Recei ed: 13 July 2022
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Accep ed: 3 Sep embe 2022
DOI: 10.1111/jocs.17027
ORIGINAL ARTICLE
Biomechanical cha ac e is ics o di e en me hods o
neo‐cho dal ixa ion o he papilla y muscles
Luis Fe nández BSc (Hons)
1
|Ampa o Ma ínez Monzonís MD, PhD
2
|
Mohammad M. El‐Dias y MD, PhD
3
|Ca men Ál a ez‐Lo enzo Pha mD, PhD
4
|
Ángel Conchei o Pha mD, PhD
4
|Ángel L. Fe nández MD, PhD
5
1
Depa men o Applied Physics, School o
Physics, Uni e si y o San iago de
Compos ela, San iago, Spain
2
Di ision o Ca diology, Uni e si y Hospi al,
San iago de Compos ela, Spain
3
Di ision o Ca diac Su ge y, Kings on
Gene al Hospi al, Kings on, Canada
4
Depa men o Pha macology, Pha macy, and
Pha maceu ical Technology, Uni e si y o
San iago de Compos ela, San iago, Spain
5
Di ison o Ca diac Su ge y, Depa men
o Su ge y, Uni e si y Hospi al, Uni e si y
o San iago de Compos ela, San iago, Spain
Co espondence
Angel L. Fe nández, MD, PhD, Di ision o
Ca diac Su ge y, Uni e si y Hospi al, A e.
Choupana, s/n. 15706 San iago de
Compos ela, Spain.
Email: [email p o ec ed]
Abs ac
Backg ound and Aim o he S udy: Se e al echniques ha e been desc ibed o neo‐
cho dal ixa ion o he papilla y muscles wi hou any epo ed clinical di e ences.
The objec i e o his s udy is o compa e in i o he biomechanical p ope ies o
ou o hese common echniques.
Me hods: We s udied he biomechanical p ope ies o expanded poly e a luo -
oe hylene neo‐cho dal ixa ion using ou echniques: nonkno ed simple s i ch,
nonkno ed igu e‐o ‐eigh s i ch, kno ed pledge ed ma ess s i ch, and kno ed
pledge ed s i ch using comme cially a ailable p e ab ica ed loops. Neo‐cho dae
we e submi ed o a o al o 20 ac ion‐ elaxa ion cycles wi h inc emen al loads o
1, 2, and 4 N. We calcula ed he elonga ion, he o ce‐s ain cu e, elas ici y, and he
maximum ole a ed load be o e neo‐cho dal ailu e.
Resul s: The elonga ion o he neo‐cho dae was lowes in he simple s i ch ollowed
by he igu e‐o ‐eigh , he pledge ed ma ess, and he comme cially p e ab ica ed
loops (p< .001). Con e sely, he elas ic modulus was highes in he simple s i ch
ollowed by he igu e‐o ‐eigh , he pledge ed ma ess, and he p e ab ica ed loops
(p< .001). The maximum ole a ed load was simila wi h he simple s i ch (28.87 N)
and wi h he igu e‐o ‐eigh s i ch (31.39 N) bu was signi ican ly lowe wi h he
pledge ed ma ess s i ch (20.51 N) and wi h he p e ab ica ed loops (7.78 N).
Conclusion: In i o, neo‐cho dal ixa ion by nonkno ed simple o nonkno ed
igu e‐o ‐eigh s i ches esul ed in less compliance as opposed o he use o kno ed
pledge ed s i ches. Fixa ion echnique seemed o in luence neo‐cho dal bio-
mechanical p ope ies, howe e , i did no seem o a ec he s eng h o he su u e
when subjec ed o loads wi hin physiological anges.
KEYWORDS
cho dal eplacemen , mi al al e epai , poly e a luo oe hylene
J Ca d Su g. 2022;37:4408–4415.4408
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wileyonlinelib a y.com/jou nal/jocs
This is an open access a icle unde he e ms o he C ea i e Commons A ibu ion License, which pe mi s use, dis ibu ion and ep oduc ion in any medium,
p o ided he o iginal wo k is p ope ly ci ed.
