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Coronary Angiography and Ventriculography 163
A
Figure 3-48 Image magnification. A, When a hand is held close to the
surface on which the shadow falls, the image is sharp.
(Continued)
Imaging Equipment Preventive Maintenance
The x-ray unit should be placed on a program of scheduled preventive maintenance that is performed by trained service technicians.
This maintenance should be done at least biannually, with quarterly
checks preferred. Maintenance and cleaning schedules should be
monitored by the staff so that equipment can be scheduled for routine
maintenance.
Digital Angiography Archives
The x-ray image is converted into a quantitative digital format for
storage and display on a computer. Archival storage uses magnetic
tapes, disks, or other electronic media and permits compact storage,
image enhancement, and retrieval for quantitative image analysis.
Radiation Safety
Radiation protection equipment must be available for all personnel in
every cardiac catheterization laboratory. Standards for radiation pro tection have been published by the Society of Cardiac Angiography and Interventions, ACC, and American Heart Association (AHA).
Four principles of radiation safety should be self-evident:
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Coronary Angiography and Ventriculography
B
Figure 3- 48, cont’d
larger and “fuzzier” the image becomes.
1. The less the exposure, the less the chance of absorbed energy
biologic interaction.
2. No known level of ionizing radiation is a permissible dose or absolutely safe.
3. Radiation exposure is cumulative. No washout phenomenon
occurs.
4. All participants in the cardiac catheterization laboratory have
voluntarily accepted some degree of radiation exposure but are
obligated to minimize and reduce risks to other personnel and
themselves.
The source of radiation in the cardiac catheterization laboratory
is the primary x-ray beam that emanates from the under table tube,
upward and outward toward the II. Scatter of this beam (mostly
because of transit through the patient) exposes all subjects to radiation in a dose geometrically inverse to the distance from the source.
Radiation scatter is increased when the angle of the tube is set
obliquely. A high degree of angulation with large obliquities increases
the amount of radiation scatter. Acrylic lead shields and table-mounted
lead aprons should be used to reduce the amount of scatter.
Fluoroscopy generates x-ray exposure approximately one-fifth
that of cineangiography. The increased use of cineangiography for
complex catheterization procedures increases the total radiation
exposure in the laboratory and should be a consideration in proce-
B, The farther the hand moves from this surface, the
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Coronary Angiography and Ventriculography 165
I
X
I
X
C
Figure 3- 48, cont’d
wall and the heart, the image obtained is sharp. D, When the hear t lies
farther from the II and closer to the x-ray source (X), the image is magnified but poorly defined and hazy. Increased x-ray source-to-image dis tances require more kilovoltage, also degrading the image. (From King SB,
Douglas JS Jr: Coronary angiography and angioplasty, New York, 1985,
McGraw-Hill.)
C, When the image intensifier (I) is close to the chest
D
dures requiring extensive intracardiac manipulation, such as PCI, electrophysiologic (EP) studies, or valvuloplasty.
Personal Radiation Protection
Radiation protection for laboratory personnel should include eye,
neck, and body shielding. Physicians performing cardiac angiography
should be protected by room-installed radiation shields. Exposure
with a shield resulting from performing 25 examinations per week on
a continuous basis should be within the recommendations of the
National Commission on Radiologic Protection and Units.
Radiation exposure is greater during PCI than during diagnostic
catheterization. If protective shields are used carefully, radiation expo sure may be comparable for single- and double-vessel angioplasty
procedures and for diagnostic catheterization procedures. Radiation
exposure is higher for diagnostic and angioplasty procedures using
biplane imaging.
During angiographic studies, 90% of the x-ray energy entering the
body is absorbed. It has been shown that a single exposure of 200 R
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Entrance skin dose
5 mR/h
B
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Coronary Angiography and Ventriculography
400
4.4 x dose
at 23 cm
300
200
(arb. units)
100
0
Normal
(23 cm)
Figure 3-49
radiation dose increases by the square of the ratio of image intensifier (II)
diameter. arb, Arbitrary; Mag, magnification.
The effect of electronic magnification on entry skin dose. The
180
z
160
140
120
100
cm
80
60
40
20
2.4 x dose
at 23 cm
Mag 1
(15 cm)
50 mR/h
Mag 2
(11 cm)
10 mR/h
20 mR/h
90 kV
1 mA
= +30°
y = 0
x
A
cm
Figure 3-50 Effect of angulation on radiation scatter.
