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Interventional Cardiology Procedures
require retreatment or CABG. Restenosis is caused mostly by intimal
hyperplasia and rarely by vessel recoil after stenting. Typically, restenosis occurs during the initial 6 months after PCI. The in-stent restenosis rate is <10% with drug-eluting stents. Stent thrombosis is the abrupt
formation of a blood clot inside the stent, which is potentially catastrophic and can lead to myocardial infarction (MI) or death. The
incidence of stent thrombosis is 1% to 2%. It is more likely to occur if
dual antiplatelet therapy (i.e., aspirin and clopidogrel or other P2Y
platelet inhibitors) is prematurely discontinued or the stent is suboptimally expanded.
The indications, contraindications, and complications of PCI are
listed in Box 10-1.
Equipment
PCI equipment consists of three basic elements: guiding catheter,
balloon-stent catheter, and coronary guidewire (Fig. 10-2).
Box 10 -1 Indications, Contraindications, and Complications
of Percutaneous Coronary Intervention
Indications for Percutaneous Coronary Intervention
Angina pectoris causing sufficient symptoms despite optimal medical therapy
Mild angina pectoris with objective evidence of ischemia (by abnormal
stress testing or physiology) and high- grade lesion (>70% diameter
narrowing) of a vessel supplying a large area of myocardium
Unstable angina or NSTEMI
STEMI as primary therapy or in patients who have persistent or recurrent
ischemia after failed thrombolytic therapy
Angina pectoris after CABG
Restenosis af ter successful PCI
LV dysfunction with objective evidence of viability of a vessel supplying the
myocardium
Arrhy thmia secondary to ischemia
Contraindications for Percutaneous Coronary Intervention*
Unsuitable coronar y anatomy
Extremely high-risk coronary anatomy in which closure of vessel would
result in patient death
Contraindication to CABG (however, some patients have PCI as their only
alternative to revascularization)
Bleeding diathesis
Patient noncompliance with dual antiplatelet therapy and unwillingness to
follow post- PCI instructions
Multiple in-stent restenosis
Patients who cannot give informed consent
Complications Associated with Percutaneous Coronary Intervention
Death (<1%)
MI (<3% to 5%)
Stent thrombosis (~1%)
Emergency CABG (<1%)
Abrupt vessel closure (0.8%)
Coronary arter y perforation (<1%)
All complications that can occur during cardiac catheterization, including
access site bleeding, pseudoaneurysm, AV fistula, ischemic vascular
complications, stroke, allergic reaction to contrast media, and renal failure
12
AV, Atrioventricular; C ABG, coronar y arter y bypass graft; LV, lef t ventricular;
MI, myocardial inf arction; NSTEMI, non -ST segment elevation myocardial infarction;
PCI, percu taneous coronary inter vention; STEMI , ST-segment elevation myocardial
infarction.
*If PCI is the only life sav ing procedure, risk versus benefit is weig hed and the
contraindication b ecome relative to the clinical situation.
Saline
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Interventional Cardiology Procedures 423
Guiding catheter
Figure 10 -2
Arterial
pressure
monitoring
Arterial
sheath
Balloon
Y adapter
Coronary
guidewire
Components of percutaneous coronary intervention (PCI)
Contrast
Balloon
catheter
Steering
tool
Waste
Four-way
manifold
Inflation
device
equipment. (From Freed M, Grines C, Safian RD: The new manual of interventional cardiology, Birmingham, MI, 1996, Physicians’ Press.)
1
2
6
3
5
4
Figure 10-3 Illustration of a guiding catheter. 1, Stiffer body; 2, variable
softer primary curve; 3, wire braiding; 4, atraumatic tip; 5, large lumen
(optional radiopaque marker); 6, lubricous coating. (Courtesy of Boston
Scientific Corporation, Boston, MA.)
Guiding Catheter
A special large-lumen catheter is used to guide the coronar y balloon
catheter to the vessel that has the lesion to be dilated (Fig. 10-3).
