HOW THE HEART WORKS

Too invest in SSH I think you should have an understanding of the unique properties of the heart, i.e.. that output is more accurately controlled by input, tension in the system (receptors/neurohormonal) not by stroke rate or stroke volume (ie. cardiac output) .


** Posted this on SA


Before anyone talks cardiac output etc. I think they should read this book by Anderson and especially look at the video.
Best way I can begin to grasp the heart is this. Not correct but a start.
Imagine a rope stretched continuously around a set of pulleys. Grab the rope and pull-push it . All parts of the rope move. Energy in equals energy out.
This is not the heart.
The heart splits the rope. It has a beginning and an end. Push the top of the rope and it just crumples up. It does not drag the bottom of the rope with it.
How does the heart get around this?
It flicks the rope and sends a pulse down it.
Imagine a many segmented rope.
The heart cuts off a segment off the bottom and adds the segment with energy to the top of the rope causing a "flick". A wave travels down the rope moving every segment forward one place.
To increase cardiac volume, how?
The heart only works efficiently one segment at a time, so jamming two segments in at a time is going to decrease the energy of the flick, given the resistance/capacitance of system the wave is not going to make it too the other end to get another two segments in the heart.
Rule out increasing stroke volume.
Leaves only increasing stroke rate.
So we increase stroke rate.
This doesn't work either. Why? The wave just travels at the same speed down the system. So if the heart is moving at two beats ie. two segments a second and the segments are arriving at only one segment a second at the other end meaning the heart can only beat at one segment a second. Again the heart would be under stress trying to pump half sections which it is not designed to do.
How does it work?
The heart increases the stroke rate and the circulatory system increases in tension sending the waves down faster. So the heart beats at two beats/sections a second and two sections arrive at the bottom of the rope every second.
This is not an overly accurate description of how the heart works but I think it does convey a reasonable inference of how it works.
So whats the most important variable of the heart.
Its the ejection fraction. It tells you the heart is working efficiently one segment in and one segment out at a time.
Cardiac output? At double the stroke rate the heart could be pumping half a segment inefficiently and doing damage to itself but cardiac output would be the same but blood would not be moving around the body per second the same as a normal heart because the "flick" would be too weak, resistance/capacitance too great. At half the stroke rate the heart moving two segments at a time would have the same cardiac output again but again because of a weakened "flick" blood flow round the system would be comprimised.
The other main variable is the tension in the system making sure, exactly sure that the right tension exists so that exactly the right number of "segments" turn up per second to match the number of beats per second wanted.
The tension is controlled by the receptor/ neurohormonal system. Whatever the output wanted it is all controlled by the input, this is why the receptor/neurohormonal hormonal system is so important.
I'd urge great caution in using Cardiac output as an important variable in isolation because it could well be misleading. As well as ignoring the receptor/neurohormonal system because it controls the output of and important stress factors on the heart.
I'd also dump any idea despite SSH's still (idiotically) using it on the web site that IABD's have any relationship what so ever to C-Pulse's mechanism of efficacy.