BNH TIM V THAI NGHN

HP VAN NG MCH CH

Hp van ng mch ch (HC) l nguyn nhn thng gp nht gy tc nghn ng tng mu ca tht tri. Cc nguyn nhn khc bao gm hp di van ng mch ch do mng x, hp di van ng mch ch do c tim ph i v hp trn van ng mch ch. Nguyn nhn thng gp nht gy hp van MC ngi trng thnh l vi ho ba l van t chim hoc van ch c hai l bm sinh. Vi ho van MC l bnh l tin trin c trng bi qu tnh lng ng lipid, t chc vim, vi ho rt ging nh x va ng mch. Trong trng hp hp van MC di chng ca thp tim th thng tn thng do dnh cc mp van, so ho, cui cng dn n vi ho l van, hay gp cng cc tn thng khc van hai l do thp.

I. Sinh l bnh

Hp van MC c trng bi qu trnh hp dn l van MC, gy tng dn hu gnh ca tht tri. duy tr cung lng tim, tht tri s bp vi sc bp tm thu cao hn, lm tng p lc ln thnh tim, dn n ph i ng tm tht tri (nh bnh thng ho sc p ln thnh tim theo nh lut Laplace: sc p ln thnh tim = p lc ng knh + 2 dy tim) nhng ng thi li lm gim gin n ca tht tri. Tht tri gin km s lm gim qu trnh y th ng tht tri trong giai on u ca thi k tm trng khin tin gnh tht tri b ph thuc rt nhiu vo s co bp nh tri. Tht tri cng dy ln, lc bp cng gia tng, thi gian tm thu ko di, cng lm tng mc tiu th xy c tim.

Khi suy tim, p lc cui tm trng tht tri tng lm gim p lc ti mu ng mch vnh, gy p cc ng mch nh trong c tim v di ni tm mc, cng lm gim hn na cung cp xy cho c tim trong khi nhu cu vn tng cao, s gy biu hin au ngc v cc triu chng lm sng... Nu van MC hp kht m cung lng tim vn bnh thng th chnh p trung bnh qua van thng ln hn 40mmHg. Tuy nhin, khi suy tim, cung lng tim thp, chnh p qua van v vn tc dng chy qua van cng s thp cho d van MC hp kht. Do vy, mt s bnh nhn hp van MC kht li cha c triu chng trong khi s khc ch hp van MC va c biu hin triu chng. Quyt nh iu tr phu thut thay van MC ch yu da vo s c hay khng c cc triu chng lm sng ch s o nh din tch l van hay chnh p qua van s khng phi l yu t chnh a ra ch nh thay van MC.

II. Cc nguyn nhn gy hp van ng mch ch

Hp van MC bm sinh: dng hp van MC hay gp nht ngi ln l bnh van MC c hai l van, chim 1-2% dn s, ch yu nam gii. Van MC thng thoi ho v vi sm. Mt s dng hp van MC khc cng c th gp nh dnh l van, van mt cnh...

Hp van MC mc phi:

Do thoi ho v vi ho l dng thng gp nht, ni tri tui 70-80. Ri lon chuyn ho canxi trong bnh Paget, bnh thn giai on cui cng lm tng qu trnh vi ho. Cc yu t nguy c ca bnh mch vnh cng thc y nhanh qu trnh vi ho cc l van b thoi ho.

Do thp tim hay km bnh van hai l. Thp tim gy x ho, vi ho, dnh cc l van v mp van MC, dy l van nht l ti b.

III. Din bin t nhin ca bnh

Tin trin ca hp van MC c trng bi mt giai on ko di khng biu hin bt k triu chng c nng no vi t l t vong v t l bin chng rt thp cho ti khi din tch l van MC < 1,0 cm2. Tin trin ca hp van MC do thoi ho v vi van nhanh hn so vi hp van MC bm sinh hoc do di chng thp tim nhng tc tin trin ca hp van MC rt a dng v kh d on: ni chung, vn tc dng chy qua van MC s tng thm 0,3m/sec/nm; chnh p trung bnh qua van MC tng khong 7mmHg/nm v din tch l van gim khong 0,12-0,19 cm2/nm. V th bt buc phi theo di thng xuyn v st sao khi hp van MC nh-va cha c triu chng ng thi tt c bnh nhn hp van MC phi c t vn v tuyn truyn k v cc du hiu tin trin ca bnh.

X cng MC cng c th tin trin thnh hp van MC (van dy m khng c tc nghn ng ra tht tri). X cng MC chim t l khong 25% ngi > 65 tui, lin quan n cc yu t nh tui, gii, ht thuc l, tng huyt p, nng LDL v lipoprotein A, i tho ng X cng MC lm tng 50% nguy c nhi mu c tim v nguy c t vong do nguyn nhn tim mch so vi nhng ngi khng c du hiu ny trn siu m tim, c cho l do qu trnh x va ng mch tim tng, ri lon chc nng ni mc hoc vim h thng hn l do huyt ng hc n thun.

Khi khng c triu chng, t l sng cn gn nh bnh thng: nguy c t t < 2%/nm ngay c khi hp van MC nng nu khng c triu chng c nng. Tuy nhin nu xut hin triu chng c nng, t l sng cn gim xung rt nhanh chng nu khng m: thi gian sng ch khong 2-3 nm do c nguy c t t. t t xy ra bnh nhn hp van MC c triu chng c nng do cc ri lon nhp tht tm tht tri ph i v ri lon chc nng hoc th pht do thiu mu c tim:

Khi bnh nhn c au ngc th t l sng cn ch t 50% sau 5 nm,

Khi c ngt th t l sng cn ch t 50% sau 3 nm,

Khi c suy tim th thi gian sng trung bnh < 2 nm.