Compared with a diagnostic catheter, a guiding catheter has a thinner
wall and larger lumen, which allows contrast injections while the
balloon catheter is in place. A guiding catheter is stiffer than a diagnostic catheter to provide support for advancing the balloon-stent
catheters into the coronary artery. It responds differently to manipulation than a diagnostic catheter. The guiding catheter tip is not tapered,
occasionally blocking the ostium and causing pressure dampening
while engaging the coronary ostium. A 6-F guiding catheter is generally used. Some catheters have relatively shorter and more flexible
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tips than others, theoretically to decrease catheter-induced trauma.
Others may have side holes to help maintain blood flow during PCI.
Larger guiding catheters (7 F or 8 F) may be necessary for kissing
balloons/stents, rotablator burrs >2 mm, and some cutting balloons.
The guiding catheter comes in many different shapes for femoral and
radial approaches. Guide catheters are shaped for specific anatomic
variations.
Interventional Cardiology Procedures
Functions of the Guiding Catheter
The three major functions of a guiding catheter during PCI include:
1. Balloon-stent catheter delivery: The guiding catheter is the delivery
device of the balloon catheter to the coronary artery. If the guiding
catheter is not seated properly in a coaxial manner, it may not be
possible to advance the balloon stent across the stenotic area. The
guiding catheter seats in the coronar y artery (cannulation) and
provides the necessary backup support or “platform” to push the
balloon/stent catheter across the stenosis.
Several terms that are commonly used when referring to
guiding catheters are important:
•
Backing out: The guiding catheter is ejected from the coronar y
ostium into the aortic root when pressure is applied to the
balloon in an attempt to cross the lesion. This is caused by an
insufficient support position or a tight stenosis.
•
Strong backup: A stable support position of the guiding catheter
at the orifice of the coronar y ostium provides the necessar y
platform to advance the balloon across the lesion.
•
Deep seating: The guiding catheter is manipulated over the
balloon catheter shaft past the ostium and further into the
vessel to increase backup support for crossing difficult lesions.
This maneuver is typically used as a last resort because of the
increased risk of guiding catheter–induced dissection of the
proximal vessel.
2. Contrast injection: The guiding catheter permits visualization of the
target by contrast administration with or without the balloon catheter in place. Some large PCI devices may block adequate contrast
3. Pressure monitoring: The guiding catheter lumen measures aortic
pressure for determination of the trans-stenotic pressure gradient
for physiologic lesion assessment, ostial lesions (pressure wave
damping), and hypotension during prolonged ischemia.
Balloon Angioplasty and Stent
Delivery Catheters
Technologic refinements of balloon catheters have dramatically
improved the success rate of PCI. There are two principal types of
balloon-stent catheters: (1) over the wire (OTW) angioplasty PCI
systems and (2) rapid-exchange (RX; monorail) PCI catheters.
Over the Wire Angioplasty Percutaneous Coronary
Intervention Systems
An OTW angioplasty PCI catheter (Fig. 10-4) has a central lumen
throughout the length of the catheter for the guidewire and a separate
lumen for balloon inflation. This catheter is approximately 145 to
155 cm long and can be used with a long or short guidewire, usually
0.014 inch.
This catheter can accept multiple guidewires, which allows for
exchanging of additional devices that may require stronger, stiffer
guidewires. Maintenance of distal wire position beyond the target
stenosis is paramount in coronary angioplasty. For an OTW balloon
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Interventional Cardiology Procedures 425
Radiopaque
marker
band
Guidewire
lumen
Figure 10-4 Schematic design of a typical over the wire (OTW) angioplasty
balloon catheter. The guidewire extends the entire length of the catheter.
Figure 10-5 Schematic design of a typical rapid-exchange (RX) angioplasty
balloon catheter. The guidewire extends on “through” the distal part of the
catheter, allowing for single-operator use. (Courtesy of Boston Scientific
Corporation, Boston, MA.)
