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KIN103 > cardiovascular physiology: ECG pathophysiology > Flashcards

cardiovascular physiology: ECG pathophysiology Flashcards

1
Q

what is the order of electrical conduction through the heart

A

sa, internodal pathways, av, av bundle, bundle branches, purkinje fibres

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2
Q

where are the autorhythmic cells located in the heart

A

sa node, av node, purkinje fibres

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3
Q

what mechanical event initiates during the latter part of the P wave and continues throughout the p-r segment

A

atrial systole

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4
Q

what mechanical event initiates just after the Q wave and continues throughout the the s-t segment

A

ventricular systole

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5
Q

what electrical event occurs during the T wave of an ECG

A

ventricular repolarization

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6
Q

what signals does the vagus nerve carry?

A

parasympathetic

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7
Q

what 2 forces are balanced to control HR

A

parasympathetic, sympathetic

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8
Q

what is vagus withdrawal and what does it cause

A

decrease in parasympathetic activity, increase in HR

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9
Q

one little square of the ECG corresponds to what length of time?

A

.04 sec

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10
Q

one large square of ECG corresponds to what length of time?

A

.2 seconds

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11
Q

What is the purpose of an ECG

A

used to test for clinical abnormalities

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12
Q

if the P-R segment of the ECG is abnormal, what could be going wrong

A

AV node and Av bundle conductivity

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13
Q

what are intervals?

A

combination of segments and waves

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14
Q

What does the PR interval represent

A

the time between atrial depolarization and ventricular depolarization

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15
Q

what does the QT interval represent

A

it represents the time between when the ventricles start depolarising and when they finish repolarizing

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16
Q

What is Einthoven’s triangle

A

it consists of a pair of electrodes being placed in both arms and a leg. Each pair of electrodes between limbs represents a lead.

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17
Q

What is Einthoven’s triangle lead 1?

A

it is between the electrodes placed on each arm. The left corresponds with a positive charge. Right is a negative charge.

18
Q

when a downward deflection is recorded on an ECG what does this mean.

A

it means a current is flowing towards the negative lead (right side).

19
Q

when a upward deflection is recorded on an ECG what does this mean?

A

it means a current is flowing towards the positive lead ( left side).

20
Q

if the R wave of a ECG is unusual, what is the mechanical event that is correspondingly unusual?

A

Ventricular systole

21
Q

What is the normal range of HR

A

60-100 bpm

22
Q

How do you calculate HR from an ECG?

A

1500/# of small squares between R waves

23
Q

What is tachycardia

A

HR>100 at rest

24
Q

what is bradycardia

A

HR<60 at rest

25
Q

what does the presence of arrhythmias indicate?

A

It can indicate the presence of electrical generation or conductive problems.

26
Q

what is atrial fibrillation, its symptoms and what does it look like on an ECG

A

it is when the SA node is not acting as a pacemaker.

On the ECG it looks like the p wave is replaced with very little and frequent irregular spikes.

can have no symptoms but can also be associated with classic symptom of heart failure

27
Q

What is a PVC and what are its symptoms and ECG pattern

A

A premature ventricular contraction is when there are extra beats that originate from outside of the SA node.

on an ECG, the QRS complex and t wave look abnormal.

it can feel like a skipped beat and can also cause heart failure symptoms

28
Q

When do PVCs need to be treated?

A

when they occur more than 6 a minute

29
Q

Several PVCs in a row at more than 120bpm is called what

A

ventricular tachycardia VT

30
Q

describe ventricular flutter

A

A form of VT but at increased HR of 250-350bpm
no discernable QRS complex or T waves
looks like a sine wave in an rapid organised rhythm

31
Q

what can VT progress into

A

Ventricular fibrillation

32
Q

what’s the difference between ventricular flutter and ventricular fibrillation

A

ventricular flutter is still organised. ventricular fibrillation is uncoordinated and unable to push blood.

33
Q

describe ventricular fibrillation (VF)

A

uncoordinated contraction of the ventricles. the contractions are too weak to eject blood into the aorta

34
Q

What can an S-T elevation indicate?

A

Myocardial infarction (heart attack)

35
Q

What can an S-T depression indicate

A

Myocardial ischemia (obstructed blood flow in the coronary arteries by atherosclerosis. if they rupture then myocardial infarction may occur)

36
Q

what is a first degree AV block and what does it look like on an ECG graph

A

it looks like an increase in duration of the PR interval. To count as a first degree AV block then the delay must be longer than .2 sec. This is caused by reduced conduction in between the two nodes.

37
Q

What is a Second degree AV block and what does it look like on an ECG graph

A

It’s when there is a skipped ventricular contraction every 2-5 beats. this looks like a missing QRS complex every 2-5 beats. This is due to a slowed and sometimes blocked conduction to the AV node meaning it is sometimes disconnected from the SA node.

38
Q

describe a third degree AV block and what does it look like on an ECG graph.

A

It is when there is no more conduction or communication in-between the two nodes. this means that atrial and ventricular contractions happen independent of one another and not coordinated as they are supposed to be. This will look like the P wave and QRS complex happening at different rates.

39
Q

How is bradycardia most commonly corrected?

A

It is corrected through the placement of an artificial pacemaker

Bradycardia: resting HR<60bpm

40
Q

How is tachycardia most commonly corrected?

A

Medication

Cardioversion
(electrical shock therapy or defibrillation can help reset heart rhythm)
Ablation therapy (destruction of cardiac tissue responsible for arrhythmia)

41
Q

what are other examples of treatments for arrhythmias?

A

surgery
-Coronary artery bypass
-maze procedure

Implantable Cardioverter-Defibrillator (ICD)
-corrects bradycardia like a normal pacemaker
-can act as defibrillator if VT or VF detected

KIN103 (9 decks)

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