HALO received national attention The Doctors TV show with a segment on HALO. “One Life to Live” soap star Crystal Hunt (“Stacy”) was shown having the HALO procedure and was presented her results in front of the live audience. Show host Dr. Lisa Masterson gives an enthusiastic overview of what HALO is all about.
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Know your breast cancer risk! So many women don’t know the facts, here are some resources to keep you in tune with breast cancer. The first step to prevention is education…
Know Your Breast Cancer Risk is a blog maintained by a breast cancer medical device company with articles by doctors, so you know you’re reading pertainent information. Learn from a doctor for free from this great community blog sponsored by Neomatrix, LLC.
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Heart failure (HF) is a condition in which the heart’s ability to fill or pump a adequate amount of blood is impaired. It can be caused by a number of factors including hypertension (high blood pressure), valve failure, coronary artery disease, and many more things. In the figure below, heart failure is shown to be caused by thickened myocardium (myocarditis), which may be a direct result of a viral infection that can cause the muscle to become inflamed. Almost 2% of the American population has heart failure and even with the best therapy, HF still has an annual mortality of 10%.
Treatment of HF depends on the stage of the disease’s progression and is rated on a scale from case I to case IV. The five year survival rate of patients in stage IV is only 20%, therefore this is considered severe heart failure. There are several minimally invasive devices used in HF treatment. The most common treatment device is an artificial pacemaker (shown below), which successfully prevents about 50% of all heart failures from re-occurring. Another treatment option for HF that is extreme is a heart transplant. This is called the “Gold Standard” treatment because it is the best to use, however the availability of donors is slowly declining while the number of patients who need a transplant is steadily rising. Only about 2200 heart transplants are preformed every year.
The ideal solution would be an artificial heart…In 1985, at the University of Pittsburgh Medical Center (UPMC), the first artificial heart was implanted. Five years later, UPMC was the first medical institution to release a patient with a ventricular-assist device (VAD) (shown below). Today, VADs called positive displacement pumps are the leading treatment therapy for HF patients. Dr. Marc Simon presented the idea of positive displacement pumps at the BMES Conference and spoke of future improvement for these devices. He announced that second and third generation prototypes are currently underway in many institutions and will be ready for release soon. Dr. Simon discussed that there is an ideal period during HF in which it is ideal to implant there devices into the patient in order to maximize recovery success. There is a certain point in HF in which an acute, catastrophic event leads to sudden progression of the disease, eventually leading the patient to death. The closer researchers are able to pinpoint the time immediately prior to this turn of events to implant the device, the greater the patient’s chances are for survival.
-Amy
What is Atherosclerosis?
Atherosclerosis is a disease where lipoproteins, which are plasma proteins that carry triglycerides and cholesterol, collect on the inner wall of arterial blood vessels. It is a chronic inflammatory response in the walls in which the lipoproteins harden and form plaque within the arteries. There are three different types of atheromatous plaque. One type is simple cholesterol crystals that build up along the wall and narrow the diameter of the artery. The second type is called an atheroma, which is a nodular accumulation of flaky, yellow material (which is composed mostly of macrophages) in the center of large plaques at the lumen of the artery. The last type of atheromatous plaque is calcification of the outer base of more advanced lesions.
Atherosclerosis is caused by many factors, some of which can be controlled by the patient. Hypertension, obesity, smoking, diabetes, high cholesterol, and congenital heart disease can all be individual or combined causes of atherosclerosis in a patient. Depending on where in the body plaque builds up, symptoms may include angina, heart attack, severe pain, stroke, and/or dizziness.
Significance of Atherosclerosis
Atherosclerosis progresses slowly and is cumulative over time, beginning with macrophage infiltration into the artery. A fatty streak results and a lesion advances to eventually create an atheroma, as shown in the figure below. This continues to advances to create a larger, more complicated lesion. Over time, if the lesion is not treated, the plaque will suddenly rupture and form a thrombus that severely slows down, or even stops blood flow. This can lead to an infarction, which is death of the tissues feeding off of the artery within five minutes if it is not tended to immediately.
In the United States alone, atherosclerosis leads to the death of almost 15,000 people every year. It is also the cause of hospitalization for 20,000 patients per year and over 730,000 physician office visits per year.
Current Treatments
Current treatments include improvements in diet, cholesterol reduction medication, anticoagulate medication, blood pressure medication, surgical procedures and sometimes even gene therapy. Our medical device plans to make improvements upon the current surgical procedures, which are endarterectomy, angioplasty, bypass surgery, and thrombolytic therapy.
