Ventricular Function

Front 1

Define preload

Back 1

Degree of stretch of myocardial fibers prior to contraction

Front 2

Where is the is the "preload point" on the ventricular pressure volume loop?

Back 2

Ventricular End Diastolic Volume (lower right corner)

Front 3

The ______ valve closes at the end of diastole

Back 3

Mitral

Front 4

An increase in preload ______________ ventricular end diastolic volume (VEDV)

Back 4

increases

Front 5

Does an increase in preload increase contractillity?

Back 5

Usually as long as Lmax is not exceeded.

Both force and velocity of contraction are increased.

Front 6

Does an increase in preload change ventricular end systolic volume?

Back 6

No - more blood is ejected from heart, so ventricular end systolic volume remains the same.

Front 7

Define contractility.

Back 7

Index of the force (dP/dt) and extent of ventricular contraction.

Front 8

A change in contractility is mediated by ____________

Back 8

The chemical environment of a cardiac cell

Front 9

An increase in contractility will lead to an (increase/decrease) in emptying the ventricular chamber.

Back 9

Increase

Front 10

An an increase in contractility will lead to an (increase/decrease) in ventricular end systolic volume (VESV)

Back 10

Increase. VESV is shifted to the right on the ventricular pressure-volume loop.

Front 11

Does preload increase with contractility?

Back 11

Only if there is an increase in venous return.

This is normally the case when there is increased contractility due to sympathetic discharge.

Front 12

An increase in preload associated with increased contractillity allows the heart to increase __________

Back 12

stroke volume.

Front 13

Define afterload.

Back 13

The force against which the ventricle must work to eject blood.

Front 14

Afterload is determined by (2):

Back 14

Peripheral vascular resistance

Aortic compliance

Front 15

Afterload for the left ventricle is usually estimated by ___________

Back 15

Systolic blood pressure

Front 16

How does afterload affect stroke volume?

Back 16

Will initially decrease stroke volume, by causing an increase in Ventricular End Systolic Volume (VESV).

Front 17

How does the heart compensate for increased afterload?

Back 17

There is an increase in LVESV, which leads to an increase in LVEDV allowing the heart to maintain stroke volume.

Front 18

How does an increase in afterload affect left ventricular pressures?

Back 18

Left ventricular pressures are increased.

Front 19

How does an increase in afterload affect MVO2?

Back 19

MVO2 is increased.

Front 20

In diseased hearts, increased afterload can cause what?

Back 20

Decreased stroke volume due to the inability of the myocardium to respond to increased metabolic demands

Front 21

The afterload on cardiac muscle determines the ________ that the cardiac cell must develop before __________ can occur.

Back 21

Force

Shortening

Front 22

Afterload and shortening are _______ related

Back 22

Inversely

Front 23

Preload compensation becomes ineffective when aortic pressures rise above __________

Back 23

180 mmHg

Front 24

Name five factors that can increase myocardial contractility

Back 24

1 Increased extracellular calcium concentration

2 Increased plasma levels of epi and norepi

3 Increased sympathetic nervous system activity

4 Decreased hydrogen ion concentration (increased pH)

5 Many drugs (digitalis, inotropes, ect...)

Front 25

Name six factors that can decrease myocardial contractility

Back 25

1 Decreased extracellular calcium concentration

2 Decreased plasma levels of norepi and epi

3 Decreased sympathetic nervous system activity

4 Increased extracellular hydrogen ion concentration (decreased pH)

5 Many drugs (beta blockers, ect...)

6 Decreased oxygen supply

Front 26

Name two acute cardiac reserve mechanisms

Back 26

1. Increased heart rate

2. Increased stroke volume

-from increased end diastolic volume (preload)

-from decreased end systolic volume (contractility)

Front 27

Describe chronic cardiac reserve mechanisms

Back 27

Increased ventricular mass (hypertrophy)

Front 28

Ventricular chamber dialation is known as ____________

Back 28

eccentric hypertrophy

Front 29

Eccentric hypertrophy may be caused by (2)

Back 29

Aortic insufficency

Mitral regugitation.

(due to a backflow of blood and the need for larger stroke volumes)

Front 30

How does eccentric hypertrophy occur?

Back 30

Due to an ellongation of myocardial fibers and capillaries.

Front 31

Increase left ventricular mass due to eccentric hypertrophy is accompanied by an increase in____________

Back 31

Oxygen requirements

(due to increased wall tension and stroke volume)

Front 32

Eccentric hypertrophy results in __________ ventricle radius, and ____________ wall thickness

Back 32

Larger radius

The same wall thickness

Front 33

Concentric hypertrophy is caused by excessive ___________

Back 33

afterload

Front 34

Name two conditions that can cause concentric hypertrophy:

Back 34

Aortic stenosis

Hypertension

Front 35

Concentric hypertrophy results in increased ____________ and ____________

Back 35

cell diameter

capillary diffusion distance