The Development of a Control Method for a Total Artificial Heart Using Mixed Venous Oxygen Saturation

Nakamura, Makoto; Masuzawa, Toru; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Nakamura, Tomomichi; Zhang, Bin; Nakatani, Takeshi; Takano, Hisateru; Ohno, Takashi

doi:10.1046/j.1525-1594.1999.06314.x

Cited by 14 publications

(5 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although we set flowmeters to the LVAD and the RVAD outflow cannula in this series, more small sensor or sensorless estimation of flow rate should be essential for clinical use (16). To decide the target LVAD flow that matches various peripheral oxygen demands, a small and implantable Sv o 2 sensor is necessary for implantable VAD (17).…”

Section: Discussionmentioning

confidence: 99%

Control Strategy for Biventricular Assistance with Mixed‐Flow Pumps

Endo¹,

Araki

Oshikawa

et al. 2000

Artificial Organs

View full text Add to dashboard Cite

A left ventricular assist device (LVAD) is an effective method to rescue severe heart failure. Although some require a biventricular assist, the control method for the biventricular assist device (BVAD) with a rotary pump is rarely shown. The objective of this study was to investigate the strategy for controlling BVAD with rotary pumps by in vivo studies. Using 5 piglets, we set a BVAD through a left thoracotomy and made global ischemia for 30 min by clamping the base of the ascending aorta. After unclamping, the analysis of pumping performance acted for 6 h reperfusion. We set the target flow of the LVAD and set the right ventricular assist device (RVAD) speed limit as less than when the atrial collapse occurs. To detect the ventricular collapse without any specific sensor, we calculated the index of current amplitude from motor current waveform and simultaneous mean current value. In all cases, over 6 h of observation was performed, and the RVAD was weaned almost automatically.

show abstract

Section: Discussionmentioning

confidence: 99%

Control Strategy for Biventricular Assistance with Mixed‐Flow Pumps

Endo¹,

Araki

Oshikawa

et al. 2000

Artificial Organs

View full text Add to dashboard Cite

show abstract

“…To this fundamental logic providing a Starling‐like response, we contemplate adding an algorithm which transiently augments output increase in response to exercise. An acceleration sensor signal and mixed venous oxygen saturation sensor signal are being investigated to be utilized for this purpose ( 13, 14).…”

Section: Discussionmentioning

confidence: 99%

In Vivo Evaluation of the National Cardiovascular Center Electrohydraulic Total Artificial Heart

et al. 1999

Self Cite

View full text Add to dashboard Cite

We have been developing an electrohydraulic total artificial heart system. The system comprises an intrathoracic pumping unit composed of diaphragm type ellipsoidal blood pumps and an energy converter in addition to an electronics unit. The in vivo performance of the pumping unit was evaluated in a series of animal implantations with 3 calves weighing 62-85 kg. An interatrial shunt 4.5 mm in diameter was made in the atrial septum to compensate left-right imbalance. Two calves died early postoperatively, one of external controller power failure and the other of interatrial shunt stenosis due to thrombus formation. One calf, however, survived over 10 days under stable circulatory conditions. No abnormality was found in the oxygen metabolic condition or in major organ functions. The generation and dissipation of heat from the device was acceptable. This animal died of device malfunction caused by energy converter bearing breakdown. The device demonstrated a good anatomic fit without compromising the great vessels and adjacent tissues. It is concluded that the pumping unit has a sufficient in vivo basic performance although appropriate countermeasures are to be implemented against the detected problems concerning mechanical durability and interatrial shunt patency.

show abstract

“…Although such a controller provides some advantages when compared to an open-loop fixed pump speed operation, it does not necessarily provide a mechanism to prevent the occurrence of suction. An investigation using oxygen saturation of the blood for feedback control purpose has also been reported in [12]. However this approach requires implanted transducers, and is limited in its ability to respond to sudden changes in the patient's blood demand.…”

Section: Introductionmentioning

confidence: 99%

A Dynamical State Space Representation and Performance Analysis of a Feedback-Controlled Rotary Left Ventricular Assist Device

Simaan¹,

Ferreira²,

Chen³

et al. 2009

IEEE Trans. Contr. Syst. Technol.

View full text Add to dashboard Cite

The left ventricular assist device (LVAD) is a mechanical device that can assist an ailing heart in performing its functions. The latest generation of such devices is comprised of rotary pumps which are generally much smaller, lighter, and quieter than the conventional pulsatile pumps. The rotary pumps are controlled by varying the rotor (impeller) speed. If the patient is in a health care facility, the pump speed can be adjusted manually by a trained clinician to meet the patient's blood needs. However, an important challenge facing the increased use of these LVADs is the desire to allow the patient to return home. The development of an appropriate feedback controller for the pump speed is therefore crucial to meet this challenge. In addition to being able to adapt to changes in the patient's daily activities by automatically regulating the pump speed, the controller must also be able to prevent the occurrence of excessive pumping (known as suction) which may cause collapse of the ventricle. In this paper we will discuss some theoretical and practical issues associated with the development of such a controller. As a first step, we present and validate a state-space mathematical model, based on a nonlinear equivalent circuit flow model, which represents the interaction of the pump with the left ventricle of the heart. The associated model is a six-dimensional vector of time varying nonlinear differential equations. The time variation occurs over four consecutive intervals representing the contraction, ejection, relaxation, and filling phases of the left ventricle. The pump in the model is represented by a nonlinear differential equation which relates the pump rotational speed and the pump flow to the pressure difference across the pump. Using this model, we discuss a feedback controller which adjusts the pump speed based on the slope of the minimum pump flow signal, which is one of the model state variables that can be measured. The objective of the controller is to increase the speed until the envelope of the minimum pump flow signal reaches an extreme point and maintain it afterwards. Simulation results using the model equipped with this feedback controller are presented for two different scenarios of patient activities. Performance of the controller when measurement noise is added to the pump flow signal is also investigated.

show abstract

The Development of a Control Method for a Total Artificial Heart Using Mixed Venous Oxygen Saturation

Cited by 14 publications

References 13 publications

Control Strategy for Biventricular Assistance with Mixed‐Flow Pumps

Control Strategy for Biventricular Assistance with Mixed‐Flow Pumps

In Vivo Evaluation of the National Cardiovascular Center Electrohydraulic Total Artificial Heart

A Dynamical State Space Representation and Performance Analysis of a Feedback-Controlled Rotary Left Ventricular Assist Device

Contact Info

Product

Resources

About