Patient-Specific Three-Dimensional Aortocoronary Model for Percutaneous Coronary Intervention of a Totally Occluded Anomalous Right Coronary Artery

Abstract: Percutaneous coronary intervention (PCI) for anomalous coronary arteries is often difficult because the support provided by the guide catheter is insufficient. We encountered a patient with severe three-vessel coronary disease including a totally occluded anomalous right coronary artery (RCA) originating from the left sinus of Valsalva. Initial PCI for the anomalous RCA via the transradial approach failed. Therefore, we constructed a three-dimensional (3D) aortocoronary model and conducted an in vitro simulation to plan the second PCI and found that a Judkins left (JL) 3.5 guide catheter in the power position yielded maximum back-up support for the anomalous RCA. Thus, the second PCI was conducted using an 8 Fr JL 3.5 guide catheter in the power position via the transfemoral approach. The procedure was smooth and successful, without any adverse events. Our experience suggests that case-specific 3D models are useful for strategic planning of complex PCIs.

J INVASIVE CARDIOL 2015;27(7):E139-E142

Key words: cardiac imaging, three-dimensional model, percutaneous coronary intervention

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Coronary artery anomalies are rare congenital abnormalities observed in approximately 1% of all patients undergoing cardiac catheterization.^1,2 Percutaneous coronary intervention (PCI) for an anomalous right coronary artery (RCA) can be challenging because it is often difficult to obtain sufficient guide catheter support. Here, we present a case of successful PCI for a totally occluded anomalous RCA originating from the left sinus of Valsalva, in which a patient-specific three-dimensional (3D) model was utilized for preprocedural planning.

Case Report

A 64-year-old woman complained of angina during a hospital admission for treatment of diabetes mellitus. Coronary computed tomographic angiography (CCTA) showed three-vessel disease with a totally occluded RCA originating from the left sinus of Valsalva. The left anterior descending (LAD) and left circumflex (LCX) arteries also had multiple severe stenoses. Although coronary bypass surgery is generally recommended for diabetic patients with three-vessel disease,³ we selected PCI due to patient preference.

Coronary angiography (CAG) via the left radial artery confirmed the presence of multiple severe stenoses in the LAD and LCX arteries. Right coronary angiography performed using an Amplatz left (AL) 1.0 diagnostic catheter confirmed that the RCA originating from the left sinus of Valsalva was totally occluded (Figure 1). Initially, RCA revascularization was attempted. Engagement of the RCA using several 6 Fr guide catheters including the AL 1.0, 1.5, and 2.0 and EBU 4.0 catheters (Launcher; Medtronic) was attempted but failed. A Judkins left (JL) 3.5 (Mach1; Boston Scientific) was then used to engage the left coronary artery (LCA). A Sion Blue guidewire (Asahi Intecc) was placed in the LAD, and another Sion Blue guidewire was crossed to the mid-RCA after the JL 3.5 guide catheter was slightly detached from the LCA ostium. However, further advancement of the guidewire with the help of a microcatheter including a 4.5 Fr CoKatte catheter (Asahi Intecc) failed because of insufficient guide catheter support. Further intervention was suspended to avoid contrast medium waste and unnecessary radiation exposure.  

To plan the second PCI, a 3D aortocoronary model was constructed and an in vitro simulation was conducted (Figure 2). The 3D model was created using laser stereo lithography on the basis of the patient’s CCTA data and was composed of polyurethane (crossEffect, Inc). The model simulated the inner surface of the ascending aorta and coronary artery. The model was created within 1 week of submitting the CCTA data. A 30-mm diameter polyvinyl chloride tube (mimicking the descending aorta) was connected to the 3D model. A 7 Fr introducer sheath was inserted in the polyvinyl chloride tube 50 cm distal to the coronary artery. The simulation mimicked the transfemoral approach. Two experiments were conducted for procedural planning. The first experiment was conducted to identify the correct guide catheter that could be engaged for maximum support under fluoroscopy (Figure 3). Several 7 Fr guide catheters were examined: AL 1.0, AL 1.5, and AL 2.0; JL 3.0, JL 3.5, and JL 4.0; and EBU 3.5 and EBU 4.0 (Mach1; Boston Scientific), but none were useful for selective cannulation of the anomalous RCA and maintenance of coaxial position. However, when the JL 3.5 guide catheter was pushed to form a loop in the left sinus of Valsalva, its tip became coaxial to the ostium of the anomalous RCA, and it seemed to provide the maximum guide support in this “power” position. The second experiment was conducted to quantify the support of the guide catheters (Figure 4). First, the 3D model and 30 mm polyvinyl chloride tube were soaked in a tank filled with water at 37 °C. Second, the guide catheter was engaged in the anomalous RCA, and a hydrophilic Whisper MS guidewire (Abbott Vascular) was advanced to the distal RCA. Third, a 2.0 x 20 mm Ikazuchi balloon catheter (Kaneka Medical Products) was slowly advanced at a rate of 1 mm/s using an electronically controlled slider until the guide catheter was disengaged from the anomalous RCA. Fourth, the force applied to the Ikazuchi balloon catheter was measured using a load meter, and the maximum force applied to the balloon catheter was considered the maximum support provided by each guide catheter. Four 7 Fr guide catheters were examined, namely, JL 3.5 in the normal position, JL 3.5 in the power position, AL 1.5, and KL 3.0 (Mach1, Boston Scientific). The JL 3.5 in the power position showed the maximum support of 136 g. Therefore, JL 3.5 in the power position was considered for use in the second PCI, to obtain the maximum support. 

