Este vorba de o cateterizare cardiacă. Una dintre metode presupune introducerea cateterului (pe căile cunoscute, artera radială dreaptă sau stângă, sau artera femurală, cu avantajele și dezavantajele fiecăreia, a se vedea referințele) și măsurarea de două ori a presiunii, implicând RETRAGEREA cateterului pentru a doua măsurătoare.
Iată referințele și logica răspunsului:

https://citoday.com/articles/2019-mar-apr/simultaneous-measu...
“Cardiac Catheterization .Cardiac catheterization assists in determining the severity of a valvular stenosis by directly measuring the pressure gradient and flow across the valve. In patients with aortic stenosis, a true transvalvular pressure gradient is strongly recommended before valve replacement.
Any catheter designed for ventricular entry can obtain a left ventriculogram and measure the pressure within the left ventricle (LV). However, the Langston Dual Lumen Catheter can simultaneously measure the pressure in the aorta and the LV.
There are several ways that a PRESSURE GRADIENT may be measured across the aortic valve in a catheterization procedure:
Pullback method. A single-lumen pigtail catheter first measures the LV pressure before a “pullback” of the catheter into the aorta to measure the pressure in the aorta. Measurement is not simultaneous because each is taken during different cardiac beats, which can change the pressures. “
https://www.ncbi.nlm.nih.gov/pubmed/1550005
“This study was done to assess the accuracy of various techniques of measuring the pressure gradient and valve area in patients with aortic stenosis (AS). In 18 patients with AS, the pressure gradient was quantitated from (1) SIMULTANEOUS left ventricular and ascending aortic pressures (LV-AO), (2) nonsimultaneous LV-AO PULLBACK, (3) LV and femoral arterial (FA) pressures unadjusted for the time delay of the FA tracing (LV-FA unadjusted), and (4) LV-FA adjusted for time delay.”
https://www.ncbi.nlm.nih.gov/pubmed/22422735
“OBJECTIVES:
The aim of the study was to evaluate if the left radial approach (LRA) confers any additional advantage compared to the right radial approach (RRA) in octogenarian patients who undergo a coronary diagnostic procedure.
BACKGROUND:
Octogenarians, an increasing segment of patients in our society, present a higher risk of access-site complications related to invasive coronary catheterization. Transradial approach has been shown to be an effective alternative to reduce vascular complications. Although some studies have suggested that elderly people might benefit from a LRA, the advantages of using the left or right radial access remain not clear.”
https://citoday.com/articles/2012-may-june/right-versus-left...
“CONCLUSION With appropriate patient assessment and preparation, the right and left routes to transradial catheterization are equally safe and effective. To be proficient with both approaches, the operator needs to understand the differences between these two routes in terms of patient preparation, procedural technique, catheter selection, and laboratory setup. It is recommended that each cardiac catheterization laboratory develop specific protocols for right and left radial access to enhance the efficiency and likelihood of successful outcomes from transradial procedures.”
https://www.texasheart.org/heart-health/heart-information-ce...
“Cardiac catheterization is a method doctors use to perform many tests and procedures for diagnosing and treating coronary artery disease. The method involves threading a long, thin tube (called a catheter) through an artery or vein in the leg or arm and into the heart.”
Radial or femoral… choice and details are specified in the above article…
https://www.cathlabdigest.com/articles/Ask-Clinical-Instruct...
“Left Ventricle to Aorta PULLBACK
This is the most common method for valve analysis in the cath lab. After a left ventriculogram, the catheter can be pulled back sharply into the aorta. Staff would then look at the peak-to-peak comparisons to see if there is a difference (gradient) between the two. A problem can occur when a valve is potentially bad and the orifice of the valve can be very small, which can make the passage of a wire and catheter very difficult and time-consuming.”

https://www.romedic.ro/stenoza-aortica
“Atunci cind valvele aortice devin stenotice apare rezistenta la ejectia sistolica si se dezvolta un GRADIENT DE PRESIUNE sistolica intre ventriculul sting si aorta. Acest fapt conduce la incarcarea presionala a ventriculului sting care in timp determina cresterea grosimii peretelui ventricular (hipertrofia concentrica).”
“Tulburarile hemodinamice apar cind orificiul este redus cu o treime din dimensiunile sale normale, cind se dezvolta un GRADIENT PRESIONAL sistolic intre ventriculul sting si aorta. Presiunile ventriculului sting si ale aortei normale sunt aproximativ egale in timpul sistolei. La pacientii cu stenoza aortica presiunea intracavitara a ventriculului sting creste peste cea aortica pentru a produce impingerea singelui prin valvele aortice stenotice”
https://proceduri.romedic.ro/valvuloplastia-percutana-cu-bal...
“CATETERUL ESTE APOI RETRAS iar septul interatrial este dilatat printr-un balonas periferic de angioplastie cu diametrul de 6-8 mm. La final se avanseaza baloanele de valvotomie (diametrul 15-20 mm) de-a lungul firelor de ghidaj si pozitionate de-a lungul valvei.”
P.S. Am asistat în persoană ca interpret la multiple proceduri ca aceasta. Foarte reale...90% interpret...în persoană.