Inner and
outer
coatings
2.5-F
distal shaft
Protective
strain relief
2
Inflation
lumen
1
3
5
Guidewire
lumen
4
catheter, the guidewire can be extended to help maintain distal position while the balloon catheter is withdrawn completely over the
guidewire to permit another balloon catheter to be exchanged and
introduced over the same guidewire for additional dilations. A 300-cm
exchange wire is commonly used.
One disadvantage of an OTW angioplasty balloon catheter is that
a primar y operator and an experienced assistant are required to
perform catheter exchanges. A technique to make balloon catheter
exchanges easier involves a balloon inside of the guide catheter
inflated to fix a 155-cm guidewire in place, which permits OTW catheters to be exchanged without using a 300-cm guidewire.
Rapid-Exchange (Monorail) Percutaneous Coronary
Intervention Catheter
A RX balloon catheter is the most popular catheter used today and
allows a single operator to exchange PCI catheters unassisted. It differs
from OTW PCI catheters in that only a variable length of the shaft has
two lumens (Fig. 10-5). One lumen is for balloon inflation and the
other, which extends through only a portion of the catheter shaft,
houses the guidewire. Because only a limited portion of the balloon
requires dual lumens, the catheter shafts can be made smaller than
OTW systems.
An RX balloon catheter addresses certain inherent limitations of
the OTW system: It eliminates the need for a long exchange guidewire
and permits an operator to maintain distal guidewire position without
the aid of an assistant.
Limitations of a monorail catheter include the need for excellent
guiding catheter support and more operator skill for the complexity in
manipulating the guidewire, balloon catheter, and guiding catheter.
Blood loss during removal of the monorail balloon catheter at the
rotating hemostatic valve can be a problem but can be reduced with
better technique and attention to the “Y” connectors.
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Table 10 -3
Interventional Cardiology Procedures
Advantages and Limitations of Angioplasty Balloon
Catheter Types
Type Advantages Limitations
Over the wire
(OTW)
Rapid
exchange
(RX;
monorail)
•
Distal wire position
• Accepts multiple wires;
distal por t for pressure,
contrast injection
Ease of use; single-
•
operator system
• Enhanced visualization
• Needs two people for
exchanging balloon
catheter/stent
• Needs good guide support
• Blood loss at Y valve
during exchanges; inability
to change wire
The advantages and limitations of OTW and RX balloon catheters
are listed in Table 10-3.
Procedural Details for Percutaneous
Coronary Intervention
After crossing the lesion with the balloon catheter, the balloon is
inflated and deflated using a hand-held syringe device with a pressure
gauge. Balloon catheter sizes range from 1.5 to 5 mm in diameter (size
of the inflated balloon) for coronary arteries and are larger for peripheral arteries. Balloon diameter is selected according to the angiographic size of the vessel to be dilated. The plastic materials of balloon
catheter construction determine the flexibility of the catheter shaft and
balloon characteristics (e.g., burst pressure and actual diameter under
different pressure levels). Special-purpose coronary balloon catheters
are available for specific types of lesions. A noncompliant high-pressure
balloon is commonly used to optimize stent implantation results to
achieve full stent expansion and strut apposition. Balloon lengths vary
from 10 to 38 mm in length. A cutting balloon is a special balloon
catheter with three to four atherotomes (or blades) that run longitudinally on the balloon to score the lesion in a more controlled fashion.
Angioplasty Guidewires
Coronary angioplasty guidewires are small-caliber (0.010- to 0.014-inch
diameters) steerable wires that are typically 160 cm long. They are
advanced into the coronary artery or branches beyond the lesion to
be dilated. The flexible tip may be shaped by the operator to negotiate
side branches and tortuous artery curves. The balloon-stent catheter
is advanced over the wire and, after artery dilation, removed from the
artery with the wire remaining in place beyond the dilated lesion.
