Neşe Tuncer, M.D.* / Nazire Afşar, M.D.* / Bahadır D ağ deviren, M.D.**
Ayşe Ö ze rg in , M.D.** / Sevinç A k ta n , M.D.*
*
D e p artm en t o f neurology, S chool o f M edicine, Marmara University, Istanbul, Turkey.
* *D e p artm en t o f Cardiology, Siyam i Ersek Thoracic, C ardiovascular Surgery Center,
İstanbul, Turkey.
ABSTRACT
Objective:
A p p ro x im a te ly 2 0 % of all Ischem ic strokes are the result of an e m b o lu s originating from the heart. T ra n s th o ra c ic e c h o c a rd io g ra p h y (TTE) has long been used to e v a lu a te the cardiac source of em boli but re cently tra n se so p h a g e a l e c h o ca rd io g ra p h y (TE E ), w hich has h igher yield for d e tecting left atrium , a o rtic arch and left atrial app e n d a g e lesions, Is re c o m m e n d e d fo r the asse ssm e n t of p a tients w ith clinical risk factors fo r c a rd io e m b o lism or u n e xp la in e d stroke.Methods:
In this study, the d ia g n o s tic yield of TTE and TE E fo r d e te c tin g potentia l ca rd ia c sources of the e m b o lu s w as co m p a re d in 46 co nsecutive p a tie n ts (26 m en and 20 w om en, aged 23-84 years) w ith tra n s ie n t isch e m ic attack (TIA) or acute isch e m ic stroke.Results:
T T E re v e a le d a p o te n tia l c a rd ia c source of e m bolism in 12 (26% ) patients, all of w hom had clinical e v id e n c e of h e a rt disease, T E E d e te c te d p o te n tia l c a rd ia c s o u rc e s of em bolism in 32 (69% ) p a tie n ts; 7 (21% ) of these had no clinical e vid e n ce of h e a rt disease.Conclusion:
T E E is a s u p e rio r te c h n iq u e to TT E fo r identifying potentia l ca rd ia c so u rce of the e m bolus and sh ould be re c o m m e n d e d fo r earlym a n a g e m e n t and p re ve n tio n of fu rth e r stro ke in p a tie n ts w ith u n d e rly in g h e a rt d is e a s e or une xp la in e d c e re b ro v a s c u la r accident.
Key W ords:
Isch e m ic stroke, T ra n s th o ra c ic e c h o c a rd io g ra p h y , T ra n s e s o p h a g e a l e ch o c a rd io g ra p h y , C a rd ia c so u rce of em b o lism .IN T R O D U C T IO N
Ischem ic stroke is a m a jo r ca u se of m o rb id ity and m ortality. A p p ro x im a te ly 2 0 % of all isc h e m ic stro ke s are the result o f the o b s tru c tio n of a blood vessel by an e m b o lu s o rig in a tin g from the heart (1,2). F ollow ing a rtery to a rte ry e m b o lis m , arising from e xtra cra n ia l la rg e a rte ry a th e ro scle ro sis, ca rd ia c e m bolism is the se co n d c o m m o n ca u se of isch e m ic stro ke (3,4). R e cent stu d ie s have s h o w n th a t 2 3 -3 9 % o f y o u n g a d u lts w ith isch e m ic stro k e s o r tra n s ie n t isc h e m ic a ttacks (TIA) have p o te n tia l ca rd ia c e m b o lic s o u rc e s (5-7). T his situ a tio n e m p h a s is e s the im p o rta n c e of c a rd ia c e v a lu a tio n in u n e x p la in e d is c h e m ic stroke.
T T E is a n o n in v a s iv e te c h n iq u e , p e rm ittin g a s s e s s m e n t of v e n tric u la r and v a lv u la r fu n ction and has long been used to id e n tify th e ca rd ia c
Transthoracic and transesophageal échocardiographie findings in acute ischemic stroke
so u rce of e m b o li (8 -1 2 ). H o w e ve r, w ith this te ch n iq u e it is d iffic u lt to in ve stig a te left atrium and atrial a p p e n d a g e and d e te ct Intracardiac m asses (13-14). C o m p a re d to the tra n sth o ra cic a p proach , T E E has a h ig h e r yield for evaluating em b o lic s o u rc e s such as left atrial th ro m b u s or tu m o rs, atrial septal d e fe c t o r aneurysm with p a te n t fo ra m e n ovale, m itral va lve prolapses, v a lv u la r s tra n d s and a o rtic arch d ise a se with pro tru d in g a th e ro m a s (15-18).
In th is study, w e c o m p a re d T TE and TE E to d e te rm in e the s e n s itiv ity of T E E in d e tecting potentia l ca rd ia c so u rc e s of em boli.
