It is characterized by an altered and speedy heart rate.
In adults, the heartbeats typically 60-100 times per minute. A heart rate greater than 100 beats per minute is called tachycardia. Tachycardia can occur in both children and adults.
In newborns and infants, tachycardia is defined when the heart rate is more significant than 150 beats per minute.
There are numerous causes of tachycardia, and the condition is prevalent. Although some forms are harmless, others are potentially lethal.
Tachycardia can be caused by exertion, strenuous exercise, emotions, hyperthyroidism (overactive thyroid gland), diseases, injuries, heart disorders, or exposure to certain drugs or chemicals.
The primary function of the heart
The heart has two upper chambers (atria) and two lower chambers (ventricles).
The atria and ventricles have muscular walls.
A heartbeat occurs when this muscle suddenly contracts (squeezes) so that the chambers get smaller and the blood inside is expelled.
Control of the heartbeat begins with a small group of cells in the right atrium, called the sinoatrial node (the heart’s natural pacemaker).
The sinoatrial node generates electrical signals that control the heartbeat’s speed (heart rate) and pattern (rhythm).
These impulses cause the atria to contract and pump blood into the ventricles.
The sinoatrial node also sends electrical impulses to another collection of cells, the atrioventricular node.
The atrioventricular node conducts impulses down an electrical pathway to the ventricles, which contract and pump blood from the heart to the lungs and the rest of the body.
The atrioventricular node determines the rate of contraction of the ventricles. The pulse felt in the wrist is due to the contraction of the ventricles.
Any abnormal heart rate or rhythm is called an arrhythmia.
Tachycardia is a type of arrhythmia in which the electrical signals that control the heart travel through the heart faster than usual, causing the heart to beat too fast.
Types and symptoms of tachycardia
Sinus tachycardia is a rhythm formed by the electrical impulse originating from the atrioventricular node in the usual way. However, the rate is faster than average.
The average heart rate range is 50-100 beats per minute in adults.
The rate of sinus tachycardia is 150 beats per minute.
It is also not unusual for the PR and QT intervals to decrease in length with higher rates.
This is a familiar rhythm that is entirely normal in response to any of a variety of stimuli.
There are situations in which the appearance of sinus tachycardia is entirely typical:
- In response to a daily exercise (appears even when you usually are climbing a flight of stairs).
- Anxiety or some other emotional disorder.
- When you have a fever.
- During pregnancy.
- By ingesting too much caffeine or alcohol.
- When you smoke.
There are also situations in which the accelerated heart rate arises in response to abnormal physiological conditions, such as:
- Variations in blood pressure.
- In cases of heart failure.
- When the individual suffers from heart disease.
- When there is a myocardial attack.
The average maximum heart rate of a patient decreases with age.
At age 16, peak rates under exertion of 220 beats per minute would not be unusual.
However, by age 50, the same peak rate of people under exertion can drop to 160 beats per minute.
People with sinus tachycardia often have rapid rates of heart palpitations, dizziness, confusion, or various symptoms related to the condition.
Generally, no treatment is recommended when the patient has sinus tachycardia.
However, if sinus tachycardia arises when the patient is sitting, or without doing any activity, it is necessary to indicate some medications.
Sinus tachycardia is rarely a primary cardiac arrhythmia and is almost always caused by one of the above conditions.
Sinus tachycardia syndrome has been described and is a form of autonomic dysfunction.
Sinus node modification or ablation procedures can be performed. However, they present a risk of causing significant sinus node dysfunction, requiring implantation of a pacemaker.
Ventricular tachycardia specifically refers to tachycardia that starts in the heart’s ventricles.
In the case of ventricular tachycardia, a periodic electrical signal is sent from the ventricles but with a high-speed frequency.
If the heart rate remains high for more than 30 seconds, then ventricular tachycardia is a life-threatening condition.
In these cases, cardiac arrest can occur.
A person with ventricular tachycardia may require an electric shock or medications to change the arrhythmia to normal sinus rhythm.
Ventricular tachycardia can cause the following symptoms:
- Pressure or pain in the chest.
- Fainting is also known as syncope or near syncope.
- Lightheadedness or dizziness
- Palpitations, which may skip, flap, or beat in the chest.
- Short of breath.
It is important to note that children may not know how to describe what they feel during a period of ventricular tachycardia.
They may have trouble keeping up with other children or find that they are having discomfort and want to sit up and rest.
Sometimes a child may not experience any symptoms at all.
If the heart rate during an episode of ventricular tachycardia is extremely fast or continues for several seconds, you may experience some or all of these symptoms.
- Palpitations or a feeling that your heart is beating very fast.
- Slight pain in the chest.
- Some trouble breathing.
- Dizziness or vertigo
Supraventricular tachycardia begins in the area of the heart above the ventricles.
When the heart usually beats, its muscle walls contract (tighten) to push blood out and around the body.
