Comprehensive appraisal of cardiac motion artefact in optical coherence tomography.

BACKGROUND: The relation between cardiac motion artefact (CMA) in optical coherence tomography (OCT) and the phases of cardiac cycle is unclear. METHODS: Optical coherence tomography pullbacks containing metallic stents were co-registered with angiography and retrospectively analyzed. The beginning of three phases, namely ejection, rapid-inflow and diastasis, was identified in angiography. Rotation, shortening, elongation and repetition were qualitatively labelled as CMA artefacts. Platforms with coaxial longitudinal connectors (ML8 and Magmaris) entered a quantitative sub-study, consisting of measuring the length of their connector at the beginning of each phase. RESULTS: A total of 261 stents (127 patients) were analyzed, including 105 stents for quantitative sub-study. CMA was detected in 61 (23.4%) stents: rotation in 6 (2.3%), shortening in 50 (19.2%), elongation in 51 (19.5%) and repetition in 12 (4.6%). Shortening was always observed during ejection phase, while elongation and repetition were always observed during rapid-inflow. Rotation occurred in both ejection and rapid-inflow phases, while no artefact was reported during diastasis. Longitudinal connectors measured in early ejection phase and in early rapid-inflow phase were shorter and longer, respectively, than those measured in diastasis, irrespective of the presence of CMA in the qualitative assessment. CONCLUSIONS: Cardiac motion artefact is prevalent in OCT studies, but shortening and elongation of vascular structures occur during early ejection and during early rapid-inflow, respectively, to a greater or lesser extent in all cases. Diastasis is free of CMA and hence the period in which longitudinal measurements can be more accurately quantified.

Subintimal shift as mechanism for side-branch occlusion in percutaneous treatment of chronic total occlusions with bifurcation lesions.

BACKGROUND: The aim of this study was to describe the mechanism of subintimal shift (SIS), standardise diagnostic criteria and sensitise the interventional community to this phenomenon. The treatment of chronic total occlusions (CTO) by means of percutaneous coronary intervention (PCI) is complicated by bifurcation lesions involved in the CTO segment or adjacent to it. Extraplaque expansion of intracoronary devices during CTO PCI may extend the dissection plane over the bifurcation with the consequential side or main branch compression by an intimo-medial flap. This phenomenon is hereby described for the first time and named subintimal shift. METHODS: Experienced CTO operators from 3 international high volume centers for CTO PCI retrospectively searched their personal records for paradigmatic cases of SIS, summarising key features and proposing diagnostic criteria. RESULTS: The series comprised 7 demonstrative cases, illustrating SIS by intravascular imaging (2 cases) or indirect angiographic signs during CTO PCI (5 cases). Five cases were triggered by stent expansion, 1 by balloon inflation and 1 case was aborted after angiographic warning signs. In 4 cases, SIS resulted in total occlusion of a branch, refractory to ballooning whenever attempted. Four cases required bailout intervention and in 2 cases the branch was left occluded, resulting in a rise of cardiac markers. CONCLUSIONS: Subintimal shift is a noteworthy complication in CTO bifurcations, potentially resulting in occlusion of the relevant side or even the main branch. Intracoronary imaging prior to stenting is recommended to understand the tissue planes. Some counterintuitive peculiarities of this phenomenon, like its refractoriness to ballooning, must be known by CTO operators for its efficient resolution.

Identification of the type of stent with three-dimensional optical coherence tomography: the SPQR study.

BACKGROUND: The ability of optical coherence tomography (OCT) to identify specific types of stent has never been systematically studied. AIMS: The aim of this study was to test the accuracy of OCT imaging to identify patterns of stent platform and subsequently identify the type of stent implanted. METHODS: Consecutive patients from six international centres were retrospectively screened, searching for OCT studies with metallic stents or scaffolds. The sample was analysed by two blinded operators, applying a dedicated protocol in four steps to identify the type of stent: 1) 3D and automatic strut detection (ASD), 2) 3D tissue view, 3) longitudinal view with ASD, 4) mode "stent only" and ASD. RESULTS: A series of 212 patients underwent OCT in the study centres, finding 294 metallic stents or scaffolds in 146 patients. The protocol correctly identified 285 stents (96.9%, kappa 0.965), with excellent interobserver agreement (kappa 0.988). The performance tended to be better in recently implanted stents (kappa 0.993) than in stents implanted ≥3 months before (kappa 0.915), and in pullback speed 18 mm/s as compared with 36 mm/s (kappa 0.969 vs 0.940, respectively). CONCLUSIONS: The type of stent platform can be accurately identified in OCT by trained analysts following a dedicated protocol, combining 3D-OCT, ASD and longitudinal view. This might be clinically helpful in scenarios of device failure and for the quantification of apposition. The blinding of analysts in OCT studies should be revisited.

Importance of platelets and fibrinogen in neutrophil-endothelial cell interactions in septic shock.

OBJECTIVE: To examine the role of platelets, fibrin, and adhesion molecules in mediating neutrophil-endothelial cell interactions in septic shock. DESIGN: Controlled experiments using phase contrast microscopy to examine neutrophil, platelet, and endothelial cell interactions in flowing cell suspensions under simulated physiologic conditions. SETTING: University research laboratory. PATIENTS: Adult patients with septic shock and normal volunteers. INTERVENTIONS: Microslides were coated with human umbilical vein endothelial cells. Neutrophils were removed from control subjects and patients in septic shock and were perfused over endothelial cells at rates representing a range of physiologic shear stresses. In an attempt to examine the effects of fibrin deposition on neutrophil-endothelial cell interactions, neutrophils, with and without platelets, were suspended in plasma and serum was removed from patients in septic shock. In addition, blocking monoclonal antibodies against the platelet receptor P-selectin and neutrophil receptor CD11b/CD18, and a platelet glycoprotein IIb/IIIa inhibitor, were incubated with cells suspended in plasma. Phase contrast video microscopy was used to count the number of neutrophils/mm adherent to endothelial cells during cessation of flow. Neutrophil rolling velocity was calculated as the time required for neutrophils to move across a 1-mm field (mm/sec). Leukoaggregation was defined as the number of neutrophils in aggregates (three or more nuclei) across a 1-mm field. MEASUREMENTS AND MAIN RESULTS: Normal neutrophils exposed to plasma from patients with septic shock demonstrated significant increases in aggregation and endothelial cell adherence with associated decreases in neutrophil rolling velocity. These changes were significantly enhanced in the presence of platelets and significantly attenuated in the presence of serum, which is fibrinogen depleted. Preincubation with antibodies to the surface receptors P-selectin, CD11b/CD18, and glycoprotein IIb/IIIa abrogated the changes in neutrophil aggregation, adhesion, and rolling velocity. CONCLUSIONS: These data suggest that platelets and fibrinogen play an important role in mediating neutrophil-endothelial cell adherence in septic shock.