Palpitations are a disorder, characterized by the perception of the heartbeat, which may be due to the acceleration or irregularity of the heart rhythm.
In fact, there is talk of palpitation both in the case of a physiological (or normal) increase in heart rate (also called “sinus tachycardia”), which can be induced by physical effort and emotion, and in the event of irregular heart rhythm, called “arrhythmias”.
The arrhythmias causing palpitations can be of various origins, both supraventricular (or atrial), and ventricular, and can be isolated, called “extrasystoles” (felt as a “failure to beat”) or, if prolonged, due to supraventricular paroxysmal tachycardias or atrial fibrillation, or in rare more severe cases, ventricular tachycardias.
WHAT ARE THE CAUSES OF PALPITATIONS?
The causes of palpitations can be of a nervous nature (anxiety, stress), or be due to intoxications (in particular inhalation of fumes or carbon monoxide), or to non-cardiac disorders (in particular gastro-esophageal, pulmonary, allergic crisis, anemia or thyroid diseases), or to cardiac causes, in particular ischemic heart disease, ventricular hypertrophy, heart failure, heart valve disease, and electrical heart disease.
The clinical features that suggest a cardiac origin of palpitations are as follows:
Known electrical heart disease (e.g. Wolff-parkinson-White syndrome, Brugada syndrome, Long QT syndrome)
History of previous arrhythmias (e.g. paroxysmal atrial fibrillation)
Family history of sudden death
Old age (or very young)
Palpitations can be associated with real pain in the thoracic site (precordialgia or angina) and in this case they direct the diagnosis towards problems related to the presence of cardiac ischemia (i.e. a spraying defect of the heart muscle due to the presence of stenosis (or narrowing ) of the heart arteries (called coronaries).
Palpitations can precede an episode of syncope (or loss of consciousness) and also in this case it is important to report it, as this symptom directs the diagnosis of the syncopal episode as being due to the presence of cardiac arrhythmias.
HOW IS DIAGNOSIS CARRIED OUT WHEN THERE ARE PALPITATIONS?
The first choice examination for the diagnosis of palpitations is the Holter dynamic ECG, preferably not only 24 hours, but prolonged, that is, recording the ECG trace for the duration of at least 7 days up to a maximum of 30 days, depending on the frequency of symptoms.
Example of paroxysmal supraventricular tachycardia recorded during prolonged Holter during palpitations
Furthermore, systems for recording short traces in conjunction with symptoms have also recently been proposed, directly via smartphone or i-watch, which also allow you to send the track directly to your doctor (system called “cardiotelephone”).
Then there are recording systems that are implanted subcutaneously that allow the recording of the heart rhythm up to 2-3 years, and regularly send the tracks through the remote monitoring system.
Again, another test often used in case of palpitations is the stress test, to verify the onset of any heart rhythm disturbances during exercise. In some cases, an electrophysiological study or a provocative study with drugs (ajmaline or isoproterenol) may be needed to complete the diagnosis.
It will be the duty of the arrhythmologist in case of palpitations to choose the most suitable system according to the case to make the diagnosis of the heart rhythm disorder, and then monitor over time the effectiveness of the different treatments (antiarrhythmic drugs or transcatheter ablation).
In addition to recording the heart rhythm, different morphological tests (echocardiogram, cardiac magnetic resonance, coronary angio-CT, or coronary angiography) are also necessary, to establish the presence of any cardiac or coronary artery disease.
WHAT TO DO IN CASE OF PALPITATIONS?
In case of palpitations, both in case of tachycardia and extrasystoles, it is good to stop any activity in which you are involved and try to relax to return the heartbeats to normal. A good practice is to lie down whenever possible and try to breathe deeply.
In the event that palpitations lasts for a long time (over an hour) or are associated with a feeling of fainting, or it is believed that there is a risk of anaphylactic shock, carbon intoxication, or pulmonary or cardiovascular diseases (see list of associated diseases) it is good to contact the Emergency Department. In other cases, consult your doctor as soon as possible.
Bibliography
Locati ET. New directions for ambulatory monitoring following 2017 HRS-ISHNE expert consensus. J Electrocardiol. 2017 Nov – Dec;50(6):828-832. doi: 10.1016/j.jelectrocard.2017.08.009. Epub 2017 Aug 12. PubMed PMID: 28928046.
Locati ET, Moya A, Oliveira M, Tanner H, Willems R, Lunati M, Brignole M. External prolonged electrocardiogram monitoring in unexplained syncope and palpitations: results of the SYNARR-Flash study. Europace. 2016 Aug;18(8):1265-72. doi: 10.1093/europace/euv311. Epub 2015 Oct 29. PubMed PMID: 26519025; PubMed Central PMCID: PMC4974630.
Rosano GM, Rillo M, Leonardo F, Pappone C, Chierchia SL. Palpitations: what is the mechanism, and when should we treat them? Int J Fertil Womens Med. 1997 Mar-Apr;42(2):94-100.
Brugada syndrome (BrS) is a genetic heart disease that carries an increased risk of sudden death.
The disease typically occurs during adulthood, on average around 40 years of age, and is estimated to be responsible for at least 4% of all sudden deaths, among which at least 20% of the deaths are of patients with a structurally normal heart.
Most diagnoses of BrS occur in young adults, often male, following the sudden death of a family member or with the occurrence of symptoms, such as syncope or cardiac arrest. The BrS has a characteristic electrocardiographic framework, represented by a typical over-leveling of the ST segment in the right precordial electrocardiographic leads (from V1 to V3), called Brugada pattern type 1. In cases where the electrocardiographic panel is suspected, but not diagnostic (Brugada pattern type 2 or 3), to confirm or exclude the diagnosis it may be necessary to carry out a test with class I antiarrhythmic drugs (e.g. ajmaline or flecainide), which unmask the diagnostic (type 1) Brugada pattern.
BrS patients generally have a structurally normal heart, although magnetic resonance imaging showed mild structural abnormalities of the right ventricle in a subset of patients.
This disease seems to be linked to a malfunction of one or more ion channels, which are structures that allow the transit of these ions (sodium, potassium, magnesium and calcium) through the cell surface. The first genetic alteration identified in BrS was that of the SCN5A gene that codes for the sodium channel. Subsequently, numerous and further genetic anomalies have been associated with BrS, with more than 300 mutations described.
Fig. 1
WHAT IS THE PREVALENCE OF BRUGADA SYNDROME?
Since its first description, BrS has been of great interest, both for its high incidence in some parts of the world and because it is associated with an increased risk of sudden cardiac death, particularly in males in the third and fourth decade of life.
In fact, over the past few years, there has been a dramatic increase in the number of reported cases and scientific publications on the subject. A first Consensus Conference held in 2002 defined the diagnostic criteria for the syndrome. A second Consensus Conference in 2005 focused on risk stratification and therapies.
The prevalence of Brugada syndrome in the general population is estimated to be around 5:10,000 individuals (or approximately 0.05%). The disease is presumably widespread worldwide, with a similar incidence in Europe and the United States, tending to be even higher in Asian countries (Figure 1). The frequency is lower in western countries and higher in Southeast Asia, especially in Thailand and the Philippines, where Brugada syndrome is considered to be the main cause of sudden death in young individuals. In these countries, the syndrome is often referred to as SUNDS (sudden unexplained nocturnal death syndrome).
The disease is probably the leading cause of death in patients under 40 years of age. In any case, the pathology seems to be underestimated, due to the difficulties of diagnosis, due to the fact that the first symptom is often sudden death, and that the characteristic electrocardiographic pattern is highly variable over time.
