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Clinical Chemistry > L.15 Cardiac Enzymes > Flashcards

L.15 Cardiac Enzymes Flashcards

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1
Q

What is the pathway of blood flow returning from the body?

A

Superior and inferior vena cava → right atrium → tricuspid valve → right ventricle

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2
Q

What is the pathway of blood flow from the right ventricle to the lungs?

A

Right ventricle → pulmonary valve → pulmonary artery → lungs

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3
Q

What is the pathway of blood flow returning from the lungs?

A

Pulmonary veins → left atrium → mitral valve → left ventricle

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4
Q

What is the pathway of blood flow from the left ventricle to the body?

A

Left ventricle → aortic valve → aorta → body

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5
Q

What is the function of the sinoatrial (SA) node?

A

Causes atria to contract, ejecting blood into ventricles

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6
Q

What role does the atrioventricular (AV) node play in the conduction system?

A

Delays signal to ventricles

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7
Q

What is the function of the common bundle of His?

A

Transmits signal to ventricles

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8
Q

What do the right and left bundle branches do?

A

Transmit signal to ventricles

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9
Q

What is the role of Purkinje fibres?

A

Transmit signal to ventricles

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10
Q

What causes the ventricles to contract?

A

Ventricular myocardium

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11
Q

What happens during ventricular contraction?

A

Ejects blood into aorta and pulmonary artery

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12
Q

What occurs during ventricular relaxation?

A

Allows blood to fill ventricles from atria

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13
Q

How do valves operate in the heart?

A

Open and close in response to pressure changes in the heart chamber

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14
Q

What does the P wave represent in an ECG?

A

Atrial depolarisation - atria contract

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15
Q

What does the QRS complex represent in an ECG?

A

Ventricular depolarisation - ventricles contract

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16
Q

What does the T wave represent in an ECG?

A

Ventricular repolarisation - ventricles relax

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17
Q

What is masked by the QRS complex in an ECG?

A

Atrial repolarisation

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18
Q

What effect does hypokalemia ([K+] decrease) have on myocardial excitability?

A

Increases myocardial excitability, with increased pacemaking and conducting tissues

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19
Q

What ECG change is associated with hypokalemia?

A

Depressed ST segment due to increased repolarisation time

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20
Q

What effect does hyperkalemia ([K+] increase) have on myocardial excitability?

A

Reduces myocardial excitability, with depression of both pacemaking and conducting tissues

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21
Q

What ECG changes are associated with hyperkalemia? (List 3)

A
  • Peaked T wave due to decreased repolarisation time
  • Widened QRS due to decreased conduction velocity
  • Prolonged PR interval due to decreased conduction velocity
  • Loss of P wave due to decreased conduction velocity
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22
Q

What does coronary artery disease (CAD) involve?

A

Narrowing of coronary arteries due to atherosclerosis

Atherosclerosis is the buildup of fats, cholesterol, and other substances in and on the artery walls.

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23
Q

What is myocardial infarction (MI)?

A

Heart attack due to prolonged ischemia and necrosis of heart muscle

Ischemia refers to an inadequate blood supply to an organ or part of the body.

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24
Q

What condition is referred to by cerebrovascular disease?

A

Stroke due to reduced blood flow to the brain

Stroke can result in lasting neurological damage, complications, and death.

