Note: Descriptions are shown in the official language in which they were submitted.
~32~31 5
~0355-54
PERFUSION OF PERFLUOROCARBON COMPOUND EMULSION
DURING PERCUTANEOUS TRAN5LUMINAL ANGIOPLASTY
This invention relates to percutaneous transluminal
angioplasty and more particularly to the perfusion of an
oxygenated perfluorocarbon compound emulsion during
prolonged angioplasty.
Restricted blood flow to body tissues may be caused
by a narrowing of arteries. This narrowing (or stenosis)
may be caused by a number of factors, such a athero
sclerosis, thrombus formation or trauma. For example,
; atherosclerosis refers to the gradual deposition of fatty
material, generally referred as atherosclerotic plaque,
on the inside walls of arteries. A build-up of
atherosclerotic plaque within an artery restricts the
flow of blood through the artery. The body or~an depend-
ing on the narrowed ~stenotic) artery eventually reacts
to the inadequate blood flow. The types of symptoms that
are produced from inadequate blood flow vary, depending
on which arteries in the body are narrowed. Percutaneous
transluminal angioplasty is a procedure for reopening
arteries narrowed by deposits of atherosclerotic plaque~
Angioplasty may be used in numerous sites, such aR
femoral, renal, cerebral and coronary arteries. In the
procedure, a small guiding catheter is inserted into a
vein and passed to the site of the narrowing or stenosis.
A smaller balloon-tipped catheter is passed through the
guiding catheter and positioned so that the balloon is
within the stenotic region of the artery.
Once in position, the balloon is inflated to enlarge
the inner diameter of the artery. In successful angio-
plasty, when the balloon is deflated, the stenosis of the
artery is less severe, thus providing a patient artery~
whiah permits more blood to pass through the artery to
the organ or tissue which was distal to the stenosis.
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1 322315
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When the balloon is inflated, the blood flow to the
tissue supplied by the arte.ry distal to the balloon is
cut off. Accordingly, the tima that the balloon can be
inflated is limited, particularly when the procedure
involves organs, which are extremely sensitive to the
lack of oxygen, such as the brain or heart. During a
single procedure the balloon may be inflated several
times. However, even with multiple inflations, tissue
elasticity and stenosis characteristics are such that a
significant proportion of the treated patients experience
restenosis of the treated artery within a few months.
Prolonged ir.flation of the balloon may result in
better resolution of the stenotic region. However~
prolonged balloon inflation results in prolonged periods
during which no oxygen is delivered to tissue distal to
the balloon. This creates risk to the patient. For
example, in percutaneous translum.inal coronary
angioplasty, prolonged bal.loon inflation results in
myocardial ischemia, arrhythmias and eventually
myocardial infarction.
Attempts to oxygenate tissue distal to the balloon
to enable a longer period of balloon inflation have
included perfusion of blood through the central lumen of
the catheter. However, the passage of blood through the
small diameter Qf the catheter lumen resulted in severe
hemolysis.
It has been found that prolonged balloon inflation
during angioplasty can be accomplished by passing an
oxygenated perfluorocarbon compound emulsion into the
artery through the lumen of the catheter.
Accordingly, the present invention comprises a
method for enlarging a stenotic region of an artery by
introducing a balloon catheter into the artery so that
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the balloon is positioned in the stenotic region. The
balloon is then inflated one or more times to enlarge the
inner diameter o~ the artery inflation of the balloon, an
oxygenated perfluorocarbon compound emulsion is passed
through the lumen of the catheter to supply oxygen to the
portion of the artery distal to the inflated balloon.
The flow rate of the perfluorocarbon compound emulsion
through the catheter is sufficient to prevent significant
ischemia, preferably being maintained within the range of
from about 20 cc/min to about 150 cc~minO
The number of balloon inflations at each stenotic
site can vary and may range from one up to about ten or
more as desired. Likewise, the duration of each
inflation may vary, generally being within the range of
from about 10 seconds to about 30 minutes.
These and other features and advantages of the
present invention will be better understood by reference
to the following detailed when considered in conjunction
with the accompanying drawings wherein:
FIG. 1 is a schematic view of a patient showing the
heart and main arteries involved in a percutaneous
transluminal coronary angioplasty;
FIG. 2 is an enlarged schematic view o~ the heart
showing the positioning of the guiding and balloon-tipped
catheters within a coronary artery; and
FIG. 3 is an enlarged fragmentary cutaway view of
the coronary artery and the balloon-tipped catheter.
