Heart block in a baby

What is heart block in a child? As in adults, heart block in childhood means a disruption in the conduction of electrical impulses that, passing through from the atria to the ventricles of the heart, ensure rhythmic contraction of the heart muscle and its normal pumping function.

Thus, heart block is an atrial ventricular or atrioventricular block (AV block) resulting from abnormalities in the conduction system of the heart. [1]

What factors can trigger heart block in a child?

In children, heart block can be caused by congenital defects in the conduction system of the heart, which occur in the presence of structural congenital heart defects, including atrial septal defects, valve anomalies, open ductus arteriosus, and transposition of the main arteries. Heart block affects one-third of fetuses with heterotaxy syndrome (left-right organ placement abnormalities) with right isomerization of the left atrium. [2]

AV blockade in a child can also be triggered by:

• Rheumocarditis leading to myocardial damage, which in children develops after an ear disease caused by Streptococcus pyogenes (β-hemolytic streptococcus group A), e.g. Tonsillitis or otitis media;
• Myocardial damage of an inflammatory or autoimmune nature - myocarditis in children; [3]
• Lyme disease (lyme borreliosis);
• hypertonicity of the parasympathetic branch of the autonomic nervous system - increased irritation of the vagus nerve (nervus vagus), which is manifested by impaired vagal innervation of the heart; [4]
• surgery to correct a congenital heart defect. [5]

In childhood, heart rhythm and conduction abnormalities are associated with gene mutations in Kearns-Seir syndrome, a mitochondrial disease that manifests from the age of four. [6]

And in hereditary Brugada syndrome in children there is complete or incomplete block of the right leg of the heart in the child - right bundle branch block of the Hiss (where the signal from the AV node travels down the right atrium to the ventricle). [7], [8]

Congenital incomplete heart block in the child may occur in the prenatal period, when between 16-28 weeks of gestation there is intrauterine damage to the AV node of the fetal heart by maternal antibodies (SSA/Ro or SSB/La) with autoimmune connective tissue diseases, most commonly systemic lupus erythematosus [9] and Sjögren's syndrome. [10] But these antibodies, which cause fibroelastosis of cardiac conduction system structures, may be present in 2-3% of healthy asymptomatic women.

In rare cases, pediatric heart block is idiopathic, meaning it occurs in the absence of structural heart abnormalities, the influence of maternal antibodies, or other obvious causes.

What symptoms accompany heart block in a child?

In some children, this condition does not cause symptoms. Thus, heart block of the 1st degree in a child (AV blockade of the first degree) means a slowing of the passage of impulses through the atrioventricular node (AV node) of the interatrial septum without disruption of atrial-ventricular conduction. Most often such blockade is asymptomatic (because nodal replacement rhythm develops), but there may be a decrease in heart rate - atrioventricular bradycardia. [11]

Grade 2 heart block in children (Grade II AV blockade) may present with symptoms of bradycardia in children. [12]

Complete heart block in a child leads to complete dissociation of atrial and ventricular activity as a result of damage to the atrioventricular conduction pathways. In children with AV blockade of the III degree, the electrical activity of the upper and lower chambers of the heart is not coordinated (because impulses from the atria do not reach the ventricles). [13] In this case, the atrial rate is within the normal range, and the ventricular rate may be less than 50 beats per minute. This cardiac conduction disorder is accompanied by sinus bradycardia, causing dizziness, dyspnea, arrhythmogenic syncope (fainting), rapid fatigue and general weakness with exercise intolerance. [14], [15]

Infants with congenital incomplete and complete heart block have lividity of the skin, lethargy, decreased feeding activity (resulting in underweight), and seizures.

What possible complications can occur with heart block in a child?

Among the possible complications of heart block in children, cardiologists include the progression of mild blockade to higher degrees of atrial dysfunction, which leads to atrial fibrillation (atrial fibrillation). [16]

The main danger of heart block is the development of life-threatening heart rhythm disturbances and sudden cardiac arrest. [17]

How is heart block diagnosed in a child?