Fig.2
AT WHAT AGE DOES BRUGADA SYNDOME NORMALLY AFFECT PEOPLE?
Brugada syndrome typically occurs in youth and adulthood, generally after adolescence, with an average age at the presentation of symptoms of around 40 years (41 ± 15 years in our case history). Typically men show the disease more frequently than women (with a ratio of about 5:1 in our case history). More rarely, BrS occurs in children, and could explain some cases of sudden infant death syndrome (SIDS).
WHAT ARE THE GENETIC CHARACTERISTICS OF BRUGADA SYNDROME?
BrS is a genetic disease with predominantly autosomal dominant transmission. Therefore, the probability of transmitting the pathology is 50% with each pregnancy. The genetic investigation, performed starting from a simple blood sample, is important not only for the clinical management of the patient, but above all for the identification of any other affected family members.
According to literature data, in patients in whom a gene mutation is discovered, in about 50% of cases a mutation is observed in the SCN5A gene, a gene involved in the function of the sodium channel, while the remaining cases have anomalies in other genes.
In the case of probands with a suspecision of BrS, in our center, genetic screening is carried out on a blood sample using the NSG (Next Generation Sequencing) method on a panel of 25 genes (ABCC9, AKAP9, CACNA1C, CACNA2D1, CACNB2, DSC, DSG2, GPD1L, HCN4, KCND2, KCND3, KCNE3, KCNE5, KCNH2, KCNJ8, MOG1, PKP2, RANGRF, SCN5A, SCN10A, SCN1B, SCN2B, SCN3B, SEMA3A, TRPM4).
Brugada syndrome is one of the main focuses of our center’s clinical and research activity. To date, over 300 families with BrS have been studied in our center, for a total of more than 1000 individuals.
WHY PERFORM FAMILY SCREENING IN CASE OF SUSPECTED BRUGADA SYNDROME?
Given the genetic origin of the syndrome, investigating family history is very important. BrS patients may have a positive family history of sudden death at a young age (i.e. less than 50 years of age) from unknown causes. Other aspects that deserve further study are the possible presence of family members diagnosed with epilepsy or a history of repeated abortions or unexplained infant deaths in the family.
In the event that, during family screening, affected family members are identified, there is the need to perform further investigations for the stratification of any arrhythmic risk.
WHAT ARE THE ELECTROCARDIOGRAPHIC SIGNS OF BRUGADA SYNDROME?
The electrocardiogram (ECG) of the affected patient can vary a lot over time, even within the same day, passing from moments in which the tracing is substantially normal to others in which it becomes frankly pathological.
The disease can have three different ECG pictures (also called ECG “phenotypes”), of which only Type 1 is actually diagnostic for Brugada syndrome (Figure 2).
Type 1 is the so-called “elevation of the ST coved type”, with an elevation of the J point of at least 2 mm (with “curtain” morphology) and a gradual descent of the ST segment and a negative T wave in V1 and V2.
Type 2 has the so-called “saddle-back pattern” (“saddle aspect”), with an elevation of the J point of at least 2 mm and an elevation of the ST section of at least 1 mm with a positive or biphasic T wave.
Type 3 it has the so-called “saddle-back pattern” with an elevation of the J point of less than 2 mm, an elevation of the ST section of less than 1 mm and a positive T wave. Type 3 is very unspecific since it is also present in healthy subjects, in particular in athletes and in young subjects.
In doubtful cases (spontaneous Brugada type 2 or 3 pattern), the execution of a provocative pharmacological test (Ajmaline) is recommended, to unmask the type 1 pattern and therefore diagnose BrS.
Fig. 4
The presence of anomalies in the peripheral or lateral branches (particularly aVR) has also recently been reported as an additional risk factor.
Other conduction disturbances have also been described in Brugada syndrome such as:
atrioventricular block (AVB) (conduction delay has been reported to be sub-Hissian and that the H-V interval is prolonged in most patients);
intraventricular conduction disorders (cases of isolated right bundle branch block or associated with left anterior hemiblock have been reported).
HOW SHOULD THE ELECTRODES BE POSITIONED TO HIGHLIGHT THE BRUGADA PATTERN IN THE ELECTROCARDIOGRAM?
To identify the possible presence of spontaneous Type 1 patterns, it may be necessary to position the precordial leads in the 2nd and 3rd intercostal space instead of in the classic 4th intercostal space.
This allows to increase the possibility of identifying the typical electrocardiographic anomaly and therefore to diagnose BrS. This happens because the Brugada phenomenon, in basal conditions, occurs in a very limited portion of the right ventricular region, whose potentials are detected only if the electrodes are placed practically above the affected region.
Fig. 5
WHAT ARE THE SYMPTOMS OF BRUGADA SYNDROME?
Characteristic of the BrS is the extreme variability of the clinical presentation.
Unfortunately, in a considerable percentage of patients, the first clinical manifestation of the disease is sudden death, due to fatal ventricular arrhythmias. The latter catastrophic event underlines the difficulty of managing the disease in predicting which individuals will be at greatest risk, since before this event, the vast majority of patients do not present with any warning symptoms.
Affected patients may also be totally asymptomatic or exhibit symptoms due to cardiac arrhythmias, with episodes of syncope (i.e. loss of consciousness), episodes of palpitations or heart rate. Sometimes patients may have seizures and symptoms that can be confused with epilepsy. Symptoms often occur at rest, in the recovery phase from exercise or during night sleep.
HOW IS THE DIAGNOSIS OF BRUGADA SYNDROME CARRIED OUT?
A timely diagnosis is crucial for this syndrome, as the affected patient may be at risk of potentially fatal arrhythmias. When the suspicion of Brugada syndrome has been raised, family history and the electrocardiographic tracing must be obtained, and other cardiological tests performed, including echocardiogram (to exclude the presence of any heart disease).
Confirmation of a Brugada syndrome diagnosis is possible with the presence of a spontaneous type 1 pattern.
However, in most cases, the ECG pattern is suspicious of BrS, but not diagnostic (type 2 or 3 pattern), and it may be necessary to resort to a pharmacological test with Ajmaline, which in predisposed subjects induces the appearance of the Brugada pattern type 1, and therefore allows to exclude or confirm the diagnosis of Brugada syndrome.
In the case of a positive pharmacological test, an endocavitary electrophysiological study (EES) may be necessary, in order to verify the possible vulnerability of a patient to potentially malignant ventricular arrhythmias.
WHAT IS THE PHARMACOLOGICAL TEST FOR BRUGADA SYNDROME?
The provocative pharmacological test “Ajmaline test“, consists of the administration of a drug blocking the sodium channels (ajmaline), which unmasks the Brugada type 1 pattern in cases where the electrocardiographic anomalies are not already diagnostic for BrS.
In fact, this provocative test is useful in patients with ECG patterns type 2 and 3. In these cases, the test is positive (diagnostic) when the drug induces a transformation of the ECG pattern into type 1. In patients with spontaneous type 1 patterns, the test is not recommended.
The provocative pharmacological test is not intended to cause arrhythmias, but in particularly high-risk cases, ventricular arrhythmias may arise. Therefore, the provocative pharmacological test is carried out in a suitable environment and in the presence of personnel trained to deal with the onset of arrhythmias.
FOR WHAT IS THE ENDOCAVITARY ELECTROPHYSIOLOGICAL STUDY (EES)?
