Cardiac/Vascular Nurse Exam Secrets Study Guide (5 page)

Metabolic syndrome is defined as a group of risk factors that put individuals at risk for developing cardiovascular disease or other comorbid conditions such as diabetes. The risk of developing metabolic syndrome is closely linked to obesity, lack of physical activity, genetic factors, and poor diet.

Metabolic syndrome is also known as syndrome X, insulin resistance syndrome, dysmetabolic syndrome, hypertriglyceridemic waist and obesity syndrome.

The 5 risk factors associated with metabolic syndrome include a large waistline, higher than normal triglyceride levels, lower than normal high-density lipoprotein cholesterol, hypertension, and hyperglycemia. An increased number of risk factors raise an individual’s risk of developing complications such as cardiovascular disease, diabetes, and/or stroke.

Approximately 47 million individuals have been diagnosed with metabolic syndrome in the United States. The incidence continues to increase annually, which can be attributed to increasing obesity rates within the United States.

The prevalence of metabolic syndrome in individuals greater than 20 years of age is more than 20%, increasing to over 40% in individuals greater than 60 years of age. Gender and ethnic descent affect the prevalence of metabolic syndrome. Mexican Americans have the highest rate of metabolic syndrome in the United States, followed by Caucasian Americans and African Americans.

The NCEP/ATP III (National Cholesterol Education Program/Adult Treatment Panel) defines metabolic syndrome as an individual with 3 or more of the following risk factors including waist circumference equal to or greater than 102 cm in men and 88 cm in women, triglyceride levels greater than 150 mg/dL, high-density lipid cholesterol less than 40 mg/dL in men and less than 50 mg/dL in women, blood pressure greater than or equal to 130/85 mmHg and fasting plasma glucose greater than 100 mg/dL.

The World Health Organization (WHO) defines metabolic syndrome as an individual with diabetes, impaired glucose tolerance (IGT), impaired fasting glucose (IFG) or insulin resistance, plus 2 or more of the following risk factors including body mass index greater than 30 kg/m
²
and/or waist-to-hip ratio greater than 0.9 in men and greater than 0.85 in women, triglyceride levels greater than 150 mg/dL and/or high-density lipid cholesterol less than 35 mg/dL in men and less than 39 mg/dL in women, blood pressure greater than or equal to 140/90 mmHG and urinary albumin excretion greater than equal to 20 mg/min or urinary albumin: creatinine ratio greater than or equal to 30 mg/g.

Causes and risk factors

The exact mechanisms that induce metabolic syndrome in some individuals remain unclear. The pathophysiology is very complex and poorly understood. However, several risk factors put some individuals at an increased risk of developing the condition. Risk factors associated with metabolic syndrome include obesity, lack of physical activity, dyslipidemia, history of familial diabetes, polycystic ovarian syndrome, insulin resistance, stress, aging, genetic factors and hormonal changes.

While genetic factors and aging cannot be addressed, individuals can prevent obesity by maintaining proper weight with diet and exercise as well as managing other comorbid conditions.

Patients diagnosed with metabolic syndrome also typically form blood clots and present with constant low-grade inflammation throughout the body. Additional conditions that have been associated with metabolic syndrome include fatty liver, polycystic ovary syndrome, gallstones, and sleep apnea.

Symptoms

The symptoms of metabolic syndrome present as a combination of other conditions. Therefore, the symptoms of metabolic syndrome are based on underlying conditions that define the condition such as hypertension, diabetes, or high cholesterol.

Other comorbid conditions associated with metabolic syndrome include elevated uric acid levels, fatty liver disease, polycystic ovary syndrome, hemochromatosis, and acanthosis nigricans.

Screening and diagnosis

Physical examination and diagnostic tools are used to diagnose metabolic syndrome. Patients with 3 or more of the following risk factors including abdominal obesity, higher than normal triglyceride levels, higher than normal high-density lipid cholesterol levels, hypertension, and hyperglycemia are diagnosed with metabolic syndrome. Patients with 1 or more than the above symptoms should seek medical attention to prevent other complications or comorbid conditions.

