単心室症

For more than a century, the pressure-volume loop has offered a simple and elegant way to show how the heart pumps blood. In one picture, it summarizes how the heart fills, contracts, and ejects blood. However, this simplicity has a limitation: the loop treats the heart as if it were a single, uniform chamber. Therefore, it cannot reveal many important biological and mechanical processes that influence how the heart truly works. This helps explain why some patients develop symptoms or early signs of heart problems even when their pressure-volume measurements look completely normal. In this Perspective, we describe the pressure-volume relationship not as a stand-alone measure but as an emergent phenotype - the visible "end result" of many processes happening at different levels. Beneath the loop are the molecular and cellular mechanisms that control how heart muscle contracts and relaxes. Beyond the loop are differences in how various regions of the heart function, the organised patterns of blood flow inside the ventricle, and the continuous interaction between the heart and the rest of the circulatory system. We discuss how advanced imaging, flow visualization techniques, and computational modelling can add depth to pressure-volume analysis, revealing mechanisms that global, chamber-level measurements cannot show. Seen this way, the familiar loop becomes a window into an individual patient's underlying biology, helping clinicians diagnose problems earlier and more accurately. This approach may help reveal the true mechanisms behind seemingly normal pressure-volume loops and support more precise, targeted treatments.

BACKGROUND: The incidence and risk factors of cardiac surgery-associated acute kidney injury (CS-AKI) are variable. We describe the incidence of severe postoperative CS-AKI (i.e., stage 2 or 3 AKI) and operative mortality in total neonates and in neonates with single ventricle (SV) physiology at a high-volume heart center. Additionally, we determine risk factors associated with severe CS-AKI and operative mortality. METHODS: A single-center, retrospective cohort study of neonates who underwent STAT (The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery) category 3, 4, and 5 surgeries between June 2015 and June 2022 was conducted. AKI was defined using the neonatal Kidney Disease Improved Global Outcome criteria. The cohort was compared based on SV physiology vs. biventricular physiology, development of stage 2 or 3 AKI vs. no AKI or stage 1 AKI, and operative mortality. Associations of risk factors were determined using univariate and multivariate analyses. RESULTS: Our study included 501 neonates, 223 (45%) of which had SV physiology. About 50% developed stage 2 or 3 AKI in both neonatal and SV cohorts. The operative mortality rate was 8% for total neonates and 14% for SV neonates. Following multivariate analyses, longer cardiopulmonary bypass time and delayed sternal closure were associated with severe AKI stages and operative morality. A lower preoperative creatinine was independently associated with severe postoperative AKI. CONCLUSIONS: There is a high prevalence of CS-AKI and operative mortality in both of our neonatal cohorts, with multiple risk factors associated with both outcomes. Future prospective, multi-center, randomized studies and development of an AKI prediction tool are necessary to further investigate these findings.

BACKGROUND: Prone positioning is an essential component of early rehabilitation and motor development in infants following cardiac surgery involving median sternotomy; however, restrictions remain variable due to concerns regarding sternal healing and safety. Due to a lack of guiding evidence, many institutions implement a time-based restriction to prone positioning. METHODS: A retrospective cohort study was conducted of infants with single-ventricle physiology undergoing cardiac surgery via median sternotomy at a single paediatric centre between 2022 and 2025. Data collected included time to physical therapy evaluation, time to initiation of prone positioning, clinical factors influencing positioning, and sternal healing outcomes after discharge. Descriptive statistics were used to summarise timing and outcomes. RESULTS: A total of 37 patients were included with 46 surgical encounters. The median age at first surgery was 65 days (interquartile range: 6-204). Physical therapy evaluation occurred at a median of 9 days post-operatively (interquartile range: 7-15; range: 3-29), and prone positioning was initiated at a median of 15 days (interquartile range: 10-22; range: 4-115). Timing differed by surgical stage, with earlier initiation following Glenn compared to Norwood procedures. Delays in prone positioning were associated with medical instability, delayed sternal closure, and the presence of invasive lines and devices. No cases of sternal dehiscence, infection, or adverse healing outcomes were identified at outpatient follow-ups. CONCLUSIONS: Prone positioning following infant cardiac surgery demonstrates variability in timing but appears safe when guided by clinical stability and patient-specific factors. These findings support a shift from time-based restrictions to individualised, criteria-driven approaches.

BACKGROUND: Reentrant atrial tachycardias (ATs) are frequent after atrial switch for dextro-transposition of the great arteries and are associated with adverse prognosis. Catheter ablation is first-line therapy, yet long-term outcomes and predictors of recurrence remain poorly defined. Our aim was to characterize induced AT circuits, describe acute and long-term catheter ablation outcomes, and identify recurrence predictors in dextro-transposition of the great arteries. METHODS: Single-center ambispective cohort of consecutive adults with dextro-transposition of the great arteries undergoing a first AT ablation (2003-2025). Arrhythmias were mechanically induced with decremental pacing or extra stimuli. Acute success was defined as elimination of all clinical and reproducibly inducible tachycardias (cycle length >200 ms), with bidirectional cavotricuspid isthmus block when applicable. Recurrence was defined as any documented AT >30 seconds. RESULTS: Thirty-three patients underwent 46 procedures. During the index procedure, 66 ATs were induced; 51 (83%) were characterized: 32 (63%) were cavotricuspid isthmus-dependent and 11 (22%) incisional. Cavotricuspid isthmus block was achieved in 84%; acute noninducibility in 73%. Median follow-up was 7.0 years (interquartile range, 2.5-10.4). Overall, 15 patients (45.5%) recurred; 1-year freedom was 75%. Recurrence was strongly associated with failed or uncertain acute efficacy, severely impaired systemic right ventricular fractional shortening ≤22%, prolonged PR interval (220 ms), and greater number of inducible ATs (all P<0.05). In multivariable modelling, these 4 variables yielded an optimism-corrected C-index of 0.85. Eleven (33%) underwent redo ablation; 8 achieved acute noninducibility, and only 3 recurred thereafter. CONCLUSIONS: In dextro-transposition of the great arteries postatrial switch, cavotricuspid isthmus-dependent flutter is most common, but scar-related circuits are frequent. Catheter ablation is safe and acutely effective, but long-term recurrence remains substantial. Failed acute efficacy, severely impaired systemic right ventricle contractility, prolonged PR interval, and multiple inducible ATs identify patients at highest risk and may guide follow-up and referral for early repeat ablation.

BACKGROUND: The Fontan procedure constitutes the definitive surgical strategy for complex congenital heart disease, establishing a circulation in which systemic venous blood is directed to the pulmonary arteries through a staged reconstruction that separates systemic and pulmonary venous return in the absence of a subpulmonary ventricle. This uniquely altered haemodynamic state exerts deleterious effects on endothelial function, thereby promoting progressive end-organ dysfunction and contributing substantially to the long-term morbidity observed in patients with Fontan circulation. ΜETHODS/RESULTS: Over recent decades, clinical research has employed a range of functional methods to assess macro- and microvascular function, as well as arterial stiffness. This review summarizes the available functional non-invasive techniques for evaluating vascular function in the Fontan circulation and discusses the existing evidence linking these vascular parameters to cardiac dysfunction, associated comorbidities, and clinical outcomes in this population. CONCLUSIONS: Functional non-invasive vascular assessment may provide valuable information for monitoring disease progression and risk stratification in Fontan circulation; however, further longitudinal studies are required to clarify its prognostic significance and potential clinical utility.