Patients undergoing RHC at the Denver Health Medical Center from 12/20/2022–3/1/2023 underwent VExUS examination immediately prior to RHC. VExUS examinations were conducted and graded as previously described.12 Patients were reclined at 45 degrees. The ultrasonographer first measured the IVC diameter approximately 3–4 cm from the junction of the IVC and the right atrium, or 1–2 cm caudal to the confluence of the hepatic vein and the IVC. Hepatic vein pulsatility was assessed by placing the probe in either a subxiphoid or lateral view, and placing the doppler gate across any of the hepatic veins and observing doppler waveforms. Hepatic portal venous pulsatility was assessed similarly, by placing the doppler gate across the portal vein and observing the pulsatility index: (Vmax – Vmin)/Vmax. Renal vasculature was visualized with the probe in the posterior axillary line, with the doppler gate placed to detect the flow of the interlobar or arcuate renal veins in the renal cortex, outside the hilum of the kidney. VExUS exams were conducted using the Mindray TE7 system (Mindray Bio-Medical Electronics Co).
Vexus Scoring:
As previously described, the VExUS score is composed of evaluations of the IVC, hepatic vein, portal vein, and renal vasculature.12 if a patient’s IVC diameter is < 2 cm, the exam is assigned a score of 0. In the presence of an IVC ≥ 2 cm, the examiner proceeds with the exam, categorizing each vein as either normal, mildly abnormal, or severely abnormal. For purposes of this study, all views were acquired in all patients scanned.
Hepatic Vein: Normal hepatic vein doppler waveforms show a small, retrograde a-wave, followed by anterograde S and D waves, with the ratio of amplitudes of the S to D waves being > 1. In increasing states of congestion, the S wave shrinks relative to the D wave before `reversing entirely, becoming retrograde. A S:D ratio > 1 is normal, a S:D ratio ≤ 1 is mildly abnormal, and a reversal of the S wave is severely abnormal.
Portal Vein: A normal portal vein doppler waveform shows minimal pulsatility, with a pulsatility index < 30%. A pulsatility index of 30–49% is mildly abnormal, and a pulsatility index > 50% is severely abnormal.
Renal Vasculature: A normal renal doppler pattern shows arterial pulsations generating regular retrograde peaks, and renal veins generating a continuous, smooth anterograde flow. As venous congestion increases, venous pulsations become visible, creating anterograde pulsations observable during systole and diastole, and eventually, only diastole. A smooth venous baseline is considered normal. Biphasic anterograde pulsations reflecting systole and diastole are considered mildly abnormal, and monophasic pulsation, corresponding only with diastole is considered severely abnormal.
Any combination of normal or mildly abnormal scores is given a grade of 1. If the patient has one severely abnormal score, they are given a grade of two. Two or more severely abnormal scores results in a grade of 3, reflecting severe congestion.
Ultrasonographers were internal and emergency medicine residents with institutional training in ultrasound and video instruction in VExUS by the developers of the technique. VExUS results were graded and recorded before publication of RHC results, and investigators were blinded to the outcome of RAP at the time of VExUS assessment and grading. Data were manually extracted from patient charts, including past medical history, demographic information, and pertinent laboratory and imaging results. Patients in whom VExUS exams could not be completed or interpreted due to poor image quality, or whose RHC were not completed were excluded. Multivariable linear regression was used to assess the relationship between VExUS and RAP, controlling for age, sex, and Charlson Comorbidity Index (CCI).14 Receiver operating characteristic curves were constructed for both VExUS grade and IVC diameter for identification of RAP ≥ 12 mmHg.