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Biotech

Living Without a Pulse 759

Posted by michael from the cold-blooded dept.
SteamyMobile writes "Can you live without a pulse? Yes, now you can. The reason why we have a pulse is because it's hard for evolution to result in turbines or continuously spinning things. The next generation of artificial hearts may have no pulse. They also have no bearings, so they should last much longer than previous attempts. In fact, engineers don't give a predicted lifespan on these models. How would your life be different without a pulse?"
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Living Without a Pulse More

Living Without a Pulse

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  • Hmm (Score:5, Funny)

    by grub ( 11606 ) <slashdot@grub.net> on Friday July 30, 2004 @08:55AM (#9842571) Homepage Journal

    How would your life be different without a pulse?

    I would have had much more in common with my ex-wife.

    • Re:Hmm (ex wife, but seriously...) (Score:5, Insightful)

      by kiatoa ( 66945 ) on Friday July 30, 2004 @09:04AM (#9842675) Homepage
      I'm sure someone will be adding their favorite politician to this thread but seriously - I'd put money that there will be some consequences to not having a pulse. Valves will not get the exercise they need or something. N million years of evolution (or 7 days of design if that is what you buy into) means that there are probably lots of subtle interdepenancies of a pulsating blood supply. Of course some of the consequences might well be good...

      • Re:Hmm (ex wife, but seriously...) (Score:4, Interesting)

        by EpsCylonB ( 307640 ) <eps&epscylonb,com> on Friday July 30, 2004 @09:26AM (#9842915) Homepage
        I had a very similar reaction, IANAHS (I am not a Heart Surgeon) but in the article it says...

        it only has one moving part, a spinning impeller that drives a continuous stream of blood.

        Surely the human body is not designed for a continuous stream of blood ?.

        Saying that I am sure that this has all been researched thorougly to get to this stage and my limited medical knowledge probably isn't very useful.

        • mdiarmspafpothama (Score:5, Insightful)

          by TamMan2000 ( 578899 ) on Friday July 30, 2004 @09:41AM (#9843048) Journal
          I had a very similar reaction, IANAHS (I am not a Heart Surgeon) but in the article it says...


          it only has one moving part, a spinning impeller that drives a continuous stream of blood.

          Surely the human body is not designed for a continuous stream of blood ?.

          Saying that I am sure that this has all been researched thorougly to get to this stage and my limited medical knowledge probably isn't very useful.


          mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate) and he agrees with you.

          I told him about a woman in england that had an earlier version of one of these for several days while waiting for a real (human) heart (this was a few years ago). His imediate reaction was that pulsitile flow probably slows the build up of plaques in the arteries, and that people without a pulse would, IHNSHO (in his not so humble opinion), be more likely to experience blockages.

          Of coarse that was just his gut reaction and he has not researched the topic...

          • Re:mdiarmspafpothama (Score:5, Interesting)

            by GPSguy ( 62002 ) on Friday July 30, 2004 @10:14AM (#9843370) Homepage
            Well, having actually spent some time doing partial and total artificial heart research, including about 6 years with the earlier LVAD (pulsatile) technology, I'm of two minds about this.

            1. I don't believe we'll see increased atherosclerotic plaque deposition due to non-pulsatile flow. I'm currently subscribing to the theory that plaque is related in chronic bacterial infection of the vascular intima.
            2. There was some evidence, but poorly followud up in the past, that renal function was on the short list of critical elements requiring pulsatile flow. One reason for inadequate continuing studies was that the problems with on-pump anticoagulation, infection and anesthesia tended to introduce enough variables to make isolation of the pulse issue too obscure.
            3. There have been a number of reports in the past, some as long as 15 years ago, of surgeons using the Biomedicus BioPump, a similar design, for extracorporeal bridging support to transplantation, or similar to the anecdote below, to place the heart at rest to allow its recovery. I'm aware of many cases (I participated in at least 10) of multiple-day attempts, and at least 2 or 3 trials of several weeks. Realize that the patients were already moribund, so supporting them in bridging, awaiting a suitable donor, was their last and sole chance for survival. And, no, most of them didn't survive to transplant.

            I'm intrigued. I'm out of the business now, but I'm convinced that we're overdue for some real breakthrough to make implantable artificial devices for continuous perfusion a viable alternative to transplantation with the limited pool of donors.

            • Re:lack of pulsatile flow and coronary vessles (Score:5, Interesting)

              by henryhbk ( 645948 ) on Friday July 30, 2004 @11:19AM (#9843981) Homepage
              I am an internist, but we deal a lot with cardiac surgery patients.

              A major problem with continous flow would seem to be the diastolic part of the cardiac cycle (when the heart is refilling) is critical for back-flow from the body (arteries do not have valves) into the coronary artieres (the arteries that feed the heart). The aorta (main artery from the heart to the body) is elastic, so a large bolus (fluid surge) of blood is ejected into the aorta, stretching the aorta during systole (contraction of the heart). When the heart then relaxes (diastole) the stretched aorta recoils, and squeezes blood both forward and backwards. The heart has an output check valve at the aorta (aortic valve) which prevents it from completely flowing back; however a small takeoff (the sinus of valsalva) allows the blood to surge into the coronary arteries, and since the heart is relaxed, flow all the way to the muscle of the heart. I don't know if someone has looked into coronary blood flow during these continous pumps, but it might be useful to see, since these hearts are in bad enough shape without becoming ischemic (oxygen starved)

              • Re:lack of pulsatile flow and coronary vessles (Score:4, Insightful)

                by afidel ( 530433 ) on Friday July 30, 2004 @11:42AM (#9844238)
                Uh, isn't the entire point of these pumps to REPLACE the damaged heart? I mean if you have a low maintenance pump with little chance of failure why are you relying at all on the failing/failed natural heart?

