Myocardial ischemia caused by postoperative malfunction of a patent internal mammary coronary arterial graft Kenne th Granke, MD,* Cl i f ford H . Van Meter , Jr., MD ,* Chr i s topher J. Whi te , MD,** John L. Ochsner , MD,* and Lar ry H . HoUier, MD,* New Orleans, La.

The internal mammary artery is used with increasing frequency for myocardial revascu- larization. However, preoperative coronary angiography does not always provide adequate visualization of subclavian arteries. I f a proximal subclavian artery stenosis exists or develops in a patient who has myocardial revascularization with the internal mammary artery, graft malfunction can occur resulting in myocardial ischemia. We have identified four cases of internal mammary artery graft malfunction at our own institution and identified an additional 12 cases from the literature. These 16 cases are analyzed for age, sex, time of onset of symptoms, clinical findings, method of revascularization, and long- term follow-up. Sixty-three percent o f the patients were men, and the mean age was 52.9 +- 9.0 years. Onset of symptoms occurred after a mean interval of 25.1 months from the time of myocardial revascularization. Three patients had asymptomatic reversal of flow in the internal mammary artery as diagnosed by coronary arteriography during routine follow-up examination before 1980. One death after internal mammary artery- coronary bypass grafting was related to immediate malfunction. In the remaining 12 patients with symptomatic malfunction, all but one were treated by placement of a carotid- subclavian bypass graft with no mortality. Relief of myocardial ischemia was complete in 93% of the patients with a mean follow-up of 29.3 months. Carotid-subclavian bypass grafting appears to be the treatment of choice for the usual management of internal mammary artery graft dysfunction. Careful preoperative evaluation and postoperative follow-up of the subclavian arteries, even by simple comparison of bilateral arm blood pressure should help reduce the incidence of this syndrome (J VAsc SURG 1990;11:659- 64.)

The first branch o f the subclavian artery is the internal mammary artery (IMA). Since Green et al.,1,2 first reported using the IMA as a conduit for myo- cardial revascularization in 1967, it has been used with increasing frequency. I f proximal subclavian ar- tery disease coexists or develops in a patient who had myocardial revascularization with an in situ IMA, myocardial ischemia can occur. Reversal o f flow in the IMA with a proximal occlusive lesion o f the sub- clavian artery has been termed "IMA steal. ''3,4 Since myocardial ischemia can occur without reversal o f the flow, and theoretically since any restrictive lesion o f the proximal subclavian artery can reduce flow to the IMA graft, then perhaps a more precise term

From the Departments of Surgery* and Cardiology ~* Alton Ochsner Medical Institutions.

Presented at the Thirteenth Annual Meeting of the Midwestern Vascular Surgical Society, Chicago, Ill., Sept. 29-30, 1989.

Reprint requests: Larry H. Hollier, MD, 1516 Jefferson Highway, New Orleans, LA 70121.

24/6/19228

would be IMA graft malfunction (credit to the edi- tors) for this unusual postoperative complication. We have identified at our own institution four cases of myocardial ischemia caused by proximal subclavian artery lesions and analyzed an additional 12 cases o f "IMA graft malfunction" from the literature? ~3

P A T I E N T S A N D M E T H O D S

Sixteen cases o f IMA graft malfunction are ana- lyzed for age, sex, time of onset of symptoms, clinical findings, type o f operative procedure for correction, and long-term follow-up? 13 Four of these cases were identified among 79 cases o f subclavian artery re- construction performed at our institution from 1962 to 1988; the 12 additional cases were found in the literature. Fisher's exact test and unpaired Student's test of means were used to identify significant dif- fcrcnces (p < 0.05).

