“…Atrioventricular synchrony provides normal cardiac output with preservation of the atrial contribution to ventricular filling; this is a more physiologic response to sinus node rate and allows a more appropriate response during exercise or sympathetic stimulation and a potentially longer battery life, as well as avoidance of increased atrial pressures that can lead to derangements in neurohormones such as atrial natriuretic peptides. 6 In human studies, DDD-paced patients have less sleep disturbance and sleep apnea, 7 improved cardiac output and systolic blood pressure, 8 and lower atrial and pulmonary capillary wedge pressures and plasma atrial natriuretic peptide concentrations, compared with VVI-or VVIR-paced patients. 6 The disadvantages of DDD pacemakers include size limitations among recipients; these are generally reserved for use in larger dogs.…”