© 2022 The Au ho s. Jou nal o Ca diac Su ge y published by Wiley Pe iodicals LLC.
Abb e ia ions: ePTFE, expanded poly e a luo oe hylene; J, Joule; N, New on.
1|INTRODUCTION
Mi al al e epai by using a i icial expanded poly e a luo oe hy-
lene (ePTFE) neo‐cho dae has been p o en o be a sa e and du able
echnique.
1–3
The use o ePTFE neo‐cho dae ei he wi h ee‐hand
echnique o wi h p emeasu ed neo‐cho dae (loop echnique) has
con ibu ed o he inc easing a es o mi al al e epai in pa ien s
wi h degene a i e mi al egu gi a ion.
1–3
The use o ePTFE ma e ial o e s some ad an ages o e o he
ypes o nonabso bable su u e ma e ials. I s so ness, minimal
memo y, and g ea e compliance esul in minimal issue auma
when he kno s ub agains he mi al lea le s su ace. Also, i has a
high esis ance o mechanical s ess and a good pe o mance unde
epea ed ac ion.
4,5
The ePTFE has mic o ine po osi y wi h 50% ai olume and,
he e o e, he diame e o he su u e is educed when subjec ed o
ac ion leading o inc eased s ess.
4,6
On he o he hand, his po ous
mic os uc u e acili a es issue in eg a ion, which can con ibu e o
educing mechanical s ess and inc easing i s du abili y.
7
I is gene ally ecommended o a ach he a i icial neo‐cho dae
o he ib ous po ion o he head o he papilla y muscle o minimize
inju y o he muscle issue. The e a e mul iple s i ching echniques
ha ha e been desc ibed o ancho he ePTFE neo‐cho dae o he
papilla y muscles
8
such using a simple nonkno ed s i ch,
9–11
a igu e‐
o ‐eigh s i ch,
12–14
a ma ess s i ch ein o ced wi h a single
unkno ed pledge
15,16
and a ma ess s i ch ein o ced wi h wo
pledge s kno ed o e he papilla y muscle.
17–20
In i o s udies ha e shown ha bo h he kno ed ma ess s i ch
wi h wo pledge s and he igu e‐o ‐eigh s i ch p o ided adequa e
ensile s eng h wi hin he limi s o no mal physiological ange.
21,22
Howe e , i is possible ha he echnique o ixa ion may also
de e mine o he biomechanical p ope ies o he a i icial neo‐
cho dae such as compliance and igidi y.
The pu pose o his wo k is o s udy in an in i o model he
e ec o he di e en ixa ion echniques on he biomechanical
p ope ies and he pe o mance o ePTFE neo‐cho dae.
2|MATERIALS AND METHODS
Fou neo‐cho dal ixa ion echniques we e s udied; he nonkno ed
simple s i ch, he nonkno ed igu e‐o ‐eigh s i ch, he kno ed
ma ess s i ch wi h wo pledge s, and a pledge ed s i ch using
comme cially a ailable p e ab ica ed ePTFE loops.
Fo he simple and he igu e‐o ‐eigh s i ches, a CV5 ePTFE
su u e (W.L. Go e & Associa es Inc.) was used. Neo‐cho dae o
4.4 cm leng h we e cons uc ed by kno ing a CV‐5 ePTFE su u e on
a 2.8 cm diame e polyp opylene mand el as p e iously desc ibed.
23
Fo he pledge ed ma ess s i ch, a CV5 ePTFE su u e and wo
6 × 5 × 1.5 mm PTFE pledge s we e used. A ma ess s i ch was
pe o med by kno ing wo ePTFE pledge s o e a s eel hook o 3 mm
diame e . The hook was hen emo ed, and a 4.4 cm long neo‐cho da
was c ea ed ollowing simila s eps as desc ibed abo e.
Fo he p emeasu ed loops, comme cially a ailable loops o
24 mm leng h kno ed on he uppe su ace o a PTFE pledge we e
used (Implan Cho dae Loop
®
, San ec GmbH).
