312
Internal Mammary Artery Anomalies e. P Bauer, M. C. BiIlO · , L. K. VOIl Segesser, A. Laske, and M. I. Turina
Su mmary
An omalien de r Arte ri a mammaria In te r na
The intern al mam ma ry a rte ries (IMA) are considered to be the su perio r co nd uit in coro nary bypass grafting (CABCi ). Anoma lies of a n IMA ca n influence the s urg ical tec hn ique a nd res ults ; th eir true incidence is not we ll known. The IMA's we re visua lise d angiographica lly in 262 consecutive pat ien ts un de rgoing cardiac catheterisatio n p rior to CABG. Sat isfactory vis ua lisation was possible of 4 59/ 524 IMA's st udied (8 8 'Yo). A total of 118/ 4 59 (26 %)s urg ica lly sign ificant ano malies was observe d in 7Y1262 pat ients (30 %); co mmon or igin of a nothe r la rge a rtery in 48/4 59 (11 %), la rge side bra nches in 4 1/459 (9 %), tortuosity in 21/459 (5 %), atyp ica l cou rse or orig in in 5/459 (1 %), at he ros clerotic lesio ns in 2/ 459 (0.4 %) and spas ticity of an IMA in 1/ 459 (0.2 %). Angiographic vis ua lisa tio n of the IMA's res ulted in mod ification of surgical st ra tegy in 11/262 pat ien ts (4 %); met iculous pr ep a ra tion becau se of difficult or atypical IMA a nato my was necessary in 68 /26 2 pa tients (26 %). These result s dem onstrate th at s ign ifica nt a noma lies of the IMA wh ich mig ht- w he n unrecogn ized -jeopa rd ize IMA·flow a fterCABG a re relatively commo n; they might escape detection during IMA ta ke-down but ca n be diagnosed by a ngiograp hy d uri ng cat heterisation .
Die Ar te ria mam ma ria int erna (lMA) gilt zur Zeit als bcstes BypassgefaB fl lr d ie kor ona re Hevas kula risation. Ano ma lie n der IMA konne n die eh ir u rgise he Teeh nik un d d ie Hesult ate bee influsse n: allerdings ist d ie Ha uflgkeit solc her Anom alle n n ieh t genau bekannt. Die IMAe w u rden bei 262 konsekutiven Patie nten , d ie sich einer aortokorona re n Bypa ssoper ation unterz iehen m uBten, a ngiographisc h dar gostellt. Insgesa mt kon nt en 45 9/52 4 (88 %) Arterien beurteilt worden. Insgesa mt w ur de n 11 8/4 59 (26 °/.,) chirurgisch sign ifikan te Ano ma lie n b el 79 / 262 (30 %) Pat ien te n beo bachtet: Geme insa me r Abgang ciner an deren groBen Arterie in 48 / 459 (26 %) Fallen , groBer Seite nast in 4 1/459 (9% ), geschlangelter Verlauf in 21/459 (5 %), aty p ische r Verlauf oder Abgang der IMA in 5/ 459 (l %), arteriosklerc tische Veranderung in 2/ 459 (0.4 %) Fallen und spastische IMA in 1/ 459 (0.2%) Fa ll. Die angiographisc he Da rstellung de r IMA hatte bei 11/262 (4 %) Pat icn te n cine Ande ru ng d ur ch ir urg isc hen Takti k zur Fclge: beson ders vorsicht ige Pra pa ration wegen atypischer IMA-An atomie wa r bel 68 /262 (26 %) Pat ien ten notw end ig . Die Un ters uch un gen zeigen . daf sig nifikante IMA-Anomalien rela tiv h a u rlg sind . d ie wa h rend d er tiblichen Prapara tion u nentdeckt bleiben. Solche Anomalien kon non angiograp h isch wa h re nd de r Il erzkatheth eru ntcrs uc hung da rgestellt we rden und ermoglichen da nn e ine Andcrung des chi rurgischen Vorgehens .
