About 7 years ago, I saw a very interesting show on NOVA. It was about a Brazilian heart surgeon who had theorized that people with damaged (enlarged) hearts could be helped by cutting away the excess heart tissue.
Has this guy been proven correct?
Disclaimer: IANA cardiologist.
Transcript of the show.
http://www.pbs.org/wgbh/nova/transcripts/2409heart.html
CNN.com article.
http://www.cnn.com/HEALTH/9703/18/heart.remodel/
In 1997 Dr. Batista proposed surgically removing a portion of the heart muscle tissue (a “partial left ventriculectomy”) to help idiopathic dilated cardiomyopathy.
In 1998 an independent study from Yugoslavia was published that showed it worked.
In 1999 Batista’s own data from 1995 through 1998 was reviewed. Conclusion: it works.
http://www.charite.de/ch/hzchir/publ/publ99/abst9904.html
And nowadays it looks like it’s one of several mainstream surgical options.
http://www.nice.org.uk/cms/ip/ipcat.aspx?o=56737
http://health.allrefer.com/health/dilated-cardiomyopathy-treatment.html
So, props to Dr. Batista.
And props to DDG for her excellent research.
And I am not a cardiologist either. But I have sent some of my patients to be evaluated for cardiac surgeons who do this sort of thing. Or who know other cardiac surgeons who do this sort of thing.
This sort of surgery can be life-saving. But it is extreme, and at present is mainly used for patients with severe congestive heart failure which doesn’t respond to other therapies.
There are a variety of surgical options, from debulking (removing) severely overdeveloped heart muscle which no longer functions properly as a pump because of its own excess growth, to removing excessively dilated muscle which has grown too think to contract properly, to adding muscle from other places in the patient’s body (generally back or abdomen) to the patient’s own heart, and inducing the new muscle to beat in time with the heart, and add to the pumping function.
As you can surmise, this is a major operation. And if diet, weight loss, and appropriate medications can keep the heart failure in check, they are much preferred as a treatment over radical surgery.
But it is nice to have more options.
I have heard many a lecture about this technique, since a good percentage of people in my program (MD/PhD combined degree) do bioengineering, and they love to talk about this stuff. Forgive me if I get the details wrong; I am not a cardiologist nor am I a doctor nor am I an engineer. And it has been 4 years since I have been in clinics.
When the heart muscle has decreased efficiency (either through part of it dying in a heart attack or ischemic heart disease or dilated cardiomyopathy), there are triggers which remodel the heart muscle. The most maladaptive is ventricular dilatation – the ventricles get larger so they can hold more blood as the heart relaxes.
One of the triggers for remodeling is stretch receptors in the heart muscle which detect wall stress. Among other things, these cause release of atrial natiuretic peptide (vasopressin), which causes more reabsoption of sodium in the kidneys and therefore more fluid retention in the body. The body tries to maintain blood pressure with a failing heart by retaining more fluid in the circulatory system. This will eventually lead to congestive heart failure.
Wall stress can be estimated using the Law of LaPlace: Tension = Pr/2h where P = ventricular pressure and r = radius and h = wall thickness. Decreasing wall thickness (by infarct) increases tension. Increased pressure and dilation of the ventricles also increase tension. So ventricular dilation is not only primarily maladaptive, but it starts a vicious cycle, as it causes wall stress to increase.
All of these surgeries try to decrease wall stress through manipulating these variables. Ventriculectomies take out dead muscle to reduce radius, thus reducing tension. Other interesting things that are being tried are little socks that are put around the heart to restrict heart expansion (and thus decrease radius and increase wall thickness). Another thing is to change the shape of the heart from a spheroid-type shape to a more oblong shape through the use of something called a CardioClasp. For extreme cases, one can reduce wall stress by providing a ventricular assist device (VAD), which is an external pump that helps the heart work. This lets the heart muscle recover under conditions where it is not overloaded.
First-line intervention for congestive heart failure now also includes vasopressin blockers to prevent the vicious cycle. Or at least so I’ve heard. It’s been a while. Perhaps Qagdop or another Real Doctor can correct me.
You are just the guy I want to talk to! A related question: engineers who have sought to build an effective artificial heart have always tried to emulate that natural pumping action of the heart…however, wouldn’t a rotary-type pump be more efficient and more reliable? I heard that a rotary-pump heart was tried-is there any reason why such a prosthetic heart wouln’t work as well? Of corse, you wouldn’t have a heartbeat, but you would be alive! 
It’s my understanding that bypass uses a rotary type of pump. I’m not a doctor, but have been a patient on bypass 5 times. Each time, it was explained to me that time on bypass needed to be kept to an absolute minimum, because in the absence of an actual pulse, organs begin to deteriorate very quickly. My understanding is there is something in the pulsating motion of the blood, with briefly alternating high and low pressures, that the tissues are dependent on.
Most blood pumps now do use rotary pumps – the VADs (ventricular assist devices) that I mentioned above use a centrifugal style (vortex) rotor and pump, and most heart-lung bypass machines use roller pumps or the centrifugal style pumps. The DeBakey heart uses a vortex-style pump as well. Here are some pictures:
Thoratec ventricular assist system: http://www.thoratec.com/ventricular-assist-device/heartmate_lvas.htm
MicroMed DeBakey heart: Hints For Creating A Strong Research Paper
The issue to overcome, IIRC, is shear strain on the red blood cells. Roller style pumps have quite a high shear strain, and long term use can lead to hemolysis and the complications that arise from that (mostly kidney issues). This is apparently lower in centrifugal pumps and contractile pumps. Another issue is actual contact with the blood. Roller pumps don’t touch blood, and can be reused easily (which makes them ideal for heart surgeries). Centrifugal and contractile pumps do – this can cause immune reaction with the pump machinery and a number of other associated bad things.
IANA expert by any means. I can ask around if you would like. I am not sure about the necessity of a pulse – IIRC pulse pressure is quite low on all of these assist devices and extracorporeal pumps. The LVAD can be used for months. But again, I’m not sure and so SuperNelson could be right.
Or I could be full of beans. I had my mind on other things at the time, not the least of which was morphine, and I’m the first to admit that the effects of the phenobarb and profound hypothermia made me a little loopy for quite a while. Your explanation of hemolysis affecting the kidneys does fit with my recollection of the risks.