First Aid 281-285 Cardio

Question 1

Which channel is responsible for phase 0 of SA node AP? What is phase 0?

Answer 1

opening of voltage gated Ca channels; upstroke

Question 2

What are Na channels’ role in phase 0?

Answer 2

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

Question 3

Phase 3 - which channels are operational and which ones are not? Influx/Efflux of which ion?)

Answer 3

Ca channels are now inactivated and there is inc activation of K channels. K efflux

Question 4

Which phase accounts of the automaticity of SA/AV nodes?

Answer 4

Phase 4

Question 5

Which phase is affected by drugs that affect HR?

Answer 5

Phase 4 - slope of phase 4 in SA node determines HR

Question 6

How does SANS stimulation affect HR?

Answer 6

SANS stimulation inc the chances the If channels are open and therefore inc HR

Question 7

Atrila depolarization is reflected in which part of ECG?

Answer 7

P wave

Question 8

Normal duration of PR interval?

Answer 8

<200 msec

Question 9

List the following in order of seep of conduction: atria, ventricles, AV, purkinje fibers

Answer 9

Purkinje > atria > ventricles > AV node

Question 10

Normal duration of QRS?

Answer 10

<120 msec

Question 11

T wave represents which part of cardiac cycle?

Answer 11

ventricular repol

Question 12

U wave caused by?

Answer 12

hypokalemia, bradycardia

Question 13

What does T wave inversion represent?

Answer 13

poss recent MI

Question 14

Which drugs cause long QT?

Answer 14

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

Question 15

Which congenital long QT is more common?

Answer 15

Jervell and Lange-Nielsen (AR)

Question 16

Which congenital long QT syndrome is associated with deafness?

Answer 16

Jervell and Lange-Nielsen

Question 17

ECG pattern of Brugada syndrome?

Answer 17

ECG pattern of RBBB (wide QRS, slurred S, T irreg) + ST elevation ( followed by neg T, esp in V1-V3 ) - Parenthesis = not in FA

Question 18

What is underlying patho mech of WPW syndrome?

Answer 18

Abnormally fast conduction from atria –> ventricle, bypassing the AV node

Question 19

ECG signs of WPW?

Answer 19

delta wave + wide QRS + short PR

Question 20

ECG signs of 1st degree AV block?

Answer 20

prolonged PR (>200msec)

Question 21

ECG signs of 2nd degree AV block, Mobitz I?

Answer 21

progressive lengthening of PR interval until a beat is dropped

Question 22

ECG signs of 2nd degree AV block, Mobitz II?

Answer 22

Dropped beats not preceeded by progressively longer PR internals - can be 2 or more P waves to one QRS

Question 23

Which infectious disease is associated with 3rd degree AV block?

Answer 23

Lyme Disease

Question 24

Recombinant form of B type natriuretic peptide?

Answer 24

Nesiritide

Question 25

Physiological effect of ANP?

Answer 25

Causes vasodilation and dec Na resorption at renal collecting tubule, VD of aff art and VC of eff art

Question 26

ANP uses which 2nd messenger?

Answer 26

cGMP