Tachycardia is a heart rhythm disorder that involves the appearance of an accelerated pulse of over 100 beats/minute. The increase in heart rate that exceeds this value and does not present an obvious physiological cause such as fast walking, intense physical effort or stress, indicates the existence of a tachycardia with a pathological substrate that requires investigations and specialized medical care for remission.
How does tachycardia manifest itself?
Management of risk factors as a measure to prevent tachycardia
The fast heartbeat prevents the atria and ventricles from filling with blood during diastole (the relaxation period of the heart between 2 successive beats) and causes a lack of oxygenation at the cerebral level with the appearance of vertigo (dizziness) and sometimes loss of consciousness or blood deprivation of the coronary arteries with the occurrence of acute cardiac ischemia.
Tachycardias can be of short duration or they can develop chronically, causing the occurrence of life-threatening complications (acute myocardial infarction, stroke) if they are not treated properly.
Causes tachycardia
The causes that frequently cause the appearance of ventricular and atrial tachycardia involve the disturbance of the electrical impulses of the heart and are represented by:
- Congenital cardiac malformations that may involve structural defects with or without cyanosis, functional defects of the heart and positioning defects of the heart, including tetralogy of Fallot, prolonged QT syndrome, valvular malformations
- Acute or chronic heart diseases – myocardial infarction, dilated cardiomyopathy, hypertrophic or restrictive cardiomyopathy, myocarditis (inflammation of various etiologies of the heart muscle), mitral valve diseases, congestive heart failure and more
- Anemia – tachycardia in people with low erythrocyte hemoglobin is a compensatory mechanism by which the body maintains the appropriate oxygenation of the tissues by increasing the number of heartbeats/minute
- Hypertension or hypotension
- Febrile syndrome
- Hyperthyroidism (hyperfunction of the thyroid gland)
- Hydro-electrolytic imbalances that include sodium, potassium, calcium and magnesium involved in the physiology of cardiac muscle contractility
- Smoking, excessive consumption of stimulants or alcohol and the use of substances (especially methamphetamine) are other important risk factors for tachycardias related to the patient’s inappropriate lifestyle. Obesity, sleep apnea syndrome, diabetes and chronic lung diseases are pathologies that can cause heart rhythm disorders such as tachycardia in their evolution
Types of tachycardia
Tachycardias can be classified according to their location in the different chambers of the heart (atria or ventricles) as follows:
- Atrial Fibrillation
- Atrial flutter
- Supraventricular tachycardia
- Ventricular tachycardia
- Ventricular fibrillation
Atrial Fibrillation
Atrial fibrillation is characterized by a very fast and irregular pulse generated in the upper chambers of the heart represented by the atria. The electrical impulses that determine the occurrence of atrial fibrillation are formed at the level of an abnormal focus and cause a chaotic contractile activity of the atria with an increase in the risk of acute heart failure and cerebral vascular accidents. Atrial fibrillation, in turn, can be paroxysmal with a short duration of evolution and spontaneous remission, persistent with a duration of more than 7 days that requires treatment and permanent, with a long evolution of over 1 year.
Atrial flutter
Atrial flutter is manifested by the appearance of a fast, regular pulse generated at the atrial level and can be paroxysmal (an episode that lasts several hours or days) and persistent (permanent). In most situations, the spontaneous evolution of atrial flutter involves chronicity and increases the risk of brain ischemia (strokes).
Supraventricular tachycardia
Supraventricular tachycardia develops with a rapid pulse generated at the level of the cardiac tissue located above the ventricles and is frequently manifested in patients who associate congenital heart malformations.
Ventricular tachycardia
Ventricular tachycardia affects the lower chambers of the heart represented by the 2 ventricles and originates distally from the Hiss bundle at the level of the active ventricular myocardium or the distal conduction network. In certain situations, ventricular tachycardia can be idiopathic (of unknown cause) or paradoxical, it can be due to arrhythmogenic medication or the one used in weight loss treatments based on ephedrine.
Ventricular fibrillation
Ventricular fibrillation is a severe heart rhythm disorder that constitutes a medical emergency due to the risk of generating complications represented by acute myocardial infarction. During this type of tachycardia, the ventricles contract inefficiently and chaotically generating in certain situations even 350 beats/minute with the considerable reduction of the heart’s pumping function. As a result, the volume of ejected blood decreases and tissue hypoxia occurs in different regions of the body. Ventricular fibrillation is the most common cause of sudden cardiac death.
Sinus tachycardia
Sinus tachycardia is an increase in the number of heartbeats per minute, often due to anxiety states or intense physical exercises, but it can also be caused by fever or the administration of certain types of drugs. If the sinus tachycardia has no obvious etiology, it is considered to be inadequate sinus tachycardia. In turn, sinus tachycardia can be of atrial, junctional or ventricular type depending on the cardiac structures at which it occurs.
How does tachycardia manifest itself?
The symptomatology that makes up the evolving clinical picture of tachycardia is represented in most situations by:
- Palpitations perceived by the patient as rapid heartbeats, of increased intensity
- Chest pain
- Syncope (loss of consciousness)
- Dizziness
- Rapid pulse
- Dyspnea (breathing difficulties)
- Painful discomfort in the chest that does not subside within 20 minutes of its appearance, severe dyspnea and loss of consciousness are symptoms that require cardiological evaluation as quickly as possible
Tachycardia treatment
Tachycardia treatment has the main purpose of restoring the physiological heart rhythm and can include:
- Performing vagal maneuvers to restore the patient’s physiological heart rate
- Medicinal cardioversion by administering beta-blockers or calcium channel blockers
- Electrical cardioversion by applying electric shocks to the anterior chest with the help of a defibrillator
- Ablation – minimally invasive surgical intervention through which the cardiologist uses radiofrequency energy to destroy the tissue from which aberrant electrical impulses are emitted, which cause tachycardia
- Pacemaker – subcutaneous implantation of a device with the role of modulating cardiac electrical activity, capable of emitting electrical shocks of reduced intensity to regulate contractile activity
- Surgical intervention to create scar tissue by making calculated incisions in the heart muscle. The formation of scar tissue prevents the transmission of aberrant electrical impulses and reduces the risk of tachycardia
- The classical surgical interventions for the extensive excision of the myocardial tissue at the level at which the aberrant electrical impulses are generated are reserved for patients with an unsatisfactory therapeutic response after the initiation of the other previously mentioned types of treatment. Open heart surgeries can also be used to treat tachycardias that occur after an acute myocardial infarction that requires coronary bypass surgery or in patients who associate ventricular aneurysms or heart valve diseases
Management of risk factors as a measure to prevent tachycardia
The appropriate management of the risk factors that predispose to the occurrence of tachycardias can be achieved by following a set of general recommendations regarding the patient’s lifestyle, which include:
- Adopting a balanced and healthy diet that prevents the development of atherosclerotic processes that cause cardiac ischemia
- Avoiding sedentarism by performing regular physical exercises
- Stopping smoking and drinking alcohol in large quantities
- Avoiding daily stress at work or in the family as much as possible
- Compliance with the schedule of medical visits recommended by the cardiologist and the treatments prescribed by him for the treatment of already-diagnosed heart conditions
References:
- Tachycardia, Cleveland Clinic – https://my.clevelandclinic.org/health/diseases/22108-tachycardia
- Tachycardia, Mayo Clinic – https://www.mayoclinic.org/diseases-conditions/tachycardia/diagnosis-treatment/drc-20355133
- Ventricular tachycardia: diagnosis of broad QRS complex tachycardia, BMJ Journals – https://heart.bmj.com/content/86/5/579.short