The endocavitary electrophysiological study (EES), through programmed ventricular stimulation, is used to verify the inducibility of ventricular arrhythmias, i.e. the predisposition of a certain patient to develop potentially fatal arrhythmias.
Since patients with Brugada syndrome are at risk of sudden death, EES is carried out in subjects suffering from the syndrome in order to be able to recognize patients at risk of spontaneously developing ventricular arrhythmias.
At present, the EES is, however, one of the few useful tests available for an adequate risk stratification in the individual patient, and is used to guide the choice of the most appropriate therapeutic strategy.
Fig. 7
WHICH DRUGS ARE TO BE AVOIDED IN BRUGADA SYNDROME?
In particular, patients should avoid the administration of antiarrhythmic drugs blocking the sodium channels (specifically Ajmaline and Flecainide or Propafenone, etc.), which can also be used as provocative pharmacological tests to confirm the diagnosis of the disease.
It should be noted that, in some patients, the diagnosis of Brugada syndrome is carried out occasionally following the administration of flecainide or propafenone for atrial arrhythmias, in particular for atrial fibrillation. Therefore, in general, it is always recommended to carry out a 12-lead ECG before and after starting therapy with class 1 antiarrhythmic drugs.
ARE DRUGS DANGEROUS FOR PEOPLE WITH BRUGADA SYNDROME?
In patients with Brugada syndrome, it is important to avoid alcohol, smoking, and drug abuse (in particular cocaine), which can induce the onset of potentially fatal ventricular arrhythmias.
WHAT ARE THE MOST FREQUENT ARRHYTHMIAS IN BRUGADA SYNDROME?
The sudden death linked to the onset of malignant ventricular arrhythmias can unfortunately represent the first clinical manifestation of Brugada syndrome. Among these arrhythmias, the most frequent is polymorphic ventricular tachycardia, which degenerates into ventricular fibrillation and therefore causes cardiac arrest. These ventricular arrhythmias can be triggered by ventricular ectopic beats, i.e. ventricular extrasystoles.
The wide spectrum of anomalies related to Brugada syndrome include, in a non-negligible percentage, bradyarrhythmias, such as sinus-atrial blocks and paroxysmal atrio-ventricular blocks, which can, in turn, increase the risk of sudden death.
In addition, BrS patients may also experience a range of other atrial arrhythmias, such as atrial fibrillation and paroxysmal supraventricular tachycardias (SVT), which can affect quality of life. These arrhythmias, although non-malignant, can represent warning signs of a genetic disease, especially if they occur at a young age in people without structural heart disease. Therefore, in specific cases, an accurate specialist assessment is necessary in order to exclude the possibility of BrS.
WHAT ARE THE TREATMENTS RECOMMENDED FOR BRUGADA SYNDROME?
Once the diagnosis of BrS is made, the therapeutic approach depends on the patient’s level of risk. Brugada syndrome does not present with a definite clinical progression, and therefore a patient may experience new clinical elements indicative of a possible change in the level of risk. Therefore, it is appropriate to carry out checks every six months.
Currently the therapeutic options available for Brugada syndrome are essentially of three types:
Implantation of cardiac defibrillator (ICD, intracavitary or subcutaneous) or implantable cardiac monitors (subcutaneous ICM or loop recorder)
Transcatheter epicardial ablation of the arrhythmic substrate
Drug therapy with specific antiarrhythmic drugs (Quinidine)
In our center, we have developed an approach based on the clinical characteristics of each individual, born from our wide and long clinical experience with thousands of cases followed with a long follow-up.
Fig. 8
WHEN TO USE THE CARDIAC DEFIBRILLATOR (ICD) AND CARDIAC MONITOR (ICM) SYSTEM IN BRUGADA SYNDROME?
ICD is the only therapy with proven efficacy in preventing sudden arrhythmic cardiac death.
The implantation of a defibrillator is necessary in the event of a finding of BrS that presents with high risk characteristics. The risk stratification is based on an evaluation of a series of objective clinical parameters (electrocardiographic, non-invasive, clinical parameters deriving from the electrophysiological study) together with the presence of symptoms attributable to potentially lethal arrhythmias.
Given the possible presence of supraventricular arrhythmias or disturbances of the condition, the use of the intracavitary defibrillator is generally preferred, even if in younger subjects, or in patients who have had problems related to the intracavitary defibrillator you can opt for the implantation of a subcutaneous defibrillator.
An approach that is based on multiple parameters is always necessary in order to optimize the most appropriate therapeutic choices, based on the clinical needs of each individual patient. In fact, each of these choices is based on the assessment of the risk of developing potentially fatal arrhythmias, and this is carried out both in the adult and pediatric population. In the latter context, in the most serious and most risky cases it is possible to implant a defibrillator. Instead, in conditions of apparently lower risk, it is possible to offer the implantation of a cardiac monitor under the skin (implantable cardiac monitor ICM or better known as loop recorder) that constantly records the electrocardiogram. The latter offers the possibility of monitoring patients for many years in order to document any arrhythmias that may change the assessment of the arrhythmic risk over time, and therefore modify the therapeutic strategy if indicated.
Each of these devices, ICD or ICM, are available in association with remote monitoring technology, better known as home monitoring. This technology allows you to monitor the operation of these devices remotely while the patient is at home. A modem connected wirelessly records the information of the implanted device and sends it to a secure website, which is only accessible to doctors. In this way, doctors can check not only the correct functioning of the device, but also the onset of any arrhythmias, so that they can intervene promptly with the most appropriate therapeutic strategies.
WHEN TO PERFORM EPICARDIAL ABLATION OF THE ARRHYTHMIC SUBSTRATE IN BRUGADA SYNDROME?
In 2015, our team led by Prof. Pappone demonstrated that the arrhythmogenic substrate of Brugada syndrome is preferentially located in the epicardial region of the outflow tract and the anterior wall of the right ventricle. These areas are characterized by the presence of abnormal electrical potentials that can give rise to those arrhythmias capable of triggering cardiac arrest in patients with BrS.
Once the epicardial arrhythmogenic substrate has been precisely identified, our team has always shown that epicardial ablation by radio frequency is able to eliminate all electrical anomalies, and this leads to the immediate disappearance of the electrocardiographic pattern of Brugada syndrome and the absence of ventricular arrhythmias in follow-up.
This procedure was proposed and developed in our center, which is the most experienced center in the world for this type of intervention.
Currently more than 600 patients with Brugada syndrome have undergone ablation, with an extremely low incidence of perioperative complications.
The ablation strategy proposed by our group can be applied safely and effectively to a greater number of patients with Brugada syndrome considered at risk.
This experience is the largest case history in the world of patients with BrS treated by ablation, and this establishes the first step for a new strategy for the treatment of BrS available to affected patients.
WHEN TO CARRY OUT PHARMACOLOGICAL THERAPY WITH QUINIDINE IN BRUGADA SYNDROME?
Drug therapy with quinidine, although effective in general terms, is burdened by numerous side effects that prevent its prolonged and continuous use. This means that this therapy cannot be in any way a substitute for the aforementioned therapies, and is therefore reserved only for those who continue to have arrhythmic recurrences. However, it has been widely demonstrated that the latter category of patients benefits better from ablative therapy compared to chronic drug therapy.
I HAVE BRUGADA SYNDROME. ARE THERE ANY SPECIAL PRECAUTIONS I NEED TO TAKE IF I HAVE A COVID-19 INFECTION?
