Chronic total occlusions - Current techniques and future directions

Clinical study on endovascular recanalization of non-acute symptomatic middle cerebral artery occlusion

Objective

Endovascular recanalization in patients with non-acute symptomatic middle cerebral artery occlusion remains clinically challenging. Here, we aimed to evaluate the feasibility and safety of endovascular recanalization for non-acute symptomatic middle cerebral artery occlusion and propose a new patient classification.

Methods

Between January 2019 and December 2021, 88 patients with non-acute symptomatic middle cerebral artery occlusion underwent prospective endovascular recanalization at our hospital. All patients were divided into three groups according to occlusion length, occlusion duration, occlusion nature, calcification of the occlusion site, and occlusion angulation. The indicators of each group were analyzed, including general baseline data, imaging data, surgical conditions, and follow-up results.

Results

Of the 88 patients, 73 were successfully recanalized and 15 were abandoned because the instruments either could not reach the distal true lumen of the occlusion or broke through the blood vessels. The overall technical success rate was 83.0% (73/88), and perioperative complications occurred in 15 patients. Preoperatively, all patients were divided into three risk groups: low, medium, and high. From the low- to high-risk groups, the recanalization rate gradually decreased (100.0, 91.7, and 16.7%, respectively, P = 0.020), the perioperative complication rate gradually increased (0, 13.9, and 83.3%, respectively, P < 0.001), the proportion of the modified Rankin scale scores >2 at 90 days increased (0, 11.7, and 50.0%, P < 0.001), and the restenosis/reocclusion rates in the 73 cases of successful recanalization increased (0, 16.1, and 100%, P = 0.012) during follow-up.

Conclusion

Endovascular recanalization may be feasible and safe in well-selected patients with non-acute symptomatic middle cerebral artery occlusion, especially in the low- and medium-risk groups.

Myocardial contrast echocardiographic diagnosis and follow-up of interventricular septal hematoma after retrograde intervention for a chronic total occlusion of a right coronary artery: a case report

BACKGROUND

Chronic total occlusion percutaneous coronary interventions (CTO-PCI) can be highly complex and are associated with an increased risk of complications. Coronary perforation (CP) is one of the most feared complications of CTO-PCI. Awareness of the potential consequence, as well as meticulous attention to patient monitoring, can aid in rapid treatment if it happens. We present a unique case covering myocardial contrast echocardiography (MCE) characterization of interventricular septal hematoma secondary to CP associated with decompression of the hematoma into the left ventricle cavity and a favorable clinical outcome.

CASE DESCRIPTION

This is a case of a patient with no space-occupying effect in interventricular septum before CTO-PCI showed severe chest pain after PCI. Bedside echocardiography showed thickening of the interventricular septum with the anechoic area, and contrast-enhanced echocardiography suggested the presence of interventricular septal hematoma and coronary-ventricular fistula. It was considered that retrograde CTO-PCI led to CP, which developed into an interventricular septal hematoma. The hematoma obstructed the right ventricular outflow tract (RVOT) to a lesser amount; at the same time, the perforated coronary artery created a fistula with the left ventricle, resulting in perfusion damage and myocardial ischemia to some extent, although the patient's vital signs remained stable. Therefore, conservative treatment was carried out under close observation. The patient stayed stable. The hematoma was absorbed 7 days after the operation, and completely absorbed 1 month later.

CONCLUSIONS

Although most cases of myocardial hematoma caused by CP can be treated conservatively without causing acute hemodynamic damage, a myocardial hematoma can progress at any time. Closely monitoring the changes in patients' symptoms and vital signs; mastering the location of the perforated coronary artery, the size of the hematoma and the hemodynamic abnormalities can help clinicians quickly make further treatment plans. Echocardiography coupled with contrast-enhanced ultrasonography, which is non-invasive, safe, cost-effective, and bedside-operable may accurately indicate the location, size of the hematoma, whether there is a shunt, as well as observe the hemodynamic changes and myocardial perfusion in real-time.

