My Draft Book for HARRISON INTERNAL MEDICINE

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EMOTIONAL AND PSYCHIATRIC CONDITIONS
As many as 10% of patients who present to emergency departments with acute chest
pain have panic disorder or other emotional conditions. The symptoms in these
populations are highly variable, but frequently the discomfort is described as visceral
tightness or aching that lasts more than 30 min. Some patients offer other atypical
descriptions, such as pain that is fleeting, sharp, and/or localized to a small region. The
electrocardiogram in patients with emotional conditions may be difficult to interpret if
hyperventilation causes ST-T-wave abnormalities. A careful history may elicit clues of
depression, prior panic attacks, somatization, agoraphobia, or other phobias.
APPROACH TO THE PATIENT
The evaluation of the patient with chest discomfort must accommodate two goals—
determining the diagnosis and assessing the safety of the immediate management
plan. The latter issue is often dominant when the patient has acute chest
discomfort, such as patients seen in the emergency department. In such settings,
the clinician must focus first on identifying patients who require aggressive
interventions to diagnose or manage potentially life-threatening conditions,
including acute ischemic heart disease, acute aortic dissection, pulmonary
embolism, and tension pneumothorax. If such conditions are unlikely, the clinician
must address questions such as the safety of discharge to home, admission to a
non-coronary care unit facility, or immediate exercise testing. Table 12-3 displays a
sequence of questions that can be used in the evaluation of the patient with chest
discomfort, with the diagnostic entities that are most important for consideration at
each stage of the evaluation.

