Cardiac Flashcards

1
Q

What is afterload?

A

The pressure the heart must overcome to eject the blood from its ventricle. (Corresponds to the systolic blood pressure). As afterload increases (the force required to pump blood from the heart) cardiac output decreases.

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2
Q

What is myocardial ischaemia?

A

When the hearts oxygen and nutrients demand exceeds the amount that can be supplied by the arteries, usually due to stenosis or a build up of plaque. This can result in chest pain and usually occurs during exercise or periods of increased preload or afterload.

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3
Q

Why does GTN help myocardial ischemia?

A

It reduces cardiac workload. It does this by causing venous dilation and therefor peripheral venous pooling. Venous pooling results in a decrease in pressure in these vessels and therefore decreases venous return, ventricular filling and cardiac out put. This decreased cardiac output causes less work for the heart and therefore less oxygen is required by cardiac tissues.

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4
Q

What is the maximum dose of GTN?

A

0.8mg (2 sprays) every 2-5 minutes with reassessment of vitals

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5
Q

How does GTN reduce cardiogenic pulmonary oedema?

Venous dilation.

A

Venous dilation causes peripheral pooling of blood. This reduces the amount of blood returning to the heart from the veins and reduces preload. This then reduces the amount of blood being pumped into the pulmonary blood vessels, decreasing the pressure within them.

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6
Q

How does GTN reduce cardiogenic pulmonary oedema?

Aterial dilation

A

Dilation of arteries/arterioles reduces total peripheral resistance and therefore afterload. Because peripheral resistance has decreased the heart can more easily eject blood into the systemic circulation decreasing the volume and pressure within the pulmonary vessels.

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7
Q

What are the contraindications of GTN?

A

Systolic BP of less than 100mmHg
HR of less than 40bpm
HR of greater than 130bpm

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8
Q

What are the contraindications of GTN?

A

Right ventricular infarct
Poor Perfusion
Dysrhythmia
Erectile dysfunciton

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9
Q

What are the function of platelets (thrombocytes)?

A

Transport of chemicals important to the clotting process. By releasing enzymes and other factors platelets help initiate and control the clotting process.
The formation of a temporary patch in the walls of damaged blood vessels by clumping together to form a plug.
Active contraction after clot formation had occurred. Platelets contain filaments of actin and myosin. Once the clot has formed these filaments contract to reduce the size of the break in the vessel wall.

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10
Q

What factors are released in response to endothelial damage (to initiate clotting)?

A

Adrenaline
Serotonin
Thromboxane A2
Platelet activating factor

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11
Q

What does acute coronary syndrome (ACS) refer to?

A

NSTEMI
STEMI
unstable angina

It is almost always associated with rupture of an atherosclerotic plaque and partial or complete thrombus (blood clot) in the infarct related artery.

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12
Q

How does aspirin work?

A

Acts on cyclo-oxygenase-1 to reduce the amount of prostaglandins and therefore the amount of throboxane A2 produced. This reduces platelet activation and aggregation.

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13
Q

What is the clinical presentation of myocardial ischaemia?

A

Chest pain, described as a pressure or heavy sensation. Brought on or made worse by exertion.

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14
Q

Who are at risk of a silent MI?

A

Diabetics and the elderly.

May present with shortness of breath, fatigue, weakness, non-specific unwellness or light headedness.

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15
Q

What dose of aspirin do we give for MI?

A

300mg once
chewable
do not dissolve in water.

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16
Q

What is the P wave?

A

Represents the depolarisation of the atria.

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17
Q

What is the PR interval?

A

Measured from the beginning of the P wave to the beginning of the QRS complex. Normal PR interval is 0.12-0.20 seconds.

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18
Q

What does a prolonged PR interval usually indicate?

A

a block of the impulse, so a heart block.

19
Q

What is the QRS complex?

A

Measured from the beginning of the Q wave to the end of the S wave. Duration should be less than 0.12 seconds.

20
Q

What is the T wave?

A

Denotes the repolarisation of the ventricles.

21
Q

What is the ST segment?

A

the interval between the end of the QRS complex and the start of the T wave.

22
Q

Why does we use 12 leads?

A

Reduces time to definitive therapy
helps in predication of common complications unique to infarct location
Helps recognise and avoid some hidden perils in treatment of some MI
Provides a baseline for serial ECG evaluations

23
Q

When should we use a 12 lead?

A

Classic cardiac presentation (or what you believe to be cardiac)
Tachycardia, bradycardia or dysrythmia on a 3 lead
When you believe a 12 lead will add to the assessment of the patient.

24
Q

When should you not use a 12 lead?

A

When the condition of your patient is life threatening or severely compromised
When taking the 12 lead will result in delays in either treatment or transportation
When taking the 12 lead will not result in added value to your assessment.

25
Q

Where is V1 placed?

A

Find the angle of Louis
Directly lateral is the second rib
below this is the second intercostal space.
move down to the fourth ICS on the right side of the sternum.
Place V1.

26
Q

Where is V2 placed?

A

Move to left side of sternum

Place V2 on the fourth intercostal space here.

27
Q

Where do we place V3?

A

Halfway between V2 and V4

28
Q

Where do we place V4?

A

Move down to 5th ICS
Move to midclavicular line
Place V4 here

29
Q

Where do we place V5?

A

In the anterior axillary line
usually midway between V4 and V6
V4 V5 V6 should end up in a line along the 5th ICS

30
Q

Where do we place V6?

A

Move along the 5th ICS to the mid axillary line

Place here

31
Q

Which leads show an anterior view?

A

V3-V4

32
Q

Which leads show a septal view?

A

View similar to anterior

V1-V2

33
Q

Which leads show a lateral view?

A

1, aVL, V5-V6

34
Q

Which leads show and inferior view?

A

2, 3, aVF

35
Q

What does the right coronary artery supply?

A

Right Ventricle
Inferior wall of left ventricle
Posterior wall of left ventricle

36
Q

What does the left coronary artery supply?

A

Septal wall of left ventricle
Anterior wall of left ventricle
Lateral wall of left ventricle
Posterior wall of left ventricle

37
Q

What are some possible causes of baseline wander?

A

Patient movement
Poor skin preparation (shaving)
Respiratory interference
Lead wire movement

38
Q

What is preload?

A

The stretch on the ventricle at the end of diastole. I.e. it is related to end diastolic volume. The greater the EDV the greater the stretch and therefore the greater the contraction (within limits)

39
Q

What do we consider severely compromised?

A
Severe hypotension/unrecoverable bp
Inability to obey commands
Severe shortness of breath
Anyone who 'looks status 1'
Anyone at risk of cardiac arrest without intervention
40
Q

What is moderately compromised?

A

Hypotension or prolonged cap refill time
Altered level of consciousness but ability to obey commands
Moderate shortness of breath
Significant symptoms of myocardial ischaemia
Anyone who ‘looks status 2’

41
Q

What is mildly compromised?

A

Near normal bp/CRT
Normal level of conscious
Near normal breathing
Mild symptoms of myocardial ischemia

42
Q

What is the treatment plan for bradycardia?

A

Acquire 12 lead

Gain IV access (para) and ICP backup if required for pacing (if there is compromise)

43
Q

What is bradycardia most commonly caused by?

A

Myocardial ischaemia, particularly when the SA or AV node is ischaemic. Inferior myocardial ischemia is much more likely to involve these nodes than anterior or anterolateral myocardial ischaemia.

Structural heart disease involving the SA node, AV node of the conduction system