Pediatric idiopathic ventricular tachycardia

Introduction to pediatric idiopathic ventricular tachycardia Idiopathic ventricular tachycardia (IVT) is referred to as idiopathic ventricular tachycardia. It refers to ventricular tachycardia with no evidence of organic heart disease and any arrhythmogenic factors, mild clinical manifestations, and good prognosis. Overspeed, because the origin of tachycardia is mostly located in the left branch of the left bundle branch under the His bundle branch or the anterior branch and the right bundle branch, also known as branch ventricular tachycardia. It accounts for about 10% of the incidence of ventricular tachycardia. The cause of idiopathic ventricular tachycardia is unclear, and many studies suggest that its mechanism is associated with triggering activation after degeneration or delayed depolarization. Compared with ventricular tachycardia after ischemic heart disease, the QRS shape of idiopathic ventricular tachycardia has the following characteristics: the degree of QRS widening is small, the frontal ECG axis is less offset, and there is no qR Or QR type of QRS. basic knowledge The proportion of illness: 0.0005% Susceptible people: children Mode of infection: non-infectious Complications: heart failure cardiogenic shock

Etiology of idiopathic ventricular tachycardia in children

Hemodynamic changes (30%):

The etiology of this disease is unknown. I have undergone endocardial myocardial biopsy in patients with IVT. Some patients have mild myocarditis or cardiomyopathy changes. They are considered to be subclinical myocarditis. The VT episodes in some IVT patients are induced by mental factors or exercise. Due to the balance of sympathetic-parasympathetic nervous system, some reported that IVT is a familial disease, which may be related to heredity. The pathogenesis of electrophysiological research may be micro-reentry or triggering activity of Purkinje fiber web.

Sudden cardiac death (30%):

There are many classification methods for idiopathic ventricular tachycardia. The most common classification is based on the origin of ventricular tachycardia. The classic origin of idiopathic ventricular tachycardia is the right ventricular outflow tract and left ventricular septum. The idiopathic right ventricular outflow tract (RVOT) ventricular tachycardia and idiopathic left ventricular tachycardia (ILVT), a few idiopathic ventricular tachycardia originated in other parts of the ventricle, and some scholars based on ventricular tachycardia for drugs or exercise The response was divided into verapamil-sensitive VT, adenosine-sensitive VT, catecholamine-dependent VT, and exercise-induced ventricular tachycardia. (exercise-induced VT).

Electrophysiological characteristics (25%):

According to intracardiac electrophysiological studies and its response to verapamil, it is speculated that the possible mechanisms of occurrence are reentry agonism and triggering agonism. Electrophysiological mechanisms and characteristics: This type of ventricular tachycardia is usually not induced by procedural stimulation, and can be instilled intravenously. Isoproterenol or atrial, ventricular short burst rapid pacing pacing induced, beta blocker or calcium ion antagonist treatment effective characteristics, suggesting that this type of ventricular tachycardia may be caused by delayed depolarization Triggering about the excitement.

Childhood idiopathic ventricular tachycardia prevention

The cause of this disease is unknown, and the predisposing factors should be actively prevented. For example, mental factors or exercise can be induced, and the child should be promoted, the heart should be healthy, and strenuous exercise should be avoided.

Complications of idiopathic ventricular tachycardia in children Complications heart failure cardiogenic shock

Can be complicated by heart enlargement, heart failure, cardiogenic shock and so on.

Children with idiopathic ventricular tachycardia symptoms Common symptoms tachycardia chest tightness arrhythmia palpitations dizziness heart enlargement heart failure conduction block atrioventricular septal shock

Idiopathic ventricular tachycardia can occur in children and adolescents of all age groups. It is reported that the minimum age is 1 year old, upper respiratory tract infection, exercise or mental stress and depression are often induced factors, and can occur without obvious incentives. The episode can be characterized by sudden onset, mild palpitations, discomfort in the anterior region, without syncope, shock, etc.; it can also be a persistent episode, depending on the length of time, palpitations, chest tightness, dizziness, Even syncope, shock and heart failure, but overall tolerability, idiopathic ventricular tachycardia patients without structural heart disease, the cause of the disease is unknown, Janet et al on 18 cases of idiopathic Myocardial biopsy was performed in patients with ventricular tachycardia. Among them, 16 cases had abnormal myocardial tissue, so the disease was proposed as subclinical cardiomyopathy.

1. Clinical manifestations and ECG characteristics: Hemodynamic changes are not obvious when tachycardia occurs, children have no obvious symptoms, less syncope, and tachycardia ECG shows right bundle branch block (RBBB) pattern. The electric axis is left-biased and has a narrow QRS complex (120ms).

2. Triggered activity: the interval between the pre-expiration stimulus and the induced first pulsation of the ventricular tachycardia. The support trigger activity may be the mechanism of this arrhythmia. Bhandari et al reported a case of arrhythmia. In patients with primary left ventricular tachycardia, the left ventricular endocardial monophasic action potential recorded at the onset of ventricular tachycardia and the high amplitude delayed depolarization (DAD) on the 4th phase are direct evidence of triggering agitation. Patients with left ventricular tachycardia are sensitive to verapamil, intravenous verapamil, ventricular tachycardia gradually slows down and then terminates, program stimulation can not induce it, suggesting two possible idiopathic left ventricular tachycardia Mechanism of occurrence: reentry agonism or triggering agonism, both rely on the activity of the slow channel of the cell membrane. The reentry-reversed reentry loop contains slow-channel tissue, and the triggering is triggered by delayed depolarization (DAD).

