Magnetohydrodynamic cardiac assist device

Details Magnetohydrodynamic cardiac assist device Magnetohydrodynamic cardiac assist device

1999-10-14

2002-08-27

Schaetzle, Kennedy (Department: 3762)

Surgery

Cardiac augmentation

With condition responsive means

C600S009000, C607S003000

Reexamination Certificate

active

06440059

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to cardiac assist devices, and in particular to a magnetohydrodynamic (MHD) heart pump which is less intrusive, and more effective, and easier to implement than prior art designs. The system of the present invention has no moving parts to wear out or break down, and is far less invasive than prior art systems.
The preferred embodiment of the present invention contemplates a cardio assist device utilizing MHD, wherein first and second, parallel electrodes forming an electrode assembly are placed, via the patient's femoral artery, into the aorta in the vicinity of the abdomen, which electrode assembly is exposed to a high density magnetic field generated outside of the patient. A current generated by a control unit energizes the first and second electrodes, and the blood situated therebetween, causing the high density magnetic field to interact with the energized blood, hydrodynamically motivating said blood to flow through the electrode assembly, in a uniform direction, thereby providing a fluid pumping force and pressure commensurate with the product of the magnetic field strength and the induced current in the blood vessel in accordance with MHD theory and practice, the general operational theory of which was first understood and explained by Scottish physicist James C. Maxwell in the mid-19th century.
In the preferred embodiment of the invention, the magnetic field is generated exterior of the patient via a superconducting magnet which is designed to produce a large magnetic field in the middle torso of the patient, so that the electrode assembly is generally centrally disposed within the magnetic field, along a longitudinal axis aligned with the aorta (and/or vena cava), and with electrode current flow generally orthogonal to the magnetic field.
Sensors monitoring the patient may utilize electrocardiogram (ECG), blood pressure, and blood flow, and other data to control the current in the blood in order to vary the pumping pressure and flow, so as to emulate the pumping action and intensity of the patients heart in real time, so as to lessen the trauma of artificial pumping assistance, or bypass on the patient.
The present device may also be utilized to provide full cardiac blood flow, as when a heart is stopped for bypass surgery, or to provide targeted limb or organ perfusion in a patient.
BACKGROUND OF THE INVENTION
Nearly one million acute cardiac failure fatalities occur each year in the U.S., many of which would have been preventable if there had been developed a suitable artificial heart. Heart assist or left ventricular assist devices (LVADs) are currently large, very invasive (requiring major chest surgery) and represent a significant patient risk.
These pumps require surgery to implant tubes, wires and other large devices to provide the motive pumping power which normally enters and exits the body cavity in the chest area. Typically large and percutaneous devices, they represent a significant surgical risk in their implementation, even if they do provide the necessary coronary assistance. Removing these devices requires another major bout of surgery with the attendant risks.
Another problem with current LVAD devices is the possibility that the quality of circulation provided by the units, which lack the sophistication of being able to emulate the natural rhythm of the heart, are that they may provide insufficient blood flow to the brain or other organs, to the extent that serious medical consequences arise. Finally, most of the LVAD pumps currently in use cause some destruction of red blood cells due to the destructive mechanical pumping means utilized.
A plethora of artificial heart designs have been contemplated and tested, including:
Cardio-pulmonary bypass machines, which are utilized in bypass surgery when the heart is stopped and the pumping action is taken over by a machine exterior from the patient that uses a mechanical pumping action such as a roller pump. These machines are for temporary use only, and require extensive thoracic invasion and medication for implementation and use. Long term use would be fatal, and even short term use can result in hemorrhaging, infection, renal failure, stroke, and other serious effects.
An Archimedes type screw device was available for some time that was inserted in the femoral artery and advanced into the Aorta as a type of mechanical LVAD. It would spin fast and propel blood along the length of the Aorta toward the feet.
An intra-aortic balloon pump (IAPB) has been around for about 20 years. It is inserted in the Aorta blown up partially obstructing the aorta when the heart pumps. This helps preserve the heart and brain blood flow in times of low cardiac output by lowering the afterload on the heart and increasing flow to the coronary arteries and carotid arteries.
Artificial hearts are generally mechanically similar to the mechanical LVADs, but are configured to replace the entire heart (both the left and right side). These devices have been implemented both internally and externally, but with likewise unsatisfactory results.
All of the above devices are very invasive, requiring massive and lengthy thoracic surgery . The support equipment for these pump designs generally require chest penetrations and significant cardiac trauma for installation, sometimes including penetration of the heart itself. Lastly, the mechanical pumping action in all of the above designs is believed to cause damage to the blood constituents.
A list of patents which may have some pertinence to the present invention include:
Patent Number
Inventor
Date of Issue
5911586
Siess et al
06/15/1999
5891134
Goble et al
04/06/1999
5888241
Jarvik
03/30/1999
5851174
Jarvik et al
12/22/1998
5763951
Hamilton et al
06/09/1998
5762599
Sohn
06/09/1998
5685700
Izraelec
11/11/1997
5668420
Lin et al
09/16/1997
5470208
Kletschka
11/28/1995
5385581
Bramm et al
01/31/1995
5003517
Greer, Jr
03/26/1991
4838850
Rosengart
06/13/1989
4265680
Pelser et al
05/05/1981
4242605
Schaffer
02/24/1981
U.S. Pat. No. 4,838,850 teaches an Electromedical Treatment Apparatus and which contemplates utilizing MHD effect to urge blood flow through blood vessels to increase circulation in targeted areas of the body. This patent does not contemplate the insertion of a device within the vasculature, but rather contemplates the use of magnetic lens to facilitate concentrated magnetic fields at a target area within the body, which may include a blood vessel, to utilize MHD effect to urge circulation of blood therethrough. (Col 7, lines 5-32).
U.S. Pat. No. 2,612,109 contemplates an earlier MHD pump design from the 50's.
U.S. Pat. No. 5,888,241 teaches a cannula pump driven by an impeller to assist the ventricals of the heart. The device comprises a tube which includes magnetic windings for driving the impeller.
See also 5,851,174.
U.S. Pat. No. 5,911,685 teaches an Intravascular micro axial pump which may be installed by advancing same through the patients vasculature, avoiding invasive chest surgery. The system incorporates an electrically driven, micro-motor having an impeller for pumping.
U.S. Pat. No. 5,385,581 teaches a Magnetically Suspended and Rotated Rotor in the form of a blood pump. This patent contemplates providing an impeller suspended and driven by a magnetic field, and includes feedback means in the form of sensors to monitor the patient, and computer control means to energize the coils with currents having frequency and amplitude adjusted in relation to the blood pressure at the pump inlet, so as to match the flow characteristics of the pump to physiological characteristics of the natural heart. Further, U.S. Pat. No. 5,928,131 also teaches a magnetically suspended, impeller driven heart pump with control means configured to simulate the beating of the patient's natural heart. See also U.S. Pat. Nos. 5,685,700 and 5,470,208, other magnetically suspended impeller systems configured to form blood pumps or the like.
U.S. Pat. No. 5,762,599 entitled “Magnetically-Coupled Implantable Medical Devices” teac

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