A review of the development of interventional devices for mitral valve repair with the implantation of artificial chords

Mitral regurgitation (MR) was the most common heart valve disease. Surgical repair with artificial chordal replacement had become one of the standard treatments for mitral regurgitation. Expanded polytetrafluoroethylene (ePTFE) was currently the most commonly used artificial chordae material due to its unique physicochemical and biocompatible properties. Interventional artificial chordal implantation techniques had emerged as an alternative treatment option for physicians and patients in treating mitral regurgitation. Using either a transapical or a transcatheter approach with interventional devices, a chordal replacement could be performed transcatheter in the beating heart without cardiopulmonary bypass, and the acute effect on the resolution of mitral regurgitation could be monitored in real-time by transesophageal echo imaging during the procedure. Despite the in vitro durability of the expanded polytetrafluoroethylene material, artificial chordal rupture occasionally occurred. In this article, we reviewed the development and therapeutic results of interventional devices for chordal implantation and discuss the possible clinical factors responsible for the rupture of the artificial chordal material.

Procedural Outcome Following Stent-Assisted Coiling for Wide-Necked Aneurysms Using Three Different Stent Models: A Single-Center Experience

Previous case series have described the safety and efficacy of different stent models for stent-assisted aneurysm coiling (SAC), but comparative analyses of procedural results are limited. This study investigates the procedural outcome and safety of three different stent models (Atlas™, LEO+™ (Baby) and Enterprise™) in the setting of elective SAC treated at a tertiary neuro-endovascular center. We retrospectively reviewed all consecutively treated patients that received endovascular SAC for intracranial aneurysms between 1 July 2013 and 31 March 2020, excluding all emergency angiographies for acute subarachnoid hemorrhage. The primary procedural outcome was the occlusion rate evaluated with the Raymond–Roy occlusion classification (RROC) assessed on digital subtraction angiography (DSA) at 6- and 12-month follow-up. Safety assessment included periprocedural adverse events (i.e., symptomatic ischemic complications, symptomatic intracerebral hemorrhage, iatrogenic perforation, dissection, or aneurysm rupture and in-stent thrombosis) and in-house mortality. Uni- and multivariable logistic regression analyses were performed to identify patient baseline and aneurysm characteristics that were associated with complete aneurysm obliteration at follow-up. A total of 156 patients undergoing endovascular treatment via SAC met the inclusion criteria. The median age was 62 years (IQR, 55–71), and 73.7% (115) of patients were female. At first follow-up (6-month) and last available follow-up (12 and 18 months), complete aneurysm occlusion was observed in 78.3% (90) and 76.9% (102) of patients, respectively. There were no differences regarding the occlusion rates stratified by stent model. Multivariable logistic analysis revealed increasing dome/neck ratio (adjusted odds ratio (aOR), 0.26.; 95% CI, 0.11–0.64; p = 0.003), increasing neck size (aOR, 0.70; 95% CI, 0.51–0.96; p = 0.027), and female sex (aOR, 4.37; 95% CI, 1.68–11.36; p = 0.002) as independently associated with treatment success. This study showed comparable rates of complete long-term aneurysm obliteration and safety following SAC for intracranial aneurysm with three different stent-models highlighting the procedural feasibility of this treatment strategy with currently available stent-models. Increased neck size and a higher dome/neck ratio were independent variables associated with less frequent complete aneurysm obliteration.

Combined Coronary Orbital Atherectomy and Intravascular Lithotripsy for the Treatment of Severely Calcified Coronary Stenoses: The First Case Series

OBJECTIVE

Severely calcified coronary stenoses remain a significant challenge during contemporary percutaneous coronary intervention (PCI), often requiring advanced therapies to circumvent suboptimal lesion preparation and major adverse cardiac events (MACEs). Recent reports suggest combined coronary atherectomy and intravascular lithotripsy (IVL) may achieve superior preparation of severely calcified coronary stenoses during PCI. We sought to evaluate the safety and utility of combined orbital atherectomy (OA) and IVL for the modification of coronary artery calcification (CAC) prior to drug-eluting stent (DES) implantation in PCI.

