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Commotio cordis can occur only upon impact within a narrow window of about 40 milliseconds in the cardiac electrical cycle, explaining why it is so rare. [ 1 ] If cardiopulmonary resuscitation (CPR) combined with the use of an on-site automated external defibrillator is employed within three minutes of the impact, survival from commotio cordis ...
Defibrillation is often an important step in cardiopulmonary resuscitation (CPR). [6] [7] CPR is an algorithm-based intervention aimed to restore cardiac and pulmonary function. [6] Defibrillation is indicated only in certain types of cardiac dysrhythmias, specifically ventricular fibrillation (VF) and pulseless ventricular tachycardia.
Cardiac cells have two refractory periods, the first from the beginning of phase 0 until part way through phase 3; this is known as the absolute refractory period during which it is impossible for the cell to produce another action potential. This is immediately followed, until the end of phase 3, by a relative refractory period, during which a ...
Ectopic beat is a disturbance of the cardiac rhythm frequently related to the electrical conduction system of the heart, in which beats arise from fibers or group of fibers outside the region in the heart muscle ordinarily responsible for impulse formation (i.e., the sinoatrial node).
Some clinicians may attempt to defibrillate fine V-fib in the hope that it can be reverted to a cardiac rhythm compatible with life, whereas others will deliver CPR and sometimes drugs as described in the advanced cardiac life support protocols in an attempt to increase its amplitude and the odds of successful defibrillation. [citation needed]
These pathways can lead to abnormal heart rhythms (arrhythmias) associated with symptoms of palpitations. Some pathways may activate a region of ventricular muscle earlier than would normally occur, referred to as pre-excitation, and this may be seen on an electrocardiogram .
The conduction system consists of specialized heart muscle cells, situated within the myocardium. [3] There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow.
Occasional P waves and QRS complexes can be seen on the electrocardiogram. The complexes tend to be wide and bizarre in morphological appearance. [1] Clinically, an agonal rhythm is regarded as asystole and should be treated equivalently, with cardiopulmonary resuscitation and administration of intravenous adrenaline. [2]