180
160
140
120
100
80
60
40
z
10 mR/h
cm
20mR/h
cm
5 mR/h
0255075100125
90 kV
1 mA
= −30°
y = 0
50 mR/h
x
0255075100125
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Coronary Angiography and Ventriculography 167
A
B
Figure 3-51 A to C, Foreshortening of the shadow of an object is not paral-
lel with the filming plane.
can produce cataract formation in humans. Thyroid cancers and other
carcinomas are associated with x-rays. Techniques often used to
improve image quality (e.g., increased amperage, voltage, LAO views)
have resulted in increased exposure. A summary of radiation safety
for the cardiac catheterization laboratory is provided in Box 3-4 (also
discussed in Chapter 1).
C
(Continued)
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Coronary Angiography and Ventriculography
D
Figure 3-51, cont’d
tor must use a view perpendicular to the longitudinal axis of the vessel but
parallel to the longest diameter of the lesion. (From Pujadas G: Coronary
angiography in the medical and surgical treatment of ischemic heart disease,
New York, 1980, McGraw-Hill.)
D, To evaluate a slit-like lesion accurately, the opera-
Box 3-4 Radiation Safety Considerations During Cardiac
Catheterization
Radiation to Patient
1. Originates from the primary x-ray beam and then scatters on passing
through the body
2. Affects thyroid, eyes, gonads, bone marrow, or gastrointestinal tract
3. Highest exposure of any diagnostic test
Radiation to Staff
1. Long-term low dose from scatter and tube leakage
2. Affects thyroid and eyes
3. Accepted occupational exposure
Means of Limiting Dose
1. Maintain equipment safeguards
2. Optimize milliamperage and kilovoltage
3. Minimize exposure time
4. Minimize scatter with shielding and techniques
5. For staff, maximize distance from source
6. Use all protective measures
Angiographic Equipment
Injectors and Contrast Materials
The angiographic power injector allows the angiographer to administer a precise volume (bolus) of contrast material at a rapid, preset flow
rate. Power injectors are necessary for performing ventricular and
great vessel angiography. The injector uses a large syringe for radiographic contrast media. Power injector settings are selected, and on
receiving an electronic signal, a calibrated motor discharges the exact
amount of contrast material at the predetermined rate through a connecting tube and catheter to the patient. The quantity and type of
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contrast material (concentration or dilution) and rate of injection are
operator or physician selected. The signal to the injector to inject the
contrast media is transmitted from a hand- or foot-operated switch.
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Coronary Angiography and Ventriculography 169
Power Contrast Injector: Responsibilities of
the Nurse or Technician
1. For an off-table freestanding injector, the nurse or technician loads
the syringe with contrast media.
2. The nurse or technician sets the volume, flow rate, and rate of pressure rise parameters as instructed by the physician.
3. The nurse or technician presses the inject button that triggers the
injection. Releasing the button stops the injection.
The staff member and physicians must be aware of the following
points regarding safe power injection. Some injector systems (e.g.,
ACIST) have physician-operated touch-sensitive injection controls on
the table.
Be sure to clear air bubbles. All air must be expelled from the
contrast-filled syringe before making the injector available to the physician for the catheter connection. Under no circumstances should the
head of the power injector be tilted toward the catheterization table
or made available for the physician if air is in the syringe.
Several techniques are used to establish a bubble-free system
when connecting the catheter to the syringe. A running connection is
a technique in which a small amount of contrast material is squirted
out of the syringe while the catheter is being connected to the syringe.
Merging of the fluid streams of blood from the catheter and the forward
flow of contrast material from the syringe prevents any large air
bubbles from entering the system on connection. After connection,
the injector operator always aspirates more fluid (usually contrast
material in the connector tube) into the syringe to ensure that no air
bubbles are present. If air is present, it is expelled, and the clearing
procedure is redone.
The operator must be careful when aspirating blood into the
contrast syringe for two reasons: (1) A large blood volume in the
syringe dilutes the contrast material, and (2) more important, but
rarely, after some time the blood may clot in the injector syringe.
Variable rate automatic injectors operated from the sterile table
have air bubble detectors that prohibit injection if air is detected anywhere in the injection pathway.
Test Injection in Ventricle
When the system is free of air, the injector operator and physician
should be sure that the catheter is cleared of blood. The injector operator squirts a small amount of contrast material out of the tip of the
catheter under x-ray visualization. This small test injection of contrast
material also helps the physician ascertain proper catheter position
for ventriculography.
Confirming Injector Settings
The physician should orally confirm the power injector settings for the
contrast volume and delivery rate desired. The injector operator
should repeat the injection parameters back to the physician to eliminate any chance of error in injector setup. Before injecting, the staff
member must ensure that the catheter being used can accept the flow
rate that has been entered into the injector.
Safety Features
When the physician has initiated a cineangiographic run, the injector
operator must listen for the physician’s command to start the injection.
The nurse or technician should be prepared to stop the injection (by
hitting or releasing the trigger button) at any time as directed by the
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physician or at his or her own discretion (e.g., when the catheter is
pulled back or a contrast stain in the heart muscle is seen).
and injections for small bubbles or other problems. Six (or more) eyes
are better than four for seeing catheterization laboratory problems.
