Carina: A major determinant in the pathophysiology and treatment of coronary bifurcation lesions

Over the last decade, several in vivo and computational investigations have significantly advanced our understanding of the pathophysiology of coronary bifurcations, contributing to the enhancement of their percutaneous revascularization. The carina of the coronary bifurcations plays a substantial role in generating their main hemodynamic features, including distinctive flow patterns with secondary flows and specific shear stress patterns. These factors play a pivotal role in determining the susceptibility, development, and progression of atherosclerosis. The underlying pathophysiological mechanisms of atherosclerosis in coronary bifurcations are complex and multifactorial. Understanding these mechanisms is fundamental to comprehending lesions at the bifurcation level and informing future treatment strategies. This review aims to present the currently available data regarding the pathophysiological and prognostic role of the carina in coronary bifurcations, offering an interpretation of these findings from the perspective of interventional cardiologists, providing valuable insights for their clinical practice.

Clinical effectiveness and radial artery remodeling assessment via very-high-frequency ultrasound/ultra biomicroscopy after applying slender 7Fr sheath for transradial approach in left main bifurcation disease

OBJECTIVE

To explore the clinical effect and radial remodeling of transradial slender 7 Fr sheath for left main bifurcation disease (LM bifurcation).

METHODS

From January 2018 to September 2019, 236 patients with LM bifurcation undergoing transradial percutaneous coronary intervention (PCI) from two heart centers were divided into slender 7 Fr sheath group (n = 127) and 6 Fr sheath group (n = 109). Quantitative coronary angiography (QCA) and very high-frequency ultrasound/ultra biomicroscopy (VHFUBM) were used to assess the clinical effect and radial remodeling of transradial sheath.

RESULTS

Slender 7 Fr sheath group had a higher preoperative distal bifurcation angle (67.271 ± 22.886) than 6 Fr group (55.831 ± 20.245) (p < .05). Post-PCI QCA results showed significant differences in minimum lumen diameter at proximal left anterior descending artery (LAD) and left circumflex artery (LCX) between two groups (p < .05). There were no significant differences in target vessel myocardial infarction, target vessel revascularization, death and major adverse cardiocerebrovascular events (MACCE) at 30-day and 1-year follow-up between two groups (p>.05). No significant differences were observed in radial artery diameter (RAD), intimal-medial thickness (IMT) and radial artery injury at 24-h and 90-day follow-up between two groups.

CONCLUSION

With larger main and side branch diameter, larger angle of bifurcation and higher SYNTAX score, transradial slender 7 Fr sheath obtained similar clinical effects as 6 Fr sheath without increasing the occurrence of adverse events. Similar follow-up RAD, IMT and radial artery injury were observed. Therefore, slender 7 Fr sheath has safety and feasibility in applying to transradial LM-Bifurcation PCI.

State of the art: coronary angiography

In the early days of coronary angiography, the precise quantification of luminal narrowing was challenging. The introduction of balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]) by Andreas Grüntzig in 1977 was perhaps the greatest incentive to the development of quantitative coronary angiography (QCA). QCA has played a crucial role in evaluating interventional techniques and assessing the results of new technologies. With the advent of drug-eluting stents (DES), QCA metrics such as late lumen loss and diameter stenosis (restenosis) proved to be instrumental in assessing new technologies. Refinements in QCA with the advent of dedicated bifurcation analysis and three-dimensional (3D) QCA have broadened the application of QCA. Beyond angiographic metrics, new developments in the field of QCA have introduced the functional component in the assessment of coronary lesions. Angiography-derived fractional flow reserve (FFR) may be a good tool for diagnosing ischaemia-producing lesions in patients with non-complex coronary artery disease. Furthermore, the incremental functional information can be used to expand the traditional late lumen loss (LLL) and restenosis concepts.

Bench testing and coronary artery bifurcations: a consensus document from the European Bifurcation Club

This is a consensus document from the European Bifurcation Club concerning bench testing in coronary artery bifurcations. It is intended to provide guidelines for bench assessment of stents and other strategies in coronary bifurcation treatment where the United States Food and Drug Administration (FDA) or International Organization for Standardization (ISO) guidelines are limited or absent. These recommendations provide guidelines rather than a step-by-step manual. We provide data on the anatomy of bifurcations and elastic response of coronary arteries to aid model construction. We discuss testing apparatus, bench testing endpoints and bifurcation nomenclature.

Everolimus-eluting bioresorbable vascular scaffolds implanted in coronary bifurcation lesions: Impact of polymeric wide struts on side-branch impairment

BACKGROUND

Limited data are available on bioresorbable vascular scaffolds (BVS) performance in bifurcations lesions and on the impact of BVS wider struts on side-branch impairment.

METHODS

Patients with at least one coronary bifurcation lesion involving a side-branch ≥2mm in diameter and treated with at least one BVS were examined. Procedural and angiographic data were collected and a dedicated methodology for off-line quantitative coronary angiography (QCA) in bifurcation was applied (eleven-segment model), to assess side-branch impairment occurring any time during the procedure. Two- and three-dimensional QCA were used. Optical coherence tomography (OCT) analysis was performed in a subgroup of patients and long-term clinical outcomes reported.