A preferred application of the present invention is
in percutaneous transluminal coronary angioplasty. With
reference to FIGS. 1 to 3, such a procedure generally
consists of introducing an introducer sheath 10 into the
femoral artery 11 at the groin. A small guiding catheter
12 is inserted through the introducer sheath 10 and
passed through the femoral artery 11 and dorsal aorta 13
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~32231~
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and in~o the narrowed coronary art~ry 14 of the heart 16.
A smaller balloon-tipped catheter 17 is then passed
through the guiding catheter 12 and positioned so that
the balloon 18 o~ the balloon tipped catheter lies within
the stenotic region of the artery 14.
The balloon-tipped catheter 17 comprises a pair of
lumens 19 and 21. The first lumen 19 extends to the
balloon 18 and is used for passing a fluid, preferably
saline, to the balloon 18 to inflate the balloon, and to
pass fluid from the balloon 18 when the balloon is
de~lated.
The second lumen 21 extends through the balloon 18
to the distal tip 22 of the catheter 17. The second
lumen 21 is open at the distal tip. The second lumen 18
is provided for passing an oxygenated perfluorocarbon
emulsion through cathetex 17 into the occluded portion of
the artery 14 during balloon inflation.
As used herein, "perfluorocarbon compound emulsion"
refers to an aqueous emulsion of an oxygen-transferable
perfluorocarbon compound, preferably having a particle
size of less than about 0.3 microns. Suitahle emulsions
have good oxygen transferability to ischemic, hypoxic and
anoxic tissues, a favorable vapor pressure range to allow
reasonahle expiration of the perfluorocarbon compol~nds
used in the emulsion and clinically acceptable toxicity,
the emulsion may be transparent, translucent or opaque.
The perfluorocarbon compound emulsion comprises at
least one perfluorocarbon compound, an emulsifier and
physiological salts and monoglycerides thereof~ Such
perfluorocarbon compound emulsions are described in U.S.
Patent Nos. 3,911,138 to Clark, Jr., 3,962,439 to
Yokoyama et al and 4,252,827 to Yokoyama et al, Yokoyama,
K. et al- "A Perfluorochemical Emulsion as an Oxygen
,.~ "
1322~
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Carrier", Artificial Organs 8:34-40, 1984, and Yokoyama,
D. et al: "Selection of 53 PFC Substances for Better
Stability of Emulsion and Improved Artificial Blood
Substances", Advances ln Blood Substitute Research, New
York: Liss, Inc., 1983 .
Preferred fluorocarbon compound emulsions comprise
at least one perfluorocarbon compound having 9-11 carbon
atoms selected from the group consisting of perfluoro-
; decalin, perfluoromethyldecalin, perfluoro alkylcyclo-
hexanes having 3 to 5 carbon atoms in the alkyl~
perfluoro alkyltetrahydro~urans having 5 to 7 carbon
atoms in the alkyl, perfluoro alkyltetrahydropyrans
having 4 to 6 carbon atoms in the alkyl, perfluoroalkanes
having 9 to 11 carbon atoms, at least one perfluoro tert-
amine having 9 to 11 carbon atoms selected from the groupconsisting o~ perfluoro tert-alkylamines having 9 to 11
carbon atoms, perfluoro N-alkylpiperidines having 4 to 6
carbon atoms in the alkyl and perfluoro N-
alkylmorpholines having 5 to 7 carbon atoms in the alkyl;
a high-molecularweight nonionic surfactant having a
molecular weight of about 2,000 to 20,000; a
phospholipid; and at least one fatty acid compound
selected from the group consisting of fatty acids having
8 to 22 carbon atoms; and physiologically acceptable
salts and monoglycerides thereof. The ratio of the
perfluorocarbon compound and the said perfluoro-tert-
amine is 95-50 to 5-50 by weight.
The "high-molecular weight nonionic ~urfactant" has
a molecular weight of 2,000 to 20,000 and includes poly-
oxyethylene-polyoxypropylene copolymers, polyoxyethylene
alkyl ethers, and polyoxyethylene alkyl aryl ethers. The
concentration of the surfactant in the emulsion i9 about
2.0 to about 5.0%, preferably 3.0 to 3.5% (W/V).
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The symbol "% (W/V)" means -the amount proportion of
a material by weight (gram) based on 100 ml of the
resulting emulsion.
