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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3597_Библиотеки_им_академика_М_И_Перельмана
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3 —
Coronary Angiography and Ventriculography 173
drugs (NSAIDs), and cyclooxygenase-2 (COX-2) inhibitors 24
hours preprocedure. The aforementioned medications may be
resumed at 24 hours postprocedure.
c. Hold Metformin until 48 hours postprocedure or until creatinine
is stable.
d. Minimize contrast use (biplane imaging in the catheterization
laboratory, if possible).
e. Consider using a nonionic, isosmolar contrast.
f. Check serum creatinine at 48 hours postprocedure.
3. GFR or CrCl less than 30 mL/min
a. IV hydration recommendations (50 mEq NaHCO3 in 1 L NaCl
0.45%)
b. For inpatient cases*:
i. Preprocedure: 1 mL/kg/hour × 12 hours
ii. Postprocedure: 1 mL/kg/hour × 12 hours
†
†
c. For same-day cases*:
i. Preprocedure: 3 mL/kg/hour × 1 hour (maximum rate =
330 mL/hr)
ii. Postprocedure: 1 mL/kg/hour × 6 hours
d. Hold ACE inhibitors, angiotensin receptor blockers, diuretics,
NSAIDs, and COX-2 inhibitors 24 hours before the procedure.
The aforementioned medications may be resumed at 24 hours
postprocedure.
e. Hold Metformin until 48 hours postprocedure or until creatinine
is stable.
f. Minimize contrast use (biplane imaging in the catheterization
laboratory, if possible).
g. Use a nonionic, isosmolar contrast.
h. Check serum creatinine at 48 hours postprocedure.
Cautionary Note
1. Patients who are at risk for development of fluid overload should
be given less IV hydration and observed carefully for development
of heart failure.
2. Avoid repeat contrast exposure. Delay angiography until serum
creatinine level has peaked and stabilized.
a. In patients with diabetes and renal disease, delay angiography
>72 hours.
b. In patients with no risk factors, delay angiography >48 hours.
Suggested Readings
Balter S: Radiation safety in the cardiac cat heterization laboratory: operational radiation
safety. Catheter Cardiovasc Interv 47(3):347–353, 1999.
Best PJ, Skelding KA, Mehran R, et al: SCAI consensus document on occupational radia-
tion exposure to the pregnant cardiologi st and technical personnel. Catheter Cardiovasc Interv 77:232–241, 2011.
Klein L, Sheldon MW, Brinker J, et al: The use of radiographic contrast media during PCI:
a focused review: a position statement of the Society of Cardiovascula r Angiography
and Inter vention. Catheter Cardiovasc Interv 74:728 –746, 2009.
To view Videos 3-1, 3-2, and 3-3, please activate your book on
www.ExpertConsult.Inkling.com using the pincode
*Emergent procedure: One dose preprocedure and three doses postprocedure
is acceptable.
†
IV hydration for 6 to 12 hours preprocedure and/or for 6 to 12 hours postpro-
cedure can be considered.
on the inside front cover.
https://t.me/med1917
For more information, see Videos 3-1, 3-2, and 3-3.
3 —
Coronary Angiography and Ventriculography 173.e1
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Hemodynamic Data
MORTON J. KERN • NAVIN K. KAPUR
In addition to anatomic information through angiography, cardiac
catheterization provides equally important functional information
through the recording of hemodynamic data of pressure measurements, cardiac output (CO), and blood oximetry.
Pressure Waves in the Heart
Blood within the heart and vessels exerts pressure. A pressure wave
is created by cardiac muscular contraction and is transmitted from the
heart chambers through the vessels. This wave can be measured by
a catheter, a closed fluid-filled column connected to a pressure transducer that converts mechanical pressure to an electrical signal that is
displayed on a video monitor.
Cardiac pressure waveforms are cyclical, with the pressure rising
and falling from the onset of one cardiac contraction (systole) to
the onset of the next contraction. The complete description of cardiac physiology can be found elsewhere, but an examination of the
cardiac cycle, electrocardiogram (ECG), and corresponding pressures
(Figs. 4-1 and 4-2) provides a starting point to understand basic hemodynamics in the cardiac catheterization laboratory.
Collection of hemodynamic data is an integral part of every catheterization protocol. Even complex hemodynamic data recording can
be accomplished accurately and rapidly if an efficient method is consistently used in the laboratory. A measurement sequence used in our
laboratory is shown in Boxes 4-1, 4-2, and 4-3. This sequence facilitates
simultaneous pressure measurements across the heart, concentrating
on the aortic (Ao) and mitral valves, which are the most commonly
affected by disease. Of all hemodynamic questions, 90% can be
answered by examining data collected in this way. As with most brief
techniques, it is not all inclusive; different hemodynamic measurements for specific clinical situations are necessary. Specific examples
are illustrated later.
