Direct Percutaneous Left Ventricular Access and Port Closure Pre-Clinical Feasibility

ObjectivesThis study sought to evaluate feasibility of nonsurgical transthoracic catheter-based left ventricular (LV) access and closure.BackgroundImplanting large devices, such as mitral or aortic valve prostheses, into the heart requires surgical exposure and repair. Reliable percutaneous direct transthoracic LV access and closure would allow new nonsurgical therapeutic procedures.MethodsPercutaneous direct LV access was performed in 19 swine using real-time magnetic resonance imaging (MRI) and an “active” MRI needle antenna to deliver an 18-F introducer sheath. The LV access ports were closed percutaneously using a commercial ventricular septal defect occluder and an “active” MRI delivery cable for enhanced visibility. We used “permissive pericardial tamponade” (temporary fluid instillation to separate the 2 pericardial layers) to avoid pericardial entrapment by the epicardial disk. Techniques were developed in 8 animals, and 11 more were followed up to 3 months by MRI and histopathology.ResultsImaging guidance allowed 18-F sheath access and closure with appropriate positioning of the occluder inside the transmyocardial tunnel. Of the survival cohort, immediate hemostasis was achieved in 8 of 11 patients. Failure modes included pericardial entrapment by the epicardial occluder disk (n = 2) and a true-apex entry site that prevented hemostatic apposition of the endocardial disk (n = 1). Reactive pericardial effusion (192 ± 118 ml) accumulated 5 ± 1 days after the procedure, requiring 1-time drainage. At 3 months, LV function was preserved, and the device was endothelialized.ConclusionsDirect percutaneous LV access and closure is feasible using real-time MRI. A commercial occluder achieved hemostasis without evident deleterious effects on the LV. Having established the concept, further clinical development of this approach appears realistic

Whole shaft visibility and mechanical performance for active MR catheters using copper-nitinol braided polymer tubes

<p>Abstract</p> <p>Background</p> <p>Catheter visualization and tracking remains a challenge in interventional MR.</p> <p>Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency waves. We developed a new "active" catheter design for interventional MR with mechanical performance resembling braided X-ray devices. Our 75 cm long hybrid catheter shaft incorporates a wire lattice in a polymer matrix, and contains three distal loop coils in a flexible and torquable 7Fr device. We explored the impact of braid material designs on radiofrequency and mechanical performance.</p> <p>Results</p> <p>The incorporation of copper wire into in a superelastic nitinol braided loopless antenna allowed good visualization of the whole shaft (70 cm) <it>in vitro </it>and <it>in vivo </it>in swine during real-time MR with 1.5 T scanner. Additional distal tip coils enhanced tip visibility. Increasing the copper:nitinol ratio in braiding configurations improved flexibility at the expense of torquability. We found a 16-wire braid of 1:1 copper:nitinol to have the optimum balance of mechanical (trackability, flexibility, torquability) and antenna (signal attenuation) properties. With this configuration, the temperature increase remained less than 2°C during real-time MR within 10 cm horizontal from the isocenter. The design was conspicuous <it>in vitro </it>and <it>in vivo</it>.</p> <p>Conclusion</p> <p>We have engineered a new loopless antenna configuration that imparts interventional MR catheters with satisfactory mechanical and imaging characteristics. This compact loopless antenna design can be generalized to visualize the whole shaft of any general-purpose polymer catheter to perform safe interventional procedures.</p

