Ventilator avoidance among critically ill COVID-19 patients with acute respiratory distress syndrome.

OBJECTIVE: To determine the incidence and significance of ventilator avoidance in patients with critical coronavirus disease 2019 (COVID-19). METHODS: This prospective observational cohort study evaluated hospital mortality and 1-year functional outcome among critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated acute respiratory distress syndrome (ARDS). The explanatory variable was ventilator avoidance, modeled as 'initial refusal' of intubation (yes/no). Modified Rankin Scale (mRS) scores were obtained from surviving patients (or their surrogates) via phone or email questionnaire. RESULTS: Among patients for whom intubation was recommended (n = 102), 40 (39%) initially refused (95% confidence interval [CI] 30%, 49%). The risk of death was 79.3% (49/62) in those who did not initially refuse intubation compared with 77.5% (31/40) in those who initially refused, with an adjusted odds ratio for death of 1.27 (95% CI 0.47, 3.48). The distribution of 1-year mRS scores was not significantly different between groups. CONCLUSION: Among critically ill patients with COVID-19-associated ARDS, ventilator avoidance was common, but was not associated with increased in-hospital mortality or 1-year functional outcome.

Data-driven computational models of ventricular-arterial hemodynamics in pediatric pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a complex disease involving increased resistance in the pulmonary arteries and subsequent right ventricular (RV) remodeling. Ventricular-arterial interactions are fundamental to PAH pathophysiology but are rarely captured in computational models. It is important to identify metrics that capture and quantify these interactions to inform our understanding of this disease as well as potentially facilitate patient stratification. Towards this end, we developed and calibrated two multi-scale high-resolution closed-loop computational models using open-source software: a high-resolution arterial model implemented using CRIMSON, and a high-resolution ventricular model implemented using FEniCS. Models were constructed with clinical data including non-invasive imaging and invasive hemodynamic measurements from a cohort of pediatric PAH patients. A contribution of this work is the discussion of inconsistencies in anatomical and hemodynamic data routinely acquired in PAH patients. We proposed and implemented strategies to mitigate these inconsistencies, and subsequently use this data to inform and calibrate computational models of the ventricles and large arteries. Computational models based on adjusted clinical data were calibrated until the simulated results for the high-resolution arterial models matched within 10% of adjusted data consisting of pressure and flow, whereas the high-resolution ventricular models were calibrated until simulation results matched adjusted data of volume and pressure waveforms within 10%. A statistical analysis was performed to correlate numerous data-derived and model-derived metrics with clinically assessed disease severity. Several model-derived metrics were strongly correlated with clinically assessed disease severity, suggesting that computational models may aid in assessing PAH severity.

Healthcare-acquired coronavirus disease 2019 (COVID-19) is less symptomatic than community-acquired disease among healthcare workers.

OBJECTIVE: We hypothesized that healthcare workers (HCWs) with high-risk exposures outside the healthcare system would have less asymptomatic coronavirus 2019 (COVID-19) disease and more symptoms than those without such exposures. DESIGN: A longitudinal point prevalence study was conducted during August 17-September 4, 2020 (period 1) and during December 2-23, 2020 (period 2). SETTING: Community based teaching health system. PARTICIPANTS: All HCWs were invited to participate. Among HCWs who acquired COVID-19, logistic regression models were used to evaluate the adjusted odds of asymptomatic disease using high-risk exposure outside the healthcare system as the explanatory variable. The number of symptoms between exposure groups was evaluated with the Wilcoxon rank-sum test. The risk of seropositivity among all HCS by work exposure was evaluated during both periods. INTERVENTIONS: Survey and serological testing. RESULT: Seroprevalence increased from 1.9% (95% confidence interval [CI], 1.2%-2.6%) to 13.7% (95% CI, 11.9%-15.5%) during the study. Only during period 2 did HCWs with the highest work exposure (versus low exposure) have an increased risk of seropositivity (risk difference [RD], 7%; 95% CI, 1%-13%). Participants who had a high-risk exposure outside of work (compared to those without) had a decreased probability of asymptomatic disease (odds ratio [OR], 0.38; 95% CI, 0.16-0.86) and demonstrated more symptoms (median 3 [IQR, 2-6] vs 1 [IQR, 0-4]; P = .001). CONCLUSIONS: Healthcare-acquired COVID-19 increases the probability of asymptomatic or mild COVID-19 disease compared to community-acquired disease. This finding suggests that infection prevention strategies (including masks and eye protection) may be mitigating inoculum and supports the variolation theory in COVID-19.

