Anatomically detailed computational system for the arterial and venous circulatory systems.

The development of the modeling of the venous system is not solely motivated by medical concerns connected to venous pathologies. There are basic questions of human physiology and pathophysiology that could be better understood with models that include a precise description of the venous system. Relevant examples are (i) the effect of gravity in cerebral blood flow, of relevance for the understanding of human physiology, as well as for the study of extreme conditions related to aerospace research; (ii) the role played by the various compartments such as arteries, veins and microcirculation tissue and pulsation of the cerebrospinal fluid in intracranial pressure; (iii) the role of blood absorption, filtration and return in the physiology of the kidney, with strong implications for the study of hypertension. These aspects constitute a strong motivation to direct efforts to bring the level of complexity of models of the venous system at the same level currently achieved by its arterial counterpart, the ADAN model (Anatomically Detailed Arterial Network, http://hemolab.lncc.br/adan-web), developed by the INCT-MACC, particularly by the HeMoLab.

Impact

The low pressure existing in this part of the human CVS requires a new and much more advanced mathematical-numerical treatment than that used for the study of arterial circulation. Besides the significant impact of this scientific-technical knowledge area, the availability of a complete computational model of the human CVS (arterial, venous, pulmonary and heart - including the behavior of the atria, ventricles and valves - circulation) enables a better understanding of microcirculation in tissues and organs (such as heart, liver, kidney, among others) in normal conditions or in conditions altered by disease, thus helping in the diagnosis, treatment and surgical planning. Moreover, it must be noted that there is no other group in the international community working in the construction of a venous model as the one proposed in this part of the project. Thus, another impact will be to maintain Brazil as the main interlocutor in this area of knowledge.

Methodologies for testing the computer system

The level of detail of the venous network will be achieved the employment of the same methodology used in the construction of the arterial network of the ADAN model. Moreover, medical images provided by ALs such as ICES, the Incor and the Brigadeiro Hospital will be used. After the construction of a closed system incorporating models for the heart chambers and valves, the outputs of the computer system will be compared with measurements of pressure and blood flow in various venous districts obtained during routine procedures performed at the above-mentioned medical centers.

Specifications and results to be provided by the computer system

• Three-dimensional location within the human body of all arteries and veins reported in the medical literature.
• Detailed morphometric information of the vessels proximal and distal lumen diameters, length and wall thickness.
• Mechanical properties of tissues (elastin, collagen and smooth muscle) that make up the wall of all vessels incorporated in the model.
• Detailed information of pressure and blood flow during each cardiac cycle for every district of the human CVS.
• If coupled to the structure of arterial beds (arterioles, capillaries and venules), the system will provide detailed information of the microcirculation (pressure and blood flow) incorporating effects of collateral circulation by anastomosis.
• Study of blood flow in normal conditions and in situations altered by medical procedures and/or diseases in any part of human CVS.
• Patient-specific customization of the model.
• Providing access to and customization of the computer system through web (Science gateways) interfaces.