METHODS

We performed a retrospective review of all patients who underwent coronary OA and IVL within a single PCI procedure at our institution. The primary outcome was procedural success, defined as successful DES implantation with a residual percent diameter stenosis of <30% and Thrombolysis in Myocardial Infarction (TIMI) 3 flow following PCI without occurrence of in-hospital MACE (cardiac death, myocardial infarction, or target-vessel revascularization). MACE was additionally assessed at 30 days post intervention.

RESULTS

Eight patients underwent combined coronary OA and IVL within a single PCI procedure. The mean percent diameter stenosis prior to intervention was 80.5 ± 8.3%, with a mean calcific arc of 338 ± 42°. Procedural success was achieved in 7 of 8 cases (87.5%). Both in-hospital and 30-day MACE rates were 0%.

CONCLUSION

We report the safe and effective use of combined coronary OA and IVL for the preparation of severely calcified coronary stenoses during PCI. Through their distinct yet complementary mechanisms of action, the combined use of these therapies may achieve superior preparation of severely calcified coronary stenoses during PCI.

The Development of an ex vivo Flow System to Assess Acute Arterial Drug Retention of Cardiovascular Intravascular Devices

Purpose: The goal of this study was to develop an ex vivo system capable of rapidly evaluating arterial drug levels in living, isolated porcine carotid arteries.

Methods: A vascular bioreactor system was developed that housed a native porcine carotid artery under physiological flow conditions. The ex vivo bioreactor system was designed to quantify the acute drug transfer of catheter-based drug delivery devices into explanted carotid arteries. To evaluate our ex vivo system, a paclitaxel-coated balloon and a perfusion catheter device delivering liquid paclitaxel were utilized. At 1-h post-drug delivery, arteries were removed, and paclitaxel drug levels measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Parallel experiments were performed in a pig model to validate ex vivo measurements.

Results: LC-MS/MS analysis demonstrated arterial paclitaxel levels of the drug-coated balloon-treated arteries to be 48.49 ± 24.09 ng/mg and the perfusion catheter-treated arteries to be 25.42 ± 9.74 ng/mg at 1 h in the ex vivo system. Similar results were measured in vivo, as arterial paclitaxel concentrations were measured at 59.23 ± 41.27 ng/mg for the drug-coated balloon-treated arteries and 23.43 ± 20.23 ng/mg for the perfusion catheter-treated arteries. Overall, no significant differences were observed between paclitaxel measurements of arteries treated ex vivo vs. in vivo.

Conclusion: This system represents the first validated ex vivo pulsatile system to determine pharmacokinetics in a native blood vessel. This work provides proof-of-concept of a quick, inexpensive, preclinical tool to study acute drug tissue concentration kinetics of drug-releasing interventional vascular devices.

Fluid-based augmentation of magnetic resonance visualization of interventional devices

PURPOSE

To evaluate the transient artifact augmentation of microtubes in magnetic resonance imaging by fluid injection.

METHODS

Twenty-one fluorinated ethylene propylene catheters (inner diameter 760 μm) were filled with three different contrast media at various concentrations (Ferucarbotran, Resovist®, Bayer Schering Pharma; Manganese dichloride, MnCl2, Sigma-Aldrich; Gadobutrol, Gadovist®, Bayer Schering Pharma). Artifact appearance was determined in an ex vivo phantom at 1.5 T using three different sequences: T1-weighted three-dimensional volume interpolated breath-hold examination, T2-weighted turbo spin echo, and T1-weighted fast low angle shot. Catheter angulation to the main magnetic field (B0) was varied. Influence of parameters on artifact diameters was assessed with a multiple linear regression similar to an analysis of variance.

RESULTS

Artifact diameter was significantly influenced by the contrast agent (p < 0.001), concentration of the contrast agent (p < 0.001), angulation of the phantom to B0 with the largest artifact at 90° (p < 0.001), and encoding direction with a larger diameter in phase encoding direction (PED, p < 0.001). Mean artifact diameters at 90° angulation to B0 in PED were 18.5 ± 5.4 mm in 0.5 mmol/ml Ferucarbotran, 8.7 ± 2.5 mm in 1 mmol/ml Gadobutrol, and 11.6 ± 4.6 mm in 5 mmol/ml MnCl2 .

CONCLUSIONS

Fluid-based contrast agents might be applied to interventional devices and thus temporarily augment the artifact ensuring both visibility and safe navigation.