The link between hyperpyrexia (fever) and the onset of a type 1 Brugada syndrome pattern and cardiac arrhythmias has been known for years. Therefore, patients with Brugada syndrome (both with spontaneous and drug-inducible type 1 patterns) are particularly at risk of fatal arrhythmias if their body temperature exceeds 37.5° C. These patients must therefore treat fever aggressively with the use of paracetamol and warm / cold sponging.
The increase in body temperature could, in fact, alter the function of the cardiac ion channels, leading to potentially fatal arrhythmias.
In the case of COVID-19 infection, other factors besides fever could favor the genesis of cardiac arrhythmias, including stress, the use of potentially pro-arrhythmic drugs, and imbalances of blood electrolytes.
Therefore, in patients suffering from Brugada Syndrome with particularly high temperatures (above 38.5° C despite therapy with antipyretic drugs such as tachipirina), hospitalization and, in some cases, intensive care, is warranted to monitor the ECG.
I HAVE BRUGADA SYNDROME. CAN I GET VACCINATED AGAINST COVID-19 AND ARE THERE ANY SPECIAL PRECAUTIONS I NEED TO TAKE IF I AM VACCINATED AGAINST COVID-19?
There is no specific data concerning the use of the COVID-19 vaccine in patients with Brugada syndrome. Given the risks associated with COVID-19 infection, particularly in patients at risk of cardiac arrhythmias, we generally recommend patients with Brugada syndrome, even in young people, to undergo prophylactic vaccination.
As for the type of vaccine, given that many of the affected patients are young, it is still preferable to use anti m-RNA vaccines. In any case, we recommend the use of antipyretic drugs in the event of a post-vaccination rise in body temperature (with tachipirina in case of fever greater than 37.5° C).
In the case of Brugada syndrome patients with specific comorbidities (for example oncological, neurological, autoimmune or hematological, acute or chronic diseases), the decision to carry out the COVID-19 vaccination must be made on a case-by-case basis, after a careful individual evaluation of the risk-benefit ratio.
Long QT Syndrome (LQTS) is a genetically based cardiac pathology characterized by a high risk of ventricular cardiac arrhythmias, which can cause syncope (loss of consciousness), cardiac arrest, and sudden death. The disease is characterized by the prolongation of the QT interval, measured on the surface electrocardiogram, and by morphological anomalies of the T wave. LQTS manifests usually during childhood, but in some cases it may begin even after puberty. The severity of the disease is highly variable and, at least in part, dependent on the type of gene or mutation involved.
LQTS was first recognized in 1957 in Norway by Jervell and Lange-Nielsen, who described the subtype of the syndrome associated with neurological deafness, characterized by sudden family death with recessive inheritance. In the early 1960’s, the subtype without congenital deafness, characterized by prolongation of the QT interval, with syncope history and sudden death with autosomal dominant inheritance, was described independently by both an Italian pediatrician and an Irish pediatrician, resulting in this disease being called Romano-Ward syndrome. In 1979, the Prospective International Registry for Long QT Syndrome was established, which enabled the evaluation of many families affected by the disease worldwide, enabling them to obtain fundamental information on the clinical history of the disease, its therapy, and its genetic basis (Moss AJ, Circulation 1991).
What are the causes of Long QT Syndrome?
Today we know that LQTS is caused by mutations in genes that control potassium and sodium currents. Currently at least 15 involved genes have been identified, of which the three most important are: 1) KCNQ1, which results in LQT1, 2) KCNH2 (HERG), which results in LQT2, and 3) SCN5A, which results in LQT3. The anomalies in the potassium and / or sodium channels result in a ventricular repolarization defect, which is visualized on the ECG trace as prolongation of the QT interval and as morphological anomalies of ventricular repolarization, which favor the genesis of particular polymorphic ventricular tachycardias, called torsades-de-pointes, that can resolve spontaneously or degenerate into ventricular fibrillation.
What is the incidence of Long QT Syndrome?
The prevalence of LQTS is estimated at 1:2,500 live births, with a reasonable variability in the different geographical areas. Most people with this condition develop symptoms before age 40. The age of onset of symptoms appears to differ based upon gender and the type of genetic variant. LQTS is a relatively common cause of sudden death, along with Brugada Syndrome and arrhythmogenic right ventricular dysplasia (ARVD), and in particular it could be responsible for some cases of Sudden Infant Death Syndrome (SIDS).
What are the symptoms of Long QT Syndrome?
Patients, mostly children and adolescents, present to the clinic following unexplained fainting (syncope), a family history of sudden death, or referral by a physician after a physical exam for participation in sports, during which the prolongation of the QT interval was observed.
The diagnosis can also occur in adulthood, particularly in female patients in post-partum or menopause, or following taking drugs that prolong the QT interval.
The clinical manifestations of LQTS are precisely linked to the appearance of episodes of polymorphic ventricular tachycardia called “Torsades de pointes”. The duration of the episodes determines the symptoms, ranging from syncope (i.e. transient loss of consciousness) to cardiac arrest to sudden death, when Torsades de Pointes degenerate into ventricular fibrillation.
Often the syncopal episodes of LQTS are mistaken for convulsive or epileptic seizures, thus delaying the diagnosis and the correct therapy of the disease. Collecting the patient’s family history, including episodes of fainting or convulsions, diagnosis of epilepsy or cases of sudden death at a young age, help to direct the diagnosis.
What are the electrocardiographic features of Long QT Syndrome?
The diagnosis of LQTS is made mainly by the electrocardiographic tracing, using either 12-derivation ECG or dynamic Holter ECG, with the detection of the prolongation of the QT interval corrected for the heart rate according to the Bazett formula.
In patients with a history of syncope, the diagnosis of long QT is made when the duration of the corrected QT interval is greater than 460 msec. In the absence of syncope or family history of LQTS or documented arrhythmias, the clinical diagnosis of LQTS may require the presence of a corrected QT interval greater than or equal to 480 msec.
It should be noted that the prolongation of the QT interval may not be present in the resting ECG trace, but may be documented during dynamic ECG Holter monitoring.
For the correction of the QT interval for heart rate, in addition to the Bazett formula, there is also the Fredericia formula, particularly used in pediatric patients, and in particular in the analysis of the QT interval during Holter recordings, since the Bazett formula can overestimate the duration of the QT interval in case of marked tachycardia.
Nella LQTS, oltre che la durata dell’intervallo QT, è alterata anche la morfologia dell’onda T, con la comparsa di particolari anomalie, dette incisure o notches. La morfologia dell’ECG è stato descritto essere differente nelle diverse varianti genetiche (Moss, Circulation 1991).
What are the genetic characteristics of Long QT Syndrome?
Long QT Syndrome is caused by mutations in genes that control potassium and sodium currents. Currently at least 15 involved genes have been identified, of which the three most important are: 1) KCNQ1, which results in LQT1, 2) KCNH2 (HERG), which results in LQT2, and 3) SCN5A, which results in LQT3. In familial forms, pathogenic variants of these genes are identified in a percentage of patients ranging from 60% to 75% of cases. Other genetic variants are identified in very low percentages (about 1-2% of cases), while in about 20% of cases no known genetic mutations are identified.
Genotype
Gene
Chromosome
Incidence
Current
LQT1
KCNQ1
11
30-35%
Iks (reduced)
LQT2
KCNH2
7
25-30%
Ikr (reduced)
LQT3
SCN5A
3
5-10%
Ina (increased)
Genetic analysis is therefore fundamental in the diagnosis of LQTS, and has become an essential component for clinical management. The identification of the gene that causes the disease makes it possible to carry out a family screening, to quickly identify the family members carrying the mutation, thus allowing the prevention of sudden death in the whole family.
