An Engineering Analysis of the Aortic Valve Dynamics in Patients with Rotary Left Ventricular Assist Devices

Abstract

The use of a rotary Left Ventricular Assist Device (LVAD) as a bridge-to-recovery treatment is gaining considerable attention in the LVAD research community. Using a mathematical model of the cardiovascular-LVAD system, this paper intends to define the critical control parameters in terms of power and rotational speed of the LVAD to ensure normal dynamics of the aortic valve for different levels of patient's activity and severity of heart failure. The effects of permanent closure of the aortic valve on the hemodynamics of the patient and the pump flow characteristics, if the critical control values are exceeded, are also examined. Additionally, LVAD power and speed control parameters that yield a given percentage of the cardiac cycle during which the aortic valve remains open are examined indicating that the severity of the heart failure is a very important factor in deciding the appropriateness of the LVAD as a bridge-to recovery treatment.

A Non-Invasive Physiological Control System of a Rotary Blood Pump Based on Preload Sensitivity: Use of Frank–Starling-Like Mechanism

“…The selection of an optimal scale factor (K) for patients with different levels of heart failure was explained in this paper in order to provide the appropriate pump flow. As suggested in Table 3, this paper approximately graded the degree of heart failure into severe heart failure (Emax = 0.5), moderate heart failure (Emax = 1.0), and mild heart failure (Emax = 1.5) [18].…”

“…As a result, the system responded to the changes in the physiological state of the patient in time. Mahdi Mansouri et al proposed a preload-based Frank-Starling system where they measured average preload to determine the patient's working point and cost for at least two cycles and could not successfully respond to changes in the physiological state of the patient in time [18].…”

A Non-Invasive Physiological Control System of a Rotary Blood Pump Based on Preload Sensitivity: Use of Frank–Starling-Like Mechanism

“…The selection of an optimal scale factor (K) for patients with different levels of heart failure was explained in this paper in order to provide the appropriate pump flow. As suggested in Table 3, this paper approximately graded the degree of heart failure into severe heart failure (Emax = 0.5), moderate heart failure (Emax = 1.0), and mild heart failure (Emax = 1.5) [18].…”

“…As a result, the system responded to the changes in the physiological state of the patient in time. Mahdi Mansouri et al proposed a preload-based Frank-Starling system where they measured average preload to determine the patient's working point and cost for at least two cycles and could not successfully respond to changes in the physiological state of the patient in time [18].…”

Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

“…The cardiovascular-pump model as explained in Section 2.1 involves a few model parameters, which can be used to represent the physiological dynamics of the heart supported with a LVAD. As previously reported, parameters R s , R M , and heart rate (HR) can govern the behaviour of the cardiovascular-pump system [13]. Thus, we propose to investigate their effect on the dynamics of the aortic valve and the cardiac output.…”

Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing

“…For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that. 76 In order to replicate the hemodynamics and mechanical properties of the ventricle, some research groups applied an external pressure to the 3D model so to mimic either the volume's or the pressure's waveform. A limitation of this approach is the passive behavior of the model.…”

“…However, only a small range of cardiovascular sites can be replicated in this way. For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that 76 …”

A Non-Invasive Physiological Control System of a Rotary Blood Pump Based on Preload Sensitivity: Use of Frank–Starling-Like Mechanism

“…The selection of an optimal scale factor (K) for patients with different levels of heart failure was explained in this paper in order to provide the appropriate pump flow. As suggested in Table 3, this paper approximately graded the degree of heart failure into severe heart failure (Emax = 0.5), moderate heart failure (Emax = 1.0), and mild heart failure (Emax = 1.5) [18].…”

“…As a result, the system responded to the changes in the physiological state of the patient in time. Mahdi Mansouri et al proposed a preload-based Frank-Starling system where they measured average preload to determine the patient's working point and cost for at least two cycles and could not successfully respond to changes in the physiological state of the patient in time [18].…”

Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

“…The cardiovascular-pump model as explained in Section 2.1 involves a few model parameters, which can be used to represent the physiological dynamics of the heart supported with a LVAD. As previously reported, parameters R s , R M , and heart rate (HR) can govern the behaviour of the cardiovascular-pump system [13]. Thus, we propose to investigate their effect on the dynamics of the aortic valve and the cardiac output.…”

Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing

“…For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that. 76 In order to replicate the hemodynamics and mechanical properties of the ventricle, some research groups applied an external pressure to the 3D model so to mimic either the volume's or the pressure's waveform. A limitation of this approach is the passive behavior of the model.…”

“…However, only a small range of cardiovascular sites can be replicated in this way. For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that 76 …”

A Non-Invasive Physiological Control System of a Rotary Blood Pump Based on Preload Sensitivity: Use of Frank–Starling-Like Mechanism

“…The selection of an optimal scale factor (K) for patients with different levels of heart failure was explained in this paper in order to provide the appropriate pump flow. As suggested in Table 3, this paper approximately graded the degree of heart failure into severe heart failure (Emax = 0.5), moderate heart failure (Emax = 1.0), and mild heart failure (Emax = 1.5) [18].…”

“…As a result, the system responded to the changes in the physiological state of the patient in time. Mahdi Mansouri et al proposed a preload-based Frank-Starling system where they measured average preload to determine the patient's working point and cost for at least two cycles and could not successfully respond to changes in the physiological state of the patient in time [18].…”

Stochastic Modeling and Dynamic Analysis of the Cardiovascular System with Rotary Left Ventricular Assist Devices

“…The cardiovascular-pump model as explained in Section 2.1 involves a few model parameters, which can be used to represent the physiological dynamics of the heart supported with a LVAD. As previously reported, parameters R s , R M , and heart rate (HR) can govern the behaviour of the cardiovascular-pump system [13]. Thus, we propose to investigate their effect on the dynamics of the aortic valve and the cardiac output.…”

Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing

“…For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that. 76 In order to replicate the hemodynamics and mechanical properties of the ventricle, some research groups applied an external pressure to the 3D model so to mimic either the volume's or the pressure's waveform. A limitation of this approach is the passive behavior of the model.…”

“…However, only a small range of cardiovascular sites can be replicated in this way. For instance, in a healthy patient the ventricular compliance varies roughly from 0.28 to 10 ml/mm Hg during a cardiac cycle due to the complex action of the muscles, and no material can mimic that 76 …”