A compu e ‐con olled ex u e analyze (TA.TX Plus; S able Mic o
Sys ems L d.) was used o s udy he mechanical p ope ies o he
di e en neo‐cho dal ixa ion con igu a ions. S eel hooks we e ixed o
he uppe and lowe clamps o he ex u e analyze (Figu e 1).
All su u es we e soaked in 0.9% saline o 10 min be o e dynamic
e alua ion which was pe o med a oom empe a u e. Neo‐cho dae
FIGURE 1 (A) Compu e ‐con olled ex u e
analyze . (B) Hooks ixed o he uppe and lowe
clamps o he ex u e analyze
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we e hooked a ound he wo s eel hooks as demons a ed in
Figu e 2. The p e ab ica ed Implan Cho dae Loop
®
was secu ed
wi h a ma ess s i ch on one o he hooks using a second pledge o
suppo he su u e. The dis al end o one o he loops was ixed o
he o he hook by means o a simple s i ch o CV5 ePTFE (Figu e 2).
A o al o 10 neo‐cho dae ixed as a simple s i ch, 10 neo‐
cho dae ixed as a igu e‐o ‐eigh s i ch, 10 neo‐cho dae ancho ed
wi h a pledge ed kno ed ma ess s i ch and 10 p e ab ica ed loops
(Implan Cho dae Loop
®
) we e s udied.
A e moun ing he neo‐cho dae on o he s eel hooks, ac ion‐
elaxa ion cycles we e pe o med by applying hy hmical widening
and na owing o he gap be ween hese hooks The expe imen s
we e ca ied ou unde cycle un il coun mode, which consis ed in
eco ding he o ce‐s ain cu es o he su u e when subjec ed o
uniaxial ension a a a e o 0.5 mm/s un il a maximal p ede e mined
o ce o 1 N o 20 cycles o ac ion‐ elaxa ion ( ideo S1). The same
su u e was u he subjec ed o 20 mo e cycles o ac ion‐ elaxa ion
applying a maximal o ce o 2 N. The same p ocess was inally
epea ed using a o ce o 4 N.
Fo he pu poses o calcula ing he s ain p oduced a each le el
o load, we excluded he eadings om he i s wo ac ion‐
elaxa ion cycles. This is o accoun o he p econdi ioning o he
neo‐cho dae which is de ined as he i e e sible leng hening o he
su u e ha occu s when he kno s a e igh ened due o ac ion.
24
Since each neo‐cho dae consis s o a loop wi h iden ical a ms, i
can be assumed ha he ac ion o ce gene a ed by he ex u e
analyze is equally dis ibu ed o e he wo a ms. The e o e, he
magni udes o o ces applied o each a m we e in ac 0.5, 1, and 2 N,
espec i ely. O no e, hese alues lie wi hin he physiological ange
o loads o which na i e cho ds in he adul human being a e
exposed.
25–27
The a e age maximum elonga ion was calcula ed o e 18 cycles
o ac ion‐ elaxa ion o each o ce magni ude and ixa ion
echnique. The o ce da a we e con e ed o s ess (N/mm
2
) and
he mean elas ic modulus o each o ce and ixa ion me hod was
calcula ed as he slope o he s ess‐s ain cu e.
Finally, neo‐cho dae we e subjec ed o inc easing ensions a a
a e o 0.5 mm/s un il ailu e de ined as su u e up u e o kno
un a eling. The ensile o ce and he elonga ion a ailu e we e
eco ded as well as he ene gy accumula ed du ing ac ion de ined
as he a ea unde he o ce/elonga ion cu e. Maximum esis ance
was also s udied o each o he ou ixa ion echniques.
2.1 |S a is ical analysis
Con inuous a iables a e exp essed as mean alue ± s anda d
de ia ion. S a is ical analysis was pe o med by he R‐S udio
so wa e (RS udio Team [2016]. RS udio: In eg a ed De elopmen
o R. RS udio, Inc.). The no mal dis ibu ion o da a was checked by
he Kolmogo o –Smi no es . One way analysis o a iance
ollowing by Sche é es we e used o de e mine whe he di e -
ences exis ed in he mean alues. A p obabili y alue o less han .05
was conside ed s a is ically signi ican .