              • Re:lack of pulsatile flow and coronary vessles (Score:5, Interesting)

                by cellocgw ( 617879 ) <cellocgw.gmail@com> on Friday July 30, 2004 @12:14PM (#9844639) Journal
                Blood will always flow if there's pressure behind it (doh). I'd expect, based more on physics than any experience in cardiology, that a continuous flow at maybe 100mm (well below common systole) would work just fine without overstressing any part of the system.
                But if future studies were to show that a pulsing system really does something useful, it shouldn't be too hard to put a controller chip that has the impeller spin up and spin down at some reasonable rate.
                BTW, just because it's different from nature doesn't mean it's harmful. For example, it may have taken 50 years (largely due to politics) but it's now considered medically safe for women to take continuous contraceptives and go without menstrual cycles for all or most of the year.
            • I'd appreciate a link to that... I've been doing this for a long time, and I've never thought that belief was widely held. I've heard of theoretical links between C. pneumoniae, but that's about it (of course, C. pneumoniae has been theoretically linked to all kinds of things, including Chronic Fatigue Syndrome, among others).

              I'd say the classical risk factors for heart disease still hold; smoking, hypertension, diabetes, the bad gene (usually a triglyceride or cholesterol metabolism problem), etc. This
              • My dad has to take some pretty hefty doses of antibiotics before any dental work. Apparently he has some minor heart valve issues and the bacteria from his mouth can get into the blood stream when the dentist is doing his thing and cause havoc. Does this have anythign to do with what you are talking about? Is the dentist just covering his butt?

                • Re:Chronic bacterial infection? (Score:5, Informative)

                  by The Tyro ( 247333 ) on Friday July 30, 2004 @01:12PM (#9845410)
                  No. Your dentist is actually doing the right thing.

                  Your dad has a valve problem in his heart, and dental work does cause a transient bacteremia (bacteria being released into the bloodstream). Most of the time your immune system will clear out those bacteria, no problem... most of the time.

                  If you have a damaged heart valve, those bacteria can infect the valve, leading to a condition called Bacterial Endocarditis. The bacteria grow on the valve, and can destroy that valve, as well as throwing infected bits downstream in your circulation, leading to brain abscesses, kidney and lung infections, and general sepsis.

                  Endocarditis is a nasty, nasty condition... probably most of the cases I've seen were IV drug users. It's a hell of a life; some of those folks will shoot up anything they can find, regardless of what's in it (ie. foreign material loaded with bacteria). Also, when they are re-using needles, the needles will eventually dull, and sometimes barb (painful!). To detect a barb, addicts will sometimes lick the needle tip, then shoot up if no barb is felt with the tongue... you can see where I'm going with this. The human mouth is only slightly less dirty than the human anus... they end up injecting tons of bacteria, and develop Endocarditis. To make matters worse, they never go to the doctor, except when they try to scam more narcotics, or inadvertantly overdose. By the time they do show up, their valves are shot, and they're almost dead. If they survive, they end up needed open-heart surgery and valve replacement.

                  Anyway, that's probably more than you wanted to know... but as far as dental procedures go, the antibiotics your dad takes are effective in preventing Endocarditis. He'd be well-advised to keep taking them as prescribed.

                  I don't think the original poster was referring to Endocarditis though... I'm fairly sure he was referring generally to Atherosclerotic Disease.

          • Re:mdiarmspafpothama (Score:5, Funny)

            by Baseclass ( 785652 ) on Friday July 30, 2004 @10:15AM (#9843378)
            mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate)

            You don't have to spell it out, we're all familiar with that acronym.

            • mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate)

              You don't have to spell it out, we're all familiar with that acronym.

              Well now I feel like an idiot for going "em-dia-rmspaf-pothama... what the hell is that?" *click shortcut to open dictionary.com in new tab*

          • Re:mdiarmspafpothama (Score:3, Interesting)

            by dougmc ( 70836 )

            His imediate reaction was that pulsitile flow probably slows the build up of plaques in the arteries, and that people without a pulse would, IHNSHO (in his not so humble opinion), be more likely to experience blockages.

            Perhaps, though people should remeber that these artificial hearts are meant for people in extremely dire straights. Their life expectancy, even with the artificial heart, probably isn't long enough to allow the build up of plaques.

            I noticed that the pump still has external wires for

      • You are absolutely correct. If you look at the internal surface of a major vein you will notice that it it is uneven. It does not allow blood to flow back and this works properly only with a pulse flow. It will not work properly with a constant flow. So people who rely entirely on a device like this will be prone to various vein problems - varicose veins, cirrose like vena portalis deformities, etc. So devices like this cannot replace a heart 100%. At the same time they may be enough to provide assistance f

        • Re:Hmm (ex wife, but seriously...) (Score:5, Interesting)

          by D3 ( 31029 ) <daviddhenningNO@SPAMgmail.com> on Friday July 30, 2004 @09:40AM (#9843044) Journal
          Actually, I read a Reader's Digest article about a similar pump a couple years ago. Some young girl in England had a viral heart infection and would have required a transplant. Instead, they stopped her heartbeat and implanted a constant pump like this. The doctors were all concerned about the effects of not having a pulse, not having 2 bounces for blood pressure measurements.

          She lived quite well with the device and the stopping of her heart actually let the heart muscle repair itself. It turned out that resting the muscle was very good for it. She was eventually taken off the device and her heart restarted.

          So no, there are not the adverse effects doctors had theorized about.

          • Re:Hmm (ex wife, but seriously...) (Score:5, Interesting)

            by GPSguy ( 62002 ) on Friday July 30, 2004 @10:21AM (#9843436) Homepage
            When you place the heart at rest, you remove the load it sees, and use an artificial pump to do the work.

