Pathophysiology of Heart Failure

Question 1

What is afterload?

Answer 1

The force the contracting heart must generate to eject blood from the heart

Question 2

What are the patients symptoms in Class I HF as defined by th New York Heart Association?

Answer 2

No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea

Question 3

What is ascites?

Answer 3

An abnormal buildup of fluid in the abdomen

Question 4

What can right sided heart failure cause?

Answer 4

• Conjestion of peripheral tissues
• Oedema and ascites
• GI tract conjestion
  anorexia, GI distress, weight loss
• Liver conjestion
  Impaired liver function

Question 5

What can left sided heart failure cause?

Answer 5

• Decreased CO
• Activity intolerence, signs of decreased tissue perfusion
• Cyanosis and signs of hypoxia
• Pulmonary conjestion
• Cough with frothy sputum
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Right heart failure

Question 6

What is class II HF as defined by the NYHA?

Answer 6

Slight limitation of physical activity. Comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnoea

Question 7

What is class III HF as defined by the NYHA?

Answer 7

Marked limitation of physical activity. Comfortable at rest. Less than ordinary activity causes fatigue, palpitations, or dyspnea

Question 8

What is class IV HF as defined by the NYHA?

Answer 8

Unable to carry on any physical activity without discomfort. Symptoms of HF at rest. If any physical activity is undertaken, discomfort increases.

Question 9

What is preload?

Answer 9

Determined by venous return; EDV.

Question 10

What are the main components of afterload?

Answer 10

Vascular resistance; ventricular wall tension

Question 11

What is the normal ventricular ejection fraction?

Answer 11

~50-60%

Question 12

What is systolic ventricular dysfunction?

Answer 12

Impaired cardiac contractility therefore decreased ejection fraction (<40%)

Question 13

What is diastolic ventricular dysfunction?

Answer 13

• Normal ejection fraction but impaired diastolic ventricular relaxation and decreased filling
• Therefore decrease in SV and CO

Question 14

Systolic dysfunction commonly results from conditions that affect what?

Answer 14

• Contractility
• Volume overload
• Pressure overload

Question 15

Diastolic dysfunction commonly results from what?

Answer 15

• Impedance of ventricular expansion
• Increased wall thickness
• Delayed diastolic relaxation
• Increased HR

Question 16

What does systolic dysfunction result in?

Answer 16

• Increased EDV (preload)
• Ventricular dilation
• Increased ventricular wall tension

Question 17

What is more common diastolic or systolic dysfunction?

Answer 17

Systolic dysfunction

Question 18

What are the causes of right ventricular dysfunction?

Answer 18

• Conditions impeding flow into the lungs
• Pumping ability of right ventricle
• Left ventricular failure
• Congenital heart defects

Question 19

What are the causes of left ventricular dysfunction?

Answer 19

• Hypertension (increased TPR)
• Acute MI
• Aortic or mitral valve stenosis or regurgitation
• Increase in pulmonary pressure can lead to right ventricular failure

Question 20

Are the body’s intrinsic mechansisms good for dealing with HF?

Answer 20

• In they early stages they are good as the compensatory mechanisms maintain cardiac output.
• Longer-term, they contribute to the worsening of the condition

Question 21

What receptors are desensitised by sympathetic activity?

Answer 21

Beta but not alpha receptors

Question 22

How does increased sympathetic activity affect the heart long term?

Answer 22

• Tachycardia, vasoconstriction, decreased perfusion of tissues, cardiac arrhythmias, renin release
• Increased workload of the heart which leads to ischaemia and damage to myocytes which decreases contractility
• Dessensitisation of B1 receptors

Question 23

What are the strategies for treating HF?

Answer 23

• Increasing cardiac contractility
• Decreasing preload and/or afterload to decrease cardiac work demand
  By relaxing smooth muscle
  By reducing blood volume
• Inhibit the RAAS
• Prevent inappropriate increase in HR

Question 24

What are the problems with the RAAS in treating HF?

Answer 24

• Decreased renal blood flow stimulates release of renin
• Renin release therefore increases angiotensin II formation (vasoconstrictor, plus stimulates aldosterone release)
• Sodium and water reabsorption is increased both directly (decreased flow rate through the kidney) and indirectly (via aldosterone)