Dizziness and light-headedness both describe feeling faint, feeling unbalanced, vertigo or the sensation of being unsteady. Although dizziness and light-headedness usually occur due to non-serious conditions such as standing up too quickly, flu, common cold or allergies, conditions that affect the flow of blood to the brain may also result in dizziness and light-headedness, according to MedLine Plus and the National Institutes of Health.
Arrhythmia
Electrical impulses within the heart trigger it to beat rhythmically in order to pump approximately 2,000 gallons of blood every day, according to the American Heart Association. A heart that fails to beat rhythmically may feel like a fluttering or racing heart and can lead to chest pain, shortness of breath, light-headedness, dizziness and fainting. Although some arrhythmias may lead to life-threatening conditions, such as ventricular fibrillation, the presence of these symptoms does not necessarily indicate a serious condition, according to MayoClinic.com.
A heart that fails to beat rhythmically may cause a slow heartbeat, known as bradycardia, or a fast heartbeat known as tachycardia. When a heart beats too slow the amount of blood being pumped to the body reduces, leading to dizziness and light-headedness. A heart that beats too fast beats inefficiently allowing blood to remain in the heart which decreases the amount of blood flowing through the body, also leading to dizziness and light-headedness.
Shock
Shock describes a life-threatening condition characterized by a blood pressure too low to sustain life. Shock occurs when a patient loses an excessive volume of blood, when the heart fails to pump or when blood vessels excessively dilate. The sudden drop in blood pressure inhibits blood from reaching cells throughout the body. The resulting death of cells damages organs such as the brain, kidneys, liver and heart.
A patient in shock will feel sleepy, confused, cold and sweaty and appear bluish and pale, as described by the Merck Manual. The lack of blood flow to the brain causes light-headedness and dizziness especially when attempting to sit up. If left untreated, the damage to organs becomes so extensive they begin to fail leading to death.
Heart Attack
A heart attack occurs when the blood flow to the heart becomes blocked, causing cell death and damage in the heart muscle. As the leading cause of death among men and women in the United States, according to the National Heart Lung and Blood Institute, a heart attack requires prompt treatment to prevent permanent damage to the heart.
Symptoms of a heart attack include chest pain, upper body discomfort in the arms, back, neck or jaw and shortness of breath. Because the heart fails to beat normally, a heart attack inhibits blood flow to the body leading to dizziness and light-headedness.