Dynamic Characterisation of Fibre-Optic Temperature Sensors for Physiological Monitoring

Fast, miniature temperature sensors are required for various biomedical applications. Fibre-optics are particularly suited to minimally invasive procedures, and many types of fibre-optic temperature sensors have been demonstrated. In applications where rapidly varying temperatures are present, a fast and well-known response time is important; however, in many cases, the dynamic behaviour of the sensor is not well-known. In this article, we investigate the dynamic response of a polymer-based interferometric temperature sensor, using both an experimental technique employing optical heating with a pulsed laser, and a computational heat transfer model based on the finite element method. Our results show that the sensor has a time constant on the order of milliseconds and a -6 dB bandwidth of up to 178 Hz, indicating its suitability for applications such as flow measurement by thermal techniques, photothermal spectroscopy, and monitoring of thermal treatments.

Use of institutional criteria for transcatheter device closure of Fontan fenestration - Midterm outcomes

Background:

There are no established criteria to decide suitability for Fontan fenestration closure. Our institution has the following criteria: an unobstructed Fontan pathway with no significant decompressing venovenous collaterals, baseline Fontan pressure ≤15 mmHg, baseline cardiac index ≥2 L/min/m², and a decrease in cardiac index ≤20% with test occlusion of the fenestration.

Objective:

The objective of the study was to review midterm outcomes following device closure of Fontan fenestration using institutional criteria.

Materials and Methods:

A retrospective review was performed of patients who underwent catheterization with prior fenestrated Fontan procedure between May 2005 and January 2015. Patients were classified as those who underwent successful closure (A), had closure deferred due to failure to meet criteria (B), or were not referred for closure (C).

Results:

There were 42 patients in Group A, 10 in Group B, and 150 in Group C. The mean Fontan pressure increased from 13.1 ± 2.1 to 14.5 ± 2.1mmHg in Group A and 14.6 ± 1.5 to 15.7 ± 2.2 mmHg in Group B (P = not significant). With test occlusion, cardiac index fell by 18.12% ± 15.68% in Group A and 33.75% ± 14.98% in Group B (P = 0.019). At a median of 46 month follow-up, oxygen saturation increased significantly from 85.15% ± 6.29% at baseline to 94.6% ± 4.43% (P < 0.001) in Group A but with no statistically significant difference in the rates of plastic bronchitis, protein-losing enteropathy, stroke, or heart transplantation between the three groups.

Conclusions:

Using institutional criteria, transcatheter device closure of Fontan fenestration was followed by significant increase in oxygen saturations and no statistically significant difference in morbidity or mortality between closure and nonclosure groups.

Percutaneous closure of patent ductus arteriosus with the Nit-Occlud® patent ductus arteriosus device in 268 consecutive cases

Background

The pfm Nit-Occlud^® patent ductus arteriosus (PDA) device is well established for interventional closure of PDA. However, there are still limited data concerning its efficacy and follow-up in larger patient groups.

Aims

This study aimed to evaluate the safety and efficacy of the Nit-Occlud^® PDA device, implanted both through transpulmonary and transaortic approach, in a large cohort.

Methods

From July 2008 to December 2015, 268 consecutive patients were admitted for transcatheter closure of a PDA and were treated with the Nit-Occlud^® coil. Clinical, echocardiographic, and angiographic data were evaluated.

Results

The median age was 5.2 years (range, 5 months to 62 years), and the median weight was 19.3 kg (range: 5.5-97 kg). Ten (3.7%) patients had weight <10 kg. The most common ductus types treated were Krichenko Type E and A (44.0% and 33.2%, respectively). Twelve (4.5%) patients were treated for residual shunting after surgical PDA closure. The median diameter at the narrowest point was 1.5 mm (range: 0.4-4 mm), the median size of the ampulla was 5 mm (range: 1-15 mm), and the median length was 9 mm (range: 2-25 mm). Device implantation could be successfully achieved in all cases. Closure rates documented immediately after the procedure, at 3-10 days, 1 month, and 6 months after intervention were 62%, 95.1%, 97.8%, and 98.5%, respectively. With the exception of one minor thromboembolic event, there were no procedure-related complications.

Conclusion

Closure of PDA with various anatomic variations and sizes can be performed effectively and safely using the Nit-Occlud^® coil.

