Multiscale modelling of Potts shunt as a potential palliative treatment for suprasystemic idiopathic pulmonary artery hypertension: a paediatric case study

Potts shunt (PS) was suggested as palliation for patients with suprasystemic pulmonary arterial hypertension (PAH) and right ventricular (RV) failure. PS, however, can result in poorly understood mortality. Here, a patient-specific geometrical multiscale model of PAH physiology and PS is developed for a paediatric PAH patient with stent-based PS. In the model, 7.6mm-diameter PS produces near-equalisation of the aortic and PA pressures and $$Q_p/Q_s$$ Q p / Q s (oxygenated vs deoxygenated blood flow) ratio of 0.72 associated with a 16% decrease of left ventricular (LV) output and 18% increase of RV output. The flow from LV to aortic arch branches increases by 16%, while LV contribution to the lower body flow decreases by 29%. Total flow in the descending aorta (DAo) increases by 18% due to RV contribution through the PS with flow into the distal PA branches decreasing. PS induces 18% increase of RV work due to its larger stroke volume pumped against lower afterload. Nonetheless, larger RV work does not lead to increased RV end-diastolic volume. Three-dimensional flow assessment demonstrates the PS jet impinging with a high velocity and wall shear stress on the opposite DAo wall with the most of the shunt flow being diverted to the DAo. Increasing the PS diameter from 5mm up to 10mm results in a nearly linear increase in post-operative shunt flow and a nearly linear decrease in shunt pressure-drop. In conclusion, this model reasonably represents patient-specific haemodynamics pre- and post-creation of the PS, providing insights into physiology of this complex condition, and presents a predictive tool that could be useful for clinical decision-making regarding suitability for PS in PAH patients with drug-resistant suprasystemic PAH.

A multicenter prospective registry of Borden type I dural arteriovenous fistula: results of a 3-year follow-up study

Purpose Although intracranial dural arteriovenous fistula (DAVF) without retrograde leptomeningeal venous drainage (Borden type I) is reported to have a benign nature, no study has prospectively determined its clinical course. Here, we report a 3-year prospective observational study of Borden type I DAVF. Methods From April 2013 to March 2016, consecutive patients with DAVF were screened at 13 study institutions. We collected data on baseline characteristics, clinical symptoms, angiography, and neuroimaging. Patients with Borden type I DAVF received conservative care while palliative intervention was considered when the neurological symptoms were intolerable, and were followed at 6, 12, 24, and 36 months after inclusion. Results During the study period, 110 patients with intracranial DAVF were screened and 28 patients with Borden type I DAVF were prospectively followed. None of the patients had conversion to higher type of Borden classification or intracranial hemorrhage during follow-up. Five patients showed spontaneous improvement or disappearance of neurological symptoms (5/28, 17.9%), and 5 patients showed a spontaneous decrease or disappearance of shunt flow on imaging during follow-up (5/28, 17.9%). Stenosis or occlusion of the draining sinuses on initial angiography was significantly associated with shunt flow reduction during follow-up (80.0% vs 21.7%, p = 0.02). Conclusion In this 3-year prospective study, patients with Borden type I DAVF showed benign clinical course; none of these patients experienced conversion to higher type of Borden classification or intracranial hemorrhage. The restrictive changes of the draining sinuses at initial diagnosis might be an imaging biomarker for future shunt flow reduction.

Effects of Patent Ductus Arteriosus on the Hemodynamics of Modified Blalock–Taussig Shunt Based on Patient-Specific Simulation

The question of preserving the patent ductus arteriosus (PDA) during the modified Blalock–Taussig shunt (MBTS) procedure remains controversial. The goal of this study was to investigate the effects of the PDA on the flow features of the MBTS to help with preoperative surgery design and postoperative prediction. In this study, a patient with pulmonary atresia and PDA was included. A patient-specific three-dimensional model was reconstructed, and virtual surgeries of shunt insertion and ductus ligation were performed using computer-aided design. Computational fluid dynamics was utilized to analyze the hemodynamic parameters of varied models based on the patient-specific anatomy and physiological data. The preservation of the PDA competitively reduced the shunt flow but increased total pulmonary perfusion. The shunt flow and ductal flow collided, causing significant and complicated turbulence in the pulmonary artery where low wall shear stress, high oscillatory shear index, and high relative residence time were distributed. The highest energy loss was found when the PDA was preserved. The preservation of PDA is not recommended during MBTS procedures because it negatively influences hemodynamics. This may lead to pulmonary overperfusion, inadequate systemic perfusion, and a heavier cardiac burden, thus increasing the risk of heart failure. Also, it seems to bring no benefit in terms of reducing the risk for thrombosis.

