A palpitation is an abnormal awareness of the beating of the heart,[1] whether it is too slow, too fast, irregular, or at its normal frequency. It can be caused by (but should not be confused with) ectopic beat, which is a more specific diagnosis. It is also the associated characteristic of angina.
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, 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 of palpitation
Palpitations can be attributed to one of three main causes:
- Hyperdynamic circulation (Valvular Incompetence, Thyrotoxicosis, Hypercapnia, Pyrexia, Anemia, Pregnancy)
- Sympathetic overdrive (Panic disorders, Hypoglycemia, Hypoxia, Levocetirizine antihistamines, Anemia, Heart Failure, Mitral valve prolapse.[2])
- Arrhythmias (Premature atrial contraction, Junctional escape beat, Premature ventricular contraction, Atrial fibrillation, Supraventricular tachycardia, Ventricular tachycardia, Ventricular fibrillation, Heart block)
Types
Palpitations may be associated with feelings of anxiety or panic. It is normal to feel the heart thumping when feeling terrified or scared, but it may be difficult to know whether the palpitations or the panicked feeling came first. Unfortunately, since it can take some time before a clear diagnosis is made in a patient complaining of palpitations, people are sometimes told initially that the problem is anxiety.
Stressful situations cause an increase in the level of stress hormones, such as adrenaline, circulating in the blood, and there are some types of abnormal heart rhythm that can be stimulated by adrenaline excess, or by exercise. It may be possible to diagnose these sorts of palpitations by performing simple tests, such as an exercise test, while monitoring the ECG.
Some types of abnormal heart rhythm seem to be affected by posture. For many people, standing up straight after bending over can provoke a rapid heart rate. Often these attacks can be abolished again by lying down. Many people, if not all, are more aware of the heartbeat when lying quietly in bed at night. This is partly because at that time, the attention is not focused on other things, but also because the slower heart beat at rest can allow more premature beats to occur.
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.
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 then the chances of detecting anything with continuous 24, or even 48-hour monitoring, are quite remote.
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.
Treatment
Treating heart palpitations depends greatly on the nature of the problem. In many patients, caffeine intake triggers heart palpitations. In this case, treatment simply requires caffeine intake reduction. If it's been determined that caffeine is not the cause, another dietary consideration is too little magnesium, particularly in pre-menopausal women. A supplement of equal dosages of magnesium and calcium may be helpful in eliminating palpitations. For severe cases, medication is often prescribed.
A variety of medications manipulate heart rhythm, which can be used to try to prevent palpitations. If severe palpitations occur, a beta-blocking drug is commonly prescribed. These block the effect of adrenaline on the heart, and are also used for the treatment of angina and high blood pressure. However, they can cause drowsiness, sleep disturbance, depression, impotence, and can aggravate asthma. Other anti-arrhythmic drugs can be employed if beta-blockers are not appropriate.
If heart palpitations become severe, antiarrhythmic medication can be injected intravenously. If this treatment fails, cardioversion may be required. Cardioversion is usually performed under a short general anaesthesia, and involves delivering an electric shock to the chest, which stops the abnormal rhythm and allows the normal rhythm to continue.
For some patients, often those with specific underlying problems found in ECG tests, an electrophysiological study may be advised. This procedure involves inserting a series of wires into a vein in the groin, or the side of the neck, and positioning them inside the heart. Once in position, the wires can be used to record the ECG from different sites within the heart, and can also start and stop abnormal rhythms to further accurate diagnosis. If appropriate, i.e. if an electrical "short circuit" is shown to be responsible for the abnormal rhythm, then a special wire can be used to cut the "short circuit" by placing a small burn at the site. This is known as "radiofrequency ablation" and is curative in the majority of patients with this condition.
Atrial fibrillation has been discussed in a separate article. Treatment may include medication to control heart rate, or cardioversion to support normal heart rhythm. Patients may require medication after a cardioversion to maintain a normal rhythm. In some patients, if attacks of atrial fibrillation occur frequently despite medication, ablation of the connection between the atria and the ventricles (with implantation of a pacemaker) may be advised. A very important risk of atrial fibrillation is the increased risk of stroke. Management of atrial fibrillation usually includes some form of blood thinning treatment.
Generally speaking, serious arrhythmias occur in patients who are known to have heart disease, or carry a genetic predisposition for heart disease or related abnormalities and complications.
Palpitations, in the setting of the above problems, or occurrences such as blackouts or near blackouts, should be taken seriously. Even if ultimately nothing is found, a doctor should be contacted immediately to arrange the appropriate investigations, especially if palpitations occur with blackouts or if any of the above conditions are noticed.
References
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| http://en.wikipedia.org/wiki/Heart_palpitation | |
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