Positive-contrast susceptibility imaging based on first-order primal-dual optimization

PURPOSE

To achieve faster reconstruction and better imaging quality of positive-contrast MRI based on the susceptibility mapping by incorporating a primal-dual (PD) formulation.

METHODS

The susceptibility-based positive contrast MR technique was applied to estimate arbitrary magnetic susceptibility distributions of the metallic devices using a kernel deconvolution algorithm with a regularized ℓ 1 minimization. The regularized positive-contrast inversion problem and its PD formulation were derived. The visualization of the positive contrast and convergence behavior of the PD algorithm were compared with those of the nonlinear conjugate gradient algorithm, fast iterative soft-thresholding algorithm, and alternating direction method of multipliers. These methods were tested and validated on computer simulations and phantom experiments.

RESULTS

The PD approach could provide a faster reconstruction time compared with other methods. Experimental results showed that the PD algorithm could achieve comparable or even better visualization and accuracy of the metallic interventional devices in positive-contrast imaging with different SNRs and orientations to the B₀ field.

CONCLUSION

A susceptibility-based positive-contrast imaging technique by PD algorithm was proposed. The PD approach has more superior performance than other algorithms in terms of reconstruction time and accuracy for imaging the metallic interventional devices.

Access and closure management of large bore femoral arterial access

Femoral and radial artery access continue to be the standard of care for percutaneous coronary interventions. Cardiac catheterization has progressed to encompass a wide range of diagnostic and interventional procedures including coronary, peripheral, endovascular, and structural heart disease interventions. Despite advanced technology to make these procedures safe, bleeding, and vascular complications continue to be a substantial source of morbidity, especially in patients undergoing large-bore access procedures. New variations of percutaneous devices have reduced complications associated with these procedures. However, safe vascular access with effective hemostasis requires special techniques which have not been well described in the literature. Large-bore femoral artery access is feasible, safe, and associated with low complication rates when a protocol is implemented. Wayne State University, Detroit Medical Center Heart Hospital is a tertiary care, high-volume center for endovascular, structural heart and complex high risk indicated procedures with more 150 procedures involving mechanical circulatory support (MCS) devices per year. In this manuscript, we describe our approach to femoral artery large-bore sheath insertion and management. Our protocol includes proper identification of the puncture site, device selection, insertion, assessment of limb perfusion while on prolong MCS support, and hemostasis techniques after sheath removal.

Successful percutaneous coil embolization of a severely tortuous coronary artery fistula using the mother-child-grandchild technique via a GuideLiner catheter

Coronary artery fistula is an uncommon congenital disease that requires invasive treatment for symptomatic patients. Although percutaneous intervention has become the popular treatment option, surgical treatment is preferred for severely tortuous coronary artery fistulas. We report a case of an extremely tortuous coronary artery fistula successfully treated with the support of the GuideLiner catheter and the mother-grandchild technique.

Percutaneous closure of an aortopulmonary window using Amplatzer Duct Occluder II: Additional Sizes: the first reported case

To date, there are no reported cases of the Amplatzer Duct Occluder II: Additional Sizes' use in percutaneous closure of an aortopulmonary window. We report a case of percutaneous closure of an aortopulmonary window in a 4.5-month-old, 6 kg child. Owing to the patient's low weight, high risk of damage to the pulmonary valve, as well as the possibility of aortic and pulmonary artery obstruction, classic implants were deemed unsuitable and a decision was made to use the Amplatzer Duct Occluder II: Additional Sizes. The implant performed very well - the soft waist filled the aortopulmonary connection and both retention discs were properly shaped and pressed against vessel walls. Echocardiogram performed 12 hours after the procedure confirmed a correct occluder position. Low-profile retention discs had no impact on pulmonary valve function, despite the defect's proximity to the valve. No obstruction of the aortic or pulmonary artery lumen was noted. The Amplatzer Duct Occluder II: Additional Size implant is a safe and useful device for percutaneous closure of an aortopulmonary window in a carefully selected group of patients.

