Biomechanics of Artificial Heart Valves

Today Cardiac surgery has advanced tremendously to enable repair of all cogenital heart defects, replacement of damaged hear valves and bypassing of coronary blocks.

• About 1 in 100o babies is born with deformed heart and 1/3 of them died in infancy.
• The imperfect functioning of the heart valve is due to various defects like hole  in the heart , arterial septal defects and ventricular septal defects.
• when the major vessels of the heart are wrongly  connected, then there is mixing of pure and impure blood.

Normal heart valve

Prosthetic valves:- 

• These are made from high grade plastic and metal.
• they need life long coagulating agent blood thinning agent. 
• the average durability of these valves is about 8 to 10 years.

Tissue valves:-

• They may be neither homograft or heterograft.
• homograft valves are taken from human beings.
• heterograft valves are taken from animals.
• Here blood thinning s not necessary.
• The average durability of these valve is smaller than the prosthetic valves.

Artificial pig valve

•   Heart valves prevent the backflow of blood, which ensuresthe proper direction of blood flow through the circulatory system. Without these valves, the heart would have to work much harder to push blood into adjacent chambers. The heart is composed of 4 valves

1. The Tricuspid valve is between the right atrium and right ventricle.
2.  The Pulmonary valve is between the right ventricle and the pulmonary artery.
3.  The Aortic valve is between ventricle and the aorta .
4.  The Mitral valve is between the left atrium and left ventricle. It opens and closes to control
   blood flowing into the left side of the heart.

Requirements for the design of artificial heart valves:-

• When the artificial heart valve is in contact with the blood , there would not be any hemolysis or blood clots.
• The valve material must be tough enough to withstand the heart beat rate thrugh out the life of the patient.
•  It should be designed small, light, reliable and efficient enough to enable it to be inserted surgically into the heart.

  

  Aortic valve

Mechanical Heart Valve:-

• Prosthetic Heart Valves are fabricated of different biomaterials. 
• Biomaterials are designed to fit the peculiar requirements of blood flow through the specific chambersof the heart, with emphasis on producing more central flow and reducing blood clots. 
• Some of these biomaterials are alumina, titanium, carbon, polyester, polyurethane...
• The mechanical properties of these biomaterials involve how a material responds to the application of a force. 
• The three fundamental types of forces that can be applied are stretching (tension), bending, or twisting. 
• Materials respond to the forces by deforming (change in shape). 
• An elastic response is reversible, while an inelastic response is irreversible. In the elastic region, an elastic modulus relates the relative deformation a material undergoes to the stress that is applied. 
• The transition between elastic deformation and failure occurs at the yield point (or stress) of the material. In designing a component with the material, an inelastic response is considered failure. 



Leaflet valve

• Failure can be plastic deformation or ductile failure. It can also be breaking, including brittle failure or fracture.

• Mitral Valve Replacement Valve replacement is done when valve repair is not possible.Artificial Heart valve is the last solution for people with a damage heart valve caused by any disease as regurgitation.In valve replacement surgery, an artificial prosthetic valve replaces the damaged mitral valve. The two types of artificial valves are mechanical and tissue. Mechanical valves, which are made of biomaterials,

  

  artificial mitral valve

  
  may last a long time. However the patient with a mechanical valve must use an anticoagulant medication such as warfarin (Panwarfin) for the rest of life to prevent blood clots from forming on the valve. If a blood clot forms on the valve, the valve won’t work properly. If a clot escapes the valve, it could lodge in an artery to the brain, blocking blood flow to the brain and causing a stroke. Tissue valves are made of biological tissue such as a pig’s valve. These kinds of valves are called bioprostheses. These may wear out over time and may need to be replaced in another operation. However the tissue valve can avoid use of long-term anticoagulation medication. Mitral valve repair or replacement involves open-heart surgery. Through an incision in the breastbone (sternum), the heart is exposed and connected to a heart-lung machine that assumes the breathing and blood circulation during the procedure. The surgeon then replaces or repairs the valve. After the operation, which lasts several hours, the patient spends one or more days in an intensive care unit, where the general recovery is closely monitored.

