Coronary Artery Crossing: A Case Report and Literature Review

Abstract

Background:

Coronary artery crossing (CACr) constitutes a rare but clinically relevant anomaly of intrinsic coronary arterial anatomy. Current literature on this subject comprises isolated case reports and one case series. The purpose of this report is to present all cases of CaCr that have been reported in the English literature, highlighting its clinical implications.

Case:

We present the case of a patient with intermittent chest discomfort associated with psychological stress and evidence of crossing between the left anterior descending (LAD) artery and the first diagonal artery (DgA) on invasive coronary angiography. Myocardial bridging was also noted in the mid LAD artery but not at the crossing point or any other crossing artery segments, and produced obstructive (≥50%) dynamic lumen compromise. The patient was discharged in good condition and was prescribed aspirin, a statin, and diltiazem.

Conclusions:

This review included 24 records that represented 27 patients, including the one presented in this report. The anomaly has been predominantly diagnosed in male patients and the diagnosis has predominantly been made using computed tomography coronary angiography. The most frequent CACr pattern revealed in 12 patients (44%) was a crossing between the LAD and left circumflex arteries while the second most frequent CACr pattern revealed in six patients (22%) was a crossing between the LAD artery and a DgA. There were five cases (19%) with evidence of an intramyocardial course, either at the point of vessel crossover or beyond that point. The crossing coronary arteries themselves were found to have atherosclerotic lesions in three patients (11%). Even though CaCr has not been associated with any clinical repercussions, cardiologists and cardiac surgeons should bear knowledge of this anomaly not only for diagnostic purposes when performing coronary artery angiograms but also in order to properly select and execute a revascularization procedure. Furthermore, CaCr may be associated with clinically relevant, functional coronary artery abnormalities such as spasm affecting the segments of the arteries crossing over each other or having an intramyocardial course. Unique patterns of coronary blood flow and wall shear stress may also be created at the crossover area, potentially increasing the risk of developing atherosclerosis.

Graphical abstract

Keywords

angiography / coronary anomalies / computed tomography / pathology / intramyocardial artery

1. Introduction

No crossing must exist between extramural arteries for a normal coronary arterial circulation [1]. Therefore, the existence of epicardial coronary arteries crossing each other en route to their dependent myocardial distributions, known as coronary artery crossing (CACr), is considered an anomaly in the intrinsic coronary artery anatomy [2]. CACr is considered benign because it has not been linked to specific clinical repercussions; however, CACr is a clinically relevant anomaly of which knowledge is valuable for both cardiologists and cardiac surgeons. This report presents a CACr case and an overview of all instances of this anomaly that have been reported in English literature, as far as we are aware. Our objective was to emphasize the clinical implications of CACr for diagnostic angiography and the selection and execution of revascularization procedures.

2. Case Presentation

A 44-year-old man with a history of arterial hypertension and hyperlipidemia presented with intermittent chest discomfort associated with psychological stress. The patient showed no ischemic electrocardiographic (ECG) changes, no biochemical evidence of myocardial infarction, and his echocardiogram was essentially normal. However, the treadmill exercise–ECG test results were equivocal, prompting us to perform coronary angiography (CA). The latter showed patent coronary arteries and crossing between the left anterior descending (LAD) artery and the first diagonal artery (DgA) (Fig. 1).

Specifically, the first DgA arose from the medial aspect of the ostial LAD artery and followed a short initial course medial to the LAD artery, before crossing the LAD artery to reach its dependent myocardial territory on the anterolateral aspect of the left ventricle distal to the area supplied by a second gracile DgA. Angiographic “milking” indicating myocardial bridging was noted in the mid LAD artery but not at the crossing point or any other crossing artery segments, and produced obstructive (\ge50%) dynamic lumen compromise. The patient was discharged in good condition and was prescribed aspirin, a statin, and the dihydropyridine calcium channel blocker diltiazem.

