Treadmills

Treadmills

Treadmills were first introduced to the world in 1875 as a method of harnessing animal power and by the 1920s; they were used in factories to create make manufacturing more efficient. Finally in 1952, a man by the name of Robert Bruce came up with the idea of having people run/walk on them. He used the treadmill for stress testing by connecting electrodes to the body of the patient which fed signals into an electrocardiograph[1]. This data was used to diagnose heart problems and used in heart and lung research later on. After that, the treadmill began to gain popularity with NASA as well as many other manufacturers. As a result, many new features were added to treadmills like the ability to choose your own speed and heart rate monitoring. And in 1968, Dr. Kenneth Cooper published research on the benefit of aerobic exercise which led to the development of the treadmill industry. From that point on, the treadmill became one of the most widely used biomedical devices anywhere, mostly because of its versatility and availability to people everywhere. The treadmill is effective in combating obesity and other health problems, as long as the treadmill is consistently used.

The treadmill industry has grown significantly in the past decade or two due to the increasingly relevance of obesity and other health problems. In terms of quality and performance, many different brands of treadmills can get the job done. However, some brands get higher average ratings than others. The leading brands include: Smooth, Proform, Nordic Track, and Sole. These brands are known to have solid features and lots of horse power. What does that mean? A serious burn, that’s what. With the recent addition of the incline features, treadmills continue to prove that there is an endless frontier in aerobic exercise.

http://en.wikipedia.org/wiki/Treadmill

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[1] "Treadmill History." Treadmill Life. 2007. 18 July 2008 .

Implantable Artificial Hearts

The implantable artificial heart is a device that many have hoped to produce and use to replace a defective natural heart. The first implantable artificial heart was developed by Domingo Liotta and was implanted by surgeon Denton Cooley in Texas, in 1969. The artificial heart was used for 64 hours by the patient, Haskell Karp, for 64 hours before a transplant heart became available. Although Karp died shortly after the transplant of the natural heart, the artificial heart proved to be viable as a bridge to a transplant heart.
Later, the Jarvik 7 Artificial heart was developed by Dr. Robert Jarvik and was first implanted into a patient in 1982. The Jarvik heart was designed to mimic the natural heart, with two pumps. The longest surviving patient with a permanent Jarvik implantation was William Schroeder, who had the Jarvik heart for 620 days before death. The pumps are air-driven by an external refrigerator-sized box that contains compressed air tanks and vacuum equipment, although there are internal tanks for use during an emergency. While no permanent Jarvik-7 patient survived more than a half-year, the device continues to be used as a bridge unit in selected hospitals.
One of the newest types of the implantable artificial heart is called the AbioCor. It is completely self-contained, with no external device or wires piercing the skin needed. It contains a two-pound pumping unit that contains artificial ventricles that operate using pressure gradients created by the 8000 rpm pump. There is a 20-minute emergency internal battery pack that is used in case of failure of the external, belt-worn battery pack. The battery and power system are able to transmit the power transcutaneously, through the skin, wirelessly. The AbioCor is a major breakthrough in artificial heart development because it will allow for patient mobility without a large external pump.
Sources:
http://en.wikipedia.org/wiki/Artificial_heart
http://texasheart.org/Research/Devices/abiocor.cfm
http://americanhistory.si.edu/exhibitions/small_exhibition.cfm?key=1267&exkey=143&pagekey=216

The Best Types of Pacemakers

Alexis Gorin
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Thursday, July 17, 2008

The Best Types of Pacemakers

In terms of what they for, each type of pacemaker is better suited for certain pathologies, such as how a double-chamber pacemaker is better when one needs to produce an atrial contraction while the triple-chamber pacemaker is better for those who have problems that can eventually lead to heart failure (Olshansky, MD, Hayes, MD). One even better example is the choice between a temporary or permanent pacemaker, which are used depending on what the patient's need is. Therefore, all pacemakers are the best, considering whatever pathology one is trying to fix.

In general though, comparing dual-chamber pacemakers to ventricular pacing, it has been found that dual-chamber is better. According to the Canadian Trial of Physiologic Pacing and the Mode Selection Trial, while they both share similar results, dual-chamber pacemakers do extra by also reducing heart failure symptoms for those who have sinus node dysfunction, chances for pacemaker syndrome, and atrial fibrillation (Hussein, Hennekens, Lamas and Castelnuovo, Stein Pitt, Garside, Payne).

In the market, there are also pacemakers that can allow the heart to beat naturally unless it acts abnormally, which I find better than pacemakers that control the heart through electricity. Unless the heart always acts abnormally, in which case it would probably be easier to use a pacemaker that took total control of the heart, if the heart is allowed to beat on its own, it seems like it would be a waste to use the other type of pacemaker which probably uses more energy. Pacemakers that can adjust to the wearer’s activity are also better than other pacemakers, seeing as that they can allow the wearer to live a life that is there own. (Keeping the Beat: Artificial Pacemakers)

Appendix

Castelnuovo, Stein Pitt, Garside, Payne, E, K, M, R, E. "The effectiveness and cost-effectiveness of dual-chamber pacemakers compared with single-chamber pacemakers for bradycardia due to atrioventricular block or sick sinus syndrome: systematic review and economic evaluation." NCBI. 09 Nov 2005. Department of Health & Human Services. 17 Jul 2008 http://www.ncbi.nlm.nih.gov/pubmed/16266560?ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum.

