Physiologic Control of Cardiac Assist Devices

Hall, Alden W.; Soykan, Orhan; Harken, Alden H.

doi:10.1111/j.1525-1594.1996.tb04438.x

Cited by 19 publications

(14 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A key requirement in realizing such a control strategy is the ability to discern with great accuracy, and indeed avoid, those pumping states which are potentially harmful to the patient. Such states include collapse of the ventricle due to over-pumping (ventricular suction), or pump back flow (regurgitation) as a result of under-pumping [1].…”

Section: Introductionmentioning

confidence: 99%

Automated Non-invasive Detection of Pumping States in an Implantable Rotary Blood Pump

Karantonis

Cloherty

Mason³

et al. 2006

2006 International Conference of the IEEE Engineering in Medicine and Biology Society

View full text Add to dashboard Cite

With respect to rotary blood pumps used as left ventricular assist devices (LVADs), it is clinically important to control pump flow to avoid complications associated with over-or under-pumping of the native heart. By employing only the non-invasive observer of instantaneous pump impeller speed to assess flow dynamics, a number of physiologically significant pumping states may be detected. Based on a number of acute animal experiments, five such states were identified: regurgitant pump flow (PR), ventricular ejection (VE), non-opening of the aortic valve (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). Two broader states, normal (corresponding to VE, ANO) and suction (corresponding to PVC-I, PVC-C) were readily discernable in clinical data from human patients implanted with LVADs. Based on data from both the animal experiments (N=6) and the human patients (N=10), a strategy for the automated non-invasive detection of significant pumping states has been developed and validated. Employing a classification and regression tree (CART), this system detects pumping states with a high degree of accuracy: state VE -87.5/100.0% (sensitivity/specificity); state ANO - 98.1/92.5%; state PVC-I - 90.0/90.2%; state PVC-C - 61.2/98.0%. With a simplified binary scheme differentiating suction and normal states, both states were detected without error in data from the animal experiments, and with a sensitivity/specificity, for detecting suction, of 99.2/98.3% in the human patient data.

show abstract

Section: Introductionmentioning

confidence: 99%

Automated Non-invasive Detection of Pumping States in an Implantable Rotary Blood Pump

Karantonis

Cloherty

Mason³

et al. 2006

2006 International Conference of the IEEE Engineering in Medicine and Biology Society

View full text Add to dashboard Cite

show abstract

“…While research for controlling an artificial heart only with electric power consumption of the system was under way without using a viable sensor due to its poor durability and reliability, research was conducted again that uses a pressure sensor to quantify the input pressure of an artificial heart (9)(10)(11). Comparably, the AnyHeart used one pressure sensor to measure the pre-and afterload at the same time, possibly controlling the artificial heart according to the patient's physiological conditions with relative ease (12)(13)(14).…”

mentioning

confidence: 99%

Applications of Artificial Heart Research to the Life-Saving Device

Min

2013

Artificial Organs

View full text Add to dashboard Cite

“…In order to achieve such a control strategy, a major design goal for iRBPs is the ability to reliably and accurately detect pumping states that cause such deleterious effects as ventricular collapse due to overpumping, or pump backflow (regurgitation) as a result of underpumping (1). Naturally, the ideal control set point is where left ventricular (LV) ejection is occurring and there is a net positive flow through both the aortic valve (AV) and the pump.…”

mentioning

confidence: 99%

Classification of Physiologically Significant Pumping States in an Implantable Rotary Blood Pump: Effects of Cardiac Rhythm Disturbances

et al. 2007

View full text Add to dashboard Cite

Abstract:In a clinical setting it is necessary to control the speed of rotary blood pumps used as left ventricular assist devices to prevent possible severe complications associated with over-or underpumping. The hypothesis is that by using only the noninvasive measure of instantaneous pump impeller speed to assess flow dynamics, it is possible to detect physiologically significant pumping states (without the need for additional implantable sensors). By varying pump speed in an animal model, five such states were identified: regurgitant pump flow, ventricular ejection (VE), nonopening of the aortic valve over the cardiac cycle (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). These states are described in detail and a strategy for their noninvasive detection has been developed and validated using (n = 6) ex vivo porcine experiments. Employing a classification and regression tree, the strategy was able to detect pumping states with a high degree of sensitivity and specificity: state VE-99.2/100.0% (sensitivity/specificity); state ANO-100.0/100.0%; state PVC-I-95.7/91.2%; state PVC-C-69.7/98.7%. With a simplified binary scheme differentiating suction (PVC-I, PVC-C) and nonsuction (VE, ANO) states, both such states were detected with 100% sensitivity. Current commercially used implantable rotary blood pumps (iRBPs) make little or no attempt to automatically control pump speed to optimize ventricular assistance. In order to achieve such a control strategy, a major design goal for iRBPs is the ability to reliably and accurately detect pumping states that cause such deleterious effects as ventricular collapse due to overpumping, or pump backflow (regurgitation) as a result of underpumping (1). Naturally, the ideal control set point is where left ventricular (LV) ejection is occurring and there is a net positive flow through both the aortic valve (AV) and the pump.A state that would be of long-term concern to a patient would occur at higher relative pump speeds when there is insufficient blood in the ventricle to sustain normal LV ejection and the AV remains closed throughout the entire cardiac cycle. In this instance there is no flow through the AV and the possibility of blood stasis distal to the AV, which could lead to significant patient complications due to clotting. However, it has been recognized (2,3) that the aim of ensuring AV opening is often infeasible in patients with LV failure. The lack of native heart contractility in such patients means that in order to attain a level of pump flow which adequately perfuses the body, a pump speed which produces the state of full AV closure is often required. Even higher speeds would result in partial or total ventricular collapse as the volume of blood drawn from the ventricle chamber is increased to a level at which pulmonary supply cannot meet pump demand. Deleterious outcomes could also occur at lower relative pump speeds where there is regurgitant flow through the pump.Experimentation in the transition of pumping stat...

show abstract

Physiologic Control of Cardiac Assist Devices

Cited by 19 publications

References 17 publications

Automated Non-invasive Detection of Pumping States in an Implantable Rotary Blood Pump

Automated Non-invasive Detection of Pumping States in an Implantable Rotary Blood Pump

Applications of Artificial Heart Research to the Life-Saving Device

Classification of Physiologically Significant Pumping States in an Implantable Rotary Blood Pump: Effects of Cardiac Rhythm Disturbances

Contact Info

Product

Resources

About