3. Discussion

The crossing of two epicardial coronary arteries, which was first reported in 1985, is considered a benign anomaly [2, 3]. However, a subsequent report indicated that this anomaly may have clinical significance when planning revascularization procedures [4]. Furthermore, a recent case has shown that the depiction of CACr between the LAD and left circumflex (LCx) arteries through conventional coronary angiography can be challenging, thereby highlighting the diagnostic implications this anomaly may have [5]. Therefore, we conducted a literature review search of the PubMed and Google Scholar databases, which covered all published CACr cases from 1985 to 2024, using the search algorithms shown in Fig. 2.

All titles and abstracts found in the initial search were screened. Overall, we included all literature describing crossing between epicardial (extramural) coronary arteries/branches, whether having a normal or anomalous origin in patients with a structurally normal or abnormal heart. The references of the selected publications were also assessed for additional literature that was not detected in the initial search. Finally, the articles citing the selected publications detected in the initial search or their selected references were also assessed for additional literature. Ultimately, 24 records representing 27 patients, including the one presented in this report, were included in this review. The cases have been arranged in chronological order of publication and are shown in Table 1 (Ref. [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]), along with their anatomical particularities.

The anomaly has been predominantly diagnosed in male patients (70%), with a mean age of 49.9 \pm 11.0 years, while the seven female patients had a mean age of 56 \pm 15.3 years (sex ratio of 2.7/1). Diagnoses have predominantly been made using computed tomography coronary angiography (CTCA; 59%), while conventional CA diagnosed 37% of the cases, and one case (4%) was diagnosed using anatomical pathology. The most frequent CACr pattern revealed in 12 patients (44%) was a crossing between the LAD and LCx arteries [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]. The LAD and LCx arteries arose from separate but adjacent ostia in the left aortic sinus in nine cases. The ostium of the LAD artery was always located posterior to the ostium of the LCx artery. In contrast, at the crossing point, which is always formed by the proximal segments of these vessels, the LAD artery was always superior to the LCx artery. Myocardial bridging of any of these vessels at the point of their crossover was not reported in any of these cases; however, the mid-LAD artery beyond the point of vessel crossover showed an intramyocardial course in two cases. The second most frequent CACr pattern revealed in six patients (22%) was a crossing between the LAD artery and a DgA [17, 18, 19, 20, 21, 26]. In two cases diagnosed by CTCA, the LAD artery crossed inferior to the DgA. The remaining instances concerned crossing between the LCx artery or the right coronary artery (RCA) and their branches, crossing between branches of the LCx artery or the RCA, and crossing between the LAD artery or an obtuse marginal branch (OMB) and a ramus medianus (RM) [3, 4, 22, 23, 24, 25]. There were five cases (19%) with evidence of an intramyocardial course, either at the point of vessel crossover or beyond that point. In one of these cases, both crossing OMBs showed an intramyocardial course. Furthermore, the crossing coronary arteries themselves were found to have atherosclerotic lesions in three patients (11%).

3.1 Clinical Significance of Coronary Artery Crossing

Although CACr has not been associated with specific clinical repercussions, knowledge of this anomaly is significant not only for practical purposes when performing coronary artery angiograms, but also for therapeutic purposes, because it may affect the accuracy of identifying the culprit lesion in cases of acute coronary syndrome and the choice and execution of revascularization procedures. The case of crossing LAD and LCx arteries arising independently from the left aortic sinus reported by Sen et al. [5] highlights the challenge of depicting this anomaly using conventional angiography. The authors were only able to demonstrate the LAD artery selectively; therefore, the authors obtained a non-selective view of the left coronary artery system in a left anterior oblique caudal projection, which showed that the LAD and LCx arteries had switched positions with the LCx artery depicted to the “left” of the LAD artery. The LCx artery was subsequently selectively engaged with a counterclockwise rotation, hence an anteriorly directed catheter. The anatomy was clarified through CTCA, which showed the crossing proximal courses of the LAD and LCx arteries, with the LAD artery arising posterior to the LCx artery. In cases of an absent left main coronary artery without crossing between the LAD and LCx arteries, the ostium of the LAD artery generally has a more anterior origin than the ostium of the LCx artery. Failure to selectively engage these vessels using the usual technique and catheters should alert the physician to the possibility of proximal crossing between them. Accordingly, suspicion of this specific anomaly should arise in case the ostium of the LAD artery is selectively engaged with a clockwise rotation, hence a posteriorly directed catheter, perhaps with a shorter secondary curve; thus, an upward pointing tip, such as a Judkins Left 3.5 catheter. Finally, the ostium of the LCx artery is selectively engaged with a counterclockwise rotation, hence an anteriorly directed catheter, perhaps with a longer secondary curve; thus, a more horizontal tip, such as a Judkins Left 4.5. Of course, a full depiction of the anomaly would require catheter engagement of the ostia of the LAD and LCx arteries and simultaneous visualization of these vessels.

