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A mathematical analysis of hemorheological changes during heart valve replacement
1Department of Thoracic and Cardiovascular Surgery, Sahlgrenska University Hospital, Gothenburg University, Sweden.
Background:
This study was carried out to establish a mathematical model in order to assess blood trauma and hemorheology during cardiopulmonary bypass and heart valve replacement.
Methods:
Ten factors which represented blood trauma and hemorheology were investigated in fourteen patients undergoing mechanical heart valve replacement.
Results:
The results confirmed that red blood cell damage was mainly dependent on cardiopulmonary bypass time and hematocrit level. Platelet aggregation was influenced by platelet count, plasma fibrinogen and cardiopulmonary bypass time, the cases with aortic valve replacement resulting in more platelet activation than the mitral valve replacement (p<0.05). High shear blood viscosity was significantly influenced by hematocrit, plasma viscosity and red cell filterability, while low shear blood viscosity was significantly related to hematocrit, plasma viscosity and fibrinogen concentration, which represented 68.5% and 74.8% of hemorheologic changes due to blood trauma respectively.
Conclusions:
The relationship between blood trauma and hemorheologic changes was evaluated and the potential areas for improvements in cardiopulmonary bypass techniques in relation to mechanical heart valve implantation were identified. These areas of technical and pharmacological development must reduce changes in all the possible plasma components especially fibrinogen and also preserve platelets and red cells from damage.