Key words
Intern al ma mmary artery - Anomalies - Su rgery
Introduction
Results
The intern al mamm ary arter y (IMA) is considered the con-
A total of 262 patients undergoing CABG were studied. Mea n age at the time of operation was 57.9 years (range 36-75 years) . A total of 5241MA's were studied ; sa tisfactory visualisation was possible in 459/ 524 (88%). Only patients with at least one opacified arter y were ente red in the protocol. Angiogra phy was perform ed in all patients without complication. We found a total of 118 significant a nomalies in 79/ 26 2 pati ents (30 %). The freq uency of anomalies is show n in Table 1, illustr ation of the anomalies in Figs. 1-5 . In a ddition to these ano malies 37 sclerotic lesions of the subclavian a rter y we re visible. In 5 cases there was a significa nt (> 50% ) stenos is. These pati ents wer e excluded from the study. In 11/ 262 patients (4%) surgical strategy was cha nged after critical examination of the preoperative angiogra m (Table 2). In 3 cases the IMA was not used because of its common origin with the thyreocer vical a nd costocervical trunk. The spastic and 2 sclerotic a rteries were also not used for corona ry bypass. An an omalous course of an IMA was another factor wh ich led to abandoning the artery. The surgical technique was modified in 4
duit of choice for corona ry revascular isation . However, ana tomical fa ctors and nota bly anomalies of IMA's are known to intluence the surgical results; thei r tru e incidence is not well known (1 7, 21- 23). The present study was undertaken to exam ine frequency and types of IMA an omalies with possible influence on surgical strategy and resu lts, Methods Th e IMA's were a ngiographically visu alis ed a fter routi ne le ft-heart catheterisa tion . The tip of the cathe ter wa s place d nea r or into the IMA orifice. Arteriograms were recorded in th e postero-anterior project ion. IMA a ngiograms we re take n by ha nd injection of 10 -15 ml of d ilute d contra st med iu m . Th e arteriograms we re view ed prior to CABe; a nd analyzed acco rding to a sta ndard p ro tocol. Atte ntion was give n to la rge b ra nches w ith commo n 1 ~I A origi n, to side branches w ith a diameter of mere tha n 30 % of IMA dia meter, to ve ry to rt uous a rte ries (more th a n 3 angles less tha n 900), IMA's w ith aty pical o rigin or course , small and s pas tic IMA's a nd IMA's wit h sclerotic lesions.
Thora e. cardiovasc. Surgeo n 38 (1990) 312 -315 © Georg Thieme Verlag Stuttga rt New Yor k
Received for Publication: Apr il 2, 1990
Downloaded by: National University of Singapore. Copyrighted material.
Clinic for Card iovascu lar Surge ry .. Departme nt of'Hadiology Un ivers ity Hospital. Zu rich, Sw itzerland
Thom e. eardiollQSe. Su rgeon 38 (1990)
Internal Alam mary A rtery Anomalies
Fig.3 Tortuonsinterna lmammaryartery
Table 1 Frequencyof IMAanomalies patients (n = 262) Common origin Largesidebranches Tortuosity Lateral origin Sclerotic lesion Atypical course Spasticity
32 (12.2%) (8.8 %) 23 16 (6.1 %) 4 (1.5%) 2 (0.8%) 1 (0.4%) 1 (0.4%)
Total
79 (30.2 %1
313
(IMA)
IMA
Downloaded by: National University of Singapore. Copyrighted material.
r
Fig. 1 Common origin of aninternal mammary artery (IMA) CCT: costeocervical trunk; TCl thyreocervical trunk; CAT: catheter
Fig.4 Lateral origin of internal mammaryartery (IMA) SCA subclavian artery; TCT: thyreocervical trunk
Table 2
Consequences of IMA anoma lieson surgicalstrategy patients (n = 262)
IMAnot used (Commonorigin,sclerotic lesion,spasticity, atypicalcourse) IMAused, technique modified (lateral origin)
Fig. 2 Large side branch CAl catheter
7
(27%)
4
(1.5%)
IMAused,meticulous preparation (Large side branch, tortuosity)
68 (26%)
Total
79 (30.2%)
E. P. Baue r. M. C. Bino. L. K. v an Seg esser. A. Laske. M. I. Turina
Thome. eard iovase. Surgeon 38 (1990)
IMA
Fig. 5 Atypical course of an internal mammary artery(lMA) seA: subclavian artery; TCT: thyreocervical trunk
cases with laterallMAorigin. In these cases all tissue adja cent to the IMA was divided. In 68/262 patients (26 %) meticulous surgical technique was necessary based on a difficult or atypical lMA anatomy.
