Background: The so-called Low Cardiac Output Syndrome (LCOS) is one of the most common complications in pediatric patients with congenital heart disease undergoing corrective surgery. LCOS requires high concentrations of inotropes to support cardiac contractility and improve cardiac output, allowing for better systemic perfusion. To date, serum lactate concentrations and central venous oxygen saturation (ScVO₂) are the most commonly used perfusion markers, but they are not completely reliable in identifying a state of global tissue hypoxia. The study aims to evaluate whether the venoarterial carbon dioxide difference/arterial-venous oxygen difference ratio [P(v-a)CO₂/C(a-v)O₂] can be a good index to predict the development of LCOS in the aforementioned patients, so as to treat it promptly. Methods: This study followed a population of 98 children undergoing corrective cardiac surgery from June 2018 to October 2020 at the Department of Cardiac Surgery of University Hospital Integrated Trust and their subsequent admission at the Postoperative Cardiothoracic Surgery Intensive Care Unit. During the study, central arterial and venous blood gas analyses were carried out before and after cardiopulmonary bypass (CPB) (pre-CPB and post-CPB), at admission to the intensive care unit, before and after extubation, and at any time of instability or modification of the patient’s clinical and therapeutic conditions. Results: The data analysis shows that 46.9% of the children developed LCOS (in line with the current literature) but that there is no statistically significant association between the P(v-a)CO₂/C(a-v)O₂ ratio and LCOS onset. Despite the limits of statistical significance, however, a 31% increase in the ratio emerged from the pre-CPB phase to the post-CPB phase when LCOS is present. Conclusions: This study confirms a statistically significant association between the most used markers in adult patients (serum lactate concentration, ScVO₂, and oxygen extraction ratio—ERO₂) measured in the pre-CPB phase and the incidence of LCOS onset, especially in patients with hemodynamic instability before surgery.

Objectives: This study's primary purpose was to demonstrate the correlation of preoperative right ventricular free‐wall longitudinal strain (RVFWLS) and pre‐/postsurgical variation in strain (delta strain) with the clinical and echocardiographic diagnosis of right ventricular dysfunction. Its secondary purpose was to determine the correlation of RVFWLS and delta strain with length of stay (LOS) in the intensive care unit (ICU), ventilation days, trend of natriuretic peptide test. (NT‐proBNP) and lactate in the first 48 h, incidence of acute renal failure, and 28‐day mortality.Design: Prospective observational study.Setting: Cardio‐thoracic and Vascular Anaesthesia Department and ICU of the University Hospital Integrated Trust of Verona.Participants: Patients scheduled for mitral surgery.Interventions: None.Measurements and Main Results: All clinical and transoesophageal echocardiographic (TEE) parameters were collected at baseline, before surgery (T1) and at admission in the ICU postsurgery (T2). During the postoperative period, the clinical and echocardiographic diagnoses of right, left, or biventricular dysfunction were evaluated. TEE parameters were evaluated by a cardiologist offline. The patients were divided into two subgroups according to the development of any type of ventricular dysfunction. No statistically significant differences emerged between the two groups. According to a logistic regression model, a T1‐RVFWLS value of −15% appeared to predict biventricular dysfunction (sensitivity: 100%; specificity: 91.3%). No correlation between T1‐ or T2‐RVFWLS and creatinine, hours of ventilation or ICU LOS was found.Conclusions: Our study introduces a new parameter that could be used in perioperative evaluations to identify patients at risk of postoperative biventricular dysfunction.

BACKGROUNDː The so-called Low Cardiac Output Syndrome (LCOS) is one of the most common complications in pediatric patients with congenital heart disease undergoing corrective surgery. LCOS requires high concentrations of inotropes to support cardiac contractility and improve cardiac output, allowing for a better systemic perfusion. To date, serum lactate concentrations and central venous oxygen saturation (ScVO2) are the most commonly used perfusion markers, but they are not completely reliable to identify a state of global tissue hypoxia. The study aims to evaluate whether the venoarterial carbon dioxide difference/arterial-venous oxygen difference ratio [P(v-a)CO2/C(a-v)O2] can be a good index to predict the development of LCOS in the aforemen-tioned patients, so as to treat it promptly. METHODSː This study followed a population of 98 children undergoing corrective cardiac surgery from June 2018 to October 2020 at the Department of Cardiac Surgery of University Hospital Inte-grated Trust and their subsequent admission at the Postoperative Cardiothoracic Surgery Intensive Care Unit. During the study, central arterial and venous blood gas analysis were carried out before and after cardiopulmonary bypass (CPB) (pre-CPB and post-CPB), at admission to intensive care unit, before and after extubation and at any time of instability or modification of the patient’s clinical and therapeutic conditions. RESULTSː The data analysis shows that 46.9% of the children developed a LCOS (in line with the current literature) but that there is no statistically significant association between the P(v-a)CO2/C(a-v)O2 ratio and LCOS onset. Despite the limits of statistical significance, however, a 31% increase in the ratio emerged from the pre-CPB phase to the post-CPB phase when LCOS is present. CONCLUSIONSː This study confirms a statistically significant association between the most used markers in adult patients (serum lactate concentration, ScVO2 and oxygen extraction ratio-ERO2) measured in the pre-CPB phase and the incidence of LCOS onset, especially in patients with he-modynamic instability before surgery.

Ventricular–arterial coupling (VAC) describes the dynamic interaction between left ventricular (LV) systolic elastance and the time-varying elastance/impedance of the arterial tree, a relationship that governs the instantaneous generation of aortic flow and ultimately cardiac output. VAC, typically expressed as the ratio of effective arterial elastance (Ea) to LV end-systolic elastance (Ees), has provided valuable mechanistic and prognostic insights, but is limited by its lumped, largely steady-state nature and by the need for pressure–volume modeling or complex surrogate formulas. Contemporary time-domain and wave-intensity approaches have underscored that the shape of proximal aortic pressure–flow waveforms encodes rich beat-by-beat information about ventricular–arterial interaction and energy transfer. Doppler echocardiography of the ascending aorta provides a readily available, high-temporal resolution measure of proximal aortic flow that is already used to quantify stroke volume, cardiac output and valvular lesions. We propose that proximal aortic flow, as recorded by Doppler echocardiography, may serve as a clinically practical proxy for beat-by-beat VAC, reflecting the instantaneous matching of ventricular and aortic elastances, which regulates the ejected flow towards peripheral tissues according to metabolic needs.