Catheterization and Cardiovascular Diagnosis 36:ll-16
(1995)
Influence of Expanded Balloon Diameter on
Palmaz-Schatz Stent Recoil
Eldad Rechavia, MD, Frank Litvack, MD, Gail Macko, RN, and Neal L. Eigler, MD
After successful stent implantation, the residual luminal diameter of the stented vessel is
usually smaller than the maximal stentexpanded balloon diameter. The goal of this study
was to determine whether Immediatevessel diameter recoil after Palmaz-Schatz stenting
is affected by the final expanding balloon diameter used during stent deployment.
Single Palmaz-Schatz balloon expandable stents were successfully placed in 108
stenotlc lesions. There were 68 patients with 75 saphenous vein graft (SVG) and 30
patients with 33 native coronary artery lesions, including 26 restenotic and 82 de novo
occlusive (>50% diameter stenosis) lesions. Quantitative coronary angiography was
used for the assessment of stent recoil, defined as the difference between the minimal
diameter of the fully expanded balloon and the postprocedure minimal lumen diameter
divided by mlnimal diameter of the fully expanded balloon.
A strong correlation (r = 0.94) was found between the minimal diameter of the fully
expanded balloon and poststenting minimal lumen diameter. Immediaterecoil was 11.3 f
7.570, responsible on an average for 0.4 f 0.2-mm acute lumen loss. Recoil was less in
SVG than in coronary arteries (9.7 2 6.6% vs. 14.0 2 7.8%; P = 0.004, and 0.3 f 0.2 vs.
0.4 f 0.2 mm; p = 0.01). Lesions were divided into four subgroups, based on the final
stent expanding balloon diameter: (1) 53.0 mm (n = 33); (2) >3 5 3.5 mm (n = 43); (3)
>3.5 5 4 mm (n = 23); and (4) >4 mm (n = 9). For the four subgroups, the percentage
recoil values were 15.0 f 5.7,10.4 f 8.2,g.O
5.4, and 4.7 f 2.0, respectively (P < 0.001).
Mean values of diameter stenosis, lesion length, maximal balloon pressure, balloon-toartery ratio, relative vessel stretch, and absolute recoil were not statistically different.
Immediatevascular recoil in single implanted Palmaz-Schatz stent is a function of the
final expanding balloon diameter, with recoil larger at small-balloondiametersand almost
eliminated at large inflation diameters. This finding could contribute to less acute gain,
increased restenosis, and higher stent thrombosis rates after stenting vessels of <3-mm
diameter. o 1x15 W l l e y - L i ~ ,inc.
*
Key words: balloon angloplasty, coronary artery disease, saphenous vein graft
INTRODUCTION
MATERIALS AND METHODS
Palmaz-Schatz stent implantation is now an important
therapeutic option for diseased native coronary arteries
and saphenous vein grafts (SVG) [ 1-41. The best clinical
outcomes have been reported in vessels with large reference diameter in which optimal acute gain has been
achieved [ 5 ] . Only one size of Palmaz-Schatz device is
available for the treatment of vessels, ranging from 3 to
6 mm, albeit delivered on different balloon diameters.
Studies of the mechanisms of acute lumen loss after
balloon angioplasty or stent implantation have traditionally focused on procedure-related variables and lesion
morphology. Little is known about the in vivo elastic
behavior of the mesh architecture of the articulated Palmaz-Schatz coronary stent at different expansion diameters. Our goal was to examine quantitative angiographic
variables in relationship to the minimal diameter of the
largest fully expanded balloon used for stent deployment.
Patient Population
0 1995 Wiley-Liss, Inc.
Angiograms satisfactory for quantification were available for 108 lesions in 98 patients successfully treated
with a single Palmaz-Schatz coronary stent between January 1992 and April 1994 at Cedars-Sinai Medical Center. This represents 6.2% of the 1,7 19 patients who underwent percutaneous transluminal coronary angioplasty
From the Cardiovascular Intervention Research Center, Division of
Cardiology, Department of Medicine and Medical Research Institute
of Cedars-Sinai Medical Center and the UCLA School of Medicine,
Los Angeles, California.
