patients.
Related Concept Videos
Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Cardiomyopathy IV: Restrictive Cardiomyopathy
Cardiomyopathy II: Dilated Cardiomyopathy
Heart Failure Drugs: Inhibitors of Renin-Angiotensin System
Mechanism of Cardiac Arrhythmias