Furthermore, in the case of acute coronary syndrome owing to an occlusion of a DgA leaving an avascular area at the anterolateral aspect of the left ventricle, the difficulty in identifying a stump-like thrombotic occlusion of a normally arising DgA across the LAD artery should alert the physician to the possibility of occlusion in a DgA arising proximal and contralateral to the origin of other diagonal branches and a crossing of the LAD artery. Therefore, knowledge of this specific anomaly facilitates the correct diagnosis and revascularization procedure. In patients with CACr who are potential candidates for surgical revascularization, the possibility of intramural coursing of significantly stenosed crossing branches needing revascularization should be investigated before surgery because intramural coronary branches, which may not be readily identifiable on conventional CA, are not amenable to bypass grafting. Adjunctive imaging modalities possess a higher sensitivity than invasive CA in detecting intramyocardial coronary arteries, such as CTCA, and may be employed for such a purpose. If a severely narrowed crossing coronary artery/branch cannot be bypassed because of its intramural course, the surgeon may create an arterio-arterial shunt at the point of the crossing, provided the other branch does not contain a flow-limiting stenosis. If this is not possible, stent angioplasty may be selected as a more suitable revascularization option, should leaving such intramyocardial branches unrevascularized be judged unacceptable. Of course, it is currently unknown whether any specific circumstances, currently unknown but potentially present in the area of vessel crossover, pose particular risks if stent angioplasty is performed in that specific area.

Although CACr has not been linked to specific clinical repercussions, it may be associated with clinically relevant, functional coronary artery abnormalities. However, to our knowledge, this potential association has yet to be investigated in any prior study. For example, in the clinical context of myocardial ischemia with non-obstructive (50%) coronary artery disease (CAD), demonstration of CACr should alert the physician to the possibility of spasm, to which crossing coronary arteries with an intramyocardial course are susceptible [20, 27]. Vascular tone testing with intracoronary acetylcholine would be required in such cases for diagnosis, management, and risk stratification purposes. Furthermore, whether the segments of the arteries at the crossover area are subject to mechanical stimulation from each other, inducing endothelial dysfunction and an enhanced local vascular reactivity to systemic vasoconstrictor stimuli, is currently unknown. An additional issue worthy of investigation is whether the abnormal anatomy of crossing LAD and LCx arteries is associated with unique patterns of coronary blood flow and wall shear stress, potentially increasing the risk of atherosclerosis development [28]. A long-term follow-up is necessary for such an investigation, which should be based on computational fluid dynamics. Yet, the patient with crossed LAD and LCx arteries reported by Sen et al. [5] and the patient with a single coronary ostium and crossed LAD artery and ramus medianus reported by Njeim et al. [23] did not experience any clinical events during a 2-year follow-up.

3.2 Developmental Considerations

Traditional knowledge teaches that proximal coronary artery stems develop following fusion of the multiple endothelial strands emerging from the aortic peritruncal plexus and penetrating the aortic wall of the facing sinuses [29]. Since it would be difficult to hypothesize an altered fusion process of the multiple endothelial strands that would result in the formation of crossing channels, the anomaly of crossing LAD and LCx arteries challenges this “ingrowth” model of proximal coronary artery stem development. Given newer evidence documenting that the coronary ostia and most proximal part of the coronary artery stems are formed by limited outgrowth of the aortic endothelium through endocardial sprouting, it may be considered more plausible that independent origin of the LAD and LCx arteries from the left aortic sinus with crossing between their more proximal segments results from a defective outgrowth mechanism [30].

