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

A 65 year old man with end-stage cardiomyopathy and severe hypertension desperately needed a heart. After September 11, 2001, Castelio Campos received news that one of the victims of 9/11 had a heart that was a match for him.  He eagerly arrived and the hospital, was anesthetized, and then awoke before the surgery had been completed.  The nurses informed him that unfortunately, the heart was not a perfect match.  Mr. Campos was also told that he would have to wait in the hospital until they found a heart for him.  After a few months, he was highly ischemic and had advanced pulmonary hypertension, so surgeons at the University of Miami strove to find a way to help him.
The surgeons decided to preform a heterotopic heart transplant in which they left his native (N) heart in and went forward with the transplant of a not-so-perfect donor heart. They placed the allopathic donor heart (D) right next to his native heart (as shown in the two figures below). As can be seen on the EKG below, this patient is living with two QRS complexes on different axes.  Thanks to Mr. Campos’ successful surgery, there are now about 100 people in the world living with two hearts.

In the figure above, visual A shows the patient’s EKG results and differing QRS complexes can be viewed by at the arrows D (donor heart) and N (native heart). Visual B shows a front view of the patient in which a cardiac defibrillator is treating the native heart. Visual C shows the top view and demonstrates the close proximity of the two hearts and the amount of space they occupy in the chest cavity.

Information obtained from the American Heart Association and the New England Journal of Medicine.

-Amy

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