Translesional PRESSURE Measurements to Assess Clinical Relevance of a Mesenteric Artery Stenosis (PRESSURE-study)

Chronic mesenteric ischemia (CMI) is an incapacitating disease with a vast impact on quality of life due to severe abdominal pain after a meal, resulting in fear of eating and subsequent severe weight loss. CMI has an incidence of 9.2 per 100,000, which increases with age to up to 44.3 per 100,000 in persons of ≥80 years. These incidence rates are higher than the incidence rates of other more well-known diseases, such as esophageal cancer (4.3 per 100,000) or ruptured abdominal aortic aneurysms (7.0 per 100,000), and even approximates the incidence of Crohn's disease (10.9 per 100,000). The prevalence of atherosclerotic mesenteric artery stenosis, the leading cause of CMI, is even higher (6-29%). An extensive collateral circulation protects the gut against ischemia in the majority of patients. Hence, not all mesenteric artery stenoses result in CMI and only those stenoses that are hemodynamically significant should be treated. Treatment decisions for atherosclerotic CMI are currently based on history, stenosis severity on imaging, and signs of mesenteric ischemia during a functional test. However, sufficiency of the collateral circulation cannot be assessed, resulting in substantial failure of patient-reported symptom relief after stent placement (27-31% in single vessel disease), unnecessary complications and avoidable healthcare expenses.

The Dutch Mesenteric Ischemia Study group (DMIS) consists of experts in the field of CMI and aims to improve both the quality of care and the quality of life of CMI patients by initiating and designing studies to provide patient-centered and evidence-based solutions to pending challenges in the field of CMI. In recent years the DMIS has been searching for a reliable tool to assess hemodynamic significance of a mesenteric artery stenosis, while accounting for the collateral circulation, in order to guide treatment decisions and avoid clinically unbeneficial revascularization procedures. In a retrospective study flow velocities were increased in the unaffected mesenteric artery when either the CA or SMA were stenosed. The increased blood flow in the unaffected vessel could indicate a well-functioning collateral network where blood flow is rerouted to prevent chronic mesenteric ischemia.

Another retrospective cohort study reports that intra-arterial pressure measurements, using a 4Fr catheter, could predict clinical success of mesenteric artery revascularization with an 86% sensitivity and 83% specificity. In this retrospective study, pressure gradients were obtained after administration of a vasodilator. With these pressure measurements, the Pd/Pa ratio and the fractional flow reserve (FFR) were measured. The Pd/Pa ratio is the pressure distal to the stenosis divided by pressure in the aorta and the FFR is the Pd/Pa ratio under hyperemic conditions, after administration of a vasodilator. Mesenteric artery pressure measurements could be a promising tool for the assessment of hemodynamic and clinical relevance of mesenteric artery stenosis, since pressure gradients will only occur in mesenteric arteries with a severe stenosis and an insufficient collateral circulation.

The previously performed retrospective study yielded promising results, but had some methodological limitations. Pressure measurements in the conducted study were only obtained in a subset of CMI patients by the decision of the interventional radiologist, with pressure measurements in general only performed when the radiologist was in doubt about the significance of the stenosis. This could have potentially led to selection bias and makes reproducibility of this study difficult to the general population of CMI patients as a whole. In the proposed study, the investigator will perform pressure measurements in the general population of CMI patients with a consensus diagnosis of CMI who are scheduled for endovascular treatment, hypothesizing that stenosis grade (%) alone cannot predict hemodynamic significance accurately. By obtaining pressure measurements in all CMI patients, including borderline, high-grade stenoses and occlusions, the investigators aim to evaluate the (in)sufficiency of the mesenteric collateral network by measuring pressure gradients over the stenotic lesion. The investigators hope such pressure gradients can predict clinical treatment success for all CMI patients. If positive results are obtained in this study, the investigators hope these measurements can serve as a decision-making tool in suspected CMI patients (to stent or not to stent).

In an in-vitro study (currently under submission) in which postprandial states in the superior mesenteric artery (SMA) and celiac artery (CA) were simulated, pressure measurements were obtained using a 4Fr macrocatheter, microcatheter and pressure wire. It showed that especially for a stenosis ≥75% or a longer stenosis, the 4Fr catheter tended to overestimate the fractional flow reserve (FFR) when compared to the microcatheter, due to partial obstruction of the residual vessel lumen by the relatively large size of the 4Fr catheter compared to microcatheter or pressure wire. Taking this into consideration together with a wider applicability and lower costs, they recommended the microcatheter for clinical use.