Cardiac arrhythmia: Types, causes and symptoms

Are cardiac arrhythmias dangerous? What can I do against heart racing and fear? Which medications help? Please find answers to these and other questions in the following text.

Types

What are the different types of arrhythmias?

In cardiac arrhythmias your heart beats too slow, too fast or irregular. Also, single extra beats can disrupt your otherwise regularly beating heart. "Cardiac arrhythmia", as generic term, stands for a wide variety of different rhythm problems.

Electrical conduction of the heart

Normally, our heartbeat starts in an area of specialized cells, the so-called sinus node, which lies in the right upper chamber of our heart. These specialized cells generate electrical impulses which are transmitted to the heart muscle cells and initiate the cardiac contraction.

Yet, besides these specialized cells, any other cell of the heart can generate electrical impulses and thus disrupt the heart rhythm. In general, rhythm disturbances originate from cells either out of the upper or main chambers of the heart. Furthermore, sick sinus node and sick AV node (a conduction pathway between right upper and right main heart chamber) can lead to cardiac arrhythmias.

Whereas extra beats, for example, can be innocent and occur in completely healthy people, other types of arrhythmia may due to an underlying heart disease or due to another illness. Thyroid problems, medication overdoses or toxic substances like alcohol and drugs can also cause rhythm problems.

Too slow, too fast or irregular

A slow heartbeat below 60 beats per minute is called bradycardia, a fast heartbeat with rates above 100 beats per minute tachycardia. Arrhythmia refers to an irregular heartbeat with missing or additional occurring heartbeats.

Classic examples of arrhythmia include amongst others:

• Extra heartbeats (premature atrial contractions PACs and premature ventricular contractions PVCs)
• Atrial fibrillation and atrial flutter
• Sick Sinus Syndrome
• AV block (atrioventricular block)
• AV-nodal reentry tachycardia (AVNRT)
• WPW syndrome (Wolff-Parkinson-White syndrome)
• Ventricular tachycardias/ventricular fibrillation

Cardiac arrhythmias usually originate from different places of origin, vary in their underlying mechanisms as well as in signs and symptoms. Thus, also their treatment options differ. A rapid heartbeat, for example, may need to be slowed down with medications and patients with a very slow heartbeat may require a pacemaker supporting the heart.

Is a heartbeat of less than 60 beats per minute always abnormal?

Well-trained athletes performing competitive sports often have a heart rate below 60 beats per minute. Their heart muscle is better trained compared to people who do less or no sport.

In healthy people, the pulse rate varies between 50 to 60 and 100 to 110 beats per minute. Numbers provided vary a tiny bit. At rest and during sleep, the pulse is usually a little lower. During physical exertion on the contrast, it increases in order to pump a higher volume of blood and to meet the bodies needs for oxygen.

When to see your doctor

An athlete's heart, for example, pumps a high volume with each single heartbeat. Thus, few beats are enough to supply the body with sufficient blood. Even 30 beats per minute can be enough and still be normal in athletes.

For non-athletes, this may be different. If the heart rate falls below 50 beats per minute at rest, your doctor may want to check an ECG to exclude any sort of cardiac conduction disturbance. Typical tests include resting ECG, 24-hour long-term ECG, ultrasound of the heart (echocardiogram) and possibly stress testing with a treadmill or bicycle ECG. Particularly, if you experience dizziness, severe shortness of breath or fainting with a slow heartbeat, you must be quickly seen by a doctor.

On the other hand, various factors including illnesses like hyperthyroidism, fever, lung disease or anaemia can increase the pulse and go along with heart racing.

Causes

Can coronary artery disease lead to cardiac arrhythmias?

Coronary heart disease can affect the hearts conduction system including the so-called sinus node as well as the AV node. A right sided heart attack, for example, with an occlusion of the right coronary artery, can lead to a blockage of the AV node and to very slow heart rates.

Furthermore, heart attacks and severely decreased perfusion can also trigger so-called ventricular arrhythmias. These are potentially dangerous and at times even life-threatening rhythm disturbances that originate from one of the main heart chambers.

Which role plays potassium in cardiac arrhythmias?

The electrolyte potassium plays an important role in the metabolism of muscle and nerve cells as well as neuromuscular conduction and function. Extremely increased blood levels of potassium are called hyperkalaemia, extremely decreased ones hypokalaemia. Interestingly, both, hyper- and hypokalaemia can trigger or intensify cardiac arrhythmias like premature beats or atrial fibrillation, for example.

Potassium generates electrical voltage on cell walls

Nerve fibres, muscle cells and heart work based on electrical voltages. Small pumps and filters transport electrolytes like sodium, chloride and potassium through tiny channels in the cell walls from the outside to the inside of a cell and vice versa.

Since some of the elements are positively and others negatively charged, they create an electrical charge on the two sides of the cell wall. For example, you find 98% of potassium inside the cells (intracellular) and only 2 % outside the cells (extracellular). The electrical voltage difference allows nerves, muscles and heart to work.

