Tachycardia

The tachycardia is characterized by high frequency rate (above 100 per minute in a resting adult). It can be an announcement or consequence of cardiac or extracardiac diseases and also acquire a category of disease itself, often greater than 150 per minute. There are different medical classifications for this condition, including:

• Helical tachycardia
• Orthodromic tachycardia
• Monomorphic tachycardias
• Sinus tachycardia
• Ventricular tachycardia

They are very frequent, they constitute a public health problem in Cuba and throughout the world. They appear at any age and in both sexes, with variations according to the type of tachycardia.

Summary

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• 1 Ratings
  • 1 Classification of tachyarrhythmias
• 2 Clinical picture
• 3 Diagnosis
• 4 Treatment
• 5 Complications associated with the procedure
• 6 See Also
• 7 Sources
• 8 Bibliography
• 9 External links

Classifications

Classification of tachyarrhythmias

• Supraventricular tachycardias

Sinus plane

• Appropriate sinus tachycardia or physiological.
• Inappropriate or pathological sinus tachycardia.
• Sinoatrial reentry.

Pure ear plane

• Atrial fluter type I and II.
• Ectopic atrial tachycardia.
• Multifocal atrial tachycardia.

AV Union map

• Paroxysmal tachycardia due to nodal reentry.

Common type Non-common type

• Circular motion atrioventricular tachycardia / accessory pathway

Orthodromic. Antidromic.

• Non-paroxysmal tachycardia of the AV junction.
• Ventricular tachycardias

According to its electrocardiographic aspect

• Ventricular extrasystoles.
• Monomorphic ventricular tachycardia.
• Polymorphic ventricular tachycardia.
• Torsade de pointes.
• Ventricular flutter.
• Ventricular fibrillation

According to the base pathology

• In ischemic pathology.
• In dilated cardiomyopathy.
• In hypertrophic cardiomyopathy.
• In right ventricular dysplasia.
• In special situations (electrolyte disorders, pro arrhythmic effect of FAA).
• In systematic diseases (amyloidosis, sarcoidosis).
• In Chagas disease.
• In congenital or acquired long QT syndrome
• Idiopathic
• Ventricular tachycardia of the right ventricular outflow tract.
• Fascicular ventricular tachycardia.

TSVs NOT ASSOCIATED WITH THE WPW SYNDROME Here are included:

• Atrial tachycardia (multifocal and unifocal)
• Paroxysmal regular tachycardias (including the

intranodal tachycardia (TRIN)

• Tachycardia mediated by a hidden accessory pathway with properties of

Kent’s beam-type fast conduction) Mediated by a hidden accessory path of slow and decremental conduction (Coumel’s tachycardia)

All of these forms of tachycardia have in common that:

• They have organized atrial activation and QRS morphology.

during tachycardia similar to that of sinus rhythm, which is generally a narrow QRS (<0.08 s), except in cases where functional blockade of a branch of the bundle of His occurs.

• They are different in the substrate and arrhythmogenic mechanism, which determines

its clinical presentation and response to treatment.

Atrial tachycardia Definition The ECG is characterized by well-defined P waves, at a frequency between 100 and 240 per min, this is usually different in amplitude and electrical axis from the sinus P wave. The conduction to the ventricles can be 1: 1 or present a variable degree of nodal block 2: 1, 3: 1, etc. Using MSC or Valsalva maneuvers, atrial and ventricular activity can be dissociated (producing 2: 1, 3: 1 block) without interrupting tachycardia. The PR interval is less than the RP interval, and can be equal to, greater than, or less than the PR interval in sinus rhythm. The QRS has a morphology similar to that of the sinus rhythm, although in tachycardias with a rapid ventricular response it can present branch block type aberrance.

• Multifocal TA.
• Monomorphic or unifocal TA.

