Asystole (cardiac arrest) is characterized by the cessation of the heart muscle. The atria and the ventricles of the heart stop and not contract, the result is stopping of the blood flow through the bloodstream. Ventricular complexes disappear on ECG in case of asystole. Asystole may be instantaneous and the ensuing after arrhythmias.
In the first case, with the background of well-being and the absence of cardiac arrhythmias, heart suddenly loses electrical excitability that resembles a short circuit. The more often reason for this is acute ischemia of the heart, the appearance of which is caused by obesity, smoking, diabetes and hypertension.
In the second case, with long flowing state of fibrillation (uncoordinated, fragmented contractions of cardiac muscle fibers), rapidly circulating irregular electrical impulses occur, that disrupt blood flow in coronary vessels and, ultimately, disrupt the possibility of the heart to contract, causing its stop.
Precisely the ventricular asystole (full stop of the ventricular contractions), unlike atrial asystole, compatible with the life, leads to the death of the patient.
- conduction disorders with a parallel inhibition of the ability of the ventricles to contract rhythmically. Most often this condition may be the result of atrial fibrillation or ventricular fibrillation and comes after them. In some cases the ventricular asystole is provoked by the electromechanical dissociation or ventricular tachycardia.
Atrial asystole is the absence of electrical and mechanical atrial systole during one or more cardiac cycles. Unlike ventricular asystole, isolated atria asystole does not lead to cardiac arrest because of emergence of substitutive rhythm from the atrioventricular node or rare idioventricular rhythm.
Atrial asystole (atrial arrest) is connected with the complete suppression of the activity of the sinus node or sinoatrial block, lack of heterotopic excitation focuses in the atrial myocardium and the lack of retrograde conduction from the ventricle to the atria. Centers of automaticity of lower orders assume the role of pacemaker. There is a so-called node (atrioventricular) or ventricular (idioventricular) rhythm. Accurate detection is difficult: there are no P waves, wave of atrial flutter or atrial fibrillation on the ECG. In cases of doubt intraatrial ECG is recorded.