Ex vivo imaging of chronic total occlusions using forward-looking optical coherence tomography

The CathCam: A Novel Angioscopic Solution for Endovascular Interventions

Peripheral arterial diseases are commonly managed with endovascular procedures, which often face limitations in device control and visualization under X-ray fluoroscopy guidance. In response, we developed the CathCam, an angioscope integrated into an expandable cable-driven parallel mechanism to enhance real-time visualization, precise device positioning and catheter support for successful plaque crossing. The primary objective of this study was to assess and compare the performance of the novel CathCam with respect to conventional catheters and the CathPilot (i.e., CathCam without the angioscope), for applications in crossing chronic total occlusions (CTO). We first assessed the system in 3D-printed phantom models, followed by an ex vivo evaluation with CTO samples from a patient's superficial femoral artery. We measured and compared success rates, crossing times, and fluoroscopy times in both experiments. The CathCam demonstrated a 100% success rate in phantom experiments and a 75% success rate in ex vivo experiments with CTO samples, compared to conventional catheters, with 35% and 25% success rates, respectively. The average crossing times for the CathCam and the conventional catheter were 31 s and 502 s for the phantom experiments and 210 s and 511 s for the actual CTO lesions. The Cathcam also showed to be a reliable endovascular imaging approach in an in vivo experiment. Compared to conventional catheters, the CathCam significantly increased the success rate and reduced crossing and fluoroscopy times in both phantom and ex vivo setups. CathCam can potentially improve clinical outcomes for minimally invasive endovascular interventions by offering high-resolution real-time imaging alongside accurate device control.

Advantages and prospects of optical coherence tomography in interventional therapy of coronary heart disease (Review)

Coronary heart disease is the leading cause of mortality among all diseases globally. Percutaneous coronary intervention (PCI) is a key method for the treatment of coronary heart disease. Optical coherence tomography (OCT) is an optical diagnostic technology with a resolution of up to 10 µm, which is able to accurately assess the composition of the coronary arterial wall and determine the characteristics of atherosclerotic lesions. It is also highly consistent with pathological examinations, optimizing the effect of stent implantation and evaluation of the long-term effectiveness and safety of the stent, which has irreplaceable value in the field of precision and optimization of coronary intervention. The innovative OCT technology may help provide more comprehensive clinical research evidence. The application of OCT in clinical and basic research of coronary atherosclerosis, selection of treatment strategies for acute coronary syndromes, optimization of interventional treatment efficacy, evaluation of novel stents, intimal stent coverage and selection of dual antiplatelet drugs has become more widely used, affecting the current coronary interventional treatment strategies to a certain extent. The aim of the present review was to discuss the role of OCT in evaluating preoperative plaque characteristics, guiding PCI and evaluating the effects of postoperative stents or drug treatments.

Femoropopliteal Artery Stent Thrombosis: Report From the Excellence in Peripheral Artery Disease Registry

BACKGROUND

There are limited data on femoropopliteal artery stent thrombosis (ST), which is a serious adverse outcome of peripheral artery interventions.

METHODS AND RESULTS

Index procedures resulting in femoropopliteal ST were compared with stent procedures without subsequent ST in the Excellence in Peripheral Artery Disease registry. The study data had a total of 724 cases of stent procedures and 604 unique patients. Femoropopliteal ST occurred in 26 of 604 patients (4.3%) over a median follow-up of 6 months post procedure. ST was more likely to occur in men (96.3% versus 82.2%; P=0.026) and to have an initial intervention for chronic total occlusions (88.5% versus 64.0%; P=0.01). There was no significant difference in ST between drug-coated and bare-metal stents (4.4% versus 3.4%; P=0.55), but the rate of ST was significantly higher with self-expanding covered stent grafts compared with bare-metal stents (10.6% versus 3.4%; P=0.02). ST was significantly associated with an increased risk of 12-month major adverse limb events (hazard ratio, 4.99; 95% confidence interval, 2.31-10.77; P<0.001) compared with no ST. On multivariate analysis, treatment of chronic total occlusion lesions (odds ratio, 3.46; 95% confidence interval, 0.98-12.20; P=0.05) and in-stent restenosis lesions (odds ratio, 5.30; 95% confidence interval, 1.83-15.32; P=0.002) were independently associated with an increased risk of ST.

CONCLUSIONS

In a multicenter peripheral interventional registry, femoropopliteal ST occurred in 4.3% of patients who underwent stent procedures, and it was associated with treatment of chronic total occlusions and in-stent restenosis lesions, and had higher 12-month major adverse limb events.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01904851.

Optical coherence tomography for guiding wire into a side branch coronary artery with flush total occlusion

We report a case of flush occlusion, where a novel use of optical coherence tomography (OCT) helped in successful crossing and stenting of the lesion.