Characterization of Post-Operative Hemodynamics Following the Norwood Procedure Using Population Data and Multi-Scale Modeling.

Children with hypoplastic left heart syndrome (HLHS) must undergo multiple surgical stages to reconstruct the anatomy to a sustainable single ventricle system. Stage I palliation, or the Norwood procedure, provides circulation to both pulmonary and systemic vasculature. The aorta is reconstructed and attached to the right ventricle and a fraction of systemic flow is redirected to the pulmonary arteries (PAs) through a systemic-to-PA shunt. Despite abundant hemodynamic data available 4-5 months after Norwood palliation, data is very scarce immediately following stage I. This data is critical in determining post-operative success. In this work, we combined population data and computational fluid dynamics (CFD) to characterize hemodynamics immediately following stage I (post-stage I) and prior to stage II palliation (pre-stage II). A patient-specific model was constructed as a baseline geometry, which was then scaled to reflect population-based morphological data at both time-points. Population-based hemodynamic data was then used to calibrate each model to reproduce blood flow representative of HLHS patients. The post-stage I simulation produced a PA pressure of 22 mmHg and high-frequency oscillations within the flow field indicating highly disturbed hemodynamics. Despite PA mean pressure dropping to 14 mmHg, the pre-stage II model also produced high-frequency flow components and PA wall shear stress increases. These suboptimal conditions may be necessary to ensure adequate PA flow throughout the pre-stage II period, as the shunt becomes relatively smaller compared to the patient's somatic growth. In the future, CFD can be used to optimize shunt design and minimize these suboptimal conditions.

Use of Hemodynamic Ramp Study to Optimize Continuous-Flow Ventricular Assist Device in a Fontan Patient.

The utility of hemodynamic ramp studies in single ventricle patients supported by continuous flow left ventricular assist devices (CF-LVADs) is largely unknown. We report the novel use of the hemodynamic ramp test to optimize a 26 year-old Fontan-palliated single-ventricle patient supported with a continuous-flow ventricular assist device (Heartware HVAD). Modest improvements in Fontan hemodynamics resulted in significant and persistent clinical improvement and symptomatic relief.

Reproducing Patient-Specific Hemodynamics in the Blalock-Taussig Circulation Using a Flexible Multi-Domain Simulation Framework: Applications for Optimal Shunt Design.

For babies born with hypoplastic left heart syndrome, several open-heart surgeries are required. During Stage I, a Norwood procedure is performed to construct an appropriate circulation to both the systemic and the pulmonary arteries. The pulmonary arteries receive flow from the systemic circulation, often using a Blalock-Taussig (BT) shunt between the innominate artery and the right pulmonary artery. This procedure causes significantly disturbed flow in the pulmonary arteries. In this study, we use computational hemodynamic simulations to demonstrate its capacity for examining the properties of the flow through and near the BT shunt. Initially, we construct a computational model which produces blood flow and pressure measurements matching the clinical magnetic resonance imaging (MRI) and catheterization data. Achieving this required us to determine the level of BT shunt occlusion; because the occlusion is below the MRI resolution, this information is difficult to recover without the aid of computational simulations. We determined that the shunt had undergone an effective diameter reduction of 22% since the time of surgery. Using the resulting geometric model, we show that we can computationally reproduce the clinical data. We, then, replace the BT shunt with a hypothetical alternative shunt design with a flare at the distal end. Investigation of the impact of the shunt design reveals that the flare can increase pulmonary pressure by as much as 7% and flow by as much as 9% in the main pulmonary branches, which may be beneficial to the pulmonary circulation.

Spontaneous aberrant right subclavian arterio-oesophageal fistula in a previously healthy child.

An aberrant right subclavian artery arising from a left aortic arch is the most frequently described congenital aortic arch anomaly, occurring in 0.5 to 2.3% of the general population. Despite the retro-oesophageal course of the aberrant subclavian artery, an arterio-oesophageal fistula is an uncommon finding, only previously reported as a very rare complication in critically ill patients with oesophageal instrumentation or foreign body ingestion. We describe a unique case of a spontaneous aberrant right subclavian arterio-oesophageal fistula without an inciting event in a 17-month-child.

Transcatheter occlusion of large pulmonary arteriovenous malformations using multiple devices in a neonate.

