Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac musclecontractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart.[1]
Symptoms include a rapid pulsation, an abnormally rapid or irregular beating of the heart.[1] Palpitations are a sensory symptom and are often described as a skipped beat, rapid fluttering in the chest, pounding sensation in the chest or neck, or a flip-flopping in the chest.[1]
Palpitation can be associated with anxiety and does not necessarily indicate a structural or functional abnormality of the heart, but it can be a symptom arising from an objectively rapid or irregular heartbeat. Palpitation can be intermittent and of variable frequency and duration, or continuous. Associated symptoms include dizziness, shortness of breath, sweating, headaches and chest pain.
"flip-flopping" (or "stop and start"), often caused by premature contraction of the atrium or ventricle, with the perceived "stop" from the pause following the contraction, and the "start" from the subsequent forceful contraction
rapid "fluttering in the chest", with regular "fluttering" suggesting supraventricular or ventricular arrhythmias (including sinus tachycardia) and irregular "fluttering" suggesting atrial fibrillation, atrial flutter, or tachycardia with variable block
Palpitation associated with chest pain suggests coronary artery disease, or if the chest pain is relieved by leaning forward, pericardial disease is suspected. Palpitation associated with light-headedness, fainting or near fainting suggest low blood pressure and may signify a life-threatening cardiac dysrhythmia. Palpitation that occurs regularly with exertion suggests a rate-dependent bypass tract or hypertrophic cardiomyopathy. If a benign cause for these concerning symptoms cannot be found at the initial visit, then ambulatory monitoring or prolonged heart monitoring in the hospital might be warranted. Noncardiac symptoms should also be elicited since the palpitations may be caused by a normal heart responding to a metabolic or inflammatory condition. Weight loss suggests hyperthyroidism. Palpitation can be precipitated by vomiting or diarrhea that leads to electrolyte disorders and hypovolemia. Hyperventilation, hand tingling, and nervousness are common when anxiety or panic disorder is the cause of the palpitations.[4]
Causes
The responsibility for the perception of heartbeat by neural pathways is not clear. It has been hypothesized that these pathways include different structures located both at the intra-cardiac and extra-cardiac level.[1] Palpitations are a widely diffuse complaint and particularly in subjects affected by structural heart disease.[1] The list of causes of palpitations is long, and in some cases, the etiology is unable to be determined.[1] In one study reporting the etiology of palpitations, 43% were found to be cardiac, 31% psychiatric, and approximately 10% were classified as miscellaneous (medication induced, thyrotoxicosis, caffeine, cocaine, anemia, amphetamine, mastocytosis).[1]
Pectus Excavatum, also known as funnel chest, is a chest wall deformity. When the breastbone (sternum) and attached ribs are sunken in enough to put excess pressure on the heart and lungs which can cause tachycardia and skipped beats.
Palpitations can occur during times of catecholamine excess, such as during exercise or at times of stress.[1] The cause of the palpitations during these conditions is often a sustained supraventricular tachycardia or ventricular tachyarrhythmia.[1] Supraventricular tachycardias can also be induced at the termination of exercise when the withdrawal of catecholamines is coupled with a surge in the vagal tone.[1] Palpitations secondary to catecholamine excess may also occur during emotionally startling experiences, especially in patients with a long QT syndrome.[1]
Psychiatric problems
Adrenaline, a natural hormone released during periods of emotional and physical stress, can cause palpitations as a result of its effects on the parasympathetic nervous system.