3.3 Practical Approach to CACr

Overall, knowledge of the anomaly and being an astute observer are necessary to diagnose CACr accurately. However, diagnosing crossed LAD and LCx arteries arising from separate ostia remains challenging. Depicting the LCx artery to the “left” of the LAD artery in non-selective conventional angiography in a left anterior oblique caudal projection helps the physician suspect the anomaly [5]. Yet, catheter engagement of the ostia and simultaneous visualization of these vessels would be necessary to depict crossed proximal courses. Alternatively, the anomaly can be reliably defined through CTCA. Patients who present with myocardial ischemia and are diagnosed with CACr should have their angiogram scrutinized for signs of crossed coronary arteries with an intramyocardial course. Such a course is typically diagnosed via the angiographic “milking effect” and a “step down–step up” phenomenon induced by systolic compression of the tunneled segment. An intracoronary bolus dose of vasodilators, such as nitroglycerin or isosorbide dinitrate, can significantly improve diagnostic sensitivity. Yet, the presence of the “step down–step up” phenomenon without angiographic “milking” or a corkscrew appearance of either or both crossed coronary arteries should prompt investigation using CTCA to visualize an intramyocardial coronary artery course more sensitively and comprehensively than conventional angiography. In the case of non-obstructive (50%) CAD, irrespective of an intramyocardial course of the crossed coronary arteries, the patient could undergo spasm provocation testing. The occurrence of a spasm in a “bridged” segment of the crossed coronary arteries may entail a high risk of myocardial infarction and a worse long-term prognosis in general [27]. Such a diagnosis may inform treatment decisions, such as treating the patient with a calcium channel blocker and avoiding prescribing a beta-blocker, which may exacerbate coronary spasm, or nitrates. Indeed, nitrates will likely worsen the symptoms experienced by the patient owing to exacerbated myocardial bridge behavior secondary to decreased intrinsic coronary wall tension and increased reflex sympathetic stimulation of contractility. Conversely, suppose surgical revascularization is contemplated in a patient with obstructive (\ge50%) CAD also affecting the crossed coronary arteries. In that case, the surgeon should fully know the relevant anatomy to plan the procedure properly. In the event that a crossed coronary artery requires percutaneous revascularization for a stenosis at the area of vessel crossover, where specific circumstances may pose risks in the case of stent angioplasty, one may choose to proceed with angioplasty using drug-coated balloons.

4. Conclusion

We have presented an overview of all published CACr cases, a rare but clinically important anomaly in intrinsic coronary artery anatomy. This anomaly is presently considered benign. However, it is possibly associated with clinically relevant, functional coronary artery abnormalities such as a spasm in the area of vessel crossover or segments with an intramyocardial course; however, these have yet to be proven. Knowledge of the particularities of crossing LAD and LCx arteries, the most frequently encountered pattern, facilitates the correct diagnosis through conventional CA. However, the crossing of these arteries can be especially challenging to depict. This way, the erroneous diagnosis of ostial occlusion or absence of either of the two arteries is avoided. Meanwhile, knowledge of CACr also facilitates the identification of the culprit lesion during coronary angiography and, therefore, the revascularization procedure in patients presenting with acute coronary syndrome. Moreover, the CACr diagnosis should alert the physician to possible intramyocardial coursing of one or both crossing branches, something that should be considered when planning revascularization procedures, whether percutaneous or surgical. Computed tomography CA can not only reliably depict this anomaly but can also reveal the arterial spatial relationship at the point of crossover and depict any intramyocardial coursing that may not be apparent during conventional angiography.

Availability of Data and Materials

The data underlying this article are available in the article and in its online Supplementary Material.