Examination of pediatric idiopathic ventricular tachycardia

General cardiac examination, including physical examination, X-ray, conventional electrocardiogram, two-dimensional echocardiography and magnetic resonance examination, were normal.

Check for myocardial enzyme measurement, blood electrolysis value, pH value and immune function. The ventricular tachycardia is monomorphic. According to the cause of IVT seizure, electrocardiogram performance and response to drug treatment, it can be divided into left ventricular, right ventricle and catecholamine sensitive IVT.

Left ventricular IVT: The QRS wave is a right bundle branch block with a left-biased electric axis. Most of the ectopic impulse originates from the Purkinje fiber network in the left posterior branch. This type is more common. A few of the Purkinje fiber webs originating from the left anterior branch, the QRS wave is blocked by the right bundle branch with the right axis of the electric axis. Verapamil (isopidine) can effectively control the onset of IVT and prevent recurrence, while lidocaine, propranolol (propranolol) and other drugs are ineffective.

Non-sustained IVT can be asymptomatic, or palpitations, dizziness. Hemodynamic changes, heart enlargement, heart failure or syncope may occur if the heart rate is high for a long time. The ventricular tachycardia occurred in children of all age groups, with persistent or non-sustained seizures. The clinical manifestations were mild and well tolerated, with typical ECG characteristics. The tachycardia electrocardiogram showed right bundle Conduction block (RBBB) pattern, the left axis of the electric axis is narrow QRS complex (120ms). Electrocardiogram is the main means of the disease. When the ECG is difficult to distinguish from paroxysmal supraventricular tachycardia, the feasible esophageal ECG finds that the atrioventricular septum helps to confirm the diagnosis.

Diagnosis and diagnosis of idiopathic ventricular tachycardia in children

diagnosis

General cardiac examination, including physical examination, X-ray, conventional electrocardiogram. Two-dimensional echocardiography and magnetic resonance imaging, no abnormalities, non-sustained IVT can be asymptomatic, or palpitations, dizziness, prolonged seizures for a long time, rapid heart rate, hemodynamic changes, heart enlargement, Heart failure or syncope, long-term follow-up results show that the majority of patients with IVT have a good prognosis, may have recurrence, after anti-arrhythmia treatment, can be satisfactorily controlled, rarely sudden death, ventricular tachycardia occurring in children of all age groups Sustained or non-sustained seizures, generally mild clinical manifestations, well tolerated, typical ECG characteristics, especially with the first 3 (see VT) conditions, tachycardia ECG showed right bundle Conduction block (RBBB) pattern, left axis deviation, narrow QRS complex (120ms), no other systemic diseases and electrolyte disturbances that cause heart damage during the attack, cardiac two-dimensional echocardiography, chest X-ray, The electrocardiogram shows that the heart structure is normal. The electrocardiogram is the main means of the disease. When the ECG is difficult to distinguish from paroxysmal supraventricular tachycardia, the esophageal electrocardiogram can be found in the separation of the atrioventricular septum. Confirm the diagnosis.

Differential diagnosis

1. Identification of epilepsy: exercise-induced IVT can suddenly occur syncope, should be differentiated from epilepsy, the latter with normal electrocardiogram and abnormal EEG.

2. supraventricular tachycardia: idiopathic ventricular tachycardia may be due to ventricular rate, P wave is not easy to find, QRS wave deformation is not obvious, patient tolerance is good and diagnosis, but should be with supraventricular tachycardia Overspeed and supraventricular tachycardia with indoor differential conduction or pre-excitation syndrome for identification, identification points:

(1) Abnormal P wave: Read the electrocardiogram carefully, and the abnormal P wave can be seen. The idiopathic ventricular tachycardia has compartmental separation, and there is a ventricular fusion wave or a ventricular capture wave.

(2) separation of the atrioventricular compartment: ECG examination of the esophagus, typical room separation can be seen in the idiopathic ventricular tachycardia.

(3) Stimulation of the vagus nerve: oppression of the eyeball, carotid sinus and other stimulating vagus nerve treatments are effective for supraventricular tachycardia and ineffective for ventricular tachycardia.

(4) esophageal atrial pacing: can terminate supraventricular tachycardia, but can not terminate ventricular tachycardia.

3. Catecholamine-related ventricular tachycardia: catecholamine-related ventricular tachycardia and idiopathic ventricular tachycardia are seen in normal children without structural heart disease, but the former manifests as sudden syncope See, often induced by exercise or emotional stress, may be persistent or non-sustained episodes, and have a family tendency, electrocardiographic features are more common in polymorphic ventricular tachycardia, and changes in electrocardiogram to monomorphic catecholamines Ventricular tachycardia is difficult to distinguish from idiopathic ventricular tachycardia, which many authors refer to as idiopathic ventricular tachycardia.

4. Arrhythmogenic right ventricular dysplasia: idiopathic ventricular tachycardia with left bundle branch block pattern on ECG should be differentiated from the disease, cardiac X-ray, ultrasound in patients with arrhythmogenic right ventricular dysplasia And ventricular angiography often suggests that the right ventricle is enlarged, and the contractile force is significantly weakened. Cardiac MRI examination can find adipose tissue in the myocardium, and the right ventricle is the main, which can help identify.

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