The collection of routine hemodynamic data obtained from the
right and left sides of the heart, with appropriate sampling of blood
for oxygen saturations and CO measurements, can be accomplished in
less than 30 minutes. Although the Fick CO method is considered to be
more accurate, CO by the thermodilution (TD) technique is the routine.
Depending on the clinical scenario, both methods of CO determination
have their advantages and limitations. Arterial, vena caval, right atrial
(RA), and pulmonary artery (PA) blood for oxygen saturation measurements are collected for intracardiac shunt identification.
Right- and Left-Sided Heart
Catheterization
The protocol used during right-sided heart catheterization is summarized in Box 4-1. Right-sided heart catheterization is performed for
175
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Hemodynamic Data
R
P
S1S2
100 mm Hg
Isovolumetric
contraction
period
A
AV closes
Isovolumetric
relaxation
Systole Diastole
AV
opens
a LVEDP
LV
Ao
LV
40
A
B
Figure 4-1
electrocardiogram (ECG). Scale mark indicates 100 mm Hg. B, LV and
pulmonary capillary wedge (PCW) pressures on a 0- to 40 -mm Hg scale.
A, A wave; AV, atrioventricular; LVEDP, left ventricular end-diastolic pressure;
P, P wave; R, R wave; S1 and S2, first and second heart sounds; V, V wave
corresponding to mitral valve opening and closing; x, “x” descent; y, “y”
descent.
A, Normal lef t ventricular (LV) and aortic (Ao) pressure with
V
x y
Mitral valve closes
A wave
Mitral
valve
opens
PCW
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Hemodynamic Data 177
40
30
RA 0–4
RV 25/5
NORMAL PRESSURES AND O
Ao 95%
PA 75%
97%
RA 75%
LV
RV 75%
95%
LA
SATURATIONS
2
30
PA
25/10
PCW 97%
LV 120/10
Ao 120/80
PCW
7–12
200
Figure 4-2 Normal oxygen saturation, oxygen volume percentage, and
pressure ranges (mm Hg) in heart chambers and great vessels with pressure
tracings in relation to an electrocardiogram (ECG). Ao, Aortic; LV, lef t ventricle; PA, pulmonary artery; PCW, pulmonary capillary wedge; RA, right
atrium; RV, right ventricle.
Box 4 -1 Right-Sided-Heart Catheterization Protocol
Right Atrium
1. Advance catheter to inferior vena cava (IVC).
2. Obtain oxygen saturation sample (1-mL heparinized syringe).*
3. Advance catheter to right atrium (RA).
4. Record phasic and mean pressure (0- to 40-mm Hg scale, 25 -mm/sec
sweep speed).
Perform Inspiratory Maneuvers
1. Advance catheter to right ventricle (RV).
2. Record phasic pressure (0- to 40 -mm Hg scale, 25- mm/sec sweep
speed).
3. Advance catheter to pulmonar y capillary wedge (PCW).
4. Record phasic/mean/phasic pressure (25/10/25-mm/sec sweep
speed).
Pulmonary Ar tery
1. From PCW, let balloon down, pull catheter back for pulmonar y ar tery
(PA) pressure.
2. Record phasic/mean/phasic pressure (25/10/25-mm/sec sweep speed).
3. Obtain oxygen saturation samples for PA and arterial.
Perform Thermodilution Cardiac Output
*Only one to two drops of heparin should be aspirated an d flushed ou t of 1- to
3-mL hep arinized syringes.
specific indications, most commonly in patients with a history of
dyspnea, valvular heart disease, or intracardiac shunts (Box 4-4).
Patients with a history of pulmonary edema that occurred on a previous hospital admission often have only dyspnea with no objective
evidence (e.g., after chest film, echocardiography) of left ventricular
(LV) dysfunction. Dyspnea caused by lung disease cannot be differentiated from that caused by pulmonary hypertension or LV dysfunction. Right-heart catheterization (RHC) is most commonly performed
with a pulmonary artery catheter (PAC), although larger-bore end-hole
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Hemodynamic Data
Box 4 -2 Left-Sided Heart Catheterization Protocol*
Aortic Valve Assessment
1. Match peripheral to central aortic (Ao) pressure. If using pigtail c atheter
inserted through arterial sheath (sheath should be 1 F larger than
catheter). If using double lumen catheter, match two Ao pressures
before crossing valve.
2. Administer heparin (40 U/kg per laboratory routine).
3. Advance catheter across Ao valve.
4. O btain zero left ventricular (LV) pressure.
5. O btain zero sheath/Ao pressure.
6. Record sheath/Ao pressure and LV pressure simultaneously (0- to
200-mm Hg scale).