Do vy, s xut hin cc triu chng c nng l mt mc rt quan trng trong tin trnh pht trin t nhin ca bnh hp van MC. Tuy nhin cn ch l triu chng kh nhn ra v d b b lc bnh nhn ti khm theo lch.

IV. KHM LM SNG

Nn ngh n hp van MC trc bt k bnh nhn no c ting thi tm thu tng mu b phi pha trn xng c, lan ln ng mch cnh. Phn ln bnh nhn khi i khm cha h c triu chng c nng tuy nhin buc phi hi k pht hin tin s au ngc, chong vng, ngt hoc cc du hiu khc ca suy tim. Tin s hp eo MC gi nguyn nhn hp van MC bm sinh do ch c hai l van, ngc li nu chn on van MC c hai l van, phi o huyt p ng mch t chi loi tr hp eo MC. Tin s thp gi nguyn nhn hp van MC do di chng thp tim.

1. Triu chng c nngThng ch gp khi hp van MC mc nng.

au ngc do tng tiu th xy c tim trong khi cung cp xy cho c tim b gim hoc do x va mch vnh. 25% s bnh nhn khng au ngc c bnh mch vnh, trong khi 40-80% s bnh nhn HC au ngc c km bnh mch vnh.

Chong vng, ngt: do tc nghn c nh ng tng mu tht tri v gim kh nng tng cung lng tim, bnh nhn HC c th tt huyt p nng trong cc tnh hung gim sc cn ngoi vi dn n chong vng hoc ngt.

Biu hin ca suy tim: do ri lon chc nng tm thu hoc chc nng tm trng tht tri v x ho c tim dn dn s dn ti gim co bp. Cc c ch b tr nhm lm tng th tch trong lng mch s lm tng p lc tht tri cui tm trng, tng p lc mao mch phi bt gy huyt phi. Cc tnh trng ri lon y tht tri nh rung nh hoc cn tim nhanh c th gy ra triu chng suy tim r rt.

2. Triu chng thc th

Mch cnh ny yu v tr (pulsus parvus et tardus) l triu chng ni bt, cho php c lng mc hp van MC ngay ti ging. Tuy nhin bnh nhn ln tui do gim chun gin ca thnh mch, bt mch c th vn thy gn ging bnh thng. Mch ngoi vi gim khi HC nng. C th s thy rung miu tm thu khoang lin sn II bn phi v rung miu tm thu dc theo ng mch cnh ( bnh nhn HC kht).

Mm tim p rng, lan ta nu ph i tht tri. Mt s trng hp c th s thy mm tim p p (tng ng vi sng a) hay ting T4 do tht tri gin n km.

Nghe tim: cc ting bnh l chnh bao gm:

Thi tm thu tng mu pha trn bn phi xng c, lan ln c, t cng cao nht vo u-gia tm thu. Mc HC cng nng, ting thi cng di hn, mnh hn v t cc i chm hn (cui k tm thu). Tuy nhin cng ting thi khng lin quan cht vi mc hp do cng ting thi c th gim nh i nu cung lng tim gim nhiu hoc chc nng tht tri gim nng. Trng hp van MC hai l van, cn di ng, c th nghe c ting m van MC trc ting thi tm thu.

Ting T1 ni chung khng thay i khi HC, tuy nhin nu chc nng tm thu tht tri ri lon nng v tng p lc cui tm trng tht tri, m sc T1 s gim do hin tng ng sm v gim lc tc ng ng van hai l. Thnh phn ch ca ting T2 gim i khi HC kht, T2 tr nn nh v gn (n c) do ch nghe thy thnh phn phi ca ting T2. Mt s bnh nhn HC nng c ting T2 tch i nghch thng do thi gian tng mu tht tri qua l van hp kht ko di. T2 tch i nghch thng cng gp trong cc trng hp tc nghn ng tng mu tht tri khc v trong bloc nhnh tri. Ting T3 xut hin khi chc nng tm thu tht tri km. Ting T4 xut hin do nh tri co bp tng mu vo bung tht tri c gin km khi hp van MC kht.

Ngoi ra, c th gp cc ting thi ca h van MC do hp thng i km h van. Hin tng Gallevardin xy ra trong mt s trng hp hp van MC nng, vi ho: thnh phn m sc cao ca ting thi li lan xung mm tim, d ln vi ting thi ca h van hai l km theo.

Nhp tim nhanh lc ngh bnh nhn HC nng l mt trong nhng du hiu u tin ca tnh trng cung lng tim gim thp.

V. Thm d cn lm sng1. in tm

in tm thng c dy nh tri (80%) v ph i tht tri (85%). t khi xy ra ri lon nhp, nu c th ch yu giai on cui v a s l rung nh, nht l khi c km bnh van hai l. C th gp bloc nh tht nu c vim ni tm mc gy bin chng pxe vng van.

2. Chp Xquang ngc

Chp Xquang ngc t c gi tr chn on do hnh nh c th hon ton ging bnh thng. Bng tim c hnh chic ng nu ph i tht tri ng tm. Bng tim thng to khi c ri lon chc nng tht tri hoc c HoC phi hp.

C th gp hnh nh vi ho van MC ngi ln tui (phim nghing) hoc gin on MC ln sau hp.

