Ventricular tachycardia is a cardiac arrhythmia characterized by an increase in ventricular heart rate.
The ventricles contract too quickly and in a disorganized way with respect to the atria → they fail to fill adequately → the amount of blood pumped in a circle is reduced with each beat → the arterial contour decreases → the amount of blood that oxygenates and nourishes the blood is also reduced heart (coronary circulation) → the contractile efficacy of the heart is further reduced → degeneration in ventricular fibrillation → death.
This unfortunate evolution is more likely in the case of very high ventricular rate and in case of cardiac base compromises in cardiac patients.
Ventricular tachycardia is one of the most common arrhythmias in patients with heart disease. Although it can also occur in healthy subjects, it represents an arrhythmia to be treated with care: it can in fact degenerate into ventricular fibrillation, the outcome of which is often fatal.
The best prevention is to adopt a healthy lifestyle.
What is ventricular tachycardia
Ventricular tachycardia is one of the most common and most dangerous arrhythmias. Usually, there is a serious heart disorder, but it can also occur in healthy individuals.
Pathogenesis
Ventricular tachycardia occurs when the normal pulse of cardiac contraction undergoes a modification.
The normal impulse arises in the atrial sinus node, but it may happen that extra impulses ( extrasystoles ) arise at points other than the atrial sinus node (ectopic arrhythmias). This event alters the normal heartbeat.
During ventricular tachycardia, 3 or more ventricular extrasystoles occur in succession, which speed up the heart rate and originate distally from the bundle of His.
Consequences
The regular contraction of the ventricle is responsible for cardiac output . Cardiac output refers to the pumping action of circulating blood towards the lungs and tissues of the human body.
An altered ventricular contraction rhythm results in insufficient cardiac output. Therefore, oxygenated blood does not irrigate the tissues and organs of the body, including the heart, which further loses its contractile efficacy. If this deficit is severe the patient goes to death.
Epidemiology
Incidence data says that:
- Ventricular tachycardia is age-related : it occurs more frequently in middle-aged and old-age individuals.
- 2-4% of those over the age of 60, without heart problems, experience episodes of ventricular tachycardia.
- 4-16% of those over the age of 60, with heart disease, experience episodes of ventricular tachycardia.
In addition, the manifestations of ventricular tachycardia:
- They are more frequent in the winter months.
- They have a circadian pattern: the peak incidence is observed in the morning hours.
Classification
It can be based on several parameters, summarized in this table:
| Criterion | Form of tachycardia | Form of tachycardia |
| Duration | Not supported : it runs out in less than 30 seconds | Sustained : lasts more than 30 seconds |
| Onset methods | Paroxysmal : sudden onset, sporadic, abrupt and unpredictable. Tachycardia can exhaust itself on its own. | Not paroxysmal : more gradual onset. Tachycardia is usually permanent and linked to heart disorders |
| Electrocardiographic tracing | Monomorphic . The beats, albeit accelerated, are identical to each other. Regularity of rhythm | Polymorphous . The beats are accelerated and different from each other. Irregularity of rhythm |
Causes of ventricular tachycardia
The main causes of ventricular tachycardia are heart disease .
Causes related to electrolyte imbalances follow, which alter the electrical activity of the heart.
Finally, there are a number of risk factors that predispose the individual to episodes of tachycardia.
Heart disease
Those most affected by ventricular tachycardia are heart patients . The cardiac diseases observed in these patients are:
- Coronary artery disease and previous myocardial infarctions
- Valvulopathies, ie malfunctions of one of the heart valves.
- Cardiomyopathies, ie diseases of the myocardium (the heart muscle).
Coronary artery disease causes ischemia (ischemic heart disease) and is the most common cause of ventricular tachycardia.
The most common valvulopathies are those involving the mitral valve (see Mitral insufficiency).
Cardiomyopathies are rheumatic in nature: in other words, they originate from inflammation of the bacterial type. In these cases we speak of myocarditis .
A small percentage of cases of ventricular tachycardia is also due to congenital heart disease (that is, present since birth). The best known are:
- Brugada syndrome.
- Wolff-Parkinson-White syndrome
Less frequent, instead:
- Tetralogy of Fallot.
- Marfan syndrome.
Ionic / electrolyte imbalances
The myocardial contraction impulse is an electrical signal . In fact, it moves the ions, which have a positive and negative charge, present inside the heart cells. The movement of these ions is similar to the movement of the charges in an electrical circuit and results in the contraction of the heart muscle .
The main ions, with charge, are: potassium, magnesium, calcium and sodium. Among them there is a fine balance, which must be maintained such, for the proper functioning of the muscle cell and not only. It may happen that this balance is altered. As a result, the contraction pulse is also modified and ventricular tachycardia occurs. The main ionic / electrolytic imbalances are:
- Hypokalemia, or hypokalemia.
- Hypocalcemia.
- Hypomagnesemia.
Other risk factors
There are risk factors that favor the onset of episodes of tachycardia even in healthy subjects. These are special circumstances, such as severe chest trauma or taking certain medications. A summary of the main risk factors is as follows:
- Taking drugs:
- Tricyclic antidepressants.
- Cocaine abuse.
- Alcohol abuse.
- Smoke.
- Caffeine.
- Gas poisoning:
- Cyclopropane.
- Carbon monoxide.
- Chest trauma.
- Physical and emotional stress.
Symptoms and complications
The typical symptoms of ventricular tachycardia are:
- Palpitation, or heartbeat.
- Chest pain.
- Dyspnoea.
- Dizziness.
- Fainting.
- Syncope.
- Shortness of breath.
Most patients have this symptomatology in association with ischemic heart disease or which compromises blood flow (for example, a valvulopathy).
