CVD diagnostic techniques

Question 1

Tests/methods used to screen for cardiovascular disease?

Answer 1

• Electrocardiography (ECG)
• Exercise tolerance test (cardiac stress test)
• Chest X-ray/ coronary angiography
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Blood tests

Question 2

What does an ECG measure?

Answer 2

Measures the electrical activity of the heart to indicate the rhythm of the heart’s beat
- PQRST

Question 3

What does P of PQRST mean?

Answer 3

• P wave: represents atrial depolarisation - the defecation is small as there is a minimal amount of muscle in the atrium

Question 4

What does Q mean in PQRST?

Answer 4

• Q wave: represents depolarisation at the bundle of His, this also has a minimal amount of muscle

Question 5

What does R represent in PQRST?

Answer 5

• R wave: this involves a lot of muscle and therefore the deflection is large. The wave represents the main spread of depolarisation from the inside out and through the base of ventricles

Question 6

What does S represent in PQRST?

Answer 6

• S wave: shows the following depolarisation of the rest of the ventricles (upwards from the base of the ventricles)

Question 7

What does T represent in PQRST?

Answer 7

• T wave: repolarisation is shown of the myocardium after systole is complete. You will notice a soft curved deflection as this process is slow

Question 8

Reasons for performing an ECG?

Answer 8

• suspected heart attack
• suspected pulmonary embolism
• a third heart sound, a fourth heart sound, a cardiac murmer or other findings to suggest structural heart disease
• percieved cardiac dysrythmias
• fainting or collapse
• seizures
• monitoring the effects of a heart medication
• assessing severity of electrolyte abnormalities, such as hyperkalaemia

Question 9

What is the exercise tolerance test?

Answer 9

• as some conditions such as angina and arrhythmias are bought on during exercise it is ideal to do an exercise tolerance test to mimic these conditions
• can be performed using an apparatus such as a treadmil or exercise bike
• the walking speed and incline is increased at intervals on the treadmil/the resistance on pedals are increased at intervals on the bike
• the patient’s ECG and blood pressure will be monitored throughout, and they will be monitored after they have completed the exercise
• the results will be analysed to see how the patient’s heart responds to exercise

Question 10

What are X-rays and coronary angiograms used for?

Answer 10

• chest x-rays are useful for detecting cardiac events which affect the structure of the heart or cause build up of fluid around the heart or lungs
• a coronary angiogram is a specific type od x-ray used to analyse the coronary arteies and identify any blockages
• some conditions that can be detected using these techniques include:
  
  • coronary heart disease
  • heart attacks
  • angina
  • congenital heart disease
  • cardiomyopathy

Question 11

What is a CT scan?

Answer 11

• CT scans are useful for showing what is happening in the heart without the need for cutting into the skin
• this imagine technique makes use of computer processed-combinations of many x-ray images taken from different angles to product cross-sectional (tomographic) images of specific areas of a scanned object, allowing the use to see the inside of the object without cutting into it
• a dye is usually administered (orally, parenterally or rectally) before the CT scan to improve the contrast of the image

Question 12

What is a Magnetic resonance imaging (MRI)?

Answer 12

• MRI scans use strong magnetic fields and radio waves to produce detailed images of the inside of the body
• an MRI can be used to examine almost any part of the body
• They are unsuitable for some patient groups, such as pregnant women and those with pacemakers
• key difference between MRI and CT scans - MRIs do no use radiotion (x-rays)

Question 13

What are radionuclide tests?

Answer 13

• myocardial perfusion scam
• the myocardial perfusion test checks blood supply to the heart, both under stress and at rest
• an injection containing a minimal amount of isotope is used to allow to check for the pumping action of the heart and check the blood flow

Question 14

What markers are there to look out for in blood tests?

Answer 14

• troponin
• creatinine kinase (CK)
• c-reactive protein (CRP)
• myoglobin
• erythrocyte sedimentation rate (ESR)
• b-type natriuretic peptide (BNP)
• cholesterol (Tc, LDL, HDL)

Question 15

Biomarkers in myocardial infarction ?

Answer 15

• troponin - only present when myocardial necrosis has occurred
• CK - raised due to damage to the heart muscle
• myoglobin - usually elevated within one hour of an MI
• CRP - inflammatory marker which is elevated in an MI
• ESR - indicator of inflammation in the body

Question 16

What is endocarditis and how is it diagnosed?

Answer 16

• rare but potentially fatal infection of the inner lining of the heart, most commonly caused by bacteria entering the blood and travelling to the heart
• symptoms: high temp, night sweats, headaches, SOB, cough, heartr murmur, painful red lumps or spots on hands and feet
• diagnosis - ECG to check for bacteria and damaged/infected heart tissue and CT scan for identifying abscesses in the body

Question 17

Endocarditis biomarkers?

Answer 17

• blood cultures to identify the bacteria or fungi causing the infection
• ESR and CRP - elevated in approx 90% of patients with endocarditis
• FBC

Question 18

Biomarkers in clotting disease?

Answer 18

• The d-dimer test is a specific test used for detecting clotting problems
• It can be used to identify:
  
  • deep vein thrombosis
  • pulmonary embolism
  • other forms of embolism
• the test measures a small protein fragment which is present in the blood after a blood clot degrades, It indicates significant clot formation and breakdown, but doesn’t specify the location of the clot
• other reasons for elevated results - recent surgery/trauma, infection, liver or kidney disease, pregnancy and cancers

Question 19

Biomarkers in coronary heart disease (CHD)?

Answer 19

• CHD describes what happens when the heart’s blood supply is blocked or interrupted by a build up of fatty substances in the coronary arteries
• LDL
• HDL
• Tgs
• CRP
• fibrinogen - clotting factor that is raised in CHD
• lipoprotein (a) - raised in CHD
• BNP - raised in any condition where the heart does not pump the way it should do. Also raised in all types of heart failure