Transcript Pressures - Circulation

Right Heart Catheterization
Sripal Bangalore, M.D., M.H.A.
and
Deepak L. Bhatt, M.D., M.P.H., F.A.H.A
Copyright © 2011 American Heart Association.
Overview
Right Heart Catheterization (RHC)
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Indications
Contraindications / Caution
Equipment
Technique
Precautions
Cardiac Cycle
Pressure monitoring
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Zeroing and Referencing
Fast flush test/ Square wave test
Pressure wave interpretation
Cardiac output
Derived measurements
Copyright © 2011 American Heart Association.
Indications
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No universally accepted indication as right heart (pulmonary
artery, PA) catheterization has not been shown to improve
outcomes1
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However it is useful in the following diagnostic and therapeutic
applications
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Diagnostic
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Differentiation of various etiologies of shock and pulmonary edema
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Evaluation of pulmonary hypertension
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Differentiation of pericardial tamponade from constrictive pericarditis and restrictive
cardiomyopathy
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Diagnosis of left to right intracardiac shunts
Therapeutic
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1Sandham
Guide to fluid management and hemodynamic monitoring of patients after surgery,
complicated myocardial infarction, patients in shock, heart failure, etc.
JD et al. A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med 2003;348(1):5-14
Contraindications / Caution
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No absolute contraindications for use of PA catheter.
Extreme care needed particularly in patients with
severe pulmonary hypertension and in the elderly
Fluoroscopic guidance recommended in patients
with pre-existing left bundle branch block (risk of
complete heart block if right bundle damaged during
catheter insertion)
Copyright © 2011 American Heart Association.
Equipment
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2% chlorhexidine skin prep
Sterile gown, gloves, hat and mask
Sterile drape
2% lidocaine solution for local anesthesia
Micropuncture needle and sheath (optional)
Sterile ultrasound probe cover and gel
Introducer sheath and needle
Pulmonary artery (Swan-Ganz) catheter
Sterile flush
Pressure tubing, transducer and monitor
Copyright © 2011 American Heart Association.
Equipment
Pulmonary Artery (Swan-Ganz) Catheter
These are 7F to 7.5F system catheters and are available as femoral vein
insertion to continuous cardiac output catheters
Balloon inflation valve
Balloon inflation syringe
Distal PA lumen hub
VIP lumen hub
Proximal injectate lumen hub
Thermistor connector
Reproduced with permission from Edward Lifesciences, Irvine, California
Copyright © 2011 American Heart Association.
Technique- Micropuncture
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Insertion site: Internal jugular vein, subclavian vein, antecubital vein, or
femoral vein
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After the site is prepped and draped, local anesthesia is administered at the
site by giving 5 to 10 cc (depending on the site) of 2% lidocaine using a 25G
needle
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Vein entered using a needle (preferably micropuncture) and preferably under
ultrasound guidance (especially for internal jugular vein)
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After ensuring that the needle is indeed in a vein (dark, non-pulsatile flow or
checking pressure or oxygen saturation), the guidewire is introduced into the
micropuncture needle and the needle exchanged for a micropuncture sheath
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If there is difficulty in wiring and the micropuncture wire needs to be
removed, remove both the needle and the wire as a unit
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Attempting to remove just the guidewire can result in the guidewire tip
shearing off the needle tip with subsequent guidewire embolization
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Exchange the micropuncture catheter for the introducer sheath
Copyright © 2011 American Heart Association.
Technique
Preparing the catheter
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Under sterile conditions, remove the pulmonary artery catheter from
the packaging
Flush the proximal and distal ports with saline to ensure an air free
system and place stopcocks on the ends
Fill the balloon inflation syringe with 1.5 cc of air and inflate the
balloon under saline to ensure no air leaks in the balloon
Prepare the pressure monitoring system for use according to
institutional practice, ensuring an air free system
Copyright © 2011 American Heart Association.