MATERIALS A N D M ETHODS
T his w a s a p ro s p e c tiv e stu d y of c o n se cu tive ly ad m itte d p a tie n ts w ith is c h e m ic stroke. T he study p o p u la tio n co n s is te d of 46 c o n s e c u tiv e patients (26 m en and 20 w o m e n , m ean age 5 9 ± 1 5 years) ad m itte d to the N e u ro lo g y D e p a rtm e n t b ecause of T IA or a cute c o m p le te stro ke in a five m onths period. T he d ia g n o s is of stro ke o r T IA w a s m ade by tw o n e u ro lo g ists. S tro ke w a s de fin e d as an acute focal n e u ro lo g ic d e fic it th a t lasted m ore th a n 24 h o u rs a n d T IA w a s d e fin e d as a n e u ro lo g ic d e fic it th a t re so lve d w ithin 24 hours. All p a tie n ts u n d e rw e n t m e d ica l and n e u rolog ical e xa m in a tio n . C lin ica l d a ta w e re o b ta in e d from each p a tie n t and routine la b o ra to ry in ve stig a tio n s in c lu d in g c h e s t ra d io g ra m , tw e lv e lead e le c tro c a rd io g ra m , g e n e ra l b lo o d c h e m is try (c o m p le te b lo o d c o u n t, e ry th ro c y te se d im e n ta tio n rate, a n tin u c le a r fa ctor, fibrinogen , lipid p rofile, fa sting g lu c o s e level, h e p a tic and renal fu n ctio n s) w e re ca rrie d out. B rain im aging (c ra n ia l c o m p u te d to m o g ra p h y o r m a g n e tic re s o n a n c e im a g in g ) w e re u s e d to e x c lu d e in tra ce re b ra l h a e m o rrh a g e . C a ro tid u ltrasound (B m ode and D oppler) w a s also perform ed.
O f the 46 p a tie n ts; 17 had T IA and 29 co m p le te stroke. T he te rrito ry of the ca ro tid artery w as im p lica te d in 36 (79% ) p a tie n ts and the territory of the b a s ila r a rte ry in 10 (21% ) patients. All of them w e re s u s p e c te d of having re cent em bolic events.
TTE and TE E w e re a p p lie d to all 46 patients each by a d iffe re n t blind in v e s tig a to r w ithin seven
days in the D e p artm ent of C a rd io lo g y at Siyam i Ersek H ospital. T he precordial e chocardio gram w as p erform ed w ith a V ingm ed C FM 750 using 3.2 5 M H z and 3.75M H z probes and TE E using a 5 .0 M H z m o n o p la n e p ro b e in te rfa c e d w ith a T o s h ib a S S H -1 6 0 im a g in g s yste m . C o n tra s t im aging w as p erform ed during both surface and tran se so p h a g e a l ech o ca rd io g ra p h y. Five to ten m illilitres of agitated saline solution w as injected into the left a n tecub ital vein during both norm al respiration and the strain phase of V alsalva M aneuver. Upon arrival of the first m icrobubbles in the right atrium the patient resum ed norm al re sp ira tio n . C o n tra s t s tu d ie s d u rin g V a lsa lva M a n e u v e r w e re re p e a te d if a firs t in je ctio n yielded a negative or q u e stio n a b le result. S tudies w ere judged positive if m icrobubble s appeared in the left atrium w ithin 3 ca rd ia c cycles of their a p p e a ra n ce in the right atrium (19).
T he positive fin d in g s of clinical history, physical e x a m in a tio n , e le c tro c a rd io g ra p h y and c h e s t radiogram of the p a tients w ere used as criteria of ca rd ia c ab n o rm a litie s (T able I). P atients w ere d ivided into tw o g roups; 65% of the patients had clinical sign of heart dise a se and 35% had no evid e n ce of ca rd ia c dise a se (6).
Table I. C ardiac abnorm alities on clinical evaluation
INVESTIGATION FINDINGS
Clinical history Angina pectoris
Heart rhythm disturbances Previous myocardial infarction Physical examination Organic heart murmur
Sings of heart failure Electrocardiography Atrial fibrillation
Old mycardial infarction
Ischemic repolarization abnormality Cardiomegaly
(cardiothoracic ratio > 50%)
T he fo llow ing é c h o ca rd io g ra p h ie fin d in g s w ere c o n s id e re d as p o s s ib le c a rd ia c s o u rc e s of em boli; left atrial or app e n d a g e throm bus, atrial m yxom a, m itral or a ortic valve vegetatio n, atrial septal ane u rysm (ASA), p a tent foram en ovale
w ith in te ra tria l s h u n tin g , le ft v e n tric u la r w all m otion a b n o rm a lity o r left v e n tric u la r aneurysm , s p o n ta n e o u s echo c o n tra s t in the left atrium , a th e ro scle ro tic p la q u e s in the aorta. A o rtic arc p la q u e s w e re c h a ra c te riz e d a c c o rd in g to p reviously d e scrib e d c rite ria as large (> 4 m m in thickness), sm all (< 4 m m in th ickn e ss), with ulceration and / or m obile (20). A S A w a s defined a ccording to crite ria : (1) d ia m e te r o f the base of the a n e u ry s m a tic p o rtio n o f in te r atrial septum (IA S ) m e a s u rin g > 15 m m a nd e ith e r (2) p ro trusion of the IAS, or part of it, > 15 mm beyond the p lane of the IAS or (3) ph a sic excursion of the IAS during the c a rd io re s p ira to ry cycle > 15 m m in total a m p litu d e (21). D ata w ere c o m p a re d in g ro u p s b e tw e e n p a tie n ts w ith clinical heart d ise a se and th o se w ith o u t, using F is h e r's E x a c t T e s t. A 'p ' v a lu e < 0 .0 5 is co n sid e re d significant.