Case 1. A 54-year-old man, who 4 years earlier had three autogenous vein aortocoronary bypass grafts to the left anterior descending, diagonal branch, and marginal

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Vertebral A.--~ ~ ~ T h y ~ c e r v i c ~ / Trunk Proximal / ~ Tr Jnk-/~Clavic'e [ Subclavian/" / ~ ~ ~ I

Art e r ~ ' t ~ / ~ ~

A / A~F" "k'x Thyrocervical

ff"xJ~'~k Trunk /j--Catheter '/ / / / ,] ( F - - D i s t a l

/ / [ . \ [ S u b c l a v i a n

/ / Vein ~C~ "~ Artery

/ 17_ ,. ooa,

Fig. l . Angiogram of patient with left IMA graft malfi,mction. A, Proximal subclavian artery stenosis; B, Filling of the subclavian artery from the IMA.

branch, came to the emergency department with crescendo angina and a myocardial infarction in progress. Coronary angiography showed occluded grafts and was complicated by cardiogenic shock with an end-diastolic left ventricular pressure of 35 mm Hg. Support with an intraaortic balloon pump was started, and myocardial revascularization was performed. Blood pressures were not taken bilaterally in the arms. At surgery the left IMA was harvested in situ, found to have adequate flow (60 ml/min) and was anas- tomosed to a large first diagonal branch; two other autog- enous vein grafts were anastomosed to the right coronary and circumflex artery. After operation the patient did well and was discharged home on the seventh day without com- plications.

For the first 2 months after discharge the patient was able to walk more than 1 mile per day and never complained of chest pain. Exertional chest pain and left arm pain then

developed when he walked less than one half mile. On physical examination the bilateral brachial arm pressures revealed a systolic blood pressure 50 mm H g higher in the right arm than in the left. Angiography via a transfemoral approach with the Seldinger technique showed an 80% proximal subclavian artery stenosis with reversal of flow through the IMA (Figs. 1A and B). Initially the left IMA filled antegrade from the pressurized injection of contrast, but then the left LMA filled the subclavian artery. The patient continued to have evidence of myocardial ischemia (inverted T waves) on the electrocardiogram in leads V~-V~. A left carotid-subclavian bypass graft with an 8 mm Dacron graft and supraclavicular incision was placed while the patient was under general anesthesia. The elec- trocardiogram normalized after operation, and the patient has remained free of symptoms for the past 10 months. No postoperative angiogram was obtained.

Volume 11 Number 5 May 1990 Internal mammary arterial graft malfunction 661

Case 2. A 62-year-old woman, 7 years after myocardial revascularization with a left IMA in situ graft to the cir- cumflex artery and vein grafts to the right coronary and diagonal branch, came to a local physician with exertional chest pain thought to be stable angina pectoris. Her symp- toms neither improved nor worsened with empirical med- ical management over the next 3 months. On referral for further evaluation and treatment the following were dis- covered: an absent left radial pulse, a brachial artery pres- sure difference of 90 mm H g between the two arms, and ischemic changes on the electrocardiogram leads V4 through V6 (ST segment depression). Coronary artery catheterization revealed total occlusion of the proximal left subclavian artery and reversal of flow in the IMA with a 99% proximal stenosis of the one remaining patent vein graft to the right coronary artery. With the patient under general anesthesia, revascularization was accomplished with a left carotid-subclavian bypass graft by means of an 8 mm Dacron graft and a supraclavicular incision. This corrected the symptoms as well as the ischemic changes noted on the preoperative electrocardiograms.

A repeat coronary catheterization on the fourth post- operative day was successful for a balloon angioplasty of the right coronary artery graft and revealed forward flow in the left IMA. The patient was discharged the next day, and she has done well without any recurrence of symptoms or electrocardiographic evidence of ischemia over the past 4V2 years.

Case 3. A 48-year-old man was admitted with an acute anterior inferior myocardial infarction. Coronary artery catheterization revealed surgically reconstructible coronary artery disease. The bilateral brachial artery pressure differ- ence was only 6 mm Hg, and the presence or absence of clavicular bruits was not mentioned. Aort0coronary bypass surgery was performed with two vein grafts to the right coronary and circumflex arteries. The left IMA was anas- tomosed in situ to the left anterior descending coronary artery. His recovery was uneventful, and the patient did well for 2 months after discharge. Recurrent chest pains at rest and an atrial arrhythmia then developed. Physical examination at this time showed a brachial artery pressure difference of 40 mm H g and a left supraclavicular bruit. Coronary artery catheterization revealed all previous grafts to be patent, a 75% stenosis o f the proximal left subclavian artery, and flow reversal in the IMA graft. The IMA graft malfimction was corrected with a left carotid-subclavian bypass graft by use of an 8 mm Dacron graft placed via a supraclavicular incision while the patient was under general anesthesia. The patient was discharged on the third post- operative day without complications. He was followed for 6 years with electrocardiograms and clinical examinations without evidence of myocardial ischemia.

