Cardiac pacemaker controls the rate of contraction for the entire heart muscle because its cells have the quickest rate of spontaneous depolarization, thus they initiate action potentials the quickest. The action potential generated by the SA node passes down the electrical conduction system of the heart, and depolarizes the other potential pacemaker cells (AV node) to initiate action potentials before these other cells have had a chance to generate their own spontaneous action potential, thus they contract and propagate electrical impulses to the pace set by the cells of the SA node. This is the normal conduction of electrical activity in the
Milrinone of the cardiomyocytes therefore increasing the rate at which cells can depolarize and generate contraction. PKA also phosphorylates components on myofilaments allowing actin and myosin to interact more easily and thus increasing contractility and the inotropic state of the heart. Milrinone allows stimulation of cardiac function independently of β-adrenergic receptors which appear to be down-regulated in those with heart failure. In recent years many studies have been performed showing that milrinone use may present potential adverse side effects in heart failure patients. Milrinone Milrinone, commonly known and marketed under the brand name Primacor, is a medication used in patients who