Master the board step 3

Master the Boards: USMLE Step 3
Basic Science Correlate
Mechanism of Calcium Blockers: Why They Don’t Work in PAD
Beta blockers are not
contraindicated with PAD.
If the patient needs them
for ischemic disease, they
should be used.
In PAD, the atherosclerotic obstruction is on the inside the vessel. Calcium
blockers dilate the muscular layer, which is exterior to the atherosclerosis in
the center. Dilating the outer layer does not expand the inside.
CCS Tip: On CCS, move the clock forward several weeks. PAD is not an emergency!
If initial therapies do not work and the pain progresses, or there are signs of
ischemia such as gangrene or pain at rest, then perform surgical bypass.
Rhythm Disorders
Atrial Fibrillation (A-Fib)
A-fib presents with palpitations and an irregular pulse in a person with a
history of hypertension, ischemia, or cardiomyopathy.
Diagnostic Testing
If the initial EKG does not show the answer, a patient in the hospital should
be placed on telemetry monitoring. Outpatients who are hemodynamically
stable should undergo Holter monitoring, which is continuous, ambulatory
cardiac rhythm monitoring for 24 hours or longer.
CCS Tip: For CCS cases, other tests to order once A-fib is found on EKG are the
following:
CHADS
C = CHF
H = Hypertension
A = Age > 75
D = Diabetes
S = Stroke or TIA
CHADS score of 0 – 1
needs aspirin. At 2 or
more, use warfarin,
dabigatran, rivaroxaban, or
apixaban.
··
Echocardiography: Looking for clots, valve function, and left atrial size
··
Thyroid function testing: T4 and TSH levels
··
Electrolytes: Potassium, magnesium, and calcium levels
··
Troponin or CK-MB levels: These may be appropriate to test in some
acute-onset cases.
Treatment
Unstable patients should undergo immediate synchronized electrical cardioversion.
Unstable patients should be cardioverted with the first screen, without
waiting for TEE or anticoagulation with heparin or warfarin. Instability is
defined as a systolic blood pressure < 90, congestive failure, confusion related
to hemodynamic instability, or chest pain.
Stable patients should have their ventricular heart rate slowed if it is > 100–110
per minute.
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