Interventional multispectral photoacoustic imaging with a clinical ultrasound probe for discriminating nerves and tendons: an ex vivo pilot study

Accurate and efficient identification of nerves is an essential component of peripheral nerve blocks. While ultrasound (US) imaging is increasingly used as a guidance modality, it often provides insufficient contrast for identifying nerves from surrounding tissues such as tendons. Electrical nerve stimulators can be used in conjunction with US imaging for discriminating nerves from surrounding tissues, but they are insufficient to reliably prevent neural punctures, so that alternative methods are highly desirable. In this study, an interventional multispectral photoacoustic (PA) imaging system was used to directly compare the signal amplitudes and spectra acquired from nerves and tendons ex vivo, for the first time. The results indicate that the system can provide significantly higher image contrast for discriminating nerves and tendons than that provided by US imaging. As such, photoacoustic imaging could be valuable as an adjunct to US for guiding peripheral nerve blocks.

Central iliac arteriovenous anastomosis for hypertension: targeting mechanical aspects of the circulation

Raised blood pressure is the leading attributable risk factor for global morbidity and mortality. Real world data demonstrates that half of treated patients are at elevated cardiovascular risk because of inadequately controlled BP. In addition to pharmacotherapy, certain interventional strategies to reduce blood pressure and cardiovascular risk in hypertension can be considered according to international guidelines. One of the newer technologies entering this field is a proprietary arteriovenous coupler device that forms a fixed flow arteriovenous conduit in the central vasculature. In this review, we examine the development of and rationale for the creation of a central arteriovenous anastomosis in patients with hypertension and review the proposed mechanisms by which it may ameliorate hypertension. We critically review the clinical trial evidence base to date and postulate on future therapeutic directions.

Percutaneous closure of patent ductus arteriosus in children using amplatzer duct occluder II: relationship between PDA type and risk of device protrusion into the descending aorta

OBJECTIVES

To compare the efficacy and safety of Amplatzer Duct Occluder II (ADOII) among the various patent ductus arteriosus (PDA) types, and to assess the association between development of aortic obstruction and the PDA type in terms of measurable parameters as the device angulation and distance of upper end protrusion into the aortic lumen.

METHODS

Retrospective cohort study involving 50 consecutive subjects who underwent ADO II device closure of PDA.

RESULTS

The median age and weight at intervention were 13 months (5.5 months to 18 years) and 11 (6-67) kg respectively. The median smallest ductal diameter by angiography was 3.2 (1.9-5.4) mm. Thirty two patients had type A PDA, 5 had type C, 5 had type D, and 8 had type E. Residual shunt was seen in only 1 patient who had a tubular PDA and resolved within 2 months of the procedure. No device embolization or pulmonary side protrusion were noted. There was a 16% aortic protrusion rate. The median distance of protrusion of the upper end of the device into the aortic lumen was 3.1 (0-9) mm and the median angle formed between the aortic end of the device and the PDA take-off was 10.4 (0-80.6) degrees. These latter parameters of aortic obstruction were significantly higher in the non-conical PDA group as compared to the conical PDA. Nevertheless, there was no significant coarctation due to aortic retention disc protrusion.

CONCLUSION

Device closure of PDA using the ADO II is a safe procedure for chosen types of PDA. We demonstrated a novel technique for objective assessment of device protrusion into the descending aorta based on measurable parameters. ADOII device closure of non-conical PDAs warrants closer follow ups.

Double Ring Array Catheter for In Vivo Real-Time 3D Ultrasound

We developed new forward-viewing matrix transducers consisting of double ring arrays of 118 total PZT elements integrated into catheters used to deploy medical interventional devices. Our goal is 3D ultrasound guidance of medical device implantation to reduce x-ray fluoroscopy exposure. The double ring arrays were fabricated on inner and outer custom polyimide flexible circuits with inter-element spacing of 0.20 mm and then wrapped around an 11 French (Fr) catheter to produce a 15 Fr catheter (outer diameter [O.D.]). We used a braided cabling technology to connect the elements to the Volumetrics Medical Imaging (VMI) real-time 3D ultrasound scanner. Transducer performance yielded an average -6 dB fractional bandwidth of 49% ± 11% centered at 4.4 MHz for 118 elements. Real-time 3D cardiac scans of the in vivo pig model yielded good image quality including en face views of the tricuspid valve and real-time 3D guidance of an endo-myocardial biopsy catheter introduced into the left ventricle.

