European Heart Journal (1987) 8, 1346-1350

Flow reversal in coronary collaterals

P. URBAN, B. MEIER AND L. FINCI

Cardiology Centre, University Hospital, 1211 Geneva 4, Switzerland

KEY WORDS: Collaterals, coronary wedge pressure, angioplasty.

We report a case of collateral flow reversal observed seven months after angioplasty and due to the progressionof a second lesion in another vessel. Such an occurrence has not been reported previously in association withangioplasty. Its clinical implications are discussed.

Introduction

We report a case of a patient in whom collateralflow originating from the left anterior descendingcoronary artery was initially associated with a rightcoronary artery stenosis; seven months after suc-cessful angioplasty of the right coronary arterylesion, a severe left anterior descending stenosisdeveloped and induced reversed collateral flowfrom the right coronary artery through the samecollateral channel. Flow reversal in collaterals hasbeen shown to occur in an animal model1'1, followingsurgical bypass grafting121 and spontaneously inman'31. The present report documents flow reversalin pre-existing collaterals after angioplasty. It maybe a rare occurrence, but its clinical implications aresignificant.

Case report

A 40-year-old manual worker suffered an inferiormyocardial infarction in July 1985. Two monthslater, he underwent coronary angiography becauseof exertional angina with a positive stress test: therewas inferior hypokinesia of the left ventricle withan ejection fraction of 62% and an enddiastolicpressure of 11 mmHg. There was a high gradetandem stenosis in the vertical portion of the rightcoronary artery [Fig. 1 (a)] with collateral flow fromthe left anterior descending artery via a right ven-tricular marginal branch [Fig. 2(a)], and a proximalnon significant (30%) lesion on the left anteriordescending coronary artery. Two days after suc-cessful angioplasty of the right coronary artery

Submitted for publication on 8 January 1987 and in revised form 18May 1987.

Address/or correspondence- P. Urban M.D., National Heart Hospital,Westmoreland Street, London W1M 8BA. Telephone: (01)486 4433.

lesion, a repeat stress test was negative and thepatient was discharged symptom-free.

Seven months later, exertional angina recurredand a stress test was again positive. A repeat angio-gram showed a moderate (60%) restenosis of theright coronary lesion as well as a severe (90%)stenosis at the site of the previously non-significantlesion of the left anterior descending coronaryartery [Fig. l(b)]. Right to left collateral flow wasvisible through the same right ventricular marginalbranch that had previously served as a left to rightcollateral channel [Fig. 2(b)]. The left ventricle wasunchanged, and function in the territory of the leftanterior descending coronary artery appeared nor-mal at rest. Both arteries were successfully treatedby angioplasty. The coronary wedge pressure14' was35 mmHg in the left anterior descending artery butwas only 20 mmHg in the right coronary arteryafter angioplasty of the left lesion because theostium of the collateral marginal branch wasoccluded by the inflated balloon. At the end of theprocedure, complete disappearance of collateralflow was noted. A repeat stress test was negative,and the patient was again asymptomatic. At follow-up angiography six months later, both dilated sitesshowed good patency and the collateral channelwas not opacified in either direction (Fig. 3). Thepatient remained asymptomatic and the stress testnegative.

Comment

Collaterals have been shown to become angio-graphically visible in response to spasm, stenosis orocclusion'5"71. However, without sufficiently severecoronary stenosis no conclusions can be drawnfrom the absence of angiographically visible col-laterals, since they will only be apparent when the

0195-668X/87/I21346 + 05 $02.00,0 © 1987 The European Society of Cardiology

Flow reversal in collaterals 1347

(a)

(b)

Figure 1 (a) 30° right anterior oblique view of the right coronary artery showing theinitial high grade tandem stenosis (arrows) at the time of left to right collateral flow,(b) 30° right anterior oblique view with 30° caudal tilt showing severe proximal stenosisof the left anterior descending coronary artery (arrow) at the time of reversed right toleft collateral flow

gradient across them generates sufficient flow.This gradient is transiently increased by ballooninflation during angioplasty, and collaterals havebeen shown by contralateral injection to thenbecome visible'4'8'. This collateral flow has beencalled 'recruitable' and its existence can be pre-

dicted by an elevated coronary wedge pressuredistal to the treated lesion'4'. Coronary wedgepressure is the pressure recorded distal to astenosis while the inflated balloon occludes thecoronary artery. Its level varies with aortic pressurebut for patients in a stable haemodynamic state it is

1348 P. Urban, B. Meier and L. Find

essentially determined by the collateral flow reach-ing the artery distally to the lesion'491. One of thelimitations of coronary wedge pressure measure-ment is illustrated by the present case: because the

collateral channel opened into the right coronaryartery immediately distal to the stenosis, flowthrough it was impeded during balloon inflationand this led to spuriously low values for the wedge

Figure 2 30° right anterior oblique view showing collateral flow (long arrow) in theright marginal branch (short arrows), (a) The vessel is filled from the left anteriordescending coronary artery before angioplasty of the right coronary artery. There is anon-significant stenosis of the proximal left anterior descending (arrowhead), (b) Sevenmonths later, the same collateral channel is filled from the right coronary artery andopacifies the distal left anterior descending artery (double arrowhead) because of thenow severe proximal left anterior descending coronary artery stenosis.