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25
What does peripheral artery disease affect?
Narrowing of arteries in the legs and arms due to atherosclerosis ## Footnote This can lead to reduced blood flow, causing pain and mobility issues.
26
What are congenital heart defects?
Structural problems with the heart present at birth ## Footnote These defects can affect the heart's normal function.
27
What is deep vein thrombosis (DVT)?
Blood clot in a deep vein, usually in the legs ## Footnote DVT can lead to serious complications, including pulmonary embolism.
28
What occurs in a pulmonary embolism?
Blockage of a pulmonary artery by a blood clot that has traveled from the legs or other parts of the body ## Footnote This condition can be life-threatening and requires immediate medical attention.
29
What is heart failure?
Condition in which the heart cannot pump enough blood to meet the body’s need ## Footnote Heart failure can result from various heart conditions, including coronary artery disease.
30
What is the leading cause of death globally?
Cardiovascular disease (CVD) ## Footnote CVD encompasses a range of heart and blood vessel disorders.
31
How many deaths were attributed to CVD in 2021?
Approximately 20.5 million deaths ## Footnote This statistic is from the Global Burden of Disease Study 2021.
32
Where do approximately three-quarters of CVD deaths occur?
In low- and middle-income countries ## Footnote This highlights the disparity in health outcomes globally.
33
What are most causes of CVD considered to be?
Preventable and treatable ## Footnote This indicates the importance of lifestyle changes and medical interventions.
34
What are modifiable risk factors for CVD?
Factors that can be changed or controlled to reduce the risk of developing cardiovascular disease ## Footnote Examples include high blood pressure, smoking, and obesity.
35
What is necessary to reduce cardiovascular risk among people with hypertension, diabetes, and high blood lipids?
Drug treatment ## Footnote Effective management of these conditions can prevent heart attacks and strokes.
36
What are non-modifiable risk factors?
Factors that cannot be changed or controlled ## Footnote Examples include age, gender, and family history.
37
What does acute coronary syndrome (ACS) describe?
A range of conditions associated with sudden, reduced blood flow to the heart ## Footnote It is a critical condition that requires immediate medical attention.
38
What is unstable angina?
Chest pain or discomfort that occurs at rest or with minimal exertion ## Footnote Unstable angina is a sign of a heart attack risk.
39
What characterizes ST-elevation myocardial infarction (STEMI)?
ST-segment elevation on an ECG, indicating a complete blockage of a coronary artery ## Footnote STEMI is a critical type of heart attack requiring immediate intervention.
40
What is non-ST-elevation myocardial infarction (NSTEMI)?
A type of MI characterized by elevated cardiac biomarkers but no ST-segment elevation on an ECG ## Footnote NSTEMI indicates partial blockage of a coronary artery.
41
What does myocardial ischemia involve?
Reduced blood flow to the heart muscle, which can lead to chest pain or discomfort (angina) ## Footnote If untreated, it may progress to myocardial infarction.
42
What is the common term for Acute Myocardial Infarction?
Heart attack
43
What does ST elevation (STEMI) indicate?
Complete blockage of a coronary artery
44
What does ST depression (NSTEMI) indicate?
Partial blockage of a coronary artery
45
Name one method used to diagnose Acute Myocardial Infarction.
ECG changes
46
What are some cardiac biomarkers used in diagnosing AMI?
47
List two symptoms of Acute Myocardial Infarction.
* Chest pain * Shortness of breath
48
What imaging tests are used in the diagnosis of AMI?
* Echocardiogram * Coronary angiography
49
What may be the first sign of coronary artery disease (CAD)?
Acute Myocardial Infarction (AMI)
50
Describe chest pain associated with AMI.
Pressure, squeezing, fullness or pain in the centre or left side of the chest
51
What are common areas where pain or discomfort may occur during AMI?
* Arms * Back * Neck * Jaw * Stomach
52
What can trigger shortness of breath in AMI?
May occur with or without chest discomfort
53
What symptoms may occur due to reduced blood flow to the brain during AMI?
* Nausea * Vomiting * Lightheadedness
54
What causes cold sweat during AMI?
Activation of the sympathetic nervous system in response to stress or pain
55
Why do we assess cardiac function?
* Suspicion of damage * Diagnose acute coronary syndrome (ACS) * Monitor patients with known heart disease * Monitor effects of intervention * Screening for heart disease in high-risk individuals
56
Name a high-risk factor for heart disease.
