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Cardio > Lecture #4 > Flashcards

Lecture #4 Flashcards

1
Q

What is reentry?

A

In certain pathological conditions, a wave of depolarization may (instead of dying out) keep going on brancing or circular pathways in the myocardium

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2
Q

In the loop of muscle setting, what three conditions favor re-entry?

A

Long Pathway
Reduced Conduction Velocity
Shortened Refractory Period

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3
Q

Reentry in the heart typically occurs under what 4 conditions?

A

Long Pathways
Variable Conduction Rates
Altered Repolarization Rates
Aberrant Pathways

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4
Q

Example of long pathways in a heart

A

Dilated atria/ventricles

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5
Q

What might cause variability in conduction rate of the heart?

A

Ischema/Injury

Hyperkalemia/Cocaine

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6
Q

Altered repolarization tends to lead to what effect? What might cause it?

A

Shortened refractory period

Catecholamines

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7
Q

What might cause an abberant pathway in the heart?

A

A tract (bunde of kent) that bypasses AV

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8
Q

Relationship of ischemia/injury/fibrosis to reentry?

A

Can form a slowly conducting region that holds charge while surrounding tissue repolatizes, causing an ectopic beat

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9
Q

A series of ectopic beats can lead to a…

A

ventricular tachycardia

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10
Q

What is AV nodal reentry? What pathways are included?

A

Two pathways develop in AV
Slowly conducting with a short refractory
Rapidly conducting with a long refractory

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11
Q

Describe the process of AV renodal reentry.

A

Conduction through fast pathway
Slow conduction pathway can retrograde up repolarized fast path
Slow conduction pathway restimulated by restim fast path
AV reentrant tachycardia

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12
Q

What EKG findings for wolf-parkinson-white syndrome?

A

Short P-R and pre-excitation wave slurring the upstroke of the QRS

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13
Q

What happens in WPW syndrome?

A

an aberrant muscular bridge, the Bundle of Kent, connects the atria and ventricles, bypassing AV

Causes tachycardia that impairs ventricular filling
Dizziness, Faiting, and Angina

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14
Q

What is a delta wave?

A

A pre-excitation wave on the upstroke of QRS.

Shows rapid ventricular activation.

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15
Q

If premature atrial depolarization occurs with the accessory pathway still refractory, but AV not…

Causes….

A

first impulse passes antergrade through the excitable AV and vent, accesory recovers and causes delayed atrial stim

Inverted P-Wave, Paroxysmal supraventricular tachycardia

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16
Q

EKG findings in Lown-Ganong-Levine syndrome

A

Short PR

Normal ORS

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17
Q

What are triggered events?

A

Abnormal depolarizations always coupled to preceding action potential.

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18
Q

Difference between early-afterpolarization and delayed afterpolarization.

A

EAD’s occur before the cell is fully repolarized

DAD’s occur after the cell is fully repolarized.

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19
Q

When would you see EAD’s?

A

LQTS (often from mutation or drug use)

20
Q

What are DAD’s assocaited with?

A

Calcium Overload

Seen in high HR, digitalis toxicity, high extracellular Ca ion conc, prolonged catecholamines

21
Q

How does calcium overload trigger DADs?

A

Activates Ca/Na antiporter

Large amount of Na driven in depolarizes mem

22
Q

How do you inhibit DADs?

A

Ca channel blockers, beta blockers, ryanodine

23
Q

Review EKG notes.

A

Because you’re worth it too.

24
Q

How might one use an EKG to identify the culprit artery in a myocardial infarction?

A

Use extra leads

Move V3-5 right, add V7-9 on back, etc.

25
Q

What will increase the height of R Wave?

A

Hypertrophy of Ventricle (from high MAP or aortic stenosis, or hypertension)

26
Q

What will cause decreased voltage on EKG? (3)

A
  1. decreased muscle mass (old heart attack)
  2. Shunting out of current (fluid in pericardial space)
  3. Changes of intrathoracic resistance (emphysema)
27
Q

What do vector arrows point to (electrically)

A

Area to be depolarized

28
Q

What are vectors?

A

Arrows that depict direction and megnitude of equivalent dipoles

29
Q

Explain cardiac vector loop

A

Instantaneous cardiac vector inscribes a loop as the tissue is depolarized

30
Q

Why is ventricular repolarization the same direction as R wave?

A

Outer/Apical surfaces of the heart repo before the inner/basal due to high pressure inhibiting coronary flow to endo and repo.

(Vector is always pointing bottom left, so always positive)

31
Q

The form of the EKG in the precordials is determined by….

A

Cardiac axis in the transverse plane

32
Q

What do you see in an EKG transition point?

A

Equal positive and negative waves in QRS

33
Q

Not counting precordials, all other leads are in the _____ plane.

A

Frontal

34
Q

A net positive QRS means that the axis is directed where?

A

toward the positive pole of the lead

35
Q

Transition point means axis is….

A

at right angles to the lead

36
Q

Alternate method of reading an EKG?

A

two leads with QRS of equal size

Axis is in the middle

37
Q

What is normal axis deviation?

A

-30 to 120

38
Q

What might cause someone to be left axis deviated? (5)

A 
COPD
Extreme Obesity
Left Anterior Hemiblock
Pathologic Q Waves
Left Ventricular Hypertrophy (Only in transverse plane)
39
Q

Causes of right axis deviation?

A

Right ventricular hypertrophy

Left anterolateral myocardial infarction

40
Q

Leads associated with lateral heart (L Circumflex and LAD)?

A

I, AVL, V5, V6

41
Q

Leads associated with septum?

A

V1, V2

42
Q

Leads associated with anterior heart?

A

V2, V3, V4

43
Q

Leads associated with inferior heart (Right Coronary)?

A

II, III, aVF

44
Q

What does ST elevation in II, III, and aVF indicate?

A

Inferior Wall Infarction

45
Q

What would be required to really see a true posterior infarction?

A

V7-9

46
Q

Why is seeing this infarction not necessarily a huge concern?

A

Posterior infarction typically accompanied by infarctions elsewhere, often inferior wall

Cardio (10 decks)

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