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Cardiorespiratory PBL > PBL > Flashcards

PBL Flashcards

1
Q

conduction abnormalities

A

these are abnormalities in the way that the electrical impulses travel through the heart

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2
Q

ECG

A

this is an electrocardiogram, which is a test that is done on the hear that looks at the heart rate, rhythm and electrical activity

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3
Q

Rhythm strip

A

this is an overview of the patients ECG which could indicate normal or abnormal conditions this is usually done by looking at Lead II

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4
Q

sinus rhythm

A

– this is a normal heart beat in respect to heart rate and rhythm

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5
Q

P wave

A

this is the wave that shows atrial depolarisation

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6
Q

QRS complex

A

this is the wave that shows ventricular depolarisation

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7
Q

Bradycardia

A

this is abnormal rhythm of the heart when it beats slowly, fewer than 60 beats per minute

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8
Q

Tachycardia

A

this is abnormal rhythm of the heart when it beats faster than normal when at rest, usually over 100 beats per minute

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9
Q

Saw tooth flutter waves

A

characterised by a gradual downward deflection followed by a sharp negative deflection, this is as a result of passive depolarisation of the left atrium, there are more P waves that are seen on the ECG

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10
Q

describe lead I

A
  • Records signal between left and right axillae
  • Shows a lateral view of the heart
  • Smallest amplitude
  • Can’t see Q wave
  • right arm to left arm
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11
Q

describe lead II

A
  • Records signal between right axilla and leg
  • Standard ECG is taken from this lead
  • Shows are inferior view of the heart
  • Biggest positive amplitude
  • right arm to left leg
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12
Q

describe lead III

A
  • Records signal between left axilla and leg
  • Shows an inferior view of the heart
  • Cant see Q wave
  • left arm to left leg
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13
Q

What are the augmented leads

A
  • Unipolar leads
  • Amplitude of the signal is calculated between one physical recording point and a virtual reference point in the middle of the chest
  • Made up of aVR, aVL, aVF
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14
Q

describe aVR

A
  • Largest amplitude for an S wave
  • Large Q wave, small non-existent R wave
  • Recording positive to negative
  • Inverted T wave
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15
Q

describe aVF

A
  • Inferior view of the heart

- Normal

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16
Q

describe aVL

A
  • lateral view of the heart

- very small

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17
Q

what kind of leads are chest leads

A

unipolar leads

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18
Q

describe V1

A
  • Septal view
  • 4th intercostal space on the right
  • Mainly negative and has a large S wave
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19
Q

describe V2

A
  • Septal view
  • 4th intercostal space on the left
  • Less negative than V1 but still quite negative
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20
Q

describe V3

A
  • Anterior view
  • Bipolar
  • between V2 and V4
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21
Q

describe V4

A
  • Anterior view
  • Bipolar
  • 5ht intercostal space midclavicular line
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22
Q

describe V5

A
  • Lateral view
  • Mainly positive as it has a large R wave
  • between V4 and V6
23
Q

describe V6

A
  • Lateral view
  • Mainly positive as it has a large R wave
  • 5 th intercostal space mid axillary line
24
Q

Describe the anatomy of the coronary artery

A

There are two main coronary arteries, these are the right coronary arteries and the left coronary arteries. They both split into two. The LCA arises from the left coronary cusps and the RCA arises from the right coronary cusps
Aortic sinus is made out of the right posterior and left semilunar cusps, the posterior semilunar cusps does not have an coronary artery that supplies it

25
Q

describe the anatomy of the RCA

A
  • Posterior interventricular (PDA)
  • Right marginal
  • Supplies the blood to the right ventricule and atrium, and the SA and AV nodes
26
Q

describe the anatomy of the LCA

A
  • Circumflex – supplies the blood to the outer side and back of the heart
  • Anterior interventricular (LAD) – supplies the blood to the front of the left side of the heart
27
Q

