Theoretical analysis of rest and exercise hemodynamics in patients with total cavopulmonary connection

Department of Electronics, Computer Science and Systems, University of Bologna, 40136 Bologna, Italy.
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 04/2002; 282(3):H1018-34. DOI: 10.1152/ajpheart.00231.2001
Source: PubMed


The objective of this study was to determine the impact of a total cavopulmonary connection on the main hemodynamic quantities, both at rest and during exercise, when compared with normal biventricular circulation. The analysis was performed by means of a mathematical model of the cardiovascular system. The model incorporates the main parameters of systemic and pulmonary circulation, the pulsating heart, and the action of arterial and cardiopulmonary baroreflex mechanisms. Furthermore, the effect of changes in intrathoracic pressure on venous return is also incorporated. Finally, the response to moderate dynamic exercise is simulated, including the effect of a central command, local metabolic vasodilation, and the "muscle pump" mechanism. Simulations of resting conditions indicate that the action of baroreflex regulatory mechanisms alone can only partially compensate for the absence of the right heart. Cardiac output and mean systemic arterial pressure at rest show a large decrease compared with the normal subject. More acceptable hemodynamic quantity values are obtained by combining the action of regulatory mechanisms with a chronic change in parameters affecting mean filling pressure. With such changes assumed, simulations of the response to moderate exercise show that univentricular circulation exhibits a poor capacity to increase cardiac output and to sustain aerobic metabolism, especially when the oxygen consumption rate is increased above 1.2-1.3 l/min. The model ascribes the poor response to exercise in these patients to the incapacity to sustain venous return caused by the high resistance to venous return and/or to exhaustion of volume compensation reserve.

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Available from: Mauro Ursino, Jan 11, 2014
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    • "The total vascular compliance (í µí° ¶ sys ) and pulmonary vascular compliance (í µí° ¶ pul ) were set as a function of body weight by í µí° ¶ sys = 2.1 * weight [24] and í µí° ¶ pul = 0.408 * weight, respectively [25]. For other model parameters, such as systemic/pulmonary vascular resistances and cardiac elastances, although most of them are derivable from previous studies [26] [27] [28], there are significant discrepancies among the values used in different studies. Therefore, the model parameters were reassessed in the present study. "
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    ABSTRACT: The clinical benefits of the Fontan operation in treating single-ventricle defects have been well documented. However, perioperative mortality or morbidity remains a critical problem. The purpose of the present study was to identify the cardiovascular factors that dominate the transient hemodynamic changes upon the change of a bidirectional cavopulmonary (Glenn) anastomosis (BCPA) into a total cavopulmonary connection (TCPC). For this purpose, two computational models were constructed to represent, respectively, a single-ventricle circulation with a BCPA and that with a TCPC. A series of model-based simulations were carried out to quantify the perioperative hemodynamic changes under various cardiovascular conditions. Obtained results indicated that the presence of a low pulmonary vascular resistance and/or a low lower-body vascular resistance is beneficial to the increase in transpulmonary flow upon the BCPA to TCPC change. Moreover, it was found that ventricular diastolic dysfunction and mitral valve regurgitation, despite being well-known risk factors for poor postoperative outcomes, do not cause a considerable perioperative reduction in transpulmonary flow. The findings may help physicians to assess the perioperative risk of the TCPC surgery based on preoperative measurement of cardiovascular function.
    The Scientific World Journal 11/2013; 2013(3):486815. DOI:10.1155/2013/486815 · 1.73 Impact Factor
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    • "Voluntary moderate and heavy exercise levels were simulated with vasodilation of peripheral vasculature and offsets to the efferent sympathetic (f ev in (2)) and vagal neural pathways (f es in (3)) feeding into the baroreflex [6],[10]. The offsets, in the form of ramp inputs lasting 5 seconds before reaching their target values listed in Table 2, mimic the commands from the central nervous system at the onset of different exercise levels and trigger the baroreflex intro preparing the circulatory system to accommodate the physiological demand. "
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    American Control Conference, 2008; 07/2008
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    • "For a healthy person, the baroreflex regulates the blood pressure and cardiac output according to different physiological states of the body by adjusting the heart rate, systemic vascular resistance, heart contractility and total blood volume. The main purpose of this paper is to examine, from a system perspective, the behavior of a model which combines the cardiovascular model of [1] [2] with the baroreflex model of [3] [4] [5]. This paper is organized as follows. "
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    American Control Conference, 2006; 07/2006
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