Sinus node generates rhythm

The heart's inner clock, the specialized cells of the so-called sinus node, also work on basis of these electrical differences. They send out 60 to 100 electrical impulses per minute at regular intervals, which corresponds to our pulse. Special fibres transmit the excitation to each individual heart muscle cell, which then contracts and triggers the pumping action of the heartbeat.

As described, potassium plays an important role in these processes. That is why changes in electrolytes, particularly potassium, can have a great impact on heart rhythm and possibly trigger rhythm disturbances.

Heart stumbling and rhythm disturbances

Both increased and decreased potassium levels influence the electrical voltage at the cell walls. They can both disrupt the heartbeat. A variety of symptoms including heart stumbling and racing is possible.

This includes harmless premature beats and atrial fibrillation, as well as more complex and potentially dangerous tachycardia from the main heart chambers. In addition to fast rhythms, bradycardias with very slow pulses can occur.

If arrhythmias are due to low or high potassium, the most important therapeutic step is to normalize the potassium level. In adults, the blood potassium should lie above 3.6 mmol/l and below 5.0 mmol/l.

Muscle paralysis due to altered potassium

As mentioned, potassium is not only important for heart cells, but also for nerves and muscles. For example, the so-called neuromuscular excitability changes with high and low potassium: in severs even neuromuscular paralysis may result from hyper- or hypokalaemia.

Is it true that certain psychiatric drugs can cause cardiac arrhythmia?

Yes, possible side effects of neuroleptics (prescribed mainly for schizophrenia) can affect the heart. Both older and newer neuroleptics have been observed to cause cardiac arrhythmias. And in very rare cases, sudden cardiac death has even occurred.

For this reason, an electrocardiogram (ECG) should be checked before and after starting drug treatment. Special care should be taken in people with previous damage to the cardiovascular system and very low blood pressure.

Can antiarrhythmic medication itself trigger cardiac arrhythmia?

Yes, most cardiac rhythm medications can cause cardiac arrhythmias themselves, including even threatening ones. One exception are beta-blockers, which lower the pulse and protect the heart.

Particularly when starting antiarrhythmic drugs, caution is required, and effectiveness must be monitored. Especially for people with concomitant heart disease, hospitalization may be required in order to monitor heart rhythms and patients closely. Regular monitoring about every three months is usually recommended in the long term.

Signs & Symptoms

Which symptoms are caused by cardiac arrhythmias?

Cardiac arrhythmias do not always cause symptoms. Thus, some people may not even notice that they have a heart rhythm disorder.

Typical signs of an arrhythmia can include:

• Palpitations
• Heart racing
• Dizziness
• Shortness of breath
• Chest pain
• Brief episodes of unconsciousness in more severe cases
• Anxiety

While some people perceive these symptoms as severe and threatening, others do not notice a possibly even more severe cardiac arrhythmia at all.

Can I measure my own heart rate?

Yes, self-measurement of your pulse is even recommended particularly for older people. In this way, it is possible to identify a heartbeat that is too fast, too slow or irregular. In case of any abnormalities, the doctor can examine the heartbeat more closely.

How to check your own heart rate

Before you check your own heart rate, you should rest for five minutes. Sitting is enough. You also need a watch that counts seconds.

Take your second and third finger of one hand (for example your right hand) and place them on the pulse of your other (in our case left) forearm, slightly above the wrist (on the inside of the forearm). Very light pressure is enough.

Once you feel your pulse, count the pulse beats for 30 seconds. By doubling the value, you will get your heart rate per minute.

In addition to counting, you can look out for any irregular, arrhythmic heartbeats.

Is it possible to monitor arrhythmias long term?

Yes, permanent monitoring of cardiac arrhythmia, longer than the usual 24 hours, is possible. It can be useful if a 24-hour-ECG does not provide any meaningful results, but complaints occur repeatedly and at irregular intervals. Furthermore, permanent monitoring may be necessary if there is a risk of (life-threatening) heart rhythm disturbances.

For permanent monitoring devices like event recorders or loop recorders are used. These are recording devices that are implanted on one side of your chest, directly under your skin. Usually, you keep such a device for about 2 years. They can permanently record your ECG in everyday life. Often, the recorded data can be transmitted electronically to a central office.

Do cardiac arrhythmias always have to be treated?

Not every cardiac arrhythmia needs treatment. Physicians distinguish between harmless, potentially dangerous and acutely dangerous rhythm disturbances.

In case of symptoms like shortness of breath, dizziness or chest pain, though, medical treatment may be required. Acutely dangerous rhythm disorders can even go along with an increased risk of sudden cardiac death. Patients then need emergent treatment.

Cardiac arrhythmia: How can I deal with my anxiety?

Cardiac arrhythmias are often associated with unpleasant symptoms including fear and feeling anxious and insecure. Fortunately, however, many cardiac arrhythmias are not dangerous.