Patients with type II diabetes should be screened for metabolic syndrome as more than 80% of type II diabetes patients have comorbid metabolic syndrome and are at a higher risk for cardiovascular disease.

Endothelial dysfunction

Endothelial dysfunction is defined as abnormal functioning of the cells forming the endothelium, the innermost lining of blood vessels. It is characterized by reduced vasodilation, increased proinflammatory response and prothrombotic properties.

Patients with endothelial dysfunction typically present with an inability of arteries and veins to dilate properly or fully. Biochemical dysfunction of the endothelium leads to problems with coagulation, platelet adhesion, immune function and electrolyte balance.

Individuals diagnosed with endothelial dysfunction are at a higher risk for developing cardiovascular disease as well as having a heart attack or stroke due to presence of atherosclerosis. They are also at risk for developing the following comorbid complications, if not already present, including congestive heart failure, chronic renal failure, peripheral artery disease, and diabetes. The prognosis of endothelial dysfunction is dependent on the degree and extent of the disease as well as presence of other comorbid conditions.

Physical examination and comorbid conditions suggest the condition and diagnostic tools can be used to diagnose endothelial dysfunction. Patients with elevated risk for the disease including those with diabetes and other cardiovascular risk factors should be screened for the condition.

Diagnostic screening for endothelial dysfunction can be determined using the following methods: iontophoresis of acetylcholine, intraarterial administration of vasoactive agents, localized heating of the skin and temporary arterial occlusion via inflating a blood pressure cuff to high pressures. Another more invasive approach is intracoronary catheterization, but it is not often performed due to increased risk of complications.

Hypertension

Hypertension is defined as high blood pressure chronically elevated at greater than or equal to 140/90 mmHg. Hypertension can be classified as primary hypertension or as result of a comorbid condition and referred to as secondary hypertension. Secondary hypertension can be attributed to kidney disease, metabolic disorders, or cancer. Primary hypertension occurs in 90% to 95% of individuals diagnosed with high blood pressure, as compared to secondary hypertension, which occurs in 2% to 10%.

The incidence and prevalence of hypertension increase with natural aging. In the United States, more than 40 million individuals have been estimated to have hypertension. In the United States, the prevalence of hypertension tends to be higher in Blacks and Hispanics as compared to Caucasians. Women under the age of 50 tend to have a lower risk of hypertension than men. However, women over the age of 50 have higher risk of hypertension than men.

Causes and risk factors

Primary hypertension can be attributed to a variety of causes including emotional stress, licorice toxicity, salt sensitivity, high renin levels, insulin resistance, sleep apnea, genetic factors, natural aging, and other factors. Individuals with a family member with primary hypertension are at an increased risk of developing the condition. Also, being of African American descent increases risk of hypertension compared to Caucasians.

Secondary hypertension can be attributed to renal disease, adrenal disease, Cushing syndrome, spinal misalignment, adrenal gland tumor, alcohol poisoning, anxiety, stress, pain, arteriosclerosis, obesity, pregnancy, hyperthyroidism, hypothyroidism, retroperitoneal fibrosis, oral contraceptives, antihypertensive medication withdrawal, and drugs such as NSAIDs.

The 2003 National Heart, Lung, and Blood Institute (NHLBI) guidelines divide blood pressure into 4 general categories for adults that include:

• The first category is “normal blood pressure,” which includes individuals with a blood pressure below 120/80 mmHg.
  
• The secondary category is called “prehypertension” and includes individuals with a systolic blood pressure ranging from 120 to 139 and diastolic blood pressure ranging from 80 to 89. Without lifestyle modifications, prehypertension may worsen over time and should be monitored by a practicing clinician.
  
• The third category is referred to as “stage 1 hypertension” and includes individuals with systolic pressure ranging from 140 to 159 and/or a diastolic pressure ranging from 90 to 99.
  
• The fourth category is “stage 2 hypertension,” which includes individuals with severe hypertension. Individuals who present with a systolic pressure above 160 and/or diastolic pressure above 100.
  

