cvd definitions

Question 1

after load

Answer 1

o Afterload is the amount of tension developed by the ventricles during contraction to open the semilunar valves

o High afterload may lead to myocardial damage and heart failure

Question 2

preload

Answer 2

o Preload is the degree of stretching of myocardial fibers during ventricular diastole
o Preload is significant because it determines the ability of the muscle fibers to shorten and develop tension
o The higher the preload, the higher the tension developed and the greater the stroke volume

Question 3

inotropy

Answer 3

o Inotrope: an agent that alters the force of muscular contractions
o Negative inotropic agents weaken the force of contraction
o Positive inotropic agents increase the strength of contraction
o Ventricular hypertrophy increases inotropic state
o Myocardial infarction decreases inotropic condition
o Many inotropes alter preload and afterload

Question 4

chronotropy

Answer 4

o Chronotropic effects alter the rate of heart contractions
o Negative chronotropic agents decrease heart rate
o Positive chronotropic agents increase heart rate
o Negative chronotropes include beta blockers, acetylcholine, digoxin, verapamil
o Positive chronotropes include adrenergic agonists, atropine, dopamine, theophylline