Otto notes, Exam #2 Flashcards
Diastolic Filling and Function
isovolumic relaxation time is the interval from
aortic valve closure to MV opening (pressure in LV rapidly falls during this) opposite is true for IVCT, where a rapid rise in LV pressure occurs
isovolumic contraction time (IVCT) is the interval
between mitral valve closure and aortic valve opening
4 phases of diastole:
isovolumic relaxation, early rapid diastolic filling, diastasis, late diastolic filling caused by atrial contraction
When LV pressure falls below LA pressure, this opens and _______ ends.
MV
IVRT ends
at the end of IVRT, the MV opens. MV opening is followed by
rapid early diastolic filling with the rate and tie course of LA to LV flow determined by several factors, including the pressure difference along the flow stream, ventricular relaxation, and the relative compliances of the two chambers
following early diastolic filling, the ventricle fills, and pressures in the atrium and ventricle equalize, resulting in a period called ___________.
diastasis, during which little movement of blood between the chambers occurs and the MV leaflets remain in a semi open position.
the duration of diastasis is totally dependent on the
HEART RATE…
Can diastasis be absent completely at faster heart rates?
YES
With atrial contraction, (the last phase in diastole), _____ pressure exceeds _________ pressure, thus resulting in further ___________ opening and a second pulse of _________ filling.
LA
LV
MV leaflet
ventricular
Are the 4 phases of diastole as described exactly the same for both the LV and RV?
For the most part, YES!
ONE DIFFERENCE… the duration of diastole for the RV is is slightly shorter in normal individuals because of a slightly longer systolic ejection period
the 3 most clinically relevant parameters of diastolic function are
ventricular relaxation, myocardial or chamber compliance, filling pressures
LV relaxation is not passive as it involves
the use of energy by the myocardium.
LV relaxation occurs during when
occurs during isovolumic relaxation and the early diastolic filling period
isovolumic relaxation includes internal loading forces such as _________ and external conditions such as _________, and inactivation of myocardial contraction (metabolic, neurohumoral, and pharmacologic)
internal: cardiac fiber length
external: wall stress, arterial impedance
abnormal ventricular relaxation results in prolongation of the______, a slower rate in decline in _________________, and a consequent reduction in the _____________.
IVRT
ventricular pressure
early peak filling rate (due to a smaller pressure difference between the atrium and the ventricle when the AV valve opens)
Measures of LV relaxation (3)
IVRT
maximum rate of pressure decline (-dP/dt)
time constant of relaxation (tau)
tau reflects what
reflects the rate of pressure decline from the point of maximum -dP/dt to mitral valve opening
ventricular relaxation is one of many factors that indirectly affect
peak rapid filling
compliance is the ratio of
change in volume to change in pressure (dV/dP)
what is the inverse of compliance?
stiffness; it is the ratio of change in pressure to change in volume (dP/dV)
conceptually, compliance can be divided into two heart components
- myocardial components
- chamber components (influenced by ventricular size/shape)
extrinsic factors can also affect compliance (ex. pericardium, RV volume, pleural pressure)
Diastolic “filling” pressures include (2)
LV end-diastolic pressure
mean LA pressure
LV end diastolic pressure reflects ________ pressure after _________ is complete.
ventricular, filling
LA pressure reflects the average pressure in the LA during __________.
diastole
Clinically LA pressure is estimated by the (2)
- pulmonary wedge pressure - single point (cath lab)
- Swan-Ganz indwelling right heart catheter - multiple points (cath lab)
remember, ventricular DIASTOLIC FUNCTION and DIASTOLIC FILLING are not the same exact thing. The park early diastolic filling rate will be affected by (3)
- changes in preload that affect the initial pressure difference between the ventricle and atrium (increased with volume loading, decreased with volume depletion)
- change in transmitral volume flow rate (ex increased with coexisting mitral regurgitation)
- change in atrial pressure (ex elevated LV end-diastolic pressure or a v-wave caused by MR)