Received November 18, 1994; revision accepted February 2, 1995
Address reprint requests to Neal L. Eigier, M.D., Cardiovascular
Intervention Center, Cedars-Sinai Medical Center, 8700 Beverly
Bivd., Rm 6558, Los Angeies, CA 90048.
12
Rechavia et al.
(PTCA) during the same period. The indications for
choosing stent as the primary treatment device was at the
discretion of the individual operator. All patients had
>50% narrowing either in SVG or in the native coronary
vessel. A successful procedure was defined as <30%
residual stenosis of the poststenting angiogram. Seventyfive SVG lesions were stented in 68 patients, and 33
coronary arteries lesions in 30 patients. There were 26
restenotic and 82 de novo lesions. Thirty-three stents
were placed at aorto-ostial locations (lesions 1 3 m m for
the vessel origin).
All patients had objective evidence of myocardial
ischemia, and their target vessel was large enough to
accept a 2 3 m m stent. Fifteen (15%) patients had stent
implantation following suboptimal balloon or laser angioplasty. The mean age of the patients was 69 2 12
years, 90% were male, and 53% and 47% had stable or
unstable angina, respectively.
Stent Implantation
cording to whether stents were placed in vein grafts or
native coronary arteries. Subsequently, all stent cases
were categorized into four subgroups based on the minimal diameter of the largest fully expanded balloon during stent deployment: ( 1 ) 1 3 mm (n = 33), (2) >3 I
3.5 m m ( n = 43), (3) >3.5 5 4 m m ( n = 23), and(4)
>4 m m ( n = 9).
Statistics
Data are presented as mean value 2 S D . Comparisons
of continuous variables between vein grafts and native
coronary arteries were by Student’s r-test. Multiple subgroups comparisons were by one-way analysis of variance (ANOVA). If significant differences were found ( P
< 0.05),post hoc pairwise intergroup comparisons were
performed by the adjusted t-test within ANOVA (least
significant difference test). Analysis of scattergram plots
was performed using linear regression analysis. Statistical significance was defined as P < 0.05.
All patients received the 15-mm articulated PalmazRESULTS
Schatz stent. The implantation procedure was performed
Table 1 summarizes the demographic and quantitative
as previously described [ 11. After initial deployment, all
stents were further expanded with larger-diameter or angiographic variables in stented vein grafts and native
high-pressure balloons to leave a minimal residual ste- coronary arteries. The vein graft patients were signifinosis. The mean maximal balloon pressure used was 10 cantly older (71 10 vs. 63 13 years; P = 0.001) and
k 4 atm. Antiplatelet and warfarin therapy were given as had a larger reference diameter (3.2 2 0.6 vs. 2.9 5 0.5
previously recommended [ 11. Intracoronary nitroglyc- mm; P = 0.01), a larger pre-MLD (0.7 ? 0.4 vs. 0.5 ?
erin (0.1-0.3 mg) was administered both before and af- 0.3 mm; P = 0.003), and less severe diameter stenosis
ter stent deployment.
12 vs. 82
10%; P = 0.03). There was no
(77
difference in lesion length.
Data Analysis
As expected, a larger minimal diameter final balloon
Cineangiograms were analyzed by a single experi- size (BAL) was measured in the SVG compared to native
enced observer (ER), using an automated computer-as- coronary patients (3.4 0.5 vs. 3.1 2 0.4 mm, respecsisted edge-detection system (Imagecomm Systems), tively; P = 0.002), but there was no difference in the
with magnification calibrated from the guiding catheter balloon-to-artery ratio (1.1 L 0.2 vs. 1.1
0.1, re[6]. We have previously measured the mean absolute spectively), maximal balloon pressure (10 4 vs. 9 ? 3
error for vessels 1-3 mm in diameter to be 50.04 mm. atm, respectively), absolute (2.7 k 0.6 vs. 2.6
0.5
End-diastolic frames showing the most severe narrowing mm, respectively), or relative (0.86 2 0.27 vs. 0.91 ?
