McCumbee - Ventricular Function Flashcards by Dylan Weaver

At rest, the atrial systole acounts for about 10-15% of the ventricular filling. In vigorous exercise, atrial systole is responsible for up to _____ %

40% of ventricular filling

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Atrioventricular valves prevent the backflow of blood into the atria during ventricular systole, what are the two atrioventricular valves

Tricuspid valve

Mitral valve

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Prevent the backflow of blood from the aorta and pulmonary arteries into the ventricles during ventricular diastole

Semilunar valves

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Blood flows through the semilunar valves at _____ velocity than the AV valves

Greater

This is bc semilunar valves have smaller openings than AV valves

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Phases of ventricular diastole

Isovolumic relaxation

Rapid ventricular filling

Reduced ventricular filling (diastasis)

Atrial systole

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Ventricular systole, the period of ventricular contraction, is divided into which phases?

Isovolumic contration

Rapid ejection

Reduced ejection

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Vibrations produced by the closure of the atrioventricular valves are responsible for what heart sound

S1 (first heard)

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Four parts of rapid ejection phase

Ventricular pressure continues to rise
Pressures w/in aorta & pulm A. Increase
Blood flow from ventricles into aorta and pulmonary artery peaks
Ventricular volume decreases

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About _____ % of stroke volume is ejected during rapid ejection

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Closure of the __________ signals the start of diastole

Semilunar valves

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A slight upward deflection in the pressure tracing during the falling phase caused by the closure of the semilunar valves. Used in pressure tracing to mark the end of the ventricular systole

Dicrotic notch

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In the reduced ejection phase, the second heart sound (S2) is heard. It is caused by closure of

The semilunar valves

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During the isovolumic relaxation, intraventricular pressure drops rapidly.
Why does intra aortic pressure not drop abruptly?

Resistance to blood flow from smaller arteries in the vascular tree

Elastic recoil of these vessels which helps maintain pressure

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The volume of blood remaining in ventricles after ventricular contraction

End systolic volume

LVESV

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S1 is produced by?

Closure of the atrioventricular valves at the onset of ventricular systole

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S2 is produced by?

Closure of the semilunar valves at the end of the ventricular systole

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S4 is heard during

Contraction of the atria during late diastole.

Commonly associated w/ resistance to filling and is often a sign of diastolic heart failure.

Rarely a normal sound

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When does S3 occur?

In early diastole during the passive filling of the ventricle

Caused by blood hitting the ventricular wall

May be normal in a young person. Often sign of heart failure in adults over 40

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A stenotic semilunar valve can cause an

Ejection murmur

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Sounds generated by turbulent blood flow

Murmurs

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The narrowing of the valve: blood flows at a higher velocity through the constricted opening

Stenosis

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The backward flow of blood through a valve which fails to close properly

Regurgitation

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Sounds created by turbulent blood flow in blood vessels are normally called

Bruits

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Pressure changes in the right atrium can be observed through lookin at distention of the right internal jugular vein caused by:

Retrograde blood flow

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Normal Jugular pulse: pressure decline assoc’d with right atrial relaxation

X descent

Normal jugular pulse: venous distention caused by back pressure associated with right atrial contraction Atrial systole

‘A’ wave

Normal jugular pulse: Interrupts x descent. Caused by tricuspid valves closing and bulging into right atrium at onset of isovolumic ventricular contraction

C wave

Normal jugular pulse: upward swing caused by filling of right atrium behind the closed tricuspid valve. Venuous collection

V wave

Normal jugular pulse is caused by the rapid flow of blood into the right ventricle when the tricuspid valve opens at the end of the isovolumic relaxation phase.

Y-descent

Implications of the reduced duration of diastole during tachycardia?

1. There is less time for venous return: this tends to reduce cardiac output. 2. Because the coronary vessels of the myocardium are compressed during systole, most perfusion of myocardium occurs during diastole. Since the duration of diastole decreases with increasing heart rate, perfusion of the myocardium will be less effective in tachycardia.

the stretch on ventricular muscle fibers just before contraction. In the intact heart, preload results from the stretching of muscle fibers by the volume of blood contained within the ventricle at the end of diastole. For the beating heart, end diastolic volume (EDV) and the end diastolic pressure (EDP) are good indices of preload.