How do you find out what side of the heart is dominant

A
  • If the PDA is from the right coronary artery then you are right dominant
  • If the PDA is from the circumflex of the left coronary artery then you are left dominant
  • Co-dominance occurs when the PDA is from both the right coronary artery and the circumflex of the left coronary artery
28
Q

what is the blood supply to the heart

A
  • LCA supplies 2/3rd of the anterior part of the heart

- RCA supplies 1/3rd of the posterior part of the heart

29
Q

what do coronary veins do

A
  • Collect wastes from cardiac muscle
  • Drains into the coronary sinus on the posterior surface of the heart
  • The coronary sinus then empties into the right atrium therefore acting as the 3rd vein entering the right atrium
30
Q

describe the anatomy of the conducting system of the heart

A
  • Sino- atrial node – this is a group of pacemaker cells that are in the top of the right atrium near the SVC, they cause spontaneous action potentials to develop in the atria causing atrial depolarisation to happen and the walls of the atria to contract.they do this by automaticity
  • SAN is made up of modified cardiac muscle cells and it receives blood from the SAN
  • Connected to adjacent atrial cells by gap junctions, these gap junctions enable the spread of electrical activity from cell to cell
  • Electrical acidity starts in the SA node – spread across the atria to the atrioventricular node where it is stopped as it is not directly transmitted into the ventricles there is a delay of 60ms to allow the atria to contract and push blood into the ventricles before the ventricles start to contract
  • AV node is located on the inter-atrial septum which is close to the tricuspid valve
  • AV is the weak link
  • Muscle fibres leave the AV node and travel down the interventricual septum activating the ventricles, these are purkinje fibres
  • There are two bundles of purkinje fibres these are the left and the right bundles
  • The top of both of the bundles is the bundle of His
31
Q

describe the normal ECG

A
  • P wave – atrial depolarisation 6-11 ms, should be smooth and rounded
  • QRS complex – ventricular depolarisation – should be smaller than 100ms, can be positive, negative or bipolar
  • ST segment – all ventricular muscles are contracting, it normally starts flat and curves upwards into the T wave
  • T wave – ventricular repolarisation
  • PR interval – tells you delay of the AV node, should be about 120-200ms if it is greater than this then there is a heart block
  • Normally recorded from lead 2
32
Q

Describe the action potential of the heart

A
  • Last 200ms which is 100 times longer than a nerve action potential
  • In the cardiac pacemaker cell there is a constant influx of sodium into the cell at rest
  • This would depolarise the cell but the outward potassium current prevents the depolarisation, therefore the generation of an action potential is dependent on the potassium and sodium influx
  • Outward potassium current decays with time so the sodium current becomes more dominant and the membrane potential depolarises slowly
  • Potassium eventually reaches a critically low level and an action potential is generated
  • During the action potential the potassium current is reset to a high level and then starts to decay again
  • Pacemaker cells in the SA are spontaneously active
  • Heart rate depends on the decay of the outward potassium current
33
Q

describe the plateau of the heart action potential

A
  • This is a prolonged depolarisation phase due to the late entry of calcium into the cell allowing the cardiac muscle to contract for longer
  • Calcium enters through L type calcium channels which are slow calcium channels that are found in the membranes of cardiac cells
34
Q

Describe the refractor period

A
  • Also have a long refractory period
  • Prevents muscles from contracting prematurely and inefficiently keeping the cells synchronous
  • Get out of synch and fibrillation occurs
35
Q

what are the types of heart block

A

1st
2nd
3rd

36
Q

describe 1st heart block

A

electrical impulses are slowed as they pass through the conduction system but they all reach the ventricles – rarely causes problems
- PR internal is greater than 200ms

37
Q

describe 2nd heart block

A 
Type 1 (Moblitz I/Wenckebach) – Progressive PR
prolongation until there is a dropped beat
Type 2 (Moblitz II) – Constant PR interval but P wave is
often not followed by a QRS complex
38
Q

describe 3rd heart block

A

none of the electrical impulses from the atria reach the ventricles, therefore the ventricles do not receive electrical impulses from the atria and may generate impulses of their own called junctional escape beats – Patient 1 has 3rd degree heart block
- THERE IS NO ASSOCIATION BETWEEN P WAVES AND QRS COMPLEX

