VExUS and right ventricular to pulmonary artery uncoupling

Abstract

The VExUS score is meant to alert the clinician to an uncoupling at the right ventricular (RV)–pulmonary artery (PA) interface. Bedside ultrasonography and determination of the etiology of an abnormal VExUS score is the first step.

We would like to congratulate Dr. Guinot as one of the torchbearers of venous congestion, contributing greatly to the advancement of this relatively new field that deserves attention because of its clinical significance. As the authors of the original VExUS concept [1], we are mostly in agreement with Dr. Guinot’s conclusions. However, we would like to emphasize that this does not represent a paradigm shift, since the VExUS score was never designed—nor intended—to serve as a reflection of so-called “volume status.”

While it is undeniably true that some clinicians have attempted to use it in that quixotic quest for a simple “fuel gauge” of intravascular volume—a trend we have noted in a few publications—the original paper never suggested such an interpretation. The subsequent case series, designed to illustrate the diverse potential causes of elevated VExUS scores [2], and our article published last year on myths and misconceptions of VExUS [3], both highlighted clearly that venous congestion is not necessarily proportional to fluid accumulation.

Elements of the VExUS score such as portal vein Doppler pulsatility or more recently femoral venous Doppler velocity [4], have been associated with both right ventricular (RV) dysfunction but also pulmonary hypertension which in cardiac surgery has been associated with increased post-op complications [5, 6]. (Fig. 1). In fact, the VExUS score is meant to alert the clinician to an uncoupling at the RV–pulmonary artery (PA) interface (Fig. 2) [7]. This finding carries significant clinical importance, as it requires the clinician to determine the underlying cause of the uncoupling. Fluid removal for instance would not be indicated in the presence of pulmonary embolism even if there is portal pulsatility. Indeed, while volume overload may be a frequent culprit—particularly in patients with baseline congestive heart failure or in the context of overzealous fluid resuscitation—fluid removal is not always the appropriate response.

Fig. 1.

Hemodynamic parameters and portal vein velocity (PVV) in a 79 year-old woman (A, B) before and (C, D) after mitral valve and aortic valve replacement and tricuspid annuloplasty. Note theworsening in pulmonary hypertension using the MAP/MPAP ration that went from 5 to 3.48 [12] and the reduction in the TAPSE/ systolic Ppa as coupling indice [13]. Both elements were associated with worsening of portal pulsatility. Post-operatively the patient was reexplored for tamponade, developed acute kidney injury and prolonged duration of stay in the ICU. Abbreviations: CPB, cardiopulmonary bypass; MAP. Mean arterial pressure; MPAP, mean pulmonary artery pressure; Pfa, femoral arterial pressure; Ppa, pulmonary artery pressure; Pra, radial artery pressure; Prv, right ventricular pressure, TAPSE, tricuspid annular plane systolic velocity; Vmin, minimal velocity; Vmax, maximal velocity

Fig. 2.

Approach to the VExUS score. In the presence of abnormal VExUS score, history, labs, ECG and physical examination combined with POCUS or TEE as needed may provide the etiology. Abnormal VExUS score is the result of impaired coupling between RV contractility or ventricular elastance and pulmonary arterial afterload or arterial elastance. The two causes of an abnormal VExUS score is pulmonary hypertension (PHT) and RV failure or a combination of both. PHT can result from several mechanisms such as pre or post capillary for which the treatment will significantly differ. Similarly, RVF can result from ischemia which is worsened by RV dilatation. The role of the clinician is to identify the most likely mechanism(s) and identify the best personalized therapeutic approach which is not always fluid removal. Abbreviations: ECG, electrocardiogram; POCUS, point-of-care ultrasound; PA, pulmonary artery; PHT, pulmonary hypertension; RV, right ventricular; RVF, right ventricular failure; TEE, transesophageal echocardiography; VExUS, venous excess ultrasound score

As shown by Vonk Noordegraaf, progressive pulmonary hypertension will lead to RV hypertrophy, then RV dilatation followed by RV failure. Those changes will parallel the progressive deterioration in RV-PA coupling [8]. Those changes will be also accompanied by changes in RV pressure waveform from a normal RV horizontal slope, to an oblique and to a square-root sign with mid-diastolic opening of the pulmonic valve [9]. The later condition has been described in RV infarction [10]. Not surprisingly, the changes in RV pressure waveform will be associated in changes in right atrial pressure waveform and hepatic, splenic, renal and femoral venous Doppler velocities patterns [11]. Therefore it is not surprising that the VExUS score has been associated with RV-PA coupling [7].

In summary, as Dr. Guinot rightly points out, careful analytical work at the bedside is needed to identify the cause of venous congestion. This reality underscores that the VExUS score is not a tool for assessing volume status, but rather an alarm signal for venous congestion as a result of RV-PA uncoupling. Importantly, this does not constitute a paradigm shift; instead, it serves as a valuable reinforcement of principles we have been emphasizing for years.

Author contributions

P.R., W.B.S., K.H., R.S., and A.D. All authors contributed equally to all aspects of the work, approved the final version of the manuscript, and agree to be accountable for the accuracy and integrity of the work.

Funding

Not appliable.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not appliable.

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Competing interests

The authors declare no competing interests.