Signs
Your doctor may find the following clinical signs:
- Accelerated pulse.
- Hypotension.
- Anxiety.
- Agitation.
- Loss of consciousness.
Their appearance depends on the extent of the heart disorder: the more serious it is, the easier it is for them to manifest themselves.
Complications
Ventricular tachycardia can degenerate into ventricular fibrillation . This occurs mainly in people with heart disease, while cases in healthy people affected by paroxysmal ventricular tachycardia are very rare.
Ventricular fibrillation usually has a fatal course . It determines the patient's death:
- For sudden cardiac death.
- For cardiac arrest.
Diagnosis
Several surveys can be carried out, each of which has a specific advantage. They are:
- Electrocardiogram (ECG).
- Echocardiography.
- Chest x-ray.
- Coronary angiography.
- Blood tests.
ECG
It is the test of choice . It measures the electrical activity of the heart and allows the identification of the form of ventricular tachycardia that affects a patient. It is also possible to monitor cardiac activity within 24 hours; in this case, the dynamic ECG according to Holter is used . It is a useful investigation when the form of ventricular tachycardia is paroxysmal, ie sporadic and unpredictable onset.
Echocardiography
This is a non-invasive test. It uses ultrasound to evaluate the health of the main structures of the heart: atria, ventricles and valves. It is useful when a valve disease is suspected.
Chest x-ray
Provides information on the relationship between heart and lungs. At the origin of a ventricular tachycardia there can be a pulmonary thrombosis. This is an invasive test, because it uses ionizing radiation.
Coronary angiography
It is an invasive exam. It is necessary when there is ischemic heart disease at the origin of ventricular tachycardia. Measure the position and degree of occlusion of the coronary arteries, to plan a possible surgical intervention. It is a delicate test, as it runs the risk of damaging the coronary vessels crossed by the catheter.
Blood tests
They provide different information on:
- Ion / electrolyte concentrations:
- Calcium levels
- Magnesium levels
- Phosphate levels
- Concentration of some drugs taken by the patient.
- Concentration of some cardiac markers.
Therapy
A premise: when at the origin of ventricular tachycardia there is heart disease, the goal of treatment is twofold:
- Resolve basic heart disorder . Primary objective.
- Solving the arrhythmic disorder . Secondary objective.
This is explained because the second problem is a consequence of the first.
"Healthy" patients with sporadic tachycardia
In those who are not suffering from heart disease, ventricular tachycardia can resolve spontaneously. Therefore, drug administration can be avoided. In any case, it is advisable to consult a doctor and undergo thorough investigations.
"Healthy" patients with sustained or persistent tachycardia
If the patient manifests numerous episodes of sustained type, to block the attack of tachycardia, one can make use of:
- Pharmacological cardioversion.
- Electrical cardioversion.
Pharmacological cardioversion is the restoration of normal heart rhythm by taking drugs:
- Antiarrhythmics, to restore a normal heart rhythm.
- Lidocaine
- Amiodarone
- Procainamide
- Beta-blockers, to slow down the heart rate.
Electrical cardioversion consists of:
- Electric discharge to reset and restore normal sinus rhythm. Use of a device equipped with two plates applied to the patient's chest. It is a technique also known as defibrillation . Today, there are semi-automatic and automatic defibrillators, capable of assessing the degree of ventricular tachycardia and imparting the right electrical discharge. The other big advantage is that they can be used by non-medical personnel.
Cardiac patients or with other pathologies
The drug therapy is the same as described above. Then:
- antiarrhythmics
- Beta blockers.
To these are added:
- Anticoagulants, to avoid the formation of thrombi and emboli, due to valvulopathies.
In addition to electrical cardioversion, surgery can be performed with:
- Trans-catheter radiofrequency ablation . Through a catheter conducted to the heart, a radiofrequency discharge is infused at the point of the ventricle that generates the arrhythmia. The affected area is destroyed and this should restore normal heart rhythm. It is an invasive technique.
- Implantable defibrillator (ICD) . It is a normal defibrillator, which is, however, implanted under the skin, on the left side of the chest. It is connected to the heart by means of electrodes, which emit an electric discharge when they experience an abnormal increase in heart rate. They last 7-8 years, after which they must be replaced. A possible problem may be due to the malfunction of the appliance, which may emit unplanned electric shocks.
The therapy to be adopted must be chosen, of course, case by case, without forgetting that the first therapeutic intervention must resolve the possible pathological problem that generates the ventricular tachycardia. Below is a table that summarizes the possible therapy.
| Therapy | Sustained / permanent ventricular tachycardia in "healthy" patients | Ventricular tachycardia in cardiac patients or with other serious pathologies |
| drugs | Antiaritimici:
| Antiaritimici:
Anticoagulants. |
| Electrical cardioversion | Yup | Yup |
| Implantable Defibrillator (ICD) | No | Yup |
| Trans-catheter radiofrequency ablation | No | Yup |
Prevention
Adopting a healthy lifestyle is the best prevention. Then:
- Stop smoking.
- Limit alcohol consumption.
- Change the diet.
- Don't use drugs.
- Practicing physical exercise.
Tobacco and alcohol are responsible, not only for sporadic episodes of tachycardia, but also for chronic changes in heart rhythm. In fact, they are among the most common risk factors in the development of heart disease.
Changing your habits at the table is another fundamental preventive step. It is advisable to reduce fat, red meat and increase fruit and vegetable consumption.
Adopting healthy habits removes the possibility of ventricular tachycardia degenerating into ventricular fibrillation. The latter is almost always fatal.
Population at risk
Those who:
- They present pathological conditions, such as hyperlipidemia, hypertension and diabetes. These promote the development of heart disease.
- They have a family history of coronary heart disease.
- Smoking.
- Alcoholics.
