Iatrogenic left main and proximal right coronary artery stenoses after aortic valve replacement.

Abstract

We read with great interest the case report by Yavuz et al.[1] about a severe iatrogenic stenosis of the left main coron-ary artery (LMCA) and proximal right coronary artery(RCA) after direct instillation of cardioplegia into thecoronary ostia during an aortic and mitral valve replace-ments, 4 months earlier. We agree that this complicationmay be grossly underreported and may account for suddendeath or adverse outcome after aortic valve replacement(AVR). In a recently published retrospective study, datingfrom 1987 to present [2], seven cases of iatrogenic left maincoronary stenosis were observed at the Montreal Heart Insti-tute, after 2158 AVR, representing 0.3% of all the cases.The interval between AVR and symptoms ranged from 4 to11 months (mean: 7.3). The symptoms were usually severeunstable angina (5/7). The LMCA was involved in all caseswith the stenosis ranged from 55 to 75% and one occlusionand, the RCA in only two cases. Intermittent antegradecardioplegia had been used in three cases and continuousin four. The specific type of antegrade cannulation for cardi-oplegia, intermittent or continuous, may have some impor-tance, because no catheters have the potential of producingthe same trauma on the arterial wall.Our surgical research group has focused for a number ofyears on the investigation of endothelial function as amarker of surgical intimal injury, especially for assessmentof intracoronary devices such intracoronary shunts orcannulas to deliver cardioplegia or obtain hemostasis duringoff-pump coronary surgery, all of which can lead toendothelial dysfunction and chronic intimal hyperplasia[3]. In an experimental study, shunts were shown to createa severe endothelial dysfunction [4], due to the rubbing.However, the hydrodynamic pressure of the cardioplegiainstilled may also play an additional role in creating injury.Various systems have been developed such as simpleintra coronary cannulas for intermittent cardioplegia, stiffor soft, which may create intimal lesions by rubbing, andcannulas with occlusive balloons for continuous cardiople-gia to avoid repositioning and withdrawal which exert aconstant transmural pressure on the arterial wall, creatingtrauma which may be deleterious over the period of timenecessary for an AVR. The safest technique for morpholo-gical and functional preservation of the coronary arteryendothelial and muscular layers remains to be established,but the smallest soft catheters inserted gently with intermit-tent administration of cardioplegia at low pressure (,100mmHg) should be the preferred choice, if antegrade cardi-oplegia is necessary.Direct cannulation of the coronary ostia remain veryfrequently used by surgeons during AVR and ascendingaortic procedures. However, because of the risks describedabove, use of intracoronary cannulas to deliver cardioplegiamust always be guided by the concern of inducing as littletrauma as possible. Considering the pitfalls and dismalresults of myocardial revascularization for iatrogenicLMCA stenosis after AVR [2], emphasis on prevention ofthis complication with systematic use of the retrograde routeand judicious selective application of antegrade cathetersremains of paramount importance.References