Three common descriptions of "palpitation" are "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; and "pounding in the neck" or neck pulsations, often due to "cannon" A waves in the jugular venous pulsations that occur when the right atrium contracts against a closed tricuspid valve.

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 abnormal heart rhythm. 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.

Palpitations are the perceived abnormality of the heartbeat characterized by awareness of cardiac muscle contractions in the chest: hard, fast and/or irregular beats. It is both a symptom reported by the patient and a medical diagnosis. 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.

Palpitation may be associated with coronary heart disease, hyperthyroidism, diseases affecting cardiac muscle such as hypertrophic cardiomyopathy, diseases causing low blood oxygen such as asthma and emphysema; previous chest surgery; kidney disease; low levels of brain serotonin; blood loss, and pain; drugs such as antidepressants, statins, alcohol, nicotine, caffeine, cocaine, and amphetamines; electrolyte imbalances of magnesium, potassium and calcium; and deficiencies of nutrients such as taurine, arginine, and iron.

Symptoms may include palpitations, feeling faint, sweating, shortness of breath, and chest pain. Episodes start and end suddenly.

Symptoms reported by patients vary in frequency and severity.

Symptoms associated with IST include:

- Frequent or sustained palpitations

- Dyspnea (shortness of breath) and palpitations on exertion

- Pre-syncope (feeling as if about to faint)

- Fatigue (physical)

- Dizziness

- Exercise intolerance

- Occasional paresthesia and cramping

- Symptoms associated with autonomic nervous system disturbance, including GI disturbance

A slow rhythm (less than 60 beats/min), is labelled bradycardia. This may be caused by a slowed signal from the sinus node (sinus bradycardia), a pause in the normal activity of the sinus node (sinus arrest), or by blocking of the electrical impulse on its way from the atria to the ventricles (AV block or heart block). Heart block comes in varying degrees and severity. It may be caused by reversible poisoning of the AV node (with drugs that impair conduction) or by irreversible damage to the node. Bradycardias may also be present in the normally functioning heart of endurance athletes or other well-conditioned persons. Bradycardia may also occur in some types of seizures.

Paroxysmal supraventricular tachycardia (PSVT) is a type of supraventricular tachycardia. Often people have no symptoms. Otherwise symptoms may include palpitations, feeling lightheaded, sweating, shortness of breath, and chest pain. Episodes start and end suddenly.

The cause is not known. Risk factors include alcohol, caffeine, nicotine, psychological stress, and Wolff-Parkinson-White syndrome which often is inherited from a person's parents. The underlying mechanism typically involves an accessory pathway that results in re-entry. Diagnosis is typically by an electrocardiogram (ECG) which shows narrow QRS complexes and a fast heart rhythm typically between 150 and 240 beats per minute.

Vagal maneuvers, such as the valsalva maneuver, are often used as the initial treatment. If not effective and the person has a normal blood pressure the medication adenosine may be tried. If adenosine is not effective a calcium channel blockers or beta blocker may be used. Otherwise synchronized cardioversion is the treatment. Future episodes can be prevented by catheter ablation.

About 2.3 per 1000 people have paroxysmal supraventricular tachycardia. Problems typically begin in those 12 to 45 years old. Women are more often affected than men. Outcomes in those who otherwise have a normal heart are generally good. An ultrasound of the heart may be done to rule out underlying heart problems.

Symptoms can be as follows. They are periodic, and occur only during an "episode", usually after eating.

- Sinus bradycardia

- Difficulty inhaling

- Angina pectoris

- Left ventricular discomfort

- Fatigue

- Anxiety

- Uncomfortable breathing

- Poor perfusion

- Muscle pain (crampiness)

- Burst or sustained vertigo or dizziness

- Sleep disturbance (particularly when sleeping within a few hours of eating, or lying on the left side)

- Extrasystoles

- Hot flashes

Each heart beat originates as an electrical impulse from a small area of tissue in the right atrium of the heart called the sinus node or Sino-atrial node or SA node. The impulse initially causes both atria to contract, then activates the atrioventricular (or AV) node, which is normally the only electrical connection between the atria and the ventricles (main pumping chambers). The impulse then spreads through both ventricles via the Bundle of His and the Purkinje fibres causing a synchronised contraction of the heart muscle and, thus, the pulse.