RESULTS
T ra n s e s o p h a g e a l e c h o c a rd io g ra p h y w a s w ell to lerated in all 46 p a tients and did not lead to any com plication.
Clinical Evidence of Heart Disease
Table II s u m m a rize s the clinical c h a ra c te ris tic s of 30 patients w ith ca rd ia c m a n ife sta tio n s. In this group som e p a tients had m ore than one ca rd ia c risk p a ra m e te r. C a rd io m e g a ly , m y o c a rd ia l infarction and atrial fib rilla tio n w e re the m ost com m on fe a tu re s of heart d ise a se . T h e re w e re 5 patients w ith rh e u m a tic h eart d isease, o f w hom o ne had e n d o c a rd itis . F o u r p a tie n ts had prosthetic valve re p la c e m e n t and 1 p a tie n t had sick sinus syndrom e.
Table II. Clinical characteristics of 30 patients with cardiac
manifestations* n % Previous Ml 12 40 Atrial fibrillation 12 40 valvular 3 nonvalvular 9
Rheumatic heart disease 5 16
Prosthetic valve 4 13
Cardiomegaly 17 56
* Some patients had more than Ml: myocardial infarction
one cardiac manifestations
Risk factor Evaluation
T h e p a tie n ts w e re a ls o e v a lu a te d fo r the p re s e n c e of risk fa c to rs fo r c e re b ro v a s c u la r d ise a s e s . A ge, sex, h isto ry of h y p e rte n s io n , d ia b e te s m ellitus, sm o kin g , h yp e rc h o le s te ro le m ia w e re not sig n ific a n tly d iffe re n t in th e tw o g roups. A m ong the p a tie n ts w ith c lin ica l h eart d ise a se o b e s ity rate is h ig h e r th a n th e o th e r g roup (p<0.05) (T able III)
Table III. Presence of risk factors for cerebrovascular
disease
Patients with clinical Patients without clinical
heart disease heart disease
Risk Factor (n=30) (n=16) P Age (years) 60 55 NS Male sex 14 (46% ) 10 (62% ) NS Hypertension 19 (63% ) 7 (44% ) NS Diabetes mellitus 3 (10% ) 3 (18% ) NS Smoking 8 (26% ) 7 (43% ) NS Myocardial infarction 7 (23% ) 0 (0% ) NS Hypercholesterolemia 13 (43% ) 3 (18% ) NS Obesity 8 (26% ) 0 (0% ) p<0.035 ‘ NS=non significant (p>0.05)
Carotid Artery B mode and
Doppler Ultrasound
B m ode u ltra so u n d and D o p p le r stu d ie s of the ca ro tid a rte rie s w e re p e rfo rm e d in 46 p a tie n ts and carotid a rte ry ste n o s is > 5 0 % w a s co n s id e re d to be sig n ifica n t. T a b le IV s u m m a riz e s the results of c a ro tid a rte ry u ltra s o n o g ra p h ic e v a lu a tio n . T h e re w e re on ly 3 p a tie n ts w ith se ve re ca ro tid stenosis.