in the projection that best demonstrated the target lesion 0.18; respectively) vessel stretch. The minimum lumen
with the least forshortening were selected. The following diameter after stenting was significantly greater in vein
measurements were obtained: reference vessel diameter graft patients (3.1 t 0.6 vs. 2.7 0.5 mm, P < 0.001),
(RD); pre- and postprocedure minimal lumen diameter corresponding to an acute gain of 2.4 2 0.7 vs. 2.2
(pre-MLD and stent-MLD, respectively); lesion length; 0.5 mm, respectively (P-NS) and percentage residual
minimal diameter of the largest fully expanded balloon stenosis of 2 2 19% vs. 6 2 11% (P-NS). Absolute and
after stent deployment (BAL). Calculated indices in- relative diameter recoil were significantly less in vein
cluded percentage stenosis pre [(RD-pre-MLD)/RD* graft lesions than in native coronary lesions (0.3 2 0.2
1001 and postprocedure [(RD-stent-MLD)/RD*1001; mm vs. 0.4 2 0.2 mm; P = 0.01, 9.7 ? 6.6% vs. 14.0
balloon-to-artery ratio (BALIRD); acute gain (stent- 2 7.8%; P = 0.004).
MLD-pre-MLD); absolute recoil (BAL-stent-MLD); perRegression analysis was performed to determine
centage recoil [(BAL-stentMLD)/BAL*1001, absolute whether differences in stent-MLD and recoil were related
vessel strech (BAL-pre-MLD), and relative vessel to such factors as the type of vessel stented, or to the final
stretch [(BAL-pre-MLD)/RD* 1001.
balloon diameter used for stent expansion. Figure I
Clinical and angiographic variables were analyzed ac- shows that there was a strong correlation between stent-
*
*
*
*
+_
*
+_
+_
*
*
Stent Recoil
13
TABLE 1. Demographic and Quantitative Parameters: Vein Grafts Versus Native
Coronary Arteries
Vein graft (N
No. of patients
Malelfemale
Patients' age (years)
RD (mm)
Pre-MLD (mm)
Diameter stenosis (96)
Lesion length (mm)
Balloon diameter (mm)
Balloon-to-artery ratio
Balloon pressure (atm)
Stretch (mm)
StretchlRD (%)
Stent-MLD (mm)
Residual stenosis (a)
Acute gain (mm)
Recoil (mm)
Recoil (%)
=
75)
68
6018
71 ? 10
3.2
0.7
2
0.6
2 0.4
77 2 12
5.9 2 2.9
3.4 t 0 . 5
1 . 1 ? 0.2
10 2 4
2.7 ? 0.6
86 2 27
3.1 t- 0.6
2 ? 19
2.4 t- 0.7
0.3 t- 0.2
9.7 ? 6.6
Coronary (N = 33)
r-test P value
30
22/8
63 t 13
2.8 ? 0.4
0.5 t 0.3
83 ? 10
4.9 2 3.2
3.1 t 0.4
1 . 1 t 0.1
9 t 3
2.6 t 0.5
91 5 18
2.7 t 0.5
6 t 11
2.2 5 0.5
0.4 5 0.2
14.0 t 7.8
-
0.001
0.003
0.003
0.03
0.17
0.002
0.74
0.15
0.5 I
0.36
<O.Ool
0.20
0.12
0.01
0.004
Abbreviations: MLD, minimal lumen diameter; RD, reference diameter.
MLD and the diameter of the minimal diameter of the
largest inflated balloon (r = 0.93 for SVG and r = 0.85
for native arteries). When SVG and native coronary data
were pooled together, the regression coefficient increased to 0.94. The vertical distance between each data
point and the line of identity in Figure 1 represents the
absolute recoil. These data suggest that the differences in
final stent-MLD and recoil between native coronary and
vein graft vessels are related most closely to the achieved
balloon diameter. The final lumen diameter was less associated with the reference diameter of the stented vessel
(r = 0.57).