Gradual dilatation of an occluded transverse sinus associated with dural arteriovenous fistula after balloon angioplasty with sinus packing: A case report

Background There is no consensus as to whether balloon angioplasty alone or stent placement is effective for sinus occlusion associated with dural arteriovenous fistula (DAVF). Herein, we first report a case of transverse sinus occlusion associated with DAVF in which gradual sinus dilatation was observed after balloon angioplasty with embolization of the affected sinus with shunt flow. Case presentation A 69-year-old man presented with executive dysfunction. Magnetic resonance imaging revealed left transverse sinus–sigmoid sinus DAVF with occlusion of the left jugular vein and right transverse sinus. Before endovascular treatment, the patient had symptomatic epilepsy and subarachnoid hemorrhage. Retrograde leptomeningeal venous drainage disappeared with packing of the left transverse sinus–sigmoid sinus. Subsequently, balloon angioplasty of the right occluded transverse sinus was performed to maintain the normal venous drainage and remaining shunt outflow. Dilatation of the right transverse sinus was poor immediately after surgery. However, angiography after 10 days and 6 months revealed gradual dilatation of the right transverse sinus. Conclusion Sinus occlusion, which is thought to be caused by sinus hypertension associated with DAVF rather than chronic organized thrombosis or thrombophilia, may dilate over time after balloon angioplasty and shunt flow reduction if occluded sinus is necessary for facilitating normal venous drainage.

A case report of unexpected right-to-left shunt under mechanical support for post-infarction ventricular septal defect: evaluation with haemodynamic simulator

Background Post-myocardial infarction ventricular septal defect (PIVSD) is a complication of acute myocardial infarction with high mortality. A percutaneous left ventricular assist device, Impella, is currently used in maintaining haemodynamic stability in PIVSD. Case summary A 65-year-old man was transferred to our hospital for treatment of acute myocardial infarction of the proximal right coronary artery. Percutaneous intervention was performed but haemodynamic instability continued. At 10 days after onset, the patient was diagnosed with PIVSD by echocardiogram. To stabilize haemodynamics, we initiated venoarterial extracorporeal membrane oxygenation (ECMO). Three days after ECMO initiation, pulmonary congestion increased and an echocardiogram revealed closed aortic valve and spontaneous echo contrast at the aortic root. After an Impella 2.5 was inserted for unloading of the left ventricle, the oxygenation level and cardiac function rapidly declined. Unexpectedly, an echocardiogram showed a right-to-left shunt (to-and-fro pattern) via PIVSD. By increasing the ECMO and decreasing Impella flow, the shunt flow changed to left-to-right, and oxygenation level and cardiac function improved. Ten days after ECMO was started, elective surgical repair was successfully performed. Conclusion ECPELLA (ECMO + Impella) can offset the adverse effects of isolated ECMO support and reduce the PIVSD shunt flow. However, the risk of right-to-left shunt has not been reported, and ECPELLA caused a right-to-left shunt with deoxygenated systemic perfusion in the present case. A simulation study indicated that the right ventricular failure in PIVSD may pose a risk for right-to-left PIVSD shunt under Impella support.

Prediction of hemodynamics after atrial septal defect closure using a framework of circulatory equilibrium in dogs

We developed a framework to predict the impact of atrial septal defect (ASD) closure on hemodynamics by incorporating ASD shunt flow into the framework of circulatory equilibrium. The proposed framework accurately predicted hemodynamics after ASD closure. Patient-specific prediction of hemodynamics may be useful for safety management of ASD closure.

Reliability of the radiopharmaceutical shunt flow study for the detection of a CSF shunt malfunction in the presence of stable ventricular size

OBJECTIVEThe authors sought to determine the reliability of a radiopharmaceutical (RP) shunt flow study for the detection of a CSF-diverting shunt malfunction in the presence of stable ventricular size.METHODSAfter the authors obtained IRB approval, all CSF RP shunt flow studies done between January 1, 2014, and January 1, 2019, in pediatric patients at Children’s Hospital Los Angeles were identified. Included in the study were only those patients in whom an MRI or CT scan was done during the hospital admission for shunt malfunction and showed no increase in ventricular size compared with the most recent prior MRI or CT scan when the patient was asymptomatic. Data recorded for analysis were patient age and sex, etiology of the hydrocephalus, shunt distal site, nonprogrammable versus programmable valve, operative findings if the shunt was revised, and follow-up findings for a minimum of 90 days after admission. The RP shunt flow study consisted of tapping the reservoir and injecting technetium-99m DTPA according to a set protocol.RESULTSThe authors identified 146 RP flow studies performed in 119 patients meeting the above criteria. Four of the 146 RP studies (3%) were nondiagnostic secondary to technical failure and were excluded from statistical analysis. Of the 112 normal flow studies, operative intervention was not undertaken in 102 (91%). The 10 (9%) remaining normal studies were performed in patients who underwent operative intervention, in which 8 patients had a proximal obstruction, 1 had a distal obstruction, and 1 patient had no obstruction. Of the 30 patients with abnormal flow studies, symptoms of shunt malfunction subsided in 9 (30%) patients and these patients did not undergo operative intervention. Of the 21 (70%) operated patients, obstruction was proximal in 9 patients and distal in 5, and for 7 patients the shunt tubing was either fractured or disconnected. Regression analysis indicated a significant association between the flow study interpretation and the odds for shunt revision (OR 27, 95% CI 10–75, p < 0.0001). No other clinical variables were significant. The sensitivity of a shunt flow study alone for detection of shunt malfunction in cases with stable ventricular size was the same as a shunt flow study plus an MRI or CT (70% vs 70%), but performing a shunt flow in addition to MRI or CT did increase the specificity from 92% to 100% and the accuracy from 87% to 94%.CONCLUSIONSRP shunt flow studies were of definite value in deciding whether to operatively intervene in patients with symptoms of shunt malfunction in whom no change in ventricular size was detected on current MRI or CT scans compared to scans obtained when the patients were asymptomatic.