Cardiac Source of Embolism
Left atrial th ro m b i w e re d e te c te d in 10 p a tie n ts by T E E a lth o u g h n o n e o f th e s e th ro m b i w e re
Table IV. Results of carotid artery Doppler ultrasound
Patients with Patients without cardiac manifestations cardiac manifestations
n:30 n:16
Significant stenosis
>50% 2 1
Nonsignificant stenosis
Transthoracic and transesophageal échocardiographie findings in acute ischemic stroke
im aged by tra n s th o ra c ic app ro a ch (Table V). T h ree of ten p a tie n ts s h o w e d no evidence of ca rd ia c d ise a se . T E E also p ro vid e d su p e rio r v is u a lis a tio n o f m itra l a nd a o rtic v a lv e v e g e ta tio n s. A tria l m y xo m a w as d e te cte d in 1 p a tie n t w ith o u t c a rd ia c s ig n s by T E E . T E E dete cte d p ro tru d in g a th e ro s c le ro tic p laque s in the a o rta in 7 p a tie n ts w ith ca rd ia c signs and 3 w ithout. In 6 p a tie n ts, left atrial sp o n ta n e o u s e c h o c o n tra s t w a s d ia g n o s e d by the pre se n ce of the c h a ra c te ris tic 's m o k e lik e sw irling' by TEE. T ra n s e s o p h a g e a l e c h o c a rd io g ra p h d e te c te d atrial septal a n e u ry s m in o ne you n g adult with u n e xp la in e d stroke. P a te n t fo ra m e n ovale w as im aged in 4 of 46 p a tie n ts and th e y had interatrial sh u n tin g d e m o n s tra te d by c o n tra s t echo by TEE only. Left v e n tric u la r w all m otion a b n o rm a lity w as e q u a lly id e n tifie d by both T T E and TEE.
Table V. Results of transthoracic and transesophageal echocardiography
Patients with cardiac Patients without manifestations cardiac manifestations
n=30 n=16
FINDINGS HE TEE TTE TEE
LEFT ATRIAL OR APPENDAGE THROMBUS 0 7 * 0 3 M ITRAL OR AORTIC VALVE VEGETATION 0 2 0 0 ATRIAL MYXOMA 0 0 0 1 AORTIC ATHEROMA 0 7 “ 0 3 ATRIAL FIBRILLATION +MITRAL STENOSIS 6 7 0 0 ATRIAL SEPTAL ANEURYSM 0 0 0 1 SPONTANEOUS ECHO CONTRAST 0 6 " 0 0 PFO + INTERATRIAL SHUNT 0 3 0 1 LEFT VENTRICULAR W ALL MOTION ABNORMALITY 6 6 0 0 LEFT VENTRICULAR ANEURYSM 1 1 0 0
• P<0.01, **P<0.05 in Fisher's Exact Test
TTE: transthoracic echocardiography TEE: transesophageal echocardiography PFO: patent foremen ovale
W e de te cte d v a lv u la r stra n d s in 12 patients. M itral and aortic valve echo strands are a new e n tity a nd th e s e p ro c e s s e s ha ve been associated with e m b o lic phenom ena.
In the 30 patients w ith clinical evidence of heart d is e a s e T T E d e te c te d a c a rd ia c s o u rc e of em bolus in only 12 patients, w hile in 18 patients th e re s u lts w e re n e g a tiv e . W hen T E E w as applied to these 18 patients, a cardiac source of em boli w as detected in a fu rth e r 13 of them . On the o ther hand in the 12 p a tients w ho had p o s itiv e fin d in g s w ith T T E , th e re w a s no diffe re n ce w hen T E E w as applied. W hen we look at the 16 patients w ith o u t evidence of cardiac disease, TTE did not de te ct any cardiac source of em boli w h e re a s w hen TE E w as applied to the sam e gro u p 7 patients w ere detected to have ca rd ia c source of em boli.
T ra n se so p h a g e a l e ch o ca rd io g ra p h y revealed a potentia l source of ca rd ia c em bolism in 32 (69% ) patients. 7 (21% ) of these show ed no clinical evidence of heart disease.
DISCUSSION
T h is study d e m o n stra te s th a t,tra n se so p h a g e a l e c h o c a rd io g ra p h y is m o re s e n s itiv e than tra n s th o ra c ic a pproach in the detection of the potential source of ca rd ia c e m bolus in stroke patients, either w ith or w ith o u t know n cardiac d is e a s e s . It is c o n c lu d e d th a t T E E a llo w s e x c e lle n t v is u a liz a tio n of c a rd ia c s tru c tu re s , esp e cia lly those fa rth e st aw ay from the chest wall, thus it has s u p e rio r resolution of cardiac s tru c tu re s s u ch as le ft a triu m , le ft a tria l a p p e n d a g e , a tria l s e p tu m an d m itra l va lv e co m p a re d to TTE (13-18, 22).