Anxiety and stress elevate the body's level of cortisol and adrenaline, which in turn can interfere with the normal functioning of the parasympathetic nervous system resulting in overstimulation of the vagus nerve. Vagus nerve induced palpitation is 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 cause a patient to experience further anxiety and increased vagus nerve stimulation. The link between anxiety and palpitation 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 palpitation, possibly due to the depletion of certain micronutrients involved in maintaining healthy psychological and physiological function.[6] 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.[citation needed]
The sensation of palpitations can arise from extra-systoles or tachyarrhythmia.[1] It is very rarely noted due to bradycardia.[1] Palpitations can be described in many ways.[1] The most common descriptions include a flip-flopping in the chest, a rapid fluttering in the chest, or pounding in the neck.[1] The description of the symptoms may provide a clue regarding the etiology of the palpitations, and the pathophysiology of each of these descriptions is thought to be different.[1] In patients who describe the palpitations as a brief flip-flopping in the chest, the palpitations are thought to be caused by extra- systoles such as supraventricular or ventricularpremature contractions.[1] The flip-flop sensation is thought to result from the forceful contraction following the pause, and the sensation that the heart is stopped results from the pause.[1] The sensation of rapid fluttering in the chest is thought to result from a sustained ventricular or supraventricular arrhythmia.[1] Furthermore, the sudden cessation of this arrhythmia can suggest paroxysmal supraventricular tachycardia.[1] This is further supported if the patient can stop the palpitations by using Valsalva maneuvers.[1] The rhythm of the palpitations may indicate the etiology of the palpitations (irregular palpitations indicate atrial fibrillation as a source of the palpitations).[1] An irregular pounding sensation in the neck can be caused by the dissociation of mitral valve and tricuspid valve, and the subsequent atria are contracting against a closed tricuspid and mitral valves, thereby producing cannon A waves.[1] Palpitations induced by exercise could be suggestive of cardiomyopathy, ischemia or channelopathies.[1]
Diagnosis
The most important initial clue to the diagnosis is one's description of palpitation. 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.[1]
A complete and detailed history and physical examination are two essential elements of the evaluation of a patient with palpitations.[1] The key components of a detailed history include age of onset, description of the symptoms including rhythm, situations that commonly result in the symptoms, mode of onset (rapid or gradual), duration of symptoms, factors that relieve symptoms (rest, Valsalva), positions and other associated symptoms such as chest pain, lightheadedness or syncope. A patient can tap out the rhythm to help demonstrate if they are not currently experiencing the symptoms. The patient should be questioned regarding all medications, including over-the-counter medications. Social history, including exercise habits, caffeine consumption, alcohol and illicit drug use, should also be determined. Also, past medical history and family history may provide indications to the etiology of the palpitations.[1]
Palpitations that have been a condition since childhood are most likely caused by a supraventricular tachycardia, whereas palpitations that first occur later in life are more likely to be secondary to structural heart disease.[1] A rapid regular rhythm is more likely to be secondary to paroxysmal supraventricular tachycardia or ventricular tachycardia, and a rapid and irregular rhythm is more likely to be an indication of atrial fibrillation, atrial flutter, or tachycardia with variable block.[1] Supraventricular and ventricular tachycardia is thought to result in palpitations with abrupt onset and abrupt termination.[1] In patients who can terminate their palpitations with a Valsalva maneuver, this is thought to indicate possibly a supraventricular tachycardia.[1] Palpitations associated with chest pain may suggest myocardial ischemia.[1] Lastly, when lightheadedness or syncope accompanies the palpitations, ventricular tachycardia, supraventricular tachycardia, or other arrhythmias should be considered.[1]
The diagnosis is usually not made by a routine medical examination and scheduled electrical tracing of the heart's activity (ECG) because most people cannot arrange to have their symptoms be present while visiting the hospital.[1] Nevertheless, findings such as a heart murmur or an abnormality of the ECG might be indicative of probable diagnosis. In particular, ECG changes that are associated with specific disturbances of the heart rhythm may be noticed; thus physical examination and ECG remain important in the assessment of palpitation.[1] Moreover, a complete physical exam should be performed including vital signs (with orthostatic vital signs), cardiac auscultation, lung auscultation, and examination of extremities.[1] A patient can tap out the rhythm to help demonstrate what they felt previously, if they are not currently experiencing the symptoms.[1]
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).[8]
The next level of diagnostic testing is usually 24-hour (or longer) ECG monitoring, using a recorder called a Holter monitor, which can record the ECG continuously during a 24-hour or 48-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. More recent technology such as the Zio Patch allows continuous recording for up to 14 days; the patient indicates when symptoms occur by pushing a button on the device and keeps a log of the events.[9]
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.[citation needed]
Investigation of heart structure can also be important. The heart in most people with palpitation 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.[citation needed]
