clinical problems requiring implants.pptx

Implants

1. Coronary artery disease Coronary artery disease is a multi-factorial condition, resulting from the convergence of genetics, environment, diet, and lifestyle. Recognized risk factors for the development of ischemic heart disease include family history, high blood pressure, smoking , elevated low-density lipoprotein (LDL) cholesterol, diabetes, physical inactivity , and obesity . Atherosclerosis begins at the vascular walls of the coronary arteries, the blood vessels which run over the surface of the heart. Each coronary artery is critical for supplying oxygenated blood to the highly active cardiac muscle, also known as myocardium

2. Implant for Coronary artery disease A minimally invasive device for opening blocked coronary arteries, known as the coronary stent, has been developed more recently to avoid many of the complications of bypass surgery. A typical stent is formed as a mesh tube, constructed from metal wire commonly made of stainless steel or other metals . Patients suffering from coronary artery disease can now be treated with minimally invasive stents that are even more effective and biocompatible, as a resultof biomaterial innovations 2 types of stents commonly used Bioactive stents Degradable stents

3. Bioactive Stents Bioactive stents are biomaterials that combine the mechanical properties of coronary stents with the functional properties of biomolecules such as pharmaceuticals,cytokines , and antibodies. The main motivation for bioactive stent development is to reduce complications associated with stent implantation. Bare-metallic stents,while permitting targeted treatment for occluded coronary arteries, are associated with high rates of restenosis (i.e., re-narrowing of the coronary artery ).

4. Degradable Stents Though bioactive stents are making great strides in saving patients from coronary artery disease, there is evidence that their permanent implantation in the arterial wall can have adverse long-term consequences. For this reason, biomaterials researchers are increasingly turning their attention toward degradable stents. Clinicians generally agree that the mechanical reinforcement provided by a stent is needed only temporarily during the healing period . The artery heals between 3 and 6 months after stent implantation, after which arterial support is no longer needed. A functional device that can disappear is clearly preferable over a permanent device that presents the risk of triggering late complications such as restenosis and thrombosis.

5. Stroke Stroke, also known as cerebrovascular accident or “brain attack,” is a clinical condition caused by disruption in blood flow to a portion of the brain . An interruption in blood supply to the brain leads to tissue destruction and cell death, almost instantaneously. Strokes are classified into two categories depending on the underlying pathological process: an ischemic stroke results from occlusion of a blood vessel ,while a hemorrhagic stroke results from rupture and subsequent leakage of a blood vessel

6. Diagram of hemorrhagic stroke resulting from blood vessel rupture within the brain

7. Implants For Nerve Regeneration Both ischemic stroke and hemorrhagic stroke wreak destruction on delicate brain tissue, leaving behind the scars of neuronal deterioration and permanent neurological deficits. The central nervous system has little ability to regenerate and repair.

8. An ideal biomaterial for stimulating nerve regeneration should mimic the mechanical properties, physical dimensions, and electrical conductivity of native axons . The biomaterial must additionally have sufficient biocompatibility for successful brain implantation and must limit glial scar formation so that tissue functionality can be maximized. Nanoscale biomaterials are excellent candidates for neural regeneration, as nanomaterials can accurately simulate the dimensions of biological structures. Nanomaterials are unique among biomaterials in that only nanoscale scaffolds can mimic the surface properties and topography of natural tissues. Since physiological tissues and organs are nanometer in dimension and cells directly interact with and create nanostructured extracellular matrices, nanomaterials are appropriate biomimetics for inducing neuronal growth and guiding brain regeneration

9. Lung Cancer Lung cancer, like all cancers, is a disease of uncontrolled cellular proliferation and unchecked tissue growth. Tumor growth may lead to compression and disruption of local anatomical structures of the lung, as well as invasion of adjacent tissue, and infiltration beyond the lungs in a process known as metastasis . Cancerous lung tumors are caused by chronic exposure to inhaled irritants and carcinogens; noxious agents such as tobacco smoke inflict repeated injury on lung tissues. This exposure triggers a reactive and inflammatory process, eventually resulting in alterations to the DNA of pulmonary cells. As genetic alterations accumulate, lung cells transform from a normal phenotype into a malignant phenotype. When the process involves the full thickness of the lung mucosa, carcinoma in situ is present. Infiltration of malignant cells into the underlying stromal tissue signals the first sign of invasive cancer.

10. Passive Targeted Drug Delivery For Lung cancer Nanoscale biomaterials have recently emerged as novel systems for targeted drug delivery to cancerous tumors. In particular, polymeric micelles in the diameter range of 10–100 nm have the ability to solubilize hydrophobic chemotherapeutic molecules and carry the therapeutics specifically to solid tumors. Such nanoscale carriers take advantage of the “enhanced permeability and retention” effect