Assessing cardiac function

Question 1

Functions of the heart

Answer 1

• Appropriate rhythm
• Valve competence
• Chamber size
• Myocardial blood supply

Question 2

How to calculate stroke volume

Answer 2

Difference between LVEDV and LVESV

Question 3

How to calculate cardiac output

Answer 3

CO = SV x HR

Question 4

What is the ejection fraction?

Answer 4

Proportion of LVEDV that is ejected

Question 5

How to calculate BP

Answer 5

BP = CO x SVR

Question 6

Symptoms of heart failure

Answer 6

• Coughing
• Tiredness
• Shortness of breath
• Pulmonary oedema
• Pleural effusion
• Abdominal swelling
• Swelling in ankles/legs

Question 7

Most common cause of HF

Answer 7

Coronary artery disease (ischaemic heart disease)

Question 8

ECG of AF

Answer 8

No P waves, QRS normal but irregularly irregular

Question 9

Holter ECG

Answer 9

• Ambulatory monitoring
• Palpitations, dizziness, blackouts
• Frequently recurring
• Automatic detection and patient triggered events

Question 10

Implantable loop recorders

Answer 10

• Sits in chest wall to continually monitor heart function

- Re-records 20 minutes and stores when abnormal

Question 11

STEMI ECG

Answer 11

St elevation and emergence of Q wave

Question 12

Exercise testing

Answer 12

• Dependent on fitness of pt
• See if causal relationship between sx and ischaemia
• Not used for diagnosis/exclusion alone
• To stress heart, increase MET
• MET = energy cost of physical activity
• Average MET is 3.5ml of oxygen per kilo per minute

Question 13

Pharmacological test for ischaemia

Answer 13

• Dobutamine (B agonist) - raises BP and HR, increases cardiac activity, increases demand of heart muscle for blood , induces ischaemia
• Infusion vasodilator - relative ischaemia, where vasodilation is not possible because of stenoses
• Radioactive nucleotide injected and emits gamma waves which can be detected by camera

Question 14

Thallium myocardial perfusion scan

Answer 14

• Useful in pts with intermediate probability of coronary disease
• Useful if mobility limits treadmill testing or if resting ECG is abnormal
• Thallium taken up by myocardium in proportion to blood flow not by scar tissue
• Detected by gamma camera
• Images taken under stress or at rest

Question 15

Transthoracic echocardiography

Answer 15

• Chamber size
• Muscle contractility - stressed by exercise or pharmacologically
• Calculate EF
• Valve function - stenosis or regurgitation, doppler

Question 16

In what direction is an object moving if it appears blue?

Answer 16

Away from probe

Question 17

LV internal dimension end diastolic

Answer 17

3.7 to 5.6

Question 18

LV internal dimension end systolic

Answer 18

2.5 to 4.1

Question 19

Transoesophageal echocardiography

Answer 19

• When TTE poor view
• When clear view of valves is needed (infective endocarditis)
• When clear view of inter-atrial septum and atrial appendages needed (cryptogenic stroke)

Question 20

Bubble echo

Answer 20

• Detects shunts
• Intensifying TR signal when you have difficulty estimating RV systolic pressire
• Delineating right heart borders and masses (RV wall thickness)
• Improving imaging of pulmonary trunk and arteries especially when looking for thrombi

Question 21

Stress echocardiography

Answer 21

• Chest pain investigation
• See HR during exercise
• Screening test before starting exercise programme
• Assess symptom and BP when pt has heart valve disease

Question 22

Cardiac CT

Answer 22

• Structure of herat and vessels
• 3D reconstruction - coronary artery mapping
• Not best for looking at myocardium

Question 23

Cardiac MRI

Answer 23

• Structure and muscle function
• Good for detailed structure
• No radiation
• Not as good as CT for observing calcification