However, numerous recent studies indicate that LQTS cannot always be explained by a single genetic mutation, but seems to follow a more complex genetic model, where common genetic polymorphisms could have a specific effect on disease expression (modifier genes).
Finally, many studies are already in place to develop gene-specific treatments in LQTS, while a gene-specific prevention of the risk of events is already possible, since the triggers of the events are different in the various genetic forms.
In our center, the analysis of long QT genes is carried out by means of a “Next Generation Sequencing” (NGS) platform that enables the simultaneous study of more patients for mutations in different genes. All variants identified by NGS are always confirmed with another sequencing method, Sanger sequencing.
What are the triggers of arrhythmias in Long QT Syndrome?
There is a close correlation between the factors that trigger arrhythmias and the genetic variant of which the patient is a carrier. Therefore, the prevention of the risk of arrhythmias is different depending on the genetic form.
In LQT1 patients, the largest genetic subgroup, most life-threatening cardiac events occur during exercise, particularly during swimming. Patients with LQT1 are also sensitive to potassium depletion.
LQT2 patients are particularly sensitive to emotions and sudden noises, such as the ringing of the telephone or that of the alarm clock, and moreover, the LQT2 females seem to be at higher risk in the postpartum period. Patients with LQT2 are also the most exposed to the risk of proarrhythmic effects of some drugs, which act as blockers of the Ikr current, and of potassium depletion.
LQT3 patients have more frequent events during resting or sleeping conditions. The pivotal therapy is β-blocker therapy, which has shown efficacy in reducing mortality in the LQTS patient population.
What are the therapies of Long QT Syndrome?
Patients with LQTS should always avoid drugs that prolong the QT interval (www.crediblemeds.org). In patients with LQTS, it is important to correct electrolyte disorders (hypokalemia, hypomagnesaemia, hypocalcemia) that may occur in the case of metabolic or gastrointestinal illness problems, and in the case of diuretic therapies.
First choice drug therapy is based on the use of full-dose beta-blockers. Some studies show that, in LQTS, not all β-blockers have equal efficacy and that the most effective beta-blockers are propranolol and nadolol.
The use of beta-blockers is recommended in all subjects with a clinical diagnosis of LQTS, even if asymptomatic, given that beta-blockers reduce mortality from 60% to less than 2%.
The implantable cardioverter-defibrillator (ICD) is recommended in patients with previous cardiac arrest. ICD implantation is also recommended when a patient receiving full-dose beta-blockers has a new syncope episode. The ICD is also recommended in asymptomatic patients with a very prolonged QT (QTc> 500 msec), carrying a pathogenic mutation in one of the three main genes.
In patients with an ICD who have an arrhythmic recurrence, or in patients with contraindications to beta-blockers or ICDs, the execution of left sympathetic cardiac denervation can be considered.
Sodium channel blockers (Mexiletine or Flecainide or Ranolazine) can be considered as additive therapy to shorten the QT interval in LQT3 patients with QTc greater than 500 msec.
Essential bibliography
Moss AJ, Schwartz PJ, Crampton RS, Tzivoni D, Locati EH, MacCluer J, Hall WJ, Weitkamp L, Vincent GM, Garson A, Jr. and et al. The long QT syndrome. Prospective longitudinal study of 328 families. Circulation 1991; 84:1136-1144.
Priori, SG, Wilde AA, Horie M et al: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndrome. Heart rhythm 2013; 10: 287-294.
Moss AJ, Zareba W, Benhorin J, Locati EH, Hall WJ, Robinson JL, Schwartz PJ, Towbin JA, Vincent GM, Lehmann M, Keating MT, MacCluer JW, Timothy KW: ECG T wave patterns in genetically distinct forms of the hereditary long QT syndrome. Circulation 1995; 92: 2929-2934.
Schwartz PJ, Priori SG, Locati EH, Napolitano C, Cantu’ F, Towbin AJ, Keating MT, Hammoude H, Brown AM, Chen LK, Cotasky TJ: Long QT syndrome patients with mutations on the SCN5A and HERG genes have differential responses to Na+ channel blockade and to increase in heart rate. Implications for gene-specific therapy. Circulation 1995; 92: 3381-86.
Mizusawa Y, Horie M, Wilde AAM, Genetic and Clinical Advances in Congenital Long QT Syndrome., Circ J 2014; 78: 2827–2833.
Bring to the table win-win survival strategies to ensure proactive domination. At the end of the day, going forward, a new normal that has evolved from generation.
Atrial fibrillation (AF) is a very frequent arrhythmia, as it affects 1-2% of the population, and the chances of developing this condition increase with advancing age.
Under normal conditions, the heart contracts thanks to specialized cellular structures that generate electrical impulses and regulate their distribution in the heart itself. The electrical impulse originates in the atrial sinus node, located in the right atrium, propagates in the atria and reaches the atrio-ventricular node, which is the only way of electrical communication between the atria and ventricles; from here the impulse passes to the His bundle and to the intraventricular conduction system.
There is talk of atrial fibrillation when the electrical activation of the atria derives from the continuous and chaotic circulation of the impulse along the atrial walls: the atria no longer contract in a coordinated manner, but have a chaotic activity, called “fibrillation”.
How is atrial fibrillation defined?
Atrial fibrillation is a supraventricular arrhythmia, the electrocardiographic diagnosis of which is based on the following two elements:
absence of P waves
irregularities of R-R intervals
In atrial fibrillation, the activation of the atria is chaotic and continuously variable, so the P waves disappear and are replaced by small waves called f waves. The f waves are completely irregular, have continuous changes in morphology, voltage and intervals ff, have very high frequency (400-600 rpm) and last throughout the cardiac cycle (they are continuous) resulting in a jagged appearance of the isoelectric line (particularly visible in branches V1-V2).
In atrial fibrillation, a large number of atrial impulses reach the atrioventricular (AV) junction, but only a part of these then reaches the ventricle. The AV node performs a filter function: numerous impulses only partially penetrate the node and are blocked within it. This irregularity of AV conduction causes the R-R intervals to be variable. The number of atrial impulses that are conducted to the ventricles is defined as a ventricular response, which can be high (or tachycardia, when the number of impulses is greater than 100 impulses per minute) or low (bradycardia, when the number of impulses is less than 50 pulses per minute).
The continuous variation of ventricular cycles constitutes the cardinal element in the diagnosis of atrial fibrillation, so much so that when the arrhythmia occurs with constant R-R intervals, it is less unlikely that it is atrial fibrillation, but more likely that it is a supraventricular tachycardia.
What are the types of atrial fibrillation?
There are three different types of atrial fibrillation, essentially defined by duration:
Paroxysmal atrial fibrillation: form characterized by spontaneous interruption of arrhythmia, generally within 7 days, mostly within 24-48 hours;
Persistent atrial fibrillation: arrhythmia (regardless of its duration) does not stop spontaneously but only with therapeutic interventions (pharmacological or electrical cardioversion);
Permanent or chronic atrial fibrillation: form in which no attempts to stop the arrhythmia have been made or, if they have been made, have not been successful due to failure to restore the sinus rhythm, or for immediate recurrence, or in which further attempts at cardioversion are not indicated.
What is the prevalence of atrial fibrillation?