References

[1] Angelini P. Normal and anomalous coronary arteries: definitions and classification. American Heart Journal. 1989; 117: 418–434. https://doi.org/10.1016/0002-8703(89)90789-8.

[2] Angelini P. Coronary artery anomalies: an entity in search of an identity. Circulation. 2007; 115: 1296–1305. https://doi.org/10.1161/CIRCULATIONAHA.106.618082.

[3] Muyldermans LL, Van den Heuvel PA, Ernst SM. Epicardial crossing of coronary arteries: a variation of coronary arterial anatomy. International Journal of Cardiology. 1985; 7: 416–419. https://doi.org/10.1016/0167-5273(85)90097-x.

[4] Bilazarian SD, Jacobs AK, Fonger JD, Faxon DP. Case report of a coronary anomaly: crossing obtuse marginal arteries. Catheterization and Cardiovascular Diagnosis. 1991; 23: 130–132. https://doi.org/10.1002/ccd.1810230215.

[5] Sen G, Veitch A, Nabais S. A case of the crossed coronaries. BJR Case Reports. 2020; 7: 20200143. https://doi.org/10.1259/bjrcr.20200143.

[6] Czekajska-Chehab E, Staśkiewicz GJ, Mazur-Stazka E, Drop A, Maciejewski R. An unusual crossed course of separately originating left circumflex and left anterior descending arteries with concomitant anomalies found in multi-slice computed tomography. Folia Morphologica. 2005; 64: 334–337.

[7] Hur J, Kim YJ, Nam JE, Kim TH, Choe KO, Choi BW. Anomalous origin of the left circumflex artery from the right coronary sinus with an interarterial course: diagnosis with multidetector row computed tomography. Journal of Thoracic Imaging. 2008; 23: 142–144. https://doi.org/10.1097/RTI.0b013e31815b8993.

[8] Shepard TF, Srichai MB, Kim D, Lim R, Jacobs JE. Aberrant crossed left circumflex and left anterior descending arteries: diagnosis with multidetector cardiac CT angiography. Journal of Computer Assisted Tomography. 2009; 33: 211–214. https://doi.org/10.1097/RCT.0b013e318173f081.

[9] Continentino MA, Freitas AMRF. Crossing coronary arteries. Arquivos Brasileiros De Cardiologia. 2011; 96: e76.

[10] Pursnani A, Jacobs JE, Saremi F, Levisman J, Makaryus AN, Capuñay C, et al. Coronary CTA assessment of coronary anomalies. Journal of Cardiovascular Computed Tomography. 2012; 6: 48–59. https://doi.org/10.1016/j.jcct.2011.06.009.

[11] Murphy DJ, Keraliya AR, Aghayev A, Steigner ML. Interarterial Left Circumflex: The Forgotten Coronary Artery Anomaly. Irish Medical Journal. 2017; 110: 501.

[12] Pereira MAF, Ribeiro WN, Demarchi LMMF. Case 2/2019 - Man with Arrhythmogenic Cardiopathy Followed by Rapidly Progressive Heart Failure. Arquivos Brasileiros De Cardiologia. 2019; 112: 466–472. https://doi.org/10.5935/abc.20190065.

[13] Michalak KW, Wernovsky G, Moll M, Anderson RH. The black swan: Unique coronary arterial anatomy observed in a patient with transposition. The Journal of Thoracic and Cardiovascular Surgery. 2019; 158: e107–e109. https://doi.org/10.1016/j.jtcvs.2019.03.087.

[14] Schulze-Zachau V, Brantner P, Zellweger MJ, Haaf P. Proximal crossing of the left coronary arteries with a septal branch arising from the left circumflex artery. European Heart Journal. Case Reports. 2020; 4: 1–2. https://doi.org/10.1093/ehjcr/ytaa273.

[15] O’Brien H, Duerden L, Hudson BJ, Rodrigues JCL. Cross my heart: A rare case of anomalous coronary artery anatomy. Journal of Cardiovascular Computed Tomography. 2020; 14: e145–e146. https://doi.org/10.1016/j.jcct.2019.10.005.