TA multifocal Features

• At least three different P wave morphologies are identified (not counting the sinus P wave).
• Its frequency is greater than 100 per min.
• PP intervals are usually irregular.
• The ventricular response is usually variable: 1: 1, 2: 1, 3: 1, etc., and the PR and RR intervals as well.
• More than 95% of multifocal atrial tachycardias are associated with decompensated COPD and / or IC.
• The episodes last for several days and alternate with AF crises and paroxysmal FlA.
• The precipitating factor is a decompensation of the underlying pathology, and

facilitates with:

• Hypoxia
• High values ​​of theophyllinemia and ß-stimulants
• Presence of hypokalemia, hypomagnesemia, or hypocalcemia

Monomorphic or unifocal TA Features

• A single P wave morphology is identified, which is different from the P wave of sinus rhythm in amplitude and electrical axis.
• Its frequency usually ranges between 100 and 240 beats / min.
• Clinically they have two forms of presentation: Paroxysmal and Incessant.

Regular paroxysmal tachycardias with narrow QRS verapamil / adenosine sensitive Definition They are tachycardias mediated by a reentry mechanism in which the AV node participates as an arm of the circuit , making them sensitive to verapamil and adenosine. The frequency ranges between 120 and 250 per min, (average between 160-180). Two types with different mechanisms are distinguished:

Intranodal tachycardia (TRIN) The arrhythmogenic mechanism is a reentry into the AV node. The functional substrate is the presence of dual-path nodal physiology. The A: V ratio is usually 1: 1. From an electrophysiological point of view, two forms are distinguished depending on the conduction velocity of each of the nodal pathways and the direction in which they are traveled by the activation front of the tachycardia:

• TRIN (90%): slow / fast: the stimulus is conducted through the slow path in

down and fast track up.

• Uncommon TRIN (10%): fast / slow: the stimulus is conducted by the pathway

fast downward and slow downward. Slow / Slow: The stimulus is driven down and up two ways with slow driving speed. Orthodromic tachycardias (OT) mediated by hidden accessory pathway

Incessant tachycardia of the AV junction (Coumel’s tachycardia) Definition They are SVT mediated by a hidden accessory pathway with slow and decremental conduction velocity. Anatomically they have a posteroseptal location and tend to be incessant. Its frequency ranges from 100 to 240 per min. Its diagnosis is usually made in the course of a routine examination or in a tachycardiomyopathy phase.

Orthodromic tachycardia (OT) if during it ventricular depolarization is performed through the specific conduction system (anterograde arm and the accessory pathway as retrograde arm of the circuit). This is the most frequent modality in the clinic.

Antidromic tachycardia: when the accessory pathway is used as an antegrade arm and the specific system as a retrograde arm.

Clinical picture

Some patients perceive it and describe it very well (“runaway” heart, “fluttering” of a pigeon ), they specify whether it is ordered, its abrupt or progressive onset, the triggering factors. Others do not perceive it in itself, but refer to the symptoms that it usually causes (shortness of breath, chest pain, dizziness, sweating, paleness, decay, loss of consciousness) .It is absolutely variable, occurs only occasionally or several times when day. It lasts seconds or hours, and can even become incessant. It ends spontaneously or measures are required to stop it.

Tachycardia is often associated with arrhythmia but these are not synonyms. Arrhythmia is any heart rhythm different from normal, due to alteration in the origin of the impulse in the heart, its frequency, regularity or conduction. There is a great diversity of arrhythmias, and within them are tachycardias.

Diagnosis

Tachycardia is not an isolated problem. In her diagnosis, everything is important: the patient’s interrogation, her physical examination, routine analyzes, stress tests and especially the sequence of electrocardiograms. Direct investigation of the heart’s electrical system using catheter-electrodes has precise indications and is carried out in specialized services (in Cuba, at the Institute of Cardiology and Cardiovascular Surgery ). Among the organic cardiac disorders that can cause it are: ischemic heart disease, diseases of the heart muscle or its valves, congenital diseases, growths of the heart; and extracardiac: hyperthyroidism, lupus erythematosus, neurological diseases. It also originates from transitory alterations or in subjects without organic problems.