3. Siu m Doppler tim

Siu m tim c ch nh khi trn lm sng c ting thi tm thu ( 3/6; ting T2 n c hoc cc du hiu gi hp van MC. Siu m Doppler tim l phng php c la chn chn on xc nh v nh gi mc nng ca hp ch. Cc mt ct cnh c (2D hoc TM) l nhng v tr tt nht nh gi c ch, nguyn nhn ca hp van MC v o kch thc bung tim, thnh tim. Siu m tim 2D c tc dng nh gi hnh thi gii phu v chc nng ca van MC, nh gi p ng ca tht tri i vi tnh trng tng gnh p lc. Siu m Doppler cho php nh gi mc hp van MC a s bnh nhn thng qua o vn tc ti a dng chy qua van MC, chnh p trung bnh qua van, din tch l van

Mc hp van MC nh gi bng siu m Doppler c th b thp do t chm tia Doppler khng song song vi hng dng chy qua van MC hay sai s khi o ng knh ng ra tht tri. T l gia vn tc dng mu ng ra tht tri trn vn tc dng mu qua van MC chun li theo kch c ca c th c th thay cho din tch l van: nu l 0,9-1,0 th bnh thng; nu < 0,25 li l hp kht.

Ch nh siu m tim cho bnh nhn hp van MC khi (1) Khng nh chn on hp van MC; nh gi mc hp van MC; nh gi mc dy tht tri, kch thc v chc nng tht tri; (2) nh gi li tnh trng bnh l khi c s thay i/tin trin ca cc triu chng; (3) theo di nh k: hng nm nu hp van MC kht, 1-2nm/ln nu hp van MC va, 3-5nm /ln nu hp van MC nh.

Siu m tim ng thi nh gi kch thc v chc nng tht tri, mc ph i tht tri v cc thng tn van khc phi hp (nu c).

nh gi v tnh trng van MC, nguyn nhn gy hp v nh hng n cc bung tim:

Cc l van dy, m dng vm trong thi k tm thu gp trong HC bm sinh v do thp tim, phn bit bng kiu dy ca l van (mt ct trc di cnh c tri): HC do thp thng dy khu tr b t do nhiu hn so vi thn l van, ng thi rt hay c HHL km theo. Ngc li, HC do thoi ho th qu trnh vi ho thng tin trin t thn cho ti b mp van, lm gim dn di ng l van n gn nh c nh. C th s b nh gi mc HC da vo bin m van trn siu m TM (bnh thng l 16-22 mm): (i) HC nh: bin m van MC t 13-15 mm; (ii) HC va: bin m van MC t 8-12 mm; (iii) HC nng: bin m van MC < 8 mm. Tuy nhin gi tr ny c tnh cht gi , ch khng hon ton chnh xc, v ch nh gi c khong cch gia 2 trong s 3 l van MC. K thut o v v tr mt ct c th lm sai lc kt qu o. Cung lng tim gim nhiu cng lm gim bin m ca van MC d khng c hp van MC thc s.

S lng mp van, ng ng van v hnh dng l van (mt ct trc ngn cnh c tri) cho php chn on cc loi HC bm sinh: van MC c hai l van, van MC dng mt l-mt mp hoc dng mt l-khng c mp van... Tuy nhin, khi van MC vi ho nng th vic xc nh nguyn nhn HC tr nn rt kh khn.

Ph i v gin tht tri, gin nh tri trn mt ct trc di cnh c tri nhng nu hp van MC n thun, tht tri thng nh tuy c ph i. Mt ct bn bung hoc nm bung t mm cho php nh gi chung chc nng co bp v vn ng thnh tht. Cc mt ct ny cng cho php xc nh mc h van MC km theo bng siu m Doppler mu.

nh gi v huyt ng:

Chnh p qua van MC: thng o bng Doppler lin tc s dng mt ct nm bung t mm v mt s mt ct khc nh: khoang lin sn II b phi xng c, trn hm c... da trn cng thc Bernoulli sa i (P = 4 V2) xc nh chnh p trung bnh v chnh p ti a (chnh p tc thi, nh-nh) gia MC v tht tri. Mc HC c phn loi da vo chnh p trung bnh (TB) v ti a (T) qua van MC nh sau:

HC nh: chnh p T < 40mmHg hoc TB < 20 mmHg.

HC va: chnh p T 40-70 mmHg hoc TB 20-40 mmHg.

HC nng: chnh p T > 70 mmHg hoc TB > 40 mmHg.

Mt s yu t lm tng gi to chnh p qua van MC nh: c km h van MC, mng ngn di van MC, tnh trng tng cung lng tim, o sau nht ngoi tm thu, ly nht bp khng i din (khi rung nh) hoc ln vi ph ca h van hai l.

Din tch l van MC: o theo nguyn l ca phng trnh lin tc:

Din tch van MC = r2 VTITT / VTIMC

Trong : VTITT l tch phn vn tc theo thi gian ca dng chy tm thu ti v tr bung tng mu ca tht tri (Doppler xung vi ca s Doppler cch van MC 1 cm ti mt ct 5 bung tim); VTIMC l tch phn vn tc theo thi gian ca dng chy qua v tr van MC b hp; r l bn knh ca bung tng mu tht tri (mt ct trc di, ngay st vng van MC). Mc hp van MC c phn loi da vo din tch l van nh phn phn loi: hp van MC kht khi din tch l van < 1 cm2, c coi l rt kht nu din tch < 0,75 cm2 (< 0,5 cm2/m2 din tch da).

Ch s VTITT/VTIMC: khi < 0,3 tng ng vi hp van MC nng, khi < 0,25 tng ng vi HC kht. Ch s ny khng ph thuc vo lu lng tim v trnh c cc sai st khi o ng knh bung tng mu tht tri, c ch nu hp van MC kht v ri lon chc nng tht tri nng. Tuy nhin, cn lu ch s ny c t l sai st cao khi ng knh bung tng mu tht tri rng > 2,2 cm hoc hp < 1,8cm.

