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Tip detection-antegrade dissection and reentry using intravascular ultrasound in chronic total occlusion intervention: first human case report

Abstract Background It has been considered impossible to perform antegrade dissection and reentry (ADR) by simply puncturing with a guidewire using the intravascular ultrasound (IVUS) observation without the support of the Stingray system. Case summary A 78-year-old man suffered from effort angina pectoris due to a chronic total occlusion (CTO) lesion in the left circumflex coronary artery. A retry percutaneous coronary intervention for the CTO lesion was attempted at our hospital. The J-CTO score was 3. The first guidewire entered the subintimal space. We moved onto Stingray-ADR using the angiographic observation, but the guidewire could not be led into the true lumen. AnteOwl WR-IVUS (AO-IVUS) observation revealed a distal true lumen in which the inner lumen was maintained 5 mm beyond the CTO exit. We decided to perform the tip detection-ADR using the AO-IVUS observation. The tip detection method allowed the tip of the penetration wire to puncture the wall between the subintima and the true lumen in an exactly vertical direction, resulting in the successful creation of a reentry point. The CTO lesion was dilated with one drug-eluting stent, and normal antegrade blood flow was achieved. Discussion Since the tip detection method enables accurate punctures, it may allow for ADR by simply puncturing using a guidewire. Due to this method being performed using the IVUS observation, it is likely more reliable than Stingray-ADR using the angiographic observation.


Background
It has been considered impossible to perform antegrade dissection and reentry (ADR) by simply puncturing with a guidewire using the intravascular ultrasound (IVUS) observation without the support of the Stingray system.
Case summary A 78-year-old man suffered from effort angina pectoris due to a chronic total occlusion (CTO) lesion in the left circumflex coronary artery. A retry percutaneous coronary intervention for the CTO lesion was attempted at our hospital. The J-CTO score was 3. The first guidewire entered the subintimal space. We moved onto Stingray-ADR using the angiographic observation, but the guidewire could not be led into the true lumen. AnteOwl WR-IVUS (AO-IVUS) observation revealed a distal true lumen in which the inner lumen was maintained 5 mm beyond the CTO exit. We decided to perform the tip detection-ADR using the AO-IVUS observation. The tip detection method allowed the tip of the penetration wire to puncture the wall between the subintima and the true lumen in an exactly vertical direction, resulting in the successful creation of a reentry point. The CTO lesion was dilated with one drug-eluting stent, and normal antegrade blood flow was achieved.

Discussion
Since the tip detection method enables accurate punctures, it may allow for ADR by simply puncturing using a guidewire. Due to this method being performed using the IVUS observation, it is likely more reliable than Stingray-ADR using the angiographic observation. • To recognize that AnteOwl WR-intravascular ultrasound-based three-dimensional wiring using the tip detection method can allow reentry without a reentry device in chronic total occlusion (CTO) percutaneous coronary intervention.
• To control the CTO stiff guidewires accurately according to the tip detection method.

Introduction
In chronic total occlusion (CTO), percutaneous coronary intervention (PCI), antegrade dissection and reentry (ADR) using the Stingray system (Stingray-ADR; Boston Scientific, Natick, MA, USA) has been widely used, but it does not have a high level of accuracy because it is a procedure using the angiographic observation. 1 It has been considered impossible to perform ADR by simply puncturing with a guidewire using the intravascular ultrasound (IVUS) observation without the support of the Stingray system.
We developed AnteOwl WR-IVUS (AO-IVUS; Terumo Corp., Tokyo, Japan), which has a short tip and a pullback transducer system and devised a tip detection method to standardize IVUS-based three-dimensional (3D) wiring. 2,3 This method has been established to accurately advance guidewires inside the intraplaque in CTO lesions. However, while performing it, we first found that the tip detection method allows for ADR because the wall between the subintima and the true lumen can be punctured at the intended part in an exactly vertical direction using the IVUS observation. We named this method 'tip detection-ADR (TD-ADR)'.

