A sudden awareness of the heart beating abnormally is a heart palpitation. An unusually fast heart rhythm often triggers heart palpitations. Many factors and conditions can cause fast heart palpitations, including medications, metabolic imbalances and heart or systemic disorders. Infrequent episodes of heart palpitations often prove harmless. Recurrent or persistent palpitations may indicate a serious medical condition, requiring urgent treatment.
Strenuous Exercise
Exercise causes a natural increase in heart rate, which generally occurs without conscious awareness. In some people, however, strenuous exercise may provoke heart palpitations, according to the Mayo Clinic. A rapid but regular heart rhythm usually represents a normal response to exercise-induced increased workload on the heart. Rapid, irregular heart rhythms during or immediately after exercise may indicate an abnormality of the heart's conduction system, especially if accompanied by shortness of breath, lightheadedness or fainting.
Intense Emotion
Intense emotions such as sudden fear, anxiety or extreme stress often provoke a burst of adrenalin, the "fight or flight" hormone. Adrenalin causes increased heart rate and forceful heart muscle contractions, which may provoke a rapid, pounding heart palpitation, according to Medline Plus.
Caffeine, Nicotine and Alcohol
Caffeine, nicotine and alcohol can trigger increased heart rate, which may provoke episodes of heart palpitations, according to the National Heart, Lung and Blood Institute. Large quantities of caffeine consumed in "energy" drinks may be particularly troublesome, especially when ingested with alcohol in the system.
Drugs
Certain prescription and illicit drugs can increase heart rate and may provoke heart palpitations, according to the Cleveland Clinic. Prescription and over-the-counter medications that may cause fast heart palpitations include certain types of inhaled asthma medicines; thyroid replacement hormones; some types of decongestants and cold medicines; stimulant medications such as methylphenidate and dextroamphetamine; theophylline; digitalis; phenothiazines; ephedra; and certain nutritional and herbal supplements. Street drugs that increase heart rate and may cause palpitations include marijuana and hashish; cocaine and methamphetamine; phencyclidine, or PCP; lysergic acid diethylamide, or LSD; and methylenedioxy-methamphetamine, also known as MDMA or ecstasy.
Medical Conditions
Heart palpitations may be a symptom of certain medical conditions, says Dr. Allan Abbott in a 2005 review article published in American Family Physician. An overactive thyroid gland, or hyperthyroidism, frequently causes an increased, pounding heart rate. Low blood sugar, or hypoglycemia, also commonly provokes a rapid heart rate and palpitations. High fever, dehydration and certain electrolyte imbalances cause increased heart rate, which may be accompanied by palpitations. Pheochromocytoma, an adrenalin-producing tumor of the adrenal gland, characteristically causes a rapid, pounding heart rate. Palpitations are a common symptom of this tumor.
Heart Disorders
A variety of heart disorders can provoke fast palpitations, according to the National Heart, Lung and Blood Institute. Possible heart-related causes of rapid palpitations include heart attack, heart valve disorders, cardiomyopathies, heart failure and abnormalities of the heart's pacing system.