Implantable artificial kidney

Hemo Dialysis:- 

 

The goal of Hemo Dialysis is to replace the kidneys’ excretory function. To accomplish this goal, blood and dialysate are circulated in opposite directions (counter current) on opposite sides of a semipermeable membrane in the dialyzer  allowing unwanted solutes such as potassium, urea, and phosphorus to diffuse from the blood into the dialysate and permitting addition of solutes such as bicarbonate and calcium from the dialysate into blood. 

The concentrations of the solutes added to the dialysate mirror those normally maintained in the body by the native kidneys. An additional goal is the elimination of excess water volume via ultrafiltration, accomplished by controlling the hydrostatic pressure gradient across the semipermeable membrane .
 
Implantable Artificial kidney:-
The artificial kidney project, which is targeted for clinical trials in 2017, was selected for its transformative potential in treating end stage renal disease and for its potential to benefit from early interactions with the FDA in the approval process.

End-stage renal disease, or chronic kidney failure, affects nearly 2 million people worldwide, including more than 570,000 in the United States, and costs the nation almost $40 billion each year for treatment. The most effective treatment is kidney transplantation, but those organs are in short supply; last year, only 16,812 kidneys were available for transplant, leaving 92,000patients on the waiting list, according to the Organ Procurement ant Transplant Network.
The UCSF artificial kidney, or implantable Renal Assist Device (iRAD) would include thousands of microscopic filters as well as a bioreactor to mimic the metabolic and water-balancing roles of a real kidney.

Implantable Artificial Kidney

Transesophageal Echocardiography

CX50 xMATRIX

• The CX50 xMATRIX, that features Live 3D TEE (transesophageal echocardiography).
• Philips has betrayed its first portable ultrasound.
• CX50 xMATRIX is very compact than iE33 xMATRIX.
• In clinical evaluations the Live 3D TEE image quality is excellent and, with the new user interface, 3D imaging is really intuitive. In imaging TAVR procedures with the CX50, I am able to easily switch back and forth between 2D and 3D during the critical time when we are positioning the valve.
• The new CX50 xMATRIX is a versatile system that provides hospitals with high quality portable imaging to promote better patient care..

Advantages:-

v    Portable

v    Reliable

v    Versatile

v    Compact in size

                                   

Features:-

Along with the new CX50 xMATRIX, Philips announced the Vision 2013 upgrade for existing CX50 cardiology customers.  Vision 2013 includes:

• Qlab 9.0 with improved speckle tracking algorithm for faster, more robust strain quantification
• Available C8-5 and L12-5 50mm transducers for specialized vascular imaging requirements.
• Available S12-4 and S8-3 sector transducers for pediatric and neonatal imaging.
• New pediatric analysis and structured reporting capabilities.
• Vascular structured reporting.
• Improved annotations and workflow.

Chronic wound care

• Wound healing is a complex and dynamic process of restoring cellular structures and tissue layers. There are two types of wounds: acute and chronic. Acute wounds are either traumatic or surgical and move through the healing process at a predictable rate from insult to closure. Chronic wounds do not progress through the predictable stages of wound healing.

• The type of wound repair is classified as either primary, secondary, or tertiary intention. In primary intention, the wound edges are approximated and held together with staples, sutures, or some form of adhesive tape. Healing occurs with epithelialization and connective tissue attachments, usually without complications.

•  A chronic wound is a wound that has not resolved over a reasonable period of time no matter the cause.Changes occur within the molecular environment of a chronic wound that are not conducive to healing, such as high levels of inflammatory cytokines, proteases, and low levels of growth factors. These changes terminate the healing process and increase the potential for septic infections. Addressing the issues that might be responsible for the physiological wound changes may restart healing

The skin is the largest organ of the body and is continually adapting to meet the needs of an ever-changing external environment. 

 WOUND HEALING PHASES:-

nBegins within 24 hours of the initial injury and may continue for up to 21 days

nIt is characterized by three events:

• nInflamation

• Proliferation

exudate
• n

n

• nMaturation

Inflamation

•  Characterized by redness, heat, pain and swelling
  nLast approximately 4 to 5 days
  nInitiates the healing process by stabilizing the wound through platelet activity that stops bleeding & triggers the immune response

 PROLIFERATION:-

 

• Epithelization:- 

 

nFormation of an epithelial layer that seals and protects the wound from bacteria and fluid loss

nIt is essential to have a moist environment to foster growth of this layer

nIt is a very fragile layer that can be easily destroyed with aggressive wound irrigation or cleansing of the involved area .