Siu m tim qua thc qun c th o trc tip c din tch l van (2D) cng nh rt c ch nh gi hnh thi van MC trong bnh hp van MC bm sinh.

Siu m gng sc nhm phn bit nhng trng hp hp van MC thc s c ri lon chc nng tm thu tht tri nng (nn chnh p qua van thp) vi nhng trng hp gi hp (bnh l nh hng n c tim t trc, c km hp van MC nh, nn cng ri lon chc nng tm thu tht tri v chnh p thp qua van MC) v trng hp gi hp khng h c ci thin sau khi c m trong khi nguy c phu thut li cao. Khi lm siu m gng sc, truyn Dobutamine vi liu tng dn t 5 n 20 g/kg/pht tng dn cung lng tim, sau dng siu m tim kim tra tng bc din tch l van v chnh p qua van MC. Cn ngng ngay nghim php khi bnh nhn tt p, au ngc hoc xut hin ri lon nhp tim.

4. Thng tim thm d huyt ng

Trc y thng tim l tiu chun vng chn on v lng gi mc hp van MC. Tuy nhin ngy nay, siu m tim dn dn c chp nhn rng ri nh mt phng tin chn on v nh gi hp van MC chnh, thay th cho thng tim.

Trc khi m thay van MC, chp chn lc MV cn c ch nh nhng bnh nhn c nguy c mc bnh MV. Nu cc thng s o c trn siu m tim r rng v tng xng vi bnh cnh lm sng ca mt trng hp hp van MC kht, th ch cn chup MV m khng cn thng tim trc khi m thay van MC. Thng tim phi v tri nh gi huyt ng c ch nh khi nghi ng v mc hp van trn siu m tim hoc khng tng ng gia siu m tim v bnh cnh lm sng. Bnh nhn nam tui > 40 v n tui > 50 cn c chp chn lc MV trc khi m thay van MC.

Khi hp van MC khng kht th phn s tng mu, cung lng tim lc ngh, p lc cc bung tim bn phi v p lc mao mch phi bt u bnh thng. p lc cui tm trng tht tri thng tng do tht tri ph i gim gin. Sng a trn ng cong p lc nh tri, p lc mao mch phi bt thng ni r. Khi mc hp van MC tng ln, p lc cui tm trng tht tri, p lc cc bung tim phi v ng mch phi cng tng ln. Phn s tng mu v cung lng tim s gim khi bnh tin trin n giai on cui. Chnh p qua van MC b hp c tng quan cht ch vi din tch l van MC v dng chy qua van. Do vy khi chc nng tht tri gim nng lm cung lng tim gim nng, th ch thy mc chnh p tng i thp qua van MC cho d c hp kht van MC. Khng th nh gi mc hp van MC nu ch da trn gi tr chnh p qua van n thun m phi ch n chc nng tht tri v mc h van hai l km theo. Mt khc, nu gng sc hoc trong tnh trng cung lng tng, c th o thy mc chnh p ln qua van ngay c khi bnh nhn ch c hp van MC nh. Bi th nh gi y mc hp ca van MC, cn o y v chnh xc dng chy qua van MC, xc nh chnh p trung bnh qua van MC v tnh din tch l van MC hiu dng, nht l nhng bnh nhn c cung lng tim thp hoc c chnh p thp qua van MC.

Gi tr chnh p trung bnh qua van MC o bng thng tim rt ging vi siu m trong khi gi tr chnh p ti a nh-nh o qua thng tim thng thp hn so vi siu m. C th kch thch bng cch truyn Nitroprusside tnh mch nh gi s thay i v chnh p qua van v din tch l van mi khi thay i cung lng tim nhm phn bit cc trng hp hp van MC thc s vi nhng trng hp gi hp.

Cn cn nhc gia cc li ch ca thng tim v nguy c bin chng nht l bnh nhn hp van MC kht. Nguy c t vong sau thng tim bnh nhn hp kht van MC l 0,2%. Bnh nhn hp van MC nng nn dng thuc cn quang loi trng lng phn t thp, khng ionic hn ch bt cc nguy c tt huyt p do gin mch ngoi vi, ri lon nhp chm, ri lon chc nng c tim thong qua, hn ch tc dng li tiu thm thu, nh gim bt nguy c ca th thut. i vi bnh nhn hp kht van MC, nn trnh chp bung tht tri.

Ch nh thng tim thm d huyt ng khi (1) hp van MC chun b m thay van, c nguy c mc bnh ng mh vnh; (2) hp van MC d kin lm phu thut Ross (ghp van MP t thn) m khng nh gi c v tr xut pht ca MV thng qua cc bin php thm d khng chy mu khc v (3) hp van MC khi khng th nh gi r rng hoc khi c s khc bit gia bnh cnh lm sng v cc bin php thm d khng chy mu. Khng ch nh thng tim bnh nhn khng c triu chng hoc khi cc bin php thm d khng chy mu r v tng xng vi bnh cnh lm sng ca bnh nhn.

VI. Hp van MC c chnh p thp- lu lng thp qua van MC

Bnh nhn hp van MC kht nhng cung lng tim thp thng ch c chnh p qua van MC tng i thp (chnh p trung bnh qua van < 30 mmHg). Khi s rt kh phn bit vi nhm ch hp van MC t nh-va c cung lng tim thp. nhm bnh nhn hp van MC nh-va km cung lng tim thp, ri lon chc nng co bp tht tri t trc l nguyn nhn gy gim phn s tng mu v th tch tng mu, tnh trng ny s cng nng hn do gim lc m van MC v cc l van hp r v hn ch vn ng. Vi c hai nhm ny, tnh trng lu lng thp v chnh p thp qua van MC u nh hng n vic tnh din tch l van hiu dng khin c hai trng hp u ch c din tch l van rt nh, tng ng vi hp van MC kht. Mt s phng php nh gi mc nng ca hp van MC c lp vi dng chy qua van nh tnh sc cn van hoc hao ht cng tng mu (stroke work loss) li khng tng xng vi triu chng lm sng nn t c ng dng rng ri.