Optimization Study of the Hemodynamics of Saline Flushing in Endoscopic Imaging of Chronic Total Occlusions (CTOs)

PURPOSE

In this study, in vitro experiments and computational fluid dynamic (CFD) simulations are used to expand the understand of the physics of saline flushing of a blocked artery to enable optical imaging. This process involves saline injection, mixing with blood, and advection of the mixture away from the region of interest to provide a clear optical path for imaging.

METHODS

CFD simulations are used as a rapid turn-around tool for the evolutionary design process of an endovascular catheter that combines imaging forward-viewing element with saline flushing lumens.

RESULTS

A novel design and control technique is developed that provides the method to regulate the pressure in a blocked artery during saline flushing, so only small deviations from physiological pressure values are exerted on the damaged artery wall at any time, minimizing risk of rupture. In vitro experiments demonstrate the optical clearing process in phantoms simulating chronic total occlusions (CTOs) in coronary arteries with an opaque blood surrogate being removed by saline flushing. With the CFD compared by the experiments, parametric analyses of artery diameter and curvature, and flushing lumen diameter size were conducted to understand their impact on flushing times and pressures. Different plaque morphologies were studied to explore the feasibility of saline flushing in different CTO conditions.

CONCLUSIONS

A new catheter design is demonstrated to safely and effectively produce saline flushing, leading to a clear optical imaging field, and an improved technique is outlined that overcomes some practical challenges and limitations commonly encountered in angioscopy.

Rotational Atherectomy-Assisted Crossing of a Complex Right Coronary Artery Lesion Using the Retrograde Approach

Chronic total occlusion lesions present a major challenge for the interventional cardiologist. In this case, we report the successful use of rotational atherectomy to facilitate retrograde percutaneous coronary intervention of a complex totally occluded right coronary artery after modification of the proximal cap of the lesion to enable placement of the RotaWire in the vessel architecture.

How to perform a percutaneous coronary intervention, when no conventional arterial access site is available: A case report

Coronary artery disease is one of the leading causes of mortality in the world. The presence of concomitant peripheral artery disease increases the risks of cardiovascular events along with limiting the arterial access for coronary intervention. Invasive management of such cases includes either alternate site access or combined peripheral and coronary revascularization. We hereby report a patient of the infrarenal abdominal aorta and bilateral subclavian arterial occlusion, who presented with acute coronary syndrome. To perform the percutaneous coronary intervention, we first performed the endovascular stenting of occluded aortoiliac disease, followed by stenting of the right coronary artery. We had discussed the limitation of arterial access to perform PCI in such a situation.

Comparison of ante-versus retrograde access for the endovascular treatment of long and calcified, de novo femoropopliteal occlusive lesions

To compare antegrade versus retrograde recanalization, in terms of procedural time, radiation and contrast agent exposure, number and total length of implanted stents and procedural complications, in long and calcified, de novo femoropopliteal occlusions. We performed retrospective matching of prospectively acquired data by lesion length, occlusion length and lesion calcification by the peripheral arterial calcium scoring system (PACSS) score in patients who were referred for endovascular treatment due to symptomatic peripheral artery disease (PAD). Forty-two consecutive patients with antegrade and 23 patients with retrograde after failed antegrade recanalization were identified (mean lesion length = 32.1 ± 6.9 cm; mean occlusion length = 24.6 ± 7.7 cm; PACSS score = 3.25 ± 0.91). 23% of the patients had intermittent claudication, whereas 77% exhibited critical limb ischemia (CLI). Patients who underwent retrograde versus antegrade recanalization required a significantly lower number of stents (0.9 ± 1.0 versus 1.8 ± 1.4, p = 0.01) and a lower total stent length (6.8 ± 8.5 cm versus 11.7 ± 9.9 cm, p < 0.05) in the interest of more extensive coverage of the lesions using drug coated balloons (DCB) (28.5 ± 12.0 cm versus 18.2 ± 16.0 cm, p = 0.01). No re-entry device was required with the retrograde versus 9 of 42 (21%) with the antegrade recanalization group (p = 0.02). The rate of complications due to retrograde puncture was low (one patient with hematoma and one with distal pseudoaneurysm, both managed conservatively). In long and calcified femoropopliteal occlusions, the retrograde approach is associated with a lower number of re-entry devices and stents and with more extensive lesion coverage with DCB, in the interest of costs and possibly long-term patency.German Clinical Trials Register: DRKS00015277.