            You don't stop the heart. Even today, with cardioplegic solutions significantly advanced, supplemented with NAD-compounds and amino acids, stopping the heart bears the significant risk that you can't get it restarted again.

            Cardioplegia for cardiac surgery involves infusing a potassium-rich solution into the coronary arteries, which stops the heart in diastole. Further, the solution is cold, and the heart is bathed in an iced saline slush to cool it further and diminish its metabolic requirements. At this point, the heart is *NOT* getting a blood rich perfusion (barring the use of blood-based cadioplegia, which I'm still not sure is as good an idea as some others think) medium.

            If you were to start reperfusing the arrested heart with blood, with a normal electrolyte composition, the extra potassium would be washed out, the heart would rewarm, and if it has sufficient energy stores, and a sufficiently normal physiology, it would begin to contract again.

            So: To put the heart at rest, you unload it, keep the blood chemistry as normal as possible, maintain good nutrition status (parenteral alementation), and see if the heart muscle recovers.
        • If you look at the internal surface of a major vein you will notice that it it is uneven. It does not allow blood to flow back and this works properly only with a pulse flow. It will not work properly with a constant flow.

          But a flowback prevention device is only needed because of the pulsed flow. Without flowback prevention, blood could never reach the head as it would keep running back down the arteries as the heart cycled. As long as a continuous flow is of sufficient pressure, this problem is eliminate

        • Re:Hmm (ex wife, but seriously...) (Score:5, Informative)

          by Anonymous Coward on Friday July 30, 2004 @10:00AM (#9843251)
          Only arteries have a pulse. The blood flow is as follows: heart -> arteries -> capillaries -> veins -> heart. By the time the blood gets thru the capillaries to the veins the blood pressure is vastly reduced and the pulsatile flow generated by the heart is not felt in the veins. Hence veins do not have a pulse. The valves in the veins have nothing to do with the pulsatile flow of the heart and hence a constant flow heart will not affect the functioning of the veins in any way. Venous problems like varicose veins, cirrose like vena portalis deformities are not related to how the heart pumps.
      • The thing about a pulse is the blood vessel valves need only open at the peak pressure of the pulse. The rest of the time the blood pressure can be quite low. On average the blood will still flow the right way.

        Whereas for a pulseless heart the blood pressure has to be at the peak continuously.
        There are also other issues to do with general plumbing - I read somewhere that heart surgeons have found putting a slight twist in a bypass vein makes it less likely to clog up. Theory is that it causes the blood to

  • He's Dead, Jim. (Score:5, Funny)

    by mfh ( 56 ) on Friday July 30, 2004 @08:55AM (#9842573) Homepage Journal
    FTA: "The pump also has a curious side effect: people implanted with the device have no pulse."

    They had better put an obvious port on it so paramedics know it's there before sending voltage through.

    I can see the first really drunk guy with one of these taking a nap on the beach:

    "ZZzzzzzzZZZZzzzzzZZ"

    "Sir!"

    "Oh my GOD! He's Dead, Jim!!!"

    "He's got no pulse! Call an ambulance!"

    (ambulance arrives, 10min later)

    "This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal!"

    "CLEAR!!!!!!!!!!!" "ZZZZAPP!!!!" /dies
    • This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal
      If they are so drunk they don't react in any noticable way to 10 minutes of CPR then they need the ambulance (probably just to cart of the body.)

    • Re:He's Dead, Jim. (Score:5, Informative)

      by akiaki007 ( 148804 ) <aa316@nyWELTYu.edu minus author> on Friday July 30, 2004 @09:02AM (#9842650)
      (ambulance arrives, 10min later)

      "This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal!"

      While ths scenario is pretty funny...most CPR certified professionals check for breathing, not a pulse. And if they didn't, then they shouldn't be certified. Yes, they also check for a pulse, but not before they check for breathing. Depending on the body fat on a person, the pulse isn't always easily detected.

      • Re:He's Dead, Jim. (Score:5, Informative)

        by sql*kitten ( 1359 ) * on Friday July 30, 2004 @09:11AM (#9842747)
        most CPR certified professionals check for breathing, not a pulse.

        Yup, ABC, Airway, Breathing, Circulation. One of the fist things they teach in First Aid class. You can have a hearbeat while not breathing, but you can't breathe without a heartbeat.

        • Re:He's Dead, Jim. (Score:4, Informative)

          by The Tyro ( 247333 ) on Friday July 30, 2004 @10:04AM (#9843289)
          They expand on the acronym in a couple of scenarios.

          ATLS (Advanced Trauma Life Support, a program by the American College of Surgeons) expands that to ABCDE: Airway, Breathing, Circulation, Deficits in neurologic function, and Exposure (remove/cut off all clothing... easier to find injuries and wounds that way).

          Also, the "C" in the old "ABC" acronym is also supposed to stand for Cerebral protection in addition to circulation. I've also heard CPR termed "cerebral pulmonary resuscitation." That's probably a fair substitution, since your main goal in CPR is to protect the brain by creating a low-flow rather than a zero-flow state (contrary to what some folks think, CPR doesn't restart the heart from a V-fib/V-tach arrest... generally only electricity can do that).

          Once your brain's dead, you're dead... even if your heart, lungs, kidneys, etc are all working normally. Those folks become organ donors, or should...

          Let me put in a plug here... PLEASE CONSIDER DONATING YOUR ORGANS. Please... talk to your family about it, get it on your driver's license or living will. Lots of people need organs, and if you don't need yours anymore (and you have no deep religious/philosophical objection), why not donate them? Just a thought...