Neonatal hypertension caused by left-to-right shunt flow through a patent ductus arteriosus in a premature infant

ObjectivesThough it is rare and challenging to study, neonatal hypertension (HTN) has been explored and studied by many pediatricians. There were some causes reported in preterm infants such as renal diseases and bronchopulmonary dysplasia.Case presentationWe report a premature female infant who was born at a gestational age of 25 + 6 weeks and developed systemic hypertension on the day of a gestation age of 30 + 3 weeks. This case had a rare cause which involved high-normal serum aldosterone level that could possibly indicate hyperaldosteronism and over-stimulation of renin–angiotensin–aldosterone system (RAAS). We believe elevation of serum aldosterone was caused by a left-to-right shunt flow through a patent ductus arteriosus. Hypertension due to a patent ductus arteriosus sounds like a paradox. However, in our case, the shunt flow was shown to be a possible cause of the systemic hypertension. Surgical closure of the shunt was done and the hypertension resolved. We evaluated serum aldosterone levels and plasma renin activities both, before and after the closure to look for a possible cause.ConclusionsNeonatologist often treats systemic hypertensive infants considering possible causes in order to prevent hypertensive crisis. Our case shows that possibility of hyperaldosteronism and (RAAS) over-stimulation should be considered as causes in case of severe systemic hypertension in preterm infants with large left-to-right shunt flows.

P248 Changes of atrial septum defect caused by posture during three-dimensional transesophageal echocardiography ( a case of Platypnea-orthodeoxia syndrome)

Background Platypnea-Orthodeoxia syndrome (POS) is a rare phenomenon which is characterized postural hypoxia due to the intracardiac shunt from right to left through a patent foramen ovale, an atrial septal defect or a pulmonary arteriovenous malformation. POS is often underestimated because the hypoxia by postural change is difficult to be detected. We evaluated three-dimensional transesophageal echocardiography (TEE) to diagnose POS in an elderly patient. Case report A 84-year-old woman suffered from repetitive syncope for several years. She undertook twelve leads electrocardiogram (ECG), screening transthoracic echocardiography (TTE), twenty-four hours ECG and treadmill stress ECG, however, the cause of syncope was not identified. After another syncope event happened, she was transferred to the emergency room. Then, the hypoxia caused by sitting position was pointed out for the first time. Her hypoxia was improved by supine position and oxygen administration. TTE demonstrated no right heart enlargement. Shunt flow was suspected on her atrial septum; however, it was difficult to reveal it by TTE because of her obesity. Therefore, she underwent intravenous saline injection test. In the decubitus position, an intravenous injection of saline under Valsalva maneuver revealed the shunt flow from the right atrium to the left atrium. Her arterial oxygen saturation (SpO2) was 95%. In the sitting position, a visible shunt flow was observed, then her SpO2 dropped to 85%. By TEE, the shunt hole was found in the oval fossa of the atrial septum. TEE was evaluated by different positions. The atrial defect hole became larger in the sitting position (area 1.05cm2) than in the supine position (area 0.43cm2). As a result, the postural change to sitting revealed Platypnea-Orthodeoxia syndrome associated with ASD. The pulmonary blood flow/systemic blood flow ratio (Qp/Qs) was estimated at 1.6. After surgical ASD closure, she was discharged without any symptoms. Conclusion Unclearness of TTE and the absence of a right heart overload may lead to misdiagnosis of POS. If a syncope patient caused hypoxia in the only sitting position, detailed echocardiography should be needed to rule out a diagnosis of POS. This is considerably valuable case of three-dimensional TEE confirmed the changes of ASD size by postural change. Abstract P248 Figure.