In adults the normal resting heart rate ranges from 60 to 90 beats per minute. The resting heart rate in children is much faster. In athletes, however, the resting heart rate can be as slow as 40 beats per minute, and be considered as normal.

The term sinus arrhythmia refers to a normal phenomenon of alternating mild acceleration and slowing of the heart rate that occurs with breathing in and out. It is usually quite pronounced in children and steadily decreases with age. This can also be present during meditation breathing exercises that involve deep inhaling and breath holding patterns.

Orthostatic hypotension is characterised by symptoms that occur after standing (from lying or sitting), particularly when this is done rapidly. Many report lightheadedness (a feeling that one might be about to faint), sometimes severe. Generalized weakness or tiredness may also occur. Some also report difficulty concentrating, blurred vision, tremulousness, vertigo, anxiety, palpitations (awareness of the heartbeat), feeling sweaty or clammy, and sometimes nausea. A person may look pale.

Inappropriate Sinus Tachycardia (IST) is a rare type of cardiac arrhythmia, within the category of supraventricular tachycardia (SVT). IST may be caused by the sinus node itself having an abnormal structure or function, or it may be part of a problem called dysautonomia, a disturbance and/or failure of the autonomic nervous system. Research into the mechanism and etiology (cause) of Inappropriate Sinus Tachycardia is ongoing.

IST is viewed by most to be a benign condition in the long-term. Symptoms of IST however, may be distracting and warrant treatment. The heart is a strong muscle and typically can sustain the higher-than-normal heart rhythm, though monitoring the condition is generally recommended.

The mechanism and primary etiology of Inappropriate Sinus Tachycardia has not been fully elucidated. An autoimmune mechanism has been suggested as several studies have detected autoantibodies that activate beta adrenoreceptors in a portion of patients. The mechanism of the arrhythmia primarily involves the sinus node and peri-nodal tissue and does not require the AV node for maintenance. Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully.

Even though many types of sick sinus syndrome produce no symptoms, a person may present with one or more of the following signs and symptoms:

- Stokes-Adams attacks – fainting due to asystole or ventricular fibrillation

- Dizziness or light-headedness

- Palpitations

- Chest pain or angina

- Shortness of breath

- Fatigue

- Headache

- Nausea

While a few seconds may not result in problems longer periods are dangerous. Short periods may occur without symptoms or present with lightheadedness, palpitations, or chest pain. Ventricular tachycardia may result in cardiac arrest and turn into ventricular fibrillation.

Presentation is similar to other forms of rapid heart rate and may be asymptomatic. Palpitations and chest discomfort are common complaints. The rapid uncoordinated heart rate may result in reduced cardiac output, with the heart being unable to provide adequate blood flow and therefore oxygen delivery to the rest of the body. Common symptoms of uncontrolled atrial fibrillation may include shortness of breath, shortness of breath when lying flat, dizziness, and sudden onset of shortness of breath during the night. This may progress to swelling of the lower extremities, a manifestation of congestive heart failure. Due to inadequate cardiac output, individuals with AF may also complain of light-headedness, may feel like they are about to faint, or may actually lose consciousness.

