Ultrasound beamforming plays a crucial role in the formation of an ultrasound image. The conventional delay-and-sum (DAS) method is efficient but susceptible to acoustic clutter which obscures imaging. While many clutter reduction techniques have emerged, recent efforts increasingly use deep neural network (DNN) beamformers trained on simulated data, which offers convenient access to ground truth. However, the domain gap between simulated training data and in vivo test data undermines model performance. Recent domain-adaptive work proposed to bridge the gap with a CycleGAN style-transfer map, but the limitation of the map and the source of domain mismatch remains poorly understood. This work seeks to identify the contribution of reverberation and phase aberration to the domain mismatch by selectively introducing them in simulation. We used KL divergence and Wasserstein-2 distance to quantify domain shift and validated their use with the downstream beamformer performance. Using the Wasserstein-2 distance between simulation data with no reverberation and phase aberration and in vivo data as reference, we showed that including aberration and reverberation in simulation reduced the domain gap by 7.4% and 45%, respectively. The domain gap was reduced by 53% when both sources of image degradation were included in simulation, and reduced by 64% with the use of CycleGAN maps. We further demonstrated that CycleGAN efficacy is dependent on source distribution and revealed that best beamformer results were achieved when reverberation and phase aberration were both present in simulation.

Identifying and treating pediatric arrhythmias is essential for pediatric anesthesiologists. Pediatric patients can present with narrow or wide complex tachycardias, though the former is more common. Patients with inherited channelopathies or cardiomyopathies are at increased risk. Since most pediatric patients present for anesthesia without a baseline electrocardiogram, the first identification of an arrhythmia may occur under general anesthesia. Supraventricular tachycardia, the most common pediatric tachyarrhythmia, represents a broad category of predominately narrow complex tachycardias. Stimulating events including intubation, vascular guidewire manipulation, and surgical stimulation can trigger episodes. Valsalva maneuvers are unreliable as treatment, making adenosine or other intravenous antiarrhythmics the preferred acute therapy. Reentrant tachycardias are the most common supraventricular tachycardia in pediatric patients, including atrioventricular reciprocating tachycardia (due to a distinct accessory pathway) and atrioventricular nodal reentrant tachycardia (due to an accessory pathway within the atrioventricular node). Patients with ventricular preexcitation, often referred to as Wolff-Parkinson-White syndrome, have a wide QRS with short PR interval, indicating antegrade conduction through the accessory pathway. These patients are at risk for sudden death if atrial fibrillation degenerates into ventricular fibrillation over a high-risk accessory pathway. Automatic tachycardias, such as atrial tachycardia and junctional ectopic tachycardia, are causes of supraventricular tachycardia in pediatric patients, the latter most typically noted after cardiac surgery. Patients with inherited arrhythmia syndromes, such as congenital long QT syndrome, are at risk of developing ventricular arrhythmias such as polymorphic ventricular tachycardia (Torsades de Pointes) which can be exacerbated by QT prolonging medications. Patients with catecholaminergic polymorphic ventricular tachycardia are at particular risk for developing bidirectional ventricular tachycardia or ventricular fibrillation during exogenous or endogenous catecholamine surges. Non-selective beta blockers are first line for most forms of long QT syndrome as well as catecholaminergic polymorphic ventricular tachycardia. Anesthesiologists should review the impact of medications on the QT interval and transmural dispersion of repolarization, to limit increasing the risk of Torsades de Pointes in patients with long QT syndrome. This review explores the key anesthetic considerations for these arrhythmias.