reason for rejection. In this special case complete mobilisation was not possihle. Modiflcation of surgical technique was perform ed in patients with lateral lMA origin. In these patients an IMA can be injured very easily at the level of the first rib . Futhermore it is necessary to free all tissue su rrounding the IMA to preven t tra ction and angulation. which may influence now (9. 19). Very meticulous prep ra tion of an IMA is necessary in cases with atypical or difficult anatomy (26 % in the present series). Large side br an ches. especially proximal bran ches near the IMA origin, are difficult to divide because of poor exposure. If not divided they may cause angulation and reduction ofl MA now.As report ed by others steal phenom enon due to enlarged side br anches may occur . with resulting recurrence of ang ina despite revasculari sation (17, 21. 22). Dissect ion of very tortu ous IMA's is difficult: these arte ries are more eas ily inju red during take-down . This stu dy has shown that preo perative angiog ra phy of IMA's may be performed during routine coro narography. without risk an d with minima l time -loss. to visua lise anomalies and that these are relatively common. may deteriorate IMAflow. and can influence su rgical st rategy . If the surgeon knows beforehan d what lMAanomalies he can expect he is given the opportunity to plan a safer surgical strategy. Referen ces 1
Discussio n
The IMA has heen shown to be the conduit with the grea test longevity among those curren tly available for CABG (7. 9. 16.25). To increase the number of acceptable grafts more emphasis shou ld be given on obta ining an IMA in good condition. Various factors a re known to influence IMA now. One can distinguish a natomical factors (anomali es. small caliber. sclerotic lesions) (7.16.21 -23) functional factors (proximal subclavian sten osis. drugs. spastic tend ency) (1. 2.4, 5. 8. 11. 12. 13, 15. 16. 19. 20. 26. 27) and technical factors (6.16.19). Meticulous surgica l tech nique and knowledge of IMA anatomy a re important factors in improving the number of availab le arte ries . Evalua tion of IMA anatomy is possihle hy preoperative angiography. Therefore sev eral authors recommend preoperative aortic arch ang iograp hy prior to CABG (5, 18. 23). Vein instead of an IMA was used in cases with a cornmon origin of thyreocervical trunk (TCT) and costocerv ical trunk (CCT) with IMA: in these cases occurrence of stea l phenom enon between coronary arte ries an d TCT is possible. especially in cas es with reduced coronary run -off, To divide TCT a supraclavicular.approach would be necessary as described in a case report from our clinic (24). Arteriosclerosis and spas ticity of an IMA were other reasons for not usin g it. Sclerotic lesions of IMA's are ra re: they are mostly depend ent on patients' age (10.14.23). Spastic IMA'swhich might have a detremental elTect on now are rarely found in angiograms. An accurate grading of spasticity is difficult preoperatively. and angiog raphic observation of an IMA spasm has rarely been documented (11). The refore. intraoperative measu rements of gra ft flow is recommended by some authors (4. 6). Atypical course of an IMA in combination with common origin of TCT and CCT was anothe r
2
3
~ 5
6
7
8
9
10
II
12
13
14
