Cardiac Output

What AFFECTS preload?

- Total blood volume and volume distribution - Cardiac compliance - Myocardial contractility - Increase in afterload or ventricular impedence

Afterload is AFFECTED by what?

- Vasodilation/vasoconstriction - Valvular impedence - Atherosclerosis (turbulant vs laminar flow) - Blood volume and viscosity

What 3 factors INFLUENCE cardiac output?

1. Preload (Intravascular fluid volume) 2. Afterload (Vascular resistance) 3. Contractility of the heart

What is end systolic volume?

Amount of blood in the ventricles at the end of ventricular systole

What is the formula for cardiac output?

CO = HR x Stroke volume

What is cardiac output AFFECTED by?

Cardiac function and fluid status

The strength of the hearts contraction is known as what?

Contractility

Preload is INFLUENCED by what?

It is affected by the blood returning to the heart via pulmonary or systemic veins

What is myocardial tension caused by stretching before contraction?

Preload

Preload, Afterload and contractility affect what?

Stroke volume

What is end diastolic volume?

The amount of blood in the ventricle at the end of ventricular diastole - After the atrial kick

What is cardiac output?

The amount of blood pumped by the heart each minute (L/min)

What is stoke volume?

The amount of blood pumped with each heartbeat

What is afterload?

The resistance against which the heart must pump to get blood into the arteries

You need adequate cardiac output for what?

To perfuse organs and tissues

What is the average stroke volume in an adult?

~ 70mls