3|RESULTS
Du ing each o he ac ion‐ elaxa ion cycles, neo‐cho dal elonga ion
ollowed by sho ening was obse ed in all he ixa ion models.
Elonga ion du ing ac ion was p opo ional o he applied o ce,
howe e , signi ican di e ences we e obse ed be ween he ou
neo‐cho dal ixa ion echniques wi h each o he h ee loads.
Elonga ion was less obse ed wi h he simple s i ch con igu a ion
and p og essi ely inc eased wi h he igu e‐o ‐eigh s i ch, pledge ed
ma ess s i ch and eached i s maximum le el wi h he p e ab i-
ca ed loop.
Table 1shows he mean alues o maximum elonga ion
depending on he ixa ion mode o he neo‐cho dae and he load
applied du ing ac ion.
The mo phology o he o ce‐s ain cu e was simila o he
h ee ensile loads. A mo e linea esponse was obse ed du ing
FIGURE 2 Di e en modes o ixa ion. (A) Nonkno ed simple s i ch. (B) Nonkno ed igu e‐o ‐eigh s i ch. (C) Kno ed ma ess s i ch wi h
wo pledge s. (D) Comme cially p e ab ica ed loop
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ac ion (s e ching) o he neo‐cho dae han du ing eco e y
(sho ening) upon cessa ion o ac ion. This di e ence be ween
o ce/s ain du ing loading e sus unloading ep esen s he mechan-
ical hys e esis. I was also obse ed ha he sepa a ion o he s e ch
cu e om he elaxa ion cu e inc eased p og essi ely om he
simple s i ch o he igu e‐o ‐eigh s i ch o he pledge ed ma ess
s i ch and eached a maximum wi h he p e ab ica ed loop. On he
o he hand, he s e ch‐ elaxa ion cu e showed a endency o
la en om he simple s i ch o he igu e‐o ‐eigh and he pledge ed
s i ches. This shows a p og essi e educ ion in s i ness, wi h he
p e ab ica ed loop being he leas igid and he one wi h he mos
hys e esis. Figu e 3shows he o ce‐s ain cu e o an applied load
o 1 N in he ou neo‐cho dal ixa ion models.
I is obse ed ha o all applied ensile o ces, he elas ic modulus
is g ea e in he simple s i ch and p og essi ely dec eases wi h he
igu e‐o ‐eigh s i ch, he pledge ed ma ess s i ch and he p e ab i-
ca ed loop, wi h he di e ences be ween he ou con igu a ions being
s a is ically signi ican . Table 2shows he alues o he elas ic modulus
o he di e en me hods o neo‐cho dal ixa ion. These indings
indica e ha he s ess sus ained by he su u e is maximum wi h he
simple s i ch due o i s g ea e s i ness and minimum wi h he
p e ab ica ed loop due o i s g ea e compliance.
Rega ding he maximum ole a ed load be o e neo‐cho dal
ailu e, i was obse ed ha all he models could sa ely esis o ces
a leas en imes highe han he physiological ange.
In he simple and igu e‐o ‐eigh models, he mode o neo‐
cho dal ailu e was su u e up u e a he le el o he kno wi hou any
obse ed kno un a eling. In he pledge ed ma ess s i ch, su u e
up u e ook place a he le el o he kno loca ed a he opposi e end
o he pledge s. In e es ingly, wi h he comme cially p e ab ica ed
loop, su u e up u e did no occu , and ailu e was caused by sliding
o he kno ed loops on he PTFE pledge ( ideo S2).
I was ound ha he simple and he igu e‐o ‐eigh s i ches
ole a ed maximum loads highe han he pledge ed ma ess s i ch.
Rega ding he maximum elonga ion alues a he ime o su u e ailu e,
he pledge ed ma ess s i ch p esen ed g ea e elonga ion han he
simple and he igu e‐o ‐eigh s i ches. In he analysis o maximum load,
elonga ion, and abso bed ene gy, he p e ab ica ed loop was no
included because i s mode o ailu e was di e en . Table 3shows he
ensile load alues a he ime o su u e ailu e, su u e elonga ion, and
ene gy accumula ed in he su u e o each o he ixa ion echniques.