Parallel Guidewire for Catheter Stabilization in Interventional Radiology: The Anchoring Wire Technique

This technical note describes the parallel guidewire method: the anchoring technique as a strategy to ease difficult catheterization in various endovascular interventions. Sixteen patients were included in 2017 in whom this technique was used. The type of intervention, the nature of the target and anchored vessels and possible complications on the anchored vessel were reported. This study included thirteen various embolization cases and four visceral vessels angioplasties cases. The success of catheterization by using this technique was achieved in all cases, without complication on the anchored vessels.

Endovascular recanalization for symptomatic subacute and chronic intracranial large artery occlusion of the anterior circulation: initial experience and technical considerations

PURPOSE

This study aimed to report the clinical findings and initial clinical experience of endovascular recanalization for symptomatic subacute/chronic intracranial large artery occlusion (ILAO) of the anterior circulation.

METHODS

From October 2015 to December 2017, 13 patients with symptomatic subacute/chronic ILAO of the anterior circulation were enrolled in this study and underwent endovascular recanalization. We collected the initial procedural results, including the rate of successful recanalization and periprocedural complications, and data pertaining to angiographic and clinical follow-up.

RESULTS

Recanalization was successful in 11 of 13 patients (84.6%). Intraoperative complications occurred in four cases, including symptomatic distal embolism in three cases; one of which was simultaneously complicated with artery dissection. Intracerebral hemorrhage occurred in one case. Eleven patients underwent angiographic follow-up, and 12 patients underwent clinical follow-up. The results of the angiography follow-up (mean 6 ± 3.29 months) showed that in-stent restenosis occurred in one of the 11 successfully recanalized patients. However, the artery was occluded again in the patient who achieved thrombolysis in cerebral infarction (TICI) grade of 2a after treatment. Clinical follow-up (mean 5.8 ± 2.25 months) showed no recurrence of transient ischemic attack (TIA) or stroke in ten successfully recanalized cases. However, the patient who developed in-stent stenosis suffered TIA.

CONCLUSIONS

Endovascular recanalization for symptomatic subacute/chronic ILAO of anterior circulation is feasible, relatively safe, and efficacious in highly selected cases, improving patients' symptoms in the short-term. However, further larger scale pilot studies are needed to determine the efficacy and long-term outcome associated with this treatment.

A Novel Strategy for Chronic Total Occlusion of the Stumpless Ostial Left Anterior Descending Artery

BACKGROUND Despite improvements in percutaneous coronary intervention (PCI) devices and operator expertise, coronary chronic total occlusion (CTO) poses a management dilemma for interventional cardiologists. Occasionally, in CTO lesions and in bifurcation lesions with severe curvature and stenosis, wires cannot be introduced into the main artery, although wiring into the side branch is possible. We herein report a case of stumpless ostial left anterior descending artery (LAD) CTO that was successfully treated with a novel strategy. CASE REPORT A 64-year-old female with symptoms of heart failure was admitted to our hospital. Coronary angiography showed CTO of the stumpless ostial LAD. The patient had invisible and continuous collaterals; therefore, we used the antegrade approach for CTO access. However, the wire could be guided only in the direction of the diagonal branch due to a severe angulation at the CTO exit site, despite successful wire crossing into the CTO lesion. We attempted intravascular ultrasound-guided direct wire entry technique to obtain additional information about the occlusion cap location and to assist in negotiating the wire into the true lumen. The guidewire (Conquest pro) could cross the lesion after several approaches and successfully advance the device over the wire through the occluded segment after the modified See-saw wiring technique was employed. CONCLUSIONS This method appears to be a promising novel strategy for difficult and complex lesions when performing CTO revascularization.

