Ultrasound Guidance Enters Direct Competition With Conventional Distal Radial Puncture
A new randomized pilot trial is taking aim at one of the most persistent bottlenecks in transradial coronary access: failure to cannulate the distal radial artery. The Sound Distal study is comparing echo-guided puncture with conventional palpation-based puncture in adults undergoing diagnostic angiography or PCI, with first-wiring pass success as the primary endpoint.
The rationale is straightforward. Distal radial access has gained traction because it can reduce vascular complications and proximal radial artery occlusion, but the technique is constrained by anatomy. The distal vessel is smaller, its course varies from patient to patient, and blind puncture can become a time-consuming exercise in repeated attempts. In a procedure where vascular access sets the pace for the entire case, failure at the skin level can ripple into delays, crossover, bleeding, and operator frustration.
This trial is built around that problem rather than around a broader pharmacologic question or a downstream ischemic endpoint. It isolates the access step itself and asks whether imaging the artery before puncture can improve the odds of success on the first wiring pass, the point at which a needle, wire, and sheath strategy either moves cleanly forward or stalls.
A Trial Designed Around the Access Problem Itself
CHU Helora Jolimont is sponsoring the study, which is being conducted in Belgium at CHU HELORA – Hôpital de Jolimont in La Louvière. The trial is interventional, randomized, parallel-group, and open label. Enrollment reached 600 participants, all adults 18 years and older who required diagnostic angiography or PCI and had stable or acute coronary syndrome, or a positive functional study documenting ischemia.
Participants had to be eligible for PCI and able to consent. Women who were pregnant or breastfeeding were excluded, as were patients expecting major surgical intervention at the vascular access site within six months, those with prior participation in the study, and those with recent stroke, transient ischemic neurological attack, cerebrovascular accident, or known intracranial pathology such as mass, arteriovenous malformation, or aneurysm.
The intervention is procedural rather than pharmacologic, but the clinical stakes are familiar to every cath lab team. Ultrasound can reveal the vessel’s caliber, depth, and course before the needle enters the skin. That matters in the distal radial segment, where palpation alone may be unreliable and anatomy can quickly turn hostile. A successful image-guided approach may reduce the number of punctures, shorten access time, and lower the chance of crossover to another access strategy.
First-Wiring Pass Success Is the Central Test
The primary outcome is the first-wiring pass success rate, measured from the start of the procedure to its end. This endpoint is practical because it reflects more than a simple skin puncture. It captures whether the operator can obtain arterial entry and wire the vessel without repeated failed attempts, a metric that blends technical precision with procedural efficiency.
A first-pass result carries downstream implications even before the procedure ends. Fewer failed punctures usually mean less local trauma, less bleeding, and less operator time spent troubleshooting the access site. In distal radial work, where the artery is smaller and more variable than the conventional radial site, those differences may be especially meaningful.
The secondary outcomes push further into the mechanics of access quality. Investigators are measuring total number of attempts, time to access, bleeding graded by EASY criteria and BARC criteria, successful sheath insertion, crossover to ultrasound guidance and/or access site crossover, vascular access-site complications, distal radial artery occlusion, hemostasis time, and pain associated with the procedure. Those measures will help show whether ultrasound changes not just success rates, but the overall texture of the encounter for both patient and operator.
One sentence captures the clinical question cleanly: imaging either removes uncertainty, or it does not.
Why Ultrasound Could Change Distal Radial Access
The biological rationale is not complicated, but it is important. Distal radial access is attractive because it preserves proximal radial patency and may limit access-related complications, yet the same anatomy that makes it appealing also makes it harder to enter reliably. Ultrasound may improve puncture accuracy by identifying the optimal entry point, clarifying vessel size, and avoiding areas where the artery is too small or anatomically unfavorable.
A specific ultrasound algorithm for distal radial puncture has already been developed and used in routine clinical practice at the sponsoring center, with success in a selected group of patients who had favorable anatomic features. The Sound Distal trial now extends that concept into a direct randomized comparison against conventional puncture. The trial is also probing reproducibility among operators, a critical issue because access techniques that work well in the hands of one expert can become less dependable when scaled across a broader cath lab team.
The decision to include pain, hemostasis time, and bleeding endpoints reflects a broader procedural truth. Success in vascular access is not merely a binary event. A case that eventually succeeds after multiple punctures can still leave the patient with more discomfort, more local bruising, and a longer road to hemostasis than a single clean pass.
What the Completed Study Will Need to Show
The study started on 2024-11-18 and reached primary completion and study completion on 2026-11-01. No results are posted yet, so the trial’s real value remains prospective. Its design suggests a careful attempt to answer a question that has moved into daily practice faster than the evidence base has fully caught up with it.
If ultrasound guidance delivers a materially higher first-wiring pass success rate, the implications would be immediate at the bedside. Cath lab teams could justify more routine prepuncture imaging for distal radial access, especially in patients with challenging anatomy or where repeated blind attempts would be especially undesirable. If the benefit proves modest, the added time and equipment burden of imaging may not be justified for every case, and conventional puncture would retain a larger role.
The study’s completion is only the beginning of the interpretation. What matters next is whether a cleaner puncture translates into fewer attempts, faster access, less bleeding, and lower occlusion rates without introducing new delays or workflow friction. Those are the endpoints that determine whether an access technique stays in the training room or becomes part of routine coronary practice.
For now, the trial stands as a focused test of a simple proposition: in distal radial PCI, seeing the artery before puncturing it may be the difference between an elegant first pass and a cascade of avoidable failures.