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Heart palpitation

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Heart palpitation

Palpitation
ICD-10 9 DiseasesDB MedlinePlus eMedicine emphysema.

Patients can notice palpitations through abnormal or normal awareness. 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. In general, a palpitation can be one of two types of beats: premature atrial contraction, or a premature ventricular contraction.[1] Palpitations may be brought on by overexertion, stress, anxiety, panic,[2] adrenaline, alcohol, nicotine, caffeine, cocaine, amphetamines, and other drugs, disease (such as hyperthyroidism and pheochromocytoma) or as a symptom of panic disorder and many other factors. It can also happen in mitral stenosis.

Palpitations may be associated with heart problems, but also with kidney disease, electrolyte imbalances for magnesium, potassium and calcium, thyroid malfunction, asthma, and deficiencies or lowered stores of certain nutrients which may include, but are not limited to, taurine, arginine, iron (anemias), potassium and magnesium. Nearly everyone experiences an occasional awareness of their heart beating or weak chest, but when it occurs frequently (more than 6 per minute as a rule of thumb), it can indicate a problem.

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, frequent headaches, chest pain or dizziness, indicate irregular or poor heart function and should be investigated by a medical professional. 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.

PVC (a type of palpitation) recording
noicon
An audio clip recording of a PVC symptom, made with a cardiac event monitor.

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PVC recording
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A full 2 minute cardiac event monitor recording with many PVC symptoms around mid-recording.

Problems playing this file? See media help.

Causes

Palpitations can be attributed to one of four main causes:

  1. Extra-cardiac stimulation of the parasympathetic nervous system (inappropriate stimulation of the parasympathetic nervous system, particularly the vagus nerve (which innervates the heart), can be caused by anxiety and stress due to acute or chronic elevations in glucocorticoids and catecholamines. Gastrointestinal distress such as bloating or indigestion, along with muscular imbalances and poor posture, can also irritate the vagus nerve causing palpitations)
  2. Sympathetic overdrive (panic disorders, hypoglycemia, hypoxia, antihistamines (i.e. levocetirizine), anemia, heart failure, mitral valve prolapse).[3]
  3. Hyperdynamic circulation (valvular incompetence, thyrotoxicosis, hypercapnia, pyrexia, anemia, pregnancy).
  4. Cardiac dysrhythmias (ectopic beat, premature atrial contraction, junctional escape beat, premature ventricular contraction, atrial fibrillation, supraventricular tachycardia, ventricular tachycardia, ventricular fibrillation, heart block).

Anxiety and stress

Anxiety and stress elevate the body's level of cortisol and adrenalin, which in turn can interfere with the normal functioning of the parasympathetic nervous system resulting in overstimulation of the vagus nerve.[4] Vagus nerve induced palpitations are felt as a thud, a hollow fluttery sensation, or a skipped beat, depending on at what point during the heart's normal rhythm the vagus nerve fires. In many cases, the anxiety and panic of experiencing palpitations causes a sufferer to experience further anxiety and increased vagus nerve stimulation. The link between anxiety and palpitations may also explain why many panic attacks involve an impending sense of cardiac arrest. Similarly, physical and mental stress may contribute to the occurrence of palpitations, possibly due to the depletion of certain micronutrients involved in maintaining healthy psychological and physiological function.[5] Gastrointestinal bloating, indigestion and hiccups have also been associated with overstimulation of the vagus nerve causing palpitations, due to branches of the vagus nerve innervating the GI tract, diaphragm and lungs.

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 after 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), and whether continual palpitations can be stopped by deep breathing or changing body positions. 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 be present 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 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. An implantable loop recorder 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 ultrasound 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 palpitations will depend on the severity and cause of the condition. Palpitations that are caused by heart muscle defects will require specialist examination and assessment. Palpitations that are caused by vagus nerve stimulation rarely involve physical defects of the heart. Such palpitations are extra-cardiac in nature, that is, palpitations originating from outside the heart itself. Accordingly, vagus nerve induced palpitations are not evidence of an unhealthy heart muscle.

Treatment of vagus nerve induced palpitations will need to address the cause of irritation to the vagus nerve and/or the parasympathetic nervous system generally. It is of significance that anxiety and stress are strongly associated with increased frequency and severity of vagus nerve induced palpitations. Anxiety and stress reduction techniques such as meditation and massage may prove extremely beneficial to reduce or eliminate symptoms temporarily. Supplementation with certain nutrients such as taurine, citrulline (or arginine), GABA, and magnesium may also provide some reduction in nervous tension and anxiety,[6] which in turn can help reduce symptoms. Changing body position (e.g. sitting upright rather than lying down) may also help reduce symptoms due to the vagus nerve's innervation of several structures within the body such as the GI tract, diaphragm and lungs.

With respect to the hyperstimulation of the vagus nerve, anticholinergic agents such anti-histamine or tricyclic antidepressant may inhibit the effect of acetylcholine in activating the vagus nerve thereby reducing its interference on the heart's normal rhythm.

See also

References

External links

  • Medic8 Family Health Guide
  • MedlinePlus Medical Encyclopedia, NIH
  • Arrhythmia (palpitations)
  • Heart Palpitations
  • Irregular heartbeat
  • Abnormal Heart Rhythm (Arrhythmia)
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