Abstract Background Enhancing venous return during cardiopulmonary resuscitation (CPR) can lead to better hemodynamics and improved outcome after cardiac arrest (CA). Peripheral Intravenous Analysis (PIVA) provides feedback on venous flow changes and may indicate an increase in venous return and cardiac output during CPR. We hypothesize PIVA can serve as an early indicator of increased venous return, preceding end-tidal CO2 (etCO2) increase, before the return of spontaneous circulation (ROSC) in a rat model of CA and CPR. Results Eight male Wistar rats were intubated and ventilated, and etCO2 was measured. Vessels were cannulated in the tail vein, femoral vein, femoral artery, and central venous and connected to pressure transducers. Ventilation was discontinued to achieve asphyxial CA. After 8 min, CPR began with ventilation, epinephrine, and automated chest compressions 200 times per minute until mean arterial pressure increased to 120 mmHg. Waveforms were recorded and analyzed. PIVA was calculated using a Fourier transformation of venous waveforms. Data are mean ± SE. Maximum PIVA values occurred in the tail vein 34.7 ± 2.9 s before ROSC, with subsequent PIVA peaks in femoral vein and centrally at 30.9 ± 5.4 and 25.1 ± 5.0 s, respectively. All PIVA peaks preceded etCO2 increase (21.5 ± 3.2 s before ROSC). Conclusion PIVA consistently detected venous pressure changes prior to changes in etCO2. This suggests that PIVA has the potential to serve as an important indicator of venous return and cardiac output during CPR, and also as a predictor of ROSC.

We previously showed that domain adaptive deep neural networks (DNNs) can outperform delay-and-sum (DAS) beamforming in the context of abdominal imaging. We hypothesize the ability of our domain adaptive DNN framework to be applied to transthoracic echocardiography (TTE). We also propose architectural improvements, such as leveraging an encoder-decoder structure and skip connections, to further improve ultrasound image quality for echocardiography tasks such as the detection of thrombi in the left atrial appendage (LAA). DNN training data utilized simulated and in vivo cardiac data. Simulated anechoic and hypoechoic cysts with various amounts of clutter were generated through Field II and in vivo data was collected by scanning patients at Vanderbilt University Medical Center. Fundamental frequency TTE data from five separate cases were processed with DAS, ADMIRE, the baseline model, and multiple models with modified architectures. We found that even when varying the amount of training data, the DNNs consistently achieved higher generalized contrast-to-noise (gCNR) and contrast ratio (CR) but lower contrast-to-noise ratio when compared to DAS. The best-performing beamformer was one DNN with our architectural improvements, achieving higher average gCNR and CR values of .907 and 48.30 dB compared to the baseline DNN values of .788 and 39.45 dB, and DAS values of .717 and 14.08 dB. Our results demonstrate that our domain adaptive DNN can effectively be applied in the context of transthoracic cardiology, and an encoder-decoder architecture with skip connections can result in even more improvements. Further advancements may improve image quality even more.

Deep neural network (DNN) beamformers have gained traction in ultrasound because of their ability to approximate any non-linear function. In clutter suppression, DNN beamformers can be trained using paired synthetic data by minimizing a loss computed between the prediction and ground truth. In this work, we showed that minimizing a conventional Smooth-L-1 loss does not correlate to improving the generalized contrast-to-noise (gCNR) ratio of the prediction. Instead, we propose to directly incorporate gCNR as a regularizer to the training loss and showed some improvement in synthetic data. Finally, we integrated gCNR regularization into an existing domain adaptation approach and achieved a gCNR gain of 0.0322 +/- 0.0336 over delay-and-sum.

The Medical imaging field has benefited from the application of deep networks. Early applications of deep network focused on image interpretation for the purposes of diagnosis (i.e. classification), and more recent work focuses on the use of deep networks for the image formation task (i.e. estimation). Here, we consider ultrasound image formation, and we discuss an approach to overcome the unlabeled data problem.

Anesthetists and anesthesiologists are frequently in the unique position of administering high-volume resuscitation in the setting of hemorrhage, hypovolemia, or vasodilatory shock. The ability to rapidly infuse intravenous (IV) fluid solutions differs vastly for different types and sizes of IV access. In patients that may require rapid large volume resuscitation, it is critical to understand the capacity of existing IV devices. Selecting the most appropriate IV access for patients can be paramount in preventing hypotension, end organ dysfunction, and even death. This article objectively reviews and compares the flow rates of commonly used central and peripheral intravenous devices to demonstrate the influence of catheter length and radius.

