ORI GI N AL ARTI CLE
I n flu e n ce of sh oe h e e l h e igh t on v e n ou s fu n ct ion in y ou n g w om e n
W a gn e r Te de sch i Filh oI; Ca r los Eli Piccin a t oI I; Ta k a ch i M or iy aI I I; Edw a ldo E. Jov ilia n oI V; N e i R. A. D e z ot t iI V
IResident, Vascular Surgery and Angiology, Hospital das Cl€nicas, Faculdade de Medicina de Ribeir•o Preto, Universidade de S•o Paulo (USP), Ribeir•o Preto, SP, Brazil.
IIProfessor and Head of Vascular Surgery and Angiology, Hospital das Cl€nicas, Faculdade de Medicina de Ribeir•o Preto, USP, Ribeir•o Preto, SP, Brazil.
IIIPhysician. Professor, Vascular Surgery and Angiology, Hospital das Cl€nicas, Faculdade de Medicina de Ribeir•o Preto, USP, Ribeir•o Preto, SP, Brazil.
IVPh.D. in Surgery. Assistant physician, Vascular Surgery and Angiology, Hospital das Cl€nicas, Faculdade de Medicina de Ribeir•o Preto, USP, Ribeir•o Preto, SP, Brazil.
Correspondence
J Vasc Bras. 2007;6(4):352-8.
ABSTRACT
Ba ck gr ou n d: The influence of shoe heel height on venous function is still a controversial subject in the international literature. The importance of ergonomics for quality of life is a universally
accepted factor, and situations that impair it, such as prolonged permanence in the supine position, shoe quality and workplace conditions may interfere with the individual’s health.
Obj e ct iv e : To analyze the influence of shoe heel height on lower limb venous drainage using air plethysmography.
M e t h od: Fifteen asymptomatic women with mean age of 24.6 years, wearing shoes of appropriate size were examined in three different situations: barefoot (0 cm), medium heels (3.5 cm) and high heels (7 cm). Body mass index was < 25 and the subjects were classified according to the CEAP International Classification based on clinical (C0 or C1), etiologic (Ep), anatomic (As) and
physiopathological (Pr) criteria. The values of venous filling index (VFI), ejection fraction (EF) and residual volume fraction (RVF) were divided into three categories according to heel height and compared to one another by repeated means analysis of variance (ANOVA).
Re su lt s: EF was decreased and RVF was increased in the high heel group compared to the
barefoot group (p < 0.005). These parameters did not differ between the medium heel group and the other groups. VFI showed a similar behavior in the three situations evaluated.
Ke y w or ds: Plet hy sm ogr aphy , er gonom ics, low er lim bs, v enous insufficiency .
RESU M O
Con t e x t o: A influência da alt ur a do salt o de sapat os na função v enosa é ainda assunt o cont r ov er so
na lit er at ur a m undial. A im por t ância da er gonom ia na qualidade de v ida é um fat or consagr ado e sit uações que a pr ej udiquem com o per m anência pr olongada na posição supina, qualidade dos calçados e condições do local de t r abalho podem int er fer ir na saúde do indiv íduo.
Obj e t iv o: Est udar a influência da alt ur a do salt o do sapat o na dr enagem v enosa dos m em br os
infer ior es, ut ilizando- se a plet ism ogr afia a ar ( PGA) .
M é t odo: Quinze m ulher es, com idade m édia de 24,6 anos, assint om át icas, ut ilizando calçados de
t am anhos apr opr iados, for am ex am inadas em t r ês m om ent os: descalças ( 0 cm ) , salt o m édio ( 3,5 cm ) e alt o ( 7 cm ) . Apr esent av am índice de m assa cor por al < 25 e for am classificadas de acor do com a Classificação I nt er nacional CEAP, em cr it ér ios: clínico ( C0 ou C1) , et iológico ( Ep) , anat ôm ico ( As) e fisiopat ológico ( Pr ) . Os v alor es do índice de enchim ent o v enoso ( I EV) , da fr ação de ej eção ( FE) e da fr ação de v olum e r esidual ( FVR) for am separ ados em t r ês cat egor ias pela alt ur a do salt o e com par ados ent r e si, ut ilizando- se a análise de v ar iância par a m édias r epet idas ( ANOVA) .
