Altered vagal and sympathetic control of heart rate in left ventricular dysfunction and heart failure

Analysis of changes in autonomic control of heart rate in conscious dogs with left ventricular (LV) dysfunction and heart failure (HF) due to rapid pacing shows that heart rate is minimally affected by vagal and sympathetic control in these dogs. The contribution of vagal control of heart rate and control vagal outflow is minimal during the early developmental stage of LV dysfunction. Low levels of atropine vagomimetically affects heart rate in HF and the effects are observed after beta-blockade.f