BACKGROUND: Early detection and quantification of perioperative hemorrhage remains challenging. Peripheral intravenous waveform analysis (PIVA) is a novel method that uses a standard intravenous catheter to detect interval hemorrhage. We hypothesize that subclinical blood loss of 2% of the estimated blood volume (EBV) in a rat model of hemorrhage is associated with significant changes in PIVA. Secondarily, we will compare PIVA association with volume loss to other static, invasive, and dynamic markers. METHODS: Eleven male Sprague Dawley rats were anesthetized and mechanically ventilated. A total of 20% of the EBV was removed over ten 5 minute-intervals. The peripheral intravenous pressure waveform was continuously transduced via a 22-G angiocatheter in the saphenous vein and analyzed using MATLAB. Mean arterial pressure (MAP) and central venous pressure (CVP) were continuously monitored. Cardiac output (CO), right ventricular diameter (RVd), and left ventricular end-diastolic area (LVEDA) were evaluated via transthoracic echocardiogram using the short axis left ventricular view. Dynamic markers such as pulse pressure variation (PPV) were calculated from the arterial waveform. The primary outcome was change in the first fundamental frequency (F1) of the venous waveform, which was assessed using analysis of variance (ANOVA). Mean F1 at each blood loss interval was compared to the mean at the subsequent interval. Additionally, the strength of the association between blood loss and F1 and each other marker was quantified using the marginal R2 in a linear mixed-effects model. RESULTS: PIVA derived mean F1 decreased significantly after hemorrhage of only 2% of the EBV, from 0.17 to 0.11 mm Hg, P = .001, 95% confidence interval (CI) of difference in means 0.02 to 0.10, and decreased significantly from the prior hemorrhage interval at 4%, 6%, 8%, 10%, and 12%. Log F1 demonstrated a marginal R2 value of 0.57 (95% CI 0.40–0.73), followed by PPV 0.41 (0.28–0.56) and CO 0.39 (0.26–0.58). MAP, LVEDA, and systolic pressure variation displayed R2 values of 0.31, and the remaining predictors had R2 values ≤0.2. The difference in log F1 R2 was not significant when compared to PPV 0.16 (95% CI −0.07 to 0.38), CO 0.18 (−0.06 to 0.04), or MAP 0.25 (−0.01 to 0.49) but was significant for the remaining markers. CONCLUSIONS: The mean F1 amplitude of PIVA was significantly associated with subclinical blood loss and most strongly associated with blood volume among the markers considered. This study demonstrates feasibility of a minimally invasive, low-cost method for monitoring perioperative blood loss.

Deep learning beamformers have demonstrated the ability to remove a variety of artifacts from ultrasound images in recent years. Many of these algorithms operate on channel data, where in vivo ground truth data, free of any degradation, is unavailable. Much of the existing work estimates the ground truth distribution with synthetic data. Under this framework, the domain gap between the synthetic training data and in vivo test data limits the beamformer performance on inference. In this work, we introduce a multi-step, semi-supervised approach that leverages synthetic and in vivo data in training via cross-domain cycleGANs. We evaluate the intermediate generators with VCZ curves, and demonstrate that the beamformer trained with the proposed approach achieves a CNR gain of 2.72 ± 1.40 dB and gCNR gain of 0.284 ± 0.094 over delay-and-sum in a 32-frame test cine loop.