AF can cause respiratory distress due to congestion in the lungs. By definition, the heart rate will be greater than 100 beats per minute. Blood pressure may be variable, and often difficult to measure as the beat-by-beat variability causes problems for most digital (oscillometric) non-invasive blood pressure monitors. For this reason, when determining heart rate in AF, direct cardiac auscultation is recommended. Low blood pressure is most concerning and a sign that immediate treatment is required. Many of the symptoms associated with uncontrolled atrial fibrillation are a manifestation of congestive heart failure due to the reduced cardiac output. Respiratory rate will be increased in the presence of respiratory distress. Pulse oximetry may confirm the presence of hypoxia related to any precipitating factors such as pneumonia. Examination of the jugular veins may reveal elevated pressure (jugular venous distention). Lung exam may reveal crackles, which are suggestive of pulmonary edema. Heart exam will reveal a rapid irregular rhythm.

Holiday heart syndrome is an irregular heartbeat pattern presented in individuals who are otherwise healthy. Coined in 1978 the term is defined as "abnormal heart rhythms sometimes following excessive alcohol consumption; usually temporary".

Holiday heart syndrome can be the result of stress, dehydration, and drinking alcohol. It is sometimes associated with "binge drinking" common during the holiday season. The condition can also occur when individuals consume only moderate amounts of alcohol.

Irregular heartbeats can be serious. If palpitations continue for longer than a few hours patients should seek medical attention. Some arrhythmias associated with HHS after binge drinking can lead to sudden death, which may explain some of the sudden death cases commonly reported in alcoholics. Atrial fibrillation is the most common arrhythmia in holiday heart syndrome. Symptoms usually resolve themselves within 24 hours.

Holiday heart can also cause abnormal burning sensation whilst urinating and/or the feeling of passing blood similar to a kidney stone. This generally subsides in days or weeks.

AF is usually accompanied by symptoms related to a rapid heart rate. Rapid and irregular heart rates may be perceived as palpitations or exercise intolerance and occasionally may produce anginal chest pain (if the high heart rate causes ischemia). Other possible symptoms include congestive symptoms such as shortness of breath or swelling. The arrhythmia is sometimes only identified with the onset of a stroke or a transient ischemic attack (TIA). It is not uncommon for a patient to first become aware of AF from a routine physical examination or ECG, as it often does not cause symptoms.

Since most cases of AF are secondary to other medical problems, the presence of chest pain or angina, signs and symptoms of hyperthyroidism (an overactive thyroid gland) such as weight loss and diarrhea, and symptoms suggestive of lung disease can indicate an underlying cause. A history of stroke or TIA, as well as high blood pressure, diabetes, heart failure, or rheumatic fever may indicate whether someone with AF is at a higher risk of complications. The risk of a blood clot forming in the left atrium, breaking off, and then traveling in the bloodstream can be assessed using the CHADS2 score or CHA2DS2-VASc score.

Signs and symptoms can arise suddenly and may resolve without treatment. Stress, exercise, and emotion can all result in a normal or physiological increase in heart rate, but can also, more rarely, precipitate SVT. Episodes can last from a few minutes to one or two days, sometimes persisting until treated. The rapid heart rate reduces the opportunity for the "pump" to fill between beats decreasing cardiac output and as a consequence blood pressure. The following symptoms are typical with a rate of 150–270 or more beats per minute:

- Pounding heart

- Shortness of breath

- Chest pain

- Rapid breathing

- Dizziness

- Loss of consciousness (in only the most serious cases)

For infants and toddlers, symptoms of heart arrhythmias such as SVT are more difficult to assess because of limited ability to communicate. Caregivers should watch for lack of interest in feeding, shallow breathing, and lethargy. These symptoms may be subtle and may be accompanied by vomiting and/or a decrease in responsiveness.

Roemheld syndrome (RS), also known as Roemheld-Techlenburg-Ceconi-Syndrome or gastric-cardia, is a complex of gastrocardiac symptoms first described by Ludwig von Roemheld (1871–1938). It is a syndrome where maladies in the gastrointestinal tract or abdomen are found to be associated with cardiac symptoms like arrhythmias and benign palpitations. There is rarely a traceable cardiac source to the symptoms which may lead to a lengthy period of misdiagnosis.