Rock-Hard Chronic Thrombotic Occlusion and Its Management in Endovascular Interventions

Endovascular recanalization for patient with peripheral arterial disease and the end of its spectrum critical limb ischemia (CLI) has become a preferred method of revascularization due to advancement of techniques and equipment, allowing reduction of limb amputations while maintaining a minimally invasive approach compared to surgical approaches. Interventionalists have undertaken a progressively increasing complexity of diseased vessels in the hopes of providing inline unobstructed flow through occlusions for patients with claudication as well as direct flow to a nonhealing wound in patients with CLI. One of the major roadblocks encountered in lower extremity recanalization procedures is managing severely calcified chronic thrombotic occlusions which decrease luminal revascularization, ultimately increasing use of adjunctive interventions such as subintimal tracking, reentry device utilization, and stent placement. Understanding the histopathology and classification of lower extremity calcifications, imaging findings, and escalation of equipment use provides a thorough background in dealing with these specific cases.

A Magnetically Controlled Soft Microrobot Steering a Guidewire in a Three-Dimensional Phantom Vascular Network

Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional in vitro tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.

Coronary chronic total occlusion intervention: A pathophysiological perspective

Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is the last frontier in coronary intervention. PCI of CTO carries multiple advantages, such as significant improvement in symptoms, improvement in abnormal wall motion and left ventricular function and, possibly, increased long-term survival. As of today the procedural success is markedly improved because of technical innovations and is limited to highly experienced operators. To enhance the overall success rate from a worldwide perspective, a thorough understanding of its pathophysiology is critical to further development of newer techniques and technologies. In this review, the author outlines in-depth the evidence that underpins our understanding of CTO pathophysiology and its insight into CTO intervention that incorporates various steps and techniques to cross the lesion.

Epicardial collateral channel for retrograded recanalization of chronic total occlusion percutaneous coronary intervention: Predictors of failure and procedural outcome

OBJECTIVES

This study set out to identify significant lesion features of chronic total occlusion (CTO) that predict successful retrograde recanalization via epicardial collateral channels (CCs).

BACKGROUND

Epicardial CCs remain essential in retrograde percutaneous coronary intervention (PCI) of CTO. However, the unpredictability of success and occurrence of complications limit the application of epicardial CCs for retrograde PCI technique for CTO.

METHODS

103 retro-recanalization cases were analyzed using epicardial CCs with successful recanalization as an end point. Clinical and angiography data were collected.

RESULTS

The total success rate was 76.3%. Independent predictors associated with technical success included CCs tortuosity, side branch at CCs tortuosity, inadequate CCs Size and inadequate CCs exit location. Assigning a score of one for each variable, four levels of difficulty were obtained and formed the EPI-CTO score (Epicardial CTO). This score had significant predictive value for the likelihood of successful recanalization (AUC: 0.94, 95%CI: 0.89-0.98). Coronary and CCs perforation occurred in 6 and 10 cases respectively. Four cases including two coronary and two CCs perforations had tamponade that needed pericardiocentesis.

CONCLUSIONS

Using epicardial CCs for retrograde approach of CTO PCI is effective. Complication rate was acceptable. We found four independent predictors relative to procedure success.

Contemporary Evidence, Treatment Strategies, and Indications for Chronic Total Occlusion-Percutaneous Coronary Intervention

Chronic total occlusions (CTOs) are detected incidentally in ˜20% of patients undergoing coronary angiography and are often associated with significant morbidity and mortality. CTOs can manifest with worsening symptoms, reduced left ventricular function, and increased incidence of ventricular arrhythmias. Despite this, according to USA, Italian, and Japanese national registry data, only ~5–22% of CTO lesions are treated by percutaneous coronary intervention (PCI). CTO-PCI is a particularly challenging technique for this subset of lesions and has traditionally been associated with increased risks and complications compared to conventional PCI. However, increased experience, the development of novel techniques, and dedicated equipment have revolutionised CTO-PCI. USA, Italian, and Japanese registry data have shown success rates of between 85% and 90%, with diminishing complication rates when performed by experienced operators. Moreover, observational studies have suggested that there are significant benefits of using CTO-PCI, including fewer symptoms, improved quality of life, reduced need for coronary artery bypass surgery, and reduction in ischaemic burden and mortality. In addition, when there is demonstrable ischaemia and viable myocardium in the CTO territory, there is further potential prognostic benefit from complete revascularisation. However, there has so far been a relative lack of randomised trial data to support the routine use of CTO-PCI. This paper reviews the current evidence surrounding this subject and discusses the arguments for and against CTO-PCI. It includes an exploration of the interventionalist’s ‘toolbox’ and the techniques used in CTO-PCI, including a section on ‘tips and tricks’ for the most challenging cases. Finally, there is a discussion on the future of CTO-PCI including promising ongoing clinical trials and novel equipment that may improve outcomes and help to establish a more widespread adoption of CTO-PCI.