Case 4. This final case represents myocardial ischemia associated with a right IMA graft malfunction caused by 'an iatrogenic proximal right subclavian lesion associated with nonocclusive atherosclerotic disease. A 47-year-old woman underwent single vessel myocardial revasculariza- tion wherein the right IMA was anastomosed to the right coronary artery. She came for treatment 3 years latcr with

a 1-year history of stable angina pectoris. Coronary artery catheterization from a left brachial artery approach was unsuccessfill because of presumed atherosclerotic disease of the right subclavian artery and the inherent difficulty encountered with this approach. Eventually an intimal dis- ruption occurred, and the right IMA graft was not visu- alized. Subsequently for 2 years her chest pains increased and were directly related to increased use of the right arm. Myocardial ischemia was noted in leads 1, 2, and aVF on the electrocardiogram. A bilateral brachial artery pressure difference of 10 mm H g was noted along with a r igh t supraclavicular bruit on physical examination.

Transfemoral arch aortography revealed a pseudo- aneurysm of the proximal right subclavian artery, and flow in the IMA could not be clearly identified. Reconstruction of the right subclavian artery was successfully undertaken by means of a partial median sternotomy, which was ex- tended laterally into the right chest above the clavicle and through the third intercostal space to form a "trap-door" incision. The first rib was resected, and a 6 mm Dacron graft was interposed into the proximal right subclavian artery, and the orifice of the IMA was preserved. After the operation the patient did well and was discharged home on the fifth postoperative day. Her electrocardiogram showed no more ischemic changes, and clinically no symp- toms of myocardial or right upper arm ischemia have been noted over the past 8 years. The right radial pulse and right brachial artery pressures were equal to the left.

LITERATURE REVIEW

Twelve cases o f I M A graft malfunct ion were pre- viously repor ted in the literature. (Table I). One death occurred intraoperat ively when an in situ I M A graft was pe r fo rmed in the presence o f a modera te stenosis in the proximal subclavian artery, and three o ther patients w h o were free o f symptoms underwent prophylact ic carotid subclavian bypass graft ing for f low reversal in the IMA. The eight o ther cases had findings o f myocardial ischemia as a result o f I M A graft malfunction. All o f the previously repor ted cases that were reconstructed were confined to the left IMA, and carotid-subclavian artery bypass graft ing was the only opera t ion used to correct the malfimc- t ion (all o f which were due to uncompl ica ted ath- erosclerotic occlusive disease o f the proximal left sub- clavian artery). O n e case did no t demons t ra te reversal o f f low in a pa tent I M A despite angiography. 6

R E S U L T S

Sixteen cases o f IMA-gra f t dysfunction have been analyzed for age, gender, t ime to onset o f symptoms after in situ grafting, clinical findings, me thods o f operat ive correction, and longitudinal fol low-up pe- riod. One pat ient died on the opera t ing r o o m table immediate ly after I M A grafting, and long- te rm fol low-up data were no t stated for five patients.

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Tab l e I. Summary o f data o f patent IMA graft malfunct ion

Months to Original symptomatic/(asymptomatic)

No. Date reported operation diagnosis Confirmation Reconstruction

1. 1974 a LIMA-LAD (11) * Angiogram SV, CSB SV-RCA SV-LCFX

2. 19774 RIMA-RCA Immediate (death) Autopsy, flow reversal by f low None LIMA-LAD meter SV-DIAG

3. 1977 s RIMA-RCA (12) * Angiogram, IMA flow reversal 8 mm DACRON CSB LIMA-LAD

4. 1977 s RIMA-RCA (36) * Angiogram, EMA flow reversal SV, CSB LIMA-LAD

5. 19846 LIMA-LAD 14 Angiogram, no IMA flow re- Hypogastric artery, CSB versal,+ stress test, arm exer- cise angina