Evaluation
A 12-lead electrocardiogram must be performed on every patient complaining of palpitations.[1] The presence of a short PR interval and a delta wave (Wolff-Parkinson-White syndrome) is an indication of the existence of ventricular pre-excitation.[1] Significant left ventricular hypertrophy with deep septal Q waves in I, L, and V4 through V6 may indicate hypertrophic obstructive cardiomyopathy.[1] The presence of Q waves may indicate a prior myocardial infarction as the etiology of the palpitations, and a prolonged QT interval may indicate the presence of the long QT syndrome.[1]
Most patients have benign conditions as the etiology for their palpitations.[1] The goal of further evaluation is to identify those patients who are at high risk for an arrhythmia.[1] Recommended laboratory studies include an investigation for anemia, hyperthyroidism and electrolyte abnormalities.[1]Echocardiograms are indicated for patients in whom structural heart disease is a concern.[1]
Further diagnostic testing is recommended for those in whom the initial diagnostic evaluation (history, physical examination, and EKG) suggest an arrhythmia, those who are at high risk for an arrhythmia, and those who remain anxious to have a specific explanation of their symptoms.[1] People considered to be at high risk for an arrhythmia include those with organic heart disease or any myocardial abnormality that may lead to serious arrhythmias.[1] These conditions include a scar from myocardial infarction, idiopathic dilated cardiomyopathy, clinically significant valvular regurgitant, or stenotic lesions and hypertrophic cardiomyopathies.[1]
An aggressive diagnostic approach is recommended for those at high risk and can include ambulatory monitoring or electrophysiologic studies.[1] There are three types of ambulatory EKG monitoring devices: Holter monitor, continuous-loop event recorder, and an implantable loop recorder.[1]
People who are going to have these devices checked should be made aware of the properties of the devices and the accompanying course of the examination for each device.[1] The Holter monitor is a 24-hour monitoring system that is worn by exam takers themselves and records and continuously saves data.[1] Holter monitors are typically worn for a few days.[1] The continuous-loop event recorders are also worn by the exam taker and continuously record data, but the data is saved only when someone manually activates the monitor.[1] The continuous-loop recorders can be long worn for longer periods of time than the Holter monitors and therefore have been proven to be more cost-effective and efficacious than Holter monitors.[1] Also, because the person triggers the device when he/she feel the symptoms, they are more likely to record data during palpitations.[1] An implantable loop recorder is a device that is placed subcutaneously and continuously monitors for cardiac arrhythmias.[1] These are most often used in those with unexplained syncope and can be used for longer periods of time than the continuous loop event recorders. An implantable loop recorder is a device that is placed subcutaneously and continuously monitors for the detection of cardiac arrhythmias.[1] These are most often used in those with unexplained syncope and are a used for longer periods of time than the continuous loop event recorders.[1] Electrophysiology testing enables a detailed analysis of the underlying mechanism of the cardiac arrhythmia as well as the site of origin.[1] EPS studies are usually indicated in those with a high pretest likelihood of a serious arrhythmia.[1] The level of evidence for evaluation techniques is based upon consensus expert opinion.[1]
Treatment
Non-medical treatments
The patient should avoid receiving any external effect that causes palpitations. Anxiety and stress reduction techniques, such as meditation and massage, may prove extremely beneficial to reduce or eliminate symptoms temporarily.
If the palpitations consist of a simple acceleration of the heart beats, and the heart and general patient's health remain stable enough, it is possible[10] to correct the palpitations by a simple deceleration using some physical maneuvers called vagal maneuvers. 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.[citation needed]
Anyway, if the cause of palpitations is a chronic problem, they would return after some time, unless the problem that causes them is corrected.
Medical treatments
Treating palpitation will depend on the severity and cause of the condition.[1]
Radiofrequency ablation can cure most types of supraventricular and many types of ventricular tachycardias.[1] While catheter ablation is currently a common treatment approach, there have been advances in stereotactic radioablation for certain arrhythmias.[1] This technique is commonly used for solid tumors and has been applied with success in management of difficult to treat Ventricular Tachycardia and Atrial Fibrillation.[1]
The most challenging cases involve palpitations that are secondary to supraventricular or ventricular ectopy or associated with normal sinus rhythm.[1] These conditions are thought to be benign, and the management involves reassurance of the patient that these arrhythmias are not life-threatening.[1] In these situations when the symptoms are unbearable or incapacitating, treatment with beta-blocking medications could be considered, and may provide a protective effect for otherwise healthy individuals.[1]
People who present to the emergency department who are asymptomatic, with unremarkable physical exams, have non-diagnostic EKGs and normal laboratory studies, can safely be sent home and instructed to follow up with their primary care provider or cardiologist.[1] Patients whose palpitations are associated with syncope, uncontrolled arrhythmias, hemodynamic compromise, or angina should be admitted for further evaluation.[1]
Palpitation that is caused by heart muscle defects will require specialist examination and assessment.