The second PCI was performed by the same operator 4 weeks after the first PCI. An 8 Fr guide catheter was introduced via transfemoral approach in preparation for the retrograde approach when the antegrade PCI failed. After engagement of an 8 Fr Launcher JL 3.5 guide catheter (Medtronic) in the LCA ostium, a Sion Blue guidewire was placed in the distal LAD. Then, a Sion Black guidewire (Asahi Intecc) with an Excelsior microcatheter (Boston Scientific) was advanced to the distal RCA, and the Sion Blue guidewire in the LAD was pulled out. Predilatation was performed in a stepwise manner using a 1.0 to 2.5 mm balloon catheter. After the JL 3.5 guide catheter was advanced to the power position, two Promus premier stents (2.25 x 32 mm and 2.5 x 32 mm; Boston Scientific) were implanted (Figure 5). Postdilatation of the stents with a 2.5 x 15 mm Raiden3 non-compliant balloon catheter (Kaneka Medical Products) showed good angiographic results. Subsequently, PCI was performed for the LAD and LCX stenoses. Two Promus premier stents were implanted in the LAD, and one Promus premier stent was implanted in the LCX. Postoperatively, the patient’s symptoms resolved, and she was discharged 4 days after the second PCI.

Discussion

Coronary artery anomalies affect approximately 1% of the general population,^1,2 and anomalous RCAs originating from the left sinus of Valsalva are even more rare, representing only 0.11% of the population and 8% of the total anomalies present.² PCI for an anomalous RCA can be technically challenging because guide catheter support is often suboptimal. Thus, proper guide catheter selection is a key factor for successful PCI. Although AL^4-6 and other backup-type catheters^7,8 have been used in this situation, these were not useful in the present case for selective cannulation and maintenance of coaxial position. The mother-child catheter technique, which uses several different inner catheters, has also been reported to be successful,^9-12 but this technique failed in the present case. Therefore, we employed an 8 Fr JL 3.5 guide catheter in the power position. Matchison et al reported that pushing the JL 3.5 to form a loop in the left coronary cusp made the tip of the guide catheter coaxial to the RCA origin.¹³ The principal theory explaining guide catheter support was advocated by Yuji Ikari.^14,15 With the patient-specific 3D model in the present study, we can explain why the JL 3.5 guide catheter in the power position yields stronger support (Figure 6). The anomalous RCA originated from the left sinus of Valsalva perpendicular to the LCA in an axial CT image. Conventional guide catheters, such as JL in the normal position, AL, and other backup-type catheters, could not become coaxial to the RCA ostium because they usually gain back-up support from the contralateral aortic wall. In contrast, the JL 3.5 guide catheter was able to become coaxial to the RCA ostium by forming a loop in the left sinus of Valsalva, and in this power position, it provided adequate support. 

Several studies have described the utility of preoperative planning using patient-specific 3D organ models.^16,17 3D printing technology, which has the potential to revolutionize medical model production and prototyping, is developing rapidly and becoming more affordable. To the best of our knowledge, the present paper is the first to demonstrate the utility of 3D printing for planning a difficult PCI. 

Study limitations. The 3D model employed in the present study has several limitations. First, it takes at least 1 week to make a 3D model from the patient’s DICOM data. Thus, the model cannot be used in emergent cases. Second, creating a patient-specific 3D model is still expensive. Third, the 3D printer cannot create a large model. The maximum build size is 40 x 40 x 20 cm. More accurate simulation will be possible if the 3D printer can create an entire aortocoronary system. 

Conclusion

The present case is a proof of concept that shows the possibility of creating patient-specific 3D models from routine CCTA data and their application in clinical practice. Further studies are expected to clarify whether the use of patient-specific 3D models facilitate decision making and increase success rates. 

Acknowledgments. We would like to express the utmost respect and gratitude to Professor Yuji Ikari for his previous works. He created the principal theory for analyzing guide catheter support.

References

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From the Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted August 22, 2014, provisional acceptance given September 18, 2014, final version accepted September 25, 2014.

Address for correspondence: Naritatsu Saito, Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. Email: naritatu@kuhp.kyoto-u.ac.jp