Hussein, Hennekens, Lamas, SJ, CH, GA. "An update on clinical trials in pacing: is dual chamber pacing better?" NCBI. 19 Jan 2005. Department of Health & Human Services . 17 Jul 2008 http://www.ncbi.nlm.nih.gov/pubmed/14688628?ordinalpos=9&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum.

"Keeping the Beat: Artificial Pacemakers." The Merck Manuals Online Medical Library. 1995-2008. Merck. 17 Jul 2008 .

Olshansky, MD, Hayes, MD, Brian, David L. "Patient information: Pacemakers." UpToDate: For Patients. 2008. UpToDate Patient Preview. 17 Jul 2008 http://www.uptodate.com/patients/content/topic.do?topicKey=hrt_dis/9666.

"Pacemaker." Heart Rhythm Society. Heart Rhythm Society. 17 Jul 2008 .

Pacemakers

Carrie Pottmeyer July 17, 2008

The heart constantly beats about 70 times every minute. These beats are triggered by electrical impulses in the SA node - the hearts natural pacemaker. Once in a while the heart may harmlessly skip a beat. However, a continual irregularity of beating, called arrhythmia, is a serious condition that about 4 million Americans suffer from. Some people are born with arrhythmia while some cases develop due to heart disease and high blood pressure. Self induced factors such as stress, caffeine, smoking, and alcohol can also affect the heart’s beat.

A pacemaker is one solution to this problem. It is a small, battery-powered device that helps regulate the heart beat’s rhythm. Pacemakers can help slow or fast heart rates and blockage in the heart’s electrical system. There are several different types of pacemakers. There are Single-Chamber Pacemakers. In a single-chamber pacemaker, only one wire is placed into either the upper or lower chamber of the heart. In Dual-Chamber Pacemakers wires are coordinated in the atrium and ventricle. This approach closely matches the natural pacing of the heart. Rate-Responsive Pacemakers have sensors that automatically adjust to changes in a person's physical activity.

The different types of pacemakers are used according to the patients’ needs and condition. For example, patients with sick sinus syndrome benefit from the dual chamber pacemaker because they are less likely to develop atrial fibrillation or heart failure in comparison to the single chamber pacemaker. In my opinion, the Dual-Chamber pacemaker would seem to be a better solution than the single because the dual mirrors the natural pacemaker of the heart better than the single. In addition, the rate responsive would be beneficial to active lifestyles. The best pacemaker seems to be a combination of the dual chamber and the rate responsive pacemaker.

Heart Rhythm Society
http://www.hrspatients.org/patients/treatments/pacemakers.asp

Texas Heart Institute
http://texasheart.org/HIC/Topics/Cond/Arrhythmia.cfm

Pacemakers

A pacemaker is a medical device that fixes hearts that aren't beating properly. When the pacemaker senses irregular beating of the heart, it will fire a short, low voltage pulse to stimulate beating. There are also many different types of pacemakers in the market. Demand pacemakers are pacemakers that monitor the heart's natural electrical activity and discharge only when the heart's own rate is too slow or the heart misses a beat. Fixed-rate pacemakers discharge impulses at a single, steady rate, regardless of the heart's own electrical activity. Rate-responsive pacemakers are designed to raise or lower the pacing rate to help meet the body's needs during physical activity or rest. Pacemakers may also be single, dual or triple-chambered pacemakers. Single-chambered pacemakers generally only have to carry impulses to and from either the right atrium to the right ventricle. A dual-chamber pacemaker usually only has two leads, one to the right atrium and one to the right ventricle, both of which can monitor and carry impulses to one or both chambers. This type of pacemaker mimics the natural function of the heart. Triple-chambered pacemakers improve the heart's blood flow. There are temporary and permanent pacemakers that can be either be implanted or not. It really depends on which pacemaker is best suited to your heart's needs, but I feel that the rate-responsive pacemakers are best. They do not exert unnecessary electrical impulses like the fixed-rate pacemakers do. They can also adjust to different needs of the body during different strenous activities.

TAH: total artificial heart

Here is an interesting article from Scientific American about the total artificial heart: http://www.sciam.com/article.cfm?id=not-just-a-pump

It follows the development of the TAH and what obstacles had to be overcome as well as what lies ahead. The article discusses both the Jarvik and AbioCor hearts as well as Barney Clark who was kept alive on an artificial heart for 112 days in 1982 (this artificial heart was the size of a refrigerator so if you compare that to the devices that were shown in class today, you can see how far technology has come).

Anatomy Videos

For those of you interested in human anatomy to supplement the physiology material you are receiving during lecture, you can watch gross anatomy dissections at: http://www.anatomy.wisc.edu/courses/gross/

LVADs/heart transplantation

For those of you interested in LVADs and heart transplantation, last week's episode of HOPKINS featured a young Bermudan patient who had an LVAD and received a donor heart. They show the process of procuring the heart with the surgeons flying to the donor to harvest the organ then coming back for the transplant. Parts of the operation to remove the LVAD are also shown in the episode. You can watch the video at abc.com (http://abc.go.com/player/?channel=117113).