RESULTS

A total of 102 patients with 107 lesions, were evaluated. Device- and procedural-successes were 99.1% and 94.3%, respectively. Side-branch impairment occurring any time during the procedure was reported in 13 bifurcations (12.1%) and at the end of the procedure in 6.5%. Side-branch minimal lumen diameter (Pre: 1.45±0.41mm vs Final: 1.48±0.42mm, p=0.587) %diameter-stenosis (Pre: 26.93±16.89% vs Final: 27.80±15.57%, p=0.904) and minimal lumen area (Pre: 1.97±0.89mm(2) vs Final: 2.17±1.09mm(2), p=0.334), were not significantly affected by BVS implantation. Mean malapposed struts at the bifurcation polygon-of-confluence were 0.63±1.11.

CONCLUSIONS

The results of the present investigation suggest feasibility and relative safety of BVS implantation in coronary bifurcations. BVS wide struts have a low impact on side-branch impairment when considering bifurcations with side-branch diameter≥2mm.

Patient-specific coronary stenoses can be modeled using a combination of OCT and flow velocities to accurately predict hyperemic pressure gradients

Computational fluid dynamics (CFD) is increasingly being developed for the diagnostics of arterial diseases. Imaging methods such as computed tomography (CT) and angiography are commonly used. However, these have limited spatial resolution and are subject to movement artifact. This study developed a new approach to generate CFD models by combining high-fidelity, patient-specific coronary anatomy models derived from optical coherence tomography (OCT) imaging with patient-specific pressure and velocity phasic data. Additionally, we used a new technique which does not require the catheter to be used to determine the centerline of the vessel. The CFD data were then compared with invasively measured pressure and velocity. Angiography imaging data of 21 vessels collected from 19 patients were fused with OCT visualizations of the same vessels using an algorithm that produces reconstructions inheriting the in-plane (10 μm) and longitudinal (0.2 mm) resolution of OCT. Proximal pressure and distal velocity waveforms ensemble averaged from invasively measured data were used as inlet and outlet boundary conditions, respectively, in CFD simulations. The resulting distal pressure waveform was compared against the measured waveform to test the model. The results followed the shape of the measured waveforms closely (cross-correlation coefficient = 0.898 ± 0.005, ), indicating realistic modeling of flow resistance, the mean of differences between measured and simulated results was -3. 5 mmHg, standard deviation of differences (SDD) = 8.2 mmHg over the cycle and -9.8 mmHg, SDD = 16.4 mmHg at peak flow. Models incorporating phasic velocity in patient-specific models of coronary anatomy derived from high-resolution OCT images show a good correlation with the measured pressure waveforms in all cases, indicating that the model results may be an accurate representation of the measured flow conditions.

Acute procedural and six-month clinical outcome in patients treated with a dedicated bifurcation stent for left main stem disease: the TRYTON LM multicentre registry

AIMS

Tryton side branch (SB) reverse culotte stenting has been employed for the treatment of left main (LM) stem bifurcations in patients at high risk for bypass surgery. The aim of this study was to assess acute angiographic results and six-month clinical outcome after implantation of the Tryton stent in the LM.

METHODS AND RESULTS

We studied 52 consecutive patients with LM disease treated in nine European centres. Angiographic and clinical data analysis was performed centrally. Fifty-one of 52 patients (age 68±11 yrs, 75% male, 42% unstable angina, SYNTAX score 20±8) were successfully treated with the Tryton stent. Medina class was 1,1,1 in 33 (63%), 1,0,1 in 7 (13%), 1,1,0 in 3 (6%), 0,1,1 in 8 (4%) and 0,0,1 in 1 (2%). The Tryton stent on a stepped balloon (diameter 3.5-2.5 mm) was used in 41/51 (80%) of cases. The mean main vessel stent diameter was 3.4±0.4 mm with an everolimus-eluting stent employed in 30/51 (59%) of cases. Final kissing balloon dilatation was performed in 48/51 (94%). Acute gain was 1.52±0.86 mm in the LM and 0.92±0.47 mm in the SB. The angiographic success rate was 100%; the procedural success rate reached 94%. Periprocedural MI occurred in three patients. At six-month follow-up, the TLR rate was 12%, MI 10% and cardiac death 2%. The hierarchical MACE rate at six months was 22%. No cases of definite stent thrombosis occurred.

CONCLUSIONS

The use of the Tryton stent for treatment of LM bifurcation disease in combination with a conventional drug-eluting stent is feasible and achieves an optimal angiographic result. Safety of the procedure and six-month outcome are acceptable in this high-risk lesion PCI. Further safety and efficacy studies with long-term outcome assessment of this strategy are warranted.

An image-based guidewire navigation method for robot-assisted intravascular interventions

This paper aims at using a newly developed robotic system to automatically deliver guidewires or catheters to the target site on percutaneous coronary interventions (PCIs) or electrophysiology interventions. An autonomous delivery strategy using electromagnetic tracking technology is introduced and phantom experiments are performed to validate this strategy. In order to advance the guidewire into the planned branch, the strategy classifies this branch selection problem into three cases according to the width of the vessels and employs an image-based algorithm for the first and second cases. Another image-based algorithm specifically designed for the third case is also presented.