Basnour, T. T.. J. Crew. S. S. Kabbani, D. Ellertson. E. S. l/an na. and T. O. Cheng: Symptomatic coronaryandcerebral steal after internal mammary-coronarybypass. Am. HeartJ. 108 (1984 ) 177-1 78 Blache. c.. and A. Chaux: Spasm in mammary artery grafts . Ann. Thorae. Surg. 45 (1988) 586 Brown . A. H.: Coronary steal by internal mammary gran with subda vian stenosis. J. Thorac. Cardiovasc. Surg. 73 (1977) 690-693 Gree n. G. E.: Rate blood now from the internal mammary artery. Surgery 70 (1971 ) 809-8 13 Harj ola. P. T.. and M. Valle: The importance of aort ic arch or subclavian angiography before coronary reconstruction. Chest 66 (1974)436- 438 Huddlest on. C. B.. W. S. Sto ney. C. S. Thomas. et 01.: Internal mammaryarterygrafts : Technical factors influencingpatency.Ann. Thorae . Surg. 42 (1986 ) 543-549 toert, T.. K. Huttun en. Ch. Landau. and V. O. Bjerk: Angiographic studies of internal mammary artery grafts 11 years after coronary bypass grafting. J. Thorac. Cardiovasc. Surg. 96 (1988) 1-1 2 Jeu . G. K. . J. M. Ar cidi . L. M. Dors ey . et al .: Vasoactive drugeffects on blood now in internal mammary and saphenous vein grafts . J. Thcrac. Cardiovasc. Surg. 94 (1987) 2 Jones. E. L.. J. F. Lutz. S. B. King . S. Powelson. and W. Knopf: Extended use of internal mammary artery gran: important anatomic and physiologic considerations. Circulation 74 (1986) Suppl. III 42- 47 Kay . II. R.. M. E. Korns. R. J. Flemma. A . J. Tector, and D. Lep ley : Atherosclerosis ofthe internal mammaryartery.Ann.Thorac. Surg. 21 (1976) 504- 507 Kong. B.. H. Kopelman . B. L. Segal. and A. S. Iekandrian: Angi egraphic demonstration of spasm in a left internal mammaryartery used as a bypass to the left anterior descending coronary artery. Am. J. Cardiel. 61 (1988) 1363 Lef m k, E. A. : The internal mammary artery bypass gran: praise versus practice. Tex. Heart Inst. J. 14 (1987) 139-1 43 Marsh all. W G.. E. C. Mill er. and N. T. Kouchoukos : The coronary subclavian steal syndrome: report of a case and recommendations for prevention and management. Ann. Thorac. Surg. 46 (988) 93-96 Ne mes . A.. P. Sotonyi. A. Balogh. und S. J. Nagy : Verwendung der Arteria mammaria interna zur myokardialen Revaskularisalion. Acta Chir. Scient. Hung 18 (1977) 123-1 28
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3 14
Internal Mommorq Arter.lJ Anomalies
3 15
za S ingh. R. N.: Internal mamm a ry ar teriogra phy. Cathet. Car dlovasc. Diagn. 6 (1980) 439 -449 Z.f Tor tinl, H.. W S teinbrunn. L. Kappenberqe r. N. Goebel. and /1.1. Turina: Anomalous origin of the thyreocervical tru nk as a cause of residual pain after myocard ial revascu laris ation with internal mammary artery. Ann . Thora c. Surg. 40 (1985) 302-304 as Tector , A. J.: Fifteen year's experience with the intern al mam mary art ery graft. Ann . Tho rac. Surg . 42 (1986) Suppl. II 22-27 ae Ty ras. D. II.. and II. B. Barn er: Corona ry subclavian steal. Arch. Surg. 112 (1977) 1125 -1127 Z7 Valentine. H. J.• H. E. Fry. K. R. IVheelan. D. F. Fish er. and (; . P. Clagell: Coronary-subclavian steal from reversed now in an inter nal mammary artery used for coronary bypass. Am. J. Cardiol. 60 (1987) 719 -720
Erwin P. Bauer MD
Clinic for Cardiovascular Surgery University Ilosp ita l Hamlstralle 100 Ch-809 1 Zurich/Switzerland Downloaded by: National University of Singapore. Copyrighted material.
