Palpitations are are often harmless, but in some cases, may even be due to a life-threatening condition.
(1) Cardiac arrhythmias: Cardiac arrhythmias are abnormalities in the rate and / or rhythm of heartbeats, which manifest as palpitations. An arrhythmia should be suspected in a patient with a known heart problem with palpitations occurring during sleep. The palpitations may be associated with lightheadedness and fainting episodes
Some cardiac arrhythmias that can result in palpitations are sinus bradycardia (where the heart rate is slower than normal), supraventricular and ventricular tachycardia (where the heart beats faster than normal), atrial fibrillation (where the upper chamber of the heart beats faster than normal), extrasystoles (where there are isolated extra beats) and heart block (where the impulses are not transmitted through the heart).
(2) Structural cardiac abnormalities: Structural abnormalities of the heart can cause palpitations due to alterations in blood flow through the heart chambers. These abnormalities include defects in the heart valves or in the septa (the partitions between the heart chambers). They may be present since birth or may appear later in life.
(3) Cardiac ischemia: Decreased blood supply to the heart muscles due to a block in the coronary arteries can precipitate an arrhythmia and result in palpitations. The patient has chest pain associated with the palpitations.
(4) Pericarditis: Inflammation of the pericardium or the covering of the heart is called pericarditis. Palpitation is accompanied by chest pain, which is relieved by bending forward.
(1) High output states: High output states are conditions where the heart has to beat faster. These conditions result in an alteration in heart rate and sometimes rhythm leading to palpitations. They include anemia, beriberi (deficiency of vitamin B1) and arterio-venous fistula. Excess thyroid hormone levels can cause the heart to beat faster and result in palpitations. The patient may have additional tremors, loss of hair and weight loss. Fever also increases the metabolic rate of the body and consequently the heart rate and results in palpitations.
(2) Hormonal changes: Hormonal changes during pregnancy can result in palpitations. Besides, palpitations may be more common before, during and after menopause.
(3) Dehydration: Dehydration due to conditions like prolonged vomiting or diarrhea cause abnormalities in electrolyte levels like potassium, magnesium, and calcium in the blood. These can affect the heart resulting in palpitations.
(4) Drugs: Prescription as well as over-the-counter medications can cause palpitations. These include pseudoephedrine, nitrates, overdose of digoxin or insulin, and asthma medications like albuterol inhalers or theophylline. Ephedra containing herbal medications and supplements can also cause palpitations and are banned by the US FDA. Thus, it is necessary to enquire into the medication history of a person who complains of palpitations. Illicit drugs like cocaine and marijuana can also cause palpitations. Their use may be considered in a person complaining of palpitations.
(5) Tea, coffee, tobacco and alcohol: Excessive intake of tea, coffee or alcohol, or cigarette smoking can cause symptoms of palpitations.
(6) Pheochromocytoma: Pheochromocytoma is a tumor of the adrenal gland, which secretes adrenaline. Excessive adrenaline in the blood makes the heart beat faster and results in arrhythmias.
(7) Hypoglycemia: Hypoglycemia or low blood sugar levels result in a faster heart beat. Thus, hypoglycemia should be ruled out in a patient complaining of palpitations especially if the patient is a diabetic.
(8) Physiological causes: Physiological conditions like exercise, stress, emotional and sexual excitement can cause palpitation. These are usually temporary and subside when the person is relaxed.
(9) Psychological / Psychiatric causes: Anxiety and panic disorders can lead to palpitations. Panic disorders are brief periods of overwhelming panic or terror that last for seconds or minutes and are accompanied by palpitations, shortness of breath and dizziness. The patient may give a history of previous panic attack. Palpitations in these conditions are a result in an increased release of substances like adrenaline in the body.