Pump- Technology and the Circulation Model Research and development; addendum

Pump types in comparision with the circulation system [top]

Introduction[back]

It is important to completely understand how the heart perform its pumping- and regulation-functions, to fully realise the significance of mechanical insufficiency of the heart.

The heart have been placed in the class of displacement pumps. The idea, that the heart should belong to the classes radial pumps or run through pumps, has been regarded as impossible.

The heart though, have characteristics that is not compatible with the characteristics of the displacement pumps:

• changed (or even lower) filling-pressure for increased frequency and increased minute-volume

• "check valves" that are closing without backflow

• the ability to keep two circulation systems in balance, without control-mechanism

We have been able to prove, that the heart do not belong to any of the previous known types of pumps. The heart have the best of the characteristics from the different types of pumps. These characteristics have been combined to a unique pump, with the following characteristics:

• possibility to have continuous inflow and pulsating outflow
• internal impedance close to zero
• no problems with filling during high frequencies
• increased (instead of decreased) stroke volume during increasing frequency
• the inflow directs the pump
• "the check valves" are closed by inflow (not by back-flow), which do not lead to any losses in stroke volume

Displacement pumps have non of the characteristics mentioned above, but all of them are represented in the heart.

We have developed a new type of pumps, based on the characteristics of the heart. We call them DeltaV pumps

Radial pumps[back]

Here we have centrifugal pumps and Archimedes screws.
With the circulation system of the human body in mind, the positive characteristics for this type of pumps are:

• continues inflow

• no valves are needed

• can be constructed in miniature, with high rotation speeds and rather large minute volumes

• simple, light and rather inexpensive constructions

With the circulation system of the human body in mind, the negative characteristics for this type of pumps are:

• continues outflow (not good for the vessels in long perspective)

• in- and outflow are always connected, which can produce severe regulation-problems

• problems with bearings and tight joints

• the efficiency do change, if there is changes in pressures and flows

Displacement pumps[back]

This group includes piston pumps, membrane pumps, hose pumps and gear pumps.
With the circulation system of the human body in mind, the positive characteristics for this type of pumps are:

• pulsating outflow

• the pressures in the inflow-chambers does not affect the inflow

• it is possible for the inflow (to some extent) to direct the pump (passive filling)

• the efficiency do not change, if there is changes in pressures and flows

With the circulation system of the human body in mind, the negative characteristics for this type of pumps are:

• pulsating inflow

• increasing inflow-pressure and problems with filling the pump, if the time period for filling is short

• one or two check valves is essential

• compliance-chamber is in most cases essential, if the pump is going to work in an electro-mechanical way, or is going to be implanted

• complicated technique, with weight- and volume-problem

Other pump types[back]

Here we have for example run through pumps (ejector pumps or secondary combustion chambers).

The characteristics of the run through pumps are very much alike those for the centrifugal pumps. The run through pumps works with the principle, that one flow give rise to another flow.

With the circulation system of the human body in mind, the positive characteristics for this type of pumps are:

• continues inflow

With the circulation system of the human body in mind, the negative characteristics for this type of pumps are:

• continues outflow

Delta-V pumps[back]

We have developed a new type of pumps, based on the characteristics of the heart. We call them DeltaV pumps.

With the circulation system of the human body in mind, the positive characteristics for this type of pumps are:

• continuous inflow

• pulsating outflow

• the inflow directs the pump

• can parry changes in outflow pressure, as long as the pump-power is sufficient; if it is not, the pump will stop

• variations in inflow-pressure do not affect the inflow

• internal impedance close to zero, even during high frequency

• no check valves

• the rapid filling make it possible for skeleton-muscles to drive the pump

With the circulation system of the human body in mind, the negative characteristics for this type of pumps are:

• new and untried technique

The Circulation Model[top]

To improve the understanding of the new knowledge and to facilitate for further research, development and education, Inovacor AB is developing a circulation model. It will fulfill all the conditions and the characteristics, that earlier only was possible to measure in the natural circulation system.