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ACUTE CHEST DISCOMFORT
In patients with acute chest discomfort, the clinician must first assess the patient's
respiratory and hemodynamic status. If either is compromised, initial management
should focus on stabilizing the patient before the diagnostic evaluation is pursued.
If, however, the patient does not require emergent interventions, then a focused
history, physical examination, and laboratory evaluation should be performed to
assess the patient's risk of life-threatening conditions.
The history should include questions about the quality and location of the chest
discomfort (Table 12-2). The patient should also be asked about the nature of onset
of the pain and its duration. Myocardial ischemia is usually associated with a
gradual intensification of symptoms over a period of minutes. Pain that is fleeting or
that lasts hours without being associated with electrocardiographic changes is not
likely to be ischemic in origin. Although the presence of risk factors for coronary
artery disease may heighten concern for this diagnosis, the absence of such risk
factors does not lower the risk for myocardial ischemia enough to be used to justify
a decision to discharge a patient.
Wide radiation of chest pain increases probability that pain is due to myocardial
infarction. Radiation of chest pain to the left arm is common with acute ischemic
heart disease, but radiation to the right arm is also consistent with this diagnosis.
Right shoulder pain is common with acute cholecystitis, but this syndrome is usually
accompanied by pain that is located in the abdomen rather than chest. Chest pain
that radiates between the scapulae raises the question of aortic dissection.
The physical examination should include evaluation of blood pressure in both arms
and of pulses in both legs. Poor perfusion of a limb may be due to an aortic
dissection that has compromised flow to an artery branching from the aorta. Chest
auscultation may reveal diminished breath sounds; a pleural rub; or evidence of
pneumothorax, pulmonary embolism, pneumonia, or pleurisy. Tension pneumothorax
may lead to a shift in the trachea from the midline, away from the side of the
pneumothorax. The cardiac examination should seek pericardial rubs, systolic and
diastolic murmurs, and third or fourth heart sounds. Pressure on the chest wall may
reproduce symptoms in patients with musculoskeletal causes of chest pain; it is
important that the clinician ask the patient if the chest pain syndrome is being
completely reproduced before drawing too much reassurance that more serious
underlying conditions are not present. An electrocardiogram is an essential test for adults with chest discomfort that is not
due to an obvious traumatic cause. In such patients, the presence of
electrocardiographic changes consistent with ischemia or infarction (Chap. 210) is
associated with high risks of acute myocardial infarction or unstable angina (Table
12-4); such patients should be admitted to a unit with electrocardiographic
monitoring and the capacity to respond to a cardiac arrest. The absence of such
c hanges does not exclude acute ischemic heart
disease, but the risk of life-threatening complications is low for patients with normal
electrocardiograms or only nonspecific ST-T-wave changes. If these patients are
not considered appropriate for immediate discharge, they are often candidates for
early or immediate exercise testing.
Markers of myocardial injury are often obtained in the emergency department
evaluation of acute chest discomfort. The most commonly used markers are
creatine kinase (CK), CK-MB, and the cardiac troponins (I and T). Rapid bedside
assays of the cardiac troponins have been developed and shown to be sufficiently
accurate to predict prognosis and guide management. Some data support the use of
other markers, such as serum myoglobin, C-reactive protein (CRP), and B-type
natriuretic peptide (BNP); their roles are the subject of ongoing research. Single
values of any of these markers do not have high sensitivity for acute myocardial
infarction or for prediction of complications. Hence, decisions to discharge patients
home should not be made on the basis of single negative values of these tests.
Provocative tests for coronary artery disease are not appropriate for patients with
ongoing chest pain. In such patients, rest myocardial perfusion scans can be
considered; a normal scan reduces the likelihood of coronary artery disease, and
can help avoid admission of low-risk patients to the hospital. Clinicians frequently
employ therapeutic trials with sublingual nitroglycerin or antacids or, in the stable
patient seen in the office setting, a proton pump inhibitor. A common error is to
assume that a response to any of these interventions clarifies the diagnosis. While
such information is often helpful, the patient's response may be due to the placebo
effect. Hence, myocardial ischemia should never be considered excluded solely
because of a response to antacid therapy. Similarly, failure of nitroglycerin to
relieve pain does not exclude the diagnosis of coronary disease.
If the patient's history or examination is consistent with aortic dissection, imaging
studies to evaluate the aorta must be pursued promptly because of the high risk of
catastrophic complications with this condition. A chest x-ray is not sufficient to
exclude this diagnosis. Appropriate tests include a chest computed tomography
scan with contrast or a magnetic resonance imaging scan in patients who are
hemodynamically stable, or a transesophageal echocardiogram in patients who are
less stable. Aortic angiography is no longer a first test at most institutions.
Acute pulmonary embolism should be considered in patients with respiratory
symptoms, pleuritic chest pain, hemoptysis, or a history of venous
thromboembolism or coagulation abnormalities. Initial tests usually include a lung
scan and/or pulmonary arteriography.
If patients with acute chest discomfort show no evidence of life-threatening
conditions, the clinician should then focus on serious chronic conditions with the
potential to cause major complications, the most common of which is stable angina.
Early use of exercise electrocardiography, stress echocardiography, or stress
perfusion imaging for such patients, whether in the office or the emergency
department, is now an accepted management strategy for low-risk patients.
Exercise testing is not appropriate, however, for patients who (1) report pain that is
believed to be ischemic occurring at rest or (2) have electrocardiographic changes
not known to be old that are consistent with ischemia.
Patients with sustained chest discomfort who do not have evidence for lifethreatening
conditions should be evaluated for evidence of conditions likely to
benefit from acute treatment (Table 12-3). Pericarditis may be suggested by the
history, physical examination, and electrocardiogram (Table 12-2). Clinicians should
carefully assess blood pressure patterns and consider echocardiography in such
patients to detect evidence of impending pericardial tamponade. Chest x-rays can
be used to evaluate the possibility of pulmonary disease.