The prevalence of atrial fibrillation in the general population is reported to be around 1%, depending on the different studies. The prevalence appears relatively low in young subjects and progressively increases with advancing age. In the North American ATRIA study, the prevalence in the general population is 0.9%, but it is 0.1% in subjects < 55 years of age and 9% in subjects > 80 years of age. In the Framingham study, the prevalence is 0.5% in the 50-59 age group, 1.8% in the 60-69 age group, 4.8% in the 70-79 age group, and 8.8% in the 80-89 age group. About 70% of patients with atrial fibrillation are over 65 years old with a median age of 75 years. The prevalence appears slightly higher in men than in women in all age groups (1.1% versus 0.8%, in the ATRIA study).
According to data from the Istituto Superiore di Sanità, atrial fibrillation is currently the most frequently sustained arrhythmia in clinical practice in Italy, with a prevalence in the general population of 0.5-1%. It is possible to estimate that the number of patients suffering from atrial fibrillation in Italy are around 610,000 people (10% of the total population). The prevalence has gradually increased over time and is expected to further increase in the coming years, given the rapid aging of the population and the growing number of subjects over the age of 65.
What conditions predispose a person to atrial fibrillation?
As far as the etiopathogenesis, atrial fibrillation can be primary or secondary.
Primary, idiopathic, or isolated atrial fibrillation is not associated with organic heart disease or other clinical situations related to arrhythmia (bronchopneumopathy, hyperthyroidism, etc.). The prevalence of primary atrial fibrillation is variable (around 5%).
Secondary atrial fibrillation, on the other hand, is one in which a cause of arrhythmia or a condition that causes arrhythmia can be identified. Among the factors that predispose to atrial fibrillation, the main conditions are the following:
hypertension
heart valve diseases, especially mitral and aortic valves
The symptoms of atrial fibrillation are extremely variable from patient to patient, and can be from very marked to almost absent.
The most frequent symptoms, in decreasing order according to the ALFA study, are palpitations (54.1%), dyspnea (44.4%), fatigue (14.3%), syncope (10.4%) and chest pain (10.1%). Palpitations prevail in the paroxysmal form (79%), while dyspnea in the chronic and recent onset (46.8% and 58%, respectively).
In addition to symptomatic, atrial fibrillation can also be asymptomatic or silent, representing an occasional finding on standard ECG or dynamic ECG Holter in about 20% of cases.
What is silent atrial fibrillation?
Many patients, especially elderly patients, or patients with other pathologies and in multitherapy, can be completely asymptomatic, and in this case we speak of silent AF. In these patients, the detection of AF often occurs entirely occasionally, or in conjunction with hospitalization for an episode of heart failure, caused precisely by an unrecognized rapid atrial fibrillation. Silent atrial fibrillation is no less dangerous for this, but it is more difficult to diagnose, and more insidious, because even if asymptomatic in the initial stages, it can lead to important complications, such as heart failure, cryptogenic stroke, or, according to the most recent studies, cognitive disorders (like dementia).
What are the consequences and risks of atrial fibrillation?
The hemodynamic consequences and remodeling induced by atrial fibrillation translate, in clinical terms, into a reduction in the quality of life due to the appearance of important subjective disorders, in an increase in cardiovascular mortality, in a higher incidence of thromboembolic complications, and in the possible appearance of tachycardiomyopathy.
Quality of life is significantly reduced in subjects with atrial fibrillation compared to control subjects, with a lower score of 16% – 30% of all parameters commonly considered (general health status, physical functions, vitality, mental state, emotional functions, social role, physical pain).
If the heart rate is particularly high and the arrhythmia persists for weeks or months, the contractile force of the heart may progressively decrease and progress into heart failure.
Furthermore, in fibrillating atria (and in particular in their contractile appendages, called “auricles”) the blood tends to stagnate instead of being expelled from the normal contraction. The conditions are therefore created for the formation of clots (thrombi) which can migrate into the circulation as emboli.
Particularly dangerous are the emboli released from the left atrium because they can reach the cerebral circulation and cause serious damage, in particular thromboembolic stroke.
How is the diagnosis of atrial fibrillation made?
The diagnosis of atrial fibrillation itself is very simple, since an electrocardiographic trace, in particular the 12-lead ECG trace, is sufficient.
Examples of fibrillation detected by 12-lead ECG
The problem is the difficulty in catching the arrhythmia when it is present (for the short duration or for the total lack of the reference symptoms). Even in follow-up, the main obstacle is the difficulty of detecting with certainty the episodes of atrial fibrillation.
For this we use prolonged electrocardiographic recording systems called dynamic ECG Holter (which can last from 24 hours to several days, generally up to a maximum of 30 days).
Example of fibrillation detected by ECG Holter extended 30 days
Then there are small long-lasting recording systems that are inserted subcutaneously through a small incision, called the “implantable loop recorder” (or ILR). These systems can last up to three years and can also be interrogated through remote monitoring, i.e. directly from the patient’s home, without requiring patient access to the hospital.
Example of fibrillation identified by implantable Loop recorder
Recently, recording systems of short ECG traces are also available (generally about 30 sec, single channel) based on Smartphone technology, also through the iWatch system, which allow the patient to independently record a short ECG tracing, on which the system performs a first analysis and proposes a first diagnosis of the rhythm. The track can then be sent by email for verification by the Analysis Center: this service is called Cardiotelephone.
In addition to identifying atrial fibrillation with the electrocardiogram, a complete diagnostic framework is necessary to demonstrate or exclude cardiac or endocrine pathologies that cause or facilitate atrial fibrillation and require treatment.
What are the treatments for atrial fibrillation?
The treatment of a patient with atrial fibrillation requires knowledge of the aspects of arrhythmia presentation (paroxysmal, persistent, chronic), first event or recurrence, symptomatic or asymptomatic, and the basic clinical situation. Only later can decisions be made about whether or not an attempt should be made to restore the sinus rhythm, how to restore the sinus rhythm, and its subsequent maintenance.
Atrial fibrillation therapy is essentially based on these four aspects:
Heart rhythm control, i.e. the attempt to restore sinus rhythm and prevent AF recurrence, particularly in the case of paroxysmal and persistent AF, essentially through antiarrhythmic drugs and transcatheter ablation
Heart rate check (“rate control”), i.e. control of the frequency response, particularly in case of permanent atrial fibrillation, essentially through antiarrhythmic drugs, including beta-blocker drugs and digitalis.
At the first finding of atrial fibrillation, even if asymptomatic, the attempt to restore the sinus rhythm is indicated, providing it’s compatible with the patient’s age and the presence of co-pathologies. If the arrhythmia is of recent onset and in the absence of heart disease, the first therapeutic choice for the restoration of the sinus rhythm is antiarrhythmic drugs. In case of longer duration of the arrhythmia, or of heart disease, or of hemodynamic instability, the first therapeutic choice instead becomes the electrical cardioversion.
Regardless of the technique used for the restoration of the sinus rhythm, great attention must be paid to compliance with the protocols for the prevention of thromboembolic risk, in particular by evaluating the duration of the arrhythmia and any underlying heart disease.
After restoration of the sinus rhythm, in many cases no prophylaxis of recurrence is necessary (e.g. atrial fibrillation from correctable cause, or first episode of short duration and hemodynamically well tolerated). If, on the other hand, based on the clinical picture, prophylaxis is considered appropriate, the first therapeutic step is generally antiarrhythmic drugs, taken as needed or chronically.