Linear correlations were also documented between
maximal balloon dilation and acute gain (r = 0.73),
maximal balloon dilatation and relative recoil (r = 0.47;
Fig. 2) and relative or absolute recoil and acute gain (r
values 0.62 and 0.51, respectively). Neither absolute nor
relative recoil correlated with balloon-to-artery ratio, reference vessel diameter, balloon inflation pressure, absolute or relative stretch (r values <0.30).
Absolute and relative recoil as well as acute gain were
not significantly different for de novo and restenotic lesions (0.3 2 0.2 vs. 0.4 ? 0.2 mm; 10.7 2 6.2% vs.
12.7 f 8.1%; 2.3 f 0.5 vs. 2.3 +- 0.6; respectively;
P-NS). Interestingly, s t e m deployed at aorto-ostial locations had less absolute and relative recoil than at non
ostial locations (Table 11). This was associated with a
larger final balloon diameter in aorto-ostial locations.
Table 111 shows the subgroup data based on the minimal final balloon diameter. The four subgroups were
similar with regard to age, percentage diameter stenosis,
and lesion length. There was a trend (P = 0.05) toward
larger pre-MLD in vessels with the largest (>4-mm) bal-
Mmsvg = -o.ror+i.116'maxBAL; ~ 0 . 9 3
MLDcor = -0.52+1.025?1axBAL; ~ 0 . 8 5
5,
4 SVG
2
3
4
5
*=.
CORONARY
Maximum Balloon Diameter (mm)
Fig. 1. Scatterplots showing the correlation between poststenting minimal lumen diameter (stent-MLD) and minimal diameter of the largest fully expanded balloon (BAL) used during
stent deploymentfor SVG and coronary arteries lesions as measured by quantltative coronary anglography.
loon diameter. The mean inflation pressures and balloonto-artery ratios were not statistically different, although
balloon-to-artery ratio was slighty lower in the group
with the smallest balloon diameter (1.03 ? 0.13 vs. 1.09
f 0.18 in the entire study group). There was a trend for
absolute recoil to decrease at larger diameter from 0.4 2
0.2 mm for balloon diameter 1 3 . 0 mm compared to 0.2
? 0.1 mm for diameter >4.0 mm ( P = 0.05). When
recoil was normalized with respect to the inflated balloon
diameter to yield percentage diameter recoil, there was a
highly significant fall in recoil with progressive increases
14
Rechavia et al.
15 k 11% stent recoil in vessels with reference diameter
averaging 3.0 mm.
RD
BAL
Recoil
Recoil
The most important observation of this study is the
(mm)
(mm)
(mm)
(%)
degree of balloon expansion best determines stent recoil.
0.3 t 0.2
7.4 2 5.3
3.6 2 0.4
Ostial
3.3 2 0.6
Recoil is not affected by lesion type (de novo vs. rest12.6 * 7.4
0.4 t 0.2
3.2 +- 0.4
Nonostial
3.1 ? 0.6
enotic), location (ostial versus nonostial), graft age, or
0.006
0.001
P-value
0.4
<0.001
demographic factors. The higher absolute and relative
Abbreviations: BAL. balloon; RD. reference diameter.
recoil in native coronary arteries compared to vein grafts
is likely related to the disparity in reference diameter,
resulting in the choice of a smaller balloon and therefore
in BAL. When the inflated balloon was 5 3 . 0 mm, recoil a smaller final expanded balloon diameter. Our findings
averaged 15.0 2 5.7%, whereas when the inflated bal- differ from those of Haude et al. [HI, who reported that
loon was >4.0 mm, recoil declined by more than three- nominal balloon size did not affect recoil. This may be
fold to 4.7 t 2.0% (P < 0.001). As expected, absolute explained by several methodological differences: these
vessel stretch increased with larger balloon diameter but, investigators studied fewer patients, did not include vein
when adjusted for the vessel reference diameter, there graft patients, used different quantitative angiographic
was a trend but not a significant effect of balloon size. methods and definitions, and did not make comparisons
with the actual final balloon diameter.
