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When we talk about heart rhythm disturbances, we usually mean all sorts of arrhythmias. However, we hear of a heart block quite often. What is a heart block, how do you recognize and treat it? We talk about this with dr. hab. n. med. Maciej Sterliński from the Department of Heart Rhythm Disorders, Institute of Cardiology in Anin.
- When we hear "heart block" it comes to our mind that the heart is blocking, but what exactly is this heart block?
Heart block and heart blocking are very common terms.
- Well, let's start professionally, medically from the beginning.
I would really start from the beginning, that is, with a short presentation of the structure of the heart and describing how the stimulation of the heart to contract appears and spreads. The heart consists of two atria and two chambers, separated by valves. Each ventricle, also through two valves, pumps blood into circulation in the body and in the lungs. In order for the heart muscle to contract rhythmically, it needs a sequential signal to work. This function is performed by a special group of cells forming the stimulus-conducting system. The natural pacemaker is the sinoatrial node, located on the wall of the right atrium, from where excitation is conducted to a very important area called the atrioventricular node, located at the junction of the atria and ventricles. From there, the impps follows successive paths, called His bundle branches (left and right), to successive filaments that distribute the impps across the ventricular muscle. The current that stimulates the heart is called electro-mechanical coupling. Nature has created perfect solutions that man tries to imitate.
- Can we use a comparison to illustrate it?
As a pictorial comparison, you can use the principles of engine operation: the heart is a pump, i.e. cylinders with pistons. In order for the engine to run smoothly, it needs an ignition system, i.e. a bundle of cables that distributes current with an accuracy of milliseconds. This bundle of cables is the stimulus-conducting system. If the ignition system fails, the engine loses performance, runs erratically, or cuts out. This comparison also applies quite well to the heart function and impulse conduction blocking disorders in the heart.
- So speakingcolloquially a heart block, we are expertly dealing with blocking the conduction of impulse through the heart?
Exactly in the heart's stimulus-conducting system.
- Where exactly does heart block come from? What is its cause?
Conduction disturbances may be acquired or, less frequently, congenital, manifested at birth or detected during fetal life. There is also a very rare group of progressive conduction disorders that are genetic, and therefore congenital, but worsen gradually with age. The latter two situations apply to children or young people, but are fortunately much rarer. Acquired disorders are an expression of various cardiovascular diseases or aging of the body and constitute the vast majority of cases examined by cardiologists. From the point of view of the threat to our patients, the efficiency of the atrioventricular node, the main "transmission station" of stimulation to the ventricles, is of key importance. If the signal to contract the ventricles, i.e. the main pump that transports blood to the body, is blocked there, it can have very serious consequences. Fortunately, the cells of the stimulus-conducting system below the node have their own automatism, which can be a form of emergency power supply, but this mechanism can wear out quickly.
- Do cardiologists have any division in the severity of the disease?
We are talking about "heart block" here, so we are talking about various forms of conduction disorders, but let's focus on the atrioventricular node. Blocking in this node has three stages: the first (called by some people an increase in conduction time to the ventricles), which is not yet threatening. The second, when every impps generated in the atria is not conducted to the ventricles and - as a consequence, any contraction of the heart is absent. Third, and the most dangerous - called total, when the conduction in a node stops. These disorders can be paroxysmal or permanent.
- Accompanied by any symptoms?
They may be accompanied by various severity of symptoms, including loss of consciousness. However, for us doctors, the detailed mechanism of the block formation in the node is also important: is it more due to "fatigue" or damage to the node. We can distinguish it on the basis of the EKG, but this is more specialist knowledge. All these elements mean that we can assess the risk of the patient and, depending on the stage of the disease, carefully observe or counteract it properly. Grades: The second and third are called higher-degree AV blocks and atthe vast majority of cases require urgent treatment. Conduction disturbances in people with permanent atrial fibrillation are a separate form of atrioventricular block. These patients no longer have the possibility of regpiring their heart rhythm by the sinoatrial node, because its function is somewhat "jammed" by the irregular electrical activity of the atria. Conduction into the ventricles becomes irregular - hence the historical name of atrial fibrillation: complete arrhythmia. When the function of the atrioventricular node is impaired, the heart rate in such patients becomes more and more regular, but also slows down significantly.
- Such patients are treated differently?
For these patients, there are also special criteria for the diagnosis of second and third degree block. The occurrence of both permanent atrial fibrillation and conduction disturbances correlates with the age of the patients; this issue is the domain of cardiology in the elderly. At this point, I must emphasize that atrial fibrillation, due to its commonness, is in a sense a social problem of modern he althcare, and its comprehensive treatment - not only with the use of stimulation, but also with the help of pharmacotherapy or other surgical techniques, such as transvascular ablation, is very important.
- You said about the elderly, are they particularly vulnerable?
Conduction disturbances can occur at any stage of life, but they occur more and more frequently with subsequent decades of life. Elderly people suffer from various diseases of the circulatory system, or even people with a previous sense of he alth experience a natural "aging" of the stimulus-conducting system, which becomes less and less efficient. In the eighth-ninth decade of life, we most often encounter conduction disturbances in permanent atrial fibrillation. If we add that the elderly are particularly vulnerable to the consequences of injuries and disabilities, it is easy to understand that keeping them from working their hearts too slowly - and consequently weakening or fainting - is crucial for their functioning.
- So we already know what a heart block is, what it is, but may the patient not know that they have a heart block?
The patient rarely knows that he or she just has a "heart block". However, there are symptoms that may prompt you to go to a doctor or hospital quickly.
- What?
