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Patent Issued for Total Artificial Heart System for Auto-Regulating Flow and Pressure Balance

August 17, 2014

By a News Reporter-Staff News Editor at Heart Disease Weekly -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventors Frazier, Oscar H. (Houston, TX); Cohn, William (Houston, TX), filed on May 27, 2010, was published online on July 29, 2014 (see also Newheart Medical Devices, LLC).

The patent's assignee for patent number 8790399 is Newheart Medical Devices, LLC (Houston, TX).

News editors obtained the following quote from the background information supplied by the inventors: "Over 50,000 people die each year because of congestive heart failure, a condition that often cannot be treated with drug or surgical therapies. Moreover, nearly 550,000 new patients are diagnosed with congestive heart failure each year. For most patients that suffer heart failure, the only option is heart transplantation via an organ donor or by artificial means. The scarcity of suitable donor hearts has left patients and doctors with no choice but to look to artificial heart therapies. Fortunately, great strides have been made in the development of ventricular assist devices (VADs). Instead of totally replacing heart function, a VAD augments the existing heart's ability to pump blood. These devices have saved many patients who would not have survived without a heart transplant. Despite it success, current VAD technology still has much room for improvement. The development of a viable long term total artificial heart replacement still remains the ultimate goal.

"In the past, total artificial hearts (TAHs) have been based on a pulsatile system in an effort to mimic the human heart. However, such devices require prosthetic valves and external vent tubes. The prosthetic valves in pulsatile systems are prone to causing blood damage and blood clots while external vent tubes are a likely source for infection. Furthermore, current TAHs are still large, expensive to produce, and not anatomically suitable for implantation in small adults and children. In recent years, research has focused on continuous flow systems as an alternative to the traditional pulsatile model. In a continuous flow system, blood is continuously pumped through the body rather than pulsing the blood rhythmically as in the human heart.

"Continuous flow systems offer several advantages over pulsatile systems. First, continuous flow pumps are generally smaller than pulsatile pumps. Shrinking the size of artificial heart devices will allow doctors to treat women and small children who previously were not candidates for pulsatile TAHs. Second, continuous flow pumps consume less energy than pulsatile systems. This property is important for quality of life issues, allowing the device to run on smaller batteries. Finally, continuous flow pumps have been developed that are magnetically driven with no mechanical bearings or valves, dramatically decreasing any chance of blood damage or long term failure.

"Unfortunately, continuous flow pumps are not without drawbacks. The main problem with continuous flow pumps is their inability to auto-regulate or balance flow and pressure across the left and right side of the heart. Even in a healthy human heart, there is a 10 to 15 percent difference in flow and pressure between the left and right sides of the heart. This difference is because of the greater resistance in the systemic circulation i.e. the left side of the heart. In biventricular assist devices, where the patient's natural atria are utilized, an inability to auto-regulate flow and pressure may result in atrial collapse, a potentially fatal condition.

"Prior attempts at overcoming this problem have utilized electronic monitoring and control for changing the pump speed. However, any solution involving electronic control systems will likely be unsuitable for long term patient survival due to the inherent limitations on the reliability and longevity of electronic sensors and control systems. Therefore, the ideal continuous flow system would contain a means to auto-regulate without the need for electronic control systems.

"Consequently, there is a need for a simple system to auto-regulate flow and pressure balance in TAHs employing continuous flow pumps that may be used to temporarily or permanently replace a defective human heart."

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors' summary information for this patent: "The present invention provides a system for auto-regulating the flow and pressure balance in continuous flow TAHs. In the mammalian heart, the nervous system auto-regulates the flow and pressure balance across the left and right side of the heart in response to physiological changes in the body. However, current continuous flow TAHs do not have the benefit of the nervous system and must rely on electronic means to control flow and pressure. Not only is the longevity of such electronic systems a point of weakness, but the means by which they operate are often very complex. In order to avoid running wires through the patient's skin, researchers have moved toward employing wireless technology as a substitute, further complicating an already intricate device. The present invention accordingly provides a novel, simple approach to regulating flow and pressure balance by emulating the mammalian heart's Frank-Starling mechanism.

"The Frank-Starling mechanism is the means by which the heart pumps harder when blood volume passing through it increases. The greater the blood volume in the heart, the more the cardiac muscles are stretched. Much like a rubber band, the heart exerts more force in pumping blood when it is filled with a greater volume. Therefore, in an embodiment comprising more than one atrial chamber, the system may comprise a means for transmitting fluid pressure between the left and right atria to auto-regulate flow and pressure balance in continuous flow TAHs with less need for electronic sensors.

"In an additional embodiment, these and other needs in the art are addressed by a system comprising an atrial reservoir, said atrial reservoir comprising inlets and outlets connectable to a mammalian cardiovascular system, and at least first and second continuous pumps connected to said atrial reservoir. Moreover, the system may comprise at least first and second atrial chambers and a means for transmitting fluid pressure between first and second atrial chambers. In other embodiments, the atrial reservoir may comprise a single atrial chamber. The continuous flow pumps may then be connected to the pulmonary artery, the aorta, or both. The system may utilize any type of continuous flow pump including rotary axial flow pumps or rotary centrifugal pumps. The atrial reservoir preferably may mimic the Frank-Starling mechanism of the human heart. The size of the atrial reservoir is optimized to minimize blood damage and negative pressure conditions. The invention operates as a complete TAH system and requires substantially less electronic control for pressure and flow balance than the prior art.

"Thus, the present invention comprises a combination of features and advantages that enable it to overcome the problems of prior devices. The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims."

For additional information on this patent, see: Frazier, Oscar H.; Cohn, William. Total Artificial Heart System for Auto-Regulating Flow and Pressure Balance. U.S. Patent Number 8790399, filed May 27, 2010, and published online on July 29, 2014. Patent URL:

Keywords for this news article include: Biomedical, Cardiology, Pediatrics, Technology, Blood Volume, Hemodynamics, Cardio Device, Heart Disease, Heart Failure, Artificial Heart, Cardiovascular Diseases, Newheart Medical Devices LLC.

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Source: Heart Disease Weekly

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