Chronic Heart Disease

Question 1

Define contractility

Answer 1

The concept that if a muscle is stretched it will contract with greater force.

Question 2

Define preload.

Answer 2

The volume of blood in the ventricles before contraction.

Also known as “end diastolic volume”.

Question 3

Cardiac output = ? (equation)

Answer 3

Heart rate (bpm) x Stroke Volume (vol of blood leaving the heart per beat)

Question 4

What is heart failure?

Answer 4

The inability to maintain cardiac output.

Question 5

Outline the process of heart failure.

Think: CO = HRxSV, preload, contractility etc.

Answer 5

Muscle is damaged so can’t contract as well, SV decreases and HR increases to maintain CO.
This makes diastole shorter so the preload increases, leading to stretching of the ventricular walls.
The LV has to work harder and becomes hypertrophic.
Muscle grows inwards into the chambers so the SV decreases.
Hormones cause the LV to become dilated and floppy so contractility decreases (and th4 SV too).

Question 6

What happens when kidney perfusion decreases?

Answer 6

Renin release, which leads to the conversion of angiotensin 1 -> 2.
This leads to high blood pressure.

Question 7

What does Angiotensin II do?

Answer 7

Vasoconstricts.

Activates aldosterone which acts on the Na/K pump in the kidney tubules, increasing Na uptake into the plasma.
Water likes to follow sodium so urine output decreases and plasma volume increases.
– water retention.

Question 8

How do you get peripheral oedema in heart failure?

Answer 8

Decreased kidney perfusion leads to increased angiotensin II and therefore increased blood pressure.
Increased plasma volume means the preload is increased and that hydrostatic pressures are high, leading to peripheral oedema.

Question 9

How can valvular problems lead to heart failure?

Answer 9

Stenosis - increases afterload

Regurge - increases preload

Question 10

What are the common causes of broad complex arrythmias?

Answer 10

Deranged potassium levels
MI
Heart failure

Question 11

Which arrythmias can you shock?

Answer 11

broad complex ones only

Question 12

What does monomorphic VT look like and what is it due to?

Answer 12

ECG: uniform 120-190bpm

Due to re-entrant circuits in the ventricles
-scarring: previous MI

Question 13

What does polymorphic VT look like on ECG?

Answer 13

Varying height of QRSs

Irregular

Question 14

What are the causes of polymorphic VT?

Answer 14

metabolic changes
drugs
ischaemia

• due to abnormal ventricular triggering

Question 15

How do you treat VT?

Answer 15

resus - cardiac arrest!
amiodarone
underlying cause

Question 16

Define the CHADS2 score? What’s it used for?

Answer 16

Stroke risk.

Congestive HF
Hypertension
Age >75
Diabetes
Stroke or TIA

Question 17

What does AF look like on ECG?

Answer 17

Chaotic baseline - no P-waves

Irregularly irregular

Question 18

Causes of AF?

Answer 18

Cardiac: ischaemia
valve problems
hypertension

Pulmonary Embolism
Hyperthyroid
Metabolic
Alcohol
Infection

Question 19

Atrial Flutter: pathophysiology?

Answer 19

Micro re-entry circuit clockwise inside right atrium
300bpm
BUT: ventricles only get a specific fraction:
-150bpm = 2:1
-300bpm = 3:1

Question 20

Atrial Flutter: ECG changes?

Answer 20

regular narrow QRSs
Saw tooth (due to atrial depolarisation)