TABLE 11. Recoil Characteristics of Aorto-ostial Versus
Nonostial Stented Lesions
~
~
DISCUSSION
Mechanism of Vascular Recoil After Stenting
This study demonstrates that final minimal lumen diameter and acute vessel recoil after Palmaz-Schatz stenting in SVG and native coronary arteries is most closely
related to the final expanding balloon diameter. Other
variables, including lesion type (de novo vs. restenotic),
stenosis severity or location (ostial vs. nonostial), lesion
length, balloon pressure, vessel stretch, and balloon-toartery ratio did not affect acute recoil after stent deployment.
Our analysis of recoil was based on the minimal value
of the balloon diameter as recommended by Hermans et
al. [19] and minimal lumen diameter after stenting.
These workers have concluded that this measurement
best reflects the narrowing persisting at the site of the
severest residual narrowing. However, it is conceivable
that different conclusions could be reached using other
recoil definitions [8].
The Palmaz-Schatz stent is not readily visualized by
cineangiography. It is therefore not possible to determine
the frequency with which the minimal stented region
diameter is due to tissue protruding through the articulation site of the stent versus incomplete stent strut expansion. Our experience with intravascular ultrasound
shows that the minimally expanded segment occurs at the
articulation or elsewhere at the site of previous stenosis
with approximately equal frequency. Thus, it cannot be
fully ascertained whether the higher absolute and relative
recoil seen with lesser degrees of balloon expansion represents an inherent property of the elastic behavior of the
stent strut architecture or the articulated bridge design
geometry.
Regardless of the precise mechanism, it is conceivable
that the greater acute recoil seen with smaller degrees of
balloon expansion may play an important role in determining the higher rates of subacute thrombosis and late
restenosis associated with stenting smaller vessels [ 11.
These effects cannot be assessed by follow-up evaluation
of the small number of patients in our study. This would
require a much larger data base of several thousand patients to achieve significance at sufficient statistical
power. Meanwhile, ongoing studies with intravascular
ultrasound-guided optimal stent expansion may limit this
phenomena [20], or alternatively, newer stent designs
Balloon Versus Stent Recoil
Early vascular recoil is an important mechanism of
early restenosis following conventional balloon angioplasty. Nearly 30% of the vessel diameter gained by
balloon stretching is lost immediately after balloon angioplasty [2,7-121. Compared with balloon angioplasty,
the Palmaz-Schatz stent is more effective in diminishing
recoil [2,8,9,13] and has been shown to reduce angiographic restenosis in vessels with reference diameters
>3.0 mm in two randomized trials comprising a total of
930 patients [2,3]. In stented vessels, restenosis is related predominantly to late lumen encroachment by intima1 hyperplasia within the stent while late stent compression has been shown not to be an important
component for late lumen loss [ 141.
Stent Recoil
The magnitude of immediate stent recoil has been reported to average 3.5-17% in native coronary arteries
[2,8,15-18], but few data are available for vein grafts.
Our stent recoil data in native coronary arteries are very
similar to that reported by the STRESS trial [2]. Using
the same definition of recoil, these investigators reported
Stent Recoil
15
TABLE 111. Subgroup Analysis of 108 Lesions Based on Minimal Diameter of Largest Fully Expanded Balloon Used During
Stent Dedovment
Balloon-D Imm)
No. of cases
Patients' age (years)
Pre-MLD (mm)
RD (mm)
D-stenosis (%)
LL (mm)
BP (atm)
Balloon-to-artery ratio
Stretch (mm)
StretchlRD (%)
Stent-MLD (mm)
R-stenosis (%)
Acute gain (mm)
Recoil (mm)
Recoil (76)
Group I
13
Group 2
>313.5
Group 3
>3.554
Group 4
>4
33
67 t 12
0.6 f 0.3
2.9 f 0.4
75 t 13
5.1 t 3.0
10 t 4
1.0 5 0.1
2.1 t 0.4
80 t 20
2.4 C- 0.2
12 f 10
1.7 f 0.4
0.4 t 0.2
15.0 2 5.7
43
70 f 13
0.6 k 0.4
3.1 f 0.5
79 f 9
5.3 5 2.8
9 5 4
1.1 5 0.2
2.7 f 0.4
90 f 23
3.0 2 0.4
I t 15
2.4 f 0.4
0.3 t 0.3
10.7 t 8.2
23
70 k 9
0.8 k 0.4
3.3 f 0.5
76 k 14
5.3 ? 2.7
11 f 4
1.2 f 0.2
3.0 f 0.4
92 k 22
3.4 k 0.3
O f 12
2.7 ? 0.5
0.3 2 0.2
9.0 f 5.4
9
6 6 k 13
1.0 k 0.6
3.9 2 1.0
77 k 10
5.9 k 3.8
9 5 3
1.2 f 0.2
3.4 2 0.6
95 k 40
4.1 k 0.3
-4 t 14
3.2 f 0.6
0.2 f 0.1
4.7 k 2.0
ANOVA
P value
0.59
0.05
<0.001
0.63
r-test within
ANOVA
2;3
-
0.91
0.53
0.08
<O.oOI
0. I4
<0.001
0.005
<O.oOI
0.05
<O.oOI
2;3
Abbreviations: B, balloon; BP, balloon pressure; D, diameter; LL, lesion length; MLD, minimal lumen diameter; R. residual; RD, reference diameter.