In my previous article, The Basics of Heart Failure, it was mentioned that a ventricular-assist device (VAD) is the primary treatment for heart failure. Dr. William Wagner (who also contributed to the positive displacement pump technology previously mentioned) believes that there is much room for improvement in the biocompatibility of VADs. he spoke at the BMES conference of infection and thrombosis (blood clotting) problems upon implantation of VADs into patients.
Infection due to VADs can be caused by the biomaterial used, poor sterile technique, device failure, and percutaneous line design. Shear forces caused by excessive bleeding upon implantation of the device can also cause infection, and infection leads to tissue necrosis.
Thrombosis and thromboembolism are problems that all devices face when coming into contact with blood. To avoid this issue, surgeons use drugs like Heparin or Coumadin to avoid coagulation when devices come into direct contact with the blood.
Many scientists believe that nothing can be solved unless it can be quantified. Infection and thrombosis (believe it or not) can be crudely measured through microembolic signals (MES). Dr. Wagner suggested that scientists should get more out of animal models by analyzing MES, explants, and gross neurological health more thoroughly to minimize plately aggregation and avoid thrombosis. An example of a thoroughly tested device that has been underway for 30 years is the Heartmate II, which is implanted in the chest to aid the heart in pumping (shown in the figure above). This device can be used as a treatment method for patients with severe heart failure, or as a bridge until a transplant is available. When tested in calves, this device showed a spike in platelet aggregation (which is expected and normal) and then a steady decrease in aggregation due o microaggregates leaving the implant site. In previous VADs, the platelet aggregation spiked and then didn’t decline at a steady enough rate for thrombosis to cease. Another research project underway by EvaHeart to improve the downfalls of VADs is to replace bovine (cow) with ovine (sheep) products due to this superior configuration of ovine tissue (methacryloyloxyethyl phosphorylcholine).
-Amy
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Creating Your Perfect Day
When preforming surgeries, an obstacle that has to be dealt with is making sure that the patient;s blood doesn’t coagulate (or thicken) when it comes into contact with metal intruments. This is currently dealt with by a drug called heparin, which thins the blood so that it doesn’t have an adverse reaction to the touch of an instrument. Heparin is widely used and is successful…most of the time. It creates negative reactions in three to ten per cent of all patients in which the blood will coagulate and clot up all around an instrument as soon as direct contact is made. The image below shows that when Heparin fails, coagulation occurs and the device used in surgery is covered with blood clots:
At Brigham Young University, BYU, an alternative solution has been found. Dr. Kenneth Solen and Jared Parker, biomedical engineers who have dedicated much time to this problem, believe that a different type of precaution needs to be taken. They suggested that rather than adding something to the blood that may induce an immune reaction, they would like to remove something. There exist specific proteins in the blood that carry a strong electrical charge in order to cause coagulation. One could conclude that to remove these proteins, something with a negative charge must be utilized. Therefore, the research team used a negatively-charged gel to attract and remove these coagulation proteins, while leaving the rest of the neutral and negatively-charged proteins in the blood. In the lab, this was proven to be successful, however human testing has not been conducted yet. Dr. Solen continues to pursue the perfection of this innovation at W.L. Gore.
After Dr. Solen’s anticoagulation method, the device used in surgery remains clear of blood clotting:
I would like to thank Blake Ferguson for sharing this article with me.
-Amy
Coronary Artery Disease and Coronary Bypass Grafting
Coronary artery disease (CAD) is the leading cause of death for both men and women in the United States. The process of atherosclerosis is the hardening of an artery due to a lipid build up, resulting in functional loss. Fatty deposits, or plaques, may accumulate inside the arterial wall and cause stenosis, or an abnormal narrowing the artery wall. This causes the flow of blood to be reduced or completely stop and the vessel wall to lose its flexibility and ability to handle pulsatile flow. There are several forms of treatment available for CAD depending on the severity of the disease, including lifestyle changes, medicines, angioplasty, and coronary artery bypass grafting (CABG).
CABG is the preferred treatment for patients with multiple areas of coronary artery narrowing or blockage and also for patients with higher percentages of stenosis, this relation can be seen in figure 1 above. Patients typically have 1 to 5 bypasses within one surgical procedure. This form of treatment is the most common type of surgery in the United States, with about 500,000 surgeries per year. Typically, the patient’s saphenous vein from the leg, internal mammary artery (IMA), or the radial artery from the arm is used. Figure 2 shows the location of the saphenous vein and IMA. These vessels are removed and grafted onto the hardened artery to revascularize the affected area.