Pulmonary arteriovenous malformations (PAVMs) are usually well-tolerated hemodynamically. Rarely, they cause severe neonatal cyanosis, requiring urgent treatment. We report the use of multiple transcatheter vascular occlusion devices to reduce right-to-left shunting in a neonate with multiple, large PAVMs.

Transcatheter occlusion of a persistent left superior vena cava to the left atrium using the transseptal approach.

A persistent left superior vena cava (LSVC) is a common venous anomaly, occurring in up to 10% of patients with congenital heart defects. Usually, a LSVC drains into the coronary sinus, then to the right atrium. The LSVC can drain directly to the left atrium, resulting in a right-to-left shunt and systemic desaturation. Historically, surgery has been used to address this lesion. Transcatheter occlusion of the LSVC is an alternative to surgery. We report the novel use of the transseptal approach to access the LSVC, and device occlusion using the Amplatzer Vascular Plug-II.

Transcatheter retrieval of an embolized methylmethacrylate glue fragment adherent to the right atrium using bidirectional snares.

We report the successful transcatheter retrieval of a 6-cm long, rigid methylmethacrylate glue fragment that embolized from a vertebral body to the right atrium. The glue fragment was adherent to the right atrial wall. Two snares were needed, advanced from opposite directions, to carefully separate the glue fragment from the atrial wall, then align it in a linear fashion directly into the sheath for an uneventful removal.

Descending aorta thrombus in a neonate mimicking coarctation of the aorta: mechanical thrombectomy using the AngioJet(®) catheter.

A 5-day-old neonate presented in shock, with signs and symptoms of severe coarctation of the aorta. He was diagnosed with a patent aortic arch, and a completely thrombosed abdominal aorta. The authors report the successful transcatheter removal of the entire thrombus using the AngioJet(®) Thrombectomy system. This represents the first published use of the AngioJet(®) catheter in the aorta of a pediatric patient.

Outcomes of transcatheter occlusion of patent ductus arteriosus in infants weighing ≤ 6 kg.

OBJECTIVES: We sought to analyze the outcomes of transcatheter patent ductus arteriosus (PDA) occlusion using a variety of devices in infants weighing ≤6 kg. BACKGROUND: Indications for transcatheter closure of a PDA in infancy include congestive heart failure and/or failure to thrive. Devices available for small infants may be problematic for various reasons, including sheath size, stiffness of delivery system, and anchoring and retrievability characteristics of the device. The Amplatzer Ductal Occluder is approved by U.S. Food and Drug Administration for children weighing >6 kg and older than 6 months of age. METHODS: We performed a multicenter, retrospective analysis of children weighing ≤6 kg in whom transcatheter PDA occlusion was attempted between January 1995 and November 2005 at Texas Children's Hospital and January 2001 to November 2005 at Children's Hospital of San Diego. RESULTS: A total of 62 patients underwent attempted closure. The mean age at catheterization was 4.7 ± 2.8 months with a mean weight at catheterization of 4.6 ± 0.9 kg. Successful device placement was achieved in 58 of 62 patients (94%). Among those receiving a device, complete occlusion was noted in all 58 patients at either catheterization or last available follow-up. CONCLUSIONS: Percutaneous closure of PDA should be considered even in infants ≤6 kg.

Simultaneous stent implantation to treat bifurcation stenoses in the pulmonary arteries: Initial results and long-term follow up.

BACKGROUND: Balloon angioplasty of bifurcating pulmonary artery (PA) stenoses is often inadequate, and stent treatment often requires simultaneous implantation of two stents. This study evaluates initial results and long-term follow up of transcatheter stent placement in bifurcating PAs. METHODS: This is a retrospective review of patients (pts) who had bifurcating PA stents placed in main and lobar branches from 1993 to 2007. RESULTS: Forty-nine pts had bifurcating PA stents placed at a median age of 10.9 years (range 1-43 years). The mean minimum vessel diameter increased from 5.7 +/- 2.5 mm to 11.0 +/- 3.6 mm (P < 0.001), the mean gradient across the stenoses decreased from 37.0 +/- 26.9 to 9.2 +/- 13 mm Hg (P < 0.001), whereas the mean RV:FA ratio decreased from 0.76 +/- 0.29 to 0.53 +/- 0.24 (P < 0.001). There was one death due to severe pulmonary hemorrhage. F/U data were available in 38 pts (mean duration 6.3 +/- 4.1 years, range 1.2-13.1 years). Thirty pts underwent repeat catheterizations (mean 2.3 +/- 2.2 years poststent), with 26 requiring further interventions: Fifteen had balloon angioplasty alone and 11 had additional stents placed. There were no complications at f/u catheterization. Six pts underwent further palliative surgeries, although none for repair of branch PA stenoses. CONCLUSIONS: Simultaneous transcatheter placement of bifurcating PA stents provides immediate gradient relief of bifurcating stenoses in the proximal or lobar branch PAs and reduces RV systolic pressure. Further interventions can be safely performed in future procedures, and the presence of stents does not complicate future surgeries.

