Biomaterials and Materials for Medicine

Innovations in Research, Devices, and Applications

Jingan Li, Jingan Li

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000441161
• Edition: 1
• Topic: Technologie et ingénierie
• Subtopic: Sciences biomédicales

Biomaterials and Materials for Medicine: Innovations in Research, Devices, and Applications provides an application-oriented summary of innovations in this rapidly evolving field, offering a view of various directions in biomaterials and medical materials and their advanced uses.

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• Highlights vascular, orthopedic, skin tissue engineering, and nerve tissue engineering biomaterials, including the latest research on therapeutic devices and implants

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• Introduces special stent materials for palliative treatment of esophageal cancer and related technologies of surface modification

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• Discusses use of biomaterials and related designs in drug targeting and controlled release

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• Describes wearable biomedical devices, biomimetic materials, and micronscale and nanoscale biomaterials

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• Details the theoretical calculation and computer simulation of biomaterials as a complementary discipline with physical experimental science

This book is aimed at an interdisciplinary group of researchers working on development and application of biomaterials for medical applications in the fields of materials scientists, biomedical engineering, and medicine.

1 Cardiovascular Therapeutic Devices: Material and Fabrication Progress

Xiao Luo, Dan Zou, and Li Li

Southwest Jiaotong University

DOI: 10.1201/9781003161981-1

Contents

1. 1.1 Introduction
2. 1.2 Devices for Reestablishing Healthy Blood Circulation
   1. 1.2.1 Vena Cava Filter
      1. 1.2.1.1 Permanent Vena Cava Filter
      2. 1.2.1.2 Temporary Vena Cava Filter
      3. 1.2.1.3 Retrievable Vena Cava Filter
   2. 1.2.2 Embolization Devices
      1. 1.2.2.1 Non-absorbable Solid Particle Embolic Material
      2. 1.2.2.2 Absorbable Embolic Material
      3. 1.2.2.3 Mechanical Embolic Material
3. 1.3 Devices for Implementing Revascularization
   1. 1.3.1 Vascular Stent
      1. 1.3.1.1 Major Drugs for DES Platforms
      2. 1.3.1.2 Optimization of DES Surface Coating and Structure
      3. 1.3.1.3 Trials of BRS
   2. 1.3.2 Drug-Coated Balloon
      1. 1.3.2.1 Approaches to Manipulate Tissue Uptake Rate of DCB Drug
      2. 1.3.2.2 Factors Relevant to Tissue Distribution and Resistance of DCB Drug
      3. 1.3.2.3 Alternation of DCB Drugs
   3. 1.3.3 Artificial Blood Vessel
      1. 1.3.3.1 Materials for Artificial Blood Vessel Fabrication
      2. 1.3.3.2 Surface Modification Technologies
      3. 1.3.3.3 Possibilities of Small Diameter Artificial Blood Vessel
4. 1.4 Devices for Restoring Cardiac Hemodynamics
   1. 1.4.1 Artificial Heart Valves Replacement
      1. 1.4.1.1 Mechanical Valves
      2. 1.4.1.2 Tissue Valves
      3. 1.4.1.3 Tissue-Engineered Valves
   2. 1.4.2 Heart Function Recovery
      1. 1.4.2.1 Totally Artificial Heart
      2. 1.4.2.2 Ventricular Assist Devices (VADs)
   3. References

1.1 Introduction

Peace and development are the main themes of the current era. In recent decades, the global social economy has developed rapidly, and the lifestyles of residents have been greatly improved. However, due to long-term unhealthy lifestyles or other congenital factors, the prevalence of cardiovascular diseases has increased significantly. According to a World Health Organization (WHO) survey, cardiovascular disease has become the leading cause of death in the global population, accounting for approximately 30% of the total deaths. Through blood circulation, the cardiovascular system provides the body with oxygen, transports nutrients, and transports metabolic waste. The stable operation of the cardiovascular system is an important guarantee for maintaining the health of the body. For patients suffering from severe heart diseases such as embolism, congenital heart defects, vascular stenosis, and heart failure (HF), effective treatments increasingly rely on therapeutic devices. During the last decades, biomaterial and medical communities have optimized and introduced various materials, as well as structure design and fabrication, approaches. These exploitations enhanced the therapeutic value of the devices, and the clinical success demonstrated great progress in reestablishing healthy blood circulation, implementing revascularization, and restoring cardiac hemodynamics.

There are various methods of cardiovascular treatment devices to deal with different cardiovascular diseases. When dealing with problems such as thrombus blood, filters are selected to remove the blood clots. When faced with tissue lesions caused by abnormal blood vessels, embolization devices are used to create thrombus to block the diseased blood vessels to maintain normal and healthy blood circulation. In dealing with vascular diseases, such as atherosclerosis, vascular stents or drug balloons are used for interventional treatment. Artificial blood vessels are selected to replace diseased blood vessels. For heart hemodynamic disorders caused by abnormal heart function and other reasons, artificial heart valves or ventricular assist devices are used for improvement, and artificial hearts are used for replacement.

