Tachycardia

Definition: What is tachycardia?

The medical term tachycardia refers to a racing heartbeat, defined by a heart rate over 100 beats per minute. In children, age-specific heart rate thresholds apply. The cause of such tachycardias can be harmless, for example during excitement or anxiety. However, if the tachycardia remains persistent, it may indicate an underlying heart condition or, in some cases, may even require emergency treatment.

The heart is the central organ of the body, pumping blood throughout the entire circulatory system. It collects blood from the veins, rhythmically contracts and ejects the blood into the arteries to the organs.

An excessively high heart rate carries the danger of not leaving the heart enough time to fill with blood. As a result, too little blood is ejected, leading to insufficient blood supply to the organs. To be able to determine the cause of the tachycardia and initiate treatment, the heart should be examined by a specialized physician.

What are the types of tachycardia?

Tachycardias are differentiated by their site of origin. To better understand this, it is helpful to visualize the structure of the heart.

The heart is divided into a right and left side, each consisting of an atrium and a ventricle. The right atrium receives the oxygen-poor blood from the veins. This blood flows from the right atrium into the right ventricle and is pumped into the lungs. There the blood is oxygenated and can return to the left atrium. From the left ventricle, the oxygen-rich blood is ejected into the systemic circulation.

The heart must contract rhythmically to adequately eject blood. It has its own electrical conduction system that stimulates the muscle cells to contract uniformly. The sinus node is the central pacemaker and is located in the right atrium. The electrical impulse is conducted through specialized heart cells into both atria and ventricles, exciting heart muscle cells. This causes a rhythmic contraction of the atria and ventricles.

Tachycardias are classified into the following types:

• Supraventricular tachycardia: originates outside of the ventricles, typically in the atria
• Ventricular tachycardia: originates inside the ventricles

Is tachycardia dangerous?

A normal resting heart rate in adults ranges between 60 and 80 beats per minute. During tachycardia, the heart rate persistently stays above 100 beats per minute. A sustained heart rate over 120 can be concerning, while rates over 150 can even be life-threatening.

However, not all tachycardias are caused by a serious condition. It is often a physiological response of the heart to physical stress or excitement. In order to maintain adequate circulation during such situations, the heart temporarily increases its rate and returns to normal shortly after.

Even sudden episodes of a racing heartbeat during rest can be harmless palpitations. While these episodes can be scary, they are generally considered harmless.

Tachycardia can be dangerous if it is caused by an underlying heart condition. These cases prompt treatment to prevent long-term damage or the development of life-threatening arrhythmias.

Causes: What causes tachycardias?

Tachycardia can present as an independent condition or as a symptom of an underlying heart disease. Tachycardia can occur in the following conditions:

• Coronary artery disease
• Potassium deficiency
• Hyperthyroidism
• Alcohol consumption
• Infection and inflammation
• Arrhythmias
• Sepsis
• Anemia
• Hypoglycemia
• Allergic reactions

Moreover, brief episodes of tachycardia can be triggered by excessive caffeine intake or as a side effect of certain medications.

If the tachycardia develops directly in the heart, two mechanisms are responsible for its development:

The first mechanism is referred to as focal impulse formation. Independent electrical impulses are generated at various locations in the heart, causing a rapid contraction of the heart muscle cells.

The second mechanism involves reentry circuits or reentrant excitation. In these cases, electrical signals are no longer transmitted through the regular conduction system. Due to partial blockages of certain conduction pathways, the excitation is redirected. This results in a circular conduction pathway causing a rapid and irregular heartbeat.

AV Nodal Reentrant Tachycardia (AVNRT)

AVNRT is the most common type of supraventricular tachycardia. The rapid heartbeat originates above the ventricles, specifically in the atrioventricular (AV) node. The AV node is the second major pacemaker after the sinoatrial (SA) node. Due to its location, it conducts electrical impulses from the atria to the ventricles. This condition is most commonly found in young and healthy individuals.

In the case of AVNRT, the AV node has not just one but two conduction pathways, one conducting more rapidly than the other. Since both pathways can conduct electrical impulses, this can lead to paroxysmal episodes of tachycardia.