* Family history of heart disease * Hypertension * Abnormal cholesterol levels * Arrhythmia
57
What are cardiac markers?
Substances released into the blood when the heart is damaged or stressed ## Footnote They should be used for diagnosis and monitoring of heart disease.
58
Are cardiac markers used for screening of heart disease?
No, they are not used for screening of heart disease ## Footnote They are primarily for diagnosis and monitoring.
59
What characteristics should cardiac markers have?
They should be: * Cost effective * Easy to measure * Specific to the heart * Sensitive to changes in heart function/damage
60
Define sensitivity in the context of cardiac markers.
Ability of a test to correctly identify those with the disease (true positive rate)
61
Define specificity in the context of cardiac markers.
Ability of a test to correctly identify those without the disease (true negative rate)
62
What is Creatine Kinase (CK)?
An enzyme found in heart, brain and skeletal muscle ## Footnote It is a historic biomarker.
63
What does Lactate Dehydrogenase (LDH) indicate?
An enzyme found in many tissues including heart, liver and skeletal muscle ## Footnote It is a historic biomarker.
64
What is Aspartate Aminotransferase (AST)?
An enzyme found in heart, liver and skeletal muscle ## Footnote It is a historic biomarker.
65
What is Myoglobin?
An oxygen-binding protein found in heart and skeletal muscle ## Footnote It is a historic biomarker.
66
What are the current cardiac biomarkers?
They include: * Troponin * B-type natriuretic peptide (BNP) * N-terminal pro-B-type natriuretic peptide (NT-proBNP)
67
What is Troponin?
A protein complex found in cardiac and skeletal muscle ## Footnote It includes Troponin I (cTnI) and Troponin T (cTnT), both specific to cardiac muscle.
68
What is Troponin I (cTnI)?
Troponin specific to cardiac muscle
69
What is Troponin T (cTnT)?
Troponin specific to cardiac muscle
70
What does B-type natriuretic peptide (BNP) indicate?
A non-AMI cardiac biomarker
71
What does N-terminal pro-B-type natriuretic peptide (NT-proBNP) indicate?
A non-AMI cardiac biomarker
72
What is Troponin?
A protein complex found in cardiac and skeletal muscle that regulates muscle contraction ## Footnote Troponin plays a crucial role in muscle contraction by controlling the interactions between actin and myosin.
73
What are the three subunits of Troponin?
* Troponin C (cTnC) * Troponin I (cTnI) * Troponin T (cTnT) ## Footnote Each subunit has a specific function in muscle contraction regulation.
74
What is the most reliable and widely used biomarker for diagnosing myocardial infarction (MI)?
Troponin ## Footnote Troponin levels are measured to assess cardiac injury following an MI.
75
How quickly is Troponin released into the bloodstream following myocardial injury?
Rapidly ## Footnote Troponin can be detected within 3-4 hours of MI onset.
76
What are the peak levels of Troponin after MI onset?
12-24 hours ## Footnote This timeline is critical for diagnosing and managing myocardial infarction.
77
When should Troponin be re-checked if the initial test is negative?
After 6-12 hours ## Footnote This is important for accurate diagnosis in suspected cases of MI.
78
Which Troponin is commonly measured for clinical practice?
cTnI Troponin I ## Footnote Multiple commercial assay vendors provide testing for cTnI.
79
What is the cut-off value for cTnI?
15 ng/L ## Footnote This value is used to determine the presence of myocardial injury.
80
Which Troponin is specific to Roche diagnostics?
cTnT Troponin T ## Footnote cTnT is used in conjunction with cTnI for diagnosing MI.
81
What is the cut-off value for cTnT?
12 ng/L ## Footnote This value helps in assessing myocardial damage.
82
What are two limitations of Troponin testing?
* False positives due to renal failure * False positives due to myocarditis ## Footnote These conditions can lead to elevated Troponin levels without actual myocardial injury.
83
What is Macrotroponin?
Large troponin molecules that can interfere with immunoassays ## Footnote Macrotroponin can result in falsely elevated troponin levels and does not indicate myocardial injury.
84
What causes negative interference on cTnT?
Haemolysis ## Footnote Haemolysis releases proteases from red blood cells, affecting Troponin T levels.
85
True or False: cTnT is more prone to false positives than cTnI.
True ## Footnote This is an important consideration when interpreting test results.
86
Fill in the blank: Both cTnI and cTnT are ______ for diagnosing myocardial infarction.
specific to cardiac muscle ## Footnote Both assays are essential for accurate diagnosis of MI.
87
How long does TnT persist in the blood compared to TnI?
TnT persists longer ## Footnote This characteristic is useful for late presentations of myocardial infarction.

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