In terms of position in the cardiac cycle, ventricular extrasystoles are premature ventricular depolarizations, which originates from a source which is located distal to the bifurcation of His fascicle.
- On a healthy heart, ventricular extrasystoles occur in the following situations: excessive consumption of coffee, tobacco abuse, emotions, stress;
- On a diseased heart: coronary artery disease, cardiomyopathy, mitral regurgitation, left ventricular arrhythmogenic dysplasia;
- Iatrogenic, ventricular extrasystoles appear: in digoxin toxicity, after initiation of fibrinolytic therapy in myocardial infarction and in hypokalaemia.
The diagnosis of ventricular extrasystoles is based on the symptoms, on the physical examination and on the ECG interpretation.
Symptoms include palpitations, chest discomfort, feeling of heart stopping, followed by a stronger beat, faintness, syncope.
Physical examination may reveal the following: can be collected an early beat, which is followed by a pause (compensatory pause). In case of frequent ventricular extrasystoles, hypotension may occur.
ECG shows the following:
- Early QRS complex with abnormal configuration and an increased length, which are not preceded by P waves and are followed by ST segment with a T wave which is opposite to the QRS complex. Right ventricular extrasystoles, are generally look like left bundle branch block and left ventricular extrasystoles have the appearance of right bundle branch block.
- The interval between ventricular extrasystoles and the previous QRS complex is constant (fixed coupling interval).
- Post ventricular pause is usually fully compensatory, rarely are interpolated ventricular extrasystoles.
The degree of premature ventricular extrasystoles is variable and can occur at any time in the diastole. Sometimes it is a very short coupling interval which will make that the ventricular extrasystoles to be registered on top of previous T wave, a phenomenon name by the R / T term. In these circumstances there is the danger of triggering a ventricular fibrillation.
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Ventricular extrasystoles can be:
- Unifocal, QRS morphology is identical in all leads;
- Polifocal, QRS morphology is different in ECG leads, which means that the QRS complexes originate in one or more ectopic outbreaks;
- Isolated, characterized by the occurrence of a single ventricular extrasystole;
- Systematized: the appearance of two or more ventricular extrsistoles under the form of bigeminy, trigeminy, etc..
Based on Holter monitoring, Lown proposed the following classification of ventricular extrasystoles:
- Class 0: absence ventricular extrsistoles at least 3 hours;
- Class I: premature ventricular extrasistoles, monomorphic and occasional, the occurrence is less than one ventricular extrasistole per minute or less than 30 ventricular extrasystoles per hour.
- Class II: frequent monomorphic ventricular extrasystoles, more than one ventricular extrasistole per minute or more than 30 ventricular extrasystoles per hour.
- Class IIIa: polymorphic ventricular extrasystoles (multifocal).
- Class IIIb: systematized ventricular extrasystoles (bigeminy, trigeminy).
- Class IVa: coupled repetitive ventricular extrasystoles (2 ventricular extrasystoles).
- Class IVb: repetitive triplets of ventricular extrasystoles (3 ventricular extrasystoles).
- Class V: R/T phenomena.
Ventricular extrasystoles that appear on a healthy heart require the removal of trigger factors and in the case of important symptoms, is recommended the administration of beta blockers and sedatives.
In the case of organic ventricular extrsistoles, the treatment is based on the Lown classification, as follows:
- Classes I and II benefit from treatment of the disease that lead to the appearance of extrasistoles;
- Classes III, IV and V: monitoring, determining of pathological substrate, correcting electrolyte and acid-base disorders, myocardial ischemia and other factors incriminated that are causing the ventricular extrasistoles. Administration of beta blockers, amiodarone or lidocaine, all intravenously.