r-test within ANOVA: 2;3 denotes a nonsignificant difference between groups 2 and 3 when ANOVA P value is <0.05.
"T-test within ANOVA confirms a significant difference among four groups.
rn
rn
REFERENCES
rn
I
*
*
10
0
2
3
4
5
Maximum Balloon Diameter (mm)
Fig. 2. Scatter plot showing the correlation between balloon
diameter and relative recoil in 108 stented lesions.
that reduce recoil at smaller expansion diameters may
minimize acute recoil, thereby maintaining maximal final lumen diameter.
ACKNOWLEDGMENTS
Dr. E. Rechavia is supported in part by the Save A
Heart Foundation Lillian Goldstein Fellowship, Los Angeles, California. He is a recipient of fellowship from
I . Schatz RA, Baim DS, Leon M, Ellis SG, Goldberg S, Hirshfeld
JW, Cleman MW, Cabin HS, Walker C, Stagg J, Buchbinder M,
Teirstein PS. Topol EJ, Savage M, Perez JA, Curry RC, Whitworth H, Sousa JE, Tio F, Almagor Y , Ponder R, Penn IM,
Leonard B, Levine SL, Fish DR, Palmaz JC: Clinical experience
with the Palmaz-Schatz coronary stent: initial results of a multicenter study. Circulation 83:148-161, 1991.
2. Fischman DL, Leon MB, Baim DS, Schatz RA, Gavage MP,
Penn I, Detre K, Veltri L, Ricci D. Nobuyoshi M, Cleman M,
Heuser R, Almond D. Teirstein PS, Fish RD, Colombo A,
Brinker J, Moses J, Shaknovich A, Hirshfeld J, Baily S, Ellis S,
Rake R, Goldberg S: A randomized comparison of coronary-stent
placement and balloon angioplasty in the treatment of coonary
artery disease. N Engl J Med 331:496-501, 1994.
3. Sermys PW, de Jaegere P, Kiemeneij F, Heyndrickx G , Emanuelsson H, Marco J, Legrand V, Materne P, Belardi J , Sigwart U,
Colombo A, Goy JJ, van den Heuvel P. Delcan J, Morel MA: A
comparison of balloon-expandable-stent implantation with balloon angioplasty in patients with coronary artery disease. N Engl
J Med 331:489-495, 1994.
4. Piana RN, Moscucci M, Cohen DJ, Kugelmass AD, Senerchia C,
Kuntz RE. Baim DS. Palmaz-Schatz stenting for treatment of
focal vein graft stenosis: Immediate results and long-term outcome. J Am Coll Cardiol 23:1296-1304, 1994.
5 . Kuntz RE, Safiaan RD, Levine MJ, Reis GJ, Diver DJ, Baim DS:
Novel approach to the analysis of restenosis after the use of three
new coronary devices. J Am Coll Cardiol 19:1493-1499. 1992.