Timeline Case summary
A 78-year-old Asian man with an old inferior myocardial infarction suffered from effort angina pectoris due to CTO lesions in the left circumflex coronary artery and left anterior descending coronary artery. His significant past medical history was dyslipidaemia. PCI was performed on the CTO lesion in the left circumflex coronary artery at another hospital ( Figure 1A). During antegrade wire escalation, a guidewire seemed to enter the subintimal space angiographically ( Figure 1B) and could not be passed through the CTO lesion.
The patient was admitted to our hospital 1 month later for a retry procedure for the CTO lesion. He was independently mobile, and had received optimal medical therapy consisting of antiplatelet medication. The physical examination revealed the following: blood pressure, 122/72 mmHg and heart rate, 57 bpm. There were no cardiac murmur and pulmonary rales. The electrocardiogram displayed abnormal Q-waves in lead II, II, aVF. Echocardiography showed inferior wall motion hypokinesis with an ejection fraction of 57% and no significant valvular heart disease. The blood test showed that creatinine level was 1.01 mg/dL (normal values 0.70-1.20 mg/dL), and N-terminal pro-brain natriuretic peptide level was 114.7 pg/dL (normal values , 125 pg/dL). A presumptive diagnosis of effort angina pectoris due to the CTO lesions was made by electrocardiogram and echocardiography which showed the viability of the anterior and posterior walls. We planned to perform only the antegrade approach because there were no interventional retrograde channels. The procedure was performed from the femoral approach with an 8-Fr guiding catheter. An XT-R wire (Asahi Intecc Co., Ltd., Aichi, Japan) supported by a Finecross microcatheter (Terumo Corp.) seemed to enter the subintimal space angiographically, which was confirmed by AO-IVUS (Figure 2A and B). Then, the AO-IVUS-based 3D wiring was performed ( Figure 2B), but the guidewire could not be advanced because of a huge calcified wall at the transition site. Although the true lumen beyond the CTO exit was not clearly visible angiographically, we moved onto Stingray-ADR using an angiographic observation ( Figure 2C). Using Confianza-20 g (Asahi Intecc) and XT-R wires, five attempts of the stick-and-swap technique were performed, but the guidewire could not be led into the true lumen under the angiographic observation ( Figure 2D).
IVUS observation revealed a distal true lumen in which the inner lumen was maintained 5 mm beyond the CTO exit ( Figure 3A). We decided to perform TD-ADR using the AO-IVUS observation. The Confianza-20 g supported by the Finecross was advanced at the site where we attempted reentry ( Figure 3E). The tip detection method allowed the tip of the Confianza-20 g to puncture the wall between the subintima and the true lumen in an exactly vertical direction (Figure 3B-E; Supplementary material online, Video S1), resulting in successful reentry ( Figure 3F). The CTO lesion was dilated with one drug-eluting stent, and normal antegrade blood flow was achieved ( Figure 2F). The patient was discharged on post-operative day 2.

Discussion
Various reentry techniques have already been reported, 1 and the standard strategy is the Stingray-ADR. But, there can be problems in visualizing the target because all of the techniques depend on angiographic images. Compared with them, TD-ADR enables the puncture to be at a more proximal part and allows a pinpoint puncture of the intended part in the vertical direction, because the target and the guidewire tip are clearly visible using the IVUS observation ( Figure 4). The global CTO algorithm has recently been reported ( Figure 5A), 4 but we hope that it will be changed to the following algorithm including the use of AO-IVUS ( Figure 5B). The procedural details are shown in Supplementary material online, Video S2. When the antegrade approach is continued after the failure of The patient was admitted to our hospital.

Day 2
The retry percutaneous coronary intervention for the chronic total occlusion in the left circumflex coronary artery was performed.    However, if it is difficult to insert an IVUS catheter, the angiographybased parallel wiring or Stingray-ADR will be selected ( Figure 5B).

Conclusion
AO-IVUS-based 3D wiring using the tip detection method has been established as a method for accurately advancing guidewires inside the intraplaque. However, it can also be utilized to intentionally create a reentry point because an exact vertical directional puncture can be achieved.