Re su lt a dos: Houv e dim inuição da FE e aum ent o da FVR no gr upo de salt o alt o em r elação ao
gr upo descalço ( p < 0,005) . Não ocor r eu difer ença desses par âm et r os ent r e o gr upo de salt o m édio e os out r os gr upos. O I EV com por t ou- se de m aneir a sem elhant e nas t r ês sit uações av aliadas.
Con clu sã o: O salt o alt o dim inui a função de bom ba m uscular dem onst r ado pela queda da FE e
aum ent o da FVR, podendo, com o seu uso cont ínuo, pr ov ocar hiper t ensão v enosa nos m em br os infer ior es, o que poder ia ser pr edit iv o de sint om at ologia na doença v enosa.
Pa la v r a s- ch a v e : Plet ism ogr afia, er gonom ia, m em br os infer ior es, insuficiência v enosa.
I n t r odu ct ion
High heels, w idely used am ong w om en due t o t heir est het ic v alue, is no longer ex clusiv e of special m om ent s and has becom e a daily opt ion in w or k env ir onm ent .
Var iat ions in for m , consist ency and m at er ial used in shoe m anufact ur ing, especially heel height , m ay hav e an influence on w om en's healt h. Volunt eer s t hat w or e soft shoes aft er w ear ing r igid shoe soles had not only m or e r epor t ed com for t , but also r educt ion in edem a and in ank le im pact aft er w ear ing t hem for only 2 hour s.1
Er gonom ics and w or k ing condit ions, w it h r egar d t o post ur e ( sit t ing, st anding and w alk ing) , and t ype of shoes and soil r igidit y influence sy m pt om s of t ir edness, lum bar and plant ar pain. Such com plaint s w er e obj ect iv ely confir m ed based on elect r om y ogr aphic m easur em ent s of t he legs and par av er t ebr al lum bar m uscles and by m eans of pr essur e and im pact sensor s inst alled on shoes.1 - 3
and har dness hav e or t hopedic im plicat ions, such as for m at ion of calcaneal ex ost osis.5 But not ev er y t hing r egar ding low er lim b healt h is lim it ed t o t y pe of shoe, soil char act er ist ic or indiv idual's posit ion: w alk ing speed, w hen incr eased, r aises plant ar pr essur e peak s,6 and biophy sical st r uct ur e also int er fer es w it h com plaint s of pain and fat igue, since t hey ar e m or e com m on in shor t er
indiv iduals or in t hose w it h m or e m ass.7
Despit e t he av ailable k now ledge, t her e is no specific infor m at ion in t he lit er at ur e about t he influence of high- heeled shoes in v enous dr ainage of t he low er lim bs.
Thus, t his st udy aim ed at inv est igat ing t he influence of shoe heel height ( 3.5 and 7 cm ) in v enous dr ainage of t he low er lim bs in y oung w om en in r elat ion t o t he bar e foot posit ion, by using APG.
M e t h od
Fift een asy m pt om at ic w om en aged 20- 30 y ear s w er e st udied ( m ean age = 24.6 y ear s) . They had body m ass index < 25 and w er e classified accor ding t o CEAP I nt er nat ional Classificat ion, used as a st andar d in t he st udy of chr onic v enous disease, in clinical ( C0 or C1) , et iologic ( Ep) , anat om ic ( As) and phy siopat hological ( Pr ) cr it er ia.8
The ex am inat ions w er e per for m ed at t he Labor at or y of Noninv asiv e Vascular I nv est igat ion of t he Cour se of Vascular Sur ger y at Hospit al das Clínicas da Faculdade de Medicina de Ribeir ão Pr et o da Univ er sidade de São Paulo, Br azil, in t he aft er noon and by t w o ex am iner s. Maneuv er s w er e st ar t ed aft er dem onst r at ion of t he ex am inat ion t o t he v olunt eer and aft er gaining her under st anding and t r ust .