Inserting the catheter
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Technique
The pulmonary artery (PA) catheter can be inserted either under fluoroscopic
guidance (preferred) or under the guidance of the pressure wave forms
Fluoroscopic guidance is recommended in patients with markedly enlarged
RA or RV, severe tricuspid regurgitation, or in those with left bundle branch
block
A PA catheter with the balloon inflated is designed to be flow-directed and will
follow the direction of blood flow (right atrium to pulmonary arteries)
The catheter should be advanced to the vena cava/RA junction, the
approximate distance (as measured on the PA catheter) from the site insertion
is below
Site of Insertion
Distal to the Vena Cava/RA junction (cm)
Internal jugular vein
15 to 20
Subclavian vein
10 to 15
Antecubital vein (Right)
35 to 40
Antecubital vein (Left)
45 to 50
Femoral vein
25 to 30
RA = right atrium
Copyright © 2011 American Heart Association.
Technique
Inserting the catheter
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Once the catheter tip reaches the junction of the vena cava and right atrium,
the balloon is inflated with 1.5 cc of air and the pressure waveforms noted
The following sequential waveforms will be noted as the catheter passes
through the cardiac chambers
 Right atrial (RA) waveform
a
x
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a
v
c
y
a
v
c
x
y
v
c
x
y
Right ventricular (RV) waveform
Copyright © 2011 American Heart Association.
Inserting the catheter
Technique
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Pulmonary artery (PA) pressure waveform
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Pulmonary capillary wedge pressure (PCWP) waveform
 Similar to RA pressure waveform except slightly higher
a c
x
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a c
v
y
a c
v
x
y
v
x
y
Normal insertion tracing will therefore appear as below
 For RV to PA - observe changes in diastolic pressure (increase) as
the systolic pressure stays the same
a
v
c
x
y
Copyright © 2011 American Heart Association.
Technique
Inserting the catheter
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Once a PCWP tracing is seen, deflate the balloon
The catheter should be withdrawn 1-2 cm to remove any redundant length or
loop in the RA or RV. Keep the tip in a position where full or near full
inflation volume is necessary to produce a wedge tracing
The balloon should be deflated and the pressure wave form seen should now
be that of the PA. If still the PCWP, it is likely that the catheter is distal and
should be retracted until a PA pressure tracing is seen
The ideal position of the catheter is the zone 3 region of the lung (lower zone)
For subsequent wedge tracings, the balloon should be inflated with the
minimum amount of air to produce a wedge tracing. Excess can cause
“overwedging” where the PCWP will be higher due to transmittal of pressure
from the balloon and with loss of characteristic waveforms
Removing the catheter
 The catheter should always be removed with the balloon deflated to avoid
damaging the valves
Copyright © 2011 American Heart Association.
Technique
Precaution
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Always advance the catheter with the balloon inflated (catheter is flow-directed, also
reduces ventricular irritability and ectopy)
Never leave the catheter wedged in the PA for longer than necessary, to avoid the risk
of pulmonary artery rupture/pulmonary infarction
Do not overinflate the balloon
If wedge is obtained at volumes <1.0cc, pull the catheter back to a position where full
or near-full inflation volume (1.0 to 1.5cc) produces a wedge tracing
Before balloon reinflation, always check the waveform to ensure no distal migration
Never withdraw the catheter with the balloon inflated to avoid valvular damage
Never use fluids (saline) to inflate the balloon
In situations where multiple attempts at advancing the catheter to the PA fail, a 0.025”
guidewire can be used under fluoroscopic guidance to help advance the catheter to the
PA
Always maintain catheter tip in a main branch of the PA
If performed via the internal jugular or the subclavian vein route and without
fluoroscopic guidance, chest x-ray should be obtained post procedure to rule out
pneumothorax and to verify catheter position
Never flush catheter with balloon wedged in the PA
Copyright © 2011 American Heart Association.