Nhng bnh nhn hp van MC c chnh p thp-lu lng thp qua van MC c ri lon chc nng tht tri rt cn phi c xc nh chnh p qua van ri tnh din tch qua van trong lc ngh ngi, so vi lc gng sc vi mc ch xc nh xem mc hp l thc s kht hay ch mc t nh-va. Nu tng th tch tng mu v din tch l van tng thm 0,2 cm2 khi truyn dobutamine trong khi thay i rt t chnh p qua van th mc hp van l khng nhiu v nhng kt qu lc ngh nh gi qu mc hp van MC. Ngc li, nhng bnh nhn hp van MC kht s biu hin din tch l van c nh trong khi c tng th tch tng mu v tng chnh p qua van. Bnh nhn no khng tng ng k th tch tng mu (< 20%) s c tin lng rt ti d phu thut hay iu tr ni khoa.

Bnh nhn hp van MC c lu lng thp-chnh p thp qua van MC v ri lon chc nng co bp tht tri c ch nh lm siu m gng sc vi Dobutamine liu thp hoc thng tim thm d huyt ng khi truyn Dobutamine li thp nh gi song phi theo di ht sc cn thn ti cc trung tm c nhiu kinh nghim.

Nghim php gng sc

Nghim php gng sc bnh nhn ngi ln hp van MC khng h chnh xc nh gi bnh MV phi hp do in tim lc ngh bt thng do ph i tht tri v gim d tr vnh. Biu hin ST chnh xung trn in tim khi lm nghim php gng sc gp ti 80% cc bnh nhn hp van MC khng c triu chng, v hon ton khng c ngha tin lng g nh k.

Nghim php gng sc khng c ch nh nhng bnh nhn hp van MC c triu chng do nguy c xy ra bin chng cao: tuy nhin i vi cc bnh nhn cha c triu chng c nng, nghim php gng sc tng i an ton v c th cung cp thm nhng thng tin m khm lm sng ban u cha pht hin ra. Nu tin s bnh khng r rng th nghim php gng sc c th xc nh c kh nng gng sc, cc p ng bt thng v huyt p hoc thm ch cc triu chng ch xy ra khi gng sc. Huyt p tt hoc khng tng khi gng sc bnh nhn hp van MC kht l nhng du hiu tin lng ti.

Nghim php gng sc nhng bnh nhn khng c triu chng ch nn c thc hin di s gim st cht ch ca cc bc s chuyn khoa c kinh nghim, theo di st v in tim v huyt p.

VII. PHN LOI

Phn loi mc hp van ng mch ch da trn c s cc thng s huyt ng nh vn tc dng mu qua van MC (m/sec), chnh p trung bnh qua van MC (mmHg) v din tch l van (cm2) c trnh by trong bng 1. i vi cc trng hp hp van MC nng m cung lng tim cn trong gii hn bnh thng th chnh p trung bnh qua van MC ni chung s ln hn 40mmHg. Tuy nhin khi tim suy, cung lng tim gim th d hp van MC nng, chnh p trung bnh qua van MC v vn tc dng mu qua van li khng cao. Cc thng s huyt ng ny ch mang tnh cht tng i v khng phi l yu t ch yu quyt nh phng hng iu tr ph hp.

Mc hp van ng mch ch

Ch s huyt ngNh Va Kht

Vn tc dng mu qua van MC (m/sec)< 3,03,0 - 4,0> 4,0

Chnh p trung bnh qua van MC (mmHg)< 2525 40> 40

Din tch l van (cm2)> 1,51,0 - 1,5< 1,0

Ch s din tch l van (cm2/m2)< 0,6

VIII. iu tr

Ct li ca iu tr hp van MC nng l phu thut thay van MC. Ni chung phu thut u tin cho nhng bnh nhn c triu chng c nng, do phu thut thay van MC c nguy c bin chng kh cao v t l sng cn ch thc s ci thin r rt khi bnh nhn bc l triu chng c nng. Khi hp van MC ti mc nng, th triu chng c xu hng xut hin v phi m thay van ch trong vng 3 nm. Bnh nhn ln tui hp kht van MC th vic m sm khi cha c triu chng c li hn so vi vic ch i n khi xut hin triu chng c nng. M sm cng c li i vi nhng bnh nhn tr m chnh p qua van MC rt cao v hn ch c nguy c cao t t. Nu bnh nhn c din tch l van MC 1,0 cm2 km theo hp ng k MV th nn m thay van MC phi hp vi bc cu ni ch vnh.

1. iu tr ni khoa

Bt buc phi iu tr khng sinh d phng vim ni tm mc nhim khun cho mi bnh nhn hp van MC khi lm cc th thut c nguy c. Cn iu tr phng thp th pht nhng bnh nhn hp van MC do thp. Bnh nhn hp van MC c tng huyt p th khi iu tr thuc h huyt p phi iu chnh liu v phi hp thuc ht sc thn trng. Ngoi nhng ny, chng h c phc iu tr ni khoa c th no i vi bnh hp van MC khng c triu chng lm sng. Nu bnh nhn c triu chng c nng th phi phu thut thay van ch khng phi l iu tr ni khoa.

Khng hn ch hot ng th lc nu hp van MC nh cha c triu chng, k c thi u th thao. Bnh nhn hp van MC va-kht nn trnh cc hot ng th thao mang tnh i khng c lin quan n vn c ln. Cc dng hot ng khc vn c th thc hin bnh thng, nhng cn lm nghim php gng sc trc nh gi mc gng sc ph hp.

