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ILA formatives > ILA3 - Chest pain > Flashcards

ILA3 - Chest pain Flashcards

1
Q

What is the difference between ischaemia and infarction?

A

Ischaemia is lack of oxygen to tissues but without cell death, so is usually painful under exertion but settles down. Infarction is tissue death from lack of oxygen.1

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2
Q

What is heart failure?

A

Failure of the heart to pump enough blood around the body at the right pressure. There are 3 types:
-Systolic (reduced contractile force of ventricles, LVSD)
-Diastolic (ventricle is non-compliant (stiff) resulting in
reduced left ventricular filling. i.e. ventricle cannot fill
fully and, due to Starling’s law, the force of the
contraction is reduced, HFpEF)
-Diseased or damaged valves

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3
Q

What is cardiac output (and equation)?

A

Volume of blood ejected by the heart in one minute (around 5.7 litres a min)
CO=Stroke volume x heart rate

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4
Q

How is cardiac output measured?

A

Measured by injecting tracer and watch dilution over period of time. Rate of dilution gives rate of flow

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5
Q

What is stroke volume?

A

Amount of blood pumped out by left ventricle in one contraction

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6
Q

What factors can affect heart rate?

A

Sympathetic (stimulates pacemaker cells) and parasympathetic (decreases stimulation of pacemaker) innervation. Hormones (eg. adrenaline) and in stress (lack of oxygen).

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7
Q

What factors affect stroke volume?

A

Health, peripheral vascular resistance, cardiac hypertrophy, cardiac elasticity, blood pressure, diastolic volume, elasticity of blood vessels, salt and alcohol intake, long term sleep deprivation and diabetes

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8
Q

How can an increased BP lead to heart failure?

A

Increased BP = harder to push bloop round body = over time, cardiac hypertrophy = excess hypertrophy and reduced diastolic filling. Due to Starling’s Law stroke volume will then decrease meaning heart can not pump enough blood round the body at the right pressure.

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9
Q

What is Poiseuille’s law?

A

Pi x P x r4 Q=flow rate, p=pressure, r=radius
Q=_________ n= fluid viscosity, l= length
8 x n x l

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10
Q

Equation for blood pressure?

A

BP= total peripheral resistance x cardiac output

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11
Q

Examples of vasodilators

A

NO, CO2, decrease in O2 (systemic), inflammatory mediators, ANP

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12
Q

Examples of vasoconstrictors

A

Sympathetic, ADH, angiotensin II, adrenaline

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13
Q

Breifly describe Starling’s law

A

Sates that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant
Increased volume of blood stretches the ventricular wall causing cardiac muscle to contract more forcefully

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14
Q

What is preload ?

A

The end diastolic volume, a decrease = decreased SV

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15
Q

What is afterload?

A

The pressure which the heart must overcome to pump blood out, increase = decreased SV

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16
Q

What impact does heart failure have on Frank-Starling law of the heart?

A

Law is and overloading of blood into ventricles triggers increased contraction to raise CO. In heart failure this mechanism fails due to weakened cardiac muscles which results in a failure of the heart to pump an adequate amount of blood.

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17
Q

How does a heart attack lead onto symptoms of breathlessness and oedema in the future?

A

Heart attack leads to weakening of myocardium. This results in heart failure. Results in back flow and decreased flow in veins, leading to increased volume of interstitium in lungs (pulmonary oedema, so breathlessness) and the limbs

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18
Q

How can heart failure lead to increased EDV?

A

Weaker myocardium, titin in sarcomere breaks so heart stretches more and cant return to original volume.

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19
Q

What happens during left ventricular contraction?

A

Isovolumetric contraction ( b )
-AV valve closes when the ventricular pressure exceeds atrial pressure.
-Ventricle pressure increases rapidly as the aortic valve is not open.
-No change in ventricular volume but increase in pressure
Maximal ejection ( c )
-Ventricular pressure exceeds pressure in the aorta.
-Aortic valve opens
-70% of total blood, 30% remains in the ventricle
-Calcium is pumped out and Actin is blocked

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20
Q

What happens during left ventricular relaxation?

A

Start of relaxation and reduced ejection ( d ):
-AV remains closed
-Repolarisation leads to decline in pressure and
contraction
-Rate of ejection falls
Isovolumic relaxation ( e ):
-Mitral and aortic valve closed. Volume is constant
-Volume of blood that remains is the end-systolic
volume
Myocardial perfusion occurs mainly during heart relaxation
Rapid LV filling and LV suction ( f )
-Ventricular pressure falls below the atrial pressure
-AV valves open
-Passive ventricular filling
Slow LV filling (diastasis) ( g )
-Increasing pressure in the ventricle as blood flows in. -Reduced pressure gradient
-Rate of filling falls
Atrial booster ( a ).
-Atrial wall contracts: rapid filling

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21
Q

Where does the right coronary artery arise from?

A

Anterior aortic sinus.

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22
Q

Where does the RCA run?

A

Right atrioventricular groove

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23
Q

What branches does the RCA form?

A

Right marginal and (90%) posterior interventricular artery (aka posterior descending artery). Sinoatrial artery (60%)

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24
Q

What does the right marginal artery supply?

A

Inferior part of RV and apex

25
Q

What does RCA supply?

A

Right atrium and ventricle

26
Q

What does the sinoatrial artery supply?

A

SA node

27
Q

Branches of LCA?

A

Left anterior descending and circumflex (left marginal posterior interventricular (30%) and sinoatrial (40%) are branches of circumflex)

28
Q

What percentage of hearts have co-dominance of PIV artery?

A

20%

29
Q

Where does the LCA arise from

A

posterior aortic sinus

30
Q

Which groove does LCA lie in

A

Left atrioventricular sulcus

31
Q

Which artery supplies the AV node?

