Introduction/Background: Current knowledge of a Stage 1 shunted single ventricle (SSV) physiology is predominantly based on clinical data. Development of a reliable and reproducible SSV animal model can facilitate pre-clinical research on strategies to improve outcomes. Research Questions/ Hypothesis: We hypothesize that a functional SSV animal model can be created by percutaneously creating a large atrial communication, placing a systemic to pulmonary artery shunt and excluding the right ventricle (RV) from the circulation. Goals/Aims: We aimed to create a neonatal porcine SSV model without using cardiopulmonary bypass. Methods/Approach: Neonatal pigs (n=8; weight 6.1±2.6 kgs) were used. A median sternotomy was performed. A 6-mm ring enforced PTFE graft was anastomosed end-side to the main pulmonary artery (MPA), end-end to the innominate artery and occluded with a vascular clamp. Under epicardial echocardiography guidance, the atrial septum was percutaneously perforated using electrocautery. (Figure 1A). Electrocautery was applied using a coaxial system of 4 Fr JR 3 catheter and a 0.014-inch coronary wire with its denuded tip at the atrial septum. Balloon atrial septostomy was performed using B. Braun Z-5 13.5 mm and/or the Edwards Miller septostomy balloon. To prevent RV distension, a per-ventricular Tricuspid valve (TV) avulsion was done using a Rumel tourniquet guide as a snare placed through a 7 Fr per-ventricular sheath (Figure 1B) . The systemic to pulmonary artery shunt (SPS) was unclamped, and antegrade pulmonary blood (APF) was interrupted by the occlusion of the MPA. Inotropic support was initiated. Donor pig blood was transfused for volume replacement. Hemodynamic and laboratory data were collected. The circulation was maintained for a minimum duration of 1 hour. Results/Data: The SSV was successfully created in 6 out of 8 animals. The SSV circulation had a mean arterial pressure of 37.5±12 mmHg and a common atrial pressure of 12±6 mmHg. The mean aortic flow was 0.76±0.34 L/min, and the systemic to pulmonary artery shunt flow was 0.36±0.23 L/min. The mean Qp/Qs ratio was 1.27±1.14. The systemic saturation was 82±16%, and the mixed venous saturation was 58±17%. Conclusions: A porcine animal model of an SSV circulation can be created without using cardiopulmonary bypass by performing a percutaneous atrial septostomy, per ventricular TV avulsion, placing a SPS and interrupting APF. This model effectively replicates the stage 1 SSV physiology.

ObjectivesLeft ventricular assist devices are part of the foundations of mechanical circulatory support. As such devices evolve in technology, so does their implantation techniques, becoming less invasive. We developed a novel blood-guiding accessory for less invasive implantation, redirecting the blood intracardially into the ascending aorta through a transaortic outflow.MethodsTen healthy female swine (German Landrace, 104.4 ± 13.0 kg) underwent epicardial echocardiography before and after left ventricular assist device implantation. Cardiac geometry, aortic valve function, and outflow positioning were assessed before and after implantation.ResultsEpicardial echocardiography revealed sufficient biventricular unloading after device implantation. The end-diastolic and end-systolic left ventricular diameters decreased by 16% and 20%, respectively. Retrograde unloading was displayed by smaller diameters in left and right atria at 22% and 25%, respectively. At baseline, 1 animal presented mild aortic regurgitation, unchanged under mechanical support, whereas 1 developed mild de novo insufficiency. The outflow graft was either well centred within the aortic valve (n = 3) or between 2 cusps.ConclusionsA left ventricular assist device with the accessory allowed sufficient ventricular unloading, preserving biventricular function. Although the outflow graft was well centred within the aortic valve in only 30% of the cases, no relevant aortic regurgitation was found in the acute setting. Chronic testing in larger samples is required to analyse results in long term.