Nimiem . M. L . J. I. /I af t. 1. E. Golds tein . and H. W lIobs on: Retrogra de internal mamm ary artery flow and resistan t ang ina pectoris. Cathet. Cardiovasc. Diagn. 12 (1986) 93 -95 If> Olea rchyk. A. S.• and G. J. Magovern : Internal mammary a rtery grafting. J. Thorac. Cardiovasc . Surg. 92 (1986) 1082 - 1087 17 Pelias. A. J.: A case of postoper ative intern al mamm ary stea l. J . Thorac. Cardiovasc. Surg. 90 (1985) 794-796 18 Hainer. W G.. T. H. S adler. and M. S. Liggell : Internal mamm ary arteriograp hy prior to coronary bypass surgery . Chest 64 (1973) 523-524 19 Reul. G. J.: Presen t status of the internal mammary arte ry as a coronary art ery bypass conduit at the Texas Heart Instit ute. Tex. Heartlnst. J. 12 (1985) 211-219 20 S arabu . M . H.• J. A. McClung. A. Fass . and G. E. Heed : Early postoperative spas m in left intern al mammary a rte ry bypass grafts . Ann . Thora c. Surg. 44 (1987 ) 199 ar Singh. H. N.. and G. J. Magol'ern : Internal mammary graft: impr oved flow resulting from correction of steal phenom enon . J. Thorac. Cardiovas c. Surg. 84 (1982) 146 -1 49 aa S ingh. H. N.. and J. A. S osa: Intern al mammary artery -coronary artery anastomosis. J . Thorac. Cardiovasc. Surg. 82 (1981) 909 -914 IS
Th om e. ea rdiovase. ~~' u rg e(J 1l 38 (1990)
Internal Mammary Artery Anomalies e. P Bauer, M. C. BiIlO · , L. K. VOIl Segesser, A. Laske, and M. I. Turina
Su mmary
An omalien de r Arte ri a mammaria In te r na
The intern al mam ma ry a rte ries (IMA) are considered to be the su perio r co nd uit in coro nary bypass grafting (CABCi ). Anoma lies of a n IMA ca n influence the s urg ical tec hn ique a nd res ults ; th eir true incidence is not we ll known. The IMA's we re visua lise d angiographica lly in 262 consecutive pat ien ts un de rgoing cardiac catheterisatio n p rior to CABG. Sat isfactory vis ua lisation was possible of 4 59/ 524 IMA's st udied (8 8 'Yo). A total of 118/ 4 59 (26 %)s urg ica lly sign ificant ano malies was observe d in 7Y1262 pat ients (30 %); co mmon or igin of a nothe r la rge a rtery in 48/4 59 (11 %), la rge side bra nches in 4 1/459 (9 %), tortuosity in 21/459 (5 %), atyp ica l cou rse or orig in in 5/459 (1 %), at he ros clerotic lesio ns in 2/ 459 (0.4 %) and spas ticity of an IMA in 1/ 459 (0.2 %). Angiographic vis ua lisa tio n of the IMA's res ulted in mod ification of surgical st ra tegy in 11/262 pat ien ts (4 %); met iculous pr ep a ra tion becau se of difficult or atypical IMA a nato my was necessary in 68 /26 2 pa tients (26 %). These result s dem onstrate th at s ign ifica nt a noma lies of the IMA wh ich mig ht- w he n unrecogn ized -jeopa rd ize IMA·flow a fterCABG a re relatively commo n; they might escape detection during IMA ta ke-down but ca n be diagnosed by a ngiograp hy d uri ng cat heterisation .
Die Ar te ria mam ma ria int erna (lMA) gilt zur Zeit als bcstes BypassgefaB fl lr d ie kor ona re Hevas kula risation. Ano ma lie n der IMA konne n die eh ir u rgise he Teeh nik un d d ie Hesult ate bee influsse n: allerdings ist d ie Ha uflgkeit solc her Anom alle n n ieh t genau bekannt. Die IMAe w u rden bei 262 konsekutiven Patie nten , d ie sich einer aortokorona re n Bypa ssoper ation unterz iehen m uBten, a ngiographisc h dar gostellt. Insgesa mt kon nt en 45 9/52 4 (88 %) Arterien beurteilt worden. Insgesa mt w ur de n 11 8/4 59 (26 °/.,) chirurgisch sign ifikan te Ano ma lie n b el 79 / 262 (30 %) Pat ien te n beo bachtet: Geme insa me r Abgang ciner an deren groBen Arterie in 48 / 459 (26 %) Fallen , groBer Seite nast in 4 1/459 (9% ), geschlangelter Verlauf in 21/459 (5 %), aty p ische r Verlauf oder Abgang der IMA in 5/ 459 (l %), arteriosklerc tische Veranderung in 2/ 459 (0.4 %) Fallen und spastische IMA in 1/ 459 (0.2%) Fa ll. Die angiographisc he Da rstellung de r IMA hatte bei 11/262 (4 %) Pat icn te n cine Ande ru ng d ur ch ir urg isc hen Takti k zur Fclge: beson ders vorsicht ige Pra pa ration wegen atypischer IMA-An atomie wa r bel 68 /262 (26 %) Pat ien ten notw end ig . Die Un ters uch un gen zeigen . daf sig nifikante IMA-Anomalien rela tiv h a u rlg sind . d ie wa h rend d er tiblichen Prapara tion u nentdeckt bleiben. Solche Anomalien kon non angiograp h isch wa h re nd de r Il erzkatheth eru ntcrs uc hung da rgestellt we rden und ermoglichen da nn e ine Andcrung des chi rurgischen Vorgehens .
