Transthoracic echocardiography (TTE) is the current standard of care to screen for right-to-left shunts (RLS), a recognized risk factor for stroke. While this diagnostic is widely available and easy to perform, it has low sensitivity (approximately 45%) for the most common type of RLS, called a patent foramen ovale (PFO). New data show it does not detect the presence of PFO in many cases, which may lead to undiagnosed patients with RLS who are not receiving best medical management.

First described in the Journal of Neurosurgery in 1982, transcranial Doppler (TCD) ultrasound has been used worldwide as a safe, noninvasive means of screening for RLS, has a sensitivity for PFO of about 96%, and provides noninvasive, real-time measurements of cerebral hemodynamics.

While TCD can be a valuable tool for monitoring brain circulation, it is rarely used because of the specialized knowledge and lengthy training requirements needed to perform an exam. A trained healthcare professional must skillfully find the transtemporal window, locate the appropriate vessel based on position, angle, and depth, and then expertly interpret the signal. Thus, TCD expertise remains scarce and use is limited.

With the incorporation of modernized technology that leverages artificial intelligence (AI) and robotics, TCD has been brought into the 21st century. It can now be leveraged as a sophisticated diagnostic tool that healthcare professionals can use without rigorous training.

TCD Improves Identification of RLS

Clinical trial data presented at the American Heart Association 2022 International Stroke Conference assessed the use of robotics- and AI-assisted TCD—specifically the autonomous NovaGuide Intelligent Ultrasound—compared with TTE for RLS diagnosis. The multicenter, prospective, single-arm BUBL clinical trial enrolled adults who presented with neurological signs and symptoms that potentially indicated embolic stroke or transient ischemic attack. The five-degrees-of-freedom robotics component allows for each ultrasound probe to independently and autonomously scan the temporal area to find and optimize bilateral cerebrovascular signals. The primary outcome was the percent shunt detection rate relative to standard-of-care TTE.

Study results showed the robotics-assisted TCD was three times more likely to detect RLS in patients with presumed embolic strokes than TTE. Among 129 evaluable participants, the RLS detection rate was 64% with NovaGuide and 21% by TTE for a difference of 43%. Additionally, NovaGuide identified large RLS in 27% of participants (Spencer Logarithmic Scale ≥3), while TTE identified large RLS in only 10% of these cases for a difference of 17%. There were no serious adverse events in this trial.

Notably, the robotic TCD utilized in the clinical trial was operated by healthcare providers without TCD expertise. The data show that robotic TCD democratizes the technique, allowing more providers to help patients benefit from the sensitivity of TCD for RLS detection.

As healthcare evolves, we as healthcare professionals cannot hesitate to leverage new technology backed by solid clinical evidence. By incorporating robotics-assisted TCD into the “stroke workup,” particularly in centers that otherwise do not have TCD expertise available, we can potentially make significant improvements toward more accurately diagnosing the underlying cause of stroke and thereby providing best preventative treatments.