Cardiology Flashcards

1
Q

What does the P wave of an ECG represent?

A

atrial depolarisation

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2
Q

What does the QRS complex of an ECG represent?

A

ventricular depolarisation

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3
Q

What does the ST segment of an ECG represent?

A

Interval between ventricular depolarisation and repolarisation

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4
Q

Define systole

A

Contraction phase

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5
Q

Define diastole

A

Filling phase

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6
Q

What is normal systemic systolic and diastolic BP respectively?

A

120 mmHg and 80 mmHg

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7
Q

What is normal pulmonary systolic and diastolic BP respectively?

A

28 mmHg and 10 mmHg

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8
Q

Cardiac output (CO) =

A

Stroke volume (SV) x Heart rate (HR)

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9
Q

What is normal ejection fraction (LVEF)?

A

55-70% of SV

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10
Q

What 3 things can influence ejection fraction?

A

Ventricular pre-load
Myocardial contractility
Ventricular afterload

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11
Q

What is ‘pre-load’?

A

Volume of blood in the ventricles at the beginning of systole

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12
Q

What is the main contributor to pre-load? What theory is this based on?

A

Venous return

Starling’s law

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13
Q

What is Starling’s law?

A

The greater the venous return > the greater the filling (pre-load) > greater stretch on the myocardium > stronger ventricular contraction

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14
Q

What factors influence pre-load?

A
Posture
Blood volume
Sympathetic tone
Intrathoracic pressure 
Intrapericardial pressure
Exercise
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15
Q

What is myocardial contractility?

A

The force generated by the heart in ejecting blood from the ventricles

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16
Q

What factors influence contractility?

A
Pre-load
Increased ANS activity 
Hormones (eg. adrenaline)
Stress
Ischaemia
Damaged/diseased myocardium
17
Q

What is ‘after load’? Dictated by what?

A

Tension in the myocardium during contraction
What the blood has to be contracted against
Dictated by systemic vascular resistance (SVR)

18
Q

What factors affect SVR?

A

Vessel length
Vessel radius
Viscosity of blood

19
Q

What is laminar flow?

A

Blood flows faster in centre of vessel and slower at the edges

20
Q

Blood pressure (BP) =

A

Cardiac output (CO) x Systemic vascular resistance (SVR)

21
Q

Why does post-exercise hypotension occur?

A

Reduced SV and therefore reduced CO > Leads to reduced BP

Following exercise, vessels remain dilated > leads to reduced BP

22
Q

What is the effect of Nitric Oxide in vessel walls?

A

Relaxes smooth muscle