APG w as per for m ed in t hr ee m om ent s w it h each v olunt eer : bar e foot ( 0 cm ) , m edium heels ( 3.5 cm ) and high heels ( 7 cm ) . All t he par t icipant s w er e w ear ing shoes of appr opr iat e size and signed a consent t er m appr ov ed by t he Resear ch Et hics Com m it t ee of Hospit al das Clínicas da Faculdade de Medicina de Ribeir ão Pr et o da Univ er sidade de São Paulo, pr ocess no. 15.309/ 2005.
Calf m uscle pum p funct ion w as st udied by APG. The SDV 3000 ( Angiot ec®, Belo Hor izont e, Br azil) device w as used, w it h com put er- aut om at ed calibr at ion.
To per for m t he ex am inat ion, t he labor at or y t em per at ur e w as m aint ained bet w een 22 and 24 º C. An ex am inat ion bed w as used at a height close t o 55 cm t o facilit at e pat ient 's m obilizat ion fr om supine t o or t host at ic posit ion.
APG consist ed of a dev ice connect ed by cables t o a com put er , and a poly ur et hane hose m easur ing 2.5 m in lengt h, connect ed t o a 35- cm cuff and appr ox im at ely 5- L capacit y , m ade of t he sam e m at er ial as t he hose.
The ex am inat ion w as per for m ed w it h t he pat ient in t he supine posit ion for v ein em pt y ing,
m aint aining her leg elev at ed at 45º and slight ly flex ed k nee. The pat ient 's foot w as suppor t ed by t he ank le at a 20- cm height in r elat ion t o t he ex am inat ion t able. A pneum at ic cuff of an
appr opr iat e size w as placed in t he pat ient 's leg, inv olv ing t he w hole leg ex t ension, fr om t he k nee t o t he ank le, w it hout ex ceeding leg lim it s, t hus allow ing a good cont act of t he cuff w it h t he sk in. The lat t er , in it s t ur n, caused m inim al occlusion of super ficial v eins.
Aft er an elect r onic com m and, t he cuff w as aut om at ically inflat ed unt il select ed pr essur e of 6
m m Hg, and t he dat a w er e t r ansm it t ed t o t he pr essur e t r ansducer , locat ed in t he dev ice, am plify ing t he signal and r egist er ing it as a gr aph in t he com put er scr een.
A basal v olum e v alue w as obt ained and t hen t he pat ient w as r equest ed t o r aise her leg aided by t he ex am iner , st anding on t he unassessed lim b. The pat ient placed her hands on a w alk ing dev ice for bet t er balance. I ncr eased leg v olum e w as obser v ed unt il r eaching a plat eau, indicat ing t hat t he v eins w er e full. The differ ence bet w een init ial and plat eau v olum e r epr esent s funct ional v enous v olum e ( VV) .
Nex t , t he pat ient w as r equest ed t o st and on bot h feet and per for m a plant ar flex ion m ov em ent , causing calf m uscle cont r act ur e, r esum ing t hen init ial r est posit ion or r elax at ion of assessed lim b. Decr ease obser v ed in t he gr aph cur v e cor r esponds t o ej ect ed v olum e ( EV) , r esult ing fr om calf m uscle cont r act ion.
Aft er t his m ov em ent , a new plat eau is r eached ( usually m or e elev at ed t han t he init ial plat eau) and t he pat ient w as r equest ed t o per for m 10 m ov em ent s of plant ar flex ion in a v elocit y of one
m ov em ent per second. Decr eased v olum e w as also r ecor ded. Residual v olum e ( RV) w as calculat ed based on final basal v alue in r elat ion t o r em aining v olum e at t he end of m ov em ent s.
Aft er plant ar flex ions w er e ov er , t he pat ient w as r equest ed t o r esum e r est posit ion and r elax assessed lim b unt il r eaching a new v enous filling plat eau. Aft er lev eling, w it h t he aid of t he ex am iner , t he pat ient r et ur ned t o supine posit ion on t he ex am inat ion t able w it h t he foot on t he suppor t , and t ot al lim b em pt y ing w as r ecor ded, show n by a gr aph lev eling cor r esponding t o final v olum e ( FV) .
