Chapter 16 Clinical Exemplar

CLINICAL EXEMPLARS

Multiple conditions contribute to impaired perfusion—far more than are described in this text. Box 16.2 lists common conditions associated with impaired perfusion across the lifespan; further details about these conditions can be found in pathophysiology, medical–surgical, and pediatric nursing textbooks.

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Atrial Fibrillation

This cardiac dysrhythmia is characterized by disorganized electrical activity from impulses that trigger atrial contraction that are not initiated from the sinoatrial (SA) node. The result is ineffective atrial contraction, with atrial rates as high as 350 to 600 beats/min. Because the ventricles do not have time to fill, cardiac output is reduced. The pulse rhythm is irregularly irregular. Atrial fibrillation may occur in brief episodes or may be permanent. It is the most common, clinically significant dysrhythmia with respect to morbidity and mortality rates.10 Approximately 2% of people younger than age 65 years and approximately 9% of people older than age 65 years have atrial fibrillation. Clots may form in the atria from blood stasis, which can become emboli that flow to the brain causing strokes. Atrial fibrillation accounts for as many as 20% of all ischemic strokes.20

BOX 16.2  EXEMPLARS OF IMPAIRED PERFUSION

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Central Perfusion

Cardiac Dysrhythmias

• Asystole

• Atrial fibrillation

• Third-degree heart block

• Ventricular fibrillation

Valvular Heart Disease

• Aortic stenosis or insufficiency

• Mitral valve stenosis or insufficiency

Congenital Defects

• Atrial septal defect

• Coarctation of the aorta

• Tetralogy of Fallot

• Ventricular septal defect

Shock

• Anaphylactic shock

• Cardiogenic shock

• Hypovolemic shock

• Neurogenic shock

• Septic shock

Other Conditions Associated With Central Perfusion

• Cardiomyopathy

• Cor pulmonale

• Endocarditis

• Heart failure

• Pulmonary hypertension

• Ruptured arterial aneurysm (leading to hemorrhagic shock)

Local/Tissue Perfusion

• Acute myocardial infarction

• Arterial embolism

• Atherosclerosis

• Hyperlipidemia

• Hypertension

• Peripheral artery disease

• Pulmonary embolism

• Raynaud disease

• Sickle cell disease

• Stroke

• Venous thromboembolism

Acute Myocardial Infarction

When perfusion from the coronary arteries is impaired, sustained ischemia causes irreversible myocardial cell death (necrosis) resulting in acute myocardial infarction. Acute myocardial infarction – often referred to as AMI – is one part of acute coronary syndrome, which also includes unstable angina caused by temporary ischemia to the myocardium and specific types of acute myocardial infarction. Most acute myocardial infarctions are caused by a thrombus or occlusion that impairs blood flow. Risk factors include medical conditions (such as coronary artery disease, hypertension, hyperlipidemia, and diabetes) and lifestyle choices (such as smoking, excessive alcohol use, physical inactivity, unhealthy diet, and excessive alcohol use). Chest pain; pain or discomfort in one or both arms, the jaw, back, or stomach; shortness of breath; lightheadedness; and nausea are common symptoms.

Heart Failure

Heart failure develops when either ventricle fails to pump efficiently. This condition can develop in response to a weak myocardium that is unable to adequately pump blood or excessive afterload that increases the work of the heart. This causes pressure to back up through the chambers of the heart and ultimately reduces perfusion and causes fluid overload. Heart failure is associated with hypertension, coronary artery disease, diabetes, and obesity. Heart failure can be categorized into left- and right-sided heart failure. In left-sided failure, the most common type, the impairment, causes blood to back up into the left atrium and pulmonary veins, producing dyspnea; coughing up pink, foamy mucus; and irregular heartbeat (S3 heart sound). In right-sided failure, the blood backs up into the right atrium and venous circulation, producing edema of legs, feet, and ankles, and weight gain from fluid retention. Many individuals who start with left-sided heart failure develop right-sided heart failure without proper treatment.

Hyperlipidemia

Elevated blood levels of cholesterol and triglycerides indicate hyperlipidemia. Diets high in cholesterol and genetic inheritance are common causes of hypercholesterolemia. Triglycerides are a simple fat compound obtained from animal and vegetable fats. High cholesterol has no symptoms, but it thickens arterial walls in coronary or cerebral vessels, leading to myocardial infarction or stroke.

Hypertension

Hypertension occurs when there is excessive pressure or force of blood flowing through arteries. Nearly half of American adults have hypertension, and the risk increases with age. Criteria for normal blood pressure is a systolic pressure less than 120 mm Hg and a diastolic pressure less than 80 mm Hg. Four classifications of hypertension are presented in Table 16.2

Elevated blood pressure increases the workload of the heart and damages endothelium contributing to atherosclerosis. Because hypertension usually has no symptoms, people should routinely have their blood pressures measured. Nearly half of American adults have hypertension, and the risk increases with age.26

Peripheral Artery Disease

The gradual thickening of arterial walls reduces perfusion in upper and lower extremities, resulting in peripheral artery disease. Risk factors include tobacco use, hyperlipidemia, uncontrolled hypertension, and diabetes mellitus. The risk for peripheral artery disease increases with age and typically appears in the sixth to eighth decades. Manifestations include decreased to absent peripheral pulses; cool skin temperature; loss of hair and thin, taut, shiny skin on affected extremities; and ischemic pain during exercise (intermittent claudication).14