Cardiac
Cycle
Time (msec)  0
100
200
300
400
500
600
700
800
QRS
Complex
EKG
T
P
P
Left Sided
Pressures
120
9
0
Pressure
(mm Hg)
6
0
Aorta
Dicrotic
Notch
Left Ventricular
Pressure
3
0
v
c
Left Atrial
Pressure
a
y
x
0
Atrial
Systole
Ventricular Systole
Ventricular Diastole
Cardiac
Cycle
Time (msec)  0
100
200
300
400
500
600
700
800
QRS
Complex
EKG
T
P
P
Right Sided
Pressures
30
PA Pressure
Dicrotic
Notch
Pressure
(mm Hg)
1
5
Right Ventricular
Pressure
v
c
Right Atrial
Pressure
a
y
x
0
Atrial
Systole
Ventricular Systole
Ventricular Diastole
Pressure Recordings
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Always record pressure at end expiration (except in patients on PEEP)
Under normal conditions, pressures will be lower in inspiration due to
decrease in intrathoracic pressure
Before any pressure measurements are taken, it is imperative to perform
zeroing and referencing of the system
 Zeroing- accomplished by opening the system to air so as to equilibrate
with atmospheric pressure
 Referencing- accomplished by ensuring that the air-fluid interface of the
transducer is at the level of the patient heart (phlebostatic axis) (4th
intercostal space midway between anterior and posterior chest wall)
 For every inch the heart is offset from the reference point of the
transducer, a 2mm Hg of error will be introduced. If the heart is
lower than the transducer, the pressure will be erroneously low and if
the heart is higher, the pressure will be erroneously high.
Fast flush test/ Square wave testing
 The dynamic response of the pressure monitoring system is determined
by measuring the resonant frequency and the damping coefficient of the
system using the fast flush test
Copyright © 2011 American Heart Association.
Pressure Recordings
Optimal Damping
Fast flush test / Square wave testing
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Performed by briefly opening and closing the valve in the
continuous flush device
This produces a square ware pattern on the oscilloscope,
an initial steep rise followed by a plateau, followed by
steep fall below baseline which is then followed by
oscillations. The pattern determines optimal versus
suboptimal damping
Optimal damping- usually 1.5 to 2 oscillations before
returning to baseline. This is ideal
Over damping- None to <1.5 oscillations before retuning
to baseline. Common cause - air bubbles.
Underestimation of systolic pressure. Diastolic pressure
may not be affected
Under damping- >2 oscillations before returning to
baseline. Common cause - excessive tube length, multiple
stopcocks in the circuit, etc. Overestimated systolic
pressure and underestimated diastolic pressure
Over Damping
Under Damping
Copyright © 2011 American Heart Association.
Pressure Recordings
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Always record pressure at end expiration (except in patients on PEEP)
Under normal conditions, pressures will be lower in inspiration due to
decrease in intrathoracic pressure
PCWP reflects left atrial pressure and hence the left ventricular end diastolic
pressure as long as ventricular compliance is normal or unchanging
 PCWP > LVEDP: Mitral valve stenosis or regurgitation, left atrial
myxoma, pulmonary vascular disease/embolism, increased pulmonary
vascular resistance, cor pulmonale
 PCWP < LVEDP: Early stages of diastolic dysfunction, aortic
regurgitation, decreased ventricular compliance due to myocardial
ischemia/infarction, positive pressure ventilation, etc.
Site
Normal Values
(mm Hg)
Mean Pressure
(mm Hg)
0-8
4
Right Ventricle
15-25/0-8
5-12
Pulmonary Artery
15-25/8-12
10-20
PCWP
9-23/1-12
6-12
Right Atrium
PCWP = Pulmonary Capillary Wedge Pressure
Copyright © 2011 American Heart Association.
Pressure Wave Interpretations
RA/ PCWP
Wave pattern
Mechanism
Condition
Cannon ‘a’ wave
AV dissociation
Complete heart block, ventricular
tachycardia, AVNRT
Tall ‘a’ wave
Increased atrial pressure
Mitral or tricuspid stenosis
No ‘a’ wave
Loss of atrial kick
Atrial fibrillation
Tall ‘v’ wave
Increased volume during
ventricular systole
Mitral or tricuspid insufficiency,
VSD
Loss of ‘y’ descent
Equalization of diastolic
pressures
Cardiac tamponade
Exaggerated ‘y’
descent
Rapid diastolic filling
Constrictive pericarditis
AVNRT = Atrioventricular Nodal Reentry Tachycardia; VSD = Ventricular Septal Defect
Copyright © 2011 American Heart Association.