Hypertrophic obstructive cardiomyopathy (HOCM), a subset of hypertrophic cardiomyopathy (HCM), is characterized by dynamic left ventricular outflow tract (LVOT) obstruction, often caused by systolic anterior motion (SAM) of the mitral valve and septal hypertrophy. Accurate intraoperative assessment of septal morphology, SAM distance, and LVOT area (LVOTa) is critical for surgical planning during septal myectomy. While transesophageal echocardiography (TEE), particularly with three-dimensional (3D) imaging, is the standard modality for evaluating these parameters, it may be contraindicated or suboptimal in select cases. Real-time 3D epicardial echocardiography (EE) offers an alternative imaging approach that allows direct visualization of the heart intraoperatively without esophageal instrumentation. This study investigates the utility of 3D EE compared to 3D TEE for quantitative assessment of septal left ventricular wall thickness (LVWT), SAM distance, and LVOTa in HOCM patients undergoing myectomy. The primary aim is to assess whether 3D EE and TEE measurements correlate and can be used interchangeably. A secondary aim is to compare 2D and 3D measurements by both modalities. Perioperative data of 59 patients with HOCM were obtained by retrospective review in a tertiary care setting. 2D and 3D intraoperative transesophageal and EE studies were assessed performing multiple measurements relevant for myectomy. Demographic and clinical data were summarized with descriptive statistics, while the Altman-Bland method assessed the interchangeability of three-dimensional transesophageal and EE measurements. Inter- and intraobserver variabilities were evaluated using the Bland-Altman method and intraclass correlation coefficient. Off-line analysis of 3D data sets with Qlab Phillips was feasible in 79.7% of the patients. No significant differences were found between epicardial and transesophageal echocardiographic intraoperative measurements by 2D: septal LVWT (P=0.59), SAM distance (P=0.40) or LVOTa (P=0.22), or by 3D: septal LVWT (P=0.42), SAM distance (P=0.23) or LVOTa (P=0.38). Intraoperative EE demonstrates equal potential utility in guiding HOCM patients when TEE is not an option or is contraindicated. These findings underscore the clinical significance of EE as a reliable alternative for image guidance during myectomy in HOCM patients, contributing to improved surgical outcomes.

Acute loss of mitral annular dynamics predicts development of functional mitral regurgitation after myocardial infarction in a swine model.

The usefulness of color Doppler images using epicardial echocardiography for diagnosis of coronary artery ostial stenosis in an infant.

Abstract The left superior vena cava (LSVC) develops when the left common cardinal vein and the caudal part of the left superior cardinal vein fail to regress. We present a case where LSVC was associated with a bridging vein and coronary sinus ostial atresia. The dilated coronary sinus, which is the usual echocardiographic indicator of LSVC, is absent in this scenario. A 14 month old boy with tetralogy of Fallot underwent intracardiac repair; he was noticed to have a small LSVC; it was snared in order to proceed with surgery. During delivery of antegrade cardioplegia, there was resistance, the right atrium was opened immediately and coronary sinus ostium was found to be atretic. The snare around the LSVC was immediately released which enabled the delivery of further cardioplegia. The LSVC was then snared after cardioplegia delivery, and the intracardiac repair was done. The heart recovered in sinus rhythm, and the child was shifted with moderate inotropic support. Post-operative epicardial echocardiography confirmed retrograde flow in the LSVC from the coronary sinus to the innominate vein. LSVC with coronary sinus ostial atresia, although rare, should be recognised by the presence of retrograde flow in the LSVC. This could have significant implications for cardioplegia delivery and myocardial protection. Ligation or division of LSVC should not be done in the presence of retrograde flow in the vein with a small coronary sinus.

The Impella CP is a percutaneously inserted temporary left ventricular assist device used in clinical practice and in translational research into cardiogenic shock, perioperative cardiac surgery, acute cardiac failure and mechanical circulatory support. Fluoroscopic guidance is usually used for insertion of an Impella, thus limiting insertion to within catheterization laboratories. Transthoracic, transoesophageal and intracardiac echocardiography have been reported to guide Impella CP implantation with identified specific limitations stemming from the surgical, anatomical and equipment factors. We conducted translational prospective descriptive feasibility investigation as a part of two other hemodynamic Impella studies. It showed the successful application of epicardial echocardiographic scanning for implantation of Impella CP devices in ovine models, from which details of the technique and identified pitfalls are described with practical solutions for future investigators and clinicians. Many described findings are relevant to any other echocardiographic techniques when adequate imaging of the Impella and relevant anatomical structures is achievable.Graphical