Extra-long guidewires (300 cm) are used to exchange OTW balloon
catheters. Tip flexibility and torque control characteristics of these
coronary guidewires vary. Generally, the softer wires are safer and
easier to advance into tortuous branches, whereas the stiffer wires give
better torque control and may be useful for crossing difficult or total
occlusions. Hydrophilic wires, which have special coatings to cross
subtotally or totally occluded stenoses better, generally carry a higher
risk of perforation if the tip position is not kept in the major vessel
lumen and dissection if the guidewire is advanced under an intimal
flap.
Exchange and Extension Guidewires
An exchange guidewire is similar to the standard 180 cm guidewire
mentioned previously except that its length is 280 to 300 cm. This long
wire replaces the initial wire when the exchange of an OTW balloon
catheter is necessary. Alternatively a 120- to 145-cm extension wire can
be connected to the end of the initial guidewire to allow balloon
catheter exchanges.
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Interventional Cardiology Procedures 427
Other Equipment
Y Connector (Adjustable Hemostasis Device)
The Y connector, which comes with a rotating or spring-controlled
valve, is an accessor y device that minimizes back-bleeding while the
balloon/stent catheter is inserted into and removed from the guiding
catheter. This device allows the injection of contrast media and pressure monitoring through the guiding catheter, regardless of balloon
catheter position.
Inflation Device
A disposable syringe device is used to inflate the balloon on the
balloon catheter with precise measurement of the inflation pressure
in atmospheres, generally ranging from 4 to 20 atm. Although stents
may be inflated at 10 to 18 atm, the balloon is typically inflated with
sufficient pressure to compress the plaque caused by stenosis and fully
expand the “dumbbell,” or indentation, at the waist of the partially
inflated balloon. Occasionally, hard, resistant stenoses (calcium or
fibrosis) may require high pressures (>
indentation. Needless balloon overinflation increases the risk of coronary dissection and perforation.
Torque (Tool) Device
A small cylindrical pin vise clamp slides over the proximal end of the
angioplasty guidewire, permitting the operator to perform fine manipulations of the guidewire by turning the torque tool in a clockwise or
counterclockwise direction. Figure 10-6 shows examples of the inflation device, Y connectors, guidewire introducers, and torque tool.
14 atm) to expand the dumbbell
Clinical Procedure
The clinical procedure for PCI is as follows:
I. Clinical and angiographic indications for proceeding with PCI
should be confirmed. Noninvasive testing for ischemia is recommended in patients with atypical anginal symptoms or chest pain
syndrome without evidence of clinical ischemia. Before PCI,
the following procedures can be performed to obtain objective
evidence of ischemia: electrocardiogram (ECG) (for evidence of
1
3
4
2
Figure 10-6 Examples of balloon inflation device and Y connectors, wire
introducer needles, and torque tool. (Reprinted with permission from Meritt
Medical Systems, Inc. All rights reserved.)
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II. Pre-PCI preparation
III. Patient preparation in catheterization suite
IV. Guiding coronar y angiograms (after 100 to 200 µg of nitro-
Interventional Cardiology Procedures
resting ischemia or recent infarction); stress perfusion imaging
or stress echocardiography (either exercise or pharmacologic);
or for lesions of uncertain significance, in-laboratory translesional physiology assessment (with the use of fractional flow
reserve [FFR]).
1. Patient preparation should include placement of ECG electrodes, pacer/defibrillator pads, and intravenous (IV) line.
Make sure you have a list of the patient’s current medications
and a signed informed consent form.
2. Perform patient and family teaching, including explaining
the procedure, anticipated results, and potential for
complications.
3. Give cardiothoracic surgery consultation for high-risk patients
and those with multivessel disease (especially patients with
diabetes), left main disease, or left ventricular (LV)
dysfunction.