39
Q

what are the causes of heart block

A
  • Congenital heart block – antibodies cross the placenta and damage the babies heart leading to congenital heart block
  • Damage to the heart due to a heart attack – causes damage to the AV node
  • Coronary heart disease
  • Myocarditis
  • Heart failure
  • Rheumatic fever
  • Cardiomyopathy
  • Certain emdicines – beta blockers, calcium channel blockers
  • Overly active vagus nerve can also cause heart block – one vagus nerve on each side of the body this can slow down the heart rate
40
Q

what is the mechanism of causation

A
  • Coronary ischemia – this is a blockage in the right coronary arteries therefore not enough blood goes through the coronary arteries so not enough blood gets to the SAN or the AVN
  • Fatty susbtances can get stuck to the walls of the coronary arteries restricting blood flow – caused by an atheroma
41
Q

what are the symptoms of heart block

A
  • Fainting
  • Dizziness
  • Fatigue
  • Shortness of breath
  • Chest pain
42
Q

what are the treatments of heart block

A
  • This depends on the type of heart block you have
  • First degree – may not need treatment
  • 2nd degree – may need a pacemaker – device placed under your chest or abdomen that uses electrical pulses to prompt the heart to beat at a normal rate
  • 3rd degree – will need a pacemaker, have it for the rest of your life
43
Q

what are the drugs used to treat heart block

A
  • Beta blockers- reduces blood pressure, bind to B1 in the heart reducing the heart rate
  • Calcium ion channel blockers – prevent calcium entering the heart, lowering blood pressure and relaxing and widening vessels
  • Antiarrthymics – beta blockers, block impulses that cause irregular heart rhythm
  • Digoxin – binds to the heart muscle, slows the rate at which the heart beats and increases the force with which the heart muscle contracts with every heartbeat
44
Q

what are the types of atrial flutter

A
  • Paroxysmal atrial flutter – comes and go, last hours or days
  • Persistent atrial flutter – permanent
  • patient 2 has atrial flutter
45
Q

what are the causes of atrial flutter

A
  • Coronary heart disease
  • Cardiomyopathy
  • Heart vavle disease
  • Congenital heart disease
  • Inflammation of the heart
  • High blood pressure
  • Overactive thyroid gland
  • Pneumonia
  • Asthma
  • Lung cancer
  • Diabetes
  • Pulmonary embolism
  • Carbon monoxide poisoning
46
Q

what is the mechanism of action of causation of atrial flutter

A
  • SAN tells atria when to contract, when you have an AFL SAN sends out the electrical signal but part of the signal travels in a continuous loop along the pathway on the right atrium causing the atria to contract rapidly
  • This can be caused by coronary artery disease and open heart surgery
47
Q

what are the symptoms of atrial flutter

A
  • Dizziness
  • Shortness of breath
  • Noticeable heart palpitations
  • Tiredness
48
Q

what are the consequences of atrial flutter

A
  • Lead to stroke – upper chambers do not pump efficiently lead to blood clots forming, move into the lower chambers of the heart and get pumped into the blood supply to the lungs, clots cause a stroke
  • Heart failure – heart unable to pump blood around efficiently any more
49
Q

what is the treatment of atrial flutter

A
  • Beta blockers n- block actions on SA and AV nodes increasing refractory period slowing the intra-cardiac conduction of the cardiac action potential via sodium channel effects
  • Calcium channels blockers
  • Antiarrhythmic medicines
  • Digoxin – takes several weeks to become effective,
  • pacemaker
50
Q

How to interpret an ECG

A
  1. calculate heart rate
  2. calculate rhythm
    - measure the distance between consesucitve RR intervals
  3. check P waves - absent or present, followed by QRS complex
  4. Check PR interval - normally 120-200ms
  5. Check QRS complex, with normal 120ms
  6. check ST segment
    - elevation - greater than 1mm
    - depression greater than 0.5mm
  7. Check T waves
    - tall if greater Tham 5mm in limb leads and greater than 10mm in chest leads, inverted
51
Q

what is the ECG appearance of atrial flutter

A

Sawtooth appearance

Atrial rate around 300/min

52
Q

how does atrial flutter differ from atrial fibrillation

A

Absent P waves in AF

Atrial rate 400-600/min in AF

AF is always irregularly irregular

53
Q

define atrial flutter

A

Form of supraventricular tachycardia, characterized

by a succession of rapid atrial depolarisation waves

Cardiorespiratory PBL (5 decks)

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