Figure 2
Advantages and Disadvantages of the Current Gold Standard
The current gold standard for the CABG procedure is the use of autologous (from self) saphenous vein and IMA because of their resemblance to the native coronary artery and their relatively high patency rates. It was not until recently that the radial artery has been widely studied as another source for this procedure. The five and ten year artery patency rates for these have all shown to be greater than 70% and 50%, respectively. These rates vary depending on the blood vessel used for the procedure.
Even with the success this procedure has had, there are several disadvantages that may lead to complications. Removing an autologous vein for the procedure may cause donor site morbidity, which can lead to problems such as groin infection near the site of the saphenous vein removal. In addition, there is only a limited supply of donor vessels for this procedure. Up to 30% of patients undergoing lower limb bypass do not have a suitable vein. This can be problematic for patients who need multiple CABGs or have had previous procedures. There is also a greater risk with the use of multiple vessels. For example, there are more incidents of deep sternal wound infection when both IMAs are used for this procedure, especially for patients with obesity and diabetes.
Existing Vascular Grafts and Improvements
Although living autologous vessels seem to be the ideal conduits for CABG, there are several factors, as discussed above, which have prompted efforts to develop a more suitable donor vessel. The ideal blood vessel substitute should mimic the characteristics of a native blood vessel, including its composition, structure, function, and mechanical properties. It should be durable enough to endure the mechanical stresses, as well as the threat of biodegradation and infection within the body after implantation. The vessel should be made up of materials that promote cell-specific interactions and needs to be able to have similar viscoelastic properties as a normal artery to avoid a compliance mismatch. It should be flexible in order to maintain its contour, yet rigid enough to prevent kinking. The materials used, especially on its luminal surface, must be nonthrombogenic to prevent blood clotting in the vascular graft. It is favorable that the vessel is easily and quickly manufactured, and should be readily available in multiple lengths and sizes.
However, no existing conduit possesses all the properties and qualities of the ideal arterial vascular graft listed above. Current alternatives to autologous vascular grafts are prosthetic conduits based on expanded polytetrafluoroethylene (ePTFE) and polyethylene terephthalate (Dacron ®). Their patency at 5 years is 40% to 50%, which is acceptable but relatively low. Tissue engineering has proven to be successful in wound management, burns, and cartilage repair; therefore their has been a growing interest in designing biological blood vessels as an alternative to autologous vascular grafts and current prosthetic conduits. However, previously proposed and designed tissue engineered vascular grafts were not durable, were prone to early thrombosis, and had poor patency rates. This means that a new vascular graft with all the above mentioned qualities is yet to be manufactured, but is a hopeful potential cure for the future.
Sleep apnea is a disorder in which pauses in breathing occur for about 10 to 30 seconds during one’s sleep (
There are two types of sleep apnea: obstructive and central. Obstructive sleep apnea (OSA) occurs in one out of every five people and is caused by an obstruction in the throat. The obstruction is any physical hindrance in the airway, this can be caused by anything from obesity to enlarged tonsils. People who are more vulnerable to OSA are men, overweight individuals, and individuals over the age of 40. Central sleep apnea (CSA), the main focus of this paper, is caused by an error in the thalamus, the part of the brain that controls involuntary breathing. During CSA, there is no effort by the person’s body to breath; no struggle by respiratory muscles, just stiffness of the body without breathing. Mixed apnea, which is a combination of OSA and CSA, also exists (UMMC 2004, ASAA 2007).
Circadian rhythm sleep, or “normal sleepâ€, consists of a period of time in which the body is at rest to avoid exhaustion (UMMC 2004). During circadian rhythm sleep, one exhibits tidal breathing in which about 700 mL of air is inhaled and filtered through the lungs for oxygen extraction before exhalation. During circadian rhythm sleep, one’s body should comply with average standards such as an average pulse rate between 60 and 80 beats per minute and average resting blood pressure around 120/80 mmHg. The average respiratory rate for a resting adult is between 12 to 18 breaths per minute; however children take about 20 to 30 breaths per minute (UI Health Care 2005). There are two major respiratory gases: oxygen (O2) and carbon dioxide (CO2). The average amount of oxygen in expired breath during tidal breathing is 250 mL of oxygen per breath and for carbon dioxide it is 220 mL of carbon dioxide per breath (George 2007). The average blood pH for a resting adult is 7.35 to 7.45 and red blood cells should be about 33% concentrated with hemoglobin (Hb) (Encyclopedia of Surgery Information 2005).