Transcatheter closure of patent ductus arteriosus and aorto-pulmonary vessels using non-ferromagnetic Inconel MReye embolization coils.

OBJECTIVES: We report the use of non-ferromagnetic embolization coils for transcatheter PDA closure. BACKGROUND: Transcatheter patent ductus arteriosus (PDA) closure has been performed for 40 years. A number of devices have been used with varying degrees of success. Gianturco embolization coils have been used frequently since 1992 with excellent results. These coils are a stainless steel alloy, and create an artifact when subsequent MRI imaging is performed. METHODS: Eight patients underwent right and left heart catheterization and transcatheter PDA closure. Angiography displayed a PDA with left to right shunting. The minimum PDA diameter was measured. An Inconel MReye coil was implanted using standard retrograde technique. A postimplant angiogram was performed. Evaluations were performed the following morning and after 2 months. RESULTS: The median age was 5.5 years, median weight was 24 kg. The PDA minimum diameter was 1.7 mm (range 1.4-2.4 mm), with a median Qp:Qs=1.33:1. In all patients, the PDA was completely immediately closed using one Inconel coil. Two patients also had a small aorto-pulmonary collateral vessel that was occluded using a separate Inconel coil. All patients had follow-up evaluation the following day; the PDA remained completely occluded and there was no obstruction of the pulmonary artery branches or descending aorta. Seven patients had subsequent follow-up and echocardiograms; the PDA remained completely occluded. There were no complications. CONCLUSION: The Inconel MReye coil is safe and effective for coil occlusion of small PDA and aorto-pulmonary vessels. Additional studies are needed to define the maximum vessel diameter for Inconel coil occlusion.

Methemoglobinemia in a young man.

In patients who have cyanosis and dyspnea that are unrelated to a cardiopulmonary cause, 1 rare possible diagnosis is methemoglobinemia. This condition is generally asymptomatic, even when the methemoglobin level is as high as 40% of the total hemoglobin value. In the patient described herein, extensive pulmonologic and cardiologic investigations failed to yield the correct diagnosis, which was finally made on the basis of physical findings and arterial blood-gas analysis. Later, a DNA analysis, reported separately by others, showed that the patient's methemoglobinemia was caused by a novel mutation of the cytochrome b5 reductase gene.

Atrial septostomy improves survival in select patients with pulmonary hypertension.

BACKGROUND: Atrial septostomy is a palliative treatment for patients with pulmonary hypertension (PHTN) refractory to vasodilator therapy. Limited data exist in the pediatric population and in patients with repaired congenital heart defects. METHODS: We performed a retrospective analysis of hemodynamic and symptomatic changes in patients with PHTN who underwent an atrial septostomy at our institution. RESULTS: Forty-six atrial septostomies were performed on 43 patients. Patient ages ranged from 0.3 to 30 years (median 12.5). Of 43 patients, 29 had primary PHTN, 10 had PHTN associated with repaired congenital heart defects, and 4 had other secondary causes of PHTN. Mean baseline pulmonary vascular resistance was 35 +/- 17 Wood units, and mean pulmonary artery pressure was 74 +/- 19 mm Hg. Patients surviving > or = 30 days had immediate improvement in cardiac index (from 2.3 to 2.9 L x min(-1) x m(-2), P < .0001), right atrial pressure (RAp) (from 9.9 to 8.3 mm Hg, P < .05), and oxygen delivery (from 424 to 491 mL O2 per minute, P < .01), with a decrease in systemic oxygen saturation (from 93% to 86%, P < .001). Pulmonary artery pressure was unchanged (P = .3). New York Heart Association class and symptoms of syncope improved (P < .01). Event-free survival at 1, 2, and 3 years was 84%, 77%, and 69%, respectively. Using the National Institutes of Health Registry model, predicted survival probability significantly improved (P < .001). Ten patients (22%) died within 30 days of catheterization. Mortality was associated with preceding decompensations in the intensive care unit (6/10, P < .001) and a higher RAp (21.4 vs 9.8 mm Hg, P < .001). CONCLUSIONS: Atrial septostomy provides symptomatic and hemodynamic improvement in cardiac index and RAp. Risk of septostomy is increased in patients with preceding decompensation or a RAp > 18 mm Hg.

