Multiparametric vs. Inferior Vena Cava-Based Estimation of Right Atrial Pressure

Head-to-Head Comparison of Hepatic Vein and Superior Vena Cava Flow Velocity Waveform Analyses for Predicting Elevated Right Atrial Pressure

OBJECTIVE

Blood flow in the hepatic veins and superior vena cava (SVC) reflects right heart filling; however, their Doppler profiles are often not identical, and no studies have compared their diagnostic efficacies. We aimed to determine which venous Doppler profile is reliable for detecting elevated right atrial pressure (RAP).

METHODS

In 193 patients with cardiovascular diseases who underwent cardiac catheterization within 2 d of echocardiography, the hepatic vein systolic filling fraction (HV-SFF) and the ratio of the peak systolic to diastolic forward velocities of the SVC (SVC-S/D) were measured. HV-SFF < 55% and SVC-S/D < 1.9 were regarded as elevated RAP. We also calculated the fibrosis 4 index (FIB-4) as a serum liver fibrosis marker.

RESULTS

HV-SFF and SVC-S/D were feasible in 177 (92%) and 173 (90%) patients, respectively. In the 161 patients in whom both venous Doppler waveforms could be measured, HV-SFF and SVC-S/D were inversely correlated with RAP (r = -0.350, p < 0.001; r = -0.430, p < 0.001, respectively). SVC-S/D > 1.9 showed a significantly higher diagnostic accuracy of RAP elevation compared with HV-SFF < 55% (area under the curve, 0.842 vs. 0.614, p < 0.001). Multivariate analyses showed that both FIB-4 (β = -0.211, p = 0.013) and mean RAP (β = -0.319, p < 0.001) were independent determinants of HV-SFF. In contrast, not FIB-4 but mean RAP (β = -0.471, p < 0.001) was an independent determinant of SVC-S/D. The diagnostic accuracy remained unchanged when HV-SFF < 55% was considered in conjunction with the estimated RAP based on the inferior vena cava morphology. Conversely, SVC-S/D showed an incremental diagnostic value over the estimated RAP.

CONCLUSIONS

SVC-S/D enabled a more accurate diagnosis of RAP elevation than HV-SFF.

Correlation between echocardiographic estimation of right atrial pressure and invasive measurement of central venous pressure in postoperative pediatric patients with congenital heart disease: a prospective observational study

BACKGROUND

Right atrial pressure plays a critical role as a hemodynamic parameter in diagnosing pulmonary hypertension and other cardiac diseases, as well as guiding the treatment and prognosis of various cardiac disorders. If there is no obstruction between the inferior or superior vena cava (SVC) as central veins and the right atrium, the pressures in these veins could be considered equal to the right atrial pressure. This study aimed to examine the correlation between echocardiographic methods for estimating right atrial pressure and invasive measurements of central venous pressure (CVPi) in infants and children with congenital heart disease during the 48 h after cardiac surgery and to establish regression equations for echocardiographic estimation of central venous pressure (CVPe).

RESULTS

We prospectively enrolled 43 infants and children, ranging in age from 6 months to 16 years, including 20 males and 23 females. We found a significant correlation between CVPi and the ratio of the maximal diameter of IVC to the maximal diameter of the descending aorta ratio (IVCmax/DAOmax) (r = 0.529, P < 0.001), SVCS/D velocity ratio (SVCS/D) (r = 0.462, P = 0.006), right atrial vertical diameter (RAVD) (r = 0.409, P = 0.01), area (r = 0.384, P = 0.014), and tricuspid valve A wave acceleration rate (TVAAR) (r = 0.315, P = 0.048). Multiple regression analysis yielded an equation for estimating central venous pressure using four parameters related to the IVC, SVC, tricuspid valve, and right atrium. The equation is as follows: estimated CVP = 4.36 + (2.35 × IVCmax/DAOmax) + (1.06 × SVCS/D) +  (0.059 × RAVD) + (0.001 × TVAAR). This equation is strongly correlated with CVPi (Pearson r = 0.698, P = 0.002).

CONCLUSIONS

The estimation of central venous pressure through a multi-parametric equation that included the ratio of the maximal diameter of the inferior vena cava to the maximal diameter of the descending aorta, the ratio of S to D velocity of the superior vena cava, the vertical diameter of the right atrium, and the acceleration rate of the A wave of the tricuspid valve demonstrated a robust correlation with invasively measured central venous pressure. To assess the accuracy of predicted pressures by this equation, further investigations are required to apply this innovative multi-parametric formula to a prospective population of pediatric patients with congenital heart disease.

