New Imaging Techniques to Improve Diagnosis of Cardiovascular Disease

This picture is part of vibrational photoacoustic image that shows the plaque in a wall of the artery(Purdue University)

Cardiovascular disease is the one of the leading causes of death in the United States; it affects all people equally regardless of age, gender, or ethnicities. The research for this disease is vast and the treatment is vital. However, the diagnosis is equally important. This new imaging technology helps in diagnosing cardiovascular disease. It utilizes Vibrational Photoacoustic or VPA microscopy with the help of ultrasound signals where molecules are exposed to a fast pulsing (nanosecond) laser in the IR range of the spectrum. The vibrations generated by the laser does not produce any effect in the blood, in turn, these vibrations create heat and that generates "pressure waves that can be picked up by a device called the transducer". Although there are imaging techniques that exist to provide molecular information about a disorder, this type of method enables to penetrate deep into the tissue to create a three dimensional model of the plaque and moreover, "eliminates the tissue scattering problems". This precise character of the imaging technique aids in locating and revealing "the C-H bonds found in lipids that cause the formation of plaque in cardiovascular disease". Even though, it is mainly used for diagnosing heart disease, recent results proved that in fact, VPA can be a vital tool for diagnosing diseases such as diabetes or other lipid based disorders of central nervous system or also to study the role of collagen in scar formation. Currently, biomedical engineers at Purdue university are working on quantifying this technique by miniaturizing the system itself to use it as an endovascular procedure that can be inserted into the blood vessels to know the “exact nature of the plaque formation”.

http://www.sciencedaily.com/releases/2011/06/110609173720.htm
http://www.purdue.edu/newsroom/research/2011/110609ChengVascular.html
http://www.cdc.gov/heartdisease/facts.htm

First Successful Transplant of Pulseless Artificial Heart

A pulseless artificial heart was successfully implanted into a Houston man, 55, last month. The man suffered from a rare buildup of amyloid proteins which impaired the function of his heart so severely that he was given roughly one more day to live at the time of transplant.

The device was engineering by heart specialists, surgeons, and inventors Dr. Bud Frazier and Dr. Billy Cohn of Texas Heart Institute. It consists of two continuous flow pumps (named Heartmate II) strapped together and powered by an external battery pack. "Continuous flow" means that
the patient's blood flow is nonpulsatile; the beating of the heart is no longer mimicked and the patient has no pulse. Interestingly, the device required nonconventional methods be used to monitor the patient's blood pressure. Because of the nonpulsatile flow, his blood pressure is a constant value and cannot be determined using a cuff, but must be measured using Doppler ultrasound.

Frazier and Cohn began building a prototype of the device more than 5 years ago, using supplies purchased at local stores like Home Depot. They promote continuous flow pumps because of their simplicity and reduced size and noise. Fewer moving parts are used in continuous flow pumps, which makes them potentially much longer-lasting as there is less friction between parts and thus less wear-and-tear between them. Additionally, continuous flow pumps automatically adjust output based on demand.

I looked up this article after hearing about this in a meeting with Texas Heart Institute, and found it fascinating as well as applicable to our semester project: a pediatric artificial heart. I thought it was interesting that it could finally be used as the man's condition had deteriorated so severely; it seems that finding patients on which to test new devices (particularly unorthodox ones) is a constant dilemma. The device is obviously in its younger stages and needs continued testing and development, but it would be interesting to see how this man fares.

http://www.texasmedicalcenter.org/root/en/TMCServices/News/2011/04-01/Houston+Man+First+in+World+to+be+Successfully+Implanted+with+Pulseless+Artificial+Heart.htm
April 21, 2011

Non-viral Gene Delivery with Stents for the Treatment of Restenosis

Scientists and engineers at Northeastern University and the University of Pittsburgh collaboratively designed and performed an animal trial to demonstrate how gene eluting stents can be made to alter the gene expression of the tissues they contact in order to treat or prevent restenosis of the artery. In this study, the researchers used liposome structures, adhered to the stent in a gelatine mixture, to deliver a gene coding for human endothelial nirtic oxide synthase to the tissue around the stent. Nitric oxide is useful in the treatment and prevention of restenosis because it both discourages smooth muscle growth, which is a cause of arteriosclerosis, and promotes healthy endothelial growth to cover the damaged areas of the artery. A gene that produces this enzyme that catalyses the production of nitric oxide provides an opportunity to help the body essentially heal itself. Another notable accomplishment of the study is that they were able to introduce the genes without the need for a virus vector, which can have a high cytotoxicity and is unlikely to be used in a clinical setting.

This study could have a huge impact upon future treatment of cardiovascular disease. Today, stenting is done routinely, and restenosis is a very common problem, sometimes requiring additional surgery and other therapies. As this problem has become obvious, drug eluting stents have become the weapon of choice against restenosis. Drug eluting stents, however, are imprecise (their drugs affect more than the immediate area), and the drugs they carry could be improved upon. Using a form of gene therapy to temporarily induce the cells in the damaged area to produce nitric oxide would be a very attractive therapy either alone or in tandem with other therapies to treat restenosis, especially if it could be done without a virus vector.

This article is highly interesting because of its implications in the treatment of one of the most common causes of death in the developed world: cardio vascular disease. It is interesting how the researchers were able to think a little bit outside the box in treating this common disease.

http://www.biomedical-engineering-online.com/content/9/1/56