McCumbee - Ventricular Function Flashcards
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
Atrioventricular valves prevent the backflow of blood into the atria during ventricular systole, what are the two atrioventricular valves
Tricuspid valve
Mitral valve
Prevent the backflow of blood from the aorta and pulmonary arteries into the ventricles during ventricular diastole
Semilunar valves
Blood flows through the semilunar valves at _____ velocity than the AV valves
Greater
This is bc semilunar valves have smaller openings than AV valves
Phases of ventricular diastole
Isovolumic relaxation
Rapid ventricular filling
Reduced ventricular filling (diastasis)
Atrial systole
Ventricular systole, the period of ventricular contraction, is divided into which phases?
Isovolumic contration
Rapid ejection
Reduced ejection
Vibrations produced by the closure of the atrioventricular valves are responsible for what heart sound
S1 (first heard)
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
About _____ % of stroke volume is ejected during rapid ejection
70
Closure of the __________ signals the start of diastole
Semilunar valves
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
In the reduced ejection phase, the second heart sound (S2) is heard. It is caused by closure of
The semilunar valves
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
The volume of blood remaining in ventricles after ventricular contraction
End systolic volume
LVESV
S1 is produced by?
Closure of the atrioventricular valves at the onset of ventricular systole
S2 is produced by?
Closure of the semilunar valves at the end of the ventricular systole
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
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
A stenotic semilunar valve can cause an
Ejection murmur
Sounds generated by turbulent blood flow
Murmurs
The narrowing of the valve: blood flows at a higher velocity through the constricted opening
Stenosis
The backward flow of blood through a valve which fails to close properly
Regurgitation
Sounds created by turbulent blood flow in blood vessels are normally called
Bruits
Pressure changes in the right atrium can be observed through lookin at distention of the right internal jugular vein caused by:
Retrograde blood flow
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?
- There is less time for venous return: this tends to reduce cardiac
output. - 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