Aim Increasing venous return during cardiopulmonary resuscitation (CPR) has been shown to improve hemodynamics during CPR and outcomes following cardiac arrest (CA). We hypothesized that a high central venous pressure amplitude (CVP-A), the difference between the maximum and minimum central venous pressure during chest compressions, could serve as a robust predictor of return of spontaneous circulation (ROSC) in addition to traditional measurements of coronary perfusion pressure (CPP) and end-tidal CO2 (etCO2) in a porcine model of CA. Methods After 10 min of ventricular fibrillation, 9 anesthetized and intubated female pigs received mechanical chest compressions with active compression/decompression (ACD) and an impedance threshold device (ITD). CPP, CVP-A and etCO2 were measured continuously. All groups received biphasic defibrillation (200 J) at minute 4 of CPR and were classified into two groups (ROSC, NO ROSC). Mean values were analyzed over 3 min before defibrillation by repeated-measures Analysis of Variance and receiver operating characteristic (ROC). Results Five animals out of 9 experienced ROSC. CVP-A showed a statistically significant difference (p = 0.003) between the two groups during 3 min of CPR before defibrillation compared to CPP (p = 0.056) and etCO2 (p = 0.064). Areas-under-the-curve in ROC analysis for CVP-A, CPP and etCO2 were 0.94 (95% Confidence Interval 0.86, 1.00), 0.74 (0.54, 0.95) and 0.78 (0.50, 1.00), respectively. Conclusion In our study, CVP-A was a potentially useful predictor of successful defibrillation and return of spontaneous circulation. Overall, CVP-A could serve as a marker for prediction of ROSC with increased venous return and thereby monitoring the beneficial effects of ACD and ITD.

Diabetic ketoacidosis is the leading cause of morbidity and mortality in children with type 1 diabetes. Management of diabetic ketoacidosis requires meticulous monitoring and treatment of severe dehydration and metabolic derangement. We present an adolescent patient who was diagnosed with diabetic ketoacidosis during spinal fusion for idiopathic scoliosis and discuss the management of this unexpected intraoperative emergency.

INTRODUCTION: Right ventricular failure (RVF) is a major cause of mortality in pulmonary hyperten-sion (PH). Mechanical circulatory support holds promise for patients with medically refractory PH, but there are no clinical devices for long-term right ventricular (RV) support. Investigations into optimal device parameters and circuit configurations for PH-induced RVF (PH-RVF) are needed.METHODS: Eleven sheep underwent previously published chronic PH model. We then evaluated a low-profile, ventricular assist device (VAD)-quality pump combined with a novel low-resistance membrane oxygenator (Pulmonary Assist Device, PAD) under one of four central cannulation strategies: right atrium-to-left atrium (RA-LA, N = 3), RA-to-pulmonary artery (RA-PA, N=3), pumpless pulmonary artery-to-left atrium (PA-LA, N = 2), and RA-to-ascending aorta (RA-Ao, N = 3). Acute-on-chronic RVF (AoC RVF) was induced, and mechanical support was provided for up to 6 hours at blood flow rates of 1 to 3 liter/min. Circuit parameters, physiologic, hemodynamic, and echocardiography data were collected.RESULTS: The RA-LA configuration achieved blood flow of 3 liter/min. Meanwhile, RA-PA and RA-Ao faced challenges maintaining 3 liter/min of flow due to higher circuit afterload. Pumpless PA-LA was flow-limited due to anatomical limitations inherent to this animal model. RA-LA and RA-Ao dem-onstrated serial RV unloading with increasing circuit flow, while RA-PA did not. RA-LA also improved left ventricular (LV) and septal geometry by echocardiographic assessment and had the lowest inotropic dependence.CONCLUSION: RA-LA and RA-Ao configurations unload the RV, while RA-LA also lowers pump speed and inotropic requirements, and improves LV mechanics. RA-PA provide inferior support for PH-RVF, while an alternate animal model is needed to evaluate PA-LA. J Heart Lung Transplant 2023;42:859-867 & COPY; 2022 International Society for Heart and Lung Transplantation. All rights reserved.

