Ventricular tachycardia is a "cardiac arrhythmia characterized by an increase in the ventricular heart rate.
The ventricles contract too quickly and in a disorganized way compared to the atria → they are unable to fill properly → the amount of blood pumped into the circulation with each beat is reduced → the arterial pressure decreases → the amount of blood that oxygenates and nourishes the heart (coronary circulation) → the contractile efficacy of the heart is further reduced → degeneration into ventricular fibrillation → death.
This unfortunate evolution is more likely in the case of very high ventricular rate and in the case of underlying cardiac compromise in cardiac patients.
Ventricular tachycardia is one of the most common arrhythmias found in patients with heart disease. Although it can also occur in completely healthy subjects, it represents an "arrhythmia to be treated carefully: 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, a serious heart disease originates "c", but it can also occur in healthy individuals.
Pathogenesis
Ventricular tachycardia occurs when the normal pulse of cardiac contraction undergoes a change.
The normal impulse arises in the sinoatrial node, but it can happen that extra impulses (extrasystoles) arise in points other than the sinus node (ectopic arrhythmias). This event alters the normal heart beat.
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.
Aftermath
Regular contraction of the ventricle is responsible for cardiac output. By cardiac output we mean the pumping action of the blood into the circulation towards the lungs and tissues of the human body.
An altered ventricular rhythm of contraction results in insufficient cardiac output. Therefore, oxygenated blood no longer properly irrigates the tissues and organs of the body, including the heart, which further loses its contractile effectiveness. If this deficit is severe, the patient goes to death.
Epidemiology
The data relating to the incidence show that:
- Ventricular tachycardia is age-related: it occurs more frequently in middle-aged and older people.
- 2-4% of over-60s without heart disease experience episodes of ventricular tachycardia.
- 4-16% of over 60s 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:
Causes of ventricular tachycardia
The main causes of ventricular tachycardia are heart disease.
There follow causes linked to electrolyte imbalances, which alter the electrical activity of the heart.
Finally, there is a series of risk factors that predispose the individual to episodes of tachycardia.
Heart disease
The people most affected by ventricular tachycardia are heart patients. The heart diseases observed in these patients are:
- Coronary artery disease and previous myocardial infarctions
- Valvulopathies, that is, malfunctions of one of the heart valves.
- Cardiomyopathies, i.e. diseases of the myocardium (the heart muscle).
Coronary heart 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 a "bacterial inflammation. In these cases, we speak of myocarditis.
A small percentage of cases of ventricular tachycardia are also due to congenital heart disease (i.e. present from birth). The best known are:
- Brugada syndrome.
- Wolff-Parkinson-White syndrome
Less frequent, however:
- Fallot's Tetralogy.
- Marfan syndrome.
Ionic / electrolyte imbalances
The impulse of contraction of the myocardium is an electrical signal. In fact, it moves the ions, with a positive and negative charge, present inside the cells of the heart. The movement of these ions is similar to the movement of charges in an electrical circuit and results in the contraction of the heart muscle.
The main charged ions are: potassium, magnesium, calcium and sodium. Among them there is a fine balance, which must be maintained for the correct functioning of the muscle cell and beyond. It may happen that this balance is altered. Consequently, the impulse of contraction is also modified and tachycardia occurs. ventricular. The main ionic / electrolyte imbalances are:
- Hypokalaemia, or hypokalaemia.
- Hypocalcemia.
- Hypomagnesemia.
Other risk factors
There are risk factors that favor the onset of tachycardia episodes even in healthy subjects. These are special circumstances, such as severe trauma to the chest or the intake of certain drugs. A summary of the main risk factors is as follows:
- Taking medications:
- Tricyclic antidepressants.
- Cocaine abuse.
- Alcohol abuse.
- Smoke.
- Caffeine.
- Gas poisoning:
- Cyclopropane.
- Carbon monoxide.
- Trauma to the chest.
- Physical and emotional stress.
Symptoms and complications
Typical symptoms of ventricular tachycardia are:
- Palpitation, or heartbeat.
- Chest pain.
- Dyspnea.
- Dizziness.
- Fainting.
- Syncope.
- Shortness of breath.