        • You can have a heartbeat while not breathing, but you can't breathe without a heartbeat.

          Yes you can have breathing without a pulse. It is called agonal respiration [cityofhinesville.org].

      • so what you're saying (Score:4, Funny)

        by BitterAndDrunk ( 799378 ) on Friday July 30, 2004 @09:41AM (#9843053) Homepage Journal
        "Depending on the body fat on a person, the pulse isn't always easily detected."

        So basically most Americans effectively have no pulse already? I swear, we're always ahead of the curve.

    • But seriously... (Score:4, Informative)

      by The Tyro ( 247333 ) on Friday July 30, 2004 @09:30AM (#9842951)
      the procedure is actually to assess them first... something along the line of shaking them and asking "Annie! Annie! Are you OK?"

      If they answer "yes," you're done.

      I realize you were only joking, but the entire clinical picture needs to be taken into account.

      My favorite EMS call is the patient with a minor head injury who is rushed in with a "blown pupil." When you go see the patient, they're awake and alert, not vomiting, not somnolent, etc. It's usually someone who's new, and doesn't understand the pathophysiology behind Uncal Herniation and 3rd nerve compression.

      Back to the topic at hand... I wonder if the lack (or blunting) of the systolic peak and diastolic trough in the blood pressure would lead to any physiologic problems? According to the article, the device is actually a Left Ventricular Assist Device (the ole' intra-aortic balloon pump is the classic example of such a device). It steals blood from the left ventricle and steadily pumps it into the aorta... but I wonder if it has any effect on the coronary arteries?

      The coronary arteries mainly fill during diastole, when the aortic valve closes and blood floods the coronary sinuses on the aortic side of said valve... since this device essentially "steals" blood from the left ventricle and injects it somewhere downstream, I wonder if the coronaries get the same filling? (I suppose it's a question of where you place the downstream catheter.) It might not make a difference if you have clean coronaries, but if you've got a Left-main stenosis, it could be bad to drop that filling pressure...

      In a perfect hydraulic system, it wouldn't matter, since pressure injected in one location would increase pressure in all locations... but arteries have compliance, and they can flex.

      Interesting device... it'd be nice to know some more details.
    • "CLEAR!!!!!!!!!!!" "ZZZZAPP!!!!" /dies

      Why would he die?
      Running electricity through where his heart used to be would not affect the insulated pump.

      However, there should be a label: "Normal blood pressure 90 psi. Check oil every two years. Turn off this switch before autopsy or burial. Press red button before vigorous exercise."

    • Actually I think it would go like this:

      "ZZzzzzzzZZZZzzzzzZZ"

      "Sir!"

      Checks pulse "He has no pulse, start CPR."

      "Get the hell off me."

      "AAAAAAAA".

  • What will Nurses do... (Score:3, Funny)

    by JagRoth ( 115052 ) on Friday July 30, 2004 @08:56AM (#9842585)
    ... at the Doctors office without being able to take our pulse while they stall until there is a doctor available to see us?

    • Re:What will Nurses do... (Score:5, Funny)

      by Bob McCown ( 8411 ) on Friday July 30, 2004 @09:00AM (#9842634)
      I guess they'll just put a timing light on my, er, finger, and check my RPM.
    • ... at the Doctors office without being able to take our pulse while they stall until there is a doctor available to see us?
      You've never used the UK's National Health Service.
      The nurses don't take your pulse while you wait for a doctor in our hospitals - after 4 hours of pulse taking, they would probably not have learnt a great deal more.
      And that's the emergancy patients.
    • Well, at least if it's a cute nurse, she wouldn't be able to tell you're imagining her in her undies by your speeding pulse.

      On the other hand, "My net blood flow through my impeller turbine surges when I think of you" just doesn't really sound all that romantic.

  • Nature's solution is best in at least a few ways. (Score:5, Interesting)

    by etymxris ( 121288 ) * on Friday July 30, 2004 @08:57AM (#9842599)
    ...the VentrAssist is less likely to damage red blood cells because it moves the blood more slowly with a bigger impeller.
    That's why you haven't seen more propellor based solutions--they tend to chop up the cells. Propellors work great on something you don't mind mincing up, such as air for planes, water for boats, and ice for that delicious smoothie. But I'd be hesitant to send my red blood cells through a propellor. I know they're talking about impellers and not propellors, but I see little difference in damage capacity.

    • Well yeah, but this is for when natures's solution fails. Kidneys and bone marrow solve the blood cell damage problem. :-)

      I'm wondering about the little one-way valves throughout the body which aid the pulse. Does such a system damage or suffocate those valves?

      Aren't there other systems in the body which depend on the pulse? Could the move to a pulseless heart make a later transplant less likely to be successful?

      • Re:Nature's solution is best in at least a few way (Score:5, Interesting)

        by sql*kitten ( 1359 ) * on Friday July 30, 2004 @09:32AM (#9842971)
        I'm wondering about the little one-way valves throughout the body which aid the pulse. Does such a system damage or suffocate those valves?

        Also, the heart isn't the only pump in the body - the muscles in your legs help return blood to the heart when you run. That why if you run then stop abruptly you feel faint, because suddenly the load on your heart has suddenly increased and it needs to ramp up to pump blood all the way up to your head at a usable pressure (which is one reason you should warm down properly after exercising). How would the impeller interact with "pulses" from the legs?

  • variable speed (Score:5, Insightful)

    by tverbeek ( 457094 ) on Friday July 30, 2004 @08:58AM (#9842602) Homepage
    How would your life be different without a pulse?

    I wouldn't be able to tell how hard I'm exercising. Which brings up the point that these turbines are going to have to be variable speed if they're going to accommodate humans' varying oxygen needs.