Differential diagnosis

• Surface ECG analysis during tachycardia, performed in

basal conditions and / or after maneuvers that modify AV conduction, such as MSC or adenosine administration. This analysis is based on evaluating the relationship between atrial and ventricular frequencies, and the morphology and location of the P wave with respect to the QRS (PR / RP interval).

• The EEF completes the diagnostic evaluation but, as it is a test

invasive, it is only indicated in cases in which treatment by radiofrequency ablation is considered. With the exception of multifocal atrial tachycardias, the vast majority of these tachycardias are not associated with organic heart disease.

• A control echocardiogram is recommended for all patients,

especially to children and young people, due to a possible association with congenital heart defects such as Ebstein’s disease, mitral prolapse or hypertrophic cardiomyopathy, etc.

The mechanisms of tachycardias are complex, their prognosis and the behavior to follow are diverse. Only careful analysis by the doctor leads to the wisest decision. Some important things remain in the patient’s hands: going to the doctor, keeping the electrocardiograms as a valuable story; Do not start, suppress, or modify antiarrhythmic doses at will. The patient with tachycardia should know that large windows have been opened for diagnosis and treatment to improve or cure it. In Cuba, these possibilities are available to anyone who requires them.

Treatment

Some tachycardias endanger the patient’s life, lead to severe symptoms and require emergency treatment or to prevent new episodes. Others do not require treatment (which could be more harmful than beneficial). Sometimes it will be necessary to treat the disease causing the tachycardia and not the tachycardia itself.

There are treatments with antiarrhythmic drugs. Surgery has been used in the recent past, but nowadays the main role of healing is ablation with radiofrequency (destruction of the base of the arrhythmia with high-frequency alternating currents) .It is not a surgical procedure, it has a high success rate and rare complications, and avoids the patient’s attachment to antiarrhythmics. Of course, your indications can only be handled by your doctor. There are also high-tech electronic devices to resolve some tachycardias.

Treatment modalities include:

Pharmacotherapy:

• Group IC antiarrhythmics (propafenone and flecainide)
• Amiodarone
• In cases where tachycardia is shown to be sensitive to catecholamines, β-blockers.

Radiofrequency ablation:

• Monomorphic ATs without heart disease are selectively approachable at the origin of the tachycardia, regardless of the underlying arrhythmogenic mechanism. However, one limitation is the poor reproducibility by EEF of some of these tachycardias, especially those due to abnormal automatism.
• BP associated with organic heart disease is seldom feasible to address by selective ablation. Nonselective ablation of the AV node associated with definitive pacemaker implantation is proposed in cases where pharmacological treatment fails, either relapse prevention or ventricular rate control (with the same drugs and assumptions made in multifocal tachycardias). .

Evaluation and treatment of the asymptomatic patient

• This type of arrhythmia is usually diagnosed by routine ECG.
• The absence of symptoms until the time of diagnosis is not a

guarantee of the safety of the accessory road.

• Sudden death, although infrequent, may be the first manifestation of

the illness.

• The performance of an EEF is not justified for the sole purpose of knowing the

location and electrophysiological properties of the pathway, without resorting to ablation in the same procedure.

• Prophylactic antiarrhythmic treatment is not indicated in the patient.

asymptomatic, in the same way that the restriction of habitual activities does not seem necessary either.

• It is recommended to avoid high level competitive sports practice.

Complications associated with the procedure

• Serious: they are infrequent:

– Lock AV (medioseptales tract and septal parahisianas later).
– Systemic embolism

• Minor complications

– They are related to arterial and venous punctures (hematomas and venous thrombosis). Mortality is 0.2%.

• Others

-The factors associated with the appearance of major complications are the presence of structural heart disease and multiple targets in the ablation procedure.
– The duration of the procedure and the experience of the team that performs it are also determinants of the success and rate of complications, which makes it advisable that the ablation be carried out in specialized centers and by experienced electrophysiologists.