Percutaneous Coronary Intervention for Chronic Total Occlusion in a Patient with Situs Inversus: Challenges and Technical Considerations

Situs inversus is a rare condition that makes interventional procedures more challenging. We present a case of situs inversus associated with right coronary artery occlusion that was first documented on coronary computed tomography angiography. The procedure required multiple catheter exchanges and the use of a guide-extension catheter, ultimately resulting in successful stent implantation. Chronic total occlusion percutaneous coronary intervention in situs inversus requires special considerations due to the reversed coronary anatomy. Standard interventional techniques may not always be effective, requiring adjustments in catheter and wire selection, fluoroscopic views, and support strategies. A stepwise approach, incorporating appropriate catheter support and thorough lesion preparation, is key to achieving successful outcomes.

Situs inversus is an uncommon condition in which the organs develop in a mirror-image arrangement. Although it is typically asymptomatic, it can make procedures such as coronary interventions more difficult because the usual anatomic landmarks are reversed. These challenges become even greater when treating a chronic total occlusion (CTO), which is already one of the most complex scenarios in percutaneous coronary intervention (PCI).

Case Presentation

A 63-year-old male patient with a history of hypertension and situs inversus presented with a several-month history of exertional chest pain relieved by rest. The exercise stress test was clinically positive. The patient underwent coronary computed tomography angiography (CCTA), which confirmed situs inversus and revealed moderate stenosis in the mid-left anterior descending artery (LAD) as well as occlusion of the mid right coronary artery (RCA; Fig. 1, A and B). Based on CCTA-derived Japan (J)-CTO scoring, the lesion was classified as having intermediate complexity (J-CTO score of 2) due to the presence of calcification, the absence of a blunt stump, and a lesion length < 20 mm. The CT images demonstrated a reverse attenuation gradient sign, characterized by a progressive increase in attenuation beyond the occlusion, from 215 to 442 Hounsfield units. This finding suggests the presence of a chronic occlusion with collateral circulation. Coronary angiography was performed through right femoral arterial access. The left coronary artery was selectively injected using a Judkins Left 3.5 catheter. Mild atherosclerotic lesions were observed in the LAD and the left circumflex (LCx) arteries. A diagnostic Judkins Right (JR) 4.0 6 French catheter (Merit Medical Systems, South Jordan, UT) was used to intubate the right coronary artery, and the angiogram confirmed mid-RCA occlusion with partial filling of the distal vessel (Fig. 1C). A decision was made to proceed with CCTA-guided PCI of the RCA lesion. Initial attempts with a JR 4, Amplatz Left (AL) 1.0 (Merit Medical Systems, South Jordan, UT), and Multipurpose (MP) (Merit Medical Systems, South Jordan, UT) guiding catheters were complicated by multiple instances of catheter kinking due to difficulty in selectively intubating the right coronary ostium. Ultimately, repeated attempts with a JR 4.0 catheter succeeded, allowing passage of a Pilot 50 (Abbott Vascular, Santa Clara, CA) coronary guidewire across the lesion. A guide-extension catheter (Guideliner V3 catheter) (Teleflex Incorporated, Wayne, PA) was used to improve support. Balloons of 2.0 mm and 1.5 mm failed to cross the lesion, but a 0.85-mm balloon was successfully advanced. A stepwise approach with progressive balloon upsizing achieved good pre-stenting vessel preparation. A 2.75 x 38 mm drug-eluting stent was placed, followed by optimization with a 3.0-mm noncompliant balloon (Fig. 1D). The patient was prescribed dual antiplatelet therapy for at least 6 months, along with optimization of cardiovascular risk factors.

Figure 1.

(A) Coronary computed tomography angiography confirming Dextrocardia and showing the origin of the left coronary artery (red arrow: left main coronary artery), dividing into left anterior descending and left circumflex artery. (B) Coronary computed tomography angiography showing the origin of the right coronary artery, followed by chronic total occlusion (CTO; arrow). The CTO does not have a blunt stump, and is < 20 mm in length. (C) Coronary angiography (antero-posterior view) showing the origin of the RCA and the site of the CTO (arrow). (D) Coronary angiography (antero-posterior view) showing the final result after drug-eluting stent implantation.