    • Re:variable speed (Score:4, Insightful)

      by Tassach ( 137772 ) on Friday July 30, 2004 @09:06AM (#9842695)
      Turbines are generally happiest when running at a constant speed. However, it's not necessary to vary the turbine's speed to duplicate the heart's action -- what you really need to vary is the net flow rate. A variable net flow rate can be achieved even with a constant-speed turbine with some valves and clever plumbing.

      • Re:variable speed (Score:5, Informative)

        by SargonZ ( 801566 ) on Friday July 30, 2004 @09:14AM (#9842787)
        Actually, current pacemakers can only be set to one speed, so people who have these devices already have the limitation of non-variable heartrate. While this is a setback for the pacemaker-using crowd, almost all agree that having a non-variable heart rate is better than having no heart rate at all.

        • Re:variable speed (Score:4, Informative)

          by CharlieG ( 34950 ) on Friday July 30, 2004 @12:04PM (#9844510) Homepage
          What? Almost all current generation pacemakers are rate responsive - they have a minimum rate, max rate, and rate curves, and they use various sensors (usually activity (movement) from what I understand, but also breathing rate) to change from one setpoint to another.

          I've been with my Dad when they check the programming of the resting and exercise rates on his pacemaker, and set them, and the transition point - It's all done with an inductive coil that is places over the main module of the pacemaker - they can even check the settings by phone

    • Re:variable speed (Score:5, Funny)

      by Kupek ( 75469 ) on Friday July 30, 2004 @09:41AM (#9843056)
      I can generally tell how hard I'm exercising by how much it hurts.

    • Re:variable speed (Score:3, Interesting)

      by Rogue974 ( 657982 )
      This is something I know about, I am an engineer and work with centrifugal pumps (engineering classification of these impeller/turbine pumps. You can make them variable speed and use the speed of the impeller to control the flow of the medium being pumped. There are many advantages to this, but it is not the common flow control scheme. Most of the time, the speed of the impeller is held constant and a control valve on the discharge side of the pump is opened and closed. As the discharge vale is open, fl

  • If I had no pulse... (Score:4, Interesting)

    by garcia ( 6573 ) * on Friday July 30, 2004 @08:58AM (#9842603)
    I wouldn't have to take the two different high-blood pressure meds that I do now. That would save me about $35/month and the random side effects that go with taking these medicines (shortness of breath when exercising, dizziness when getting up to fast, etc).

  • Pulse (Score:5, Interesting)

    by kc0re ( 739168 ) on Friday July 30, 2004 @08:58AM (#9842609) Journal
    I heard that people without pulse get a sense of disorientation and un-equilibrium. Especially those with screw drive hearts. Since the body has operated on a pulse for so many years, I have talked to people that have these screw drive heart devices, and they initially they couldn't even sleep at night because they didn't have the pulse in their ear.

    • Loud Pulse? (Score:3, Interesting)

      by abb3w ( 696381 )
      Um, I have NO medical training, but wouldn't your pulse being loud enough to hear be a sign of #$%^& high blood pressure... which would contribute to conditions that might need a heart replacement?

      I wouldn't know; In high school, my BP tended in the uncomfortably low 80/50 range... which caused at least one school nurse much consternation, as she couldn't find my pulse in wrist or throat. "Dear, are you sure you're breathing?" Since getting out from my mother's obsessively healthy "low salt/low fat" c

  • cosmetic surgery? (Score:5, Funny)

    by mblase ( 200735 ) on Friday July 30, 2004 @08:59AM (#9842610)
    I wonder how many goth vampire wannabes will elect to have these implanted, just to improve their authenticity?

  • Problems (Score:5, Interesting)

    by BWJones ( 18351 ) * on Friday July 30, 2004 @08:59AM (#9842620) Homepage Journal
    There are certain advantages to having a "pulse". Examples are: The alternating low and high pressures may allow the bodies baroreceptors to better control blood pressure and there are other important feedback mechanisms associated with having alternating high and low pressures in response to the heart contracting. I would worry that some of the new pumps could undermine those mechanisms.....

    • Re:Problems (Score:5, Interesting)

      by BWJones ( 18351 ) * on Friday July 30, 2004 @09:13AM (#9842764) Homepage Journal
      Perhaps I should have clarified some of this for the non-biologists here. Baroreceptors are receptors found in the aortic arch and internal carotid arteries that are sensitive not only to overall pressure in the cardiovascular system, but also to rates of pressure changes which are critically important in cases where you suddenly undergo rapid loss of blood pressure. (like when you are bleeding......alot). In cases like these, your body starts a series of physiologic changes to keep you alive and interfering with those sorts of things were what I was referring to.

      These issues may also be important for maintaining cardiovascular fitness as well as recovering from myocardial infarcts, and because the alternating pulse pressure is eliminated in turbine models, I would worry about possible losses of negative feedback which might result in runaway blood pressure which could lead to hemorrhagic strokes, kidney damage and other such unpleasantries.

      Oh, and since the Slashdot crowd appears to be preoccupied with sex, there is some evidence that penile erections are dependant upon alternating pressures to, ahem.....get the job done.

    • Re:Problems (Score:5, Insightful)

      by endx7 ( 706884 ) on Friday July 30, 2004 @09:29AM (#9842942) Homepage Journal
      The again, not having a working heart at all would probably undermine those mechanisms as well...

  • Interesting (Score:3, Interesting)

    by The-Bus ( 138060 ) on Friday July 30, 2004 @09:00AM (#9842630)
    I wonder what kind of effect this has on the body. Think about it, it's a pretty constant stream of blood flowing, as opposed to a stop/start of a pulse. Sure, there's several (I'd say at least... 5 or 6)* pulses per minute, but if I remember seeing video of a cellular level for vessels, it looked more like a semi-congested LA highway rather than a smooth flow. My guess is you'd probably need some sort of batteryless implant that would measure blood pressure [newscientist.com] as well.