*Right-sided heart hemodynamic studies often precede left-sided heart studies.
Simultaneous pressures of the left and right sides of the heart provide the most
precise and accurate information.
Box 4 -3 Combined Left- and Right-Heart Hemodynamic
Protocol
1. Perform right-sided- heart catheterization and p osition catheter in
pulmonary capillar y wedge (PCW)
2. Advance lef t-heart catheter to left ventricle (LV)
3. Aortic (Ao) valve assessment: Follow left-sided heart protocol (see
Table 4 -2)
4. Mitral valve assessment: Obtain zero PCW and femoral arterial (FA) and
LV pressures
Record LV vs. PCW (50-mm/sec speed, 0- to 40-mm Hg scale).
Let down balloon or pull back PCW to pulmonary arter y (PA) (40- mm Hg
scale).
Note: If mitral valve gradient is present, 100 -mm/sec sweep.
Measure cardiac output (CO): Thermodilution (TD) outputs × 3.
Obtain arterial oxygen and pulmonary arterial ox ygen (PAO2) saturation
samples.
5. Right-sided heart pull back
Record PCW to PA (40- mm Hg scale).
Record PA to right ventricular (RV) pressure.
To assess constrictive/restrictive physiology, record RV and LV
simultaneously (capture both 0-40 mm Hg and 0-200 mm Hg to
obser ve dynamic RV/LV respiratory changes).
Record RV to RA (0- to 40-mm Hg sc ale).
Left ventriculography usually performed at this point.
6. Postventriculography hemodynamics
Record post ventriculography left ventricular end- diastolic pressure
(LVEDP) (0 - to 40 -mm Hg scale).
Perform LV pull back to aor ta with sheath/Ao pressures displayed (0 - to
200-mm Hg scale).
catheters may be used and provide high-fidelity tracings. First designed
in the 1970s by Swan and Ganz, the PAC is available in sizes ranging
from 5 F to 7 F and contains four ports: distal, proximal, thermistor,
and balloon inflation. Additional ports for right ventricular (RV) pressure measurement, ventricular pacing, or drug infusion are available.
The PAC may be inserted via femoral, subclavian, internal jugular, or
basilic veins. Potential complications associated with RHC are shown
in Box 4-5.
The most common complication of right-sided heart catheterization is arrhythmia resulting from mechanical catheter stimulation of
the right ventricular outflow tract (RVOT), which can lead to ventricular tachycardia (VT), atrioventricular (AV) block or, rarely, right
bundle-branch block. Significant but transient ventricular arrhythmias
occur in 30% to 60% of RHC procedures and are self-limited (not requiring treatment). The arrhythmia is terminated when the catheter is
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Hemodynamic Data 179
Box 4 -4 Indications and Contraindications for
Right-Sided Heart Catheterization
Indications
Differentiation of shock (cardiogenic, distributive, hypovolemic, or
obstructive)
Complications associated with acute myocardial infarction (i.e.,
hypotension, pulmonar y edema, mitral regurgitation, ventricular septal
defect, right ventricular (RV) ischemia, or tamponade)
Heart failure with reduced or preser ved ejection fraction (diagnosis and
management)
Primar y and secondar y pulmonar y hypertension (diagnosis and
management)
Valvular hear t disease
Cardiac tamponade
Intracardiac shunts
Candidacy evaluation for orthotopic hear t transplant ation (OHTx)
Left ventricular (LV) assist device dysfunction
Acute pulmonary embolism
Assessing volume status in renal or hepatic failure
Postoperative monitoring after cardiac surgery
Primar y lung disease
Contraindications (relative)
Prosthetic tricuspid or pulmonic valve
Coagulopathy
Severe thrombocy topenia
Endocardial pacemaker
Ventricular arrhythmias
Left bundle-branch block
Box 4 -5 Potential Complications of Right-Sided Heart
Catheterization
Arrhy thmias (atrial or ventricular)
Cardiac per foration
Pulmonary infarction
Pulmonary arter y (PA) rupture
Air embolism
Endocarditis
Venous thrombosis
Arterial puncture
Pneumothorax
readjusted. Sustained ventricular arrhythmias have been reported,
especially in unstable patients or those with electrolyte imbalance,
acidosis, or concurrent myocardial ischemia. In patients with left
bundle-branch block, a temporary pacemaker may be necessar y if
right bundle-branch block occurs. Clinical trial data do not support
the routine use of PAC in patients with heart failure. No studies have
examined the clinical utility of PAC in acute myocardial infarction or
cardiogenic shock.
