First Aid 281-285 Cardio Flashcards
Which channel is responsible for phase 0 of SA node AP? What is phase 0?
opening of voltage gated Ca channels; upstroke
What are Na channels’ role in phase 0?
None, Fast voltage gated channels are permanently inactivated here bc of the resting voltage of these cells is closer to zero than in ventricular myocytes
Phase 3 - which channels are operational and which ones are not? Influx/Efflux of which ion?)
Ca channels are now inactivated and there is inc activation of K channels. K efflux
Which phase accounts of the automaticity of SA/AV nodes?
Phase 4
Which phase is affected by drugs that affect HR?
Phase 4 - slope of phase 4 in SA node determines HR
How does SANS stimulation affect HR?
SANS stimulation inc the chances the If channels are open and therefore inc HR
Atrila depolarization is reflected in which part of ECG?
P wave
Normal duration of PR interval?
<200 msec
List the following in order of seep of conduction: atria, ventricles, AV, purkinje fibers
Purkinje > atria > ventricles > AV node
Normal duration of QRS?
<120 msec
T wave represents which part of cardiac cycle?
ventricular repol
U wave caused by?
hypokalemia, bradycardia
What does T wave inversion represent?
poss recent MI
Which drugs cause long QT?
AntiArrythmics (Class Ia, III)
Antibiotics (Macrolides - and not an antibiotic but also the HIV anti viral rx Protease inhbitors and anti- malaria Chloroquine)
Anti”C”ychotics (haloperidol, Risperidone)\
AntiDepressants - TCAs
Anti-Emetics - Odansetron
Which congenital long QT is more common?
Jervell and Lange-Nielsen (AR)
Which congenital long QT syndrome is associated with deafness?
Jervell and Lange-Nielsen
ECG pattern of Brugada syndrome?
ECG pattern of RBBB (wide QRS, slurred S, T irreg) + ST elevation ( followed by neg T, esp in V1-V3 ) - Parenthesis = not in FA
What is underlying patho mech of WPW syndrome?
Abnormally fast conduction from atria –> ventricle, bypassing the AV node
ECG signs of WPW?
delta wave + wide QRS + short PR
ECG signs of 1st degree AV block?
prolonged PR (>200msec)
ECG signs of 2nd degree AV block, Mobitz I?
progressive lengthening of PR interval until a beat is dropped
ECG signs of 2nd degree AV block, Mobitz II?
Dropped beats not preceeded by progressively longer PR internals - can be 2 or more P waves to one QRS
Which infectious disease is associated with 3rd degree AV block?
Lyme Disease
Recombinant form of B type natriuretic peptide?
Nesiritide
Physiological effect of ANP?
Causes vasodilation and dec Na resorption at renal collecting tubule, VD of aff art and VC of eff art
ANP uses which 2nd messenger?
cGMP