    * Very technical here.

  • still a pulse (Score:3, Informative)

    by uid0mako ( 683312 ) on Friday July 30, 2004 @09:00AM (#9842633)
    from the article:
    "LVADs are not designed to replace the heart but are implanted alongside it under the rib cage."

    Therefore your heart is still there beating. This is just a supplement to it.

  • You have to rtfa (Score:3, Insightful)

    by bfree ( 113420 ) on Friday July 30, 2004 @09:02AM (#9842645)
    I can't believe that the body has no problem with living without a pulse! I would have expected complicated side effects (the lack of rythm disturbing some other micro or macro cycles). Any biologists in the house care to explain how far back in evolutionary terms it is since we last had no pulse? Does nothing depend on it or do we really have the diversity in our dna to adapt to the situation?

  • Internal Metronome (Score:3, Funny)

    by the darn ( 624240 ) on Friday July 30, 2004 @09:02AM (#9842647) Homepage
    Then I'd not only lack rhythm, I'd have no beat, either!
    Semi-seriously, though, would this eliminate the possibility of things, uh, throbbing?

  • 'Detecting a pulse' for those who don't have one (Score:5, Interesting)

    by EnglishTim ( 9662 ) on Friday July 30, 2004 @09:02AM (#9842653)
    A few months back I did a first-aid course at work. One of the interesting things I found out was the technique they use for checking to see if someone's heart is beating:

    Basically, you pinch their earlobe. This forces the blood out of the lobe, and then you let go. If colour returns to the lobe, then the heart is beating and blood has been pumped back in. If it does not then blood is no longer moving around the body.

    This technique would probably also work for those with no pulse.

  • Whatever You Do...Don't. Fall. Asleep. (Score:3, Funny)

    by GoatChunks ( 758276 ) on Friday July 30, 2004 @09:03AM (#9842662)
    With no pulse, I'd be afraid to take a nap in the park. "God damn it! I'm in the morgue again!"

    What would be worse though...I imagine most of the people getting these will be rather up in years. And, as old people and dads do, they will inevitably fall asleep in front of the TV.

    The first 6 or 7 times they do this, their family will think they're dead and will start going through his pockets. But then it becomes a "boy who cried wolf" scenario, and they think he's just sleeping when he's actually dead. Next thing you know, ol' grandpa has funked up the Lazy Boy, and they have to take him out in a bucket.

  • predicted lifespan (Score:5, Funny)

    by sacrilicious ( 316896 ) <qbgfynfu.opt@recursor.net> on Friday July 30, 2004 @09:04AM (#9842669) Homepage
    They also have no bearings, so they should last much longer than previous attempts. In fact, engineers don't give a predicted lifespan on these models.

    Marketer: So what's the predicted lifespan for these models?
    Engineer: We're, uh, not giving one.
    Marketer: Because it's so long?
    Engineer: I'm sorry, I didn't catch that. And now I have to go. (leaves)
    Marketer: (calling after him) I'll hold you to that!

  • Swoosh... Swoosh... Swoosh... (Score:3, Informative)

    by waynelorentz ( 662271 ) on Friday July 30, 2004 @09:05AM (#9842678) Homepage
    I think this has happened before (someone living without a pulse). There was some old man in Kentucky in the last year or so who was hooked up to an external blood pumping device. He was on the news because he lived for a few months, setting a record for the person who lived the longest without a heart. He was asked by a television reporter what it was like to not have a heart, and the guy said not having a pulse was the strangest thing he'd ever experienced. He said it was really really eerily quiet. Gross.

  • How would the body react? (Score:4, Insightful)

    by akiaki007 ( 148804 ) <aa316@nyWELTYu.edu minus author> on Friday July 30, 2004 @09:06AM (#9842689)
    Considering our veins are outfitted with nice valves that prevent the backflow of blood in between pumps of the heart, what would happen to them when they are no longer needed? One would think that they just wouldn't close, which I suppose is fine, but it just seems that they might create an unwanted side-effect.

    Also, it is possible that our organs aren't capabale of handling blood in a constant stream and they need those precious milliseconds of rest in between beats.

    Perhaps I should've stayed in medicine and then I'd know these answers, but since I didn't, anyone know or have a better theoretical idea?

  • Time to lower /. dating standards (Score:5, Funny)

    by Mr. Neutron ( 3115 ) on Friday July 30, 2004 @09:06AM (#9842692) Homepage Journal
    "Must have a pulse" is no longer a requirement. :-)

  • Oh no, the porn industry! (Score:3, Funny)

    by emorphien ( 770500 ) on Friday July 30, 2004 @09:11AM (#9842748)
    Hmm, this could be bad for any male porn star that needs a replacement heart. Aren't the male porn stars supposed to be able to hold a throbbing erection? Now it's gonna have the distinct hum of a turbine.

    Could be good, could be bad. Hmm.

  • Had it in the lab, years ago... (Score:4, Insightful)

    by gillbates ( 106458 ) on Friday July 30, 2004 @09:26AM (#9842914) Homepage Journal

    When I took my freshmen chemistry courses in college, we had electronic stirs - you'd drop this plastic coated magnetic "plug" in a beaker, and then set the beaker on the machine. An alternating magnetic field would cause the plug to spin, stirring the fluid.

    And now, 15 years later, someone finally figured out that you could apply the same principle to moving blood. Amazing.