Rega ding he ene gy accumula ed in he su u e up o he momen
o up u e, no di e ences we e obse ed be ween he ixa ion me hods.
The o ce‐elonga ion cu e un il su u e ailu e o he p e ab i-
ca ed loop has a special mo phology. I was obse ed ha s a ing a
7 N o ac ion o ce, he kno ed loops slipped o e he PTFE
pledge . Once he ou loops ha e all slipped, i he ac ion
con inues, he su u e up u es a loads o 25–30 N a he le el o
he kno o he CV5 ePTFE su u e used o ix he loop o he hook
( ideo S2). Figu e 4 ep esen s he o ce‐elonga ion ela ionship un il
up u e o each o he di e en ixa ion me hods.
4|DISCUSSION
De e mining he app op ia e heigh is p obably he mos c i ical s ep
o neo‐cho dal implan a ion echniques and i has been he ocus o
many published s udies.
8,28
Va iable echniques ha e been desc ibed
TABLE 1 Value o maximal elonga ion du ing s e ching acco ding o he neo‐cho dal ixa ion echnique and load o ce o ac ion
Maximal elonga ion (%)
Fo ce (N) Simple s i ch Figu e‐o ‐eigh Pledge ed ma ess P e ab ica ed loop p alue
1 N 2.58 ± 0.27 4.4 ± 0.78 6.46 ± 0.88 9.78 ± 2.68 <0.001
a
2 N 3.22 ± 0.28 5.83 ± 1.12 8.66 ± 1.03 12.54 ± 2.7 <0.001
a
4 N 4.09 ± 0.35 7.24 ± 1.13 11.37 ± 0.49 17.23 ± 3.20 <0.001
a
No e: Elonga ion (%). N = maximal load o ce in New on.
a
S a is ically signi ican be ween all ixa ion echniques.
FIGURE 3 A e age o ce‐elonga ion cu e o 18 cycles o
uniaxial loading ( ed)/unloading (blue) o a maximal load o ce o 1 N
in he ou models o neo‐cho dal ixa ion. A: Simple s i ch. B: Figu e‐
o ‐eigh s i ch. C: Pledge ed ma ess s i ch. D: P e ab ica ed loop
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o a ach he neo‐cho dae o he papilla y muscles, howe e , he
di e ences be ween hese echniques ha e no been ho oughly
in es iga ed.
28
Some au ho s sugges ha using a simple nonpledge ed
nonkno ed s i ch allows he wo a ms o he su u e o au oma ically
adjus o equal leng h
10
while o he s sugges ha a pledge ed
nonkno ed U‐s i ch may allow o some adjus men in leng h by he
sliding he o su u e o e he pledge .
16
These wo echniques may
o e an ad an age by equally dis ibu ing he ension on bo h a ms
o he neo‐cho dae.
Some in i o s udies epo ed simila esis ance o up u e
be ween neo‐cho dae ixed by means o a nonkno ed igu e‐o ‐eigh
s i ch and he p e ab ica ed loops kno ed on he su ace o a PTFE
pledge and ancho ed ia a ma ess s i ch ein o ced by a second
pledge .
21
The ad an age o he igu e‐o ‐eigh s i ch could be he
less bu den o o eign ma e ial and he po en ial lowe isk o
in ec i e bac e ial endoca di is.
21
Howe e , o da e no clinical o expe imen al s udies ha e been
published on he e ec o di e en ixa ion echniques on he
biomechanical p ope ies o ePTFE neo‐cho dae. Fo he i s ime,
we s udied in i o he e ec o ou di e en ixa ion echniques on
some biomechanical p ope ies such as elonga ion, s ess, elas ici y,
and esis ance o up u e.
We we e able o demons a e ha he simple and he igu e‐o ‐
eigh s i ches ha e g ea e igidi y, lowe hys e esis, and less
elonga ion despi e ha in heo y hey should allow o some deg ee
o sliding o he su u es on he papilla y muscle and consequen ly a
mo e uni o m dis ibu ion o ension be ween he wo a ms o he
loop.