In The Circulation Model, a couple of variables could be varied in a randomized- or systematic way:

• peripheral resistance
• compliance
• diastolic pressure
• Bainbridges reflex (heart rate)
• total "blood" volume
• venous volume
• artery volume
• the regulating function of the inter-ventricle septum

A lot of experimental studies, which have direct correspondence to the natural circulation system (and earlier have been difficult to explain), is possible to perform with the parameters above.

In The Circulation Model the cause and result could be exactly presented in tables and in graphic. You learn which of the parameters that are important to control, and how to change the function of the delta-V pumps, inside or outside of a circulation system. You also have the possibility to compare the results, with respective parameters in the natural circulation system. It is an effective and lucid way to discover, how the new knowledge and technology effects the domains of medicine.

In Fig. 10.1 you can see an outline of The Circulation Model.

The water in the system (which simulate blood in the human body) is pumping into a chamber (1: Lung volume), by a deltaV pump (Right ventricle) (see Chapter 11).

The flow into the chamber is measured by a flow transmitter ( F₁: Flow transmitter no. 1).

The chamber is hermetically sealed and contains some air, which simulates the compliance of the pulmonic circulation.

On this chamber there is a drainage, with a valve that can be opened to decrease the water volume.

At the outflow part of the chamber is a resistance (R₁: Resistance in pulmonic circulation) adapted, which simulates the resistance in the pulmonic circulation.

The water that flows out of the chamber, arrives to another delta-V pump (Left ventricle). It is pumping the water into a chamber (2: Central artery volume).

Between the pump and the chamber a flow transmitter (F₂: Flow transmitter no. 2) and a pressure transmitter (B₁: baroreceptor no. 1), which simulate the baroreceptors in aortic arch and sinus caroticus, are adapted.

The chamber is hermetically sealed and contains some air, which simulates the compliance of the systemic circulation.

On this chamber there is a drainage, with a valve that can be opened to decrease the water volume.

At the outflow part of the chamber is a variable resistance (R₂: Resistance in systemic circulation) adapted, which simulates the variable resistance in the systemic circulation.

The next site for the flowing water is a new chamber (3: Periphery artery volume). On this chamber, there is a connection with a water-tap, to make it possible to increase the water volume in the system.

There is also a pipe between Periphery artery volume and another chamber (4: Venous volume), which have a connection with a chamber (5: Regulatory part of venous volume).

Regulatory part of venous volume is possible to increase or decrease, by help of an electric motor. That simulate the possibility for the venous system to vary the pooling of blood.

There is a drainage on this chamber, with a valve that can be opened to remove some water from the system.

From Venous volume the water pass into Right ventricle, and between these vessels there is a pressure transmitter (B₂: baroreceptor no. 2), which simulate the baroreceptors in the left atrium of the heart.

Both Right ventricle and Left ventricle are connected with a chamber (6: Regulatory function of the inter-ventricular septum), that contains a membrane, which is flexible and separates Right ventricle from Left ventricle.

Inovacor AB have today a prototype of The Circulation Model, which do not have the chamber Regulatory function of the inter-ventricular septum . The company have during a long period prosecuted pilot studies according to the prototype model.

A lot of changes must be done in the medicine area, to make it possible to follow and register the function and roll of the heart in the circulation system. Here follows some examples:

• methods and instruments for measurements of static- and dynamic pressure

• methods and calculation models to splitting the total blood volume in central/periphery venous volume and central/periphery artery volume

• methods and instruments for calculation of the tonus in the veins

• new hardware- and software programs is needed in all investigation methods (X-ray, gamma camera, echocardiography and MRI), to measure and register the movements of the AV-plane and inter-ventricular septum. Based on that, it is possible to estimate the condition of the heart.

We are planning to develop new artificial heart- and lung-machines, left- and right assist devices (LVAD and RVAD), plus methods to reconstruct the natural heart. By doing that, we hope that we can contribute to avoid invalidating heart failures in the future.