In case of drug ineffectiveness or intolerance, or in case of recurrence, catheter ablation procedures may be considered as an alternative to chronic atrial fibrillation.
When is ablation of atrial fibrillation recommended?
In cases of paroxysmal or persistent AF, and in case of permanent atrial fibrillation in selected patients, today the Guidelines recommend carrying out radiofrequency transcatheter ablation (TCA-RF). This method is currently effective in about 70% of cases. In some cases, repetition of the ablation may be necessary to maintain the sinus rhythm.
Once atrial fibrillation is established, atrial tissue undergoes an “electrical” and “structural” remodeling, that is, changes in the electrophysiological and structural characteristics of the atrial myocardium towards fibrosis. These changes increase as a function of the duration of AF, decreasing the probability of restoring the sinus rhythm and maintaining it after cardioversion and after ablation. This concept is summarized by the phrase ”AF begets AF ”, that is “atrial fibrillation facilitates atrial fibrillation”. Therefore, today the Guidelines recommend carrying out ablation procedures in the early stage of atrial fibrillation, without postponing to a late stage in which atrial remodeling has already advanced.
After TCA-RF, it may be necessary to continue antiarrhythmic therapy and anticoagulant therapy. To guide the therapeutic management after ablation, the positioning of an implantable subcutaneous loop recorder, generally followed with remote monitoring, is useful.
When may pacemaker implantation be necessary for the management of atrial fibrillation?
In some cases, when the conduction beam towards the ventricles is damaged, and, therefore, the ventricular response of atrial fibrillation is particularly low, it may be necessary to resort to the implantation of a permanent pacemaker.
When it is not possible to control the ventricular response frequency of atrial fibrillation, which remains very high despite the drugs (beta-blockers and digital), it may be necessary to resort to ablation of the atrioventricular node associated with the implantation of a permanent pacemaker. In this case, a resynchronizer pacemaker (CRT-P) can often be chosen to maintain a physiological contraction in the two ventricles.
Bring to the table win-win survival strategies to ensure proactive domination. At the end of the day, going forward, a new normal that has evolved from generation.
Bring to the table win-win survival strategies to ensure proactive domination. At the end of the day, going forward, a new normal that has evolved from generation.
Pediatric arrhythmias are any changes in the regular, even rhythm of the heartbeat in children and in neonates.
Our center has great experience in dealing with the arrhythmias in children, even in neonates, particularly arrhythmias associated with congenital heart diseases. Our group has also contributed substantially to the progress of the treatment of tachyarrhythmias in children, with a major contribution to the scientific literature and to the current guidelines, particularly for the treatment of asymptomatic children with ventricular preexcitation (Wolff-Parkinson-White Syndrome, WPW).
In our center, pediatric arrhythmias are diagnosed and treated by implanting a pacemaker in cases of bradyarrhythmias (or slow arrhythmias), or by performing radiofrequency catheter ablation in cases of tachyarrhythmia (or fast arrhythmias), which can be definitively cured in most cases. Usually we have a conservative approach in children under 5 years old, and we perform catheter ablation in older children, preferably more than 10 years old. However, in children with tachyarrhythmias at risk of sudden death, cardiac arrest, syncope or heart failure, catheter ablation is mandatory and can be performed even in the first months of life or during earlier childhood.
Supraventricular arrhythmias
Supraventricular arrhythmias in children may occur either in the presence of a structurally normal heart or in the presence of congenital heart disease.
The incidence of atrioventricular reciprocating arrhythmias associated with WPW is 85% of arrhythmias during the fetal stage of life, and 82% of arrhythmias occurring during infancy. The incidence decreases to 65% in the 1-5 year-old age group, 56% in the 6-10 year-old age group, and 68% in children over 10 years of age. In most cases, tachycardias will resolve spontaneously by the end of infancy, but late recurrency may occur. Catheter ablation is frequently performed to treat tachyarrhythmias involving a single or multiple accessory pathway in highly symptomatic WPW children or in asymptomatic WPW children found at a high risk of sudden death.
Nodal reentrant tachycardia is uncommon during infancy, with an incidence of 23% in the 1-5 year-old age group, 34% in the 6-10 year-old age group, and 20% in those over 10 years of age. Most cases do not resolve spontaneously, requiring catheter ablation. Less common arrhythmias include atrial flutter and atrial ectopic tachycardia, with an incidence of about 10-15% during childhood, and most of them resolve spontaneously. If not, then persistent radiofrequency ablation is required to definitively cure them.
Ventricular arrhythmias
Ventricular tachycardias are rare in childhood. Ventricular arrhythmias are diagnosed in children using EKG, chest X-Ray, echocardiograms, an electrophysiological study, or cardiac magnetic resonance. These arrhythmias are generally benign, normally disappear during exercise, and have a good long-term prognosis. Ventricular tachycardia occurring in children in association with hypertrophic cardiomyopathy, long QT syndrome (LQTS), Brugada syndrome (BrS), and arrhythmogenic right ventricular cardiomyopathy (ARVC) may have a worse prognosis, and must be studied with great care on a case-by-case basis.
Right ventricular outflow tract (RVOT) tachycardia is occasionally discovered in teenagers and, in these cases, ARVC must be excluded. The EKG shows left bundle branch block (LBBB) with a vertical or right axis. This form of ventricular tachycardia is commonly induced by exercise or emotions, can be reproducibly induced by isoprenalin, and is responsive to RF catheter ablation.
Idiopathic left ventricular tachycardia arising from the posterior fascicle of the left bundle branch is rare, and it responds to radiofrequency ablation. Catecholaminergic ventricular tachycardia is also induced by emotion, exercise, or isoprenaline and may degenerate into polymorphic ventricular tachycardia (torsade de pointes), frequently causing syncope if it terminates spontaneously, or cardiac arrest and sudden death if it degenerates into ventricular fibrillation. Torsade de point may also occur in children with long QT-syndrome, a familial disease characterized by prolonged and abnormal ventricular repolarization and risk of life-threatening ventricular arrhythmias, cardiac arrest, or sudden death. The mortality among untreated symptomatic children is up to 70% within 15 years after the first syncopal episode. Treatment includes beta-blockade, antiarrhythmic drugs, left cardiac ganglionectomy, and implantable cardiac defibrillator (ICD).
Bradyarrhythmias
Complete atrioventricular block is the most important bradyarrhythmia in childhood. This arrhythmia may be congenital or may occur after cardiac surgery in congenital heart diseases. The symptom is usually syncope (loss of consciousness) due to the bradycardia, and the therapy generally is a pacemaker implant.
Symptoms
The symptoms of arrhythmias in children depends essentially on the underlying cardiac conditions, as well as on the age at presentation. Usually neonates and infants with fast supraventricular or ventricular arrhythmias present with congestive heart failure due to tachycardiomyopathy. This symptom may occur in permanent junctional reciprocating tachycardia, incessant atrial ectopic tachycardia, and ventricular tachycardia. Palpitations are generally the first clinical manifestation of tachyarrhythmias in older children, and require clinical investigation, generally with ECG and Holter recording. Syncope (loss of consciousness) may be due either to bradyarrhythmias or to ventricular tachyarrhythmias, and always requires a complete diagnostic work-up. Sudden death is uncommon in children, but when it occurs, it is generally caused by ventricular arrhythmias degenerating into ventricular fibrillation. In case of sudden death in children, a familial diagnostic work-up is generally recommended.