As many as one third of patients with left ventricular assist devices (LVADs) will develop at least moderate aortic regurgitation within a few years.1Soleimani B Haouzi A Manoskey A et al.Development of aortic insufficiency in patients supported with continuous flow left ventricular assist devices.ASAIO J. 2012; 58: 326-329Crossref PubMed Scopus (46) Google Scholar, 2Cowger J Pagani FD Haft JW et al.The development of aortic insufficiency in left ventricular assist device-supported patients.Circ Heart Fail. 2010; 3: 668-674Crossref PubMed Scopus (258) Google Scholar, 3Aggarwal A Raghuvir R Eryazici P et al.The development of aortic insufficiency in continuous-flow left ventricular assist device-supported patients.Ann Thorac Surg. 2013; 95: 493-498Abstract Full Text Full Text PDF PubMed Scopus (91) Google Scholar, 4Truby LK Garan AR Givens RC et al.Aortic insufficiency during contemporary left ventricular assist device support: Analysis of the INTERMACS registry.JACC Heart Fail. 2018; 6: 951-960Crossref PubMed Scopus (68) Google Scholar Aortic regurgitation decreases the efficiency of forward flow through the LVAD, leading to a decrease in oxygen supply, an increase in heart failure symptoms, recurrent hospitalizations, increased morbidity and mortality, and increased total healthcare costs. Patients with LVADs for destination therapy are often left with few options to stem the deleterious effects of aortic regurgitation. Off-label, transcatheter aortic valve replacement (TAVR) is increasingly being used as a treatment in LVAD patients with aortic regurgitation.5Kar B Prathipati P Jumean M et al.Management of aortic insufficiency using transcatheter aortic valve replacement in patients with left ventricular assist device support.ASAIO J. 2020; 66: e82-e86Crossref PubMed Scopus (7) Google Scholar, 6Rene AG Desai N Wald J et al.Transfemoral transcatheter aortic valve replacement with a self-expanding valve for severe aortic regurgitation in a patient with left ventricular assist device.J Card Surg. 2017; 32: 741-745Crossref PubMed Scopus (7) Google Scholar, 7Phan K Haswell JM Xu J et al.Percutaneous transcatheter interventions for aortic insufficiency in continuous-flow left ventricular assist device patients: A systematic review and meta-analysis.ASAIO J. 2017; 63: 117-122Crossref PubMed Scopus (33) Google Scholar, 8Yehya A Rajagopal V Meduri C et al.Short-term results with transcatheter aortic valve replacement for treatment of left ventricular assist device patients with symptomatic aortic insufficiency.J Heart Lung Transplant. 2019; 38: 920-926Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar The procedure has been described in several case reports, but its anesthetic considerations have not been described. We performed a retrospective chart review and data analysis from March 2016 through October 2019 for all patients with LVAD who underwent a TAVR at our institution due to aortic regurgitation (Table 1).Table 1Patient Demographics and Outcomes Data.IDAgeBSASexLVADLVAD IndicationDate of LVADDate of TAVRDays from LVAD to TAVRPreop StatusOutcomesComments1341.82FHWNICM: BTTSept 2015Mar 2016181HF, AKIOHT, PPD #1592691.89MHM2ICM: DTFeb 2014May 2016816HF, AKIDeath, PPD #927Hospice3622.38MHWICM & NICM: DTMay 2016Jun 201654Extremis, intubated, salvage procedureDeath, PPD #5Multiorgan failure4652.03MHWNICM: BTTApr 2017June 201781HF, ARFDeath, PPD #102HF exacerbation, CKD5702.05MHWIMC: DTJul 2016Dec 2017519HF, DoEAlive, #6726721.68FHM2NICM: DTOct 2014Apr 20181287HF, volume overloadDeath, PPD #496Mechanical fall7761.56FHWNICM: DTJun 2016Aug 2018816HF, slow VTDeath, PPD #828312.17FHM3NICM: DTJune 2018Sept 2019463HFDeath, PPD #0TAVR valve migrationAbbreviations: AKI, acute kidney injury; ARF, acute renal failure; BSA, body surface area; BTT, bridge-to-transplant; DT, destination therapy; CKD, chronic kidney disease; DoE, dyspnea on exertion; F, female; HF, heart failure; HM2, HeartMate II; HM3, HeartMate III; HW, HeartWare; ICM, ischemic cardiomyopathy; LVAD, left ventricular assist device; M, male; NICM, nonischemic cardiomyopathy; PPD, post-procedure day from TAVR; Preop, preoperative; TAVR, transcatheter aortic valve replacement; VT, ventricular tachycardia Open table in a new tab Abbreviations: AKI, acute kidney injury; ARF, acute renal failure; BSA, body surface area; BTT, bridge-to-transplant; DT, destination therapy; CKD, chronic kidney disease; DoE, dyspnea