Diagnosis, screening and symptoms

Hypertension is typically diagnosed during routine physical examinations or when addressing other conditions or concerns. The only test used for diagnosis of hypertension is blood pressure measurement. However, blood pressure measurements need to be taken on a regular basis when persistent high blood pressure is a concern. Also, proper measurement is necessary for accurate diagnosis. If other cardiovascular complications are suspected, other testing including echocardiogram, urinalysis, CBC, serum electrolytes, serum creatine, serum glucose, and x-rays may be performed.

Most patients present with no symptoms, but some patients experience headaches, fatigue, dizziness, confusion, chest pain, irregular heartbeat, nosebleed, blurred vision, facial flushing, or tinnitus. Hypertension is sometimes misdiagnosed as stress and/or anxiety. Although stress and anxiety can contribute to elevated blood pressure, they cannot cause persistent hypertension.

Dyslipidemia

Dyslipidemia is a disorder of lipoprotein metabolism, including hyperlipidemia and hypolipidemia. Dyslipidemia can be classified as primary dyslipidemia or as result of a comorbid condition and referred to as secondary dyslipidemia. The condition is typically characterized by elevations in total cholesterol, low-density lipoprotein cholesterol, triglyceride levels, and a decrease in high-density cholesterol levels.

Primary dyslipidemia is more prevalent among adolescents and children than in adults. Secondary dyslipidemia is the main cause dyslipidemia in adults. African Americans and Hispanic Americans are at greater risk for the development of dyslipidemia and cardiovascular complications as compared to Caucasian Americans.

Causes and risk factors

The causes of dyslipidemia include genetic as well as environmental contributions.

In secondary dyslipidemia, increases in low-density lipoprotein levels can be caused by diabetes, hypothyroidism, nephrotic syndrome, obstructive liver disease, anabolic steroids, progestins, beta-adrenergic blockers, and thiazides. Increases in triglyceride levels can be caused by diabetes, hypothyroidism, obesity, renal insufficiency, beta-adrenergic blockers, bile acid binding resins, estrogens, and ticlopidine. Decreases in high-density lipoprotein levels can be caused by cigarette smoking, diabetes, hypertriglyceridemia, menopause, obesity, puberty, uremia, anabolic steroids, beta-adrenergic blockers, and progestins.

The risk factors associated with dyslipidemia that can lead to coronary heart disease include natural aging, male gender, family history of cardiovascular disease, cigarette smoking or tobacco use, hypertension and diabetes.

Diagnosis, screening and symptoms

The goal of dyslipidemia treatment is to control lipid levels, decreasing low-density lipoprotein levels and triglyceride levels and increasing high-density lipoprotein levels, as well as prevent the onset of cardiovascular diseases such as coronary artery disease, peripheral artery disease, heart attack and stroke. Treatment algorithms involve lifestyle modifications and pharmacologic management.

Individuals prescribed lifestyle modifications and pharmacologic drugs should be monitored by a clinical practitioner on a regular basis. Also, lipid levels should be checked on a periodic basis after starting treatment in case the dose needs to be titrated.

Myocardial infarction

Myocardial infarction is defined as the lack of blood flow to the heart caused by plaque rupture or blockage. Myocardial infarction is also known as heart attack or acute myocardial infarction.

In the United States, myocardial infarction and other cardiac ischemic conditions are the leading cause of mortality. Coronary heart disease is responsible for 1 in 5 deaths in the United States. Currently, the prevalence of coronary artery disease is over 7 million in men and over 6 million in women. More than 1 million individuals suffer an acute myocardial infarction per year, with nearly 40% dying because of the incident. Men are at a higher risk of myocardial infarction than women, especially with increasing age.

Causes and risk factors

Risk factors that can lead to myocardial infarction include a family history of vascular disease such as atherosclerosis, coronary artery disease and/or angina, previous heart attack or stroke, previous episodes of syncope or arrhythmias, natural aging, smoking or tobacco use, lack of physical activity, excessive alcohol consumption, abuse of drugs, elevated triglyceride levels, elevated low-density lipoprotein levels, decreased high-density lipoprotein levels, diabetes, hypertension, acute infections, obesity, chronic renal failure, stress, and anxiety.