Flow reversal in collaterals 1349

(a)

Figure 3 Follow-up angiography six months after the second procedure, (a) 30° rightanterior oblique view of the right coronary artery, (b) 30° right anterior oblique view ofthe left anterior descending artery. No collaterals are now visible and there is norestenosis of either lesion

pressure in the right coronary, when comparedto the values obtained from the left anteriordescending coronary artery.

In the present case, progression of the lesion inthe left anterior descending coronary artery led tospontaneous flow reversal in a collateral branchthat had remained in a 'standby' state after theoriginal right coronary artery stenosis had been

treated with angioplasty. This illustrates the factthat preexisting collateral channels can be recruitedat a later stage by progression of coronary disease.The observed flow reversal has not been reportedpreviously in association with angioplasty. It con-firms the data obtained from patients after coron-ary artery bypass grafting suggesting that pressuregradients were the sole determinants of the

1350 P. Urban, B. Meier and L. Find

direction of flow in collateral channels'2'. Recently, acase of spontaneous flow reversal through collateralchannels after a follow-up of 6 years has beenreported'3'.

Evaluation of the degree of protection againstischaemia that is afforded by collateral flow is diffi-cult. Our patient had no change in his resting leftventricular function at rest despite the developmentof a severe proximal left anterior descending lesion.A coronary wedge pressure of 35 mmHg such aswas measured in the present case should maintainsignificant residual flow in the event of totalocclusion'4'.

Although Cashin el a/.'10' have reported a rate ofprogression of non-significant coronary lesions ofonly 3% during a 37 months follow-up, it has alsobeen shown that such moderate lesions may pro-gress to sub-total or total occlusion in a sudden andunpredictable manner1"', as was the case in ourpatient. Securing the potential of inverted collateralflow may occasionally constitute an added benefitof angioplasty, particularly when 'non-significant'lesions are seen in the vessel from which thecollaterals originate.

References[1] Daraiano RJ, Ungerleider RM, Lofland GK, Williams

JM, Quick G, Cox JL. Reversal of flow through chroniccoronary collateral vessels. J Surg Res 1981; 30: 544-52.

[2] See JR, Marlon AM, Feikes HL, Cosby RS. Effect of

direct revascularization surgery on coronary collateralcirculation in man. Am J Cardiol 1975; 36: 734-8.

[3] Thomas JD, Gundel WD. Myocardial preservation withalternative coronary artery occlusion and reversal offlow through collateral vessels. Cath Cardiovasc Diag1986; 12:327-9.

[4] Meier B, Luethy P, Find L, Steffenino GD, RutishauserW. Coronary wedge pressure in relation to spon-taneously visible and recruitable collaterals. Circulation1987; 75: 906-13.

[5] Elayada McAA, Mathur VS, Hall RJ, Ali Massumi G,Garcia E, de Castro MC. Collateral circulation incoronary artery disease. Am J Cardiol 1985; 55: 58-60.

[6] Schwarz H, LeiboffRH, Bren GB el at. Temporal evolu-tion of the human coronary collateral circulation aftermyocardial infarction. J Am Coll Cardiol 1984; 4:1088-93.

[7] Takeshita A, Koiwaya Y, Nakamura M, Yamamoto K,Torii S. Immediate appearance of coronary collateralsduring ergonovine-induced arterial spasm. Chest 1982;82.319-22.

[8] Rentrop KP, Cohen M, Blankc H, Philips RA. Changesin collateral channel filling immediately after controlledcoronary artery occlusion by an angioplasty balloon inhuman subjects. J Am Coll Cardiol 1985; 5: 587-92

[9] Urban P, Meier B, Find L, de Bruyne B, Steffenino G,Rutishauser W. Coronary wedge pressure: a predictor ofrestenosis after balloon angioplasty. J Am Coll Cardiol(in press).

[10] Cashin LW, Sanmarco ME, Nessim SA, BlankenhornDH. Accelerated progression of atherosclerosis in cor-onary vessels with minimal lesions that are bypassed. NEnglJMed 1984; 311: 824-8.

[11] Bruschke AVG, Wijers TS, Kolsters W, Landmann J.The anatomic evolution of coronary artery diseasedemonstrated by coronary angiography in 256 nonoperated patients. Circulation 1981; 63. 527-36.