Ischaemic Heart Disease
STUDY GUIDE
I. Myocardial ischemia is characterized by a
metabolic Oxygen demand that exceeds the
oxygen supply.
II. Ischemia can therefore result from a marked
Increase in myocardial metabolic demand, a
reduction In myocardial oxygen delivery, or a
combination Of both.
III. Common causes include coronary Arterial
vasospasm or thrombosis; severe hypertension
Or tachycardia (particularly in the presence Of
ventricular hypertrophy); severe hypotension,
Hypoxemia, or anemia; and severe aortic
stenosis or Regurgitation.
IV. The most common cause of myocardial
ischemia is atherosclerosis of the coronary
arteries.
V. CAD is responsible for about 25% of all deaths in
Western societies and is a major cause of
perioperative morbidity and mortality.
VI. The overall incidence of CAD in surgical
patients is estimated to be between 5% and
10%.
VII. Major risk factors for CAD include
hyperlipidemia, hypertension, diabetes,
cigarette smoking, increasing age, male sex,
and a positive family history.
VIII. Other risk factors include obesity, a history
of cerebrovascular or peripheral vascular
disease, menopause, use of high-estrogen oral
contraceptives (in women who smoke), and a
sedentary lifestyle.
IX. CAD may be clinically manifested by
, symptoms of myocardial necrosis
(infarction), ischemia (usually angina),
arrhythmias (including sudden death), or
ventricular dysfunction (congestive heart
failure).
X. When symptoms of congestive heart
failure predominate, the term
―ischemic cardiomyopathy is often
used.
Perioperative risk
I. The key to reducing perioperative CVS morbidity is to identify
high-risk patients beforehand.
II. CVS risk is influenced by patient factors (including functional capacity)
and by the nature of the planned surgery.
III. Exercise tolerance is a major predictor of perioperative risk.
IV. The physiological response to major surgery increases the O2
demand by up to 40%, requiring a subsequent increase in O2
delivery.
V. The ability to exercise is an excellent indicator of CVS fitness‘.
VI. It is usually expressed in metabolic equivalents of task (METs) on a scale
defined by the Duke Activity Status Index
VII. One MET is the resting O2 consumption of a 40-year-old 70kg ♂ (3.5mL/kg/min).
VIII. Patients who cannot sustain 4 METs of physical activity
frequently have adverse outcomes following high-risk surgery.
• Unstable angina is defined as
• an abrupt increase in severity, frequency (more than
three episodes per day), or duration of anginal attacks (crescendo angina)
I. angina at rest; or
II. new onset of angina (within the past 2 months) with
severe or frequent episodes (more than three per day).
, Unstable angina may occur following MI or be precipitated by
noncardiac medical conditions (including severe anemia, fever, infections,
thyrotoxicosis, hypoxemia, and emotional distress) in previously stable
patients.
Unstable angina, particularly when it is associated with significant STsegment
changes at rest, usually reflects severe underlying coronary disease and
frequently precedes MI.
Plaque disruption with platelet aggregates or thrombi and vasospasm are
frequent pathological correlates.
Critical stenosis in one or more major coronary arteries is present in
more than 80% of patients with these symptoms.
Patients with unstable angina require evaluation and treatment,
which may include admission to a coronary care unit and some form of
coronary intervention.
Chronic Stable
Angina
Anginal chest pains are most often substernal, exertional, radiating to the neck
or arm, and relieved by rest or nitroglycerin.
Variations are common, including epigastria, back, or neck pain, or
transient shortness of breath from ventricular dysfunction (angina equivalent).
Nonexertional ischemia and silent (asymptomatic) ischemia are recognized
as fairly common occurrences.
Patients with diabetes have an increased incidence of silent ischemia.
Symptoms are generally absent until the atherosclerotic lesions cause 50%
to 75% occlusion of the coronary circulation.
When a stenotic segment reaches 70% occlusion, maximum compensatory
dilatation is usually present distally: blood flow is generally adequate at rest,
but becomes inadequate with increased metabolic demand.
• An extensive collateral blood supply allows some patients to
remain relatively asymptomatic despite severe disease.
• Coronary vasospasm is also a cause of transient transmural ischemia in
some patients; 90% of vasospastic episodes occur at preexisting
stenotic lesions in epicardial vessels and are often precipitated by a
variety of factors, including emotional upset and hyperventilation
STUDY GUIDE
I. Myocardial ischemia is characterized by a
metabolic Oxygen demand that exceeds the
oxygen supply.
