What are the electrocardiographic (ECG) manifestations of cardiac arrest?
Sep 14, 2023
Source: Cainiu Health
Dr. Wang Xin
Introduction
In general, there are four main electrocardiographic manifestations of cardiac arrest: asystole, pulseless electrical activity (electromechanical dissociation), ventricular fibrillation, and pulseless ventricular tachycardia. When patients experience symptoms of discomfort, it is recommended to seek timely medical evaluation and appropriate treatment. In the event of cardiac arrest, chest compressions and artificial respiration should be performed to maintain circulation of blood within the patient's body.
Generally speaking, there are four main electrocardiographic (ECG) manifestations of cardiac arrest: asystole, pulseless electrical activity (PEA), ventricular fibrillation, and pulseless ventricular tachycardia. When patients experience physical discomfort or symptoms, it is recommended to seek timely medical evaluation and appropriate treatment. The specific classifications are as follows:
1. Asystole
Asystole refers to the complete loss of electrical activity in the myocardium, appearing as a flat line on the ECG. Common causes include failure of sinus, atrial, or junctional impulses to reach the ventricles, combined with an inability of intrinsic ventricular pacemakers to generate impulses. In such cases, immediate cardiopulmonary resuscitation (CPR) should be initiated, along with emergency medications such as phenylephrine hydrochloride injection, dopamine hydrochloride injection, and atropine sulfate injection. Endotracheal intubation and mechanical ventilation may be required if necessary.
2. Pulseless Electrical Activity (PEA)
Pulseless electrical activity refers to the presence of organized or semi-organized electrical activity on the ECG without effective mechanical contraction or palpable pulse. The ECG typically shows an isoelectric baseline with normal or wide, bizarre, low-amplitude QRS complexes at a rate usually below 30 beats per minute. This condition represents mechanical cessation rather than electrical silence and carries an extremely high mortality rate. Immediate CPR must be initiated when this pattern occurs.
3. Ventricular Fibrillation (VF)
Ventricular fibrillation, commonly abbreviated as VF, is characterized on the ECG by the absence of identifiable QRS complexes, replaced by irregular undulations of varying amplitude and morphology, with a frequency of approximately 200–400 beats per minute. Patients with VF require immediate defibrillation, along with aggressive management of underlying conditions that triggered the arrhythmia.
4. Pulseless Ventricular Tachycardia (PVT)
Pulseless ventricular tachycardia is a common presentation of cardiac arrest. It occurs when myocardial contractility is severely impaired, leading to loss of consciousness. On ECG, it appears as rapid ventricular tachycardia with wide and bizarre QRS complexes; however, no pulse can be detected, indicating ineffective cardiac contractions. Treatment includes CPR, antiarrhythmic therapy, and prompt defibrillation when indicated.
When a patient experiences cardiac arrest, chest compressions and rescue breathing must be performed immediately to maintain circulation within the heart. Alternating hand compressions on the chest help sustain vital signs and may restore spontaneous cardiac rhythm. At the same time, emergency medical services (e.g., dialing 120) should be activated immediately, and defibrillation should be performed if available.