Then they relax so that the heart can fill with blood again.
This process is repeated for each heartbeat.
In supraventricular tachycardia, the heart muscle contracts so fast that it cannot relax between contractions.
This reduces the amount of blood pumped around the body, which can lead to dizziness and shortness of breath.
Supraventricular tachycardia is a heart condition that features abnormally fast heart rate episodes.
Episodes can last for seconds, minutes, hours, or (in rare cases) days.
They can occur regularly, several times a day, or occasionally, once or twice a year.
The heart rate can be as high as 250 beats per minute but is generally between 140 and 180 (compared to a normal heartbeat which should be 60 to 100 beats per minute at rest).
Usually, heart palpitations (noticeable heartbeats) and a rapid pulse are felt.
Supraventricular tachycardia is caused by abnormal electrical impulses that start suddenly in the heart’s upper chambers (the atria).
The presence of these impulses can modify the natural rhythm of the heart.
A short circuit in the heart’s electrical system often causes these spontaneous impulses.
The short circuit causes an electrical signal to travel continuously around a circle.
Each time the signal completes the circuit, the impulse spreads to the rest of the heart, forcing it to beat rapidly.
The presence of supraventricular tachycardias, in general, is not very risky.
They are not due to a “heart attack,” In children with healthy hearts, they do not cause sudden death.
However, if they occur very often or over long periods (hours or days), then they can cause difficulties with the pumping action of the heart and pose much risk if not treated in time.
There are many additional subtypes of supraventricular tachycardia:
- Atrioventricular node reentry tachycardia: is a shunt near the atrioventricular node. Special cells near the atrioventricular node allow the impulse to travel at different speeds. A circuit is created when the impulse leaves the fast cells and returns through the dead cells.
- Atrial flutter: the impulse travels around the atria in a circular pattern causing the heart to beat faster.
- Atrioventricular Reciprocal Tachycardia: The impulse starts typically but travels back to the atria through an additional pathway between the atrium and the ventricle. This type of tachycardia is most often associated with Wolff-Parkinson-White syndrome.
- Atrial tachycardia: The impulse begins in a small area of abnormal tissue within the atria and causes the heart to beat faster.
- Junctional tachycardia: The abnormal impulse starts from the atrioventricular node between the atria and the ventricles. This type is more common after heart surgery.
There are specific symptoms that are commonly experienced in these types, and they are:
- Dizziness or lightheadedness
- Syncope (fainting)
- Sharp chest pain, also called angina pectoris.
- Excessive palpitations.
Diagnosis of tachycardias
Several different types of procedures can be used to diagnose tachycardias:
An EKG is a measure of the electrical activity of the heart.
When electrodes are placed on specific places on the body such as the chest, arms, and legs, a graphical representation, or trace, of the electrical activity of the heart is obtained through the EKG equipment.
An electrocardiogram indicates the presence of arrhythmias if there is damage to the heart caused by ischemia or lack of oxygen in the heart muscle, the occurrence of myocardial infarction (or heart attack), or a problem with the heart valves or some other type of affection in the heart.
Currently, there are several types of tests performed with the help of electrocardiograms, such as:
The resting electrocardiogram: In this procedure, small sticky patches called electrodes are attached to the chest, arms, or legs. The electrodes are, in turn, connected to the electrocardiogram equipment.
The electrocardiogram machine records the heart’s electrical activity for about a minute. The patient is lying down during this EKG.
Stress test: The patient exercises by walking on a treadmill or pedaling a stationary bike while the EKG is recorded during the test. This test assesses changes in the EKG during activities, such as exercise, that cause stress.
Electrophysiological studies: These are a test in which a small, thin tube called a catheter is inserted into a large blood vessel in the leg or arm and from there to the heart.
This gives the physician the ability to find the site of origin of the arrhythmia within the heart tissue, thus determining how to treat it. Sometimes an attempt to treat the arrhythmia can be made by ablating at the study time.
The electrodes are passed through the blood vessels to the heart to record the electrical signals in the electrophysiological study. This analysis creates a detailed map of the electrical circuits and detects anomalies.
Additionally, this procedure can induce arrhythmias, allowing the physician to evaluate the effectiveness of medications for treatment.
A Holter monitor is a continuous recording of an electrocardiogram made over 24 hours. The electrodes are attached to the patient’s chest and then connected to a miniature portable EKG recording equipment via cables.
The patient goes about their daily activities during this procedure.
Holter monitoring can be performed when an arrhythmia is suspected but not seen on a resting EKG, as arrhythmias can be transient and not seen during the shorter recording times of the resting EKG.
Event Monitor – This is similar to a Holter monitor, but the EKG is recorded only when the patient begins to feel symptoms. These event monitors can be used longer than Holter monitors. The monitor can be removed to allow showering or bathing.