    I've always wondered why people bleed to death on the operating room table from trauma. When I worked as a mechanic, I had a supply of various diameter tubings readily available so I could plug a vacuum leak when diagnosing a carburetor malfunction. I've never understood why surgeons can't do the same with blood vessels - the patient is bleeding from a major artery, and it never occurs to them that the could slice the artery in half and connect the ends with surgical tubing?

    I had always thought that there must be some really scientific reason for this, but now it occurs to me that it might just be ignorance. It took medical science 15 years to figure out that a lab stir would work better than bearings? I knew that as a freshmen! Ask the hubble designers - it uses frictionless magnetic bearings - maybe they could have clued someone in?

    • the reason many times is more ominous than what you mention. Say you're operating on a patient who has received previous radiation therapy. Sometimes the vessels will be just like butter. you can't place a stitch without it tearing. Meanwhile you're trying to pump in blood faster than they are bleeding out.

      say an artery is transected and the operating field fills with blood. They are bleeding out faster than 2 suckers can handle and you can't see to stop the bleed.

      say there is a arterial-venous malformati

  • With no pulse... (Score:3, Funny)

    by Neil Watson ( 60859 ) on Friday July 30, 2004 @09:27AM (#9842921) Homepage
    ..it's time to throw out your organ donar card.
  • He's Dead Jim. No wait wait he's alive.

  • BP and pulse are issues (Score:4, Insightful)

    by coyote_oww ( 749758 ) on Friday July 30, 2004 @09:56AM (#9843206)
    A lot of hospitals use automated blood pressure and pulse equipment to keep tabs on patients. Currently, this equipment can sound an alarm to attract the attention of a nurse if BP or pulse gets out of whack.

    So... it appears we'll have to come up with a new way to measure blood pressure, particularly. Presumably, the best way to do this is to fit the turbine with inlet and discharge pressure sensors, and a flow meter. Step 2 is to establish some sort of numbers for what is "normal" for turbine heart patients.

    This ups the ante for health care professionals by a bit. Not only do you need to know normal ranges, consequences, and treatments for standard BP and pulse ranges, you would need to be familiar with turbine pressure and flow ranges as well.

  • I have a low LVEF (Left Ventricular Ejection Fraction). A couple years ago while jogging I suffered a tachycardia (extremely rapid heart rate) that had me at around 300 beats a minute for 45 minutes. They gave me a defibrillator, but said that it was possible that the drugs might not be able to stop the decline of my LVEF and would require a heart transplant. Heart transplants are extremely hard to get, btw. Basically, if you need one, you're screwed.

    So to me, this device looks pretty darn cool. The cloned hearts grown from your own cells method is also pretty darn neat. The prospect of being an actual Borg is enticing, but the reservations about secondary effects of not having a pulse do give one pause. Yet if going with a cloned heart encourages the cloning of other organs, then perhaps that would be a better way to go. Decisions, decisions...

  • no pulse, no school? (Score:3, Funny)

    by !splut ( 512711 ) <sputNO@SPAMalum.rpi.edu> on Friday July 30, 2004 @10:11AM (#9843350) Journal
    Alas, some poor soul might not meet the primary requirement for our nation's great vocational colleges.

  • Whole Heart Version? (Score:5, Insightful)

    by Xesdeeni ( 308293 ) on Friday July 30, 2004 @10:41AM (#9843614)
    I saw this technology in a documentary on PBS at least fifteen years ago, but it was for a full heart replacement. They were reviewing artificial heart research after the Jarvik-7 was implanted. The odd thing was that the show went into a bit of detail about a centrifugal pump and its power supply, but I haven't seen anything about it since then.

    Apparently a small nuclear pellet was used in the battery, which was in a lead-lined container about the size of half a D-size battery. The battery could be implanted completely, unlike the Jarvik, which requires a dangerous (susceptible to infection) tube running through the skin to a suitcase sized pneumatic pump. The issue they focused on was the danger of the radioactive pellet. Apparently concern had been raised about the possibility of an artificial heart recipient being in a plane crash. The fear was that the radioactive battery would leak. So they went to great pains to test it, including shooting it out of a gun, to show it was safe.

    IIRC, the concept of being without a pulse, and the need for more research about this, was mentioned almost as an afterthought. But I've wondered ever since then what happened to this type of artificial heart. A completely self-contained apparatus would seem to be a godsend. But I always assumed that lack of pulse was the gotcha.

    I even discovered that Marilyn Vos Savant, whose Q&A column appears each week in the national Parade insert to many Sunday newspapers. is married to Robert Jarvik, and consdered writing him in care of her about this device. But I never got a round tuit [passco.com].

    Xesdeeni

  • Does anything depend on a pulse? (Score:5, Insightful)

    by Theovon ( 109752 ) on Friday July 30, 2004 @10:43AM (#9843622)
    Did you know that many clocks depend on your outlet current being exactly 60 (or 50) Hz? In the US, I believe federal regulations dictate that over some specified period of time, your wall outlet has to count to the right total number of oscillations. When load is high, causing the generators to spin slowly, the cycle count can get off by minutes, and the electric company has to make up for in off-peak periods by running the generators faster.

    In biological systems, we often see unusual dependencies. I think I read somewhere that certain birds can't swallow without gravity. And why not? It's there! Make use of it! That's the way evolution works. Nothing is more redundant than it needs to be (well, we can talk about transposons later). In humans, bone density is dependent on load, which is why our bones atrophe in weightlessness.

    So, given that we HAVE a pulse, I would be surprised if some part of your body didn't take advantage of it.