6. 19867 LIMA-LAD 16 Angiogram, IMA flow reversal, SV, CSB ECG changes

7. 1986 a LIMA-LAD 4 Angiogram, IMA flow reversal 6 mm PTFE CSB SV-RCA

8. 19869 LIMA-LAD 12 Angiogram, IMA flow reversal 6 mm PTFE CSB SV-DIAG SV-LCFX SV-RCA

9. i9871° LIMA-LAD 20 Angiogram, IMA flow reversal NS SV-M_ARG SV-MARG

10. 1988 n MVR 17 Angiogram, IMA flow reversal, NS LIMA-LAD ECG changes SV-LCFX SV-RCA

11. 198812 LIMA-LAD 4 Angiogram, IMA, flow reversal l0 mm Dacron CSB SV-PDA SV-MARG

i2. 1988 la LIMA-LAD i0 Angiogram, IMA flow reversal, 8 mm PTFE CSB SV-DIAG ECG changes SV-MARG SV-RCA

13. Present report LIMA-DIAG 2 Angiogram, IMA flow reversal, 8 mm Dacron CSB SV-RCA ECG changes SV-LCFX

14. Present report LIMA-LCFX 88 Angiogram, LMA flow reversal, 8 mm Dacron CSB SV-RCA ECG changes SV-DIAG

15. Present report LIMA-LAD 2 Angiogram, IMA flow reversal 8 mm Dacron CSB SV-RCA SV-LCFX

16. Present report RIMA-RCA 12 Angiogram, no I/viA flow re- 6 mm Dacron Interpo- versa/, ECG changes sition

LIMA, Left internal mammary artery; RIMA, right internal mammary artery; LAD, left anterior descending; RCA, right coronary artery; DIAG, diagonal branch; MARG, marginal branch; LCFX, left circumflex artery; MVR, mitral valve replacement; SV, saphenous vein; PTFE, polytetraflnoroethylene; CSB; carotid subclavian bypass; ECG, electrocardiogram; SX, symptomatic malfunction; ASX, asymptomatic malfimction; NS, not stated. ~Asymptomatic flow reversal. ++~Required additional bypasses. tClinical estimate

Overall, the mean age was 52.9 _+ 9.0 years, and the ages for each gender were no t significantly dif- ferent. The male to female ratio was 2 : 1. The mean t ime f rom myocardial revascularization to onset o f symptoms was 25.1 -+ 37.8 mon ths in the patients

with symptoms, wi th a range o f 2 to 88 months . Only two o f 12 patients had symptoms develop after 18 months . In all patients wi th dis turbed I M A

flow caused by atherosclerotic occlusive disease there was at least a 20 m m H g difference between the brachial arteries, and the mean difference was 38.6 m m H g -+ 20.2. Symptomat ic versus asymp-o tomatic brachial artery pressure differences were

43.3 + 5.8 and 37.4 +- 22.7 m m H g , respectively (p = NS). Myocardial ischemia, the p redominan t symptom, was relieved in all bu t one patient who

Volume 11 Number 5 May 1990 Internal mammary arterial graft malfunction 6 6 3

Follow-up Patient Graft~ Late (too) status status angina

6 Alive P a t e n t N o

0 D i e d P a t e n t

a s _ _ _ _ m

N S - - - - - -

2 7 Al ive P a t e n t N o

3 Alive P a t e n t N o

N S - -

N S - - - - - -

N S

21 Alive P a t e n t Yes ~

18 Alive P a t e n t N o

8 Alive P a t e n t N o

5 4 Alive P a t e n t N o

5 4 Alive P a t e n t N o

6 Al ive P a t e n t N o

9 6 Al ive P a t e n t N o

subsequently required further myocardial revascular- ization. One patient underwent an additional pro- phylactic balloon angioplasty of a previously placed vein graft. Synthetic grafts were used more than au- togenous (2 : 1) for carotid-subclavian bypass graft- ing, but patency was essentially the same whether autogenous or synthetic grafts were used. All grafts remained patent with a mean follow-up of 29.3 _+ 30.0 months.

