Epinephrine is the neurotransmitter of the sympathetic nervous system. - causing systemic vasoconstriction, binds to the cardiac beta-receptors, resulting in increased heart rate and increased cardiac output.
CMC Cardiac Medicine Certification
Acute Coronary Syndrome (ACS): any group of clinical symptoms resulting from acute
myocardial ischemia. - begins with the rupture of atherosclerotic plaque, creating an
injured area on the endothelium.
platelet activation of the coagulation cascade and the formation of a thrombus over the
injured area ensues - restricted blood flow, cardiac ischemia and chest pain, the most
common symptom of ACS.
ACS is divided into three categories: - unstable angina (USA)
Non ST segment elevation MI (NSTEMI)
ST segment elevation MI (STEMI).
unstable angina (USA) - no rise in cardiac biomarkers. If there is a decrease in left
ventricular function secondary to cardiac ischemia, it returns to normal after the
ischemia has resolved.
Non-STEMI
No evidence of ST elevation. - Cardiac biomarker levels rise but the levels will not be
high enough to render a positive test result. May be left ventricular dysfunction after
NSTEMI resolves
STEMI - ST elevations will be present in different leads depending on injury location; a
Q wave may be present. CK-MB and troponin are positive; high risk for left ventricular
dysfunction.
Risk factors for ACS include: - CAD, atherosclerotic plaque on the walls of the arteries;
age >55, Male; smoking, obesity, HTN, ETOH, hypercholesterolemia, sedentary
lifestyle; uncontrolled DM
Myocardial ischemia is characterized by - T-wave inversion on an ECG.
Infarction is characterized by a Q wave duration of 0.04 seconds or longer. - The Q
wave will also be approximately one-fourth to one-third the height of the R wave.
40% to 50% of MIs involve the INFERIOR WALL - In 80% of patients, the inferior wall is
supplied by the RCA via the posterior descending artery (Right-dominance).
Good prognosis (<10% mortality)
40% to 50% of MIs involve the INFERIOR WALL - In the other 20%, the posterior
descending artery is a branch of the circumflex artery (Left-dominance).
40% of INFERIOR WALL MIs involve the RIGHT VENTRICLE - worse outcome
, hypotension, bradycardia, heart block, and cardiogenic shock
Bradycardias, heart blocks and arrhythmias associated with inferior wall MIs - The right
coronary artery perfuse the sinoatrial node and AV node.
Most common ECG finding with inferior wall MI - ST elevation in II, III and aVF
Reciprocal ST depression in lead aVL.
If right ventricular involvement suspected - Performed a "right-sided EKG" by reversing
the precordial leads to the right side of the chest in a mirror image of the traditional
precordial leads.
Suspect right ventricular infarction in ALL inferior wall MIs. Do a right-sided EKG... - ST
elevations is V3R-V6R confirms right ventricular MI
In patients presenting with inferior wall MI, right ventricular infarction is suggested by the
presence of: - ST elevation in V1 (the only lead that looks directly at the right ventricle).
Plus
ST depression in V2 (= highly specific for RV MI).
The ECG findings in occlusion of circumflex artery or branch from the LAD artery - ST
elevations in leads I and aVL,
Reciprocal changes in V1 and V3.
POSTERIOR wall MI - Occlusion in posterior descending artery — a branch of the RCA.
May see inferior MI at same time due to shared blood supply.
The ECG findings in POSTERIOR wall MI - ST Depression in V1-V4
ST elevation in V7-V9 (posterior EKG)
The ECG findings in POSTERIOR wall MI - If R wave > S wave in V1 and V2, possible
occlusion in RCA or circumflex artery.
The ECG findings in POSTERIOR wall MI - ST elevation in II, III and aVF if an inferior
MI is also present.
The ECG findings in POSTERIOR wall MI & Right Ventricle - When there are lead
changes in V4, V5, and V6, it indicates involvement of the right ventricular wall. In this
type of infarct, the right coronary artery is involved, and no reciprocal changes will be
seen.
Anterior wall is affected through an MI, ECG changes include positive - R-wave
progression
ST elevation n V1-V4,
Possible reciprocal changes in leads II, III, and aVF.
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