Cardiac Cycle Flashcards
Order of atrial contraction
Right first, then left; SA node on right side
order of ventricular contraction
Left side first, fibers reach it first
Order of ventricular ejection (start and end)
Right ventricle ejects first, b/c pulmonic circulation is at lower pressure; left ventricle finishes first because it can generate more contractile force
JVP waveform (all letters)
A wave - atrial contraction peak; end carotid pulse
C wave - tricuspid wave peak as valve pushes against right atrium
X wave - atrial relaxation and refilling
X’ wave - ventricular systole pulls tricuspid out of the way
V wave - venous filling during closed tricuspid valve - follows carotid pulse
Y wave - emptying of the atrium into the ventricle
‘wedge’ pressure
measurement of the pulmonary venous pressure after placement of a balloon in the pulmonary artery
Arterial pressure wave theory
The peak pressure actually increases as one travels away from the aorta, but the wave becomes more condensed on the time scale. I.e. greater amplitude of the wave, shorter wavelength; reflections cause secondary peaks and for the abdominal aorta’s peak to occur at the moment when the 1st reflection wave travels through it
wave theory for atherosclerotic patients
stiffer walls means that reflected waves travel faster and the initial reflection comes back to the aortic valve before it closes, resulting in an increase in systolic pressure
time for pressure wave to reach femoral artery (or radial artery)
100 ms
PEAK pressure velocity
5-9 m/s
ACTUAL blood velocity
70-140 cm/s arterial 35-45 cm/s venous
incisura and dicrotic pressure wave
incisura refers to the abrupt change in slope on the pressure curve (a.k.a. dicrotic notch) and the dicrotic pressure wave is the secondary wave that follows