6. Eigler NL, Weinstock B, Douglas JS, Goldenberg T, Hartzler G,
Holmes D, Leon M, Margolis J, Nobuyoshi M, O'Neill W, Rothbaum D, Roubin G, Untereker W, Cowley M, Forrester J, Litvack F: Excimer laser coronary angioplasty of aorto-ostial
stenoses: Results of the excimer laser coronary angioplasty
16
7.
8.
9.
10.
II.
12.
13.
Rechavia et al.
(ELCA) registry in the first 200 patients. Circulation 88:20492057. 1993.
Fischell TA, Derby G, Tse TM, Stadius MI: Coronary artery
vasoconstriction routinely occurs after percutaneous transluminal
coronary angioplasty. Circulation 78: 1323-1334. 1988.
Haude M. Erbel R. Issa H, Meyer J: Quantitative analysis of
elastic recoil after balloon angioplasty and after intracoronary
implantation of balloon expandable Palmaz-Schatz stents. J Am
Coll Cardiol 21:26-34, 1993.
Rensing BJ, Hermans WRM, Beatt KJ, Laarman GJ, Suryapranata H, Brand M. Feyter PJ, Sermys PW: Quantitative angiographic assessment of elastic recoil after percutaneous transluminal coronary angioplasty. Am J Cardiol 66:1039-1044, 1990.
Hanet C. Wijns W, Michel X, Schrceder E: Influence of balloon
size and stenosis morphology on immediate and delayed elastic
recoil after percutaneous transluminal coronary angioplasty. J Am
Coll Cardiol 18506-51 1 . 1991.
Roubin GS, Douglas JS Jr, King SB, Lin S. Hutchison N .
Thomas RG, Gruentzig AR: Influence of balloon size on initial
success, acute complications, and restenosis after percutaneous
transluminal coronary angioplasty: A prospective randomized
study. Circulation 7837-565, 1988.
Rensing BJ, Hermans WR, Strauss BH, Sermys PW: Regional
differences in elastic recoil after percutaneous transluminal angioplasty: A quantitative angiographic study. J Am Coll Cardiol
17:34B-8B, 1991.
Kimura T, Nasaka H, Yokoi H. lwabuchi M, Nobuyoshi M:
Serial angiographic follow-up after Palmaz-Schatz stent implantation: Comparison with conventional balloon angioplasty . J Am
Coll Cardiol 21:1557-1563, 1993.
14. Gordon PC, Gibson CM. Cohen DJ, Carrozza JP, Kuntz RE,
Baim DS: Mechanisms of restenosis and redilation within coronary stents-uantitative
angiographic assessment. J Am Coll
Cardiol 21:1l66-ll74, 1993.
15. Leon MB, Popma JJ, Fischman DL, Savage MP, Bonner RF.
Kent KM, Goldberg S: Vascular recoil immediately after implantation of tubular slotted metalic coronary stents. J Am Coll Card i d 19:109A, 1992.
16. Popma JJ. White CH. Pinkerton CA, Ramee S, Keller MB, Leon
MB: Effect of balloon expandable stent design on vascular recoil
and lesion-site morphology after intracoronary placement. Circulation 86:1321A. 1993.
17. Kastrati A, Schomig A, Dietz R , Neumann FJ, Richardt G: Time
course of restenosis during the first year after emergency coronary
stenting. Circulation 87: 1498-1505, 1993.
18. Schomig A, Kastrati A, Dietz R, Rauch B, Neumann FJ, Katus
HH, Busch U: Emergency coronary stenting for dissection during
percutaneous transluminal coronary angioplasty: Angiographic
follow-up after stenting and after repeat angioplasty of the stented
segment. J Am Coll Cardiol 23:1053-1060. 1994.
19. Hermans WRM, Rensing BJ, Strauss BH. Sermys PW: Methodological problems related to the quantitative assessment of strech,
elastic recoil, and balloon-artery ratio. Cathet Cardiovasc Diagn
25: 174- 185. 1992.
20. Goldberg SL, Colombo A, Nakamura S, Almagor Y, Maiello L,
Tobis JM: Benefit of intracoronary ultrasound in the deployment
of Palmaz-Schatz stents. J Am Coll Cardiol 24:996-1003, 1994.