Volum e/ t im e gr aph is seen on t he com put er scr een. Once t he gr aph w as cr eat ed, m ar k ings using t he soft w ar e cur sor w er e per for m ed, cor r esponding t o init ial v olum e ( ZERO) , v enous v olum e ( VV) , ej ect ed v olum e ( EV) , r efilling v olum e ( ReV) , m inim al r esidual v olum e ( RV m in) and finally final v olum e ( FV) . The soft w ar e aut om at ically m ar k ed t he t im e spent t o r each 90% of v enous v olum e ( 90% VV) (Figur e 1) .
Aft er t he pr ocedur e descr ibed abov e w as finished w it h t he v olunt eer bar e foot , t he sam e r out ine w as r epeat ed w it h t he v olunt eer w ear ing shoes in bot h feet , fir st w it h a 3.5- cm heel and t hen w it h a 7- cm heel, r esult ing in t hr ee gr aphs per v olunt eer . The cuff w as alw ay s placed in t he left leg.
VFI is t he v ar iat ion of v olum e pr oduced in t he lim b div ided by t he cor r esponding t im e in seconds, w hen passing fr om t he supine t o t he or t host at ic posit ion, calculat ed using t he for m ula VFI = 90% x VV / VFT 90 and ex pr essed in m L/ s.
We st udied t he calf pum p funct ion using t he dat a obt ained fr om t he v ar iables EF and RVF.
EF pr ov ides an est im at e of v enous r eflux dur ing phy sical act iv it y and t he changes t hat r esult in less ej ect ed blood. EF is t he per cent age of t ot al v enous v olum e, ej ect ed in a single calf m uscle
cont r act ion. I t is calculat ed by t he for m ula EF = ( EV / VV) x 100, w her e EV is ej ect ed v olum e and VV is v enous v olum e.
RVF is linear ly r elat ed t o out pat ient v enous pr essur e ( OVP) , m easur ing it noninv asiv ely , i.e., m easur ed by t he for m ula RVF = ( RV / VV) x 100, w her e RV is r esidual v olum e.1 0
VFI < 2, EF > 40% and RVF < 35% ar e nor m al v alues in t he lit er at ur e.1 1
To com par e t he v alues of v ar iables VFI , EF and RVF bet w een plain, m edium and high heels, v ar iance analy sis w as used for r epeat ed m easur em ent s ( ANOVA) , consider ing significance lev el of p < 0.05 by Bonfer r oni post hoc t est .1 2
Re su lt s
VFI , EF and RVF v alues w er e div ided int o t hr ee cat egor ies accor ding t o heel height : bar e foot ( 0 cm ) , m edium heels ( 3.5 cm ) and high heels ( 7 cm ) . To facilit at e r eading and under st anding of r esult s, t hose v alues ar e pr esent ed in t ables and figur es. Ther e w as r educt ion in v enous dr ainage dem onst r at ed by EF r educt ion (Figur e 2 and Table 1) and incr ease in RVF (Figur e 3 and Table 2) for t he high- heel gr oup ( 7 cm ) com par ed w it h t he bar e foot gr oup ( 0 cm ) .
D iscu ssion
APG is a m et hod of gr eat v alue in assessing t he v enous sy st em of t he low er lim bs, allow ing clinical and phy siological cor r elat ions.1 3 APG quant ifies v enous v olum e, super ficial and deep v enous r eflux in m L/ s, degr ee of v enous obst r uct ion and ej ect ion capacit y of calf m uscle pum p noninv asiv ely , accor ding t o blood flow gr aphs obt ained dur ing t he m aneuv er s.1 4 Accor ding t o Yang, in addit ion t o t hat infor m at ion, APG can r ev eal elem ent s t hat help t her apeut ic m anagem ent and assess t he effect of t he pr oposed t r eat m ent ,1 5 including by char act er izing hem ody nam ic st udy dur ing use of elast ic com pr ession.1 6
st r engt hening in v enous hem ody nam ics1 8 hav e been obser v ed using APG.
