Circulatory Assistance Research Articles

Percutaneous circulatory assistance in an interventional cardiology centre without on-site cardiac surgery.

Percutaneous extracorporeal membrane oxygenation (ECMO) has been developed thanks to the progress in the field of cannulation, but still justifies the presence of an on-site cardiac resuscitation department. Corsica is a French island without an on-site cardiac surgery department. To evaluate the percutaneous ECMO programme in Corsica. All patients who received ECMO at the Bastia Hospital Centre between 01 January 2016 and 30 April 2022 were included. ECMO was implanted in 39 patients. The mean age was 52.7years, with male predominance (84.6%). The majority of veno-arterial ECMOs were placed in the coronary angiography laboratory, whereas venovenous ECMOs were preferentially placed in the medical intensive care unit. Twenty patients (51.3%) were medically transferred to other referral centres after canulation. Percutaneous vascular cannulation was performed with ultrasound guidance in all cases (100%), and was successfully performed without immediate complications in all patients except two (who presented an immediate complication during cannulation), which is similar to large trials, despite the absence of on-site cardiac surgery. The use of ultrasound guidance (and sometimes fluoroscopy guidance) during cannulation and the experience of the medical team facilitated control over correct positioning of the cannulas and decreased implantation failure, without the need for a surgical approach. Percutaneous ECMO by trained interventional cardiologists without a surgical approach appears to be safe. Widespread use of percutaneous cannulation without cardiac surgery would increase survival for some patients who are far from these centres.

Study on improving heat extraction capacity of borehole heat exchanger by forced convection of groundwater

Borehole Heat Exchangers (BHEs) has the advantage of "extracting heat without extracting groundwater". Its main drawback is low heat extraction power. Aiming at developing medium-deep hydrothermal geothermal resources, a Branch Well Reinforced Coaxial Borehole Heat Exchanger (BWR-CBHE) is proposed firstly. An assisted circulation loop formed by the wellbore and geothermal reservoir is created through drilling branch well and installing electric submersible pump (ESP). By driving the forced convection of groundwater within the assisted circulation loop, heat extraction capacity of the CBHE is enhanced. Then, a numerical model of the BWR-CBHE is established. The main circulation of the working fluid within the CBHE is coupled with the assisted circulation of groundwater, and the heat extraction performance of the BWR-CBHE is calculated. Under the conditions studied in this paper, the net heat extraction power (after deducting the energy consumption of the ESP) of the BWR-CBHE is 6.09 times higher than that of conventional CBHEs. Finally, impacts of parameters, including working fluid, branch well, ESP and formation, on the heat extraction capacity of the BWR-CBHE are discussed. The heat extraction power of the BWR-CBHE is increased significantly without extracting groundwater, which provides a new approach for the development of BHEs.

Series Multiblood Pump Design With Dual Activation for Pediatric Patients With Heart Failure.

The translational development of pediatric ventricular assist devices (VADs) lags years behind adult device options, negatively impacting pediatric patient outcomes. To address this need, we are developing a novel, series-flow, double-blood pump VAD that integrates an axial and centrifugal pump into a single device. The axial pump is used for initial circulatory assistance in younger patients; then, an internal activation mechanism triggers the centrifugal pump to activate in line with the axial pump, providing additional pressure and flow to match pediatric patient growth cycles. Here, we focused on the design and improvement of the device flow paths through computational analysis and in vitro hydraulic testing of a prototype. We estimated pressure-flow generation, fluid scalar stresses, and blood damage levels. In vitro hydraulic tests correlated well with shear stress transport (SST) predictions, with an average deviation of 4.5% for the complex, combined flow path. All data followed expected pump performance trends. The device exceeded target levels for blood damage in the blade tip clearances, and this must be both investigated and addressed in the next design phase. These study findings establish a strong foundation for the future development of the Drexel Double-Dragon VAD.

Extracorporeal membrane oxygenation states basilar artery thrombectomy and left posterior cerebral artery stent thrombectomy: A case report

BACKGROUND Extracorporeal membrane oxygenation (ECMO) is a new type of extracorporeal respiratory and circulatory assistance device. It can drain venous blood out of the body and inject it into veins or arteries after being oxygenated by an oxygenator (membrane lung) to replace lung and heart functions in a short time. ECMO can provide tissue blood perfusion and gas exchange almost equivalent to cardiac output and extend the effective treatment time window for patients with acute circulatory failure to restore cardiopulmonary function. CASE SUMMARY We report a case of an 81-year-old woman who underwent whole cerebral angiography, basilar artery thrombectomy and stent thrombectomy in the posterior artery of the left brain after implantation of ECMO. The patient was admitted to the hospital due to myocardial infarction. Considering that the cause of the patient’s disturbance of consciousness was unknown and cerebrovascular accident could not be ruled out after the implantation of ECMO, the department of Radioactive Intervention performed cerebral angiography. And the result of the angiography indicated vascular occlusion. After the basilar artery thrombectomy and stent thrombectomy in the posterior artery of the left brain, the patency of the occlusive vessel was achieved. CONCLUSION Although the patient eventually died of circulatory failure, the result of this case verifies the feasibility of cerebral angiography and thrombectomy in patients with implanted ECMO in the intubated state.