Affected individuals often report episodes of heart racing, lasting from a few minutes to several hours. In most cases, these episodes resolve as abruptly as they appear. In patients without any heart conditions, no other symptoms are generally reported. However, in patients with underlying heart disease, AVNRT can cause a drop in blood pressure, chest tightness, or even circulatory collapse.

Symptoms of tachycardia

Affected individuals typically experience, apart from a pounding or racing heart, the following symptoms:

• Sweating and clammy hands
• Dizziness
• Rapid breathing or shortness of breath
• Trembling and inner restlessness
• Nausea

Diagnostics: How is tachycardia diagnosed?

The diagnostic process of tachycardia always begins with a thorough medical history. Detailed questions are asked about the tachycardia. These include the first occurrence, associated circumstances, accompanying symptoms, preexisting medical conditions, and current medication use.

This is followed by a physical examination, during which pulse and blood pressure are measured. Moreover, the physician palpates and auscultates the organs. Blood samples are also collected for laboratory testing.

An essential diagnostic tool is the electrocardiogram (ECG). It allows for quick, non-invasive assessment of cardiac function and provides valuable information about potential heart conditions. However, it only captures heart activity for a short period of time, hence why some arrhythmias may be missed. Therefore, when tachycardia is suspected, a 24-hour Holter ECG is recommended. The patient wears a portable ECG device for 24 hours which allows continuous monitoring of the heart.

Additional tests may be required. For example, a stress ECG, a heart ultrasound (echocardiography) and 24-hour blood pressure monitoring.

Treatment: How are tachycardias treated?

The treatment of tachycardia should always address the underlying cause. Furthermore, it must be determined whether the tachycardia is pathological. If it’s not clinically relevant, treatment is generally not necessary. However, certain maneuvers can help reduce the heart rate during episodes of tachycardia.

These maneuvers are called vagal maneuvers as they stimulate the vagus nerve, which lowers the heart rate. Patients can take a sip of cold water or massage specific points around the carotid arteries in the neck. Moreover, performing deep breaths and abdominal tensing can be useful.

If a tachyarrhythmia is present, an adequate treatment plan should be followed.

This involves medications that control the heart rate and rhythm. They can be taken long-term or during acute episodes.

If the tachycardia is life-threatening, or not responsive to vagal maneuvers or medications, an electrical cardioversion may become necessary. This involves brief electric shocks to restore normal rhythm.

If the tachycardia is caused by abnormal impulses or accessory conduction pathways, cardiac ablation may be an option. The affected cardiac cells are ablated during the procedure, allowing the conduction system to return to its normal rhythm.

If hypertension is present, medications that lower blood pressure while offering cardioprotective effects should be considered. Moreover, lifestyle changes can contribute to a reduction of blood pressure. These may include dietary changes, regular physical activity, and smoking cessation.

If the tachycardia is caused by hyperthyroidism, treatment includes thyroid surgery or anti-thyroid medications. Radioiodine therapy is also a suitable option. The goal of the treatment is to restore normal thyroid hormone levels.

Chronic stress can lead to pathological tachycardia. Stress reducing measures such as occupational changes, improved sleep hygiene, or therapy can have a positive impact on the heart.

Prognosis and disease progression

The course of tachycardia depends on its underlying cause. Thus, there is no general prediction regarding the prognosis or progression. However, conditions that are identified and treated at an early stage, generally have a significantly better prognosis and contribute to a higher life expectancy.

The primary goal of treatment is the prevention of life-threatening cardiac arrhythmias.

What physicians and clinics are specialists in tachycardia?

As tachycardia may be a sign of an underlying serious condition, a thorough diagnostic evaluation is crucial. Physicians with a specialty in the field of cardiology are specialists in the diagnosis and treatment of tachycardia. Regarding the treatment, it is recommended to also consult internal medicine specialists or cardiothoracic surgeons.

All physicians listed here have been carefully selected based on their high level of expertise. They are all specialists in their respective fields with extensive experience in the treatment of tachycardia. See for yourself the qualifications of our experts and schedule a consultation quickly and easily.