Examples of the perfluorocarbons having 9 to 11
carbon atoms are a perfluorocycloalkane or perfluoro
alkylcycloalkane which includes, for example/ perEluoro
C3s-alkylcyclohexanes such as perfluoromethylpropyl-
cyclohaxane, perfluorobutylcyclohexane, perfluorotri-
methylcyclohexane, perfluoroethylpropylcyclohexane,
perfluorodecalin and perfluoromethyldecalin; a perf:Luoro
C4_6-alkyltetrahydropyran such as perfluorohexyltetra-
hydropyran; a perfluoro Cs7-alkyltetrahydrofuran such as
perfluoro pentyltetrahydrofuran, perfluoro hexyltetra-
hydrofuran and perfluoro heptyltetrahydrofuran; and a
perfluoroal~ane having 9-11 carbon atoms such as perfluo-
rononane and perfluorodecane.
Examples of the perfluoro tert-amine having 9 to 11
carbon atoms are a perfluoro tert-alkylamine having 9 to
11 carbon atoms which includes, for example, perfluoro-
trialkylamines such as perfluoro N,N-dibutylmonomethyl-
amine, perfluoro N,N-diethylpentylamine, perfluoro N,N-
diethylhexylamine, perfluoto N,N-dipropylbutylamine and
perfluorotripropylamine; a per~luoro N,N-dialkyl-
cyclohexylamine having 9-11 carbon atoms such as
perfluoro N,N-diethy]cyclohexylamine; a perfluoro N-C4-6-
alkylpiper~idine such as perfluoro N-pentylpiperidine,
perfluoro N-hexylpiperidine and perfluoro M-
butylpiperidine; and a perfluoro N-C5-7-alkylmorpholine
such as perfluoro N~pentylmorpholine, perfluoro N-
hexylmorpholine and perfluoro N-heptylmorpholine.
The ratio of the perfluorocarbon compound to the
perfluoro tert-amine to be used is 50-95 to 50-5 by
weight and the total amount of perfluorocarbon compound
3 ~ ~
-- 7 --
and perfluoro tert-amine contained in the emulsion is
about 10 to about 50~ (W/V).
~ he phospholipids used as emulsifier adjuvant in the
invention are ones commonly used in the art, and those
comprising yolk phospholipid or soybean phospholipid are
preferable. The amount present in the emulsion ranges
from about 0.1 to about 1~0~ (W/V), and preferably about
0.4 to about 0.6% (W/V).
The fatty acid compound used as ernulsifying ad~uvant
is a fatty acid having 8 to 22 carbon atoms, a
physiologically acceptable salt such as sodium or
potassium salt or a monoglyceride thereof, which
includes, for example, caprylic acid, capric acid, lauric
acid, myristic acid, palmitic acid, stearic acid, behenic
acid, palmitoleic acid, oleic acid, linoleic acid,
arachidonic acid and sodium or potassium salt and
monoglyceride thereof. These fatty acid compounds may be
used alone or as a mixture of two or more kinds thereof
in such a minor amount of 0.004 to 0.1% (W/V), and
preferably about 0.02 to 0.04% (WIV). Among these fatty
acid compounds, the preferable ones are those having 14
to 20 carbon atoms and their physiologically acceptable
salts, and the most pre~era~le are potassium palmitate
and potassium oleate, taking into consideration of their
good solubility and ease of the preparation of the
emulsion.
The balloon-tipped catheter can be of any design
which comprises an inflatable balloon at its distal end
and a lumen which extends through the balloon and is open
at the distal tip of the catheter. Such catheters are
commercially available. Presently preferred catheters
include the Gruntzig Catheter manufactured by United
States Catheter, Inc. and the Simpson-Robert Coronary
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:L32231~
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Balloon Dilation Catheter manufactured by Advanced
Cardiovascular Systems.
Once the balloon is positioned within the stenotic
region of the artery, the balloon is i:nflated for a
5 select length of time, preferably from about 10 seconds
to about 30 minutes for procedures involving percutaneous
: transluminal coronary angioplasty.
During inflation of the balloon 18, an oxygenated
fluorocarbon compound emulsion is passed through the
; 10 second lumen 21 of the catheter 17 and into the arte~y 14
distal to the occlusion. The introduction of the fluoxo-
carbon compound emulsion into the artery may be commenced
before, simultaneously with or after the inflation of the
balloon. The fluorocarbon compound emulsion may be
administered at temperatures, between ambient (25C~ or
body temperature, (37C). The partial pressure of oxygen
(P02) in the emulsion is typically maintained in the range
of from about 300 mm~g to about 650 mmHg with p02's in the
upper portion of the range being preferred.
