Cardiac Physiology

Question 1

Valve anatomy and their locations

Answer 1

Only a small pressure gradient needed to open healthy valves

Aortic - R 2ICS
Pulmonary - L 2ICS
Tricuspid - L 5ICS
Mitral - L 5ICS MCL

Question 2

Cardiac cycle and how it relates to the ECG trace

Answer 2

P wave

• Passive LA filling
• LA > LV => mitral opens
• LA contracts

QRS complex

• LV contraction => mitral closes
• isovolumic contraction
• LV > A => aortic opens
• ventricular ejection

T wave

• end systolic pressure falls
• A > LV => aortic closes
• isovolumic relaxation
• LA > LV => mitral opens

Question 3

Ischemia definition

4 factors that determine size of infarct

Answer 3

Inadequate blood flow to meet demands of tissue

Size of area at risk
Levels of collateral flow
-increased ischemia => increased collateral formation
Duration of ischemia
Rate of cell death

Question 4

How do cells die in infarct

Answer 4

Hypoxia => anaerobic glycolysis, glycogen use
-glycogen runs out at 15mins => cells tear themselves apart => TnT released into

Ischemia and necrosis from subendocardium => spreads to epicardial region => transmural infarct

Question 5

3 primary causes of heart failure

Answer 5

Pressure overload => HTN, aortic stenosis
Volume overload => aortic/mitral regurgitation
Contractile issue => IHD, myocardial disease, cardiomyopathies

Question 6

Pathophysiology of heart failure

-management

Answer 6

Increased radius of heart => increased wall stress needed to produce same pressure

Hypertrophic remodelling to lower wall stress and radius

Abnormal hypertrophy

• inadequate angiogenesis
• more stiff

Neurohormonal response is maladaptive => drug targets
-ACEi, Bb, spironolactone