Bnh nhn cha c triu chng c nng (din tch l van MC > 1,0 cm2) th iu tr c mc ch thay i cc yu t nguy c, phng tin pht bnh l ng mch vnh, duy tr nhp xoang v khng ch huyt p. Tt c bnh nhn phi c t vn v hng dn k v cc du hiu v triu chng ca au tht ngc, ngt hoc suy tim i khm li ngay v xt m nu xut hin cc triu chng c nng ny, v khi nguy c phu thut thp hn cc nguy c ca vic tip tc iu tr ni khoa.

iu tr suy tim nhm vo vic kim sot cn bng dch gim huyt phi, thng ch bng thuc li tiu. Tuy nhin, cung lng tim bnh nhn HC nng ph thuc nhiu vo tin gnh, nn cn rt thn trng, trnh dng li tiu liu qu cao, gy tt huyt p (do gim cung lng tim) v gim ti mu ngoi vi. Trnh dng cc thuc nhm Nitrates bnh nhn suy tim do HC nng v thuc lm gim ng k tin gnh, c th gy gim ti mu no v ngt. Digoxin thng ch c ch nh cho bnh nhn HC c suy tim nht l khi rung nh. iu tr HC c suy tim bng thuc khng h ci thin tin lng sng ca bnh nhn. Hn na, iu tr ni khoa tch cc bnh nhn hp van MC nng ri lon chc nng tht tri khng h c li m cn nguy him.

Trnh dng cc thuc gin mch cho bnh nhn hp ch n thun.

Trong mt s bnh cnh hp h van MC, HC phi hp h van hai l, HC phi hp bnh mch vnh th c th cn nhc vic dng cc thuc gin mch song nn ht sc thn trng. Trn l thuyt, bnh nhn h van nhiu s c li khi dng thuc gin mch; bnh nhn c bnh mch vnh cng c li v gim hu gnh s lm gim nhu cu xy c tim. D vy, thuc gin mch ch l bin php iu tr tm thi trc khi m lm cu ni ch vnh.

Liu khi u nn dng rt thp ti phng hi sc (tt nht l nitroprusside d chnh liu), sau khi n nh liu gin mch s chuyn dn sang thuc ung (c ch men chuyn, Hydralazine).

Bnh nhn hp van MC nng chu ng rt km tnh trng rung nh (v tin gnh tht tri ph thuc rt nhiu vo co bp nh). Rung nh nhanh chng v d dng gy gim cung lng tim v huyt phi, ng thi tng nhu cu xy (do nhp nhanh). Bi vy, cn iu tr tch cc rung nh ngay t lc mi khi pht bnh nhn HC nng nhm chuyn v nhp xoang.

Ch nh t bng ngc dng trong ng mch ch (IABP): nhm n nh tm thi tnh trng huyt ng bnh nhn hp van ng mch ch nng, suy tim mt b chun b m. Hiu qu ca t bng trong ng mch ch ch tng ti mu mch vnh trong k tm trng, lm gim tnh trng thiu mu ca ton th c tim khi hp van MC kht, suy tim mt b.

2. Nong van MC bng bng

Nong van MC bng bng qua da rt c ch trong iu tr hp van MC bm sinh tui thanh thiu nin, song tc dng li rt hn ch nhng bnh nhn tui trng thnh v khng th thay th c phu thut thay van MC.

Nong van MC bng bng c th lm gim va chnh p qua van MC, nhng din tch l van sau nong t khi vt qua 1,0 cm2. Bn cnh , t l gp cc bin chng cp/nng kh cao ln ti >10% ng thi ti hp v triu chng lm sng s li nng ln ch trong vng 6-12 thng. T l t vong ca th thut ny khong 2-5%. Nong van MC bng bng ch c ch nh trong mt s trng hp nht nh nh: hp van MC bm sinh tr em, bnh nhn khng th m do tui cao hay c bnh phi hp, iu tr tm thi trc khi m c chun b, iu tr th bnh nhn c ri lon chc nng tht tri nng (xem liu bnh nhn c ci thin sau m hay khng).

Ch nh iu tr tm thi bng nong van MC bng bng bnh nhn hp van MC cng cn cn nhc k. a s bnh nhn hp van MC kht cha c triu chng c nng nu c mt bnh l ngoi khoa khc (khng phi tim mch) u c th phu thut thay van cp cu vi nguy c tng i thp nu theo di st v m bo cn bng dch trong lc gy m v sau m. Nh vy i vi nhm bnh nhn ny khng c ch nh nong van MC tm thi bng bng. Nu thc s cn phi gii quyt hp van MC th bnh nhn nn c m thay van MC trc.

3. Phu thut

i vi hp van MC kht, van vi, c triu chng lm sng, bnh nhn tui trng thnh, phu thut thay van MC l bin php iu tr duy nht c hiu qu. Thay van ng mch ch c a chung hn m sa van v nu ch sa, sau khi gt mng v ly vi l van, cc l van hay b co rt, gy h van ngay sau phu thut v dn dn mc h s tng ln sau m. Tuy nhin, nu bnh nhn tr tui hn, b hp van MC bm sinh hoc do di chng thp tim, van cha vi th vn c th sa van MC. M thay van MC n thun khng km bnh mch vnh hoc cc bnh nng khc th t l t vong quanh phu thut ch khong 2-3%. T l sng cn sau m thay van MC vo khong 85% sau 10 nm.

