Week 2 Cardiac Foundations Flashcards
How is Cardiac output calculated?
Stroke volume X HR
What is Cardiac output?
The amount of blood the heart pumps in one minute
What is the normal range for cardiac output?
4-8L/min
What is stroke volume?
the volume of blood pumped from one ventricle of the heart with each beat
What is the average stroke volume in most adults?
70ml
What is stroke volume influenced by?
the amount of blood that returns to the right atrium from venous circulation and pulmonary veins into left ventricle
A higher stroke volume increases ___
Workload
How does tachycardia affect stroke volume?
It decreases stroke volume due to decreased filling time
How does tachycardia affect workload?
it increases it
How does tachycardia affect heart O2 demand?
It increases it
The goal of medication therapy for cardiac patients in to _____
decrease the workload of the heart
Cardiac medications decrease the workload of the hear by manipulating ______. (5 things)
SV. HR, preload, afterload, and contractility
What is preload?
The filling pressure of the right ventricle and the left ventricle.
Preload is influenced by____
Blood volume and the amount of venous return
Higher venous return results in ____ SV
Higher
Fluid volume deficit results in a ___ SV
Lower
____ measures preload
central venous pressure
What is the normal value for CVP?
2-6mm/Hg
According to starlings law, in a healthy heart, increasing preload will increase ____ which will increase ___
SV, contraction strength
Chronic Heart failure will lead to ___ of the ventricles
Over-stretching
Drugs that cause venous dilation will ___ preload
Decrease
Diuretics that eliminate excess fluids will ____ preload
Decrease
Starlings Law of the heart states that ___
If preload is increased, a greater quantity of blood that is ejected during systole due to increased stretch of the myocardium and larger amount of blood present
The greatest force of contraction is when the muscle fibers are stretched ___ times their normal length
2.5