Ischemic mitral regurgitation (IMR) imposes volume overload on the left ventricle (LV), accelerating adverse LV remodeling. In this study, we sought to investigate the impact of volume overload due to IMR on regional myocardial contractile mechanics. Ten Yorkshire swine were induced with myocardial infarction (MI) by occluding the left circumflex coronary artery (LCx). Cardiac MRI was performed at baseline (BL) and 2.5 months (2.5M) post-MI. IMR was quantified with epicardial echocardiography 3 months post-MI. The animals were then assigned to 2 groups: no/mild MR (nmMR, n = 4) and moderate/severe MR (msMR, n = 6). MRI images were analyzed to assess infarction size, end-diastolic and end-systolic volume (EDV and ESV, respectively), ejection fraction (EF), longitudinal strain (LS), circumferential strain (CS), and systolic dyssynchrony index (SDI). The myocardial region was divided into infarction, border, and remote zones based on the LCx-supplied region. There was no difference in the infarction size. Group-wise comparison of LS and CS between BL and 2.5M demonstrated that LS and CS in the infarction zone and the border zone decreased at 2.5M in both groups. However, LS and CS in the remote zone were elevated only in the msMR group (LS: -9.81 ± 3.96 vs. -12.58 ± 5.07, p < 0.01; CS; -12.78 ± 3.81 vs. -16.09 ± 3.33, p < 0.01) at 2.5M compared to BL. The SDI of CS was significantly elevated in the msMR group (0.1255 vs. 0.0974, p = 0.015) at 2.5M compared to BL. Elevated LS and CS in the remote zone were observed in moderate/severe MR and ventricular dyssynchrony. These elevated cardiac strains, coupled with ventricular dyssynchrony, may contribute to the progression of MR, thereby accelerating heart failure.

BackgroundSwine are frequently used as animal model for cardiovascular research, especially in terms of representativity of human anatomy and physiology. Reference values for the most common species used in research are important for planning and execution of animal testing. Transesophageal echocardiography is the gold standard for intraoperative imaging, but can be technically challenging in swine. Its predecessor, epicardial echocardiography (EE), is a simple and fast intraoperative imaging technique, which allows comprehensive and goal-directed assessment. However, there are few echocardiographic studies describing echocardiographic parameters in juvenile swine, none of them using EE. Therefore, in this study, we provide a comprehensive dataset on multiple geometric and functional echocardiographic parameters, as well as basic hemodynamic parameters in swine using EE.MethodsThe data collection was performed during animal testing in ten female swine (German Landrace, 104.4 ± 13.0 kg) before left ventricular assist device implantation. Hemodynamic data was recorded continuously, before and during EE. The herein described echocardiographic measurements were acquired according to a standardized protocol, encompassing apical, left ventricular short axis and long axis as well as epiaortic windows. In total, 50 echocardiographic parameters and 10 hemodynamic parameters were assessed.ResultsEpicardial echocardiography was successfully performed in all animals, with a median screening time of 14 min (interquartile range 11–18 min). Referring to left ventricular function, ejection fraction was 51.6 ± 5.9% and 51.2 ± 6.2% using the Teichholz and Simpson methods, respectively. Calculated ventricular mass was 301.1 ± 64.0 g, as the left ventricular end-systolic and end-diastolic diameters were 35.3 ± 2.5 mm and 48.2 ± 3.5 mm, respectively. The mean heart rate was 103 ± 28 bpm, mean arterial pressure was 101 ± 20 mmHg and mean flow at the common carotid artery was 627 ± 203 mL/min.ConclusionEpicardial echocardiography allows comprehensive assessment of most common echocardiographic parameters. Compared to humans, there are important differences in swine with respect to ventricular mass, size and wall thickness, especially in the right heart. Most hemodynamic parameters were comparable between swine and humans. This data supports study planning, animal and device selection, reinforcing the three R principles in animal research.Graphical