La chn loi van MC thay ph thuc vo rt nhiu yu t nh tui, nguy c khi dng/khng dng thuc chng ng, c im gii phu, chc nng tht tri, mc hot ng th lc, d tnh m li... Ni chung, phu thut bao gm cc loi:

Phu thut Ross (ghp van t thn): van v thn ng mch phi c ct lun c khi ri thay vo v tr ca van ng mch ch ng thi cm li hai ng mch vnh. Ch van ng mch phi b ct s c thay th bng mt van ng mch phi ng loi. Van ghp t thn kiu ny rt tt v huyt ng, khng cn dng thuc chng ng, t vi ho hn so vi cc van sinh hc khc, c th ln ln theo pht trin ca c th, c c tnh chng nhim trng rt cao nn rt ph hp lm tr nh hoc bnh nhn vim ni tm mc nhim khun song i hi k thut cao v thi gian ko di, d gy ra nhiu ri lon sau m. Tin lng lu di li ph thuc vo mc h van ng mch ch, bnh l van ng mch phi (h, hp) hay cc ri lon chc nng tht phi (th pht sau bnh van MP).

Thay van MC ng loi: c dng rng ri cc bnh nhn tr tui do c im huyt ng tt v khng cn dng thuc chng ng. Tuy nhin theo thi gian, cc van loi ny khng h ln ln, s b thoi ho, vi v gy h. Bn thn k thut thay van loi ny cng kh phc tp v thng phi hp vi vic to hnh mt phn gc ng mch ch v cm li ng mch vnh, cho d vn n gin hn so vi phu thut Ross. Tui th trung bnh ca van l 15 nm. Phu thut ny c t l nhim trng rt t khi ang c vim ni tm mc nn c ch nh khi vim ni tm mc nhim khun trn van nhn to.

Thay van sinh hc (d loi): thng c ch nh cho bnh nhn tui > 70. Trong vng 10 nm, 80-90% van s thoi ho gy h hoc hp do thng l van, gim vn ng, r quanh chn van. Khng cn dng chng ng lu di sau thay van v nguy c huyt khi thp. Phn ln bnh nhn u c chnh p qua van ngay sau m (v b cn tr mt phn do vng van, khung ) mc nhiu hn so vi van c hc v th cn chn loi van c kch thc ln nht (nu c) khi thay gim bt chnh p qua van.

Thay van c hc: cc loi van thng dng l St. Jude Medical, Metronic-Hall v Carbomedics. Bnh nhn sau thay van loi ny phi ung thuc chng ng gim nguy c to huyt khi van v cc bin chng tc mch khc. bn ca loi van ny l cao nht nu duy tr c iu tr chng ng v d phng khng sinh cn thn trong nhiu nm.

Bin chng tim tng sau m thay van MC thng l h hng cu trc van, ri lon hot ng (huyt ng) van, huyt khi kt van, tc mch, chy mu do dng thuc chng ng, vim ni tm mc nhim khun trn van MC nhn to, huyt tn v bloc nh tht. Phi dng thuc chng ng cn thn (i vi bnh nhn no c ch nh) v phi dng ko di sut thi gian tn ti van nhn to (n c i). Bnh nhn hot ng th lc mc thp s t nh hng hn n huyt ng ca van v do tc thoi ho van cng s chm hnThng thng, ch nh m thay van MC khi (1) bnh nhn c triu chng c nng (nh au ngc, ngt, suy tim); (2) nhm bnh nhn cha c triu chng c nng nhng p ng bt thng vi gng sc (xut hin triu chng lm sng hoc c tt huyt p) hay khi c km theo cc yu t khc nh: (3) cn lm th thut/phu thut ln, c nguy c cao hoc c ch nh bc cu ni ch vnh, cn phu thut ng mch ch hoc cc van tim khc; (4) c ri lon chc nng tm thu tht tri (phn s tng mu tht tri di 50%; hoc (5) bnh nhn tui tr v hp van MC rt kht (chnh p qua van MC > 100 mmHg, din tch l van < 0.6cm2; chnh p trung bnh > 60 mmHg, vn tc dng mu qua van MC > 5.0 m/sec).4. iu tr cc trng hp hp van MC

4.1. Hp van MC c triu chng lm sng

Nu hp van MC c triu chng lm sng, thay van MC s ci thin cc triu chng v ci thin tin lng sng r rt. Kt qu tt do phu thut em li ph thuc mt phn ln vo chc nng ca tht tri. Phn s tng mu tht tri gim bnh nhn hp van MC ch yu l do hu ti tng qu mc nn s khi phc/ci thin r sau m thay van. Ngay c nu chc nng tht tri gim do nguyn nhn khc, th tht tri cng hi phc tt sau m thay van, d khng hon ton. Do vy nu khng c nhng bnh nng phi hp khc, thay van MC c ch nh gn nh tuyt i mi bnh nhn hp van MC kht c triu chng. Tui khng phi l yu t chng ch nh ca phu thut do tin lng sau m nhm bnh nhn cao tui cng tng ng vi nhm bnh thng. Thay van MC cn c tin hnh ngay khi xut hin cc triu chng do t t c nguy c xy ra k c trong thi gian ch i.

4.2. Hp van MC cha c triu chng lm sng

Thay van MC c t l t vong chung khong 3-4% (thay van n thun) hoc 5,5-6,8% (thay van kt hp vi m bc cu ch vnh); t l t vong tng ln khong 8,8% vi bnh nhn trn 65 tui. Mt khc, d van nhn to sinh hc th h mi c bn kh hn; thay van MC ngi tr tui vn c nguy c thoi hoi dn n hng van sinh hc hoc nguy c t vong v bin chng nht nh i vi van c hc. Do vy cn cn nhc nhiu kha cnh gia nguy c t vong khi phu thut ngi gi, nguy c bin chng ca van nhn to ngi tr v kh nng t t (< 1%/nm) nu khng phu thut.