on exertion; F, female; HF, heart failure; HM2, HeartMate II; HM3, HeartMate III; HW, HeartWare; ICM, ischemic cardiomyopathy; LVAD, left ventricular assist device; M, male; NICM, nonischemic cardiomyopathy; PPD, post-procedure day from TAVR; Preop, preoperative; TAVR, transcatheter aortic valve replacement; VT, ventricular tachycardia Eight LVAD patients (6 destination therapy, 2 bridge to transplant were identified (age = 59 ± 17 years; time from LVAD to TAVR = 527 ± 429 days). Decompensated heart failure was the most common presentation with 6 subjects requiring admission for the symptoms prior to TAVR. All LVAD patients underwent general anesthesia with transesophageal echocardiography monitoring. Three methods for annulus sizing were used: transesophageal echocardiography, computed tomography, and balloon annuloplasty were used in 3, 5, and 2 patients, respectively. Medtronic CoreValves (Medtronic, Santa Rosa, CA) were deployed using the transfemoral approach with rapid ventricular pacing at 120 to 125 beats per minute. Valve oversizing was 25% ± 11%. LVAD revolutions/minute were decreased by 23% ± 8% during deployment. Two patients had moderate aortic regurgitation when their LVADs were originally placed. After TAVR, aortic regurgitation grades decreased from an average of moderate to trace in all but one patient, who had a large paravalvular leak and valve dehiscence. There was no significant change in right heart function before versus after TAVR. Five patients were extubated immediately after the procedure, and 5 were transferred to the cardiovascular intensive care unit. LVAD flow was directed by heart failure cardiology after surgery. One subject died intraoperatively during emergency surgery to repair the valve dehiscence. One patient was bridged-to-transplant on postTAVR day 159. One patient remained alive on post-TAVR day 672 with the original TAVR valve. Five patients died from nonprocedure related events within 322 days ± 388 days. Patients with an LVAD with severe aortic regurgitation presenting for TAVR offer unique challenges. First, the flow from the LVAD outflow cannula causes an opposing, proximal force against the valve during deployment. This opposing LVAD force risks valve migration into the left ventricular outflow tract or left ventricle. This risk was mitigated by decreasing LVAD flows during deployment. Second, the patients lack the heavily calcified aortic annulus seen in those with aortic stenosis that is critical for anchoring the valve.8Yehya A Rajagopal V Meduri C et al.Short-term results with transcatheter aortic valve replacement for treatment of left ventricular assist device patients with symptomatic aortic insufficiency.J Heart Lung Transplant. 2019; 38: 920-926Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar This increases the risks of paravalvular leak, valve dehiscence or embolization, as seen in one patient here. 9Athappan G Patvardhan E Tuzcu EM et al.Incidence, predictors, and outcomes of aortic regurgitation after transcatheter aortic valve replacement: Meta-analysis and systematic review Of Literature.J Am Coll Cardiol. 2013; 61: 1585-1595Crossref PubMed Scopus (589) Google Scholar,10Généreux P Head SJ Hahn R et al.Paravalvular leak after transcatheter aortic valve replacement: The new achilles' heel? A comprehensive review of the literature.J Am Coll Cardiol. 2013; 61: 1125-1136Crossref PubMed Scopus (320) Google Scholar Valve oversizing was used to provide adequate radial force to prevent valve migration and perivalvular leak. Unique concerns for evaluation of paravalvular regurgitation in the setting of an LVAD also required consideration. Due to prolonged or continuous aortic regurgitation flow associated with an LVAD, pressure half-time and pulsed Doppler evaluation of aortic diastolic flow were not useful. Further, more conservative grading scales were used to determine aortic regurgitation severity including vena contracta width ≥0.3 cm or a jet width/left ventricular outflow track width >46% at a Nyquist limit of 50 to 60 cm/s may be considered at least moderate if the aortic regurgitation jet is continuous.11Stainback RF Estep JD Agler DA et al.Echocardiography in the management of patients with left ventricular assist devices: Recommendations from the american society of echocardiography.J Am Soc Echocardiogr. 2015; 28: 853-909Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar None.