II. Ischemia can therefore result from a marked
Increase in myocardial metabolic demand, a
reduction In myocardial oxygen delivery, or a
combination Of both.
III. Common causes include coronary Arterial
vasospasm or thrombosis; severe hypertension
Or tachycardia (particularly in the presence Of
ventricular hypertrophy); severe hypotension,
Hypoxemia, or anemia; and severe aortic
stenosis or Regurgitation.
IV. The most common cause of myocardial
ischemia is atherosclerosis of the coronary
arteries.
V. CAD is responsible for about 25% of all deaths in
Western societies and is a major cause of
perioperative morbidity and mortality.
VI. The overall incidence of CAD in surgical
patients is estimated to be between 5% and
10%.
VII. Major risk factors for CAD include
hyperlipidemia, hypertension, diabetes,
cigarette smoking, increasing age, male sex,
and a positive family history.
VIII. Other risk factors include obesity, a history
of cerebrovascular or peripheral vascular
disease, menopause, use of high-estrogen oral
contraceptives (in women who smoke), and a
sedentary lifestyle.
IX. CAD may be clinically manifested by
, symptoms of myocardial necrosis
(infarction), ischemia (usually angina),
arrhythmias (including sudden death), or
ventricular dysfunction (congestive heart
failure).
X. When symptoms of congestive heart
failure predominate, the term
―ischemic cardiomyopathy is often
used.
Perioperative risk
I. The key to reducing perioperative CVS morbidity is to identify
high-risk patients beforehand.
II. CVS risk is influenced by patient factors (including functional capacity)
and by the nature of the planned surgery.
III. Exercise tolerance is a major predictor of perioperative risk.
IV. The physiological response to major surgery increases the O2
demand by up to 40%, requiring a subsequent increase in O2
delivery.
V. The ability to exercise is an excellent indicator of CVS fitness‘.
VI. It is usually expressed in metabolic equivalents of task (METs) on a scale
defined by the Duke Activity Status Index
VII. One MET is the resting O2 consumption of a 40-year-old 70kg ♂ (3.5mL/kg/min).
VIII. Patients who cannot sustain 4 METs of physical activity
frequently have adverse outcomes following high-risk surgery.
• Unstable angina is defined as
• an abrupt increase in severity, frequency (more than
three episodes per day), or duration of anginal attacks (crescendo angina)
I. angina at rest; or
II. new onset of angina (within the past 2 months) with
severe or frequent episodes (more than three per day).
, Unstable angina may occur following MI or be precipitated by
noncardiac medical conditions (including severe anemia, fever, infections,
thyrotoxicosis, hypoxemia, and emotional distress) in previously stable
patients.
Unstable angina, particularly when it is associated with significant STsegment
changes at rest, usually reflects severe underlying coronary disease and
frequently precedes MI.
Plaque disruption with platelet aggregates or thrombi and vasospasm are
frequent pathological correlates.
Critical stenosis in one or more major coronary arteries is present in
more than 80% of patients with these symptoms.
Patients with unstable angina require evaluation and treatment,
which may include admission to a coronary care unit and some form of
coronary intervention.
Chronic Stable
Angina
Anginal chest pains are most often substernal, exertional, radiating to the neck
or arm, and relieved by rest or nitroglycerin.
Variations are common, including epigastria, back, or neck pain, or
transient shortness of breath from ventricular dysfunction (angina equivalent).
Nonexertional ischemia and silent (asymptomatic) ischemia are recognized
as fairly common occurrences.
Patients with diabetes have an increased incidence of silent ischemia.
Symptoms are generally absent until the atherosclerotic lesions cause 50%
to 75% occlusion of the coronary circulation.
When a stenotic segment reaches 70% occlusion, maximum compensatory
dilatation is usually present distally: blood flow is generally adequate at rest,
but becomes inadequate with increased metabolic demand.
• An extensive collateral blood supply allows some patients to
remain relatively asymptomatic despite severe disease.
• Coronary vasospasm is also a cause of transient transmural ischemia in
some patients; 90% of vasospastic episodes occur at preexisting
stenotic lesions in epicardial vessels and are often precipitated by a
variety of factors, including emotional upset and hyperventilation