  • Living Without A Pulse (Score:5, Insightful)

    by Doc Miller ( 801590 ) on Friday July 30, 2004 @10:51AM (#9843689)
    I develped a pump for extracorporeal circulation of blood back in the mid 1970's and had to take a lot of these problems into account. My pump was pulsitile and had a very physiologic wave form including dichrotic notch. It also had 2 orders of magnitude less damage to red blood cells than the best pumps on the market at the time. (at least with the cow blood I experimented with) (Read on for an explanation of this) After spending a lot of money on patent lawyers, the device got shelved when I couldn't get a clear patent on it. I think people here on slashdot are missing the point of continuous (non-pulsitile) flow. The elasticity of the arteries especially the aorta actually adds to the pulsitile nature of blood flow. There is an artifact seen in blood pressure measurements called the dichrotic notch that is a direct result of this. If it is absent it is an indication that hardening of the arteries has taken place. The main purpose of circulation is to get blood to tissues and organs. Once there, it has to infiltrate the organs deeply in order to properly transfer oxygen and nutrients and carry away wastes. We were evolved with pulsitile flow and as a result the perfusion of organs and tissues is better with this type of fluid dynamic. That doesn't mean it won't work with constant flow, only that it won't be as efficient. It may take several years before these inefficencies result in some kind of problems. An increase in plaque deposition comes to mind because the tissues arent stretching and contracting. The other problem with turbines and impellers is the "waring blender effect" where the blood cells are "chopped up" by the spinning blades. This leads to hemolysis (release of hemoglobin into the blood form broken red blood cells) which puts a strain on the kidneys which aren't beilng perfused properly because of the non pulsitile flow, etc. etc. you get the picture. Anyway, it's interesting but not a permanent solution.

  • Old Science Show . . . (Score:3, Interesting)

    by Dausha ( 546002 ) on Friday July 30, 2004 @12:17PM (#9844675) Homepage
    I recall an old science show that said that the pulsating pressure was actually important for the human body. As I recall (and it's been nearly 20 years), the pulse helps the blood travel down certain pathways it couldn't reach under a steady push, and that it gives the body more time to transfer the goods, so to speak, intra-pulse. The discovery was made because the old dialysis machines delivered steady stream and they learned that not all the blood was circulated (some pooled).

    Not that I'm 100 percent sure about this. I like my ticker. I mean, with a non-pulse heart, if I were to pass out, they'd think I was dead.

  • Marine snipers could take longer shots (Score:5, Interesting)

    by osjedi ( 9084 ) on Friday July 30, 2004 @12:38PM (#9844925)
    My pulse is my biggest hurdle when taking high-power rifle shots at long rages (>600 meters). Without a pulse I could hold steady on a much smaller target. If you've never shot a scoped rifle, your pulse makes the crosshairs bounce with each heartbeat. You can slow your heart-rate down and time the beats, but it would still be nice to be able to hold steady on a 1,000 meter target and not have any movement. If you get excited it all goes out the window - if your pulse quickens you might as well be riding on the back of a horse.

    I imagine there are other tasks besides shooting that are impacted by pulse. I'm sure there are types of micro-surgery for example that could be negatively impacted by the surgeon's pulse.

  • Mean Arterial Pressure (Score:5, Informative)

    by steelheals ( 667878 ) on Friday July 30, 2004 @12:38PM (#9844927)
    I'll bite: I'm not golfing because I don't have the patience. IAAS (I am a Surgeon) and it would not be that difficult to measure a continuous flow generated pressure instead of a pulsed pressure. Plus you wouldn't have to teach us about turbines and such. For example, currently a patient in the ICU may have their blood pressure measured with an indwelling arterial line rather than a transduced cuff. We follow Mean Arterial Pressure (MAP) in this setting. Here's a quick definition: http://www.globalrph.com/map.htm (It was easier to google than find a textbook but this is short and sweet)- "Equation: MAP = [(2 x diastolic)+systolic] / 3 Diastole counts twice as much as systole because 2/3 of the cardiac cycle is spent in diastole. An MAP of about 60 is necessary to perfuse coronary arteries, brain, kidneys. Usual range: 70-110." We could still measure the equivalent of a MAP with a continuous pump. Some of the bioengineers who commented above probably know better, but whatever the range of pressure in the system from continuous pumping (whether it's always the same or if there's a smaller variation than the normal systolic/diastolic) it could still be accounted for and easily monitored and used to guide therapy. Probably the bigger problems are those already mentioned: baroreceptors that will now be in a new range, changes in coagulation, and destruction of blood borne cellular elements.

  • Athletic performance (Score:3, Interesting)

    by michael_cain ( 66650 ) on Friday July 30, 2004 @12:44PM (#9845018) Journal
    One of the factors that limits performance in athletic contests such as the recently completed Tour de France is cardiac output -- how much blood the rider's heart can pump. Fifty years from now will we have to have rules against riders with artificial hearts because they have an unfair advantage in cardiac capacity? Or will we borrow the kinds of regulations that the various auto racing organizations impose on engines? You can have an articial heart, but volume pumped must be constrained to be below X liters per minute, or the outlet into the aorta must be less than some number of square millimeters?

  • No pulse.... (Score:4, Insightful)

    by thewiz ( 24994 ) * on Friday July 30, 2004 @01:40PM (#9845835)
    As someone who was born with a congenital heart defect, has had three surgeries, and has been ticking with an artificial valve for the last 22 year, I'd be worried about not having a pulse.

    One of the things doctors/surgeons have noticed with heart patients that have their hearts stopped is that they lose all sense of time. I noticed it after my surgeries. I don't know if anyone has done research into the beating of the heart and the mechanisms in the brain that allow us to perceive the passage of time. Does the beat of the heart interact with the area(s) of the brain that perceive the passge of time? Do other bodily processes require a heartbeat for a "timeing signal"? I'm sure there are other questions to ask about this subject.

    Show me a man with a song in his heart and I'll show you a man with an AM/FM pacemaker!

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