Proposed Solution
Apneas disturb circadian rhythm sleep and cause the individual to wake up in the night gasping for air. During an apnea, the individual’s pulse, blood pressure, and respiratory rate decrease and they submit to hypoxia (lower than threshold oxygen levels) and hypercapnia (high carbon dioxide levels) (ASAA 2007). There are several risks to people with sleep apnea, among these are higher risks of car accidents due to drowsiness, stroke due to increased blood viscosity, depression due to lack of sleep and low sexual arousal, heart disease, heart attack, heart failure, kidney failure, seizures, headaches, eye disorders, and memory loss. According to doctors at the University of Maryland Medical Center, people with sleep apnea must be diagnosed and treated to help reduce their chances of these terrible risks (Rice et al. 2006).
After diagnosing a patient with OSA, doctors will recommend a series ideas that will help reduce the amount of apneas a person has. There is positional therapy, dieting, exercising, and surgery. The 20% of the American population with OSA has great chances to permanently correct their disorder by simply losing weight, surgically widening their airway, or surgically moving their jaw forward (Rice et al. 2006, ASAA 2007).
The first thing a doctor will say to their newly diagnosed CSA patient is to avoid alcohol and central nervous system depressants because they worsen CSA by relaxing the muscles and impairing the brain. When looking at CSA, there are many solutions available to relieve it, however none of the devices on the market are a permanent cure for this disorder. In order for a device to help the individual, it must first detect an apnea and then trigger a mechanism to induce breathing without waking them (ASAA 2007, Encyclopedia of Surgery Information 2005).
Some currently patented detection devices are adaptive servo-ventilation devices, snorkels, and sleep apnea detection apparatuses. Our company’s proposed detection device for CSA will be a pulse oximeter, which utilizes infrared light shining through one’s finger to measure the Hb concentration on red blood cells.
A pulse oximeter clips onto the patient’s finger and can be kept on for the whole night. It will sense Hb concentration below 33%, which correlates with hypoxia below 75% O2 saturation on red blood cells. When O2 saturation drops below 75%, the photodetector senses an increased amount of infrared light, so the pulse oximeter can trigger the device to induce breathing.
Pulse oximeters are the best detection device because they are comfortable, don’t dry skin out/chaff, are used widely in hospitals, and don’t cause claustrophobia since they are not on the person’s face. For people who move around in their sleep, our company can provide an add-on option to the pulse oximeter that utilizes Bluetooth technology to communicate with the breath induction device rather than a wire. Pulse oximeters are accurate in detecting hypoxia about 80% of the time (AARC 1991, UMMC 2004).
Examples of breath induction devices for CSA patients are continuous positive airway pressure (CPAP), electrical stimulators, and drugs. The most common breath induction device is the CPAP, which delivers a constant flow of air pressure using a nasal mask while the patient is sleeping. Since it is unnecessary to continuously apply pressure to the airway even when the patient is not having an apnea, the R&D department of our company should conduct research to create a positive airway pressure device that administers pressure only when activated by the pulse oximeter (if our company chooses to invest in sleep apnea). CPAP is the most widely used and accepted method for CSA patients because it effectively prevents the patient from having an apnea due to its continuous pressure, thereby providing the patient with smooth respiration throughout the night (Matthews 2003).
On the negative side, the CPAP can cause claustrophobia, dry skin, and discomfort. It is also very large, must be cleaned/maintained meticulously, and cannot be kept in direct sunlight or exposed to excessive amounts of heat. There are several different types of CPAPs like the Auto-CPAP, Smart CPAP, and Goodnight 420E. Our company will use the Auto-CPAP because it is more compact and lightweight than the others, automatically adjusts to altitude changes, and has a display screen that is very user friendly (REMstar 2006).
Our company’s proposed solution consists of a pulse oximeter that detects low Hb/oxygen levels and a CPAP that induces breathing through constant pressure on the airway. This solution works via the feedback loop in figure 5. Although the detection method is wonderful, the breath induction method is already widely in use with many established competitors. Our company should not invest in a sleep apnea device patent because, although the pulse oximeter can cost as low as $80, the CPAP alone is around $800 each at leading companies. A good investment for our company could be not to create a patent, but to have the R&D department create a better CPAP device than leading companies. In conclusion, a patent for a sleep apnea device is not currently a good investment for our company (AARC 1991, Rice 2006, REMstar 2006).
-Amy Shah