Mobile heart monitoring – This is similar to Holter and event monitor. The electrocardiogram is constantly monitored to detect arrhythmias, which are recorded and sent to your doctor regardless of whether or not symptoms are present.
Recordings can also be initiated by the patient when symptoms are felt. Monitors can be used for 30 days.
Echocardiogram: A transducer sends ultrasound waves through the chest to create a visual image of moving structures in the heart.
The treatment to be administered will be adapted according to the severity of the symptoms experienced.
As well as, the presence of other conditions such as diabetes, kidney failure, or heart failure can disrupt the ordinary course of treatment.
The doctor usually suggests lifestyle modifications such as withdrawal of caffeine, alcohol, or any other substance possibly causing the condition.
In cases where stress is suspected of causing tachycardia, measures to reduce the stress level are generally recommended, with therapies such as meditation, stress management therapies, exercise programs, or psychotherapy.
If the doctor chooses to use medications, the decision of which medication to use will be determined by the severity of the symptoms, other conditions that may be present, and other medications the patient is already taking.
Medicines can slow or regulate your heart rate.
Certain medications may require a brief hospital stay while the body adjusts.
Examples of these medications include:
- Calcium channel blockers are a group of drugs that lower blood pressure by relaxing the cells of the heart muscle.
- Beta-blockers treat heart conditions, and digoxin is a drug that slows down the heart rate.
Other medications can convert tachycardia to a normal rhythm, such as amiodarone, propafenone, and flecainide.
Blood thinners are drugs that manipulate the blood clotting process (called plasma clotting).
They inhibit the formation of thrombi, which means that they prevent blood clots from forming.
Clotting can cause a stroke or heart attack.
Blood thinners, such as warfarin, can be used to prevent blood clots from forming in the arteries.
Radiofrequency catheter ablation
In catheter ablation, catheters are inserted through blood vessels in the heart to heat or freeze tissue and destroy (remove) abnormal electrical conduction pathways.
Providing relief for patients who may not respond well to medication, prefer not to take medication, or cannot take medication.
Ablation is commonly used to treat Wolff-Parkinson-White syndrome, atrial fibrillation, and atrial flutter.
The procedure involves threading a small metal-tipped catheter through a vein or artery in the leg and into the heart.
In those cases where fluoroscopy or X-rays are used, the catheter is guided through the blood vessel until it reaches the heart.
Extra catheters inserted through the vein in the leg and neck contain electrical sensors to find the area causing the arrhythmia. This procedure is called mapping.
The metal-tipped catheter is maneuvered to each site in the heart that causes the irregular heartbeat.
Radiofrequency waves or currents are sent through the tip of the catheter, cauterizing or burning cells to destroy additional electrical pathways that cause abnormal heart rhythms.
Cryoablation, sometimes called cryopreservation, is similar to radiofrequency catheter ablation in that it is a procedure that interrupts the abnormal electrical pathway in the heart.
However, instead of burning cells, cryoablation destroys cells by freezing them.
Cryoablation has been very effective in treating children with arrhythmias.
Like radiofrequency catheter ablation, cryoablation involves threading a small metal-tipped catheter through a vein or artery in the leg and into the heart.
The catheter is guided through the blood vessel to the heart using fluoroscopy or x-ray techniques.
Extra catheters, inserted through the vein in the leg and neck, contain electrical sensors to help “map” or find the area causing the arrhythmia.
The metal-tipped catheter is maneuvered into the areas of the heart that are causing the irregular heartbeat.
Cryoablation then freezes extra cells or electrical pathways that cause abnormal heart rhythms.
Implantable cardioverter defibrillator
An implantable cardioverter-defibrillator is not a cure for heart rhythm problems, but it can stop a speedy heartbeat and bring it back to normal.
An implantable cardioverter-defibrillator is a small device, similar to a pacemaker, implanted under the skin, often in the shoulder area just below the collarbone.
The implantable cardioverter-defibrillator can detect the patient’s heart rate.
When the heart rate exceeds a speed programmed into the device, it delivers an electric shock to the heart to correct the rhythm to a slower, average heart rate.
This procedure stops certain arrhythmias, such as atrial fibrillation, supraventricular tachycardia, or atrial flutter.
The patient is connected to an EKG monitor, which is connected to a defibrillator.
An electric shock is delivered at the precise point during an EKG to turn the abnormal heart rhythm into a normal one.
Emergency asynchronous defibrillation
Defibrillation is similar to cardioversion, except that the procedure delivers higher energy shocks more quickly to convert life-threatening arrhythmias such as ventricular tachycardia and pulseless ventricular fibrillation.
In the case of arrhythmias, surgical treatment is usually carried out only when the possible options have already failed.
Surgical ablation is a major surgical procedure that requires general anesthesia.
The chest opens, exposing the heart.
After the arrhythmia site is located, the tissue is destroyed or removed to nullify the source of the arrhythmia.