Transcript Exercise Management – Angina and Silent Ischemia

Exercise Management
Angina and Silent Ischemia
Chapter 08
Exercise Management – Angina and Silent Ischemia
• Pathophysiology
• Ischemia may be
symptomatic or
silent
• Symptomatic
ischemia may be
present in several
ways. The most
common is angina.
• Symptomatic angina
is divided into three
forms: stable,
unstable, and variant
(also called
vasospastic or
Prinzmetal's angina).
Coronary Ischemia
Exercise Management – Angina and Silent Ischemia
• Stable Angina
• is reproducibly associated with a specific
amount of physical exertion, emotional stress, or
exposure to cold
• is predictably relieved promptly with rest or
sublingual nitroglycerin.
• is associated with an ischemic event due to a
coronary artery stenosis
Exercise Management – Angina and Silent Ischemia
• Unstable angina (UA)
• occurs unpredictably. It indicates intermittent complete
blockage of an artery which may soon become
permanent.
• The three principal presentations of UA are:
• angina that occurs at rest or upon awakening from sleep,
lasting more than 20 min;
• new onset, or first experience, of anginal chest pain; and
• increasing severity, frequency, duration, or threshold
pattern (level of activity that reproduces the pain) of
previously diagnosed angina.
Exercise Management – Angina and Silent Ischemia
• The pathogenesis of UA is multi-factorial and
includes one or more of the following:
• platelet aggregation or thrombosis (clot) at a site of
coronary artery narrowing;
• rupture and hemorrhage into an atherosclerotic plaque;
and
• transient periods of vasospasm at the atherosclerotic
plaque.
** Often, UA is a precursor to MI . People with this form
of angina must be admitted to a coronary care unit and
treated immediately with anti-clotting (anticoagulant)
drugs or emergency balloon angioplasty.
Exercise Management – Angina and Silent Ischemia
• Variant, vasospastic, or Prinzmetal's angina
• Occurs when the coronary arteries spasm, or
contract suddenly.
• Angiograms in this type of angina show no
obstruction or stenoses, and very little evidence
of atheroma.
• Intense vasospasm (i.e., a form of cramp of the
vessel wall muscles) alone reduces coronary
oxygen supply and results in angina. This leads
to transient narrowing.
• Treatments with medications that decrease
spasm, such as calcium-channel antagonists, are
often effective.
Exercise Management – Angina and Silent Ischemia
• Effects on the Exercise Response
• People with exercise-related myocardial
ischemia may need to stop a single session of
physical activity prematurely.
• This may result from abnormal hemodynamic
responses.
• a reduction occurs in the production of nitric oxide
(inhibiting dilation), of the coronary artery and
promoting vasoconstriction.
• Also, with diseased arteries, increased platelet
aggregation causes release of thromboxane A2, a
chemical that strongly constricts blood vessels.
Exercise Management – Angina and Silent Ischemia
• Effects on the Exercise Response
• Since the myocardial cells are not well perfused with
oxygen, they can not contract well.
• This reduces stroke volume and left ventricular
ejection fraction.
• The reduction in stroke volume limits cardiac output
and promotes fatigue.
• The decreased stroke volume may lead to
compensatory increases in heart rate, known as
increased chronotropic response, thus, a longer
warm-up is needed during exercise.
Exercise Management – Angina and Silent Ischemia
• Effects of Exercise Training
• The overall goal for people with angina is to raise the
ischemic threshold, or the point during physical stress at
which angina symptoms occur
• With exercise training, a decrease in the severity and
extent of exercise-related myocardial ischemia occurs via
a reduction in myocardial oxygen demand. (RPP used to
indirectly measure MVO2 )
• Myocardial oxygen demand is reduced by
• 1) increasing vagal tone, which
• 2) decreases heart rate, which
• 3) increases ventricular filling time.
• 4) the increased filling time produces increased end diastolic
volume, and an increased stroke volume
• Exercise training improves nitric oxide production
Exercise Management – Angina and Silent Ischemia
• Effects of Exercise Training
• There is a reduction the exercise systolic blood
pressure because of an improved myocardial
supply (vasodilatation)
• This allows for a reduced double product at a
given exercise workload, thus the symptomatic
ischemic threshold is raised
• Therefore the patient will be able to perform a
more intense physical activity before exceeding
the double product that elicits angina.
Exercise Management – Angina and Silent Ischemia
• Effects of Exercise Training
• Exercise training increases the supply of blood
and oxygen to the heart at rest and during
exercise.
• With long-term exercise training (e.g., 4-7 times/wk
for > 12 wk), there is repeated laminar shear stress on
the surface of the coronary endothelial cells of the
arterioles. This stress changes the shape of the
endothelial cells in the direction of the blood flow,
and stimulates the production of nitric oxide,
promoting vasodilation.