Inferior vena cava ultrasound and other techniques for assessment of intravascular and extravascular volume: an update

Goals of volume management are to accurately assess intravascular and extravascular volume and predict response to volume administration, vasopressor support or volume removal. Data are reviewed that support the following: (i) Dynamic parameters reliably guide volume administration and may improve clinical outcomes compared with static parameters, but some are invasive or only validated with mechanical ventilation without spontaneous breathing. (ii) Ultrasound visualization of inferior vena cava (IVC) diameter variations with respiration reliably assesses intravascular volume and predicts volume responsiveness. (iii) Although physiology of IVC respiratory variations differs with mechanical ventilation and spontaneous breathing, the IVC collapsibility index (CI) and distensibility index are interconvertible. (iv) Prediction of volume responsiveness by IVC CI is comparable for mechanical ventilation and spontaneous breathing patients. (v) Respiratory variations of subclavian/proximal axillary and internal jugular veins by ultrasound are alternative sites, with comparable reliability. (vi) Data support clinical applicability of IVC CI to predict hypotension with anesthesia, guide ultrafiltration goals, predict dry weight, predict intra-dialytic hypotension and assess acute decompensated heart failure. (vii) IVC ultrasound may complement ultrasound of heart and lungs, and abdominal organs for venous congestion, for assessing and managing volume overload and deresuscitation, renal failure and shock. (viii) IVC ultrasound has limitations including inadequate visualization. Ultrasound data should always be interpreted in clinical context. Additional studies are required to further assess and validate the role of bedside ultrasonography in clinical care.

Inferior Vena Cava Edge Tracking Echocardiography: A Promising Tool with Applications in Multiple Clinical Settings

Ultrasound (US)-based measurements of the inferior vena cava (IVC) diameter are widely used to estimate right atrial pressure (RAP) in a variety of clinical settings. However, the correlation with invasively measured RAP along with the reproducibility of US-based IVC measurements is modest at best. In the present manuscript, we discuss the limitations of the current technique to estimate RAP through IVC US assessment and present a new promising tool developed by our research group, the automated IVC edge-to-edge tracking system, which has the potential to improve RAP assessment by transforming the current categorical classification (low, normal, high RAP) in a continuous and precise RAP estimation technique. Finally, we critically evaluate all the clinical settings in which this new tool could improve current practice.

Comparison of subclavian vein to inferior vena cava collapsibility by ultrasound in acute heart failure: A pilot study

BACKGROUND

Management of acute decompensated heart failure (ADHF) requires accurate assessment of relative intravascular volume, which may be technically challenging. Inferior vena cava (IVC) collapsibility with respiration reflects intravascular volume and right atrial pressure (RAP). Subclavian vein (SCV) collapsibility may provide an alternative.

HYPOTHESIS

The purpose of this study was to examine the relationship between SCV collapsibility index (CI) and IVC CI in ADHF.

METHODS

This was a prospective study of non-ventilated patients with ADHF who had paired IVC and SCV ultrasound assessments. As SCV CI is highly position-dependent, measurements were performed supine at 30-45°.

RESULTS

Thirty-three patients were included with 36 encounters. The sample size was adequately powered for receiver-operator characteristic (ROC) analysis. SCV CI correlated with IVC CI during relaxed breathing (R = .65, n = 36, p < .001) and forced inhalation (R = .47, n = 36, p = .0036). SCV CI < 22% and >33% corresponded to IVC CI < 20% and >50% suggesting hypervolemia (sensitivity/specificity: 72%) and hypovolemia (sensitivity/specificity: 78%), respectively. Moderate to severe tricuspid regurgitation (TR) compared to less than moderate TR was associated with lower SCV CI (medians: 12.4% vs. 25.3%, p = .022) and IVC CI (medians: 9.6% vs. 35.6%, p = .0012). SCV CI and IVC CI were not significantly different among chronic kidney disease stages.

CONCLUSION

In non-ventilated ADHF, SCV CI at 30-45° correlates with paired IVC CI, and may provide an alternative to IVC CI for assessment of relative intravascular volume, which may facilitate clinical management. Moderate to severe TR decreases SCV CI and IVC CI and may result in overestimation of relative intravascular volume.

Hypovolemic Status in Older Hip Fracture Patients Elucidated by Preoperative Transthoracic Echocardiography

Older patients undergoing hip fracture surgery often experience intraoperative hemodynamic instability despite maintaining cardiac function. Although preoperative hemodynamics in such patients have been demonstrated mainly through invasive monitoring, few studies have addressed hemodynamics based on noninvasively measured parameters. We aimed to investigate preoperative hemodynamic states in older hip fracture patients using transthoracic echocardiography (TTE). The TTE data of patients aged >75 years who underwent hip fracture surgery or elective total hip arthroplasty (THA) between April 1, 2019, and March 31, 2021, were collected. In addition to the baseline characteristics, the TTE data from hip fracture patients were compared with the data of those who underwent THA. The hip fracture patients (n = 167) were significantly older and had lower stroke volume (45.6 vs. 50.9 ml; p < 0.01) and stroke index (33.7 vs. 36.6 ml/m²; p < 0.01) compared to those who underwent elective THA (n = 44). However, the cardiac output (3.51 vs. 3.48 L/min; p=0.273) and cardiac index (2.6 vs. 2.47 L/min/m²; p=0.855) for both groups were almost identical due to the increase in heart rate in the hip fracture group. Regarding other parameters including ejection fraction, fractional shortening, E/E′, and inferior vena cava diameter, there were no significant differences between the two groups. Our noninvasive TTE investigations suggested that hip fracture patients were volume-depleted, and the hypovolemic status activated the sympathetic nervous system, compensating for their cardiac output. Anesthesiologists must focus on the TTE-assessed parameters reflecting the volume status along with the cardiac function.