Arterial pressure curves

Question 1

Normal Ao systolic/diastolic pressure values

Answer 1

• Ao systolic pressure: 90-140mmHg
• Ao diastolic pressure: 60-90mmHg

Question 2

Aortic waveform appearance

Answer 2

Rapid upstroke → systolic peak → clear dicrotic notch (AoV closure)

Question 3

Peripheral arterial waveform appearance

Answer 3

steeper upstroke with narrow systolic portion → ↓/absent dicrotic notch
* Systolic upstroke: 120-180ms after R wave on QRS

Question 4

Peak systolic P of arterial waveform

Answer 4

= peak LV systolic pressure
o Unless obstruction w/I LV, AoV or proximal Ao

Question 5

Dicrotic notch: cause and differences in arterial tree

Answer 5

dip on downslope due to pressure decline w AoV snapping shut
o Incisura: dicrotic notch from central Ao → sharply defined
 Low point of dicrotic notch
o Peripheral arteries: smoother dicrotic notch
 Approximates AoV closure
 Depends on arterial wall properties

Question 6

Anacrotic notch: cause

Answer 6

upslope of arterial pressure → bisferiens pulse (2nd systolic notch)
o Semilunar valve opening
o Results from turbulent flow during ejection
 AI, AS, HOCM → may overestimate BP

Question 7

mean arterial P equation

Answer 7

o Area under the curve/beat period and averaged on several beats
o Morphologic curve difference btw Ao and peripheral arteries → MAP is ↑ in Ao

MAP = diastolic BP + 1/3 pulse pressure

Question 8

What phase of systole will have small rise in P

Answer 8

IVCT of LV

Question 9

Measured pressure is a summation of 2 components

Answer 9

• Forward flow
• Reflected waves: from blood meeting areas of resistance (branching, tortuous vessels)
  o Reach AoV and reflected again in smaller waves → forward
• Sampled pressure waveform is a summation of all forward impulses
  o Less apparent is sample close to AoV
  o Usually negligible, but can be significant under certain circumstances

Question 10

When are reflected waves apparent

Answer 10

 Late Ao waveform
 More pronounced in periphera arteries waveform → peak systolic pressure > 10-20mmHg due to peripheral amplification from reflected waves

Question 11

Factors incr reflected waves

Answer 11

 CHF
 AI
 Systemic hypertension
 ↑Ao stiffness from ↑age/peripheral vascular dz
 Ao/iliofemoral obstruction
 Tortuosity and arterial vasoconstriction

Question 12

Factors decr reflected waves

Answer 12

 Vasodilation
 Hypovolemia
 Hypotension

Question 13

PCWP: how to measure and what does it tell

Answer 13

• End-hole KT advanced to distal PA branch → occlude forward flow
  o Reflect PVs, LA, LV diastolic pressures
  o Pressure changes in LA transmitted to distal KT tip with time delay

Question 14

Normal PCWP waveform

Answer 14

similar to LA and RA waveform
o a (LA systole) and v (LA filling) waves
 c wave (MV closure) may be present, can get lost in retrograde transmission
o x (LA relaxation) and y (LA emptying) descent
o Normal pressure = 4-12mmHg

Question 15

PCWP limitations

Answer 15

Artifacts: over/underwedge
Not equivalent of LVEDP in certain conditions

Question 16

PCWP underwedge

Answer 16

incomplete occlusion of PA → hybrid PA/PAWP waveform
* Variation from PA to PAW with respiration

Question 17

PCWP overwedge

Answer 17

over or eccentric inflation of balloon/ distal location of KT
* ↑/damped or inaccurate PAWP
* Linear ↑ in pressure waveform

Question 18

PAWP do NOT = LV EDP with these conditions

Answer 18

 Mitral stenosis
 LA myxoma
 Pulmonary venous obstruction
 ↓ ventricular compliance
 ↑pleural pressure
 KT tip in non dependent zone of the lung

Question 19

Difference with direct LA measurements

Answer 19

o Delay in pressure transmission vs direct LA measures
o Follow ECG event by 200-240ms

Question 20

PCWP waveform w/ MS

Answer 20

o ↑a wave → resistance to filling + ↑ force of contraction to push blood through stenotic valve
o Prolonged y descent → ↑ resistance to passive filling

Question 21

PCWP waveform w/ MR

Answer 21

• ↑v wave
  o Giant in acute MR → non compliant LA cannot accommodate large amount of MR
   Ruptured papillary muscle
  o Mild or moderate with chronic MR

Question 22

LV PG w PAWP and LAP

Answer 22

• PAWP: delay in transmission of change in pressure contour and phase shift
  o Gradient of PAWP overestimated in KT lab
  o LV/PAWP PG =15mmHg vs LV/LAP PG = 6mmHg

Question 23

Impulse or instantaneous gradient

Answer 23

o Measured with Doppler on echo
o Highest PG during systole
 Ao systolic P is reached later in systole → discrepancy of instantaneous vs peak to peak
o Early systolic gradient due to high flow state in LVOT/RVOT → 5mmHg

Question 24

Peak to peak gradient

Answer 24

normal = 0mmHg
o Measured in cath lab
o Difference from peak LV and peak Ao
o SAS: instantaneous peak > peak to peak PG
o Dynamic LVOTO: instantaneous = peak to peak PG

Question 25

Mean gradient

Answer 25

average gradient