<aside> 🎓 Skills Learned:
High blood pressure can be described as a silent killer as it degrades the blood vessel walls slowly and the damage is not seen until more dangerous conditions are expressed, such as stroke and heart failure. This strain on the blood vessels will cause major damage to the heart itself, but one shouldn’t forget that individual organs will be affected greatly as well. The interest in this project was the effect hypertension has on the brain. Knowing that the brain requires a lot of blood, restricting blood flow to this vital organ would be deadly. To form a better understanding of how hypertension affects the brain, 2 simulations were conducted for 2 models using ANSYS Computational Fluid Dynamics software. The first model was meant to represent an artery in the brain, specifically the prefrontal artery, that has normal blood pressure. The second model represent a prefrontal artery that has hypertension. The boundary conditions were obtained from a study on the blood flow in cerebral arteries. After the simulations were conducted, it was found that the model with hypertension had higher values of pressure as well as shear strain rate acting on the artery walls compared to the model of a healthy artery.
The geometry of arteries in the prefrontal cortex was be modeled in the ANSYS CFD software. To be able to clearly see the behavior of fluid within the model, the diameter was 0.962 mm, and the length was greatly increased so that the inlet behavior can be clearly analyzed. Since an artery of smaller size is of interest, it was safe to assume the blood would have Newtonian behavior therefore water was the material of choice. The reference pressure was at 1 atm, the heat transfer model was thermal energy, and the turbulence model used was the medium intensity 5% option. The no-slip condition was assumed at the walls.
Two models had different inlet and outlet conditions, based on researched values. For the model that represents a person without hypertension, the mass flow rate at the inlet was 0.0544 L/min (0.000907 kg/s), and the outlet modeled systolic pressure at 95 mmHg. For the model that represents a person with hypertension, the mass flow rate at the inlet was 0.0618 L/min (0.001030 kg/s) and the outlet also modeled systolic pressure at 160 mmHg.
The first simulation demonstrated the behavior of blood within the prefrontal arteries of someone without hypertension. The shear strain rate at the inlet was quite high with a value of 5.45710^3 s^-1 and it remained that high near the walls throughout the whole artery. Next, a second simulation was done to model the behavior of blood within the prefrontal arteries of someone with hypertension. In the hypertension model, the shear strain rate increased to 1.08210^4 s^-1.
Altogether, the shear strain rate against the walls of the arteries is higher in the model representing an artery with hypertension compared to a healthy artery without this condition. The results from these simulations proved that the increase in blood pressure from having hypertension will increase the shear stresses against the walls of the arteries and this will slowly wear them down. Also, with higher shear strain rate less blood is able to reach its destination because of this resistance therefore restricting blood flow to certain extremities.
Proving that hypertension may wear down the walls of blood vessels is an important fact to know because of the increase of more and more people unknowingly living with hypertension. Although it is a condition that may not be physically felt, people show pay attention to their cardiovascular health to prevent future complications that will show up externally as a result.