An episode of SVT may present with palpitations, dizziness, shortness of breath, or losing consciousness (fainting). The electrocardiogram (ECG) would appear as a narrow-complex SVT. Between episodes of tachycardia the affected person is likely to be asymptomatic, however, the ECG would demonstrate the classic delta wave in Wolff–Parkinson–White syndrome.

Orthostatic hypotension, also known as postural hypotension, occurs when a person's blood pressure falls when suddenly standing up from a lying or sitting position. It is defined as a fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg when a person assumes a standing position. It occurs predominantly by delayed constriction of the lower body blood vessels, which is normally required to maintain an adequate blood pressure when changing position to standing. As a result, blood pools in the blood vessels of the legs for a longer period and less is returned to the heart, thereby leading to a reduced cardiac output. Mild orthostatic hypotension is common and can occur briefly in anyone, although it is prevalent in particular among the elderly and those with known low blood pressure. Severe drops in blood pressure can lead to fainting, with a possibility of injury.

There are numerous possible causes for orthostatic hypotension, such as certain medications (e.g. alpha blockers), autonomic neuropathy, decreased blood volume, and age-related blood vessel stiffness.

Apart from addressing the underlying cause, orthostatic hypotension may be treated with a recommendation to increase salt and water intake (to increase the blood volume), wearing compression stockings, and sometimes medication (fludrocortisone, midodrine or others).

Difficulty breathing, a cardinal symptom of left ventricular failure, may manifest with progressively increasing severity as the following:

- Difficulty breathing with physical activity (exertional dyspnea)

- Difficulty breathing while lying flat (orthopnea)

- Episodes of waking up from sleep gasping for air (paroxysmal nocturnal dyspnea)

- Acute pulmonary edema

Other cardiac symptoms of heart failure include chest pain/pressure and palpitations. Common noncardiac signs and symptoms of heart failure include loss of appetite, nausea, weight loss, bloating, fatigue, weakness, low urine output, waking up at night to urinate, and cerebral symptoms of varying severity, ranging from anxiety to memory impairment and confusion.

The hallmark sign of POTS is a measured increase in heart rate by at least 30 beats per minute within 10 minutes of assuming an upright position. For people aged between 12 and 19, the minimum increase for diagnosis is 40 beats per minute. This symptom is known as orthostatic (upright) tachycardia (fast heart rate). It occurs without any coinciding drop in blood pressure, as that would indicate orthostatic hypotension. It should be noted, however, that certain medications to treat POTS may cause orthostatic hypotension. It is accompanied by other features of orthostatic intolerance—symptoms which develop in an upright position and are relieved by reclining. These orthostatic symptoms include palpitations, light-headedness, chest discomfort, shortness of breath, nausea, weakness or "heaviness" in the lower legs, blurred vision and cognitive difficulties. Symptoms may be exacerbated with prolonged sitting, prolonged standing, alcohol, heat, exercise, or eating a large meal.

In up to one third of people with POTS, fainting occurs in response to postural changes or exercise. Migraine-like headaches are common, sometimes with symptoms worsening in an upright position (orthostatic headache). Some people with POTS develop acrocyanosis, or blotchy, red/blue skin upon standing, especially over the feet (indicative of blood pooling). 48% of people with POTS report chronic fatigue and 32% report sleep disturbances. Others exhibit only the cardinal symptom of orthostatic tachycardia.

POTS can co-occur in all types of Ehlers–Danlos syndrome (EDS), a hereditary connective tissue disorder marked by loose hypermobile joints prone to subluxations and dislocations, skin that exhibits moderate or greater laxity, easy bruising, and many other symptoms. A trifecta of POTS, EDS, and Mast Cell Activation Syndrome (MCAS) is becoming increasingly more common, with a genetic marker common among all three conditions. POTS is also often accompanied by vasovagal syncope, with a 25% overlap being reported. There is significant overlap between POTS and chronic fatigue syndrome, with evidence of POTS in 25–50% of CFS cases. Fatigue and reduced exercise tolerance are prominent symptoms of both conditions, and dysautonomia may underlie both conditions.

