Biomedical subjects
Kathryn Buchanan Keller
Publications and source records attributed to Kathryn Buchanan Keller.
Secondary prevention of coronary artery disease in elderly persons: a treatise on a report by the American Heart Association.
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Estrogen plus progestin, benefits and risks: the "Women's Health Initiative" trials.
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Statin therapy in congestive heart failure.
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Prinzmetal's angina.
Prinzmetal's angina, often referred to as "variant" angina, is a temporary increase in coronary vascular tone (vasospasm) causing a marked, but transient reduction in luminal diameter. This coronary vasospastic state is usually focal at a single site and can occur in either a normal or diseased vessel. Patients are predominantly younger women who may not have the classical cardiovascular risk factors (except for cigarette use). PVA has been associated with vasospastic disorders such as Raynaud's phenomenon and migraine headaches. Arrhythmias are common and may be life threatening especially when the effects of vasospasm are seen in those ECG leads that reflect the potential variations of the epicardial surface of the left ventricle. Endothelial dysfunction has been considered as primarily responsible for PVA. The diagnosis is made by observing transient ST-segment elevation during the attack of angina. Since PVA is not a "demand"- induced symptom, but rather a supply (vasospastic) abnormality, exercise treadmill stress testing is of no value in the diagnosis of PVA. The most sensitive and specific test for PVA is the administration of ergonovine intravenously. Fifty micrograms at 5-minute intervals is given until a positive result or a maximum dose of 400 microg has been administered. When positive, the symptoms and associated ST-segment elevation should be present. Nitroglycerin rapidly reverses the effects of ergonovine if refractory spasm occurs. Medical therapy classically employs vasodilator drugs, which include nitrates and calcium channel blockers. The prognosis is good when there is no significant coronary artery stenosis. Treatment of associated coronary atherosclerosis in elderly patients with PVA is advised. When PVA is associated with coronary atherosclerosis, the prognosis is determined by the severity of the underlying disease. beta-Blockers and large doses of aspirin are contraindicated in PVA.
Obesity and the metabolic syndrome.
The prevalence of marked obesity is increasing rapidly among adults and has more than doubled in 10 years. Sixty-one percent of the adult population of the United States is overweight or obese. Americans are the fattest people on earth. Paradoxically these increases in the numbers of persons who are obese or overweight have occurred during recent years when Americans have been preoccupied with numerous dietary programs, diet products, weight control, health clubs, home exercise equipment, and physical fitness videos, each "guaranteed" to bring rapid results. Overweight and obesity are also world problems. The World Health Organization estimates that 1 billion people around the world are now overweight or obese. Westernization of diets has been part of the problem. Fruits, vegetables, and whole grains are being replaced by readily accessible foods high in saturated fat, sugar, and refined carbohydrates. Since class 3 obesity (morbid or extreme obesity) is associated with the most severe health complications, the incidence of hypertension, stroke, heart disease, diabetes, and peripheral vascular disease will increase substantially in the future. Recently, obesity alone has been implicated in the development of cardiac hypertrophy and CHF. The metabolic syndrome associated with abdominal obesity, which includes insulin resistance, dyslipidemia, and elevated CRP levels, identifies subjects who have an increase in cardiovascular morbidity and mortality. Twenty to 25% of the adult population in the United States have the metabolic syndrome, and in some older groups this prevalence approaches 50%. The prevalence of overweight children in the United States has also been increasing dramatically, especially among non-Hispanic blacks and Mexican-American adolescents. Overweight children usually become overweight adults. Atherosclerosis begins in childhood. The degree of atherosclerotic changes in children and young adults can be correlated with the presence of the same risk factors seen in adults. As health providers, our direction is obvious!
The cocaine-abused heart.
Recreational use of cocaine dates back to the Incas in South America 5000 years ago. Cocaine is derived from the leaves of Erythroxylon coca, a shrub native to South America. In the late 1800s, Sigmund Freud popularized the drug in Europe. He used cocaine to treat depression, asthma, cachexia, and for overcoming morphine addiction. Also in this period cocaine rapidly gained acceptance in surgical procedures as a local anesthetic and vasoconstrictor. Cocaine reached the United States in the early 1900s, and its popularity led President Taft to declare it public enemy number one in 1910. Cocaine became popular again in the 1980s. Currently cocaine use is responsible for more ED visits then any of the other illicit drugs. Because most cocaine users are young, they are at a lower risk for coronary artery atherosclerotic disease. An estimated 25 million people between the ages of 26 and 34 years have used cocaine at least once, 20% were women and 30% men. Habitual users of cocaine are estimated to number 1.5 million. Most cocaine-induced chest pains do not progress to MI, and in fact many originate in the chest wall. The chest pains due to cocaine, however, are induced by myocardial ischemia, a result of vasospasm and not a thrombotic occlusion of a coronary artery that has a ruptured atheromatous plaque. ECG findings can be misleading in the diagnosis because the early repolarization syndrome, a normal variant, is a frequent finding in young African American men. Measurement of cardiac troponin levels is the most reliable diagnostic test. Percutaneous coronary intervention and angioplasty, rather than thrombolysis, is the treatment of choice because intense coronary vasospasm is the primary pathophysiology in cocaine-induced MI.
Retirement is no excuse for physical inactivity or isolation.
At all age levels and especially in the elderly population, a sedentary lifestyle and low fitness levels are independent risk factors for all causes of mortality, including cardiovascular mortality. Exercise improves cardiovascular outcomes by increasing vagal activity and attenuating sympathetic hyperactivity. The risk of diabetes mellitus type 2 developing is reduced by 40% in men of normal weight and 60% in overweight men when on a regular exercise program. Physical activity in the elderly sustains cerebral perfusion, maintaining cognitive function. Isolation, which is not uncommon among the elderly, fosters cognitive decline. Stimulating mental activity can protect against dementia.
Arrhythmia knowledge: a qualitative study.
OBJECTIVE: The objective is to identify and describe critical care nurses' perception of arrhythmia knowledge. In addition, this study is the first step in developing levels of arrhythmia competency. DESIGN: A qualitative research design was used. Focus group technique using a semistructured group session, with a moderator, was used to gather data. Data were analyzed by the constant comparative method. SUBJECTS: The subjects were critical care nurses who work in acute care settings where they read electrocardiographic data and make treatment decisions. PROCEDURES: Five focus groups were conducted over a period of 12 months. Group size ranged from four to eight participants. Participants were asked to describe their perceptions of arrhythmia knowledge and to assign a rating score related to the level of knowledge needed to identify specific arrhythmias. RESULTS: Basic, intermediate, and advanced levels of arrhythmia knowledge were identified. This study revealed a deficit in nurses' ability to recognize and identify specific arrhythmias including heart block, aberrant conduction, and tachyarrhythmias. Understanding of lead placement concepts varied greatly among participants. CONCLUSIONS: The insight and perspective of critical care nurses related to the level of arrhythmia knowledge are needed for the development of competency measures and evidence-based teaching strategies.