Cardiovascular disease has been the number one killer in Europe every year since 1900. The cardiovascular system is composed of the heart and blood vessels. Its primary function is to deliver oxygenated blood and nutrients to every cell. Patients experience a variety of symptoms when they have a cardiovascular problem. Coronary artery disease is the most common form of heart disease and the leading cause of death in adults in Europe. Cardiac rhythm disturbances or arrhythmias may arise from a variety of causes— they are not solely caused by AMI. Most cardiac arrest victims have evidence of atherosclerosis or other underlying cardiac disease. However, cardiac arrest can also occur secondary to electrocution, submersion, and other types of trauma. Indeed, many cardiac arrest victims have no warning before the event occurs. A patient who presents with or develops symptomatic bradycardia needs to be treated in a manner that will increase the HR and improve CO. A patient who presents with or develops tachycardia presents a more complicated situation than one in bradycardia. Tachycardia can have a supraventricular pacemaker site or may be ventricular in origin. In addition, the patient may be mildly or severely symptomatic owing to the tachycardia or another condition. Because of the many possible variations in tachycardic patients, several judgements must be made before treatment is begun. Patients with diseases affecting the cardiovascular system may be taking a wide variety of medications for a variety of reasons, and it is not always possible to identify the patient’s specific problem on the basis of a medication that he or she is taking.