Perioperative echocardiography is of paramount importance during cardiac surgery. Nonetheless, in the experimental large-animal setting, it might be challenging obtaining optimal imaging when using conventional imaging acquisition techniques, such as transthoracic and transesophageal screenings. Open-chest surgery allows epicardial echocardiographic assessment with direct contact between probe and heart, thus providing superior quality. Standard protocols regarding the use of epicardial ultrasound in swine for research purposes are lacking. Epicardial echocardiography was performed in 10 female German Landrace pigs undergoing cardiac surgery. A structured and comprehensive protocol for epicardial echocardiography was elaborated including apical, ventricular long and short axis, as well as epiaortic planes. All experiments were approved by the local board for animal welfare and conducted in accordance with the German animal protection law (TierSchG) and the ARRIVE guidelines. Systematic protocols using epicardial echocardiography may serve as an additional tool to assess cardiac dimensions and function in experimental scenarios with swine models.

BackgroundAnatomic anomalies in the ascending aorta may impair the implantation and testing of cardiovascular devices in humans and animal models.Case presentationWe present the rare case of an intra-aortic band in a German Landrace pig. During terminal animal testing, the band hindered the implantation of a left ventricular assist device (LVAD) with transventricular outflow graft across the aortic valve. After lower partial sternotomy, epicardial echocardiography displayed an intraluminal echogenic structure at the sinotubular junction causing unspecific flow turbulences. Under cardiopulmonary bypass, coring of the left ventricular apex was performed. Due to strong resistance in the proximal aorta, accurate positioning of the transventricular LVAD outflow graft was impossible. After euthanasia, necropsy revealed a fibrous band located at the sinotubular junction, dividing the lumen of the ascending aorta.ConclusionsThe occurrence of an intra-aortic band represents an extremely rare case of a most likely congenital anomaly. Awareness of such anomalies is important for planning and performing animal testing. Perioperative echocardiography may help to either remove such anomalies or allow discontinuing the procedure prior to device implantation.

The ValveClasp system is a novel transcatheter edge-to-edge repair (TEER) device with an arm-width-expandable clip that allows treatment of patients with only one clip more frequently. This study aimed to evaluate the feasibility and safety of a novel TEER device in porcine models and patients. Fourteen young adult pigs were enrolled. A clip with an expanded arm was implanted under epicardial echocardiography and fluoroscopy guidance. Five patients with at least moderate-to-severe mitral regurgitation underwent TEER using the ValveClasp system to test the safety and effectiveness of the device. The device success rate was 100% (14/14) in the animal experiments, and all clips were deployed at the A2P2 segments, forming a double-orifice mitral valve. Gross observations on day 180 showed a wide and continuous tissue bridge between the leaflets. The acute procedural success rate was 100% (5/5). Only one clip was required in all patients, and all achieved effective postoperative endpoints (grade ≤2+). During 30-day follow-up, no adverse events occurred. All patients'vena Contracta width (from 8.04 0.71 mmto 3.84 ± 1.18 mm, p = 0.012), mitral regurgitation area (from 12.75 ± 3.13 cm2 to 3.50 ± 1.66 cm2 , p = 0.008), and left ventricular end diastolic diameter (from 52.00 ± 2.92 mm to 46.00 ± 3.08 mm, p = 0.040) were considerably decreased, without obvious mitral stenosis. The novel arm-width-expandable ValveClasp device is safe for TEER for treating severe mitral regurgitation.