Our Experience with Pediatric Arrhythmias
Our center has specific experience with pediatric arrhythmias, and younger patients will be assisted by dedicated personnel throughout their clinical course, will be hospitalized with a parent, and will have dedicated leisure areas.
The heart contracts thanks to specialized cellular structures that generate electrical impulses and regulate their distribution in the heart itself.
In normal conditions the electrical impulse originates in the atrial sinus node, propagates in the atria and reaches the atrio-ventricular node, which is the only electrical communication path between the atria and ventricles; from here the impulse passes to the His bundle and to the intraventricular conduction system.
WHAT ARE BRADYARRHYTHMIAS?
They are heart conditions in which the heart rate is lower than normal. The damage that underlies this arrhythmia can be located at the sinus node (the area that generates the beat) or at the atrioventricular node (the region that allows the transit of the electrical impulse from the atrial to the ventricular chambers).
Bradyarrhythmias therefore include the various forms of sinus node disease and can be characterized by a generalized slowing of the beat or by a sudden absence of the beat itself (in the first case “bradycardia”, in the second case “sinus arrest”).
Atrioventricular blocks are conduction disturbances of the electrical impulse at the level of the atrioventricular node.
The atrioventricular blocks are divided by degrees:
first degree or slowed conduction,wherein all atrial impulses are conducted to the ventricles with delay;
second degree or intermittent conduction, in which some impulses are conducted and others blocked;
• third degree or complete block, in which no atrial impulses are conducted to the ventricles.
HOW TO RECOGNIZE THEM?
They can manifest with: • syncope (fainting)
marked arrhythmia • dizziness • asthenia
HOW TO TREAT THEM?
In some cases, bradyarrhythmias are caused by medications and regress when the medications are stopped. In other cases, particularly when bradyarrhythmias cause symptoms, it is necessary to treat them with the implantation of the pacemaker.
Syncope is defined as a loss of consciousness characterized by sudden onset, short duration, and spontaneous and generally complete recovery of consciousness. The onset of syncope can be sudden, or preceded by warning symptoms (called “prodromes”) such as dizziness, sweating, nausea, asthenia. Syncope is a symptom frequently encountered in clinical practice and is responsible for approximately 1-3% of emergency room visits.
What are the causes of syncope?
The mechanism that causes syncope is a transient reduction in cerebral perfusion, due to a reduction in blood flow (i.e. “systolic flow”).
Sudden syncope can have different causes, and the recent “European Society of Cardiology” “Syncope Guidelines” of 2018 identifies three main etiological classes:
neuro-mediated syncope (or reflex or vaso-vagal)
syncope from orthostatic hypotension
cardiac syncope
While neuromediated syncope and orthostatic hypotension syncope are typically benign, cardiac syncope is often associated with heart disease and generally has a worse prognosis, and can also prove fatal.
What is neuromediated (or vasovagal or reflex) syncope?
Neuro-mediated (or vasovagal or reflex) syncope results from a transient anomaly in the functioning of the autonomic nervous system, responsible for regulating blood pressure and heart rate. Neuromediated syncopes are the most frequent in the general population, mainly affecting young people and are a benign disorder. If very frequent, however, it can create risky situations for the patient or for other people, for example while driving. The pathogenetic mechanism depends on an intense vagal activation that stimulates cardiac receptors that cause slowing of the heart rate and hypotension with the onset of syncope.
Neuromediated syncope often occurs during typical situations, such as standing in crowded or hot places, after strong emotions, or even during urination. The most effective “therapy” consists in trying to prevent those situations that often lead to syncope, and in learning to recognize the warning symptoms, thus assuming the sitting position or lying down to prevent complete loss of consciousness. In some cases, low-dose beta-blockers or aminophylline drugs can be used.
What is orthostatic (or postural) hypotension syncope?
Orthostatic (or postural) hypotension syncope depends on an excessive drop in blood pressure when standing upright. The accepted definition is a drop > 20 mmHg of systolic, 10 mmHg of diastolic, or both. Syncope is often preceded by prodromes such as weakness, clouding, dizziness, confusion or blurred vision that occur within minutes of positioning upright and quickly disappear while lying down. Exercising or a heavy meal can accentuate the symptoms.
The most frequent causes of acute orthostatic hypotension include a reduction in palsmatic volume (hypovolemia), the use of drugs, prolonged bed rest, age-related changes in blood pressure regulation, autonomic dysfunction (for example in Parkinson’s disease or diabetes mellitus).
Postprandial orthostatic hypotension is also frequent, and can be caused by insulin response to carbohydrate-rich meals and blood collection in the gastrointestinal tract, and is worsened by alcohol intake.
Orthostatic hypotension syncope is more frequent in the elderly patient, and the main problems involve being a fall risk, i.e. head injury or a fracture of the pelvis or femur, which can be accompanied by a syncope that occurs when moving to an upright position.
Some precautions can reduce the risk of orthostatic syncope, such as drinking a lot of water and ensuring a correct intake of salt, reducing hypotensive drugs, avoiding standing for a long time without moving, trying to move from sitting to standing upright, avoiding abrupt movement, and engaging in constant physical activity.
What is cardiac syncope?
Cardiac syncope is caused by an abrupt reduction in cardiac output, due to cardiac arrhythmias (bradyarrhythmias and tachyarrhythmias) or from structural heart disease (myocardial infarction, hypertrophic cardiomyopathy, valvular heart disease, atrial myxoma, or cardiac tamponade) or vascular (such as pulmonary embolism, aortic dissection, or congenital anomalies of the coronary arteries).
Arrhythmic causes include forms due to bradyarrhythmias, such as brady-tachi syndrome, blockages of atrioventricular conduction, malfunction of implantable cardiac devices, or drug-induced bradycardia.
Among the causes of arrhythmias due to tachyarrhythmias, there are supraventricular tachyarrhythmias (including atrial fibrillation and paroxysmal supraventricular tachycardias) and ventricular tachycardias and ventricular fibrillation, due to primary electrical heart diseases (called channelopathies, including Brugada syndrome, long QT syndrome, catecholaminergic ventricular tachycardia), or due to acute or chronic ischemic heart disease or arrhythmic cardiomyopathies (arrhythmic heart disease of the right ventricle, hypertrophic cardiomyopathy, dilated heart disease, etc).
Cardiac syncope most often requires emergency treatment, with the need to bring the patient to the emergency room, since in some cases it puts the patient at risk of sudden death.
In the case of suspected cardiac syncope, a thorough diagnostic procedure is necessary, and in the case of diagnosis of arrhythmic syncope, the use of antiarrhythmic drugs, or the implantation of a pacemaker, or a defibrillator, or transcatheter ablation procedures may be necessary.
How is the diagnosis of syncope made?
According to the recent guidelines of the European Society of Cardiology of 2018, patients with syncope must undergo an accurate medical history, physical examination, blood pressure measurement in a lying and standing position, and a 12-lead ECG.
Conditions must be reported by the patient, including the conditions preceding the syncope, those related to the onset of the syncope and its modalities, the end of the syncope and any disturbances that persist after the recovery of consciousness, the history of previous cardiac, metabolic and neurological pathologies and the recurrence of syncope, that is, the time from the first episode and the number of episodes. The initial evaluation, if well done, allows to ascertain the etiology of syncope in about half of the cases.
The physical examination must include the detection of the following parameters:
In the case of recurrent syncopes of suspected neuromediated origin, the execution of the Tilt test with evaluation of the autonomic nervous system is indicated.
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