 

 

Granulation:-

 

nFormation of new capillaries that generate and feed new tissue

nGranulation tissue is the beefy red tissue that bleeds easily.

 

Maturation:-

 

nFinal stage of wound healing

nBegins around day 21 and may continue for up to 2 years

nCollagen synthesis continues with eventual closure of the wound and increase in tensile strength

nTensile strength reaches only about 80% of pre-injury strength

nCreates a support matrix for the new tissue that provides it with its’ strength

n

nOxygen, iron, vitamin C, zinc, magnesium & protein are vital for collagen synthesis

n

nThis stage is the actual rebuilding and is influenced by the overall patient condition of the wound bed.

 

 

Red light therapy

 

 

  Red Light Therapy for Healing
Aside from its cosmetic and anti-aging benefits, RED light therapy can provide relief from chronic and acute pain including muscle pain, joint pain, arthritis, high blood pressure, tissue and nerve damage, and can decrease injury healing time. Originally discovered by NASA for this purpose, RED light therapy is now used by professional athletes to promote healing with powerful results.

Collagen:-

collagen

• Collagen produces through its porous structure a capillary suction effect and absorbs the discharge from the wound. The discharge from the wound dissolves the porous structure and releases the native collagen. This accelerates the building of new granulation tissue in the granulation phase.

• Collagen has an indirect influencing control on the epithelization and regeneration phases by stimulating the body`s own collagen synthesis, accelerating the epithelization process considereably.

.

n

vscan 1.2

Vscan is a pocket-sized visualization tool providing black and
white anatomic and color-coded blood flow images in real
time. It can easily be integrated into physical examinations
allowing physicians to add a visual inspection into the body.
The images are generated based on ultrasound technology .

 

DEVICE

• Up to 50% more scan time compared with the Version 1.1 release
• More intuitive user interface, enabling fingertip control and faster workflow
• Enhanced contrast resolution allowing for crisper images of abdominal and OB presets

NEW FEATURES
Device
1) Up to 50 percent more scan time compared to the Vscan version 1.1 release
2) New intuitive user interface, enabling fingertip control and faster workflow
3) Enhanced contrast resolution allowing for crisper images of abdominal and OB presets

APPLICATIONS OF VSCAN1.2 

• Urology
• Cardiac
• Abdominal
• pediatric
• thoracic
• pleural motion and fluid detection
• peripheral vascular applications.

Cancer

Cancer is in which the body cells become abnormal and divide without control.normal cells divide faster to allow the person to grow during the early years of the persons life. When the person become adult, most cells become rapidly divide only to replace to repair injuries.

Cancer starts by:

• Instead of dying, cancer cells continue to grow and form new abnormal cells.
• cells become cancer cells because of damage to DNA.
• In most cases the cancer cells form a tumor.

Cancer can spread via:

Cancer cells often travel to other parts of the body, where they begin to grow and form new tumors that replace normal tissue. This process is called metastasis. It happens when the cancer cells get into the bloodstream or lymph vessels of our body.

Half of all men and one-third of all women in the US will develop cancer during their lifetimes.
Today, millions of people are living with cancer or have had cancer. The risk of developing most types of cancer can be reduced by changes in a person's lifestyle, for example, by quitting smoking, limiting time in the sun, being physically active, and eating a better diet. The sooner a cancer is found and treated, the better the chances are for living for many years.

Cancer is not contagious because....

  In the past, people often stayed away from someone who had cancer. They were afraid they might "catch" the disease. But cancer is not like the flu or a cold. You cannot catch cancer from someone who has it. You will not get cancer by being around or touching someone with cancer. Don't be afraid to visit someone with cancer. They need the support of their family and friends.