4. Do a laboratory blood work check, including complete blood
cell and platelet counts, international normalized ratio (INR),
partial thromboplastin time (PTT), electrolytes, blood urea
nitrogen, and creatinine.
1. ECG (inferior and anterior wall leads): Use ECG with 12 leads
(radiolucent).
2. Skin preparation: Prepare inguinal area for femoral artery or
wrist for radial artery.
3. Consider femoral venous access for high-risk patients or those
with acute MI, rotablator, or thrombus aspiration device. Most
PCI procedures can also be performed from the radial
approach, with lower bleeding risk obviating the need for a
vascular closure device (VCD). Venous access for temporary
pacing is no longer routine.
4. Antiplatelet therapy: Aspirin (325 mg orally). Failure to administer aspirin before PCI is associated with a two to three times
higher acute complication rate, including acute MI and stent
thrombosis. Clopidogrel (600 mg orally) or other P2Y12 platelet
inhibitors, such as prasugrel or ticagrelor, if patient presents
with acute coronary syndrome (ACS); routinely given before
or immediately after PCI.
5. Anticoagulation: Heparin (70- to 100-µg/kg bolus or lower if
glycoprotein [GP] IIb/IIIa blocker is used) with a target activated clotting time (ACT) >
native to heparin, with reports of lower bleeding risk in some
patients.
6. Consider GP IIb/IIIa blockers in patients with complicated procedures associated with thrombus or MI with large thrombotic
burden.
7. Give Versed (1 mg IV) and Fentanyl (25 to 100 µg IV) for
sedation.
8. For patients allergic to contrast media, give prednisone (60 mg,
13 hours, 7 hours, and 1 hour before cardiac catheterization).
Diphenhydramine (25 to 50 mg IV or orally) and H2 blockers
are used in some centers.
glycerin IC)
1. Define coronary anatomy and collateral supply (if any).
2. Store guiding shots to use as reference “roadmap” for balloonstent positioning.
3. Select device size as judged from known guide catheter diameter to select the balloon-stent diameter.
Note:
8 F = 2.87 mm, 6 F = 2 mm (size of PCI device based
on distal artery normal reference segment; balloon/
artery ratio <
1 : 1.2)
250 seconds. Bivalirudin is an alter-
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V. PCI procedure
1. Select guiding catheter for angle of vessel takeoff and optimal
backup support.
2. Ensure the guiding catheter is seated; coaxial alignment is best.
3. Advance guidewire beyond target stenosis to distal position in
the vessel.
4. Insert balloon catheter through hemostasis Y valve on guiding
catheter and advance into the stenosis, centering the balloon
using radiopaque markers on balloon catheter.
5. Inflate balloon to fully expand and remove dumbbell indentation of lesion on underinflated balloon. Balloons as well as
stents may be inflated for 10 to 30 seconds or longer, as tolerated. Then, deflate the balloon.
6. Exchange the balloon catheter for the stent catheter and
repeat the process. Using a balloon first opens the vessel,
providing pressure and flow to the distal vessel segment. This
often enlarges the size of the vessel, possibly changing initial
thinking regarding the best stent size.
7. Determine final result after intravascular ultrasound (IVUS)
and optical coherence tomography (OCT) with or without
high-pressure noncompliant balloon for optimal stent
implantation.
VI. Assessment of PCI result
1. Check for enlarged artery lumen (<10% residual lesion) and
good angiographic flow (thrombolysis in MI [TIMI] grade 3).
2. Full stent apposition is based on angiogram and/or IVUS.
3. Check for absence of adverse angiographic complications
(e.g., thrombus, dissection, or perforation).
4. Make sure there is no residual ischemia (ECG changes with or
without chest pain).
VII. Considerations for additional stenting
1. New lesion proximal or distal to stent (i.e., edge dissection)
may require additional stenting.
2. Large dissection extending in either direction may require
additional stenting.
3. Slow flow may require FFR or IVUS to establish cause (i.e.,
occult dissection).