Defining levels of care in cardiogenic shock

BackgroundExpert opinion and professional society statements have called for multi-tier care systems for the management of cardiogenic shock (CS). However, little is known about how to pragmatically define centers with different levels of care (LOC) for CS.MethodsEleven of 23 hospitals within our healthcare system sharing a common electronic health record were classified as different LOC according to their highest mechanical circulatory support (MCS) capabilities: Level 1 (L-1)—durable left ventricular assist device, Level 1A (L-1A)—extracorporeal membrane oxygenation, Level 2 (L-2)—intra-aortic balloon pump and percutaneous ventricular assist device; and Level 3 (L-3)—no MCS. All adult patients treated for CS (International Classification of Diseases, ICD-10 code R57.0) between 2016 and 2022 were included. Etiologies of CS were identified using associated diagnostic codes. Management strategies and outcomes across LOC were compared.ResultsHigher LOC centers had higher volumes: L-1 (n = 1): 2,831 patients, L-1A (n = 4): 3,452, L-2 (n = 1): 340, and L-3 (n = 5): 780. Emergency room admissions were more common in lower LOC (96% at L-3 vs. 46% L-1; p &lt; 0.001), while hospital transfers were predominant at higher LOC (40% at L-1 vs. 2.7% at L-3; p &lt; 0.001). Men comprised 61% of the cohort. Patients were younger in the higher LOC [69 (60–78) years at L-1 vs. 77 (67–85) years at L-3; p &lt; 0.001]. Patients with acute myocardial infarction (AMI)-CS and acute heart failure (AHF)-CS were concentrated in higher LOC centers while other etiologies of CS were more common in L-2 and L-3 (p &lt; 0.001). Cardiac arrest on admission was more prevalent in lower LOC centers (L-1: 2.8% vs. L-3: 12.1%; p &lt; 0.001). Patients with AMI-CS received more percutaneous coronary intervention in lower LOC (51% L-2 vs. 29% L-1; p &lt; 0.01) but more coronary arterial bypass graft surgery at higher LOC (L-1: 42% vs. L-1A: 23%; p &lt; 0.001). MCS use was consistent across levels for AMI-CS but was more frequent in higher LOC for AHF-CS patients (L-1: 28% vs. L-2: 10%; p &lt; 0.001). Despite increasing in-hospital mortality with decreasing LOC, no significant difference was seen after multivariable adjustment.ConclusionThis is the first report describing a pragmatic classification of LOC for CS which, based on MCS capabilities, can discriminate between centers with distinct demographics, practice patterns, and outcomes. This classification may serve as the basis for future research and the creation of CS systems of care

Towards mri-guided cardiovascular interventions

Imaging guidance may allow minimally invasive alternatives to open surgical exposure and help reduce procedure risk and morbidity. The inherent vascular and soft-tissue contrast of MRI make it an appealing imaging modality to guide cardiovascular interventional procedures. Advances in real-time MRI have made MRI-guided procedures a realistic possibility. The MR environment, however, introduces additional challenges to the development of compatible, conspicuous and safe devices. The overall goal of this work was to enable selected MRI-guided cardiovascular interventional procedures with clearly visible MR devices. In the first part of this work, we developed actively visualized devices for three distinct MRI-guided interventional procedures and techniques to assess their signal performance. We then investigated factors influencing complex device safety in the MR environment and evaluated a technique to better determine and monitor potential device heating. This input contributed to the development of a system to further improve device safety with continual device monitoring and dynamic scanner feedback control. In the final part of this work, we demonstrated the utility of MRI guidance and actively visualized devices to enable traditional and complex cardiovascular access. Together these provide important elements to bring MRI-guided cardiovascular interventional procedures closer to clinical implementation.PhDCommittee Chair: Yoganathan, Ajit P; Committee Member: Lederman, Robert J; Committee Member: McVeigh, Elliot R; Committee Member: Oshinski, John N; Committee Member: Taylor, W Rober

Problem of the subjects' integration in the teatchers' training programmes containing two specialities

The article analyzes the syllabus on chemistry and mode of life culture specialty and opportunities for integration; it also attempts to reveal approach of pupils, students and lecturers to the content of specialty and their compatibility. Analysis of technology and chemistry and general education syllabus and opinion of pupils, students and lecturers and the opinion of class XII pupils about the application of chemical knowledge shows that both the chemistry and technology subjects are integral. It is thus appropriate to develop the bachelor syllabus on chemistry and mode of life culture specialty, thus partially assuring employment for teachers and development of competence for technology subject teachers. According to our records, class XII pupils have more information about chemistry than I year students of mode of life culture specialty. Therefore, during the admission of students to this specialty, it is necessary to consider the grade in chemistry in certificate. Mode of life culture specialty students indicate that, in order to absorb knowledge related to nutrition, housing, clothing and care well, they lack knowledge of chemistry subject. Students studying chemistry have more basic knowledge about chemistry, but they do not know how to put this knowledge into practice. This once again demonstrates the need for compatibility of two specialties