In o u r study, T TE did not reveal any potential ca rd ia c so urce of e m b o lu s in 16 patients w ithout e v id e n c e of c a rd ia c m a n ife s ta tio n s . T E E dete cte d a po te n tia l ca rd ia c source of em bolus in 83% p a tie n ts w ith clinical heart dise a se w hile TTE dete cte d 40% of them . TE E found a cardiac source in 4 3 % of the p a tients w ith o u t cardiac m a nifestation s. A trial fib rilla tio n is d escribed as a c o n trib u to r fo r ce re b ro v a s c u la r accidents (23). A tria l fib rilla tio n is c lo s e ly a s s o c ia te d w ith rh e u m a tic v a lv u la r h e a rt dise a se and both atrial fib rilla tio n and m itral s te n o sis creates statis of
blood in th e le ft a triu m (2 4 ,2 5 ). T h e s e are p re d is p o s in g fa c to rs fo r s p o n ta n e o u s e chocon tra st. It is su g g e ste d th a t s p o n ta n e o u s e ch o c o n tra s t m ay be a p re c u rs o r fo r th ro m b u s fo rm a tio n . It is fo u n d th a t p a tie n ts in a tria l fib rilla tio n w ith le ft a tria l s p o n ta n e o u s e ch o co n tra st s u ffe r from th ro m b o e m b o lic stroke m ore than p a tie n ts in atrial fib rilla tio n w ith o u t s p o n ta n e o u s e c h o c o n tra s t (26,27). S p o n ta n e o u s e ch o co n tra st w as d e te cte d in 6 patients, all of w hom had ca rd ia c m a n ife sta tio n s and five of w hom had atrial fib rilla tio n . T T E did not identify a tria l m a s s e s , w h ile tra n s e s o p h a g e a l e ch o c a rd io g ra p h y visu a liz e d left atrial th ro m b u s in the left atrial a p p e n d a g e . T h re e of ten patients show ed no e v id e n c e of ca rd ia c dise a se a fte r history taking and c lin ica l e xa m in a tio n . T hese patients are in the 'high risk g ro u p ' fo r ca rd ia c source of e m b o lism a c co rd in g to N IN D S S troke D ata B ank C la ssifica tio n (28,29). T E E de te cte d v a lvu la r v e g e ta tio n in tw o p a tie n ts; one of them had p ro sth e tic va lve and the o th e r had rh e u m a tic valve dise a se w ith e n d o ca rd itis.
P a te n t fo ra m e n o v a le (P F O ) has been associated w ith brain in fa rctio n and it w as show n that it is p resent in 2 0 % to 3 5 % of the popula tion (9,30). TE E is m ore se n s itiv e than T TE for visualizing p a te n t fo ra m e n o va le size and shunt direction, and co n tra s t im a g in g im p ro ve s the d iagno stic va lue of this p ro c e d u re (13). PFO w as detected in fo u r p a tie n ts and in te ra tria l shunting w as show n by co n tra s t study. It w a s fo u n d in one patient w ith o u t ca rd ia c sign clinically.
It has b e e n s u g g e s te d th a t a tria l s e p ta l a n eurysm s o c c u r m ore c o m m o n ly in patients w ith u n e x p la in e d s tro k e . T h e tw o p ro p o s e d p a th o p h ysio lo g ic m e c h a n is m s leading to stroke w ere; p a ra d o x ic e m b o lism and th ro m b u s w ithin the a tria l s e p ta l a n e u ry s m (2 1 ,3 1 ). A S A is fre q u e n tly a s s o c ia te d w ith PFO . W h ile T E E detected A S A in 8% of the p a tie n ts w ith stroke, TTE visu a lize d A S A in on ly 3 % of th e se patients (31). W e d e te cte d A S A in a you n g a d u lt with unexplained stroke. She had no clinical sign and TTE w as norm al.
A ortic disease w ith u lce ra te d p la q u e s both in the a o rtic arch and th o ra c ic aorta w a s d e te cte d by TE E to be a n o th e r so u rce o f e m b o lism (20). R ecent studies show that, the in cre a sin g risk w as o b served e sp e c ia lly fo r le sio n s of > 4m m in the
a s c e n d in g a o rta o r p ro x im a l arch (32). W e v is u a liz e d a o rtic p la q u e s in 7 p a tie n ts w ith ca rd ia c m a n ife s ta tio n s and in 3 p a tie n ts w ith o u t ca rd ia c m a n ife sta tio n s. W e co uld not d e te c t the th ic k n e s s of the p la q u e s and tra n s e s o p h a g e a l d e v ic e w ith m o n o p la n e p ro b e lim ite d th e se n sitivity.
Left v e n tric u la r w all m otion a b n o rm a lity and left v e n tric u la r a n u e ry s m w e re e q u a lly id e n tifyin g in both te ch n iq u e s. All these p a tie n ts had co ro n a ry heart d is e a s e and in s o m e p a tie n ts pre vio u s m yocardial in fa rctio n w a s obse rve d .
