Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 118

A major danger with progressive CAD is that narrowed coronary arteries can easily become completely blocked by a thrombus (clot) or a dislodged piece of fatty plaque. Frequently an area of plaque will rupture, activating the clotting cascade, leading to rapid thrombosis and total vessel occlusion that is indicative of an MI (heart attack).

During infarction the cardiac muscle cells of the myocardium are deprived of oxygen and begin to die. Most MIs result in a characteristic, concentric pattern of tissue damage made up of the area of necrosis (dead tissue), the area of injury (living but damaged tissue) and the ischaemic zone (healthy living tissue but with reduced oxygen supply).

All three concentric areas surrounding the occlusion will collectively reduce the heart’s ability to function as an effective pump.

Although MI can come on suddenly and without warning, often a variety of symptoms are initially present. These can include chest pain, shortness of breath (dyspnoea), increased sweating (hyperhidrosis), feeling of impending doom (severe anxiety), confusion or lethargy (NHS, 2018); you may remember all of these were present in George’s case study at the beginning of this chapter. However, not everyone will experience MI in the same way; older women often present atypically with research indicating that less than half of women over the age of 75 experienced chest pain during MI (Milner et al., 2004).

To develop your knowledge of heart disease, read through Gloria’s case study before attempting Activity 3.3.