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Septal annular dilation in chronic ovine functional tricuspid regurgitation

The pathophysiology of severe functional tricuspid regurgitation (FTR) associated with right ventricular dysfunction is poorly understood, leading to suboptimal clinical results. We set out to establish a chronic ovine model of FTR and right heart failure to investigate the mechanisms of FTR. Twenty adult male sheep (6-12 months old, 62 ± 7 kg) underwent a left thoracotomy and baseline echocardiography. A pulmonary artery band (PAB) was placed and cinched around the main pulmonary artery (PA) to at least double the systolic pulmonary artery pressure (SPAP), inducing right ventricular (RV) pressure overload and signs of RV dilatation. PAB acutely increased the SPAP from 21 ± 2 mmHg to 62 ± 2 mmHg. The animals were followed for 8 weeks, symptoms of heart failure were treated with diuretics, and surveillance echocardiography was used to assess for pleural and abdominal fluid collection. Three animals died during the follow-up period due to stroke, hemorrhage, and acute heart failure. After 2 months, a median sternotomy and epicardial echocardiography were performed. Of the surviving 17 animals, 3 developed mild tricuspid regurgitation, 3 developed moderate tricuspid regurgitation, and 11 developed severe tricuspid regurgitation. Eight weeks of pulmonary artery banding resulted in a stable chronic ovine model of right ventricular dysfunction and significant FTR. This large animal platform can be used to further investigate the structural and molecular basis of RV failure and functional tricuspid regurgitation.

Indispensable Role of Transesophageal Echocardiography in Double-Chamber Right Ventricle Repair Surgery

Background & aims Intracardiac shunts are abnormal channels of blood circulation within the heart that develop eitheras an additional blood flow pathway or as a replacement for the normal channels of blood circulation. They are the commonest types of congenital heart defects. Various methods are available in the present times to identify, localize or quantify left-to-right intracardiac shunts. Methods may vary in sensitivity, indicators, or types of equipment available. One such method used in almost all cardiac centers for a long time has been oximetry runto detect step-up differences in oxygen saturation values. In the oximetry runthe main approach to detect and estimate the left-to-right (L-->R) shuntsrequires the oxygen concentration expressed as a proportion of saturation to be evaluated in blood samples which are obtained from the right atrium (RA) and pulmonary artery (PA), respectively. A left-to-right shunt can be considered if there is a significant increase (step-up) in bloodsaturation. A significant step-up is defined as a substantial rise in blood oxygen content or saturation that is higher than normal values. Methods Using a prospective observational design, this article investigates the application of the step-up method in detecting intracardiac shunts. The study was conducted between 2021 and 2022 on 35 pediatric cardiac patients (males/females, 24/11) diagnosed with post-tricuspid shunts. The pulmonary artery and right atrium were sampled before and after cardiopulmonary bypass surgery and analyzed using a blood gas test. As a result, nearly 91% of the patients had a saturation below 8%. However, the difference between PA oxygen saturation (SO2) & RASO2 before and after surgery was significant. As a result, the difference in O2 saturation helped detect the residual ventricular septal defect (VSD) after the surgery. Results There were no deaths or complications in this study. There were no re-interventions for post-tricuspid shunt surgery, though one patient had a step-up of >15% and residual VSD status was moderate to large on two-dimensional (2D) echocardiography. Conclusion A combination of physical findings, chest radiography, electrocardiogram (ECG), and echocardiography is routinely done for all these patients undergoing pediatric cardiac surgery. Echocardiography can detect the occurrence of shunt but does not calculate the shunt ratio. Transesophageal or epicardial echocardiography is the standard of care but has its limitations like perception difference between the operating surgeon and the person performing echocardiography. In this study, we have added an oximetry analysis of blood-gas samples before and after surgery and compared it to 2D echocardiography to test the validation of oximetry in isolation and comparison to 2D echocardiography.

In the typical left-to-right patent ductus arteriosus (PDA), the shunt flows from the ductus arteriosus towards the pulmonary valve. Although hemodynamic changes have been carefully studied in dogs with PDA, there is very little information on the outcomes of the pulmonary valve after surgical correction of PDA. This study aimed to visualize the pulmonary valve by transthoracic echocardiography in dogs with PDA before and after surgical ligation. Prior to surgery, the movement of the anterior semilunar cusp of the pulmonary valve was obstructed by the shunted blood flow during systole in all nine dogs with PDA in this study. M-mode echocardiography revealed a continuous trajectory of the cusp, because the cusp was pushed towards the right ventricle during the whole cardiac cycle by the shunted flow. Epicardial echocardiography performed in one dog during surgical ligation of the ductus arteriosus revealed that the movement of the anterior semilunar cusp normalized immediately after ligation. B- and M-mode echocardiography may be used to support the diagnosis of PDA through observation of the pulmonary valve when color Doppler echography is not available. The findings in this study may be of importance in distinguishing PDA from PDA-mimicking diseases worth considering before the treatment process (e.g. aorticopulmonary fistulas or aberrant arteriovenous shunts). Supplementary InformationThe online version contains supplementary material available at 10.1007/s11259-022-10003-y.