A

PIV artery

32
Q

Where does the LAD lie (aka ant. interventricular)?

A

Interventricular sulcus

33
Q

What does the LAD supply?

A

Septal branches (2/3 of blood supply), and diagonal branches ( lateral wall of the left ventricle and the anterolateral papillary muscle).

34
Q

What does the PIV supply?

A

Inferior septum (1/3 of its blood supply), the left ventricle and AV node

35
Q

What does the circumflex supply?

A

Gives rise to marginal arteries as it curves towards posterior of the heart.
Supplies posterolateral left ventricle and the anterolateral papillary muscle.

36
Q

What is the order of venous drainage from the heart?

A

Thebesian veins to larger veins (5 main ones) into coronary sinus into right atrium

37
Q

What are the five main tributaries of coronary sinus?

A

Great cardiac vein, small cardiac vein, middle cardiac vein, left marginal vein and left posterior ventricular vein

38
Q

General problems with coronary arteries?

A

Occlusions of the coronary arteries result in ischaemic
heart disease
Atherosclerotic narrowing of the coronary arteries
(coronary artery disease-CAD)
As vessels narrow the heart tissue that it delivers to is
at risk of ischaemia-episodes of insufficient oxygen
delivery to meet its metabolic demands
Ischaemia may manifest as angina, acute coronary
syndromes, heart failure, arrhythmias or sudden death

39
Q

Which artery is most commonly occluded (aka “the widow maker”)?

A

LAD

40
Q

Which territories will be effected with a LAD occlusion?

A

Left and right ventricle and interventricular septum

41
Q

What are the symptoms of LAD occlusion?

A

If completely occluded it will often cause a massive heart attack as large areas of tissue are starved of oxygen and nutrients leading to sudden death
The more proximal the occlusion the more severe the MI (greater area of heart blocked from blood supply)
Typically results in infarction of the anterior wall of the left ventricle
St segment elevations in inferior and leads and ST segment depression in anterior leads

42
Q

What would the affect of a LAD occlusion be on the conducting system?

A

Bundle branches of the conduction system are contained in the septum. Blockage of the artery can lead to impairment or death of the conducting system
This is known as right or left bundle branch block
Condition in which there’s a delay or obstruction along the pathway that electrical impulses travel to make your heart beat. The delay or blockage may occur on the pathway that sends electrical impulses to the left or the right side of the bottom chambers (ventricles) of your heart.
Right: Right ventricle not activated but left is normal
Left: Left ventricular activation is delayed. Let ventricle contracts far later than right
Can result in arrhythmias

43
Q

Which territories would be effected by occlusion of RCA?

A

SA node (Sinoatrial nodal), right ventricle (right marginal), RV, LV, interventricular septum (Posterior interventricular), AV node (AV nodal)

44
Q

What is the effect on the conducting system of a RCA occlusion?

A

Supplies AV node in 100% of people and SA node in 60% of people
Blockage of vessels can therefore lead to death of myocardium at nodes and so result in impairment or loss of conducting system
Can result in Arrhythmias

45
Q

What are symptoms of RCA occlusion?

A

Sometimes problems go unnoticed due to lack of symptoms, shortness of breath,palpitations, faster heartbeat, dizziness, nausea, extreme weakness and sweating

46
Q

What is angina?

A

Pain or discomfort in the chest which may radiate out to the arms neck, jaw or teeth

47
Q

What is stable angina?

A

Provoked by exertion or emotion
Symptoms relieved by rest
Usually when blood flow is only impaired at times of
increased heart rate i.e. supply is sufficient when at rest

48
Q

What is variant angina?

A

Rare disease in which there is a random vasocspasm in the coronary arteries leading to constriction and decreased flow when at rest

49
Q

What is unstable angina?

A

New onset angina at rest

ST segment depression, troponin I and T are normal

50
Q

What is myocardial infarction?

A

Occurs when heart muscle dies due to myocardial ischaemia
Detected by cardiac markers Troponin T and Troponin I
-These proteins are part of the contractile apparatus
within myocytes.
-Detected in blood stream following myocardial injury
Non-ST elevation MI
-ECG is normal (or shows ST depression or T wave
inversion BUT no ST elevation)
-Troponin T or I conc is elevated
-Low probability of acute total occlusion of an important
coronary artery
ST elevation MI
-Acute occlusion of one of the three major epicardial
coronary arteries or its major side branch
-Tissue death occurs within 15-30 mins of vessel
occlusion

51
Q

What do you need to remember?

A

To have fun and love yourself

52
Q

What is arrhythmia?

A

Heart rhythm problems

Atrial fibrillation, Supraventricular tachycardia, Bradycardia, Ventricular fibrillation

53
Q

What are the levels of heart block (arrhythmia)?

A

Severity 1: Split second delay in time taken to pass through AV node. Rarely noticeable symptoms
Severity 2: Series of increasing delays in time taken for AV node to send pulse to ventricle
Severity 3: No transmission of impulses between atria and ventricles through the AV node

54
Q

What lifestyle advice would you give?

A

Quit smoking, reduce alcohol, increase exercise, watch sodium in diet, no go to high altitude or high humidity, lose weight …..

55
Q

What impact does the sympathetic NS have on BP?

A

Increases. Decreases peripheral blood vessel diameter, meaning increased systemic vascular resistance and so increased BP

56
Q

Which coronary artery is also known as the Widow maker?

A

LAD

57
Q

Which nerve innervates the pericardium?

A

Phrenic (C3-5). The dermatome for these roots is neck, shoulder and arm (so pain felt here)

58
Q

What are the typical EDV and ESV?

A

120ml and 50ml

ILA formatives (10 decks)

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