[16] Ferraz Costa G, Costa M, Teixeira R. ‘X-cross’ left coronary artery congenital anomaly. European Heart Journal. Case Reports. 2023; 7: ytad296. https://doi.org/10.1093/ehjcr/ytad296.

[17] Yilmaz H, Demir I. Images in cardiology: crossing epicardial coronary arteries. Heart (British Cardiac Society). 2005; 91: 1523. https://doi.org/10.1136/hrt.2005.066480.

[18] Andreou AY, Kyprianou D, Eteocleous N, Theodorou S, Avraamides PC. A case of crossing coronary arteries. Journal of Cardiovascular Medicine (Hagerstown, Md.). 2012; 13: 332–333. https://doi.org/10.2459/JCM.0b013e3283528f5b.

[19] Okutucu S, Karakulak UN, Kabakcı G, Aytemir K. An unusual cause of chest pain: Acute coronary syndrome following administration of ergotamine tartrate. Experimental and Clinical Cardiology. 2012; 17: 43–44.

[20] Pandey NN, Sharma A. A curious case of crossing coronary arteries. Asian Cardiovascular & Thoracic Annals. 2020; 28: 219. https://doi.org/10.1177/0218492320901926.

[21] de Jong JJD, Tent H. Coronary crossing. Netherlands Heart Journal: Monthly Journal of the Netherlands Society of Cardiology and the Netherlands Heart Foundation. 2021; 29: 172. https://doi.org/10.1007/s12471-020-01524-9.

[22] Zegers ES, Verkroost MWA, Verheugt FWA. Crossing coronary arteries. Netherlands Heart Journal: Monthly Journal of the Netherlands Society of Cardiology and the Netherlands Heart Foundation. 2007; 15: 155–156. https://doi.org/10.1007/BF03085973.

[23] Njeim M, Nasr Y, Younes M, Song TK, Koenig GC, Nour K. Single coronary ostium in right coronary sinus: previously unreported “one for all” configuration. Texas Heart Institute Journal. 2014; 41: 601–602. https://doi.org/10.14503/THIJ-13-3806.

[24] Michałowska AM, Tyczyński P, Kruk M, Witkowski A, Michałowska I. Crossing of coronary arteries. Kardiologia Polska. 2018; 76: 1021. https://doi.org/10.5603/KP.2018.0121.

[25] Ndao SCT, Zabalawi A, Taldir G. Entwined Pattern of Coronary Arteries. CJC Open. 2020; 3: 127. https://doi.org/10.1016/j.cjco.2020.09.006.

[26] Andreou AY. Letter to the editor. Experimental and Clinical Cardiology. 2012; 17: 155.

[27] Montone RA, Gurgoglione FL, Del Buono MG, Rinaldi R, Meucci MC, Iannaccone G, et al. Interplay Between Myocardial Bridging and Coronary Spasm in Patients With Myocardial Ischemia and Non-Obstructive Coronary Arteries: Pathogenic and Prognostic Implications. Journal of the American Heart Association. 2021; 10: e020535. https://doi.org/10.1161/JAHA.120.020535.

[28] Wei Y, Cao H, Zheng T. The Association Between the Hemodynamics in Anomalous Origins of Coronary Arteries and Atherosclerosis: A Preliminary Case Study Based on Computational Fluid Dynamics. Bioengineering (Basel, Switzerland). 2024; 11: 1196. https://doi.org/10.3390/bioengineering11121196.

[29] Ando K, Nakajima Y, Yamagishi T, Yamamoto S, Nakamura H. Development of proximal coronary arteries in quail embryonic heart: multiple capillaries penetrating the aortic sinus fuse to form main coronary trunk. Circulation Research. 2004; 94: 346–352. https://doi.org/10.1161/01.RES.0000112963.79064.09.

[30] Tomanek R, Angelini P. Embryology of coronary arteries and anatomy/pathophysiology of coronary anomalies. A comprehensive update. International Journal of Cardiology. 2019; 281: 28–34. https://doi.org/10.1016/j.ijcard.2018.11.135.