Pulmonary venous thrombosis (PVT) is a rare but potentially devastating disease state with a largely unknown incidence. The most common etiologies of PVT are secondary to complications of lung surgery, malignancy, catheter ablation for atrial fibrillation, and idiopathic causes. Diagnosis can be challenging because presenting symptoms often are vague and nonspecific, or even asymptomatic, and traditional diagnostic modalities, such as chest radiography and arterial phase computed tomography scans, are poor techniques for diagnosis. The authors present a case of a patient presenting for pulmonary thromboendarterectomy for a presumed diagnosis of chronic thromboembolic pulmonary hypertension who was found incidentally to have a PVT, on intraoperative transesophageal echocardiography. Due to significant thrombus burden, the new finding of PVT, and known association of PVT and malignancy, a biopsy of mediastinal lymph nodes was obtained, which revealed metastatic cervical carcinoma. The pulmonary endarterectomy procedure was aborted.

The Fontan procedure is performed as the final stage of palliation for patients with single-ventricle congenital heart diseases, such as tricuspid atresia, hypoplastic left-heart syndrome, or severely unbalanced atrioventricular canal defect. It creates a functional series circulation in which all pulmonary blood flow is derived from the systemic venous return that subsequently supplies ventricular preload in the absence of a subpulmonic pumping chamber. Since its inception in 1971, surgical advancement in the Fontan procedure has led to improved long-term outcomes, with transplant-free survival reaching 84% at 20 years.

Levosimendan's mechanism of action and safety profile provide optimism for potential future use in the perioperative setting of pediatric cardiac surgery. The statistically significant effects demonstrated in this review are limited to surrogates of LCOS and depend on too few studies with heterogenous methodology. Additional research with a larger controlled and multicenter study is needed, as the use of levosimendan in pediatrics is not yet demonstrated.

Purpose Right ventricular failure (RVF) is a major cause of mortality in pulmonary hypertension (PH) patients. Mechanical circulatory support holds promise for this population, but there are currently no clinical devices for long-term right ventricular (RV) support. Investigations into optimal device parameters and cannulation configurations for PH-induced RVF (PH-RVF) are needed. Methods We developed and evaluated a low-profile, ventricular assist device (VAD)-quality pump combined with a low-resistance membrane oxygenator, the Pulmonary Assist Device (PAD), for RV support in 11 sheep with chronic PH and RV hypertrophy. Four central cannulation configurations were evaluated: (1) right atrium-to-left atrium (RA-LA, N=3), (2) RA-to-pulmonary artery (RA-PA, N=3), (3) pumpless PA-to-LA (PA-LA, N=2), and (4) RA-ascending aorta (RA-Ao, N=3). Acute RVF was induced, and mechanical support was provided for up to 6 hours with blood flow rates of 1-3 L/min. Circuit, hemodynamic and echocardiographic data were collected. Results RA-LA achieved blood flow of 3 L/min within pump's operable speed, while RA-PA and RA-Ao were flow-limited due to higher circuit afterload. PA-LA could not achieve flow above 1 L/min. The oxygenator maintained a low resistance of <4 mmHg/L/min and provided oxygen delivery of 114 mL/min. RA-LA demonstrated serial RV unloading and lower inotropic dependence with increasing circuit flow. RA-Ao exhibited some RV unloading, but to a lesser extent compared to RA-LA. Meanwhile, the hemodynamic response was highly variable in RA-PA. In one trial of RA-PA, the circuit elicited severe pulmonary hemorrhage. Based on echocardiograms, only RA-LA preserved physiologic ventricular geometry. Conclusion RA-LA successfully unloads the RV at a lower pump speed, lower inotrope requirement, and improved LV filling compared to RA-Ao. RA-PA and pumpless PA-LA configurations were less viable as RV support in this study.