[ 本帖最后由 zhangheng1020 于 2006-3-9 13:50 编辑 ]

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GUIDELINES AND CRITICAL PATHWAYS FOR ACUTE CHEST PAIN
Guidelines for the initial evaluation for patients with acute chest pain have been
developed by the American College of Cardiology, American Heart Association, and
other organizations. These guidelines recommend performance of an
electrocardiogram for virtually all patients with chest pain who do not have an
obvious noncardiac cause of their pain, and performance of a chest x-ray for
patients with signs or symptoms consistent with congestive heart failure, valvular
heart disease, pericarditial disease, or aortic dissection or aneurysm.
Other organizations, including the Agency for Health Care Policy and Research
(AHCPR) and the National Heart Attack Alert Program, have also issued guidelines
for management of patients with a high probability of acute ischemic heart disease.
In these and other guidelines, patients with possible or probable acute myocardial
infarction as suggested by the description of their pain or ECG findings are
expected to be admitted to the hospital. The AHCPR guidelines for unstable angina
note that not all patients with that syndrome require admission but recommend that
patients with unstable angina be monitored electrocardiographically during their
evaluation; that those with ongoing rest pain should be placed at bed rest during the
initial phase of stabilization.
The American Heart Association has published guidelines for the use of exercise
testing in the emergency department. These recommendations include having two
sets of cardiac enzymes or troponins at 4-h intervals that are normal; an ECG at
presentation and preexercise ECG that shows no significant change; absence of rest
ECG abnormalities that preclude accurate interpretation of an exercise ECG; and
absence of ischemic chest pain at the time of exercise testing or during the
observation period after admission to the emergency department.
Many medical centers have adopted critical pathways and other forms of guidelines
to increase efficiency and to expedite the treatment of patients with high-risk acute
ischemic heart disease syndromes. These guidelines emphasize the following
strategies:

􀁺 Rapid identification and treatment of patients for whom emergent reperfusion
therapy, either via percutaneous coronary interventions or thrombolytic
agents, is likely to lead to improved outcomes.
􀁺 Triage to non-coronary care unit monitored facilities such as intermediate
care units or chest pain units of patients with a low risk for complications,
such as patients without new ischemic changes on their electrocardiograms
and without ongoing chest pain. Such patients can usually be safely observed
in non-coronary care unit settings, undergo early exercise testing, or be
discharged home. Risk stratification can be assisted through use of 􀁺 Rapid identification and treatment of patients for whom emergent reperfusion
therapy, either via percutaneous coronary interventions or thrombolytic
agents, is likely to lead to improved outcomes.
􀁺 Triage to non-coronary care unit monitored facilities such as intermediate
care units or chest pain units of patients with a low risk for complications,
such as patients without new ischemic changes on their electrocardiograms
and without ongoing chest pain. Such patients can usually be safely observed
in non-coronary care unit settings, undergo early exercise testing, or be
discharged home. Risk stratification can be assisted through use of 􀁺 Rapid identification and treatment of patients for whom emergent reperfusion
therapy, either via percutaneous coronary interventions or thrombolytic
agents, is likely to lead to improved outcomes.
􀁺 Triage to non-coronary care unit monitored facilities such as intermediate
care units or chest pain units of patients with a low risk for complications,
such as patients without new ischemic changes on their electrocardiograms
and without ongoing chest pain. Such patients can usually be safely observed
in non-coronary care unit settings, undergo early exercise testing, or be
discharged home. Risk stratification can be assisted through use of prospectively validated multivariate algorithms that have been published for
acute ischemic heart disease and its complications.
􀁺 Shortening lengths of stay in the coronary care unit and hospital.
Recommendations regarding the minimum length of stay in a monitored bed
for a patient who has no further symptoms have decreased in recent years to
12 h or less if exercise testing or other risk stratification technologies are
available.

[ 本帖最后由 zhangheng1020 于 2006-3-9 13:52 编辑 ]

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draft 1

[ 本帖最后由 zhangheng1020 于 2006-3-9 14:12 编辑 ]

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draft 1

[ 本帖最后由 zhangheng1020 于 2006-3-9 19:06 编辑 ]

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draft 1

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DRAFT 1 (FINISHED LAST NIGHT)

[ 本帖最后由 zhangheng1020 于 2006-3-10 07:12 编辑 ]

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chapter 12 draft 2

[ 本帖最后由 zhangheng1020 于 2006-3-13 23:49 编辑 ]

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[ 本帖最后由 zhangheng1020 于 2006-3-13 23:51 编辑 ]

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快要看死了~~~
坚持，努力，然后做完以后就可以号啕大哭了 = =