Spatial encoding using the nonlinear field perturbations from magnetic materials

PURPOSE

A proof-of-concept study was performed to assess the technical feasibility of using magnetic materials to generate spatial encoding fields.

THEORY AND METHODS

Spatially varying magnetic fields were generated by the placement of markers with different volume susceptibilities within the imaging volume. No linear gradients were used for spatial encoding during the signal acquisition. A signal-encoding model is described for reconstructing the images encoded with these field perturbations. Simulation and proof-of-concept experimental results are presented. Experiments were performed using field perturbations from a cylindrical marker as an example of the new encoding fields. Based on this experimental setup, annular rings were reconstructed from signals encoded with the new fields.

RESULTS

Simulation results were presented for different acquisition parameters. Proof-of-concept was supported by the correspondence of regions in an image reconstructed from experimental data compared to those in a conventional gradient-echo image. Experimental results showed that inclusions of dimensions 1.5 mm in size could be resolved with the experimental setup.

CONCLUSION

This study shows the technical feasibility of using magnetic markers to produce encoding fields. Magnetic materials will allow generating spatial encoding fields, which can be tailored to an imaging application with less complexity and at lower cost compared to the use of gradient inserts.

Collagenase Total Occlusion-1 (CTO-1) trial: a phase I, dose-escalation, safety study

BACKGROUND

Percutaneous interventions for chronic total occlusions have low success rates, primarily because of failure of guide wire crossing. Collagen-rich matrix constitutes the main barrier to chronic total occlusion crossing. In preclinical studies, local delivery of a bacterial collagenase formulation improved guide wire crossing. The Collagenase Total Occlusion-1 (CTO-1) Trial is a phase I, dose-escalation trial to assess the safety and efficacy of collagenase therapy to facilitate guide wire crossing in coronary artery chronic occlusions.

METHODS AND RESULTS

Twenty subjects with ≥1 previous failure of chronic total occlusion guide wire crossing were enrolled at 2 sites. Subjects were treated in 4 distinct cohorts of 5 patients, with escalation of collagenase dose in each cohort from 300 to 1200 μg. Collagenase was locally delivered into the occlusions with either an over-the-wire balloon system (n=8) or a fine-cross microcatheter (n=12) for a period of 30 minutes. Subjects were brought back to the catheterization laboratory for guide wire crossing and angioplasty the next day. Guide wire crossing was successfully achieved in 15 subjects (75%). A soft-tip guide wire (Whisper, Pilot-50, Fielder XT) was either the sole or predominant guide wire used in 75% of successful crossings. Non-ST-segment-elevation myocardial infarctions occurred in 3 patients as a result of side-branch ischemia during stenting. Computed tomographic angiography at 3 months showed no late complications and patent stents in successfully treated chronic total occlusion. Anginal improvement occurred with a reduction in Canadian Cardiovascular Society class from baseline to 3 months (2.5±0.6 versus 0.9±0.9; P<0.001).

CONCLUSION

Local delivery of collagenase into coronary chronic total occlusion is feasible and safe with encouraging guide wire crossing results in previously failed cases. Larger clinical trials are required to determine efficacy.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01271335.

Optical coherence tomography: fundamental principles, instrumental designs and biomedical applications

The advances made in the last two decades in interference technologies, optical instrumentation, catheter technology, optical detectors, speed of data acquisition and processing as well as light sources have facilitated the transformation of optical coherence tomography from an optical method used mainly in research laboratories into a valuable tool applied in various areas of medicine and health sciences. This review paper highlights the place occupied by optical coherence tomography in relation to other imaging methods that are used in medical and life science areas such as ophthalmology, cardiology, dentistry and gastrointestinal endoscopy. Together with the basic principles that lay behind the imaging method itself, this review provides a summary of the functional differences between time-domain, spectral-domain and full-field optical coherence tomography, a presentation of specific methods for processing the data acquired by these systems, an introduction to the noise sources that plague the detected signal and the progress made in optical coherence tomography catheter technology over the last decade.

Doppler optical coherence tomography for interventional cardiovascular guidance: in vivo feasibility and forward-viewing probe flow phantom demonstration

We demonstrate the potential of a forward-looking Doppler optical coherence tomography (OCT) probe for color flow imaging in several commonly seen narrowed artery morphologies. As a proof of concept, we present imaging results of a surgically exposed thrombotic occlusion model that was imaged superficially to demonstrate that Doppler OCT can identify flow within the recanalization channels of a blocked artery. We present Doppler OCT images in which the flow is nearly antiparallel to the imaging direction. These images are acquired using a flexible 2.2-mm-diam catheter that used electrostatic actuation to scan up to 30 deg ahead of the distal end. Doppler OCT images of physiologically relevant flow phantoms consisting of small channels and tapered entrance geometries are demonstrated.