Conventional image quality metrics require manual selection of regions of interest and can lead to a subjective, myopic, and inefficient image assessment. We propose an automated, image-based metric that compares a test image to a reference distribution composed of Field II simulations free of phase aberration, reverberation, and off-axis scattering. By training an autoencoder on channel data of in-vivo and simulated images, we extracted a 64-dimensional feature vector for each pixel. We aggregated all pixels of an image into a 64-dimensional distribution and compressed it with K-means clustering. Lastly, we computed the similarity between test and reference distributions with the earth mover's distance (EMD). Simulation experiments demonstrate that EMD decreases monotonically as signal to clutter ratio increases. In-vivo experiments on cardiac cineloops suggest that EMD is relative consistent across frames, and appears to correlate with human perception of image quality.

Introduction: Pulmonary hypertension (PH) is a pulmonary vascular disease that progressively strains the right heart. The disease is generally irreversible and ultimately leads to right heart failure. Thus, the only long-term effective treatment is lung transplantation. Unfortunately, the donor lung pool is limited, and PH patients have one of the longest waiting times for lung transplantation. End-stage PH patients could benefit from a durable, wearable platform for mechanical circulatory support to alleviate their physiologic deficits. Toward this end, our group has established a compact mechanical support system consisting of a VAD-quality pump coupled with a membrane oxygenator. Furthermore, we previously showed that a right atrium-to-left atrium configuration provides effective support for PH-induced right ventricular failure (PH-RVF). Here, we present our proof-of-concept study using a multi-day large animal model supported by this system. Methods: Three adult sheep (weight = 84 ± 7 kg) underwent previously described PH-RVF model consisting of left pulmonary artery (PA) ligation and progressive main PA cuff occlusion. After the chronic PH model of 64 ± 6 days, the animals were cannulated for mechanical cardiopulmonary support under a right atrium-to-left atrium (RA-LA) configuration. 25Fr Biomedicus venous drainage cannula was placed in the RA via the left jugular vein, and 17-20 Fr Biomedicus cannula was placed in the LA through a mini left thoracotomy. The circuit consisted of a HeartAssist5 (ReliantHeart, Houston TX) pump and Nautilus (N=3, MC3, Ann Arbor, Michigan) as a membrane oxygenator. The animal was then recovered in a custom-designed stanchion cage for chronic monitoring. Circuit parameters were recorded, and blood samples were drawn daily. Results: Three sheep with PH were used for this preliminary study (induced RV systolic pressure 93 ± 10 mmHg before cannulation). Two of the three studies lasted for the planned duration of seven days. One study was terminated early on the second post-operative day (POD) due to intrathoracic bleeding. Among the two seven-day trials, the HeartAssist5 pump provided stable flow of 2.69 ± 0.43 L/min at pump speed of (11.97 ± 0.68) x 103 RPM, while the PA flow was 3.52 ± 1.09 L/min (Figure 1A) (i.e., the circuit offloaded about 43% of the total cardiac output). The oxygenator circuit provided sufficient gas exchange and maintained acid-base balance at a minimal sweep gas flow of 0.5 L/min (Figure 1B, C). One sheep was able to ambulate with the wearable support system on the seventh day of mechanical support (Figure 2). Conclusion: This study serves as a proof-of-concept for long-term wearable support for PH-RVF patients. The circuit could consistently offload over 40% of the cardiac output. Left atrial cannula size is likely the limiting factor for maximal achievable blood flow with this system. Further innovation is needed in surgical techniques to implement circuit support. Figure 1. Longitudinal trends during multi-day support study: A) Circuit and pulmonary artery blood flows; B) Sweep gas flow rate; C) Blood lactate level. N = 2-3 for Days 0-2, and N =2 for Days 3-7. Figure 2. Pulmonary hypertension sheep ambulating with the wearable mechanical support technology.