VIII. Postprocedure angiograms and access site hemostasis
1. Remove guidewire for final images after administering additional intracoronary (IC) nitroglycerin. Leaving the guidewire
in during final angiography may hold a dissection flap in place,
which would be missed if the guidewire had not been removed.
2. For the femoral approach, perform femoral angiography
before VCD selection (>30 degrees right anterior oblique
[RAO] for right femoral artery or left anterior oblique [LAO]
for left femoral artery). Avoid VCD in patients with scarring
from previous procedures.
3. Alternatively, if no closure device is used, secure sheaths in
place for later removal (2 hours) or when ACT is <160 seconds
for manual hemostasis for arterial sheaths. Do not use prolonged (>
complications are present. Increased bleeding risk is associated with postprocedure heparin infusions.
4. For radial procedures, apply radial artery compression band
with enough pressure to achieve patent hemostasis, maintaining good flow to hand. Remove band in 2 hours. Reapply if
hemostasis is not achieved.
IX. Postprocedure outside laboratory
1. Teach about hospital course and bleeding problems, late complications, and restenosis.
2. Notify referring physician and care team in recovery area or
critical care unit (CCU).
3. Use ECG and laboratory and telemetry monitoring of vital signs.
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Interventional Cardiology Procedures 429
6 hours) heparin infusions unless thrombus or other
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X. Post-PCI medications
XI. Follow-up schedule
Interventional Cardiology Procedures
1. The patient should take aspirin (325 mg orally daily for 1
month, then 81 mg/day indefinitely).
2. Prescribe clopidogrel (600-mg loading dose and 75 mg/day
orally) for at least 4 weeks after stenting with a bare metal stent
and 12 months with a drug-eluting stent. For patients with ACS,
prescribe prasugrel (60-mg loading dose and 10 mg/day orally)
or ticagrelor (180-mg loading dose and 90 mg/twice daily
orally). Second-generation P2Y12 receptor antiplatelet agents,
such as ticagrelor or prasugrel, are commonly used as alternatives to clopidogrel.
3. Initiate statin drugs if not already prescribed.
4. Restart antihypertensive or antianginal medications depending on patient’s clinical needs.
1. Check access site on first office visit.
2. Do not perform stress testing early after PCI or annually unless
symptoms or other clinical indications appear.
3. Repeat coronary angiography if symptoms or signs of ischemia
are present early after PCI.
4. Instruct patient to gradually return to activities of daily living.
Percutaneous Coronary
Intervention Pharmacology
See Chapter 1 for more information about commonly used drugs in
the catheterization lab.
Oral Antiplatelet Agents
All patients who undergo PCI receive aspirin, 325 mg/day for at least 1
month, with the dose reduced to 81 mg/day, indefinitely. In addition to
aspirin, another class of antiplatelet agents, clopidogrel (600-mg loading dose with 75 mg/day for 6 to 12 months as maintenance dose), is the
most commonly given, ideally before PCI. However, some patients do
not respond to clopidogrel because of a genetic predisposition. Clopidogrel is a prodrug and needs to be catalyzed to its active metabolite
by the cytochrome P450 2C19 (CYP2C19) enzyme. Some patients are
CYP2C19-poor metabolizers, leading to lower levels of the active metabolite of clopidogrel, less platelet inhibition, and increased risk of adverse cardiovascular events, including stent thrombosis, MI, and death.
As an alternate for patients with ACS, prasugrel (60-mg loading
dose with 10 mg/day maintenance), a P2Y12 receptor inhibitor, reduced
the combined rate of death from cardiovascular causes, nonfatal MI,
or nonfatal stroke but was associated with increased risk of bleeding
complications. Contraindications include a history of stroke or transient ischemic attack, age ≥75 years, and weight <
increased risk of bleeding.