In this chapter, the currently adopted/potential materials and methods that modulated the device properties of anti/pro-coagulation, anti-hyperplasia, and mechanical support are summarized and compared (Figure 1.1). The challenges cardiovascular therapeutic devices face and the opportunities that are emerging have also been identified.

FIGURE 1.1 Scheme of medical devices applied to cardiovascular therapy. (a) reestablishing healthy body circulation, (b) implementing revascularization, and (c) restoring hemodynamics.

1.2 Devices for Reestablishing Healthy Blood Circulation

Maintaining and reestablishing healthy blood circulation is the primary goal of cardiovascular therapeutic devices. There are different vascular lesions due to different causes, and therapeutic devices encounter different and complex situations. Thrombus is the most common problem that needs to be dealt with. However, thrombus plays a role as a double-edged sword that cannot be arbitrarily defined as good or bad (as shown in Figure 1.2). Under certain conditions, a filter can be applied to blood clots; and under other conditions, an embolization device can be deployed to produce the thrombus to block the diseased blood vessels.

FIGURE 1.2 Thrombus for reestablishing healthy blood circulation.

Here, we introduce two typical cardiovascular therapeutic devices: vena cava filter (VCF) and embolization device, which were specifically used for thrombus to maintain and reestablish a healthy blood circulation.

1.2.1 Vena Cava Filter

Pulmonary thromboembolism (PTE) is mainly caused by deep vein thrombosis (DVT). The main pathogenic mechanism is that abnormal blood coagulation in the deep vein cavity blocks the lumen and obstructs venous reflux by forming a thrombus. Thrombus passes through the vena cava and enters the pulmonary circulation through the heart. Then, large blood clots cause blockages and insufficient blood supply to the lung.

There are some commonly used methods to prevent large thrombus from entering the pulmonary circulation, such as dissolving the thrombus, or using mechanical methods (e.g., VCF) to capture and artificially block its transportation route. The main principle is to place a filter in the blood vessel to catch thrombus, especially the relatively large thrombus, so that it cannot enter the heart and pulmonary circulation, thereby avoiding pulmonary embolism.

The filter has the following characteristics: (1) the filter is usually designed as an umbrella- or a cone-shaped structure which can keep the blood pressure and flow changes without any risk even it has been filled. Meanwhile, blood flow parallel to the axis can inhibit the growth of the thrombus and break the thrombus, ensuring healthy blood circulation. (2) The conveying device has a small impact. (3) The filter can stably capture thrombus. Sometimes the source of thrombosis is the thrombus that has been captured. For life-threatening thrombus, the filter should have high and stable capture efficiency. Some filters allow a small amount of other small thrombi to pass, thereby avoiding the excessive accumulation of trapped thrombus and forming the filter embolism.

According to clinical use, three types of VCF products are available in the market: permanent, temporary, and optional recyclable VCF. Their material and structural design directly affect the clinical effect.

1.2.1.1 Permanent Vena Cava Filter

Metal VCF was first used clinically in the 1980s. Once this type of filter is placed, it cannot be removed without an operation. Representative products include Greenfield [1], Bird’s Nest [2], VenaTech LGM [3], Simon [4], and TrapEase [5].

1. Greenfield filter (GF)
   In 1973, Greenfield used an umbrella filter for clinical use. To date, GF is the most widely used filter available in the market and has become the reference structure for later filter designs.
   The first-generation GF filter adopts an overall tapered design, with a hook at the tail end of the strut, which is anchored on the vessel wall by the hook. It is placed by surgically incising the internal jugular vein or femoral vein. According to the geometric principle, more than 50% of the open section can still be maintained even if the thrombus fills 70% of the total length of the upper end of the cone. Therefore, the design of the GF ensures smooth blood circulation in the vena cava and captures clinically significant thrombi.
2. Bird’s Nest filter (BNF)
   In 1989, Cook Medical launched a new type of filter in the United States under the trade name Bird’s Nest filter (BNF). The stainless steel wire of this filter is randomly bent into a net-like structure, similar to a bird’s nest.
3. VenaTech LGM filter
   The first-generation LGM filter was designed and developed by LG Medical and was launched in France. The filter is made of a bio-/magnetic resonance imaging-compatible alloy Phynox (cobalt, chromium, iron, nickel, molybdenum) by stamping and spot welding. Six slightly curved alloy sheet bases are connected to a flat side, and the side rails are attached to the wall of the vena cava to provide stable support.
4. Simon nitinol filter (SNF)
   SNF is the first nickel-titanium alloy filter on the market. The alloy is composed of 53% nickel, 45% titanium, and 2% cobalt. This material is relatively soft at room temperature, but has thermal memory and can be restored to the original shape at body temperature. This alloy is corrosion-resistant, non-ferromagnetic, and stronger than steel, making it a suitable material for preparing VCFs.
5. TrapEase filter (TEF)
   This filter is integrated by laser cutting nickel-titanium alloy tubes. It has a symmetric...