V a lv u la r echo stra n d s are new e n titie s w hich h a v e b e e n a s s o c ia te d w ith e m b o lis m (33). S tra n d s are fila m e n to u s and th in a tta c h m e n ts on the ca rd ia c va lve s and th e y m ay s e rve as a nidus fo r th ro m b u s fo rm a tio n . W e d e te c te d v a lv u la r s tra n d s in 12 (2 6 % ) p a tie n ts . It ha s b e e n su g g e ste d th a t stra n d s d e m o n s tra te d w ith T E E ,
Table VI. Results of other clinical trials comparing transthoracic and transesopageal echocardiography for the detection of cardiac sources of embolism
Pop G, et al. (6) (+) Clinical (-) Clinical 32 % by TEE 9 % by TEE 32 % by TTE 2 % by TEE Hofmann T, etal. (11) (+) Clinical (-) Clinical 85 % by TEE 46 % by TEE 76 % by TTE 19% by TTE Pearson AC, et al (13) (+) Clinical (-) Clinical 85 % by TEE 46 % by TEE 76 % by TTE 19 % by HE
DeRook FA, et al. (16)
(+) Clinial (-) Clinical 76 % by TEE 60 % by TEE 19% by HE 30 % by HE Cujec B, et al. (35) (+) Clinical (-) Clinical 79 % by TEE 18% by TEE 38 % by TTE 0 % by TTE
Tuncer N, et al. (present study)
(+) Clinical (-) Clinical
83 % by TEE 43 % by TEE
Transthoracic and transesophageal échocardiographie findings in acute ischemic stroke
are a sso cia te d w ith is c h e m ic stroke, e sp e cia lly in young p a tie n ts (34).
T a b le VI s u m m a riz e s th e re su lts of several clinical tria ls c o m p a rin g T T E and TEE.
O ur re su lts are in a c c o rd a n c e w ith the other stu d ie s and d e m o n s tra te th a t T E E in creases the d ia g n o s tic y ie ld o f d e te c tin g in tra c a rd ia c a b n o rm a litie s and it sh ould be carried out during the early w o rk -u p of th e a cute stroke patients since T E E fin d in g s m ay g u id e the ap p ro p ria te m a n agem e nt.
REFERENCES
1. B o g o u s s l a v s k y J , W e l l e G V , K c g l i T . T h e L a u s a n n e S t r o k e S t u d y ; a n a l y s i s o f 1 0 0 0 c o n s e c u t i v e p a t i e n t s w i t h f i r s t s t r o k e . S t r o k e 1 9 8 8 ; 1 9 : 1 0 8 3 - 1 0 9 2 . 2 . C e r e b r a l E m b o l i s m T a s k F o r c e . C a r d i o g e n i c b r a i n e m b o l i s m . A r c h r i e u r o l 1 9 8 9 : 4 6 : 7 2 7 - 7 4 3 . 3 . M o h r J P , C a p l a n L R , M e l s k i J W , e t a l . T h e H a r v a r d C o o p e r a t i v e S t r o k e R e g i s t r y : A p r o s p e c t i v e r e g i s t r y , n e u r o l o g y 1 9 7 8 : 2 8 : 7 5 4 - 7 6 2 . 4 . B o g o u s s l a v s k y J , C a c h i n C , R e g l i P , e t a l . C a r d i a c s o u r c e s o f e m b o l i s m a n d c e r e b r a l i n f a r c t i o n - c l i n i c a l c o n s e q u e n c e s a n d v a s c u l a r c o n c o m i t a n t s : T h e L a u s a n n e S t r o k e R e g i s t r y , n e u r o l o g y 1 9 9 1 ; 4 1 - . 8 5 5 - 8 5 9 . 5 . B i l l e r J , J o h n s o n M R , A d a m s H P , e t a t . E c h o c a r d i o l o g i c e v a l u a t i o n o f y o u n g a d u l t s w i t h n o n h e m o r r h a g i c c e r e b r a l i n f a r c t i o n . S t r o k e 1 9 8 6 ; I 7 : 6 0 8 - 6 1 2 . 6 . P o p G , S u t h e r l a n d G R , K o u d s t a a l P J , e t a l . T r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n t h e d e t e c t i o n o f i n t r a c a r d i a c e m b o l i c s o u r c e s i n p a t i e n t s w i t h t r a n s i e n t i s c h e m i c a t t a c k s . S t r o k e 1 9 9 0 ; 2 1 : 5 6 0 - 5 6 5 . 7 . R a u h G , P i s c h e r e d e r M , S p e n g e l P A . T r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n p a t i e n t s w i t h f o c a l c e r e b r a l i s c h e m i a o f u n k n o w n c a u s e . S t r o k e 1 9 9 6 ; 2 7 : 6 9 1 - 6 9 4 . 