Discussion

To our knowledge, this case is the first such reported of a CTO PCI patient with situs inversus, guided by both CCTA and conventional angiography. Situs inversus alone does not increase the risk of heart diseases, but it can complicate diagnosis and therapeutic interventions.¹ Both radial and femoral artery accesses can be used, although the femoral access is often preferred to improve support.² The left coronary artery arises from the right sinus of Valsalva, and the right coronary artery arises from the left sinus. Fluoroscopy angles and angiographic projections should therefore be reversed to accommodate the mirror-image coronary anatomy (Fig. 2). To intubate the left main artery, apical or right anterior oblique (RAO) views should be used, and cannulation of the RCA can be performed using RAO views.³ Standard catheters to engage the RCA can be used, including JR or AL/Amplatz Right catheters, but other type of catheters (eg, MP) might be needed. The left coronary artery can be engaged with Judkins Left catheters, but it may require a smaller curve (0.5 less) to compensate for the mirrored anatomy. AL catheters can be used for anteriorly deviated ostia. XB-EBU (Extra Backup) (Cordis, Santa Clara, CA) catheters also can be useful in challenging cases. Other alternatives include the Terumo Optitorque Tiger catheter (Terumo Medical Corporation, Somerset, NJ) (radial access) and the MP.⁴ To engage the RCA, the catheter should be pointed toward the right side of the screen, using an anticlockwise gentle torque and slight withdrawal techniques. For left coronary artery engagement, the catheter should be pointed toward the left side of the screen, and anticlockwise or clockwise torque can be applied depending on the movement of the catheter. To facilitate visualization of the coronary arteries, the double inversion technique can be used, which requires pressing the horizontal sweep reversal button on the machine to move the heart from the right side to the left side of the chest, and then applying a horizontal left-right inversion while maintaining the same cranial and caudal angulations (Fig. 2). In CTOs, the mirrored anatomy and the potential tortuosity of the RCA increase the challenges when manipulating guidewires. Here, the anterograde approach was used as a first-line strategy, but success can be limited in the presence of heavy calcifications or an ambiguous proximal cap. These challenges can be anticipated by performing CCTA to guide procedural planning. In such cases, a retrograde approach using collaterals can be used. To cross the lesion, tapered and hydrophilic guidewires such as the Fielder XT (ASAHI INTECC Co., Ltd., Aichi, Japan) or Pilot 50 can be used; however, these are not stiff wires but rather low tip-load wires designed for initial CTO crossing. Microcatheters also enhance wire support and control.⁵ The use of contra-lateral angiography also is valuable to confirm the position of the guidewire in the true lumen. In the current case, a guide-extension catheter was very helpful to improve pushability and facilitate device delivery across the heavily calcified lesion. After crossing of the lesion, a stepwise approach with progressive balloon upsizing was critical to achieving success. The CTO procedure was relatively straightforward once adequate guide support was achieved using a guide-extension catheter. Although the exact timing of the RCA occlusion is unknown, no clinical history of a recent myocardial infarction was present, and angiography showed features consistent with collateral bridging, suggesting that the occlusion was chronic (ie, more than 3 months).

Figure 2.

Double-inversion technique: right–left image inversion plus left anterior oblique ↔ right anterior oblique (LAO↔RAO) angulation reversal to reproduce standard coronary views in situs inversus. AP, anteroposterior.

Another key element for success here was ensuring strong and stable guide support. Because coronary takeoff is reversed and catheter behaviour differs in situs inversus, even seemingly straightforward lesions may become difficult to engage or deliver equipment through. Our case highlights the importance of selecting a guide catheter that offers good stability from the outset, as well as the utility of a guide-extension catheter when additional support is needed. In fact, an upfront guide-extension catheter strategy may make wire crossing and balloon delivery much easier in similar situations.

Although intravascular imaging (intravascular ultrasound or optical coherence tomography) was not performed here, its usefulness in complex lesions—including CTOs—is well established. Imaging likely would have helped characterize plaque morphology, assess calcium burden, and optimize stent expansion. In cases with atypical or reversed anatomy, incorporating intravascular ultrasound or optical coherence tomography can be particularly valuable and should be strongly considered.

Previous reports have described the technical challenges associated with situs inversus during angiography and/or PCI. Our study extends these reports by demonstrating the potential role of CCTA, particularly in CTO PCI. Here, CCTA provided a detailed anatomic roadmap before the intervention that helped anticipate and navigate the procedural challenges. In a patient with known situs inversus, CCTA can be extremely valuable before proceeding with invasive angiography. First, it may help avoid an unnecessary and potentially difficult diagnostic angiogram if no significant coronary disease is found. Second, when atherosclerotic disease is present, CCTA gives a clear view of coronary artery origin, course, dominance, and potential challenges, which helps the operator in anticipating difficulties and planning the procedure more effectively. This approach becomes even more important in CTO interventions. Information on vessel trajectory, stump morphology, calcium distribution, and collateral pathways can significantly influence the procedural approach. In our case, CCTA allowed us to confirm the reversed anatomy, evaluate the CTO lesion characteristics (including the J-CTO score), and plan the procedure. Overall, this process contributed to a smoother and more efficient PCI with reduced fluoroscopy time and contrast use. CCTA also can provide valuable insights on collateral circulation, thereby helping in selecting the best procedural strategy.⁶

Conclusion

This case underscores the importance of flexibility and adaptability when performing PCI in patients with situs inversus, particularly in CTO cases. Adjustments in catheter manipulation and fluoroscopy angles to address the reversed anatomy were used. Strategies such as use of a guide-extension catheter to enhance support, and a stepwise approach with progressive balloon upsizing were key to procedural success. Our case also highlights the valuable role of CCTA in planning and guiding these complex procedures.

Novel Teaching Points.

• •PCI in patients with situs inversus requires flexibility and adaptation to the reversed coronary anatomy.
• •Fluoroscopic angles and catheter manipulation techniques must be adjusted to achieve proper engagement and support.
• •Guide-extension catheters can provide essential support for device delivery in challenging CTO cases.
• •Stepwise lesion preparation with small-profile balloons facilitates safe and effective stent implantation.
• •CCTA offers valuable pre-procedural insights for strategy planning in complex cases.