Heart block is diagnosed by recording the electrical activity of the heart - electrocardiography (ECG). [18], [19]

Also used are echocardiography (cardiac ultrasound) and x-ray examination of heart function.

To find out the causes of this disorder, blood tests are necessary: biochemical, for rheumatoid factor, the level of immune complexes, antinuclear and antiphospholipid antibodies, etc.

Sometimes congenital complete heart block is diagnosed intrauterine - using fetal cardiotocography.

How to treat heart block in a child?

Usually, heart block in a child needs treatment only when symptoms are present.

Grade I AV blockade is rarely symptomatic and does not require treatment, as does Hiss bundle branch blockade.

In many cases, complete heart block requires a pacemaker. For newborns and children with complete atrioventricular block, the main method of treatment (correction of the block) is the installation of a pacemaker implanted under the skin. In 2nd degree heart block, the need for a pacemaker is rare. [20]

For more information, see. - Pacemaker surgery

Before surgery, the necessary rhythm of heart muscle contraction can be maintained with drugs such as Dobutamine, Izadrin, Isoproterenol, Orciprenaiin Sulfate and other beta-adrenomimetics.

Children with Kearns-Seir syndrome and mitochondrial cardiomyopathy - to improve metabolism and tissue respiration of myocardial cells, as well as reduce oxidative stress - are prescribed to take vitamins C, E and B group, as well as supplements with the amino acid L-carnitine: Carliv, Cardonate, Elcar, Metacartin and others.

What are the risks of performing surgical treatment for heart block in children?

Implanting and maintaining a pacemaker involves certain risks, including:

• subcutaneous hemorrhaging;
• an infectious inflammation of the inner lining of the heart called endocarditis;
• lack of ventricular synchronization;
• with the onset of arrhythmia;
• by electrode displacement;
• an autoimmune reaction leading to rejection of the pacemaker.

What recommendations will help me improve my child's health if he or she is diagnosed with heart block?

Children with birth defects tend to have difficulty gaining weight because they use more energy to breathe and digest food. Parents often feed their young child more calorie-dense foods, which can lead to overweight by age 7 because children gain weight faster than they grow.

Therefore, nutritional guidelines should be followed to improve the child's health:

• Include in your diet a sufficient amount of dietary fiber, which is found in whole grain products, legumes, fresh fruits and vegetables;
• Reduce the child's intake of dietary fats, i.e. Fatty meats and dairy products;
• ensure the intake of polyunsaturated fatty acids - omega-3 fatty acids, which are rich in vegetable oils and fish oil;
• Limit cholesterol levels, i.e. Red and processed meats, fried foods and baked goods;
• reduce salt intake;
• teach your child to drink enough water.

In addition, it is very important to minimize the physical activity of the child experts know that physical exercise and active games are useful for children with heart defects and 1-2 degree of heart block.

However, a pediatric cardiologist may recommend limiting certain types of physical activity, and parents should follow these recommendations precisely.

What are some methods for preventing heart block in children?

According to recent studies, in cases of 1st degree fetal heart block due to transplacental exposure to maternal antibodies to SSA/Ro or SSB/La, it is possible to normalize the conduction system of the fetal heart fairly quickly if the pregnant woman takes the antimalarial drug Hydroxychloroquinone (used in lupus erythematosus and rheumatoid arthritis) with fluorinated corticosteroids such as Dexamethasone. Weekly fetal echocardiography is required from the 16th week of pregnancy onwards.

What is the prognosis for life with heart block in children?

In pediatric heart block, the prognosis depends on its cause and the degree of conduction disturbance.

In the presence of congenital heart disease with congenital heart block, mortality is estimated at 6-8%.

The average mortality rate of newborns with autoimmune congenital AV blockade due to transmission of specific antibodies from the pregnant woman to the developing fetus via the placenta is 15-20%.