An alarming report by WHO states that ischemic heart disease was the leading cause of death in the year 2021 among Indians, next to COVID-19. Restriction of blood flow in coronary arteries causes ischemic heart disease. Cholesterol, lipoprotein and calcium accumulate in the arteries forming plaque, narrowing the arteries and restricting blood flow. Blood pressure increases, leading to cardiovascular diseases such as hypertension and heart attacks. Regulating blood flow and pressure in the blocked arteries can help avoid lethal consequences.
A recent study by researchers from the Indian Institute of Technology Bombay (IIT Bombay) showed that magnetic fields can effectively manipulate blood flow, making blood flow faster or slower depending on field direction. The finding opens up possibilities for using magnets in heart disease treatments and provides insights for creating advanced drug delivery systems.
The researchers used a computation framework to simulate and analyse the blood flow pattern. They consider factors such as flow speed (velocity), pressure, and frictional force within the artery walls (wall shear stress).
“Wall shear stress (WSS) is the force per unit area exerted by the blood flow along the inner walls of blood vessels. It is a critical factor in vascular health, as abnormal WSS can contribute to the development of diseases like atherosclerosis. WSS is influenced by the blood's velocity and viscosity along the vessel walls”, says Prof. Abhijeet Kumar, who led the study at the Department of Mechanical Engineering, IIT Bombay.
The researchers devised a numerical model of a blocked artery and studied the influence of magnetic fields in the narrowed arteries using mathematical equations. The magnetic field interacts with iron-rich haemoglobin in the blood and impacts the blood flow depending on the direction of the magnetic field. The researchers calculated the motion of blood (using Navier-Stokes equations), analysed electromagnetic fields (using Maxwell’s equation) and monitored blood thickness or viscosity and flow (using the Carreau-Yasuda Model).
The researchers modelled different stages of narrowed arteries- mild-25 % blocked, moderate-35 % blocked, and severe-50 % blocked with varied shapes. The arteries are either evenly narrowed (axisymmetric), off-centric (eccentric), asymmetric, or sharp-edged. Axisymmetric and sharp-edged blockages caused the most severe pressure fluctuation and obstructed smooth blood flow. When the researchers applied the magnetic field parallel to the blood flow, they observed an increased blood flow speed. When they used the magnetic field perpendicular to the blood flow, there was a decrease in the flow speed.
Computational simulations showed that the magnetic field increased the blood flow by about 17%, 30% and 60% in mild, moderate, and severely blocked arteries. Stronger magnetic fields facilitated smoother blood flow. Magnetic field orientation that aligns with the blood flow reduces the pressure near the blockage in the severely stenotic (abnormally constricted) artery. Pressure fluctuations create more shear stress on the plaques (accumulated mass that causes the block), increasing the risk of rupture. The study found that magnetic force stabilises flow and pressure fluctuations in all the stenosis shapes, reducing the risk of plaque rupture.
The findings of the study would help treat patients with hypertension. The results show that the magnetic field influences blood flow, pressure, and wall shear stress. This can further help control high blood pressure and prevent damage to arterial walls. The study underlines the importance of magnets in cardiovascular therapies and enhanced patient care. It also highlights possible developments in innovative drug delivery systems using magnets.
“High and ultrahigh magnetic fields have shown both positive and adverse effects in experimental models, suggesting that safety evaluations are crucial before clinical application… Given the complexities and challenges mentioned, including the need for extensive research, clinical trials, and regulatory approvals, it might take several years before such treatments become widely available,” reminds Prof. Kumar.
The researchers recommend further study, including more realistic models to understand the flexibility and shear stress of a real arterial wall.
“The challenges in transforming this research into practical treatments include the complex interactions between magnetic fields and biological tissues, which can impact cellular structures, blood viscosity, and vessel walls. There is a need for careful evaluation to ensure safety and efficacy,” signs off Prof. Kumar.