DISCUSSION The first case of IMA graft dysfunction was dem-

onstrated in a patient with no symptoms who had

routine cardiac catheterization after IMA in situ grafting? Myocardial ischemia associated with a pa- tent IMA in situ graft is a rare complication, but it can occur either early or late after myocardial revas- cularization, and it may represent a distinct form of "myocardial-steal. "~4 This complication occurs when a proximal obstructive, restrictive lesion in the sub- davian artery either coexists or subsequently develops in a patient with a patent in situ IMA graft. Early occurrences suggest clinically detectable disease may have been missed before the coronary artery bypass grafting. However, two of the patients from our in- stitution had no preoperative clinical findings but still experienced ischemic symptoms less than I year after IMA grafting. This also occurred in at least two other cases previously reported.lZaa Late occurrences imply that an obstructive/restrictive lesion in the proximal subclavian artery developed after IMA grafting.

Physical examination is the most efficient screen- ing method available at present; a supraclavicular bruit with a significant difference'in blood pressure between the brachial arteries strongly suggests sub- davian artery stenosis. However, angiographic ste- nosis may still be present despite a normal physical presentation as a result o f a rich collateral network.

Noninvasive screening tools such as continuous wave Doppler may provide a useful adjunct to phys, ical examination. Ackerman et al.l~ evaluated contin- uous wave Doppler in the diagnosis and follow-up of subclavian stenosis. No false-positive findings (greater then 50% stenosis or total occlusion) were noted in his study. However, this study showed that 13% of the stenoses/occlusions were no longer de- tectable over a 2-year follow-up. With improvement, the continuous wave Doppler technique may prove to be an important tool both for screening and for use in the follow-up of those patients who undergo myocardial revascularization with an in situ IMA graft.

In this review and in the case reports from our institution ischemia and cerebral or upper extremity symptoms inconsistantly occurred before or after myocardial ischemia. Thus until better methods of noninvasive testing can be developed, combined cor- onary and brachiocephalic angiography is still the "gold standard" to record the existance or the po- tential for IMA graft malfimction. Some have rec- ommended that arteriograms be obtained in selected patients, ranging from only those who have symp- toms to only those with diffuse peripheral occlusive disease or to all patients having coronary artery cath- eterization. 3'5'6,8 Coronary artery catheterization can easily be expanded to include the subclavian artery takeoff with little increase in cost or morbidity,

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Arguments against routine arch aortography are (1) the incidence of concomitant subclavian artery stenosis in patients undergoing coronary artery by- pass grafting is low (0.5% to 1.1%), 13 (2) the de- velopment of symptomatic coronary-IMA graft mal- function is estimated at only 0.44%, s and (3) there is no absolute correlation between the lesion and a pathophysiologic effect, since a 60% subclavian ste nosis can still allow 108 ml/min flow in the IMA. 16

Once symptoms of myocardial ischemia are rec- ognized after IMA grafting, angiography is essential to document graft patency and to rule out proximal subclavian artery disease. In the patients with symp- toms as well as in those who are free of symptoms (3 of 12 previously reported cases) revascularization of the myocardium by bypassing or reconstructing the subclavian artery lesion should be done. The pre- ferred technique for subclavian artery myocardial re- vascularization, and the only route noted previously in the literature, has been carotid-subclavian artery bypass grafting with synthetic or autogenous vein grafts. There is an excellent patency rate with syn- thetic materials, few operative risks aside from infec- tion, and excellent durability. ~7,18 Transposition of the subclavian artery onto the common carotid artery is feasible but may jeopardize the IMA graft and the myocardium. Percutaneous balloon angioplasty has been reported in proximal stenoses of the subclavian artery but is unproven and therefore not recom- mended at this time. ~v The only reported case of pseudoaneurysmal disease contributing to the mal- function, as reported in case 4, was corrected with an interposition graft of Dacron without injury to the IMA or myocardium, but it would not be rec- ommended for the usual obstructing proximal sub- clavian artery stenosis.

