Pathophysiology of Heart Disease

Question 1

Progression of heart failure classification

Answer 1

Class I - no symptomatic limitation of physical activity
Class II - slight limitation of physical activity, no symptoms at rest
Class III - marked limitation of physical activity, less than ordinary physical activity results in symptoms, no symptoms at rest
Class IV - inability to carry out any physical activity without symptoms, may have symptoms at rest

Question 2

Physiology of the heart: cardiac output, stroke volume, LV end systolic volume, LV end diastolic volume, ejection fraction, weights

Answer 2

Cardiac output - 5 litres/min
Stroke volume - 75 ml/beat
LV end systolic volume - 75 ml
LV end diastolic volume - 150 ml
Ejection fraction - 50% plus
Weight - 330g

Question 3

Left ventricular systolic dysfunction

Answer 3

• Increase LV capacity
• Reduced LV cadiac output
• Thinning of myocardial wall
• Mitral valve incompetence
• Neurohormonal activation
• Cardiac arrythmias

Question 4

Concentric and eccentric hypertrophy

Answer 4

Concentric occurs in response to pressure overload, cardiomyocytes grow in width and results in an increase in wall thickness.
Eccentric occurs in response to volume overload, results in cardiomyocyte elongation.

Question 5

What are some long term deleterious effects on the sympathetic nervous system in heart failure?

Answer 5

• Beta adrenergic receptors are down regulated
• Noradrenaline induces cardiac hypertrophy / myocyte apoptosis and necrosis via a-receptors, induce up regulation of the RAAS
• Reduction in heart rate variability