Extrasystole

Physiopathology

The normal cardiac contraction comes from a depolarization (inversion of the electric polarity of the cellular membrane) cyclic of a group of cells located on the high part of the right auricle, the sinusal Nœud. This depolarization is propagated with the whole of the heart and involves, on the level of the muscular cells, a contraction of these last. It is followed by a refractory period , brief moment when the cells are not any more stimulables. The cardiac rhythm is thus controlled by this node.

This depolarization can sometimes result from another place that the sinusal node. It comes then from another part of the auricle S, fabric of conduction (nervous system clean called cardionector of the heart) or of the Ventricule S. If this depolarization occurs apart from the refractory period, it is transmitted, gradually, to all or is left the heart, involving an additional contraction, constituting the extrasystole. It is thus the result of an increased electric exitability of a well delimited zone of the cardiac muscle.

According to the cardiac cavity where the premature contraction of muscle fibers takes place (auricle, Ventricule or junction between these two cavities), one will speak about auricular extrasystoles (ESA), ventricular extrasystoles (ESV) or jonctionnelles extrasystoles. The auricular and jonctionnelles extrasytoles, of aspect and close causes, are connected under the term of supra-ventricular extrasystoles .

The generated contraction is not always effective: if a ventricular extrasystole occurs too much advances some, it arrives whereas this cavity is filled little: the resulting contraction has in this case only one effectiveness reduced, even null on the cardiac Débit: it can thus be visible on the electrocardiogram which visualizes the electric operation of the heart, but on the other hand, directly invisible on the curves of pressure, or, in a simpler way, with the palpation of the Pouls.

The extrasystole is sometimes followed by a short pause, the compensatory leave . This last has as a consequence an improved cardiac filling. The following contraction is thus more effective, stronger. It is the latter which is felt at the time of palpitations and not the extrasystole.

Diagnosis

Private clinic

They can be asymptomatic (the patient does not complain about nothing). The subject can feel Palpitations, a feeling of " pause" cardiac.

The catch of Pulse and the cardiac Auscultation (prolonged) can find a rate/rhythm which seems irregular.

Complementary examinations

ECG makes it possible to visualize the extrasystole. From his aspect, one can deduce his localization from it.
the electrocardiogram of effort makes it possible to evaluate the influence of stimulation Adrénergique on the extrasystolie.
the holter-rhythmic makes it possible to quantify the extrasystolie, to specify the characteristics and their repetition of it.

Causes

It is normal to have some extrasystoles per day. Their number increases with the age and it is usual to count, for example, nearly 1000 extrasystoles auriculaires/24h in an octogenarian without that have any significance.

The causes are multiple. One can find:

a Cardiopathie: myocardic Ischaemia , Myocarditis, hypertrophic Cardiomyopathie dilated or , myocardic Contusion , Prolapsus of the mitral valve,
a metabolic disorder: a Hypokaliémie (potassium deficit in blood), a Hypoxia (oxygen deficit),
a disease endocrinienne,
a medicamentous cause (Iatrogénie): Digitalique S, Theophylline, tricyclic antidepressants, drugs sympathomimetic S for example,
a catch of exciting: Coffee, The, alcohol, Cocaine, Amphetamine S…
a acute Infection,
following a great physical effort.

Auricular extrasystoles (ESA)

ECG

One finds a premature wave P which can be of different form (sometimes intricate in the wave T of the preceding complex), followed, or not, of a complex QRS.

In the absence of wave QRS, one then speaks about blocked auricular extrasystole .

The QRS can be normal. It sometimes abnormal, is widened. One speaks then about auricular extrasystole with aberration of conduction .

Treatment

It is before all that of the cause when it is identified. For the treatment of the disorder of the rate/rhythm itself, it depends on the ground, the caused embarrassment and the existence or not of a subjacent cardiopathy:

a extrasystolie isolated on healthy and asymptomatic heart must be the subject of a simple monitoring, without treatment.
Extrasystoles isolated and symptomatic occurring on a healthy heart:

hygiéno-dietetic rules (reduction or suppression of exciting for example), sometimes associated with a Sedative of the type Anxiolytique,
if that is not enough, one discusses an anti-asynchronous treatment: Beat-blocking S, Quinidinique S more rarely or drugs of class Ic (Flécaïnide, Cibenzoline or Propafénone, and in last spring, the Amiodarone.