Key words
Intern al ma mmary artery - Anomalies - Su rgery
Introduction
Results
The intern al mamm ary arter y (IMA) is considered the con-
A total of 262 patients undergoing CABG were studied. Mea n age at the time of operation was 57.9 years (range 36-75 years) . A total of 5241MA's were studied ; sa tisfactory visualisation was possible in 459/ 524 (88%). Only patients with at least one opacified arter y were ente red in the protocol. Angiogra phy was perform ed in all patients without complication. We found a total of 118 significant a nomalies in 79/ 26 2 pati ents (30 %). The freq uency of anomalies is show n in Table 1, illustr ation of the anomalies in Figs. 1-5 . In a ddition to these ano malies 37 sclerotic lesions of the subclavian a rter y we re visible. In 5 cases there was a significa nt (> 50% ) stenos is. These pati ents wer e excluded from the study. In 11/ 262 patients (4%) surgical strategy was cha nged after critical examination of the preoperative angiogra m (Table 2). In 3 cases the IMA was not used because of its common origin with the thyreocer vical a nd costocervical trunk. The spastic and 2 sclerotic a rteries were also not used for corona ry bypass. An an omalous course of an IMA was another factor wh ich led to abandoning the artery. The surgical technique was modified in 4
duit of choice for corona ry revascular isation . However, ana tomical fa ctors and nota bly anomalies of IMA's are known to intluence the surgical results; thei r tru e incidence is not well known (1 7, 21- 23). The present study was undertaken to exam ine frequency and types of IMA an omalies with possible influence on surgical strategy and resu lts, Methods Th e IMA's were a ngiographically visu alis ed a fter routi ne le ft-heart catheterisa tion . The tip of the cathe ter wa s place d nea r or into the IMA orifice. Arteriograms were recorded in th e postero-anterior project ion. IMA a ngiograms we re take n by ha nd injection of 10 -15 ml of d ilute d contra st med iu m . Th e arteriograms we re view ed prior to CABe; a nd analyzed acco rding to a sta ndard p ro tocol. Atte ntion was give n to la rge b ra nches w ith commo n 1 ~I A origi n, to side branches w ith a diameter of mere tha n 30 % of IMA dia meter, to ve ry to rt uous a rte ries (more th a n 3 angles less tha n 900), IMA's w ith aty pical o rigin or course , small and s pas tic IMA's a nd IMA's wit h sclerotic lesions.
Thora e. cardiovasc. Surgeo n 38 (1990) 312 -315 © Georg Thieme Verlag Stuttga rt New Yor k
Received for Publication: Apr il 2, 1990
Downloaded by: National University of Singapore. Copyrighted material.
Clinic for Card iovascu lar Surge ry .. Departme nt of'Hadiology Un ivers ity Hospital. Zu rich, Sw itzerland
Thom e. eardiollQSe. Su rgeon 38 (1990)
Internal Alam mary A rtery Anomalies
Fig.3 Tortuonsinterna lmammaryartery
Table 1 Frequencyof IMAanomalies patients (n = 262) Common origin Largesidebranches Tortuosity Lateral origin Sclerotic lesion Atypical course Spasticity
32 (12.2%) (8.8 %) 23 16 (6.1 %) 4 (1.5%) 2 (0.8%) 1 (0.4%) 1 (0.4%)
Total
79 (30.2 %1
313
(IMA)
IMA
Downloaded by: National University of Singapore. Copyrighted material.
