Clinical meaning
The cardiovascular system consists of the heart -- a four-chambered muscular pump -- and the vascular network of arteries, veins, and capillaries that delivers oxygenated blood, nutrients, hormones, and immune cells to every tissue in the body while removing metabolic waste products. The heart's conduction system (SA node, AV node, bundle of His, bundle branches, Purkinje fibers) generates and coordinates electrical impulses that produce the rhythmic contractions of the cardiac cycle. The cardiac cycle consists of systole (ventricular contraction, ejecting blood into the pulmonary artery and aorta) and diastole (ventricular relaxation, allowing filling from the atria). Cardiac output (CO = stroke volume x heart rate, normally 4-8 L/min) is the volume of blood pumped per minute and is the primary determinant of tissue perfusion. Cardiovascular disease -- including hypertension, coronary artery disease, heart failure, and peripheral vascular disease -- remains the leading cause of death worldwide. The practical nurse must understand normal cardiovascular anatomy and physiology, perform accurate cardiovascular assessment (vital signs, heart sounds, peripheral pulses, edema assessment), administer cardiac medications safely, and recognize signs of cardiovascular compromise requiring escalation.