Analog Simulation of Aortic Stenosis

Sever, Matjaž; Ribarič, Samo; Runovc, Franc; Kordaš, M.

doi:10.5772/20919

Cited by 2 publications

(10 citation statements)

References 25 publications

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“…The pumping action of the heart is determined not only by preload and afterload, but also by the capacitance of the attached artificial vascular circuit [16]. Its basic behavior is similar to the simulation of a simplified human cardiovascular system [16] which has been continuously upgraded [18, 19]. …”

Section: Discussionmentioning

confidence: 99%

“…Details of how to simulate the atrium and ventricle—both as input-sensitive pumps—and the attached vessels are described elsewhere (e.g., [17–19, 23]). To summarize, the main sections of the EECs model are as follows.

The “systemic” circuit is made up by a chain of resistor/capacitor segments.

…”

Section: Methodsmentioning

confidence: 99%

“…[18, 19]). The corresponding mitral and aortic flow is measured as a voltage drop across the 1 Ω resistor (Figure 2) as described [18, 19]. …”

Section: Methodsmentioning

confidence: 99%

“…We have found the use of lumped parameter models with computer-simulated equivalent electronic circuits (EECs) useful for understanding basic physiology concepts and for educational use [16, 17]. By appropriate upgrading, we could use these EECs for simulating qualitatively, in some cases even quantitatively, cardiovascular physiology and cardiovascular pathology, including well-known clinical conditions [18, 19]. This highly upgraded EECs lumped parameter model enables us to record many interesting variables, for example, the time course of atrial and ventricular pressure during systole and diastole, the rate of myocardial contraction and relaxation, the valve flows, the ventricular volume taking into consideration the resetting of the sympathetic nervous tone in the heart and systemic circuit, the fluctuating intrathoracic pressure during respiration, and the passive relaxation of ventricle during diastole.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of the Frank-Starling Law of the Heart

Ribarič

Kordaš

2012

Computational and Mathematical Methods in Medicine

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We developed a lumped parameter, computer-based model of an equivalent electronic circuit for a one-atrium one-ventricle (frog) heart attached to a vascular circuit, to simulate a basic concept of cardiovascular physiology, the Frank-Starling Law of the Heart. A series of simulations was performed, to observe changes in cardiovascular variables (e.g., arterial pressure, ventricular volume, and valve flows) if either preload or afterload was increased. The simulated data agreed qualitatively, and quantitatively when experimental data are available, with data obtained on amphibian or on mammalian myocardium. In addition, the data obtained in these simulations improve our understanding of the mechanism(s) whereby the heart muscle adapts itself to increased distension (increased preload) or to impeded systolic contraction (increased afterload). The analysis of the measured valve flows suggests that the ventricle is a highly input sensitive pump because the input pressure determines the diastolic distension and, consequently, the force of ventricular systolic contraction. On the other hand, the ventricle is a relatively output insensitive pump. Therefore, not only atrium contraction, but also predominantly the preceding ventricular systolic contraction is the main mechanism of the subsequent diastolic ventricular filling. We conclude that the presented model enables the study of basic concepts of cardiovascular physiology.

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Section: Discussionmentioning

confidence: 99%

The “systemic” circuit is made up by a chain of resistor/capacitor segments.

…”

Section: Methodsmentioning

confidence: 99%

“…[18, 19]). The corresponding mitral and aortic flow is measured as a voltage drop across the 1 Ω resistor (Figure 2) as described [18, 19]. …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of the Frank-Starling Law of the Heart

Ribarič

Kordaš

2012

Computational and Mathematical Methods in Medicine

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“…The lumped-parameter computer model of this cardiovascular system was based on equivalent electronic circuits (EECs). For the presented study we upgraded an existing EEC model of the cardiovascular system with AVS [14–16]. The upgraded model, for simulating exertional syncope in a patient with AVS, includes

an improved subcircuit controlling ventricular contractility that gives an ejection fraction value of 70% for a normal heart;

a heart model with severe AVS, moderately decreased left ventricular contractility, and systolic insufficiency (as a complication of compensatory ventricular hypertrophy).

…”

Section: Introductionmentioning

confidence: 99%

Simulation of Exercise-Induced Syncope in a Heart Model with Severe Aortic Valve Stenosis

Sever

Ribarič

Kordaš

2012

Computational and Mathematical Methods in Medicine

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Severe aortic valve stenosis (AVS) can cause an exercise-induced reflex syncope (RS). The precise mechanism of this syncope is not known. The changes in hemodynamics are variable, including arrhythmias and myocardial ischemia, and one of the few consistent changes is a sudden fall in systemic and pulmonary arterial pressures (suggesting a reduced vascular resistance) followed by a decline in heart rate. The contribution of the cardioinhibitory and vasodepressor components of the RS to hemodynamics was evaluated by a computer model. This lumped-parameter computer simulation was based on equivalent electronic circuits (EECs) that reflect the hemodynamic conditions of a heart with severe AVS and a concomitantly decreased contractility as a long-term detrimental consequence of compensatory left ventricular hypertrophy. In addition, the EECs model simulated the resetting of the sympathetic nervous tone in the heart and systemic circuit during exercise and exercise-induced syncope, the fluctuating intra-thoracic pressure during respiration, and the passive relaxation of ventricle during diastole. The results of this simulation were consistent with the published case reports of exertional syncope in patients with AVS. The value of the EEC model is its ability to quantify the effect of a selective and gradable change in heart rate, ventricular contractility, or systemic vascular resistance on the hemodynamics during an exertional syncope in patients with severe AVS.

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Analog Simulation of Aortic Stenosis

Cited by 2 publications

References 25 publications

Simulation of the Frank-Starling Law of the Heart

Simulation of the Frank-Starling Law of the Heart

Simulation of Exercise-Induced Syncope in a Heart Model with Severe Aortic Valve Stenosis

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