These include sudden weakness, dizziness, pre-syncope, or loss of consciousness. Enoughrarely, but unfortunately, the first symptom may also be a sudden cardiac arrest, and the ability to provide first aid is important here.Because the well-being and tolerance of certain disease states vary greatly from person to person, it happens that people with advanced atrioventricular conduction disorders feel quite well or they attribute a slight malaise to trivial causes and do not complain particularly about their he alth. Then the block may be diagnosed accidentally during a visit to the doctor or a routine ECG test.
- So, what is the diagnostic procedure for heart block?
Each problem with which we report to the doctor requires collecting a detailed interview, i.e. information about what the patient is complaining about, what he is suffering from, what medications he takes and what his environment is. It is also necessary to examine the patient and prescribe basic laboratory tests. Then a decision is made on the further procedure, typical for the diagnosis of cardiac arrhythmias, which most often includes: ECG, echocardiography, long-term Holter ECG recording, sometimes an exercise test, as well as non-invasive and invasive diagnostic pacing. The diagnostic procedure must be planned in detail by the doctor.
- In the case of a seizure block, is there a situation where nothing happens during the EKG or Holter? Often, patients feel great during the examination, and then they just have seizures, be it heart block, tachycardia or bradycardia.
Of course. This is the best definition of arrhythmia attacks and I must say that these are often diagnostically very difficult cases. Of course, very frequent ECG tests or Holter recordings may be recommended, but you may not capture this one and only moment when a block occurs. And the patient continues to complain of dizziness or fainting and expects help.
- What is the way out of this situation?
An implantable arrhythmia recorder is a very valuable diagnostic method in such patients. It is a small device the size of an elongated capsule that can be implanted under the skin of the chest almost in the form of an injection. Such a recorder can track and record the heart rhythm for several years; You can also remotely connect to it at any time and check its records. Unfortunately, this is not yet a device reimbursed by the National He alth Fund, which is a pity. This would make it possible to diagnose not only block but various other arrhythmias in many patients in need. Services are becoming a fairly common methodtelemedicine, allowing for remote ECG assessment by specialized centers. There are also more and more innovative technologies for monitoring the heart rhythm, such as applications in smartphones or t-shirts with built-in electrodes and microprocessors.
- Having a diagnosis, what are the treatment options for a heart block?
It can be said in general that there are no effective drugs for heart conduction disorders, as long as the cause is not a reversible disease that can be treated causally. If we recognize higher degrees of block: second and especially third degree block, it may be necessary to implant a pacemaker. The types of pacemakers are different and it is a task for us - specialists to match the most appropriate type of device to the patient's needs. In recent years, the so-called wireless pacemakers - small capsules implanted inside the heart, which are an autonomous electrode for stimulation, a microprocessor and a battery at the same time. These devices are still implanted in very rare and strictly defined cases, when the use of an ordinary pacemaker is impossible or is associated with risks, but in a few dozen years they will become the standard. Atrioventricular blocks are the starting point for such pacemakers. There are already several centers performing these procedures in Poland, including the Institute of Cardiology in Warsaw. It is also worth mentioning that in the case of patients with severe forms of block, but we cannot immediately implant a pacemaker or predict that we are dealing with a reversible disease - we can use temporary stimulation. That is, insert a thin electrode into the heart through a vein or stick two gel electrodes on the chest, and use an external pacemaker to stimulate the heart for some time, if necessary.
- How often are pacemakers implanted for heart blocks?
Poland is one of the most advanced countries in Europe when it comes to the availability of treatment with implantable cardiac electrotherapy devices, including pacemakers. Anyone who requires a pacemaker can be sure that this treatment will be provided quickly. Annually, we implant approximately 30,000 pacemakers in Poland, of which approximately one third are procedures resulting from the diagnosis of atrioventricular block. Hence, it is easy to calculate that for one million inhabitants of our country, about 250 people annually require pacemaker protection because of the atrioventricular block.
- How many patients have heart blocks? There are somestatistics?
Atrioventricular block can be a harmless find on the EKG, it can appear as a physiological phenomenon in young people, especially in sports, and it may also require treatment with a pacemaker. It can be assumed that we diagnose higher degrees of block annually in several hundred people per million and in these people we consider implantation of a pacemaker. The number of people with various forms of AV block is difficult to accurately estimate, but it is probably several times greater.
- And finally - what should patients pay attention to before diagnosing a heart block?
Everyone, especially the elderly, should pay attention to the symptoms that I mentioned earlier. Any fainting, dizziness or weakness should cause anxiety. It is worth going to the clinic then, telling the doctor about your ailments. At least an ECG test will be performed then and, if it turns out to be appropriate, further diagnostics will be recommended. Loss of consciousness is always dangerous and then of course you have to call an ambulance. Higher degree AV block is usually an indication for a pacemaker.
- Exactly, and patients with diagnosed disease and implanted pacemakers should watch out for?
These are modern electronic devices, but only devices. You should take care of your he alth, also take care of the area where the pacemaker is located - avoid strenuous hand movements on the side of the pacemaker and do not overload it. You must follow the recommendations of cardiologists, attend regular check-ups and inform the staff who care for patients about any disturbing symptom. In particular, one should react when symptoms similar or the same as before implantation reappear ( although they may not always be related to the same disease). Since the stimulator is an artificial implant - a foreign body, we should also pay attention to the sudden increase in temperature, chills, disturbing weakness, as well as the appearance of the skin over the place where the device was implanted. A blue, red, or swollen area may suggest inflammation and should also be consulted with your he althcare professional urgently.
The text was written on the occasion of the New Frontiers in Interventional Cardiology (NFIC) workshop.