Safety measurements for heating of instruments for cardiovascular interventions in magnetic particle imaging (MPI) - first experiences

Magnetic particle imaging (MPI) has emerged as a new imaging method with the potential of delivering images of high spatial and temporal resolutions and free of ionizing radiation. Recent studies demonstrated the feasibility of differentiation between signal-generating and non-signal-generating devices in Magnetic Particle Spectroscopy (MPS) and visualization of commercially available catheters and guide-wires in MPI itself. Thus, MPI seems to be a promising imaging tool for cardiovascular interventions. Several commercially available catheters and guide-wires were tested in this study regarding heating. Heating behavior was correlated to the spectra generated by the devices and measured by the MPI. The results indicate that each instrument should be tested separately due to the wide spectrum of measured temperature changes of signal-generating instruments, which is up to 85°C in contrast to non-signal-generating devices. Development of higher temperatures seems to be a limitation for the use of these devices in cardiovascular interventions.

Fast track occlusion of aorta with atrial septal defect sizing balloon

We describe the case of a 57-year-old woman referred to our emergency service with ruptured abdominal aneurysm. We placed a 34-mm Amplatzer sizing balloon II into the suprarenal level of aorta to immediately control the active massive bleeding and to get the patient out of hemorrhage shock into the stable condition. After the bleeding control, endovascular repair was successfully performed. This is the first case report, to our knowledge, of atrial septal defect (ASD) sizing balloon use for blocking the blood flow through aorta to control the bleeding. ASD sizing balloon has some different properties compared to aortic occlusion balloon catheter (AOBC). Due to availability of sheathless usage, ASD sizing balloon may be preferred over AOBC for some of patient groups with peripheral artery diseases and small femoral artery diameters.

Feasibility and safety of a virtual 3-Fr sheathless-guiding system for percutaneous coronary intervention

OBJECTIVES

To evaluate the feasibility and safety of a virtual 3-Fr system [5-Fr sheathless-guiding catheter (GC)] for percutaneous coronary intervention (PCI).

BACKGROUND

The use of miniaturized devices for PCI is gaining popularity because of increased patient comfort and decreased risk of access site complications.

METHODS

From July 2010 to December 2012, consecutive patients who underwent elective PCI (planned or ad hoc PCI) at our hospital were enrolled. PCI using the virtual 3-Fr system was attempted as our initial strategy, unless a 6-Fr or larger GC was considered to be suitable [lesions with heavy calcification, large (>2 mm) side branches, or chronic total occlusion].

RESULTS

Five hundred sixty-six patients underwent elective PCI during the study period, and 132 patients who met the criteria underwent PCI using the virtual 3-Fr system. Procedures using the virtual 3-Fr system were successful in 126 patients (95%); 111 (84%) were performed using the transradial approach, 110 (83%) were ad hoc procedures, and 45 (31%) were complex coronary lesions (type B2 or C). Six patients required conversion to a conventional 5- or 6-Fr sheath and catheter system. No intraoperative complications occurred, and radial artery patency was achieved in all patients who underwent transradial procedures.

CONCLUSIONS

PCI using the virtual 3-Fr system is a feasible and viable alternative to conventional procedures that use a sheath and GC in appropriately selected patients. This small-caliber system may minimize endovascular trauma, particularly during transradial coronary procedures.

An optically coupled system for quantitative monitoring of MRI-induced RF currents into long conductors

The currents induced in long conductors such as guidewires by the radio-frequency (RF) field in magnetic resonance imaging (MRI) are responsible for potentially dangerous heating of surrounding media, such as tissue. This paper presents an optically coupled system with the potential to quantitatively measure the RF currents induced on these conductors. The system uses a self shielded toroid transducer and active circuitry to modulate a high speed light-emitting-diode transmitter. Plastic fiber guides the light to a photodiode receiver and transimpedance amplifier. System validation included a series of experiments with bare wires that compared wire tip heating by fluoroptic thermometers with the RF current sensor response. Validations were performed on a custom whole body 64 MHz birdcage test platform and on a 1.5 T MRI scanner. With this system, a variety of phenomena were demonstrated including cable trap current attenuation, lossy dielectric Q-spoiling and even transverse electromagnetic wave node patterns. This system should find applications in studies of MRI RF safety for interventional devices such as pacemaker leads, and guidewires. In particular, variations of this device could potentially act as a realtime safety monitor during MRI guided interventions.