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18
Chapter 2
•
Cardiovascular Care
Release of Cardiac Enzymes and Proteins
Onset of
chest pain
6 hrs
12 hrs
18 hrs
24 hrs
30 hrs
36 hrs
42 hrs
48 hrs
3 days
4 days
5 days
6 days
7 days
8 days
9 days
10 days
11 days
12 days
Enzyme
50
20
15
10
5
4
3
2
increase
above normal
Normal range
Myoglobin
CK-MB
KEY:
Troponin I
Troponin T
CARDIAC TESTS
Electrocardiography
The electrocardiogram (ECG) is a graphical
representation (time versus amplitude of electrical
vector projection) of the electrical activity of the
heart. While imperfect as a diagnostic or prognostic
tool, it provides a significant amount of information
and is a first-line test necessary for the proper care of
the patient with potential cardiovascular disease. The
standard 12-lead ECG is of great value in identifying
myocardial ischemia, MI, rhythm and conduction
disturbances, chamber enlargement, electrolyte
imbalances, and drug toxicity.
ECG
strip
Supplemental right
precordial leads
V
3R
V
1R
V
2R
V
4R
V
5R
RA
Mid-clavicle
Anterior axillary line
Horizontal
plane of V
4
–V
6
LA
V
1
V
2
V
3
V
4
V
5
RL
LL
ECG machine
Reprinted with permission from Hinkle JL, Cheever KH.
Brunner &
Suddarth’s Textbook of Medical-Surgical Nursing
. 13th ed. Philadelphia:
Wolters Kluwer; 2013.
Exercise Stress Testing
A stress test, sometimes called a
treadmill test or exercise test, is done
while the patient walks or runs on a
motorized treadmill. The test is based
on the principle that exercise increases
myocardial demand and coronary
artery blood supply which may be
inadequate during exercise and
stress which can result in myocardial
ischemia. Exercise stress testing is a
nonevasive procedure that assesses
the heart’s response to an increased
workload. The test can demonstrate
if the blood supply is reduced in the
arteries that supply the heart during
exercise and identify appropriate
exercise levels for the patient.
EKG electrode placement
with standard left and
right precordial leads.