In the event of Cardiovascular diseases, one uses Antiarythmique S (Ia classes or Ic), more or less associated with a treatment Anticoagulant by antivitamines K or plate Antiagrégant,
In the event of Cardiopathie advanced with deterioration of the contractile function of the left Ventricule, the Amiodarone is recommended.

Ventricular extrasystoles (ESV)

In term diagnoses what imports is to know if the ventricular extrasystolie presents or not signs of gravity being able to lead to a ventricular Tachycardie, with then the need for introducing a treatment Antiarythmique.

ECG

One finds a complex QRS not preceded by (or without fixed chronological relation with) a wave P. complex QRS typically broad (superior with 0,12 S.) and is deformed compared to basic complexes QRS with aspect either of Bloc of branch right if it is about a ventricular extrasystole being born from the left Ventricule, or of block of left branch if it is about a ESV incipient from the right Ventricule. The repolarization is reversed with a negative wave T.

Prognostic elements

the morphology (form) of the ESV: when all the extrasystoles have the same aspect, they are known as monomorphes . When they have different forms, they are known as polymorphic (existence of several hearths ectopic): they are then potentially more serious.
the interval of coupling: the coupling of an extrasystole compared to preceding complex QRS is known as court when the ESV occurs at the top of the wave T the preceding one (early extrasystole or phenomenon R/T ).
the number of ESV by 24:00,
Their rate/rhythm:

one speaks about doublet (2 ESV of continuation), of triplet (3 ESV of continuation); beyond, one speaks about salvo of ESV or ventricular Tachycardie nonconstant.
they can be bigéminées (a ESV after each normal complex), or trigéminées (1 ESV all 2 normal complexes).

Gravity

It is primarily defined by:

the existence of a subjacent Cardiopathie and especially by the deterioration of the systolic function quantified by the Fraction of ejection.
occurred of a syncope without another explanation, of a ventricular Tachycardia.

Certain criteria rest on the aspect of the extrasystoles:

the precocity of the ESV (near to the wave T),
the polymorphic aspect,
the presence of several repetitive complexes (doublets, triplets, salvos), especially if these forms appear with the effort.

It is noted that the number of extrasystoles, taken separately, is not to in no case a criterion of gravity.

Can thus be regarded as benign the ESV on healthy heart, monomorphes, of great amplitude, without repetitive form, decreasing or disappearing with the effort.

Must be regarded as potentially serious, and justifying then a treatment Antiarythmique, the ESV very premature (or early), repetitive (occurring in doublets, triplets even salvos of ventricular Tachycardie), polymorphic, with very widened QRS and of low amplitude, worsening with the effort, especially if they occur on a pathological heart.

The principal risk of the ESV is to induce a ventricular arrhythmia more severe than it is of a ventricular Tachycardie or a ventricular Fibrillation with risk of sudden death. The ventricular extrasystole will be the " gâchette" inducing the starting of a constant arrhythmia.

Treatment

It aims to avoid the Sudden death, and incidentally, to improve quality of life by decreasing the functional embarrassment.

the benign and asymptomatic ESV do not require any treatment.
ESV benign:

hygiéno-dietetic rules (reduction or suppression of exciting), more or less associated with a Sedative treatment of the type Anxiolytique,
in the event of important functional embarrassment, use of some Antiarythmique S.

ESV:

treatment of the cause when this one is identified: Cardiopathie subjacent, starting or supporting factor (Hypokaliémie, stop of a treatment of which one suspect the arythmogene effect),
medicamentous treatment: Antiarythmique S, Beat-blocking S, Amiodarone, inhibiting calcic.

Jonctionnelles extrasystoles

They appear on the ECG by a complex QRS premature, not preceded by a wave P (contrary to the auricular extrasystoles). They are causes close to the auricular extrasystoles their treatment in is similar.

External bond

Site E-Cardiology: the extrasystoles

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