Transcatheter pulmonary valve perforation using chronic total occlusion wire in pulmonary atresia with intact ventricular septum

Background:

Perforation of pulmonary valve using radiofrequency ablation in pulmonary atresia with intact ventricular septum (PA IVS) is a treatment of choice. However, significant cost of the equipment limits its utility, especially in the developing economies.

Objective:

To assess the feasibility, safety, and efficacy of perforation of pulmonary valve using chronic total occlusion (CTO) wires in patients with PA IVS as an alternative to radiofrequency ablation.

Methods:

This is a single-center, nonrandomized, retrospective study conducted during June 2008 to September 2015. Twenty-four patients with PA IVS were selected for the procedure during the study period. The median age and weight of the study population were 8. days and 2.65 kg, respectively. Four patients were excluded after right ventricular angiogram as they showed right ventricular-dependent coronary circulation. The pulmonary valve perforation was attempted using various types of CTO wires based on the tip load with variable penetrating characteristics.

Results:

The procedure was successful in 16 of twenty patients using CTO wires: Shinobi in nine, Miracle in four, CROSS-IT in two, and Conquest Pro in one. Two patients had perforation of right ventricular outflow tract (RVOT). Pericardiocentesis was required in one patient to relieve cardiac tamponade. Later, the same patient underwent successful hybrid pulmonary valvotomy. The other patient underwent ductus arteriosus (DA) stenting. Balloon atrial septostomy was needed in three cases with systemic venous congestion. Desaturation was persistent in five cases necessitating DA or RVOT stenting to augment pulmonary blood flow. There were two early and two late deaths. The mean follow-up was 22.66 ± 16 months. Three patients underwent one and half ventricle repair and one Blalock–Taussig shunt during follow-up.

Conclusion:

Perforation of the pulmonary valve can be done successfully using CTO wires in selected cases of pulmonary atresia with intact ventricular septum.

Initial clinical experience of CrossBoss catheter for in-stent chronic total occlusion lesions: A case report

BACKGROUND

The CrossBoss coronary chronic total occlusion (CTO) crossing catheter has been demonstrated to have greatly improved the success rate of crossing CTO lesions, but there are no published data on its application for in-stent CTO lesions.

METHODS

In the current study, we retrospectively reviewed the clinical data of 8 patients with in-stent CTO lesions that were managed with the CrossBoss catheter and herein we report the efficacy and safety of the CrossBoss crossing and re-entry system for this clinically challenging condition.

RESULTS

The CrossBoss catheter was used for 8 patients with in-stent CTO lesions, which resulted in success in 6 cases and failure in 2 cases, with a 75% success rate. Of the 6 patients with successful treatment, 5 cases had the occlusive lesions crossed with the CrossBoss catheter through a proximal lumen-to-distal lumen approach, whereas the remaining case had his occlusive lesions penetrated by the CrossBoss catheter and the guidewire. Two cases failed in treatment as the CrossBoss catheter could not cross the occlusive lesions. The 6 cases with successful treatment included 3 cases with occlusive lesions in the left anterior descending artery, 1 case with occlusive lesions in the obtuse marginal branches, and 2 cases with occlusive lesions in the right coronary artery, and the 2 cases with failure in treatment had their occlusive lesions in the right coronary artery. In addition, patients with a higher Japan chronic total occlusion score were found to have a lower success rate of crossing the occlusive lesions. None of the patients developed complications.

CONCLUSION

Our study demonstrates that the CrossBoss catheter has a high success rate and is safe for in-stent CTOs and can be recommended for this rather clinically challenging condition.