In the case of dangerous cardiac arrhythmias, the best way to combat anxiety is good and conscientious treatment. Do not forget to take your medications and to get regular check-ups. If you suffer from anxiety but only have harmless or well treated arrythmias, psychotherapeutic help can be useful. Do not be afraid to talk to your doctor about your fears and anxieties.

Sick leave

How long will I be on sick leave with an arrhythmia?

There is no general answer to this question. And, different countries approach this topic in different ways. The type of cardiac arrhythmia plays an important role, when your doctor decides, for how long you should stay away from work.

From stumbling and palpitations

Dizziness, insecurity, anxiety and in severe cases shortness of breath and heart complaints may go along with cardiac arrhythmias. Their clinical presentation varies widely and ranges from harmless extra heartbeats (premature atrial or ventricular contractions), which also affect healthy people, to atrial fibrillation and malignant rhythm disturbances, which can occur in the context of severe heart disease.

The time of recommended sick leave varies in general, depending on the type of arrhythmia, possible underlying heart disease and signs and symptoms a patient may have. Thus, several different factors play a role. In the following text you will find detailed information on sick leave for individual rhythm problems.

Sick leave with extra heartbeats

Extra beats are not rare and occur in heart-healthy people. Physicians differentiate between so-called premature atrial contractions (PACs) and premature ventricular contractions (PVCs). Your doctor will usually carry out a few examinations to exclude any medical or cardiac problem. The tests generally include an ECG (heart curve), a 24-hour long-term ECG, an ultrasound of the heart (echocardiography) if necessary, and blood tests, for example of the thyroid.

If heart muscle and heart valves are healthy and if the extra beats are inconspicuous in form and number, there is no reason to worry. In these cases, the premature extra beats may be unpleasant, but they are usually completely harmless. A (longer) sick leave is usually not necessary.

Sick leave in atrial fibrillation

Another example of a frequent rhythm disturbance is atrial fibrillation. Up to 15% of all people older than 70 years suffer from it. It can be permanent or occur occasionally, alternating with the "normal" (sinus) rhythm. If pulse rate and cardiac pumping function are working within normal limits, atrial fibrillation can be treated by physicians with relative ease.

However, people with this rhythm condition have an increased risk of stroke and may need to take strong blood thinners, depending on their personal risk of stroke. Only a physician can assess this.

If your atrial fibrillation is well controlled and “stable”, you can go to work. Yet, if your heart rate is too low or too fast or you experience shortness of breath, fainting spells and chest pain, you may need to stay at home for a few days. The duration of sick leave can range from a few days to several weeks. In severe cases you may even have to go to hospital for a few days.

Sick leave with AV-nodal reentry tachycardia

In AV-nodal reentry tachycardia (AVNRT) strong palpitations can appear suddenly, out of the blue. It typically affects younger people. An extra conducting pathway allows rapid, circular electrical excitation of the heart.

Patients can interrupt this type of arrhythmia by themselves by performing certain manoeuvres like drinking cold water or pressing against the abdominal wall after taking a deep breath. If this is not enough, there are drugs that can stop the circling, which are injected into the vein. In patients with frequent episodes of this type of arrhythmia, catheter ablation can be very helpful. With catheter ablation the extra pathway in the heart is obliterated and the arrhythmia can be cured long term.

People with AVNRT can usually go to work, as long as they do not suffer from too frequent episodes. After a catheter ablation, on the other hand, patients are usually unable to work for a few days (to weeks) and may have to abstain from sports and heavy carrying for a while.

Sick leave for potentially dangerous rhythm disturbances like ventricular tachycardia

Ventricular tachycardia forms another group of rhythm disturbance. They are potentially dangerous because they can lead to so-called ventricular fibrillation and circulatory failure, maybe even lead to sudden cardiac death. People with ventricular fibrillation (as well as ventricular flutter) often have a severe heart condition. They frequently suffer from advanced heart failure or have had one or more serious heart attacks. Ventricular tachycardia can also occur as a result of inflammation of the heart muscle.

Sick leave after hospital discharge

People with acute or frequent ventricular tachycardia must be admitted and treated in hospital. After discharge from the hospital, in general, they must remain at home and are unable to work until their situation hopefully improves.

Some patients may even need an internal defibrillator which looks similar like a pacemaker and remains inside your chest and heart long term. It monitors the heartbeat and intervenes in case of malignant rhythm disturbances.

Other patients may alternatively receive a so-called Life-Vest for a few months, which is some sort of detachable life jacket with an integrated defibrillator. It helps during the transition time, when physicians wait for the heart to improve and cannot yet assess with certainty whether a defibrillator is permanently necessary or not.

Authors: Dr. med. Susanne Endres, Dr. med. Julia Hofmann

Source:

Gerd Herold: Internal Medicine 2019; ISBN 978-3-9814660-8-9