Palpitation that is caused by a stimulation of the vagus nerve rarely involves physical defects of the heart. Such palpitations are extra-cardiac in nature, that is, palpitation originating from outside the heart itself. Accordingly, vagus nerve induced palpitation is not evidence of an unhealthy heart muscle.[citation needed] Treatment of vagus nerve induced palpitation will need to address the cause of irritation to the vagus nerve 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 palpitation.
Prognosis
Direct-to-consumer options for monitoring heart rate and heart rate variability have become increasingly prevalent using smartphones and smartwatches.[1] These monitoring systems have become increasingly validated and may help provide early identification for those at risk for a serious arrhythmia such as atrial fibrillation.[1]
Palpitations can be a very concerning symptom for people.[1] The etiology of the palpitations in most patients is benign.[1] Therefore, comprehensive workups are not indicated.[1] However, appropriate follow up with the primary care provider can provide the ability to monitor symptoms over time and determine if consultation with a cardiologist is required.[1] People who are determined to be at high risk for palpitations of serious or life-threatening etiologies require a more extensive workup and comprehensive management.[1]
Once a cause is determined, the recommendations for treatment are quite strong, with moderate to high quality therapies studied.[1] Partnership with the people who have the chief complaint of palpitation, using a shared decision-making model and involving an interprofessional team including a nurse, nurse practitioner, physician assistant, and physician can help best direct therapy and provide good followup.[1]
Prevalence
Palpitations are a common complaint in the general population, particularly in those affected by structural heart disease.[1] Clinical presentation is divided into four groups: extra-systolic, tachycardic, anxiety-related, and intense.[1]Anxiety-related is the most common.[1]
Cardioversion is a medical procedure by which an abnormally fast heart rate (tachycardia) or other cardiac arrhythmia is converted to a normal rhythm using electricity or drugs.
Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal or abnormal.
A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node. PVCs may cause no symptoms or may be perceived as a "skipped beat" or felt as palpitations in the chest. PVCs do not usually pose any danger.
Wolff–Parkinson–White syndrome (WPWS) is a disorder due to a specific type of problem with the electrical system of the heart involving an accessory pathway able to conduct electrical current between the atria and the ventricles, thus bypassing the atrioventricular node. About 60% of people with the electrical problem developed symptoms, which may include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope. Rarely, cardiac arrest may occur. The most common type of irregular heartbeat that occurs is known as paroxysmal supraventricular tachycardia.
Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms (arrhythmias) usually caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a variant of sick sinus syndrome in which the arrhythmia alternates between fast and slow heart rates.
Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia. Atrial flutter is characterized by a sudden-onset (usually) regular abnormal heart rhythm on an electrocardiogram (ECG) in which the heart rate is fast. Symptoms may include a feeling of the heart beating too fast, too hard, or skipping beats, chest discomfort, difficulty breathing, a feeling as if one's stomach has dropped, a feeling of being light-headed, or loss of consciousness.
Short QT syndrome (SQT) is a very rare genetic disease of the electrical system of the heart, and is associated with an increased risk of abnormal heart rhythms and sudden cardiac death. The syndrome gets its name from a characteristic feature seen on an electrocardiogram (ECG) – a shortening of the QT interval. It is caused by mutations in genes encoding ion channels that shorten the cardiac action potential, and appears to be inherited in an autosomal dominant pattern. The condition is diagnosed using a 12-lead ECG. Short QT syndrome can be treated using an implantable cardioverter-defibrillator or medications including quinidine. Short QT syndrome was first described in 2000, and the first genetic mutation associated with the condition was identified in 2004.
Ventricular tachycardia is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short period of time are referred to as an electrical storm. Short periods may occur without symptoms, or present with lightheadedness, palpitations, shortness of breath, chest pain, and decreased level of consciousness. Ventricular tachycardia may lead to coma and persistent vegetative state due to lack of blood and oxygen to the brain. Ventricular tachycardia may result in ventricular fibrillation (VF) and turn into cardiac arrest. This conversion of the VT into VF is called the degeneration of the VT. It is found initially in about 7% of people in cardiac arrest.
Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. This is in contrast to the other group of fast heart rhythms – ventricular tachycardia, which start within the lower chambers of the heart. There are four main types of SVT: atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and Wolff–Parkinson–White syndrome. The symptoms of SVT include palpitations, feeling of faintness, sweating, shortness of breath, and/or chest pain.