ACS patients after PCI who were treated with another antiplatelet
agent, ticagrelor, showed improved clinical outcomes compared with
clopidogrel. In addition to reduction in the combined endpoints of
death from vascular causes, MI, or stroke, ticagrelor was associated
with a reduction in mortality compared with clopidogrel. Rates of fatal
or life-threatening bleeding were similar with clopidogrel. The loading
dose is 180 mg (two 90-mg tablets) and then 90 mg every 12 hours.
60 kg due to
Antithrombotic Agents
Heparin is a commonly used antithrombotic agent for PCI but is associated with a variety of limitations including variable anticoagulation
responses, heparin resistance, need to monitor degree of anticoagulation, risk of heparin-induced thrombocytopenia, and activation of
platelets.
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Bivalirudin is currently the most widely used anticoagulant for
PCI in the United States. It is a direct thrombin inhibitor and, when
compared with heparin plus GP IIb/IIIa inhibitor, is associated with
fewer bleeding complications across the full spectrum of patients with
coronary artery disease who undergo PCI. The HORIZONS-AMI trial
reported a reduction in 30-day mortality in ST-segment elevation myocardial infarction (STEMI) patients who underwent primary PCI with
bivalirudin as compared with heparin plus GP IIb/IIIa inhibitors.
However, planned GP IIb/IIIa inhibition is not routinely used in elective
PCI, and the use of this agent might explain the increased bleeding
found in the heparin groups studied.
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Interventional Cardiology Procedures 431
Stenosis Assessment in the
Catheterization Laboratory by
Pressure Sensor Guidewire:
Fractional Flow Reserve
The ischemic potential of a questionable or intermediate (40% to 70%)
lesion can be determined by FFR, which is the ratio of aortic pressure
(from the guide catheter) to poststenotic pressure measured from the
pressure guidewire beyond the stenosis during hyperemia (adenosine
IV infusion or IC bolus).
There are five steps to measure FFR:
1. Set guide catheter pressure and guidewire pressure to atmosphere
on the table (zero).
2. Advance the pressure guidewire to the central aortic position either
at the tip of the guide just inside the coronary artery or in the aorta.
3. Match the pressures of the guidewire and guide catheter before the
stenosis is crossed. This step is called pressure normalization or
equalization and eliminates any small differences in pressures
between the two systems.
4. Cross the lesions with the pressure wire 1 to 3 cm distally. Begin
recording pressures.
5. Induce hyperemia, most often with IV adenosine. Measure both
aortic and distal coronary pressures during adenosine-induced
hyperemia (preferred: 140 µg/kg/min × 3 to 4 minutes or, alternatively, IC 30 to 50 µg for right coronary artery [RCA] and 50 to
100 µg for left coronary artery [LCA]).
6. Compute FFR, the distal coronary pressure (Pd)/proximal aortic
pressure (Pa) ratio at maximal hyperemia.
FFR reflects the percent of normal blood flow through the stenosis. A normal value is 100% or 1.0. The FFR is an accurate reflection of
the ischemic potential of a stenosis. Before PCI in the patient example
in Figure 10-7, B,
guiding catheter. The Pd, measured from the sensor angioplasty guidewire, is 110/50 mm Hg. During IC administration of adenosine, the
hyperemic mean pressures (74 mm Hg/102 mm Hg) are used, yielding
an FFR of 0.72 (FFR <0.75 is associated with inducible ischemia). The
resting gradient (Pd/Pa) was insignificant and did not correlate with
inducible ischemia.
After PCI, the gradient between proximal and distal artery pressures is decreased or abolished. An FFR of >0.90 is considered a very
successful result. Normal arteries have FFR >0.94. In this patient after
PCI, the FFR is 0.98 (see Fig. 10-7, C).
A low FFR (<0.80), especially if the angiographic result is subop-
timal, is an indication for further treatment, often with stenting. FFR
is critically important when the operator is in doubt about the clinical significance of any lesion. The use of adjunctive imaging and
the Pa of 145/68 mm Hg is obtained through the
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