r
Fig. 1 Common origin of aninternal mammary artery (IMA) CCT: costeocervical trunk; TCl thyreocervical trunk; CAT: catheter
Fig.4 Lateral origin of internal mammaryartery (IMA) SCA subclavian artery; TCT: thyreocervical trunk
Table 2
Consequences of IMA anoma lieson surgicalstrategy patients (n = 262)
IMAnot used (Commonorigin,sclerotic lesion,spasticity, atypicalcourse) IMAused, technique modified (lateral origin)
Fig. 2 Large side branch CAl catheter
7
(27%)
4
(1.5%)
IMAused,meticulous preparation (Large side branch, tortuosity)
68 (26%)
Total
79 (30.2%)
E. P. Baue r. M. C. Bino. L. K. v an Seg esser. A. Laske. M. I. Turina
Thome. eard iovase. Surgeon 38 (1990)
IMA
Fig. 5 Atypical course of an internal mammary artery(lMA) seA: subclavian artery; TCT: thyreocervical trunk
cases with laterallMAorigin. In these cases all tissue adja cent to the IMA was divided. In 68/262 patients (26 %) meticulous surgical technique was necessary based on a difficult or atypical lMA anatomy.
reason for rejection. In this special case complete mobilisation was not possihle. Modiflcation of surgical technique was perform ed in patients with lateral lMA origin. In these patients an IMA can be injured very easily at the level of the first rib . Futhermore it is necessary to free all tissue su rrounding the IMA to preven t tra ction and angulation. which may influence now (9. 19). Very meticulous prep ra tion of an IMA is necessary in cases with atypical or difficult anatomy (26 % in the present series). Large side br an ches. especially proximal bran ches near the IMA origin, are difficult to divide because of poor exposure. If not divided they may cause angulation and reduction ofl MA now.As report ed by others steal phenom enon due to enlarged side br anches may occur . with resulting recurrence of ang ina despite revasculari sation (17, 21. 22). Dissect ion of very tortu ous IMA's is difficult: these arte ries are more eas ily inju red during take-down . This stu dy has shown that preo perative angiog ra phy of IMA's may be performed during routine coro narography. without risk an d with minima l time -loss. to visua lise anomalies and that these are relatively common. may deteriorate IMAflow. and can influence su rgical st rategy . If the surgeon knows beforehan d what lMAanomalies he can expect he is given the opportunity to plan a safer surgical strategy. Referen ces 1
Discussio n
The IMA has heen shown to be the conduit with the grea test longevity among those curren tly available for CABG (7. 9. 16.25). To increase the number of acceptable grafts more emphasis shou ld be given on obta ining an IMA in good condition. Various factors a re known to influence IMA now. One can distinguish a natomical factors (anomali es. small caliber. sclerotic lesions) (7.16.21 -23) functional factors (proximal subclavian sten osis. drugs. spastic tend ency) (1. 2.4, 5. 8. 11. 12. 13, 15. 16. 19. 20. 26. 27) and technical factors (6.16.19). Meticulous surgica l tech nique and knowledge of IMA anatomy a re important factors in improving the number of availab le arte ries . Evalua tion of IMA anatomy is possihle hy preoperative angiography. Therefore sev eral authors recommend preoperative aortic arch ang iograp hy prior to CABG (5, 18. 23). Vein instead of an IMA was used in cases with a cornmon origin of thyreocervical trunk (TCT) and costocerv ical trunk (CCT) with IMA: in these cases occurrence of stea l phenom enon between coronary arte ries an d TCT is possible. especially in cas es with reduced coronary run -off, To divide TCT a supraclavicular.approach would be necessary as described in a case report from our clinic (24). Arteriosclerosis and spas ticity of an IMA were other reasons for not usin g it. Sclerotic lesions of IMA's are ra re: they are mostly depend ent on patients' age (10.14.23). Spastic IMA'swhich might have a detremental elTect on now are rarely found in angiograms. An accurate grading of spasticity is difficult preoperatively. and angiog raphic observation of an IMA spasm has rarely been documented (11). The refore. intraoperative measu rements of gra ft flow is recommended by some authors (4. 6). Atypical course of an IMA in combination with common origin of TCT and CCT was anothe r
2
3
~ 5
6
7
8
9
10
II
12
13
14
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Erwin P. Bauer MD
Clinic for Cardiovascular Surgery University Ilosp ita l Hamlstralle 100 Ch-809 1 Zurich/Switzerland Downloaded by: National University of Singapore. Copyrighted material.
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