AV-nodal reentrant tachycardia (AVNRT) is a type of abnormal fast heart rhythm. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men. The main symptom is palpitations. Treatment may be with specific physical maneuvers, medications, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.
Catheter ablation is a procedure that uses radio-frequency energy or other sources to terminate or modify a faulty electrical pathway from sections of the heart of those who are prone to developing cardiac arrhythmias such as atrial fibrillation, atrial flutter and Wolff-Parkinson-White syndrome. If not controlled, such arrhythmias increase the risk of ventricular fibrillation and sudden cardiac arrest. The ablation procedure can be classified by energy source: radiofrequency ablation and cryoablation.
Premature atrial contraction (PAC), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common arrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat, in contrast to escape beats, in which the normal sinoatrial node fails, leaving a non-nodal pacemaker to initiate a late beat.
Tachycardia-induced cardiomyopathy (TIC) is a disease where prolonged tachycardia or arrhythmia causes an impairment of the myocardium, which can result in heart failure. People with TIC may have symptoms associated with heart failure and/or symptoms related to the tachycardia or arrhythmia. Though atrial fibrillation is the most common cause of TIC, several tachycardias and arrhythmias have been associated with the disease.
Clinical cardiac electrophysiology, is a branch of the medical specialty of cardiology concerned with the study and treatment of rhythm disorders of the heart. Cardiologists with expertise in this area are usually referred to as electrophysiologists. Electrophysiologists are trained in the mechanism, function, and performance of the electrical activities of the heart. Electrophysiologists work closely with other cardiologists and cardiac surgeons to assist or guide therapy for heart rhythm disturbances (arrhythmias). They are trained to perform interventional and surgical procedures to treat cardiac arrhythmia.
Wandering atrial pacemaker (WAP) is an atrial rhythm where the pacemaking activity of the heart originates from different locations within the atria. This is different from normal pacemaking activity, where the sinoatrial node is responsible for each heartbeat and keeps a steady rate and rhythm. Causes of wandering atrial pacemaker are unclear, but there may be factors leading to its development. It is often seen in the young, the old, and in athletes, and rarely causes symptoms or requires treatment. Diagnosis of wandering atrial pacemaker is made by an ECG.
Roemheld syndrome (RS), or gastrocardiac syndrome, or gastric cardiac syndrome or Roemheld–Techlenburg–Ceconi syndrome or gastric-cardia, was a medical syndrome first coined by Ludwig von Roemheld (1871–1938) describing a cluster of cardiovascular symptoms stimulated by gastrointestinal changes. Although it is currently considered an obsolete medical diagnosis, recent studies have described similar clinical presentations and highlighted potential underlying mechanisms.
Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. Some types of arrhythmias have no symptoms. Symptoms, when present, may include palpitations or feeling a pause between heartbeats. In more serious cases, there may be lightheadedness, passing out, shortness of breath, chest pain, or decreased level of consciousness. While most cases of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.
Celivarone is an experimental drug being tested for use in pharmacological antiarrhythmic therapy. Cardiac arrhythmia is any abnormality in the electrical activity of the heart. Arrhythmias range from mild to severe, sometimes causing symptoms like palpitations, dizziness, fainting, and even death. They can manifest as slow (bradycardia) or fast (tachycardia) heart rate, and may have a regular or irregular rhythm.
An implantable loop recorder (ILR), also known as an insertable cardiac monitor (ICM), is a small device that is implanted under the skin of the chest for cardiac monitoring, to record the heart's electrical activity for an extended period.
An automatic tachycardia is a cardiac arrhythmia which involves an area of the heart generating an abnormally fast rhythm, sometimes also called enhanced automaticity. These tachycardias, or fast heart rhythms, differ from reentrant tachycardias in which there is an abnormal electrical pathway which gives rise to the pathology. Most automatic tachycardias are supraventricular tachycardias (SVT). It is important to recognize an automatic tachycardia because the treatment will be different to that for a reentrant tachycardia. The most useful clue will be the presence of 'warm up' and 'cool down'. This means that whereas a reentrant tachycardia will both begin and end abruptly as cardiac conduction uses then ceases to use the accessory pathway, an automatic tachycardia will rise and fall gradually in rate as the automatic focus increases and decreases its automatic rate of electrical discharge.
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