The rate at which the fluorocarbon compound emulsion
is introduced into the artery will depend on the size of
the artery which is being treated. The flow rate should
be sufficient to prevent physiologically dama~ing
ischemia. It is preferred that the flow rates be at
least about 20 cc per minute. Lower flow rates are not
preferred as they supply an insufficient amount of oxygen
to the occluded tissue. It is also preferred that the
flow rate does not exceed about 150 cc per minuts.
Greater flows are not preferred because they tend to
generate high pressures within the artery which may cause
rupture.
In order to minimize flow interruption during the
procedure, it is preferred that the fluorochemical com-
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1 ~223~
g
pound emulsion be injected into the catheter from a large
sterile reservoir, e~g., up to 1000 ml volume, which can
be refilled during the procedure.
The present invention is particularly suited to
percutaneous transluminal coronary angioplasty procedures
during coronary operations, e.g., to inflate a collapsed
artery while supplying oxygen to the t:issue cut off by
the collapse. It is also applicable to open blockecl
coronary arteries and supply oxygen to ischemic tissue
during or following myocardial infarction.
A similar, and equally applicable application of the
present invention is in retroperfusing oxygenated
perfluorocarbon compound emulsion irto coronary veins cut
off from oxygen by occlusions in a coronary artery. In
such an application, the balloon catheter is introduced
into the coronar~ sinus. During diastole, the balloon is
inflated and the oxygenated perfluorocarbon emulsion is
retroperfused into the coronary veins. Inflation times
are generally less than a second.
The preceding de~cription has been presented with
reference to a presently preferred application of the
invention, i.e., percutaneous transluminal coronary
angioplasty. It is apparent that the invention is
equally applicable to other percutaneous transluminal
angioplasty procedures, e.g., renal, femoral or carotid
including inter-operative procedures involving such
arteries. It is also apparent that, depending on the
specific procedure, the parameters of the procedure may
vary. For example, for percutaneous transluminal
angioplasty of arteries other than those serving the
heart and brain, the preferred duration of each balloon
inflation is at least about two minutes. For the carotid
artery and other vessels serving the brain, it is
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~3223~5
- 10 -
believed that durations of from about ten seconds to
about fifteen minutes can be used.
It is also apparent that, if desired, oxygenated
perfluorocarbon compound emulsion can be administered
through the guiding catheter or other catheters to supply
oxygen to the tissue proximal to the inflated balloon.
Additional perfluorocarbon compound emulsions may be
admini~tered through perepherial I.V. lines, if desired.
The present invention offers the advantages that
prolonged balloon inflation times can now be practised
without resultant physiologically damaging ischemia~
Moreover, the present invention enables the angioplasty
procedure to he per~ormed on multiple sites within a
single vessel or in multiple vessels, again without
~ 15 resultant ischemia.
i EXAMPLE I
Twelve adult mongrel dogs, weighing 20 to 30 kg,
were anesthetized with pentobarbital, 25 mg/kg I.V., and,
after intubation, were placed on a Harvard volume
respirator. An electrocardiogram was monitored and
recorded continuously throughout the study. Bilaterial
carotid artery cutdowns were performed, and a #8 French
Millar end-tip manometer catheter was advanced to the
left ventricle under fluoroscopic control for continuous
monitoring of pressure and dp/dt. A #10 French guiding
catheter was advanced to the osti~m of the left coronary
artery under fluoroscopy; and a 3.0 mm balloon catheter
(either the USCI Gruntzig catheter or the ACS Simpson-
Robert catheter) was passed, coaxially through the
guiding catheter, into the circumflex branch. In one
dog, the balloon catheter was placed in the left anterior
descending branch (dog #7)~ Heparin, 5000 units, was
given i.v. in each dog. No anti-arrhythmic drugs were
given to any dog at any time.
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~322315
11 -
Fluosol-DA1 20% was oxygenated ~y bubbling oxygen
through a tube into the solution for 30 minutes~ In this
manner, a P02 Of 600 mmHg was achieved. When 100% oxygen
was passed over Fluosol-DA 20%, in a vlented bottle while
the solution was slowly swirling, similar oxygenation
(600 mmHg) was obtainable.
The infusion of Fluosol-DA 20% -through the central
lumen of the balloon catheter was initiated be~ore
balloon inflation and after recording the baseline ECG,
~V pressure; and dp/dt at 50 mm/sec paper speed. A low
flow roller pump was used to deliver the Fluosol-DA 20%.
The flow rate, which had been already measured before
insertion of the balloon catheter, was again determined.