8 . T e g e l e r C H , D o w n e s T R . C a r d i a c i m a g i n g i n s t r o k e . S t r o k e 1 9 9 1 ; 2 6 : 1 3 - 1 8 . 9 . H a r t R G . C a r d i o g e n i c b r a i n e m b o l i s m t o t h e b r a i n . L a n c e t 1 9 9 2 ; 3 3 9 : 5 8 9 - 5 9 4 . 1 0 . L e u n g D Y , B l a c k 1 W , C r a n n e y G B , e t a l. S e l e c t i o n o f p a t i e n t s f o r t r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y a f t e r s t r o k e a n d s y s t e m i c e m b o l i c e v e n t s . R o l e o f t r a n s t h o r a c i c e c h o c a r d i o g r a p h y . S t r o k e 1 9 9 5 : 2 6 : 1 8 2 0 - 1 8 2 4 . 1 1 . H o f m a n n T , K a s p e r W , M e i n e t r z T , e t a l . E c h o c a r d i o g r a p h i e e v a l u a t i o n o f p a t i e n t s w i t h c l i n i c a l l y s u s p e c t e d a r t e r i a l e m b o l i . L a n c e t 1 9 9 0 : 3 3 6 : 1 4 2 1 - 1 4 2 4 . 1 2 . A s i n g e r R W , H e r z o g C A , D i c k C D . E c h o c a r d i o g r a p h y i n t h e e v a l u a t i o n o f c a r d i a c s o u r c e s o f e m b o l i . E c h o c a r d i o g r a p h y 1 9 9 3 , 1 0 : 3 7 3 - 3 9 6 . 1 3 . P e a r s o n A C . T r a n s t h o r a c i c e c h o c a r d i o g r a p h y v e r s u s t r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n d e t e c t i n g c a r d i a c s o u r c e s o f e m b o l i s m . E c h o c a r d i o g r a p h y 1 9 9 3 ; 1 0 : 3 9 7 - 4 0 2 . 1 4 . S h y u K , C h e n J , H u a n g Z , e t a l . R o l e o f t r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n t h e d i a g n o s t i c a s s e s s m e n t o f c a r d i a c s o u r c e s o f e m b o l i s m i n p a t i e n t s w i t h a c u t e i s c h e m i c s t r o k e . C a r d i o l o g y 1 9 9 4 : 8 5 : 5 3 - 6 0 . 1 5 . L a b o v i t z A . T h e i n c r e a s i n g r o l e o f t r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n u n e x p l a i n e d c e r e b r a l i s c h e m i a . E c h o c a r d i o g r a p h y 1 9 9 3 ; 1 0 : 3 6 3 - 3 6 5 . 1 6 . D e R o o k P A , C o m e s s K A , A l b e r s G W , e t a l . T r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n t h e e v a l u a t i o n o f s t r o k e . A n n I n t M e d 1 9 9 2 ; 1 1 7 : 9 2 2 - 9 3 2 . 1 7 . A u t o r e C , C a r t o n i D , P i c c i n i n n o M . M u l t i p l a n e t r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y a n d s t r o k e . A M J C a r d i o l 1 9 9 8 ; 8 1 ( 1 2 A ) : 7 9 G - 8 1 G . 1 8 . A l b e r s G W , C o m e s s K A , D e R o o k P A , e t a l. T r a n s e s o p h a g e a l é c h o c a r d i o g r a p h i e f i n d i n g s i n s t r o k e s u b t y p e s . S t r o k e 1 9 9 4 ; 2 5 : 2 3 - 2 8 . 1 9 . S i o s t r z o n e k P , Z a n g e n e h M , G ô s s i n g e r H , e t a l . C o m p a r i s o n o f t r a n s e s o p h a g e a l a n d t r a n s t h o r a c i c c o n t r a s t e c h o c a r d i o g r a p h y f o r d e t e c t i o n o f a p a t e n t f o r a m e n o v a l e . A m J C a r d i o l 1 9 9 1 ; 6 8 : 1 2 4 7 - 1 2 4 9 . 2 0 . A m e r e n c o P , D u y c k a e r t s C , T z o u r l o C , e t a l. T h e p r e v a l e n c e o f u l c e r a t e d p l a q u e s i n t h e a o r t i c a r c h i n p a t i e n t s w i t h s t r o k e . T i E n g l J M e d 1 9 9 2 ; 3 2 6 : 2 2 1 - 2 2 5 . 2 1 . A g m o n Y, K h a n d h e r i a B K , M e i s s n e r I, e t a l . F r e q u e n c y o f a t r i a l s e p t a l a n e u r y s m s i n p a t i e n t s w i t h c e r e b r a l i s c h e m i c e v e n t s . C i r c u l a t i o n 1 9 9 9 : 9 9 : 1 9 4 2 - 1 9 4 4 . 