Patient-Specific Implant Techniques Could Reduce Stroke Risk in Patients with LVADs

For individuals with advanced heart failure, left ventricular assist devices (LVADs) can be life-saving. These implantable devices enhance blood circulation throughout the body and are often the final therapeutic option available for patients with severe heart failure. With over 14,000 people currently using them and heart failure affecting 26 million individuals worldwide, the use of LVADs is expected to rise. However, they are not without risks. Compared to the general population, people with LVADs face an 11% to 47% greater chance of developing blood clots that may travel to the brain and cause a stroke. The reason why some LVAD patients experience strokes while others do not remains unclear. A new study now points to hemodynamics—how blood flows through the body—as a possible explanation.

The body depends on a steady supply of oxygen-rich blood to function properly. Heart failure arises when the heart is no longer able to pump enough blood to meet the body's needs. Normally, during each heartbeat, the heart’s left ventricle contracts and sends blood into the arteries, delivering oxygen and nutrients to organs, muscles, and bones. In heart failure, the left ventricle weakens and loses its efficiency. An LVAD, which connects directly to the heart, bypasses this ventricle and pumps blood straight into the aorta, the body’s main artery. While LVADs can prolong and improve life, they also raise the likelihood of blood clots forming. When blood flow slows or stagnates—especially in areas like the left ventricle—it can lead to clot formation. These clots can then travel through major arteries, with the vessels supplying the brain being among the most critical. If a clot becomes lodged there, it can block or reduce blood flow to the brain, leading to a stroke.

Applying engineering principles such as fluid dynamics to medical questions can provide perspectives that traditional diagnostic tools may overlook. A team of engineers from the University of Colorado Boulder (Boulder, CO, USA), along with collaborators, conducted a study to investigate whether differences in blood flow among LVAD users could account for who develops strokes. They studied 12 LVAD patients—six who had experienced strokes after implantation and six who had not. Using detailed imaging data of the aorta, surrounding vessels, and the attached LVAD component, they constructed 3D digital models or “digital twins” of each patient. The team also incorporated each individual's clinical data, including heart rate and blood pressure, into the models. These simulations offered new insights into stroke mechanisms. The digital twins enabled the researchers to estimate how blood moved through each person’s aorta and to simulate how flow patterns might have looked before the LVAD implantation.

Their analysis revealed differences in blood flow between those who had strokes and those who did not—both before and after receiving their LVADs. They discovered that the LVADs altered blood flow in each case, creating a forceful “jet” of blood that entered the aorta at an angle different from the natural flow produced by the heart. These altered flow dynamics could help explain why some patients are more susceptible to stroke. For example, some flow patterns may promote blood stagnation in specific areas, increasing the likelihood that platelets will adhere to protein networks in the blood and form clots. The study’s findings may lead to better treatment strategies and outcomes for patients with heart failure. With this knowledge, clinicians could tailor LVAD implantation procedures and post-operative monitoring to each patient. They might also be able to assess stroke risk more accurately and deliver more personalized treatments.

“Knowledge gained from this study can help us develop patient-specific implant techniques to reduce the likelihood of stroke in patients with durable LVADs,” said Professor Jay Pal, a co-author of the study.

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