10,16
On he con a y, he mo e complex ixa ion echniques such as
he pledge ed ma ess s i ch and he p e ab ica ed loop we e ound
o be mo e dis ensible and showed a biomechanical beha io simila
o ha o he na i e cho dae. I has been sugges ed ha his
cha ac e is ics may con ibu e o a highe esis ance o a igue and
up u e.
5,24
Se e al ac o s can explain why he mode o ixa ion may explain
he di e ences in he biomechanical beha io o he neo‐cho dae.
Fi s , in he ma ess s i ch and he p e ab ica ed loop, ac ion is
applied on a g ea e numbe o kno s ha a e also suppo ed on
po ous pledge s. This can esul in he inc ease in he in e nal isco‐
elas ic damping du ing each cycle as well as an inc ease in hys e esis,
a o ing g ea e compliance and less igidi y.
Second, i has been obse ed ha he longe an ePTFE su u e is
subjec ed o uniaxial ac ion he mo e igid i becomes. This inc ease
in s i ness when uniaxial ac ion is applied could be due o a g ea e
in e nal ic ion o ce
5
as well as a possible whipping phenomenon.
29
The simple s ich ep oduces wi h g ea accu acy he uniaxial ac ion
model. On he con a y, in he igu e‐o ‐eigh s i ch and he
pledge ed s iches he ansmission axis o he applied o ce is
modi ied by he di e en h ows o he su u e. This change in he
ac ion axis can po en ially modi y he con o ma ion o he chemical
b idges o he ePTFE, making i mo e complian .
In ela ion o he esis ance o up u e es , all he neo‐cho dal
ixa ion echniques we e s able e en when subjec ed o loads
TABLE 2 Value o mean elas ic modulus acco ding o he neo‐cho dal ixa ion echnique and load o ce o ac ion
Elas ic modulus (N/mm
2
)
Fo ce (N) Simple s i ch Figu e‐o ‐eigh Pledge ed ma ess P e ab ica ed loop p alue
1 N 2867 ± 314 1614 ± 195 974 ± 125 999 ± 77 <0.001
a
,
b
2 N 5148 ± 577 3064 ± 388 1809 ± 175 1713 ± 129 <0.001
a
,
b
4 N 8484 ± 842 5683 ± 677 3276 ± 295 2467 ± 148 <0.001
a
,
b
No e: N = maximal load o ce in New on.
a
S a is ically signi ican when compa ing simple s i ch s. igu e‐o ‐eigh s i ch.
b
S a is ically signi ican when compa ing nonpledge ed s. pledge ed s i ches.
TABLE 3 Value o load o ce, elonga ion, and ene gy a ailu e o each neo‐cho dal ixa ion echnique
Fo ce (N) Simple s i ch Figu e‐o ‐eigh Pledge ed ma ess P e ab ica ed loop p alue
Load (N) 28.87 ± 2.33 31.39 ± 2.48 20.05 ± 1.79 7.78 ± 0.24
a
<0.001
b
Elonga ion (mm) 5.14 ± 0.79 6.53 ± 0.84 10.31 ± 0.5 NA <0.001
b
Ene gy (J) 0.062 ± 0.016 0.069 ± 0.014 0.049 ± 0.005 NA ns
No e: N = load a ailu e in New on. Elonga ion = maximal elonga ion in mm. J = ene gy in Joule.
a
Load o sliding o he kno ed loops on he p e ab ica ed Implan Cho dae Loop
®
b
S a is ically signi ican when compa ing nonpledge ed s. pledge ed s i ches.
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signi ican ly highe han he physiological ange, he e o e hey
seemed o be equally eliable o use.
While in he simple s i ch and he igu e‐o ‐eigh s i ch neo‐
cho dal up u e occu ed a he kno le el, i was obse ed ha in
pledge ed ma ess s i ch up u e occu ed a he le el o kno s loca ed
a he opposi e end o he pledge s. This is in line wi h p e ious indings
ha he dec ease in he diame e o he su u e a he le el o he kno s
as well as he possible change in he con o ma ion o he chemical
b idges o he ePTFE can cause an inc ease in s ess on he kno s,
esul ing in up u e when ac ion is applied.