Power injectors have many safety features that must be understood by
the cardiac catheterization laboratory staff. To ensure patient safety
during angiography, staff members must understand all aspects of the
operation of the power injector and built-in safeguards.
Coronary Angiography and Ventriculography
Note: All personnel should be watching the power injection setup
Contrast Media
During angiography, the catheterization laboratory staff provides technical support with regard to contrast media in the following areas:
1. Contrast agents should be warmed to body temperature before
administration. Commercial warmers are available from companies that manufacture contrast media.
2. The nurse or technician preparing the patient for angiography
should ask the patient if he or she is aware of any known contrast
allergy. Iodine gives contrast material its radiopaque qualities and
is a known allergen. Although some believe that a history of seafood
allergy (iodine is found in certain seafood, especially shellfish) is
significant, this does not appear to be the case. Nonetheless, the
physician should be notified of patient seafood allergy. The physician may wish to give corticosteroids or antihistamines to these
patients before performing angiography (see Chapter 1).
3. Before the administration of contrast agents, the patient should be
told about the sensations associated with contrast administration.
Rarely, patients have nausea and vomiting, so patients should not
have ingested food or water before angiography. If vomiting occurs,
staff members should be quick to respond; patients’ heads should
be turned to the side (away from the sterile field) to prevent aspiration. This is particularly important when patients have been heavily
sedated for the procedure.
4. Patients should be told that they may feel a hot flushing sensation
(caused by artery vasodilation) during the LV injections of contrast
media. Direct injection of contrast material into peripheral vessels
may produce a painful burning and cramping sensation. These
reactions are uncommon with the nonionic, low-osmolar agents
that are used today.
During angiography, it is important for the nurse to document the
type and amount of contrast material delivered and any signs of
allergy, such as hives, flushed skin, bronchospasm, or laryngeal edema
(hoarseness). Appropriate medications for treatment of anaphylaxis,
such as epinephrine, and an airway should always be easily accessible
during the procedure.
Although uncommon with nonionic low-osmolar contrast media
(LOCM), hypotension, bradycardia, and arrhythmias have been
reported during injections. Therefore, the ECG and arterial pressure
should be monitored continuously. Atropine, vasopressors, and antiarrhythmic agents should be available for prompt administration. Transient bradycardia or hypotension can be overcome with a brief forceful
cough. Use of nonionic low-osmolality contrast agents has greatly
reduced the incidence of bradycardia, arrhythmias, hypotension, and
the need for coughing during coronary angiography.
After angiography and before discharge, the patient should
receive 500 to 1000 mL of normal saline IV over 4 to 6 hours.
Selection of Radiographic Contrast Media
The contrast material is selected for the specific examination to be
conducted. All contrast agents contain iodine, an effective absorber
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Coronary Angiography and Ventriculography 171
of x-rays, which makes iodine-filled structures x-ray “dense” when
compared with other body structures. Those tissues without iodinated
material are more x-ray “lucent” and absorb x-rays to provide different
gray shades in x-ray images. The quantity and concentration of contrast materials used are specific medical decisions. Factors included
in these decisions are the patient’s age, size, general health, allergies,
and cardiac condition.
Although all agents are derivatives of benzoic acid, the number
of iodine molecules and ionic and osmolar composition vary (Table
3-5). Osmolality, viscosity, sodium content, and other additives and
properties are different among these agents. Table 3-6 summarizes
commonly used contrast agents for coronar y and LV angiographic
studies. Selection of a contrast agent for the particular laboratory is,
to a large extent, a matter of personal preference. Major differences
between ionic and nonionic contrast agents include cost, effect of
hemodynamics, and LV and renal function. Historically, ionic contrast
media produced hypotension by peripheral arterial vasodilation, transient myocardial dysfunction, and decrease in circulating volume and
blood pressure after osmotic diuresis (initially contrast media increase
circulating fluid volume by osmotically shifting fluid into the vascular
space).
Table 3 -5
Classification and Distinguishing Properties of Various
Contrast Agents
Quality High Low Low Iso- Osmolar
Osmolality
Ionicit y Ionic Ionic Nonionic Nonionic
Number of
benzene rings
Name Diatrizoate
Viscosity Low Low Intermediate High
Ratio (iodine/
osmotically
active par ticles
From Klein L, Sheldon MW, Brinker J, et al: The use of radiographic contrast media
during PCI: a fo cused review: a p osition statement of the Society of Cardiovasc ular
Angiography and Inter ventions. Catheter Cardiovasc Intervent 74:728–746, 2009.