If the flow rate was satisfactory, the balloon was then
inflated; if not, the flow was adjusted to the desired
level before balloon inflation. Inflation of the balloon
was performed with contrast medium, so that the inflation
could be followed fluoroscopically. Contrast medium was
injected into a proximal portion of the left main
coronary artery through the guiding catheter, after
balloon inflation, in order to confirm that the inflation
resulted in complete occlusion of the branch to the
antegrade flow of blood.
The ECG, LV pressure, and dp/dt were recorded
periodically at 50 mm/sec paper speed during the infusion
and, in the majority of the dogs, during the 15 to 30
minute period following the completion of the Fluosol-DA
20% perfusion. A postmortem examination of the heart was
performed at the end of each study by sectioning the
myocardium at 1 cm intervals and by making a longitudinal
1 Fluosol-DA 20% is a trade mark for a perfluorocarbon
compound emulsion manufactured by the Green Cro5s
Corporation of Osaka, Japan
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1 3223~
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incision along the length of all major branches of the
coronary arteries.
Dogs were perfused with Fluosol-DA 20% at flow rates
ranging from 5 to 30 ml/min while balloon inflation times
ranged from 8 to 53 minutes. No dog in the Fluosol-DA
20% group died prematurely, i.e., before comple~ion of
the Fluosol-DA 20% perfusion and post-perfusion periods
of observation had ended. The baseline data was obtained
after approximately 15 to 45 seconds of balloon occlusion
with no infusion of any oxygenated material through the
distal port of the catheter.
Perfusion with Fluosol-DA 20% was inadequate in Dog
#3 (only 5 cc/min), since Silastic tubing was used in the
roller pump. This tubing collapses excessively with
movement of the roller pump head, so that a higher flow
rate could not be achieved in this dog. ST segment
depres~ion on the ECG occurred, while no hemodynamic or
post-mortem changes were noted. With the use of tygon
tubing in the other 11 dogs any desired flow rate was
easily achieved.
;
In Dog ~7, the balloon catheter could not be placed
in the circumflex branch and was therefore placed in the
left anterior descending branch. The latter had numerous
large side branches (diagonal and septal perforators),
four or five of which were obstructed by the inflated
~alloon. These branches, which were proximal to the tip
of the balloon catheter, could not receive Fluosol-DA
20%, and it was not surprising, therefore, that
hemorrhage in the distribution of these branches (the
septum) was found. Marked ST-T wave changes on the ~CG
occurred wi-thin seconds of balloon inflation, while
systemic pressure fell to 75 mmHg. Of interest in this
study was the observation that the fre~uency of baseline
PVC's, 6.8% of the normal beats, decreased to 4.3% during
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1 3223~5
- 13 -
Fluosol infusion, and increased markedly in the post-
infusion period to 19.8%~
In Dog #12, the balloon catheter was advanced quite
far distally, due to the large size of the circumflex
artery in the dog, and balloon inflation resulted in
obstruction of a moderate sized branch. Elevation of the
ST segment on the ECG occurred within several minutes
and, on postmortem examination~ a smal:L area of
hemorrhage over the epicardium only (no intramural
changes were seen) was noted in the region corresponding
to the obstructed branch. There were no hemodynamic
effects of this occlusion, and no arrhythmias occurred.
In the remaining nine dogs, there were no EKG
changes, no arrhythmias, no adverse hemodynamic ~effects,
and no abnormal postmortem pathology demonstrable either
during or after myocardial perfusion with Fluosol-DA 20%.
EXAMPLE II
An additional control animal was investigated in
which oxygenated saline (P02 greater than 600 mmHg) was
passed through the distal paxt of the catheter. In this
animal the procedure was carried out exactly as in dogs 8
through 12 of Example I, but oxygenated saline was
infused at 60 ml/min into the coronary artery. This dog
developed ventricular fibrillation and died within two
minutes.
EXAMPLE III
A second animal wa~ also prepared similar to dogs 8
though 12 of Example I. This animal received a pre-dose
of methylprednisolone (10 mg/kg) at 24 hours and 10
minutes pre-infusion~ This animal received (30 ml/min)
Fluosol-DA 20% for eight minutes. No abnormalities were
observed, but after a 15 minute recovery period the
procedure was aborted.