Proper catheter positioning is essential for proper waveform interpretation. Upon catheter insertion to 20 to 25 cm, a normal RA pressure tracing includes five components: (1) “a” wave of atrial contraction,
(2) “x” descent illustrating atrial diastole, (3) “c” wave of tricuspid
valve closure, (4) “v” wave of ventricular systole and passive atrial
filling, and (5) “y” descent of passive atrial emptying (remember as
a/x, c, v/y).
Advancing the PAC to 30 to 35 cm yields a RV waveform that can
be identified by an abrupt increase in systolic pressure and a diastolic
pressure that normally approximates the RA pressure. Rotation of the
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catheter through the RVOT and advancing across the pulmonic valve
at 45 to 55 cm results in a PA waveform identified by three hallmark
findings: (1) abrupt increase in diastolic pressure from RV to PA, (2)
development of a small dicrotic notch in the PA tracing, and
(3) alignment of the peak PA systolic pressure within the electrocardiographic T-wave. Further advancement of the PAC results in
occlusion of a secondary or tertiary branch of a PA and generates the
pulmonary capillary wedge pressure (PCWP) waveform, characterized by a and v waves of reflected left atrial (LA) and LV contraction,
respectively.
Hemodynamic Data
Use of Pulmonary Balloon Occlusion
(Wedge) Pressure
The PCWP closely approximates the LA pressure, reflecting the filling
pressure of the LV in the absence of mitral stenosis. PCWP overestimates LA pressure in patients with acute respiratory failure, chronic
obstructive pulmonary disease with pulmonary hypertension, pulmonary veno-occlusive disease (e.g., pulmonary vein [PV] stenosis after
atrial fibrillation [AF] ablation), or LV failure with volume overload
(Fig. 4-3, A). Reported discrepancies between LA pressure and PCWP
may be caused in part by different types of catheters: Balloon-tipped
flotation catheters are soft with small lumens, and trans-septal pressure catheters (e.g., Brockenbrough or Mullins-type sheath) are stiff
with large lumens. In most clinical settings, PCWP is sufficient to
assess LA and LV filling pressure. PCWP may be inaccurate in patients
with mitral valvular disease or mitral valve prostheses. Trans-septal
LA catheterization should be considered in these cases.
Rules for obtaining an accurate PCWP that agrees with LA pres-
sure are as follows:
1. Position the catheters correctly and verify position through wave-
form, oximetry (oxygen saturation >95%), and fluoroscopy. The
wedged position of the catheter is confirmed by an oxygen saturation sample >95%. Note: Obtaining this saturation uncontaminated
by low-saturation PA blood can be challenging because of the
volume of low-saturation blood that must be discarded before
wedge blood is collected. Use of a large-bore catheter and saline
flushing during antegrade movement into the pulmonary capillary
wedge (PCW) position can help with obtaining accurate oxygen
saturation measurements.
2. Confirm that PCWP is not a damped PA pressure by using a precise
a and v waveform timed against the ECG or LV pressure. Use a stiff,
large-bore, end-hole catheter and connect it to the pressure manifold with stiff, short pressure tubing. The system should be thoroughly flushed and bubble free.
3. For mitral valve area (MVA) determinations, correct for the time
delay (i.e., phase shift the PCWP v wave to match the LV down
stroke) in pressure gradient calculations. However, it is important
to note that this time delay does not correct for the damping of the
PCW tracing that occurs due to its distal position relative to the LA.
Fick Principle for Measurement of
Cardiac Output
The Fick principle states that uptake or release of a substance by any
organ is the product of the arteriovenous concentration difference of
the substance and blood flow to that organ. Pulmonary blood flow
(which is equal to systemic blood flow in the absence of an intracardiac shunt) is determined by measuring the arteriovenous difference
of oxygen across the lungs and the uptake of oxygen from room air
by the lungs. CO is calculated as oxygen consumption divided by the
arteriovenous oxygen (AVO
) concentration difference. The AVO2
2
A
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B
Flow
DistalProximal
Sys gradient
Proximal
C
Figure 4 -3 A, Left panel, Left atrium (LA) (by trans -septal access, orange)
with left ventricular (LV) pressure (yellow); right panel, pulmonary capillary
wedge pressure (PCWP) by pulmonary artery catheter (PAC) with LV pressure
showing the higher pulmonar y capillary wedge (PCW)-LV gradient of
16 mm Hg compared with direct LA-LV gradient of 4 mm Hg. For best accu racy in assessing mitral valve gradients, use the trans-septal approach.
B, MCG Diagnostics oximetric mask. C, Diagram of pressure gradient across
a stenosis or narrowing. The pressure gradient is the difference between
proximal and distal pressure. Pressure distal to the narrowing shows a
systolic and diastolic pressure gradient. (Figure 4-3, B, Cour tesy MCG
Diagnostics.)
Distal
Distal
Diastolic gradient
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