Symptoms of Da Costa's syndrome include fatigue upon exertion, shortness of breath, palpitations, sweating, and chest pain. Physical examination reveals no physical abnormalities causing the symptoms.

Patients who suffer from acute OI usually manifest the disorder by a temporary loss of consciousness and posture, with rapid recovery (simple faints, or syncope), as well as remaining conscious during their loss of posture. This is different from a syncope caused by cardiac problems because there are known triggers for the fainting spell (standing, heat, emotion) and identifiable prodromal symptoms (nausea, blurred vision, headache). As Dr. Julian M. Stewart, an expert in OI from New York Medical College states, "Many syncopal patients have no intercurrent illness; between faints, they are well."

Symptoms:

- Altered vision (blurred vision, "white outs"/gray outs, black outs, double vision)

- Anxiety

- Exercise intolerance

- Fatigue

- Headache

- Heart palpitations, as the heart races to compensate for the falling blood pressure

- Hyperpnea or sensation of difficulty breathing or swallowing (see also hyperventilation syndrome)

- Lightheadedness

- Sweating

- Tremulousness

- Weakness

A classic manifestation of acute OI is a soldier who faints after standing rigidly at attention for an extended period of time.

Ventricular tachycardia (V-tach or VT) is a type of regular and fast heart rate that arises from improper electrical activity in the ventricles of the heart. Although a few seconds may not result in problems, longer periods are dangerous. Short periods may occur without symptoms or present with lightheadedness, palpitations, or chest pain. Ventricular tachycardia may result in cardiac arrest and turn into ventricular fibrillation. Ventricular tachycardia is found initially in about 7% of people in cardiac arrest.

Ventricular tachycardia can occur due to coronary heart disease, aortic stenosis, cardiomyopathy, electrolyte problems, or a heart attack. Diagnosis is by an electrocardiogram (ECG) showing a rate of greater than 120 bpm and at least three wide QRS complexes in a row. It is classified as non-sustained versus sustained based on whether or not it lasts less than or more than 30 seconds. The term "ventricular tachycardias" refers to the group of irregular heartbeats that includes ventricular tachycardia, ventricular fibrillation, and torsades de pointes.

In those who have a normal blood pressure and strong pulse, the antiarrhythmic medication procainamide may be used. Otherwise immediate cardioversion is recommended. In those in cardiac arrest due to ventricular tachycardia cardiopulmonary resuscitation (CPR) and defibrillation is recommended. Biphasic defibrillation may be better than monophasic. While waiting for a defibrillator, a precordial thump may be attempted in those on a heart monitor who are seen going into an unstable ventricular tachycardia. In those with cardiac arrest due to ventricular tachycardia survival is about 45%. An implantable cardiac defibrillator or medications such as calcium channel blockers or amiodarone may be used to prevent recurrence.

Although there are many signs and symptoms associated with PVCs, PVCs may have no symptoms at all. An isolated PVC is hard to catch without the use of a Holter monitor. PVCs may be perceived as a skipped heart beat, a strong beat, or a feeling of suction in the chest. They may also cause chest pain, a faint feeling, fatigue, or hyperventilation after exercise. Several PVCs in a row becomes a form of ventricular tachycardia (VT), which is a potentially fatal abnormal heart rhythm. Overall it has been seen that the symptom felt most by patients experiencing a PVC is the mere perception of a skipped heartbeat. The more frequently these contractions occur, the more likely there are to be symptoms, despite the fact that these beats have little effect of the pumping action of the heart and therefore cause minimal if any symptoms.

Some other possible signs and symptoms of PVCs:

- Abnormal ECG

- Irregular heart beat

- Dyspnea

- Dizziness

- Feeling your heart beat (palpitations)

- Feeling of occasional, forceful beats

- Increased awareness of your heart beat

- Perception of a skipped heartbeat