Exercise Management – Angina and Silent Ischemia
• Effects of Exercise Training
• With repeated exercise training, there is an
improvement in calcium handling of the smooth
muscle cells. This leads to a decrease in coronary tone
(vasoconstriction) and an increase in the
vasodilatation (relaxation) of the coronary arteries.
Exercise Management – Angina and Silent Ischemia
• Management and Medications
• The primary goals for treatment of myocardial
ischemia are to increase myocardial supply and
decrease myocardial demand. Primary
management used to decrease myocardial
oxygen demand includes medications and
exercise.
Exercise Management – Angina and Silent Ischemia
• Recommendations for Exercise Testing
• See pg. 69 text, next slide, for summary chart
• Evaluation of people suspected of having CAD
that may cause ischemia is primarily done with
graded exercise testing and may not be safe for
all people with ischemia.
• Exercise testing is contraindicated in people
with acute ischemia and UA. May be performed
in persons with non-diagnostic ECGs, negative
cardiac biomarkers, and no resting angina
within the past six hours. Angina must be
evaluated and rated during testing.
Exercise Management – Angina and Silent Ischemia
“Current evidence-based guidelines for the evaluation and treatment of UA/non-ST-segment
elevation MI (NSTEMI) state that exercise testing is contraindicated in patients with
acute ischemia but can be performed in patients with nondiagnostic electrocardiograms
(ECGs), negative cardiac biomarkers, and no resting angina within the past 6 h. In addition to
standard clinical measures obtained during exercise testing (HR, ECG, BP, signs and
symptoms, etc.) anginal symptoms, rating of anginal pain, and the exact onset and duration of
angina (if they occur) should be documented when testing patients with a history of angina.”
Exercise Management – Angina and Silent Ischemia
• Recommendations for Exercise Testing
• 12 lead ECG warranted
• During the test, documentation of anginal symptoms,
the rating of angina, and the exact onset and duration of
angina should be carefully documented.
• Indications to terminate exercise testing :
• Absolute Indications and Relative Indications for Terminating
• Absolute Indications • Drop in SBP >10 mmHg from baseline despite an increase
in work rate, accompanied by other evidence of ischemia • Moderately severe angina
(defined as 3 on standard 1-4 angina scale) • ST elevation (+1.0 mm) in leads without
diagnostic Q-waves (other than V1 or aVR)
• Relative Indications • Drop in SBP >10 mmHg from baseline despite an
increase in work rate, in the absence of other evidence of ischemia • ST or
QRS changes such as excessive ST depression (>2 mm horizontal or
downsloping ST-segment depression) or marked axis shift
Exercise Management – Angina and Silent Ischemia
• Recommendations for Exercise Testing
• Specificity in diagnosing CAD can be further
obtained by combining cardiac imaging with the
test.
• Myocardial perfusion imaging
• Echocardiography to detect wall motion
• In persons unable to exercise adequately enough
to perform the exercise test, pharmacological
stress testing can be used in conjunction with
nuclear perfusion imaging of the heart.
Exercise Management – Angina and Silent Ischemia
• Recommendations for Exercise Testing
• Pharmacological Stress Testing
• Intravenous Coronary Vasodilators - ( ex.
Persantine) These agents dilate normal coronary
arteries more than diseased ones. Blood flow to
the heart is assessed at rest and during infusion,
along with simultaneous nuclear imaging with
thallium or technetium.
• Positive Chronotropic (heart rate) and Inotropic
(contractility) Agents, also known as sympathomimetics .
Exercise Management – Angina and Silent Ischemia
Exercise Programming (chart at end of slides)
• Prior to exercise training, people with
angina must be able to:
• define angina;
• define possible anginal symptoms;
• identify their own anginal symptoms;
• describe the immediate treatment (this includes
understanding the necessity and protocol for taking
nitroglycerin in the event of an anginal attack); and
• understand the appropriate upper limits of exercise
(including heart rate, ratings of perceived exertion, and angina scales).
Exercise Management – Angina and Silent Ischemia
• Exercise Programming
• A prolonged warm-up and cool-down (> 10
min), has been shown to have an anti-anginal
effect.
• Any changes in the angina frequency, type, or
severity should be reported to the patient’s
physician.
• The upper exercise intensity limit should be set
at least 10 to 15 contractions/min below the RPP
(double product) at the original ischemic threshold
measured during the exercise test.
Exercise Management – Angina and Silent Ischemia
Exercise Programming
• In addition to the ischemic threshold, the
upper limit may be based on ventricular
dysrhythmia threshold or inadequate blood
pressure response threshold.
• The duration of the exercise session should use
ischemic preconditioning (intervals), exercise
periods of short duration (e.g., 5-10
min/session) separated by short rest periods, 2
to 3 sessions/day.
• Frequency of exercise sessions may start out
high and decrease as longer duration sessions
begin
Exercise Management – Angina and Silent Ischemia
Exercise Management – Angina and Silent Ischemia
End of Presentation