Palpitation

Palpitation

ICD-10	R00.2
ICD-9	785.1
DiseasesDB	29231
MedlinePlus	003081
eMedicine	aaem/337

A palpitation is an abnormality of heartbeat that causes a conscious awareness of its beating, whether it is too slow, too fast, irregular, or at its normal frequency. The word may also refer to this sensation itself. It can be caused by (but should not be confused with) ectopic beat, which is a more specific diagnosis.

The difference between an abnormal awareness and a normal awareness is that the former interrupts other thoughts, whereas the latter is almost always caused by a concentration on the beating of one's heart. Palpitations may be brought on by overexertion, adrenaline, alcohol, nicotine, caffeine, cocaine, amphetamines, and other drugs, disease (such as hyperthyroidism and pheochromocytoma) or as a symptom of panic disorder. More colloquially, it can also refer to a shaking motion. It can also happen in mitral stenosis.

Nearly everyone experiences an occasional awareness of their heart beating, but when it occurs frequently, it can indicate a problem. Palpitations may be associated with heart problems, but also with anemias and thyroid malfunction.

Attacks can last for a few seconds or hours, and may occur very infrequently, or more than daily. Palpitations alongside other symptoms, including sweating, faintness, chest pain or dizziness, indicate irregular or poor heart function and should be investigated.

Palpitations may also be associated with anxiety and panic attacks, in which case psychological assessment is recommended. This is a common disorder associated with many common medications such as anti-depressants.

Palpitations can also occur from blood loss, excessive pain, or lack of oxygen.

Causes

Palpitations can be attributed to one of three main causes:

1. Hyperdynamic circulation (valvular incompetence, thyrotoxicosis, hypercapnia, pyrexia, anemia, pregnancy).
2. Sympathetic overdrive (panic disorders, hypoglycemia, hypoxia, levocetirizine antihistamines, anemia, heart failure, mitral valve prolapse).
3. Cardiac dysrhythmias (premature atrial contraction, junctional escape beat, premature ventricular contraction, atrial fibrillation, supraventricular tachycardia, ventricular tachycardia, ventricular fibrillation, heart block).

Symptoms

Many times, the person experiencing palpitations may not be aware of anything apart from the abnormal heart rhythm itself. But palpitations can be associated with other things such as tightness in the chest, shortness of breath, dizziness or light-headedness. Depending on the type of rhythm problem, these symptoms may be just momentary or more prolonged. Actual blackouts or near blackouts, associated with palpitations, should be taken seriously because they often indicate the presence of important underlying heart disease. Another symptom is pain in arms or legs sometimes lasting through the night before the palpitation.

Diagnosis

The most important initial clue to the diagnosis is one's description of the palpitations. The approximate age of the person when first noticed and the circumstances under which they occur are important, as is information about caffeine intake (tea or coffee drinking). It is also very helpful to know how they start and stop (abruptly or not), whether or not they are regular, and approximately how fast the pulse rate is during an attack. If the person has discovered a way of stopping the palpitations, that is also helpful information.

The diagnosis is usually not made by a routine medical examination and electrical tracing of the heart's activity (ECG), because most people cannot arrange to have their symptoms while visiting the doctor. Nevertheless, findings such as a heart murmur or an abnormality of the ECG, which could point to the probable diagnosis, may be discovered. In particular, ECG changes that can be associated with specific disturbances of the heart rhythm may be picked up; so routine physical examination and ECG remain important in the assessment of palpitations.

Blood tests, particularly tests of thyroid gland function are also important baseline investigations (an overactive thyroid gland is a potential cause for palpitations; the treatment in that case is to treat the thyroid gland over-activity).

The next level of diagnostic testing is usually 24 hour (or longer) ECG monitoring, using a form of tape recorder (a bit like a Walkman) called a Holter monitor, which can record the ECG continuously during a 24-hour period. If symptoms occur during monitoring it is a simple matter to examine the ECG recording and see what the cardiac rhythm was at the time. For this type of monitoring to be helpful, the symptoms must be occurring at least once a day. If they are less frequent, the chances of detecting anything with continuous 24, or even 48-hour monitoring, are substantially lowered.

Other forms of monitoring are available, and these can be useful when symptoms are infrequent. A continuous-loop event recorder monitors the ECG continuously, but only saves the data when the wearer activates it. Once activated, it will save the ECG data for a period of time before the activation and for a period of time afterwards - the cardiologist who is investigating the palpitations can program the length of these periods. A new type of continuous-loop recorder has been developed recently that may be helpful in people with very infrequent, but disabling symptoms. This recorder is implanted under the skin on the front of the chest, like a pacemaker. It can be programmed and the data examined using an external device that communicates with it by means of a radio signal.

Investigation of heart structure can also be important. The heart in most people with palpitations is completely normal in its physical structure, but occasionally abnormalities such as valve problems may be present. Usually, but not always, the cardiologist will be able to detect a murmur in such cases, and an echo scan of the heart (echocardiogram) will often be performed to document the heart's structure. This is a painless test performed using sound waves and is virtually identical to the scanning done in pregnancy to look at the fetus.

External links

• Medic8 Family Health Guide
• MedlinePlus Medical Encyclopedia, NIH

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