Cardiac Output
Three indirect methods for cardiac output determinations
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Dye indicator dilution technique
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Fick’s technique
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Cardiac Output = Oxygen consumption in ml/min
A-V Oxygen difference
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Oxygen consumption measured using an oxygen hood
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Normal oxygen consumption is 250 ml/min
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A-V Oxygen difference = 13.4 x Hgb concentration x (SaO2-SvO2)
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Most accurate in low output states and is considered the gold standard
Thermodilution technique
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Known amount of solution (usually saline) is injected into the proximal
port (right atrium) and mixes and cools the blood which is recorded by
a thermistor located at the distal end of the catheter
Copyright © 2011 American Heart Association.
Cardiac Output
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Thermodilution technique
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CO is inversely proportional to the area under the curve
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Not reliable in patients with severe tricuspid or pulmonic valve
regurgitation. Results in lower peak and a prolonged washout phase due
to re-circulation resulting in underestimation of CO
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Not reliable in patients with intra-cardiac shunts. Overestimates CO
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Normal CO = 4 - 8L/min
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Normal cardiac index (cardiac output indexed to body surface area) =
2.5 - 4.0 L/min/m2
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Oxygen saturation (SO2) obtained from the PA is a rough measure of CO
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PA SO2 >80  High CO (shunt, sepsis, etc.)
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PA SO2 65-80  Normal CO
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PA SO2 <65  Low CO
Copyright © 2011 American Heart Association.
Derived Parameters
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Vascular resistance obtained is least accurate and most sensitive to minor
inaccuracies in data acquisition
Parameter
Formula
Normal Values
(MAP-RAP) x 80
CO
700 to 1600 dynes/sec/cm2
(9-20 Wood Units)
Pulmonary Vascular
Resistance
(MPAP-PCWP) x 80
CO
20 to 120 dynes/sec/cm2
(0.25-1.5 Wood Units)
Stroke Work Index
(MAP-LVEDP) x SVI x 0.0136
45 to 75 gm-m/m2/Beat (LV)
5 to 10 gm-m/m2/Beat (RV)
(SaO2- MvO2)
(PvO2-PaO2)
1
Mitral Valve Area
(Gorlin’s Equation)
CO (ml/min)
37.7 x DFP x HR x √ΔP
4 to 6 cm2
Aortic Valve Area
(Gorlin’s Equation)
CO (ml/min)
44.3 x SEP x HR x √ΔP
3 to 4 cm2
CO (l/min)
√ΔP
3 to 4 cm2
Systemic Vascular Resistance
Shunt Fraction
Aortic Valve Area
(Modified Hakki Equation)
CO = Cardiac Output; DFP = Diastolic Filling Period; HR = Heart Rate; LVEDP = Left Ventricular End Diastolic Pressure; MAP = Mean Arterial Pressure; MPAP =
Mean Pulmonary Artery Pressure; MvO2 = Oxygen saturation mixed venous; PaO2 = Oxygen saturation pulmonary artery; PCWP = Pulmonary Capillary Wedge
Pressure; PvO2 = Oxygen saturation pulmonary veins; RAP = Right Atrial Pressure; SaO2 = Oxygen saturation arterial; SEP = Systolic Ejection Period; SVI = Stroke
Volume Index.
Copyright © 2011 American Heart Association.
Constriction vs. Restriction
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Hemodynamic parameters that help differentiate constrictive pericarditis versus
restrictive cardiomyopathy
Parameter
Constrictive Pericarditis
Restrictive Cardiomyopathy
LVEDP-RVEDP, mm HG
≤5
>5
RV Systolic, mm Hg
≤ 50
> 50
RVEDP/RVSP, mm Hg
≥ 0.33
< 0.3
RV/LV interdependence
Discordance
Concordance
Elevated with equalization of diastolic
pressures
Elevated with equalization of
diastolic pressures
Dip and plateau (Square root sign)
Dip and plateau (Square root sign)
RA pressure waveform
Prominent y descent
Prominent y descent
PCWP/LV respiratory
gradient
≥5
<5
Pressures
RV/LV pressure waveform
LVEDP = Left Ventricular End Diastolic Pressure; PCWP = Pulmonary Capillary Wedge Pressure; RA = Right Atrial; RVEDP = Right Ventricular End Diastolic
Pressure; RVSP = Right Ventricular Systolic Pressure.
Copyright © 2011 American Heart Association.