Agreement Between Ventricular-Arterial Coupling Measured by Carotid Ultrasound and Transesophageal Echocardiography in Cardiac Surgery Patients:A Proof-of-Concept Study

Abstract Objective Ventricular-arterial coupling (VAC), defined as the ratio of arterial elastance (Ea) to end-systolic left ventricular elastance (Ees), provides valuable insights for optimizing perioperative hemodynamic management. While transthoracic and transesophageal echocardiography (TEE) are used to estimate Ees, both modalities require substantial operator expertise and TTE may be limited by suboptimal imaging conditions, especially in the perioperative setting. Therefore, we propose using carotid ultrasound as a non-invasive and more accessible alternative to estimate VAC. Given its close anatomical and physiological relationship with the proximal aorta, the carotid artery reflects central arterial hemodynamics and may serve as a promising surrogate for VAC. This study aims to evaluate the agreement between carotid ultrasound and TEE in measuring VAC in patients undergoing cardiac surgery. Design Prospective observational pilot study. Settings Operation room. Participants Twelve adult patients undergoing elective coronary artery bypass grafting surgery. Interventions Ultrasound measurements were obtained both pre- and postoperatively using carotid ultrasound and TEE, and the interchangeability between Ea, Ees, and VAC was evaluated with correlation and Bland-Altman analyses. Ea was calculated using using the SBP and SV, while Ees was estimated using Chen's single-beat method. Measurements & Main Results Strong correlations were observed between carotid ultrasound and TEE measurements for Ea (r=0.87, 95% CI [0.73:0.95]), Ees (r=0.82, 95% CI [0.63:0.92]), and VAC (r=0.79, 95% CI [0.56:0.90]). The estimation of VAC using carotid ultrasound demonstrated clinically acceptable accuracy and precision, with a bias of -0.01 (95% CI [-0.07:0.05]) and limits of agreement (LOA) of ±0.30 (range: -0.18 to 0.39). Conclusion Carotid ultrasound derived VAC demonstrated good correlation with VAC measured using TEE in this pilot study. These preliminary results suggest that carotid ultrasound may be useful for investigating VAC at the bedside, but further studies with larger sample sizes are needed to validate these findings.