6,30
I should be no ed ha he simple s i ch and he igu e‐o ‐eigh
s i ch, despi e being less complian , suppo g ea e maximum load un il
up u e han he pledge ed s i ches. This beha io is appa en ly
con adic o y since, in gene al, he highe he s i ness, he g ea e he
possibili ies o a igue and up u e o he ma e ial.
24
To explain his
con adic o y beha io , i is impo an o di e en ia e be ween wo
ypes o he ePTFE su u e up u e; he acu e up u e due o sudden
exposu e o sup a‐physiological loads and he delayed up u e due o
ch onic su u e a igue esul ing om he exposu e o epea ed
physiologicalloads.Ononehand,acu e up u eoccu sinabsenceo
ch onic a igue o he su u e ma e ial and he b eaking s eng h
depends, no only on he ma e ial s i ness, bu also on he symme ical
dis ibu ion o he load and he educ ion in he diame e o he su u e
a he le el o he kno s. On he o he hand, delayed su u e up u e
occu s due o ch onic s ess om epea ed ac ion a physiological
loads. In his case, ch onic su u e a igue may esul in ulne able a eas
o ma e ial mic o ac u es and calci ica ion whe e up u e may occu .
This may explain why, in he long‐ e m, a highe a e o up u e occu s
in he su u es whose con igu a ion en ails inc eased s ess.
In his s udy, su u es we e exposed o acu e sup aphysiological
load wi hou ime o de elop ch onic a igue: The simple and he
igu e‐o ‐eigh su u es esis ed a g ea e maximum load despi e
FIGURE 4 A e age o ce‐displacemen cu e o su u e ailu e. The a ea unde cu e ep esen s accumula ed ene gy. (A) Simple s i ch. (B)
Figu e‐o ‐eigh s i ch. (C) Pledge ed ma ess s i ch. (D) P e ab ica ed loop
FERNÁNDEZ ET AL.
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being mo e igid, p obably because o hei con igu a ion ha
acili a es uniaxial ac ion wi h a mo e uni o m load dis ibu ion,
hus p ese ing he s uc u e o he ePTFE and p o iding i wi h
g ea e maximum esis ance.
Rega ding he p emeasu ed loop, i was obse ed ha s a ing a a
ensile o ce 10 imes highe han he physiological ange, he sliding o
he kno ed loops on he PTFE pledge occu ed. I was also obse ed
ha he su u e g adually elonga ed as he loops we e sliding. In he
o ce‐displacemen cu e, his beha io is ep esen ed as a la line ha
emains cons an un il he ou h and las loop is un ied. I he ac ion
o ce con inued o inc ease, up u e occu ed a he le el o he CV5
ePTFE su u e kno a he opposi e end o he loop.
In ela ion o he mode o neo‐cho dal ixa ion in he ee edge o
he lea le , nume ous echniques ha e also been desc ibed wi hou any
p o en supe io i y o any o hese echniques o e he o he s. Some
au ho s sugges implan ing he neocho ds a he ee edge o he
p olapsed lea le a he si e o maximal p olapse while o he s p e e he
hickened poin o he lea le whe e he o iginal na i e cho d was
a ached.
8,28
Rega ding he kno ing echnique o neo‐cho dal ixa ion
in he eeedgeo helea le , heuseo pe ica dialo ePTFEpledge s
has been desc ibed i he lea le issue seems agile, as well as he use
o clips and polyp opylene s iches o p e en sliding o he ePTFE
kno s.
8,28
Mos au ho s use he igu e‐o ‐eigh o he su geon's kno o
p e en he sliding o he kno s when ying he ePTFE su u e in
he ee‐hand echnique.
