Puneeth Shridhar

A Review of PMMA Bone Cement and Intra-Cardiac Embolism

Percutaneous vertebroplasty procedure is of major importance, given the significantly increasing aging population and the higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving the injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main effects of PMMA bone cement on the heart, and the extent of influence of the materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case reports.

Exclusion of Giant Coronary Artery Aneurysm with Covered Stent Combinedwith Coil Embolization of Vessel Outflow

Background: Coronary artery aneurysms (CAA) are rare abnormal dilatation of the coronary arteries. They are termed giant if their diameter exceeds the reference vessel diameter by more than 4 times or if they are more than 8 mm in diameter. If not treated, they have a tendency to rupture, thrombose or embolize. There is however no definite therapy for CAA. Various therapies suggested in the management of aneurysms include surgical resection, covered stent implantation or coil embolization. Methods: We describe a case of coiling of a potential collateral vessel feeding the giant coronary aneurysm retrogradely and covered stenting of main branch to exclude the aneurysm. Results: Transcatheter embolization was successfully done. No late complications were seen during 1 year CT angiography. Conclusion: Dual stent and coil embolization is safe and effective for vessel outflow during the treatment of giant coronary artery aneurysm. Further long term outcomes will have to be determined through serial CT angiographies.

In Vitro Study of a Superhydrophilic Thin Film Nitinol Endograft that Is Electrostatically Endothelialized in the Catheter Prior to the Endovascular Procedure

Electrostatic endothelial cell seeding has evolved as an exceptional technique to improve the efficiency of cell seeding in terms of frequency of attached cells and the amount of cell adhesion for the treatment of vascular diseases. In the recent times, both untreated and superhydrophilic thin film nitinol (TFN) have exhibited strong prospects as substrates for creation of small-diameter endovascular grafts due to their hallmark properties of superelasticity, ultra low-profile character, and grown hemocompatible oxide layer with the presence of a uniform endothelial layer on the surface. The purpose of the current study is to understand the effects of endothelial cell seeding parameters (i.e., applied voltage, incubation time, substrate chemistry, and cell suspension solution) to investigate the cell seeding phenomenon and to improve the cell adhesion and growth on the TFN surface under electrostatic transplantation. Both parallel plate and cylindrical capacitor models were used along with the Taguchi Design of Experiment (DOE) methods to design in vitro test parameters. A novel in vitro system for a cylindrical capacitor model was created using a micro flow pump, micro incubation system, and silicone tubings. The augmented endothelialization on thin film nitinol was developed to determine the effect of cell seeding and deployed in a 6 Fr intravascular catheter setup. Cell viability along with morphology and proliferation of adhered cells were evaluated using fluorescent and scanning electron microscopy. Our results demonstrated that the maximum number of cells attached on STFN in the catheter was observed in 5 V with the 2 h exposure of in the cell culture medium (CCM) solution. The condition showed 5 V voltage with 0.68 × 10−6 µC electrostatic charge and 5.11 V·mm−1 electric field. Our findings have first demonstrated that the electrostatic endothelialization on the superhydrophilic thin film nitinol endograft within the catheter prior to the endovascular procedure could enhance the biocompatibility for low-profile endovascular applications.

A Low-Profile Flow Sensing System for Monitoring of Cerebrospinal Fluid with a New Ventriculoamniotic Shunt

Fetal hydrocephalus is a condition involvingexcessive accumulation of intraventricular cerebrospinal fluidwith ventricular dilation. It often leads to malformation ordevastating neurological consequences of developing fetalbrains. Recent advances in fetal imaging have triggered thedevelopment of a ventriculoamniotic shunt. However, there arestill concerns about shunt clogging or obstruction with theexisting devices. Here, we introduce a low-profile, ventriculoamniotic shunt device, integrated with a microflowsensor to relieve abnormal high intracranial pressure, whileenabling real-time monitoring of the fluid dynamics. The shuntprototype is manufactured by using a low-profile flexiblecomposite tubing and superelastic nitinol anchors. The flexibleand stretchable microflow sensor is uniquely designed andfabricated by using two metallic nanomembranes encapsulatedby biocompatible silicone elastomer. Flow monitoringperformance of the sensor is demonstrated in vitro using acustom-built flow circulation model with a peristaltic pump. The highly sensitive, microflow sensor measures variousincoming fluid velocity from 0.037 to 0.3 m/s, corresponding tothe capacitance changed from 0.49 pF to 1.43 pF. Collectively, we demonstrate the feasibility of a microflow sensor for directintegration with the ventriculoamniotic shunt device for thetreatment of aqueductal stenosis.

Use of Micropatterned Thin Film Nitinol in Carotid Stents to Augment Embolic Protection

Stenting is an alternative to endarterectomy for the treatment of carotid artery stenosis. However, stenting is associated with a higher risk of procedural stroke secondary to distal thromboembolism. Hybrid stents with a micromesh layer have been proposed to address this complication. We developed a micropatterned thin film nitinol (M-TFN) covered stent designed to prevent thromboembolism during carotid intervention. This innovation may obviate the need or work synergistically with embolic protection devices. The proposed double layered stent is low-profile, thromboresistant, and covered with a M-TFN that can be fabricated with fenestrations of varying geometries and sizes. The M-TFN was created in multiple geometries, dimensions, and porosities by sputter deposition. The efficiency of various M-TFN to capture embolic particles was evaluated in different atherosclerotic carotid stenotic conditions through in vitro tests. The covered stent prevented emboli dislodgement in the range of 70%–96% during 30 min duration tests. In vitro vascular cell growth study results showed that endothelial cell elongation, alignment and growth behaviour silhouettes significantly enhance, specifically on the diamond-shape M-TFN, with the dimensions of 145 µm × 20 µm and a porosity of 32%. Future studies will require in vivo testing. Our results demonstrate that M-TFN has a promising potential for carotid artery stenting.

Undervalued Significance of Moderate Enzyme Elevation in Paradoxical Coronary Embolism Secondary to Deep Vein Thrombosis: Short Review

Myocardial infarctions (MI) are relatively common in people with deep vein thrombosis (DVT). In fact, the rate of myocardial infarction has been reported to be greater in adults with DVT as compared to those without DVT and recent studies have shown interest in quantifying the relationship with MI and DVT. However, cryptogenic nature of MI in these individuals is underestimated. Approximately one-fourth of the US populations are estimated to have a patent foramen ovale (PFO). Of note, since MI being the single largest cause of mortality, a large number of these patients have a PFO. The high percentage of myocardial infarction in patients with a PFO has not been addressed in the literature appropriately before and might have been overlooked because most of the patients with infarctions had an uncomplicated course and only moderate enzyme elevation.