Left ventricular distension is a major concern with postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO) supporting a critical heart failure after cardiac surgery. This porcine study evaluates the effects of left ventricular venting on cardiac function during ECMO-supported circulation and after weaning from ECMO. Twenty anaesthetised open-chest pigs were put on cardiopulmonary bypass with aortic cross-clamping and suboptimal cardioplegic arrest for 40min. After declamping and defibrillation, the animals were supported by VA-ECMO for 180min either with or without additional left ventricular venting. Continuous haemodynamic evaluations were performed at baseline and at cardiac arrest, during VA-ECMO and for 120min after weaning from circulatory support. Left ventricular perfusion and function were evaluated with microspheres, pressure-volume loops and epicardial echocardiography at baseline and after 1 and 2h with unsupported circulation. In vented animals both mean aortic and left ventricular peak systolic pressure increased at the end of the ECMO-supported period compared to those not vented and remained increased also after weaning. Both at 60 min and 120min after weaning from circulatory support, left ventricular stroke work and pressure-volume area were increased in vented compared to not vented animals. At 120min left ventricular stroke volume was increased in vented compared to not vented animals, myocardial perfusion did not differ. The left ventricular mechanical efficiency, defined as the ratio between pressure volume area and myocardial perfusion, was increased (53.2 ± 5 vs 36.2 ± 2.1J/mL/g, p = 0.011) in vented- compared to not vented hearts. This experimental study demonstrate that left ventricular venting during post-cardiotomy veno-arterial ECMO for 3h attenuates deterioration of left ventricular function and haemodynamics early after weaning from circulatory support.

OBJECTIVESReductive ring annuloplasty of the tricuspid annulus represents the contemporary surgical approach to functional tricuspid regurgitation (FTR). We set out to investigate the influence of moderate reductive tricuspid ring annuloplasty on tricuspid regurgitation and right ventricular (RV) size, geometry and strain in an ovine model of chronic FTR.METHODSEight healthy Dorsett male sheep (62.8 + 2kg) underwent a left thoracotomy for placement and tightening of pulmonary artery band to at least double proximal pulmonary artery blood pressure. After 8 weeks of recovery, animals underwent sternotomy, epicardial echocardiography and sonomicrometry crystal implantation. Six crystals were placed around tricuspid annulus and 13 on RV free wall epicardium along 3 parallels defining 3 wall regions (basal, mid and lower) and 1 on the RV apex. All animals underwent beating heart implantation of 26 mm MC3 annuloplasty ring during a second cardiopulmonary bypass run after baseline data acquisition. Simultaneous haemodynamic, sonomicrometry and echocardiography data were acquired at Baseline and after reductive tricuspid ring annuloplasty.RESULTSImplantation of reductive ring annuloplasty resulted in 47 ± 7% annular area reduction (996 ± 152 mm vs 516 ± 52 mm2, P = 0.0002) and significantly decreased RV end-diastolic volume (185 ± 27 vs 165 ± 30 ml, P = 0.02). Tricuspid ring annuloplasty effectively reduced FTR grade (3.75 ± 0.6 vs 0.3 ± 0.5, P = 0.00004) and had little influence on RV function, cross-sectional area, radius of curvature or free wall regional strains.CONCLUSIONSIn adult sheep with 8 weeks of pulmonary artery banding and FTR, tricuspid annulus reduction of 47% with prosthetic ring annuloplasty effectively abolished FTR while maintaining regional RV function and strain patterns.