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~322315
~ 14 -
EXAMPLE IV
Thirty-one human patients were randomized into
Fluosol-DA 20% (F-DA) treated (n=14) and control ln=17)
groups prior to elective percutaneous transluminal
coronary angioplasty (PTCA), which was initially
performed in all patients in a routine manner. In the F-
DA group, following steroid premedication and a 3.5~c
i.v. test dose, i.c. F DA was infused at 0.5cc/sec x 1
min. before and during balloon inflation if routine PTCA
had been performed without difficulty (n=lO). In
response to PTCA, the two groups did not differ
clinically, angio-graphically, hemodyn~mically, or by
serial ECG's. RA, PA, and PA wedge pressures each
increased slightly in both groups immediately following
PTCA (P .05), but these changes were not different
between groups. Coagulation profiles, blood chemistries,
and CBC's before and one day after PTCA did not differ
between groups, except for a greater W~C rise in the F-DA
group (P .01~, which very likely resulted from the
steroid medication.
EXAMPLE V
In a cross-over study involving twenty-five human
patients, each patient was treated with a routine (single
inflation) PTCA procedure and then randomized to receive
additional PTCA procedures using perfusion with
oxygenated Fluosol-DA 20% ~F-DA) and then oxygenated
lactated Ringer's solution or the reverse.
Electrocardiograms (EKG) (abnormalities in EKG vallles are
indicators of physiological ischemia) were obtained for
each patient during each procedure and the duration of
any EKG abnormalities were assessed for each portion of
the study. In 18 of the 25 patients the duration of EKG
abnormalities was significantly longer (P 0.05) during
lactated Ringer's PTCA than during F-DA PTCA as shown in
Graph I below.
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~322315
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These EKG abnormalities lasted 15.5 ~ 9.7 seconds
longer during lactated Ringer's-PTCA than durin~ F DA
PTCA. This difference is suppressed due to early
termination of lactated Ringer's-PTCA procedure in 8
patients after marked EKG changes and/or anginal pain wa~
experienced by the patient.
EXAMPLE VI
The severity of anginal pain (a measure of physio
logical ischemia) experienced during each phase of the
PTCA procedure described above in Example V was also
assessed. The results are shown in Graph II below.
The severity of anginal pain was scored on a ten
point scale with zero equal to no pain and nine
representing unbearable pain. Of the 25 patients, 11
patients had pain of the same score with either prolonged
dilatation procedure. Twelve patients had less severe
pain with F-DA-PTCA than with lactated Ringer's-PTCA.
The mean difference in severity pain scores was 1.7.
Pain experienced during F-DA-PTCA was significantly
(p=0.002) less than during lactated Ringer's-PTCA.
Although the duration of the pain was similar, the
time to onset and the severity of pain were signiicantly
improved with F-DA-PTCA as a prolonged dilatation
procedure compared to lactated Ringer's-PTCA.
EXAMPLE VII
The stenotic gradients of the treated vessels were
also assessedO The results are shown in Graph III below.
The stenotic gradient is the pressure on the proximal
side of the stenotic lesion subtracted from the pressure
on the distal side of the lesion. A reduction in the
stenotic gradient after PTCA is a measure of the improve-
ment of vessel architecture afected by the procedure.
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A stenotic gradient of less than 20 mm Hg after PTCA
indicated a successful procedure while a procedure giving
a gradient of less than 16 mm Hg is considered to give
results equivalent to a coronary artery bypass graft
procedure (CABG).
In 8 of 25 patients, the trans-stenotic gradient was
further reduced as a result of prolonged dilatation of
the diseased vessel~ Improved vessels included six L~,
one RCA and one CIRC. In 7 of these 8 patients, the
gradient was reduced to 20 mm Hg or less with the
prolonged dilatation--an indication of successful PTCA
results.
To achieve coronary flow reserve post-PTCA, which
would be equivalent to CABG, the achieved gradient should
be 16 mmHg. Following Routine-PTCA the success of
achieving a trans-stenotic gradient 16 mm Hg was only
60%; the success rate was increased to 76~ with the
prolonged dilatation procedures. The prolonged
dilatation also improved the gradient in three patient~
to 17, 19 and 20 mm Hg from post Routine-PTCA levels of
35, 28, and 43 mm Hg, respectively.
Following Routine-PTCA, 76% of the patients had
reduced gradients lower than the critical gradient
associated wikh a loss of hyperemic reserve (32 mmHg).
After prolonged dilatation, the success rate was
increased to 96% of the patients.
Overall, prolonged dilatation improved the trans-
stenotic gradient in 32% of the patients (mean
improvement of 18.6 mmHg) compared to results following
routine-PTCA suggesting that the artery lumen contour was
improved in those patients.
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