>1500
Monomer Dimer Monomer Dimer
Iothalamate
1.5 3 3 6
600 600 –1000 280
Ioxaglate
Iopamidol
Ioversol
Iopromide
Iomeprol
Iohexol Iodixanol
Table 3 -6
Contrast Agents in the Catheterization Laboratory
Contrast Type Chemical Name Trade Name Manufacturer
High-osmolar ionic Diatrizoate Renografin Bracco
Low- osmolar nonionic Iopamidol Isovue Bracco
Low- osmolar ionic dimer Ioxaglate Hexabrix Mallinckrodt
Iso- osmolar nonionic
dimer
From Klein L, Sheldon MW, Brinker J, et al: The use of radiographic contrast media
during PCI: a fo cused review: a p osition statement of the Society of Cardiovasc ular
Angiography and Inter ventions. Catheter Cardiovasc Intervent 74:728–746, 2009.
Diatrozoate Hypaque GE Health Care
Iothalamate Conray Mallinckrodt
Metrizoate Isopaque Sanofi
Iohexol Omnipaque Amersham
Ioversol Optiray Mallinckrodt
Ioxilan Oxilan Guerbet
Iodixanol Visipaque Amersham
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Coronary Angiography and Ventriculography
Nonionic LOCM have been shown to be safer than ionic, highosmolar agents. LOCM are routinely used in all catheterization laboratories around the world and produce satisfactory diagnostic imaging
quality, especially for high-risk patients. Despite numerous studies and
meta-analyses, there is no consensus on which of the LOCM is superior
with regard to contrast-induced renal injury or nephropathy.
Contrast-Induced Renal Injury
or Nephropathy
Contrast-induced nephropathy (CIN) is related to underlying renal
function. Risk factors for CIN are summarized in Table 3-7. Serum
creatinine level is a crude indicator of true glomerular filtration rate
(GFR), whereas creatinine clearance (CrCl), calculated using the
Cockcroft-Gault formula, has been repeatedly ben shown to be a more
reliable indicator of GFR.
Recommendations to Prevent ContrastInduced Nephropathy Based on Glomerular
Filtration Rate
1. GFR or CrCl greater than 60 mL/min
a. Hold Metformin until 48 hours postprocedure.
2. GFR or CrCl 30 to 60 mL/min
a. Hydrate the night before the procedure with at least four to six
glasses of water up to 4 hours preprocedure.
b. Hold angiotensin-converting enzyme (ACE) inhibitors, angioten-
sin receptor blockers, diuretics, nonsteroidal antiinflammatory
Table 3 -7
Risk Factors for Contrast-Induced Nephropathy*
Patient Related Extrinsic Possible
PRI Volume of contrast Metabolic syndrome
CHF High-osmolal contrast Diabetes
Diabetes mellitus with PRI Intraaor tic balloon Prediabetes
Age >70 years
Volume depletion MCA within 72 hours ACE- I/ARB
Hypotension Urgent/emergent PCI Female gender
Anemia Multiple myeloma
Hypertension Cirrhosis
PVD Intraar terial contrast
Modified from Best PJ, Ber ger PB, Davis BR, et al: Impact of mild or m oderate
chronic kidn ey disease on the frequency of restenosis: Result s fro m the PRESTO
trial. J Am Coll Cardiol 44:1786–1791, 2004; P arfrey P: The clinical epidemiology of
contrast-induced nephropathy, Cardiovas c Intervent Radiol 28(suppl 2):S3 –S11,
2005; McCullough PA, Adam A, Becker CR, et al: Epidemiolog y and prognostic
implications of contrast-induc ed nephropathy, Am J Cardiol 98(suppl):5K–13K,
2006; and Weinrauch LA, Healy RW, Leland OS, et al: Coron ary angiog raphy and
acute renal failure in diabetic azotemic nephropathy. Ann Intern Med 86:56–59,
1977.
ACE-I, Angiotensin -converting enzyme inhibitor; ARB, angiotensin II recepto r blocker;
CHF, congestive hear t f ailure; GFR, glomerular filt ration rate; MCA, multiple contrast
administration; PCI, percutane ous coronar y intervention; PRI, pr eexistent renal
insuf ficiency; PVD, per ipheral vascular disease.
*Bolded factors contribute to risk scores of Mehran, et al., and/or Bart holomew,
et al. (Mehr an R, Aymong ED, Nikolsky E, et al: A simple risk score for prediction of
contrast-induced nephropathy after percutaneous coronar y intervention:
Develop ment and initial validation. J Am Coll Cardiol 44:1393–1399, 20 04;
Bartholomew BA, Harjai K J, Duk kipati S, et al: Impact of nephropathy after
percutaneous coronary inter vention and a method for r isk stratification. Am J
Cardiol 93:1515–1519, 2004).
Nephrotoxic drugs Hyp eruricemia
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