Types of cancer's:

• Breast cancer
• Bone cancer
• Anal cancer
• appendix cancer
• urethral cancer
• gastric cancer
• cervical cancer
• gall bladder cancer
• colon cancer
• germ cell cancer
• skin cancer
• bile duct cancer
• vaginal cancer
• heart cancer
• thyroid cancer
• lip cancer
• endometrial cancer
• vulvar cancer
• eye cancer
• head & neck cancer
• lung cancer 
• liver cancer
• mouth cancer
• laryngeal cancer
• nasopharyngeal cancer
• ovarian cancer
• penile cancer
• pancreatic cancer
• retinoblastoma cancer
• parathyroid cancer
• renal cell cancer
• colorectal cancer 
•  

Causes of cancer:

•  Radiation 
• Hormones
• Physical agents
• Heredity
• Chemicals
• Infection
• Diet

Symptoms:

• Lung cancer can cause the blockage of the bronchus resulting in cough,pneumonia.
• colorectal cancer blockages in the bowel, resulting in changes in the bowel habits.
• esophageal cancer can cause narrowing of the esophagus making it difficult or painful to swallow.
• Ulceration can cause bleeding which, if it occurs in the lung, will lead to coughing up blood,in the bowels to anemia or rectal bleeding, in the bladder to blood in the urine, and in the uterus to vaginal bleeding.

Prevention:

•  Avoid taking of tobacco.
• Drinking alcohol is also linked to a higher risk of certain types of cancer. 
•  The combined use of alcohol and tobacco raises the risk of mouth, throat, voice box, and esophagus cancer far more than the effects of either drinking or smoking alone. 
• Staying out of the sun between the hours of 10 a.m. and 4 p.m.
• Wearing a hat, shirt, and sunglasses when you are in the sun
• Using sunscreen with a sun protection factor (SPF) of 15 or higher
• Not using tanning beds or lamps
• Limit processed meats (such as bacon, deli meats, and hot dogs)
• Choose foods to help stay at a healthy weight
• Eat a lot of fresh fruits and vegetables (at least 5 servings a day)
• Choose whole grains rather than refined grains and sugars
• Limit red meats (beef, pork, and lamb)
•  Limit alcohol intake to 1 alcoholic drink a day or less for women and 2 or less for men 

Treatment:

surgery:

• Radiation therapy.
• Chemo therapy.

Cavity filling

To treat a cavity dentist will remove the decayed part of the tooth and then fill in that region.Fillings are also used to repair cracked or broken teeth and teeth that have been worn down from misuse.

Temporary fillings:

 Temporary fillings are just that; they are not meant to last. They usually fall out, fracture, or wear out within a month. Be sure to contact your dentist to have a temporary filling replaced with a permanent one. If you don't, the tooth could become infected or you could have other complications.

   Temporary fillings are used under the following circumstances:

1. For fillings that require more than one appointment i.e before placement of gold fillings and for certain filling procedures (called indirect fillings) that use composite materials
2. Following a root canal
3. To allow a tooth's nerve to "settle down" if the pulp became irritated
4. If emergency dental treatment is needed.

Types of filling materials:

• Cast gold.
• Silver amalgam.
• Ceramics.
• Tooth colored composites.
• Glass ionomer.
   

 

Problems with fillings

 Pain and Sensitivity

•  A tooth may be sensitive to pressure, air, sweet foods, or temperature. Usually, the sensitivity resolves on its own within a few weeks. During this time, avoid those things that are causing the sensitivity. Pain relievers are generally not required.
• Pain around the fillings can also occur.
• If you experience pain when you bite, the filling may be interfering with your bite. You will need to return to your dentist and have the filling reshaped.
  
  • If the decay was very deep or close to the pulp of the tooth, you may experience a "toothache-type" pain.
  • This "toothache" response may indicate this tissue is no longer healthy. In this case, a root canal may be required.

Filling allergies:

 Allergic reactions to silver fillings are rare. Fewer than 100 cases have ever been reported, according to the ADA. In these rare circumstances, mercury or one of the metals used in an amalgam restoration is thought to trigger the allergic response.Patients who suffer amalgam allergies typically have a medical or family history of allergies to metals.

Caring of teeth after filling:

  To maintain fillings, you should follow good oral hygiene practices -- visiting your dentist regularly for cleanings, brushing with a fluoride tooth paste, and flossing at least once daily. If your dentist suspects that a filling might be cracked or is "leaking" (when the sides of the filling don't fit tightly against the tooth, this allows debris and saliva to seep down between the filling and the tooth, which can lead to decay), he or she will take X-rays to assess the situation. If your tooth is extremely sensitive, if you feel a sharp edge, if you notice a crack in the filling, or if a piece of the filling is missing, call your dentist for an appointment.