Heart Failure - Pathophysiology & Management

Question 1

What is HF caused by?

Answer 1

It is caused by structural/functional abnormalities of the heart.
Imbalance of pump function = metabolic needs of the body are not met due to poor blood circulation.

Question 2

What are the 3 categories of HF?

Answer 2

They are based on LVEF (left ventricular ejection fraction)

1. LVEF <50%
2. LVEF 40-49%
3. LVEF <40%

Question 3

What is the definition of preload?

Answer 3

It is the vol. of blood that must be pumped within each beat.
High preload = high stroke vol.
Low preload = low stroke vol. + trapped blood, causing chamber enlargements

Question 4

What is the definition of afterload?

Answer 4

It is the pressure to overcome to pump blood into the arterial system.
It is also dependent on the systemic vascular resistance.
High afterload = cardiac muscles work harder to overcome vascular resistance + chamber enlargement + low cardiac output

Question 5

What conditions can cause HF?

Answer 5

1. Diabetes
2. Infection
3. Chronic alcohol intake
4. CVD

Question 6

What causes myocardial injury?

Answer 6

Decreased renal perfusion & baroreceptor stimulation.

Question 7

How are the symptoms of HF activated?

Answer 7

Via RAAS & SNS activation, which increases HR & myocardial toxicity.
This also worsens LVEF
Symptoms include: cyanosis (blue skin), respiratory distress, pulmonary congestion.

Question 8

What are some examples of the pharmacotherapy used in HF?

Answer 8

1. Diuretics
2. Digoxin
3. Neurohormonal antagonists (ACEi, ARBs)
4. B-blockers
5. Ivabradine
6. Vasodilators
7. Novel agents
8. Inotropics
9. Antiglycemic agents

Question 9

What is the dosing used for ACEi in the treatment of HF, e.g. ramipril?

Answer 9

Start at a low dose & then x2 at weekly intervals.
ACEi should be stopped if K+/Cr levels are high.
Consider ARB’s (angiotensin receptor blockers, e.g. sartan) if ACEi causes coughing

Question 10

What is an example of an MRA drug?

Answer 10

MRA: Mineralocorticoid receptor antagonists

- E.G. Spironolactone

Question 11

What is the mechanism of ARNI drugs?

Answer 11

ARNI: angiotensin receptor/neprilysin inhibitor

• It inhibits the breakdown of ANP & increases urine production + vasodilation
• Given to patients with LVEF <40%

Question 12

When is hydralazine given?

Answer 12

It is 1st line if ACEi/ARB not given.

It is also 2nd line for black people.

Question 13

What is the mode of action of ivabradine?

Answer 13

It blocks If channels & reduced f current, which leads to decreased depolarisation of SA node.

Question 14

When is digoxin used in HF?

Answer 14

It is used in severe HF.

Not commonly given as it interacts with b-blockers & causes hypokalaemia.

Question 15

How do SGLT2 drugs decrease cardiac preload/afterload?

Answer 15

SGLT2: sodium glucose co-transporter 2 inhibitors, e.g. dapagliflozin

• It decreases glucose/Na+ reabsorption in kidneys, which increases urinary glucose/Na+
• This in turn decreases cardiac preload/afterload.