Sudden Cardiac Arrest and Sudden Cardiac Death

Chapter 19 Sudden Cardiac Arrest and Sudden Cardiac Death

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The subject of this chapter is the ECG recognition of life-threatening arrhythmias that cause cardiac arrest. By definition, cardiac arrest occurs when the heart stops contracting effectively and ceases to pump blood. The important and closely related topic of sudden cardiac death is also introduced.

Clinical Aspects of Cardiac Arrest

The patient in cardiac arrest loses consciousness within seconds, and irreversible brain damage usually occurs within 4 minutes, sometimes sooner. Furthermore, shortly after the heart stops pumping, spontaneous breathing also ceases (cardiopulmonary arrest). In some cases, respirations stop first (primary respiratory arrest) and cardiac activity stops shortly thereafter.

No heart tones are audible with a stethoscope placed on the chest, and the blood pressure is unobtainable. The patient in cardiac arrest becomes cyanotic (bluish gray) from lack of circulating oxygenated blood, and the arms and legs become cool. If the brain becomes severely hypoxic, the pupils are fixed and dilated. Seizure activity may occur.

When cardiac arrest is recognized, cardiopulmonary resuscitation (CPR) efforts must be started without delay. The latest (2010) recommendations for the general public in the initial basic life support treatment of a witnessed cardiac arrest involve an approach of effective, continuous chest compressions without interruption for mouth-to-mouth resuscitation (so-called hands-only resuscitation). These new recommendations (Box 19-1) are designed to improve the practice of resuscitation in untrained bystanders; they apply to adults, children, and infants but exclude newborns.

The guidelines do recognize that, in some circumstances, conventional CPR (with a 30:2 compression-to-breath ratio) may provide more benefit than hands-only CPR. Some examples of these circumstances include the following:

The specific details of CPR and advanced cardiac life support including intubation, drug dosages, the use of automatic emergency defibrillators (AEDs) and standard defibrillators, along with other matters related to definitive diagnosis and treatment, lie outside the scope of this book but are discussed in selected references cited in the Bibliography. This chapter concentrates on the particular ECG patterns seen during cardiac arrest and the clinical implications of these major abnormalities.

Basic ECG Patterns in Cardiac Arrest

The three basic ECG patterns seen with cardiac arrest were mentioned in earlier chapters. Cardiac arrest may be associated with the ECG patterns listed in Box 19-2.

The ECG patterns seen in cardiac arrest are briefly reviewed in the following sections, with emphasis placed on their clinical implications (Figs. 19-1 to 19-6).

Jun 11, 2016 | Posted by in CARDIOLOGY | Comments Off on Sudden Cardiac Arrest and Sudden Cardiac Death

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