Flashcards in CVT 101 Cardiac Hemodynamics Deck (128)
ionic exchange with sodium and potassium.
Define Repolarization :
normal resting cell potential
Define P Wave :
Define QRS :
Define T wave:
If we do not have repolarization, there will be no mechanics or electrical.
Define Systole & Diastole :
Systole: contraction of the ventricles (left side of the heart mainly because it is our systemic pump but we also have a stroke volume and cardiac output on our right side.)
Diastole: relaxation of the heart.
When does systole end and diastole begin?
end of the T is the end of systole, beginning of diastole
When something ends, something begins.
What throws off our electrolytes and what does that have to do with our conduction system?
Electrolytes. If we have to much potassium or salt, we are interfering with our conduction system.
If a patient takes to many diuretics or to much of there medication it could cause arrhythmia's, CHF.
Pressure curves for the LA and RA are:
identical but the mmHg scale will be different
The pressures in the LA and RA will depend on :
1. chamber size, compliance
2. presence of disease,
valvular disease or cardiomyopathy
3. ejection fraction
Chamber size and compliance of the left and right atrium.
(Compliance meaning is the chamber able to relax enough.)
If the myocardium (sarcomeres) of the right or left atrium dilate and stretch it causes fibroses and scars. They are not designed to stretch that far.
They become ineffective chambers and non compliant so the pressure goes up and the ejections fraction starts to decrease.
What events lead to myocardial contraction ?
a. Conduction which is depolarization and repolarization
b. at the cell level or ionic exchange
c. loading conditions, (HR, blood pressures, intracardiac pressures)
d. actin, myosin, sarcomeres
Normal RA pressure :
Normal LA pressure :
Components for both the RA & LA :
* a wave is the result of :
* x Decent is early atrial relaxation:
* c wave occurs during RA & LA filling :
* x’ decent:
* v wave occurs due to:
* Y decent:
*a wave: occurs after the P wave. The result of atrial contraction. The right and left atrium contracts and delivers an additional amount of blood to the right and left atrium so I have an increase in volume (only contributes about 10-15%)
*x decent: relaxing and filling. Depolarization.
*c wave: MV & TV move / bulge into the RA & LA due to changes in the dimensions . RA & LA are filling and relaxin
*x' decent: is late atrial relaxation
*v wave: an increase in atrial pressure due to RA / LA filling where it reaches a peak and is higher than the RV/LV pressure , the TV/MV open leading to rapid passive filling.
*Y decent: the TV / MV are open with the continuation of rapid passive filling to diastasis
Atrial pressure tracing
A wave: occurs after the P wave. The result of atrial contraction. a wave is active ventricular filling.
X descent: relaxing and filling. Depolarization.
C wave: slight bump in pressures because the annulous is moving
X’ descent: End of T wave. Atria continuous drop in pressure.
V wave: V for Volume- atria are being filled.
When they are at their fullest they create the V wave. When we have all of this volume in the R and L atrium, the valves open. Slightly delayed after the T wave.
Y descent: Rapid passive filling. The pressures start to fall because atria are delivering the stoke volume to the ventricle. Called diastase's. When the mitral valve opens there is rapid passive filling. The Mitral valve starts to close due to diastasis from the decrease in pressure. There is still blood flow through the mitral valve then at the end of diastases there is an A kick. generates an A wave, done with diastole, and the mitral valve closes.
How much stroke volume is delivered by the A kick?
A kick delivers about 10-15% to the total stroke volume to the LV. It depends on size of the atrium.
How often is the left atrium and right atrium being filled and by what?
Left atrium is continuously being filled by the pulmonary veins
Right atrium is being filled with the IVC and SVC
Whats happening during IVCT?
all of the valves are closed. end of diastole, beginning of diastole.
IVCT happens just before systole.
What is happening at the cell membrane?
You have stress in the walls going up because the walls have to overcome the pressure, ionic change at the cell level. Pressure in the LV starts to drop at the end of systole because the stroke volume is going out the AO. The the LV pressure is less than the LA pressure the valve closes.
What helps propagate and deliver a stroke volume?
Aortic root helps propagate our stroke volume. The tunica media takes the blunt force to help deliver the stroke volume.
ICVT is during:
end of diastole beginning of systole
IVRT is during:
end of systole beginning of diastole
What opens the AO and PV?
The pressures in the LV and RV
How long is IVCT and IVRT during the cardiac cycle?
IVRT and IVCT are about 0.4 milli seconds
4 stages of diastole
2. rapid passive filling
4. A kick
pulmonary wedge pressure:
same as the LA
what is the refractory period?
time when the ventricles repolarized
no stimuli can affect the ventricle.
normal pressure in the vena cava?