RVF ex pr esses t he com bined effect of v enous r eflux and ej ect ion fr act ion w it h r hy t hm ic ex er cise. I n addit ion, since it is a r elev ant indicat or of out pat ient v enous pr essur e, it w as one of t he par am et er s chosen t o assess t he influence of differ ent shoe heels in v enous hem ody nam ics.1 9
The m ain m echanism of v enous r eflux in t he low er lim bs is blood ej ect ion t hr ough m uscle
cont r act ion. The " calf pum p" is act iv at ed at each st ep, ej ect ing blood against gr av it y and, due t o v enous v alv e com pet ence, t her e is no r eflux .
Ank le m obilit y is an essent ial fact or for an efficient per for m ance of t he calf pum p. When t ibial-t ar sal ank y losis is insibial-t alled, ibial-t her e is ir r ev er sible chr onic v enous insufficiency , because ibial-t he
gem ellus- soleus pum p funct ion is cancelled.2 0 Calf cont r act ion dur ing w alk ing aim s at elev at ing t he body on t ip t oes, im pelling it . Appar ent ly , high heels lim it t his m ov em ent r adically , r educing pum p act ion. The higher t he heels, t he higher t he int ensit y of t his phenom enon.
The degr ee of ank le m obilit y in a nor m al indiv idual is ar ound 70º , 45º due t o plant ar flex ion and 25º due t o dor sal ex t ension. Aft er st udy ing 32 lim bs of 26 m ale adult s, Back et al.2 1 concluded t hat a lim it ed degr ee of ank le m obilit y is a significant fact or in v enous ulcer index. Use of high heels is clear ly not a definit e change, but consider ing " ex posur e t im e," differ ent im pair m ent lev els could occur .
I n t his st udy , t her e w as no differ ence in VFI in t he t hr ee m om ent s ( bar e foot , 3.5- cm heels and 7-cm heels, r espect iv ely ) t est ed, w hich show s t hat global v alv e com pet ence of t he v enous sy st em of low er lim bs w as pr eser v ed dur ing t he t hr ee st ages of t he ex per im ent , a r esult t hat confir m t he select ion cr it er ia of not hav ing v enous disease of any t y pe in assessed w om en.
EF w as r educed w hen v olunt eer s w er e w ear ing high heels, w hich can be ex plained by a low er shor t ening of calf m uscle fiber s dur ing m uscle sy st ole. Consequent ly , blood v olum e r et ained in t he lim b incr eases.
I ncr eased RVF w hen w ear ing high heels ( 7 cm ) found in t his st udy is m ainly due t o higher blood r esidue t hat r em ains in t he lim b aft er EF fall, consider ing t hat RVF is obt ained in m uscle diast ole and r epr esent s t he sum of r esidual v enous v olum e and ar t er ial blood supply com ing t o t he calf.
Despit e t he im possibilit y of confir m ing a significant differ ence bet w een t he m edium- heel gr oup ( 3.5 cm ) and t he ot her gr oups, t her e is a st r ong t endency t o EF r educt ion and RVF incr ease in t his gr oup com par ed w it h t he bar e foot gr oup. I n fur t her st udies, using a lar ger populat ion, such t endency is lik ely t o be cor r obor at ed w it h st at ist ical significance.
We conclude t hat high heels r educed calf m uscle pum p funct ion and t hat it s cont inuous use can cause a st at us of v enous hy per t ension in low er lim bs. That sit uat ion is an essent ial com ponent in v enous disease ev olut ion fr om low er t o higher clinical sev er it y st at es.
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Cor r e spon de n ce : Nei R. A. Dezotti
Faculdade de Medicina de Ribeir•o Preto, Universidade de S•o Paulo Campus USP, Bairro Monte Alegre
CEP 14048-900 – Ribeir•o Preto, SP, Brazil Tel.: (16) 3602.2593
Fax: (16) 3620.1611
Email: neidezotti@yahoo.com.br
This study was carried out at the Course of Vascular Surgery and Angiology, Department of
Surgery and Anatomy, Faculdade de Medicina de Ribeir•o Preto, Universidade de S•o Paulo (USP), Ribeir•o Preto, SP, Brazil. It was presented and received a second place award at the IX
Panamerican Congress on Vascular and Endovascular Surgery, held in Rio de Janeiro, Brazil, from October 31 to November 4, 2006.