8,28
The simple s i ch may be, howe e , mo e
app op ia e oancho hep emeasu edloop o he eeedgeo he
lea le . The objec i e o ou s udy was o assess he biomechanical
beha io o di e en neo‐cho dal ixa ion echniques o he papilla y
muscle, he e o e we elec ed o apply he same ixa ion echnique o
he lea le edge (simple s i ch) o a oid adding mo e con ounding
a iables o he s udy.
5|LIMITATIONS
This s udy has se e al limi a ions.
Fi s , he ixa ion o he su u es o he ex u e analyze was
pe o med on igid componen s ha a e di e en in e ms o
biomechanical p ope ies om papilla y muscles and al e lea le s.
Second, only 20 ac ion‐ elaxa ion cycles we e pe o med,
which does no allow o s udy he long‐ e m beha io o he
di e en models. P e ious expe imen al models demons a ed ha
by inc easing he numbe o ac ion‐ elaxa ion cycles, he ePTFE
ends o become mo e igid.
24
Also, he speed o he ac ion‐
elaxa ion cycles was signi ican ly lowe han ha occu ing du ing
he human ca diac cycle. This di e ence can po en ially esul in
changes in biomechanical beha io as i was sugges ed ha
inc easing he ac ion‐ ela ion speed may lead o mic o ac u es o
he ePTFE which can a ec i s esis ance. Simila ly, he equency o
he ac ion‐ elaxa ion cycles can a ec he beha io and iscoelas ic
p ope ies o ePTFE.
29
Finally, o he calcula ion o he elas ici y modulus, he load
o ce da a we e con e ed o s ess by di iding he applied load o ce
by he ini ial c oss‐sec ional a ea o he su u e, assuming ha he e
we e no changes in he c oss‐sec ional a ea when o ce was applied.
This assump ion was made since all su u es a e made o he same
ma e ial and, he e o e, he change in c oss‐sec ional a ea wi h
ac ion should be consis en among he di e en ixa ion models.
6|CONCLUSIONS
In i o, neo‐cho dal ixa ion o papilla y muscles by means o
nonkno ed simple s i ch o nonkno ed igu e‐o ‐eigh s i ch
esul ed in g ea e igidi y and less compliance as opposed o he
use o kno ed pledge ed s i ches.
A an expe imen al le el, he echnique o ixa ion was shown o
in luence neo‐cho dal biomechanical p ope ies, howe e , i did no
seem o signi ican ly a ec he s eng h o he su u e when subjec ed
o loads wi hin physiological anges.
Mo e clinical and expe imen al s udies a e equi ed o u he
iden i y he mos adequa e neo‐cho dal ixa ion echnique o mi al
al e p olapse epai .
AUTHOR CONTRIBUTIONS
Concep and design: Angel L. Fe nández, Ca men Al a ez‐Lo enzo,
Ampa o Ma ínez. Da a analysis and in e p e a ion: Luis Fe nandez,
Ca men Al a ez‐Lo enzo. D a ing a icle: Ca men Al a ez‐Lo enzo,
Angel L. Fe nández, Angel Conchei o. C i ical e ision o a icle:
Ampa o Ma ínez, Mohammad El‐Dias y, Angel L. Fe nández.
App o al o a icle: Luis Fe nández, Ampa o Ma ínez, Mohammad
El‐Dias y, Ca men Al a ez‐Lo enzo, Angel Conchei o, Angel L.
Fe nández. S a is ics: Luis Fe nandez, Mohammad El‐Dias y.
CONFLICTS OF INTEREST
The au ho s decla e no con lic s o in e es .
ORCID
Ángel L. Fe nández h p://o cid.o g/0000-0003-1307-8221
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SUPPORTING INFORMATION
Addi ional suppo ing in o ma ion can be ound online in he
Suppo ing In o ma ion sec ion a he end o his a icle.
How o ci e his a icle: Fe nández L, Monzonís AM, El‐Dias y
MM, Ál a ez‐Lo enzo C, Conchei o Á, Fe nández ÁL.
Biomechanical cha ac e is ics o di e en me hods o
neo‐cho dal ixa ion o he papilla y muscles. J Ca d Su g.
2022;37:4408‐4415. doi:10.1111/jocs.17027
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