Preload

the resistance that the ventricle has to overcome in order to eject blood into the vasculature: the force that the sarcomere must overcome in order to shorten during systole

Afterload

an intrinsic property of the myocardium that | accounts for changes in the strength of contraction when preload and afterload are unchanged.

Contractility

volume of blood ejected from a ventricle during a | single contraction.

Stroke volume (SV)

the volume of blood in the ventricle at the | end of ventricular filling. EDV is used as a measure of ventricular preload.

End diastolic volume

the volume of blood left in the ventricle at | the end of ejection.

End systolic volume

the fraction of the end-diastolic volume that is ejected | from the ventricle during systole.

Ejection fraction

the volume of blood ejected by the ventricle per min.

Cardiac output

the ratio of change in volume (ΔV) to change in pressure (ΔP); the ability of a hollow organ to distend and increase volume in response to increasing transmural pressure (inside pressure minus outside pressure).

Compliance

represents the maximum pressure that the ventricle can develop for any given ventricular volume at a given inotropic state.

End-systolic pressure-volume relationship (ESPVR)

relationship between pressure and volume in the ventricle at the moment the ventricle is completely relaxed (End Diastole)

End-diasolitc pressure-volume relationship (edpvr)

Cardiac rate

Chronotropy

Relaxation of the myocardium

Lusitropy

EF is normally greater that

55%

The EF increases with _______ contractility

Increasing

Change in volume ___—— Change in pressure

Compliance

Change in pressure ———- Change in volume

Elastance

Elastance is the _____ of compliance

Reciprocal

Compliance reflects what in a ventricle

The relative ease with which the ventricle can fill with blood

In cardiac hypertrophy, the increased ventricular thickness ______-___ ventricular compliance

Decreases

Ischemic heart injury is characterized by a transitory ________ of relaxation during diastol

Inhibition

The slope of End Systolic Pressure-Volume Relationship graph is an index of ___-___

Myocardial contractility

The slope of end systolic pressure-volume relationship will shift if _________

Contractile state changes

The End-Systolic Pressure-Volume Relationship is relatively insensitive to

Changes in preload, afterload, or heart rate

When contractility and preload are held constant, and increase in afterload results in

Reduced stroke volume and a higher end-systolic volume

If preload and afterload are held constant, an increase in contractility will cause the slope of ESPVR to

Become steeper and move leftward

Conditions that affect ventricular filling

``` Total blood volume Skeletal muscle pump Body position Atrial kick(exercise) Venous tone Intrapericardial pressure Intrathoracic pressure ```

Inspiration _____ the pressure gradient for venous return to the right atrium

Increases

The buildup of intrapericardial fluid during a pericardial infection will ______ cardiac filling

Limit

Circulating catecholamines and sympathetic stimulation _____ the contractility of cardiac muscle

Enhance

Cardiac ischemia and acidosis ______ contractility

Decrease

______ is the major determinant of afterload

Vascular resistance

The work done by a ventricle to eject a volume of blood Equal to stroke volume times the intraventricular pressure generated during ejection

Stroke work

Cardiac work

Stroke work (x) heart rate

The total mechanical energy generated by a single heart beat is given by

Pressure-volume area | Stroke work + Eleastic potential energy

The ratio of useful energy produced by the heart to myocardial oxygen consumption

Mechanical efficiency of the heart

The amount of a substance entering an organ at a given time minus the amount of substance leaving the organ at a given time is equal to the amount of substance used by an organ during the same time periord

Fick Principle

What three measurements must you have to use the fick method to determine cardiac output?

O2 consumed by whole body O2 concentration of pulm venous blood O2 concentration of arterial blood

A specialized soft catheter with multiple lumens and a balloon tip used in the thermodilution method of calculating cardiac output

Swan-ganz catheter

Method for calculating cardiac output that uses a small thermometer in the pulmonary artery and a computer program to calculate the right cardiac output from change in blood temperature and the volume and temperature of a known saline solution that was injected into the right atrium

Thermodilution method

The cardiac output per square meter of body surface area

Cardiac index

Normal amount of pericardial fluid that is found in between the serous layers?

15-20mL