Arterial pulse wave analysis: An accurate means of determining cardiac output in children.

OBJECTIVE: Cardiac output is a useful measure of myocardial performance. Standard methods of determining cardiac output are not without risk and can be problematic in children. Arterial pulse wave analysis (PulseCO), a novel, minimally invasive cardiac output determination technique, offers the advantage of continuous monitoring, convenience, and low risk. This technique has not been validated in children. The purpose of this study was to validate PulseCO as an accurate means of noninvasively determining real-time cardiac output in children. DESIGN: Prospective, single-center evaluation. SETTING: Children's hospital. PATIENTS: Any child with a structurally normal heart, undergoing hemodynamic evaluation in the cardiac catheterization laboratory, was included. INTERVENTIONS: A prograde right heart catheterization was performed, and cardiac output was determined using the thermodilution technique, via placement of a pulmonary arterial catheter. MEASUREMENTS AND MAIN RESULTS: Thermodilution results were compared with continuous real-time cardiac output measurements obtained with the PulseCO system, and they were then analyzed by standard correlation techniques and Bland-Altman analysis. Twenty patients were evaluated with a median age of 10.5 yrs and a median weight of 25 kg. The mean thermodilution cardiac index was 3.3 +/- 0.9 L/min/m, whereas the mean PulseCO cardiac index was 3.1 +/- 0.9 L/min/m. Standard Pearson correlation tests revealed a correlation coefficient of .94 (p < .001). Bland-Altman analysis revealed excellent clinical agreement with a mean difference of 0.19 L/min/m and a precision of 0.28 L/min/m at 2 sd. CONCLUSIONS: Arterial pulse wave analysis by the PulseCO system provides a novel, minimally invasive method of determining real-time cardiac output in children.

Complex pulmonary atresia in a neonate: successful surgical palliation for right pulmonary artery arising from the right main coronary artery.

We describe the case of a 3-week-old infant who was diagnosed with pulmonary atresia, a ventricular septal defect, and discontinuous pulmonary arteries. The pulmonary artery anatomy was delineated by angiography: the right pulmonary artery arose from the proximal right coronary artery, and the left pulmonary artery arose from a left ductus arteriosus. This case illustrates the importance of careful delineation of the anatomy in complex pulmonary atresia before surgical intervention.

Impact of transcatheter occlusion of a patent ductus arteriosus on atrial septal defect diameter in children.

BACKGROUND: A persistent patent ductus arteriosus (PDA) may delay closure of a coexisting atrial septal defect (ASD) due to volume loading and enlargement of the left atrium. The purpose of this study was to investigate the natural history of ASD size in patients with a PDA following transcatheter PDA occlusion. METHODS: All patients with an ASD and a PDA who underwent transcatheter PDA occlusion at Texas Children's Hospital were identified. Patients with ASD diameter <3 mm, or additional cardiac defects were excluded. Eight patients (7 females) with small- to moderate-sized ASDs and a PDA were identified. Patient demographics, echocardiographic data, and cardiac catheterization data were recorded. Data were analyzed by 1-tailed t-test. RESULTS: Following PDA occlusion, ASD diameter decreased in 6 of 8 patients by a mean of 3.8 mm (+/-2.3 mm), including 2 that closed. The median duration of follow-up was 689 days. One ASD remained unchanged and 1 increased in size. The mean maximum ASD diameter decreased from 6.4 mm (+/-2.2 mm) to 3.9 mm (+/-3.4 mm) (P = .03). Two patients underwent subsequent transcatheter ASD occlusion. CONCLUSION: Following transcatheter PDA occlusion, small- to moderate-sized ASDs have significant probability to decrease in size, and possibly close. In infants and children, we recommend transcatheter PDA occlusion, and serial follow-up of the size of the ASD. This will allow many small- to moderate-sized ASDs to either close, or become smaller, obviating the need for future intervention.