Investigation and risk factors for ischaemic heart disease and myocardial infarction (1)

Question 1

What can asses cardiovascular risk?

Answer 1

QRISK3 assessment tool

Question 2

What was used to be used as cardiac markers and why not anymore?

Answer 2

Used to use CK-MB, myoglobin, AST (aspartate transaminase) and LDH (lactate dehydrogenase) but these are not specific

Question 3

What does troponin marker tell us?

Answer 3

damage to a cardiac muscle cell
cant diagnose a myocardial infarction
Specific to heart not ischemia

Question 4

What marker is used for damage to a cardiac muscle cell

Answer 4

Troponin

Question 5

What is the diagnostic criteria for MI?

Answer 5

Detection of a rise and/or fall in cardiac biomarker values (preferably troponin) with at least one value above the 99th percentile of the reference limit and at least one of the following:

• Symptoms of ischaemia
• New or presumed new significant ST changes or new LBBB
• Development of pathological Q waves on the ECG
• Imaging evidence of new loss of viable myocardium
• Identification of intracoronary thrombus by angiography

Question 6

What diseases can cause troponin to be raised?

Answer 6

MI

Angina

Question 7

What is the specificity and sensitivity of Troponin marker

Answer 7

More sensitive but less specific — more false positives

Question 8

What is happens to the heart if there is hyperkalemia?

Answer 8

Raised potassium increases cardiac excitation
- Increases risk of cardiac arrhythmias

As hyperkalaemia increases, heart block may occur
ECG signs — tented T waves hyper acute t wave, reduced P wave amplitude

Question 9

Drugs: How do you lower potassium levels in the blood? What is used to protect the cardiac muscle?

Answer 9

Salbutamol
Insulin
Calcium gluconate

Question 10

What are causes of hyperkalaemia?

Answer 10

Pre-sampling: incorrect order of sampling (SST tube should be filled
before the EDTA tube)
Post-sampling — haemolysis of blood sample, unseparated sample
Acute kidney injury, chronic kidney disease
Drugs-Potassium-sparing diuretics, ACE-inhibitors, ARBs, NSAIDs

Mineralocorticoid deficiency (Addison disease)

Question 11

How do ACE inhibitors increase potassium levels?

Answer 11

Aldosterone is used to work Na+/ K+ pump excreting K+ in the tubules of the kidney
Aldosterone is made from Angiotensinogen catalysed to Angiotensin I by Renin then Angiotensin I to Angiotensin II by ACE then Angiotensin II acts on the adrenal cortex, specifically the zona glomerulosa here, it stimulates the release of aldosterone.
ACE inhibitor inhibits ACE
Pump no longer works

Question 12

What is ACE

Answer 12

Angiotensin converting enzyme

Question 13

Why do you need the SST tube to be filled

before the EDTA tube?

Answer 13

EDTA tube has anticoagulant Potassium- EDTA complex
When taking blood and putting in tubes can get back flow which can carry to next tube. Normally fine but EDTA pottassium breaks down for things like magnesium Higher reactivity now wit looks like the patient has high pottassium

Question 14

What happens if sample is left overnight>

Answer 14

Pottassium levels inaccurate

Question 15

What is happens to the heart if there is hypokalemia?

Answer 15

Increases the gradient across the cardiac cell membrane — increases the action potential and therefore reducing cardiac excitability
May cause arrhythmias such as atrial fibrillation
ECG changes: reduced T waves, ST depression, prolonged PR interval

Question 16

What are causes of hypokalaemia?

Answer 16

• Gastrointestinal loss — diarrhoea and vomiting
• Endocrine conditions: increased mineralocorticoid activity (Conn’s syndrome, Cushing syndrome)
• Diuretics (non-potassium sparing)
• Insulin treatment with no potassium supplementation

Question 17

What are causes of secondary hypertension?

Answer 17

Chronic kidney disease
Renovascular hypertension (renal artery stenosis)
Phaeochromocytoma
Primary hyperaldosteronism (Conn's syndrome)
Cushing syndrome
Acromegaly
Coarctation of the aorta
Pregnancy

Question 18

What laboratory investigation of hypertension helps to diagnose renal disease?

Answer 18

Plasma creatinine

Urinalysis for protein

Question 19

What laboratory investigation of hypertension helps to diagnose Mineralocorticoid excess ?

Answer 19

Plasma potassium

Question 20

What laboratory investigation of hypertension helps to diagnose Conn’s syndrome

Answer 20

Plasma renin / aldosterone

Question 21

What laboratory investigation of hypertension helps to diagnose Cushing syndrome

Answer 21

Dexamethasone suppression test

Question 22

What laboratory investigation of hypertension helps to diagnose Phaeochromocytoma

Answer 22

Urinary catecholamines

Question 23

How does chronic kidney disease cause secondary hypertension

Answer 23

Causes fluid retention causes SH

Question 24

How does Conns syndrome cause secondary hypertension

Answer 24

Excess aldosterone causes sodium retention causes SH

Question 25

How does Cushing syndrome cause secondary hypertension

Answer 25

Excess aldosterone causes sodium retention causes SH

Question 26

How does Phaeochromocytoma cause secondary hypertension

Answer 26

Stimulation of cardiac Beta 1 adrenoreceptors