2 2 . S e w a r d J , K h a n d h e r i a B K , O h J K , e t a l . T r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y : t e c h n i q u e , a n a t o m i c c o r r e l a t i o n s , i m p l e m e n t a t i o n a n d c l i n i c a l a p p l i c a t i o n . M a y o C l i n P r o c 1 9 8 8 ; 6 3 : 6 4 9 - 6 8 0 . 2 3 . C a b i n H S , C l u b b K S , H a l l C , e t a l . R i s k f o r s y s t e m i c e m b o l i z a t i o n o f a t r i a l f i b r i l l a t i o nw i t h o u t m i t r a l s t e n o s i s . A m J C a r d i o l 1 9 9 0 ; 6 5 : 1 1 1 2 - 1 1 1 6 . 2 4 . B r i l e y D P , G i r a u d G D , B e a m e r H B , e t a i. S p o n t a n e o u s e c h o c o n t r a s t a n d h e m o r h e o l o g i c a b n o r m a l i t i e s i n c e r e b r o v a s c u l a r d i s e a s e . S t r o k e 1 9 9 4 ; 2 5 : 1 5 6 4 - 1 5 6 9 . 2 5 . B l a c k I W , H o p k i n s A P , L e e L C , e t a l . L e f t a t r i a l s p o n t a n e o u s e c h o c o n t r a s t : a c l i n i c a l a n d é c h o c a r d i o g r a p h i e a n a l y s i s . J A m C o l l C a r d i o l 1 9 9 1 ; 1 8 : 3 9 8 - 4 0 4 . 2 6 . C h i m o w i t z M l , D e G e o r g i a M A , P o o l e R M , e t a l . L e f t a t r i a I s p o n t a n e o u s e c h o c o n t r a s t i s h i g h l y a s s o c i a t e d w i t h p r e v i o u s s t r o k e i n p a t i e n t s w i t h a t r i a l f i b r i l l a t i o n o r m i t r a l s t e n o s i s . S t r o k e 1 9 9 3 ; 2 4 : 1 0 1 5 - 1 0 1 9 . 2 7 . L e u n g D Y , B l a c k I W , C r a n n e y G B , e t a l. P r o g n o s t i c i m p l i c a t i o n s o f l e f t a t r i a l s p o n t a n e o u s e c h o c o n t r a s t i n n o n v a l v u l a r a t r i a l f i b r i l l a t i o n . J A m C o l l C a r d i o l 1 9 9 4 ; 2 4 : 7 5 5 - 7 6 2 . 2 8 . P o u l k e s M A , W o l f P A , P r i c e T R , e t a l . T h e s t r o k e d a t a b a n k : D e s i g n , m e t h o d s a n d b a s e l a n d c h a r a c t e r i s t i c s . S t r o k e 1 9 8 8 ; 1 9 : 5 4 7 - 5 5 4 . 2 9 . G o m e z C R , T u l y a p r o n c h o t e R . n e u r o l o g i s t s ' p e r s p e c t i v e i n t h e e v a l u a t i o n o f i s c h e m i c s t r o k e . E c h o c a r d i o g r a p h y 1 9 9 3 ; 1 0 : 3 6 7 - 3 7 2 . 3 0 . L y n c h J J . P r e v a l e n c e o f r i g h t t o l e f t a t r i a l s h u n t i n g i n a h e a l t h y p o p u l a t i o n : D e t e c t i o n b y V a l s a l v a m a n e u v e r c o n t r a s t e c h o c a r d i o g r a p h y . A m J C a r d i o l 1 9 8 4 ; 5 3 : 1 4 7 8 - 1 4 8 0 . 3 1 . P e a r s o n A C , H a g e l h o u t D , C a s t e l l o R , e t a t . A t r i a l s e p t a l a n e u r y s m a n d s t r o k e : a t r a n s e s o p h a g e a l é c h o c a r d i o g r a p h i e s t u d y . J A m C o l l C a r d i o l 1 9 9 1 , 1 8 : 1 2 2 3 - 1 2 2 9 . 3 2 . A m e r e n c o P , C o h e n A , T z o u r i o C , e t a l . A t h e r o s c l e r o t i c d i s e a s e o f t h e a o r t i c a r c h a n d t h e r i s k o f i s c h e m i c s t r o k e . H E n g l J M e d 1 9 9 4 ; 3 3 1 : 1 4 7 4 - 1 4 7 9 . 3 3 . C o h e n A , T z o u r i o C , C h a u v e I C , e t a l . M i t r a l v a l v e s t r a n d s a n d t h e r i s k o f i s c h e m i c s t r o k e i n e l d e r l y p a t i e n t s . S t r o k e 1 9 9 7 ; 2 8 : 1 5 7 4 - 1 5 7 8 . 3 4 . R o b e r t s J R , O m a r a l i I , T u l l i o M R , e t a l . V a l v u l a r s t r a n d s a n d c e r e b r a l i s c h e m i a . S t r o k e 1 9 9 7 ; 2 8 : 2 1 8 5 - 2 1 8 8 . 3 5 . C u j e c B , P l a s e k P , V o l l C e t a l . T r a n s e s o p h a g e a l e c h o c a r d i o g r a p h y i n t h e d e t e c t i o n o f p o t e n t i a l c a r d i a c s o u r c e o f e m b o l i s m i n s t r o k e p a t i e n t s . S t r o k e 1 9 9 1 ; 2 2 : 7 2 7 - 7 3 3 .