Before carotid-subclavian bypass grafting, it is useful to document the lack of carotid disease prox- imal to the donor site to avoid carotid steal. 2° Since physical findings are most useful as screening tools, and since proximal subclavian artery obstructive atherosclerotic lesions are unpredictable, frequent follow-up with bilateral brachial pressures are rec- ommended before and after myocardial revascular- ization with an IMA in situ graft.

REFERENCES

1. Green GE. Editorial: internal mammary bypass grafts. Ann Thorac Surg 1975;20:716.

2. Green GE, Stertzer SH, Gordon RB, Tice DA. Anastomosis of the internal mammary artery to the distal left anterior descending coronary artery. Circulation 1969;38:40(suppl 3):95.

3. Ha0ola PT, Vaile M. The importance of aortic arch or sub- clavian angiography before coronary reconstruction. Chest 1974;66:436-8.

4. Brown AH. Coronary steal by internal mammary graft with subclavian stenosis. J Thorac Cardiovasc Surg 1977;73: 690-3.

5. Tyras DH, Barrier HB. Coronary-subclavian steal. Arch Surg~ 1977;112:1125-7.

6. Bashour TI', Crew J, Kabbani SS, Ellertson D, Hanna ES, Cheng TO. Symptomatic coronary and cerebral steal after internal mammary-coronary bypass. Am Heart J 1984; 108:177-8.

7. Niemiera ML, Haft JI, Goldstein JE, Hobson RW. Retro- grade internal mammary artery flow and resistant angina pec- toris: clues to the coronary-subclavian steal syndrome. Cathet Cardiovasc Diagn 1986; 12:93-5.

8. Tarazi RY, O'Hara PJ, Loop FD. Symptomatic coronary- subclavian steal corrected by carotid-subclavian bypass.

VAsc SUR6 1986;3:669-72. 9. Byrnes JF. Case report: LAD-LIMA steal syndrome. Asso-

ciation Physicians Assistant CV surgery 1986;5:9-10. 10. Valentine RJ, Ery RE, Wheelan KR, Fisher DF, Jr, Clagett

GP. Coronary-subclavian steal from reversed flow in an in- ternal mammary artery used for coronary bypass. Am J Card 1987;59:719-20.

11. Mclvor ME, Williams GM, Brinker ]'. Subclavian-coronary steal through a LIMA-to-LAD bypass graft. Cathet Cardio- vase Diagn 1988;14:100-4.

12. Marshall WG Jr, Miller EC, Kouchoukos NT. The coronary- subclavian steal syndrome: report of a case and recommen- dations for prevention and management. Am Thorac Surg 1988;46:93-6.

13. Olsen CO, Dunton RE, Maggs PR, Lahey S}'. Review oi coronary-subclavian steal following internal mammary artery- coronary artery bypass surgery. Ann Thorac Surg 1988; 46:675-8.

14. Cheng TO. Left coronary artery-to-left ventricular fisvala: demonstration of coronary steal phenomenon. Am Heart J 1982;104:870-3.

15. Ackermann H, Diener HC, Seboldt H, Huth C. Ultrason- ographic follow-up of subclavian stenosis and occlusion: nat- ural history and surgical treatment. Stroke 1988; 19:431-5.

16. Geha AS, Krone RJ, McCormick IR, Baur AE. Selection of coronary bypass: anatomic, physiological and angiographic considerations of vein and mammary artery grafts. J Thorac. Cardiovasc Surg 1975;70:414.

I7. Ziomek S, Quifiones-Baldrich WI, Busuttil RW, Moore WS. The superiority of synthetic arterial grafts over autogenous veins in carotid-subclavian bypass. J VASC SUinG 1986;3: 140-4.

18. Barner HB, Kaiser GC, Willman WL. Hemodynamics of carotid-subclavian bypass. Arch Surg 1972;103:248-51.

19. Kachel R~ Endert G, Basche S, Grossmarm K, Glaser FH. Percutaneous transluminal angioplasty (dilation) of carotid, vertebral and innominate artery stenoses. Cardiovasc Inter- vent Radiol 1987;10:142-6.

20. Otis S, Rush M, Thomas M, Dilley R. Carotid steal syndrome following carotid-subclavian bypass. J VASC SUR6 1984;1: 649-51.