Most patients have these symptoms in association with ischemic heart disease or heart disease that impairs blood flow (for example, heart valve disease).
Signs
The doctor may notice the following clinical signs:
- Accelerated pulse.
- Hypotension.
- Anxiety.
- Agitation.
- Loss of consciousness.
Their occurrence depends on the extent of the heart disease: the more severe it is, the easier it is for them to occur.
Complications
Ventricular tachycardia can degenerate into ventricular fibrillation. This occurs mainly in people with heart disease, while cases of paroxysmal ventricular tachycardia are very rare in healthy people.
Ventricular fibrillation usually has a fatal course. It determines the death of the patient:
- For sudden cardiac death.
- For cardiac arrest.
Diagnosis
Several investigations 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 to identify the form of ventricular tachycardia that afflicts a patient. It is also possible to monitor cardiac activity over 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 with sporadic and unpredictable onset.
Echocardiography
This is a non-invasive test. It uses ultrasound to assess the health of the main structures of the heart: atria, ventricles and valves. It is useful when valvular disease is suspected.
Chest X-ray
Provides information on the relationship between the heart and lungs. At the origin of a ventricular tachycardia there may 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 the origin of ventricular tachycardia is ischemic heart disease. Measure the location and degree of occlusion of the coronary arteries to plan for possible surgery. This is a delicate test, as there is a risk of damaging the coronary vessels crossed by the catheter.
Blood tests
They provide different information on:
- Concentrations of ions / electrolytes:
- Calcium Levels
- Levels of magnesium
- Levels of phosphate
- Concentration of some drugs taken by the patient.
- Concentration of some cardiac markers.
Therapy
A premise: when heart disease is the origin of ventricular tachycardia, the goal of treatment is twofold:
- Resolve the underlying heart disorder. Primary goal.
- Resolve the arrhythmic disorder. Secondary objective.
This is explained by the fact that the second problem is a consequence of the first.
"Healthy" patients with sporadic tachycardia
In those without heart disease, ventricular tachycardia can resolve spontaneously. Thus, the administration of drugs can be avoided. In any case, it is advisable to consult a doctor and undergo in-depth investigations.
"Healthy" patients with sustained or persistent tachycardia
If the patient has numerous sustained episodes, to block the tachycardia attack, the following can be used:
- 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 the heart rate.
Electrical cardioversion consists of:
- Electric shock to reset and restore normal sinus rhythm. It uses 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 correct electrical shock. The other great advantage is that they can be used by non-medical personnel.
Cardiopathic patients or patients with other pathologies
Drug therapy is the same as described above. Therefore:
- Antiarrhythmics
- Beta blockers.
To these are added:
- Anticoagulants, to avoid the formation of thrombi and emboli, due to valvulopathies.
In addition to electrical cardioversion, it is possible to intervene surgically with:
- Catheter radiofrequency ablation. Through a catheter conducted to the heart, a radiofrequency discharge is infused into 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 electrodes, which emit an electric shock when they feel an abnormal increase in heart rate. They have a duration of 7-8 years, after which they must be replaced. A possible problem may be due to a malfunction of the appliance, which can emit unsolicited electric shocks.
Obviously, the therapy to be adopted must be chosen on a case-by-case basis, without forgetting that the first therapeutic intervention must resolve any pathological problem that generates ventricular tachycardia. Below is a table summarizing the possible therapy.
- Amiodarone
- Lidocaine
- Procainamide
- Amiodarone
- Lidocaine
- Procainamide
Anticoagulants.
Prevention
Adopting a healthy lifestyle is the best prevention. Therefore:
- Stop smoking.
- Limit alcohol consumption.
- Change your diet.
- Do not use drugs.
- Exercise.
Tobacco and alcohol are responsible not only for sporadic episodes of tachycardia, but also for chronic alterations of the heart rhythm. They are, in fact, among the most common risk factors in the development of heart disease.
Changing your eating habits is another fundamental preventive step. It is advisable to reduce fat, red meat and increase the consumption of fruits and vegetables.
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 have pathological conditions, such as hyperlipidemia, hypertension and diabetes. These favor the development of heart disease.
- They have a family history of coronary heart disease.
- Smokers.
- Alcoholics.