Nu hp van MC nng khng c triu chng, kh nng bnh nhn duy tr tnh trng khng c triu chng tim mch < 50% trong vng 5 nm. Tin trin s nhanh hn khi bnh nhn trn 50 tui, van vi ho nng hoc c km bnh MV. Bin c xu thng xut hin nhng bnh nhn huyt ng xu i nhanh v d vn tc dng chy qua MC tng > 0.3m/sec/nm hoc din tch l van MC gim hn 0.1cm2/nm. Biu hin ph i tht tri trn in tim v din tch l van nh i trn siu m Doppler tim l yu t tin lng s xut hin v tin trin ca cc triu chng c nng. Nng BNP trong huyt thanh cng l mt yu t tin lng nng. Nhng nhm bnh nhn ni trn l nhm nguy c cao, c th xy ra cc bin c xu d cha c triu chng, do vy cn theo di st sao hn bng siu m tim cng nh cn nhc ch nh m thay van MC sm.

4.3. Hp van MC cn phu thut bc cu ni ch vnh hoc phu thut tim khc

Bnh nhn hp van MC kht, d c hay khng c triu chng, nu cn phu thut bc cu ni ch vnh (do bnh MV) cng nn thay van MC cng thi im khi phu thut bc cu ni ch vnh. Tng t nh vy, bnh nhn hp van MC kht nu cn phu thut trn mt van tim khc (v d sa van hai l) hoc to hnh gc MC cng cn thay van MC lun khi phu thut. i vi nhng bnh nhn hp van MC v cn m bc cu ni ch vnh, thng vn c ch nh m thay van MC ng thi. Tuy nhin i vi hp van MC nh khng c ch nh thay van MC ng thi vi cc phu thut tim khc.

4.4. Hp van MC ngi cao tui

i vi bnh nhn hp van MC c triu chng, lun lun phi ngh ti phu thut thay van MC k c ngi cao tui do iu tr ni khoa khng h hiu qu cn nong van MC bng bng th hiu qu cha so snh c vi phu thut. V k thut, phu thut thay van MC c th thc hin c bt k la tui no song quyt nh phu thut li ph thuc vo rt nhiu yu t. Nu h MV bnh thng v chc nng tm thu tht tri cn tt th tin lng s tt hn hn nhm c bnh MV hoc ri lon chc nng tht tri, cha k ti s c mt ca nhng bnh l khc. Bnh nhn hn ch hot ng th lc trc m thng cng khng th tr thnh ngi hot ng tch cc sau m. i vi bnh nhn cao tui, ngoi kh nng xut hin cc bin c MV hoc t qu, cn cn tnh n mt s vn khc nh: nu hp ng ra tht tri v ng knh vng van MC nh hay gp bnh nhn n cao tui s phi m rng vng van MC trong m; nu vi ho nng n t chc l van, vng van v gc MC s phi ly b trong m; ph i tht tri qu mc (do hp van MC) u lm tng nguy c t vong v bin chng chu phu do vy phi nh gi v x l ph hp trc, trong v ngay sau m lm gim cc nguy c ny.

4.5. iu tr ni khoa cho nhng bnh nhn khng th phu thut c

Trong mt s tnh hung nht nh, khng th thc hin c phu thut thay van MC v d nh khi c nhiu bnh phi hp (ung th) Trong hon cnh , khng h c bin php iu tr no kh d ko di tin lng sng ca bnh nhn m ch c th ci thin phn no cc triu chng c nng. Bnh nhn biu hin huyt phi c th iu tr bng thuc tr tim digitalis, li tiu v c ch men chuyn song phi iu chnh liu v phi hp thuc rt thn trng. Bnh nhn c cn ph phi cp do hp van MC, c th truyn nitroprusside lm gim huyt phi v ci thin hot ng ca tht tri song phi theo di tht st huyt ng (trong lng mch) ti cc n v iu tr tch cc. Rung nh s nh hng rt xu n chc nng bm mu ca nh tri v tn s tht o nn chuyn nhp bng sc in hoc nu khng thnh cng th bt buc phi kim sot tn s tht bng thuc chng lon nhp. IX. Theo di

Bnh nhn hp van ng mch ch khi cha c triu chng c nng nn c gii thch k v tin trnh ca bnh, theo di st v hng dn ti khm ngay khi c bt k triu chng c nng no nh gim dung np gng sc, au ngc khi gng sc, kh th, chong, ngt Mi ln ti khm, bnh nhn cn c hi k li v triu chng c nng (bnh s), khm lm sng chi tit kt hp vi siu m tim hay nghim php gng sc (nu cn).

Bnh nhn hp van MC kht cn c theo di bng siu m tim mi nm/ln hoc khi c biu hin thay i hay tin trin ca cc triu chng c nng. Nu hp van MC va th cn theo di bng siu m tim 1-2 nm/ln v ch cn theo di 3-5 nm/ln vi bnh nhn hp van MC nh.

Bnh nhn thay van MC cn c lm siu m Doppler tim sau m 1-6 tun nh gi hot ng ca van v chnh p qua van nhn to, lm mc theo di. Sau bnh nhn cn c theo di v kim tra bng siu m tim nh k 6 thng-1nm/ln. Nu thay van c hc, bnh nhn cn c kim tra hiu qu chng ng mu (bng t l prothrombin, INR) nh k iu chnh liu ph hp: vi van MC c hc n thun th nn duy tr INR t 2 n 3, nu c c van hai l c hc (hai van c hc) th nn duy tr INR t 3 n 4,5 (tham kho thm bi van nhn to).

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