The influence of the disk pump of assisted circulation of the left ventricular bypass on hemolytic blood parameters

The influence of the disk pump of assisted circulation of the left ventricular bypass on hemolytic blood parameters

Enhanced external counterpulsation treatment improves multi-organ hemodynamics for postoperative liver transplantation patient. A case report

IntroductionPost liver transplantation (LT) patients endure high morbidity rate of multi-organ ischemic symptoms following reperfusion. We hypothesize that enhanced external counterpulsation (EECP) as a typical non-invasive assisted circulation procedure, which can efficiently inhibit the relative ischemic symptoms via the systemic improvement of hemodynamics.Case presentationA 51-year-old male patient, 76 kg, 172 cm, received orthotopic LT surgery for viral hepatitis B induced acute-on-chronic liver failure hepatic failure. His medical records revealed ischemic symptoms in multi-organ at the time of hospital discharge, including headache, refractory insomnia, abdominal paralysis, and lower limb pain. The EECP treatment was introduced for assisted rehabilitation and to improve the postoperative quality of life. Doppler Ultrasound examination showed significant augmentation of blood flow volume in the carotid arteries, the hepatic artery, the portal vein and the femoral artery during EECP intervention. A standard 35-hour EECP treatment led to significant improvement in quality of life, e.g. sleep quality and walking ability.ConclusionWe report a case of multi-organ ischemic symptoms in a post LT patient. EECP treatment can significantly improve the quality of life via the systematic promotion of hemodynamics.

Study on the optimal elastic modulus of flexible blades for right heart assist device supporting patients with single-ventricle physiologies.

Patients with single-ventricle physiologies continue to experience insufficient circulatory power after undergoing palliative surgeries. This paper proposed a right heart assist device equipped with flexible blades to provide circulatory assistance for these patients. The optimal elastic modulus of the flexible blades was investigated through numerical simulation. A one-way fluid-structure interaction (FSI) simulation was employed to study the deformation of flexible blades during rotation and its impact on device performance. The process began with a computational fluid dynamics (CFD) simulation to calculate the blood pressure rise and the pressure on the blades' surface. Subsequently, these pressure data were exported for finite element analysis (FEA) to compute the deformation of the blades. The fluid domain was then recreated based on the deformed blades' shape. Iterative CFD and FEA simulations were performed until both the blood pressure rise and the blades' shape stabilized. The blood pressure rise, hemolysis risk, and thrombosis risk corresponding to blades with different elastic moduli were exhaustively evaluated to determine the optimal elastic modulus. Except for the case at 8,000 rpm with a blade elastic modulus of 40 MPa, the pressure rise associated with flexible blades within the studied range (rotational speeds of 4,000 rpm and 8,000 rpm, elastic modulus between 10 MPa and 200 MPa) was lower than that of rigid blades. It was observed that the pressure rise corresponding to flexible blades increased as the elastic modulus increased. Additionally, no significant difference was found in the hemolysis risk and thrombus risk between flexible blades of various elastic moduli and rigid blades. Except for one specific case, deformation of the flexible blades within the studied range led to a decrease in the impeller's functionality. Notably, rotational speed had a more significant impact on hemolysis risk and thrombus risk compared to blade deformation. After a comprehensive analysis of blade compressibility, blood pressure rise, hemolysis risk, and thrombus risk, the optimal elastic modulus for the flexible blades was determined to be between 40 MPa and 50 MPa.

Predictors of low cardiac output syndrome after combined mitral and tricuspid valve surgery.

Low cardiac output syndrome (LCOS) is a common complication in cardiac surgery, and we evaluated the incidence of its early occurrence after mitral and tricuspid combined cardiac surgery and its associated risk factors. Retrospective, single institution study. We included 88 consecutive adult patients with severe mitral insufficiency scheduled for elective mitral and tricuspid valve replacement surgery between January 2015 and November 2018. The primary endpoint was the occurrence of LCOS, defined as the need for inotropic support or circulatory assistance after surgery. The secondary endpoint was mortality at 30 days. LCOS occurred in 26 patients (29.5%) of the studied patients and its associated risk factors that appeared in the multivariate analysis were chronic kidney failure [adjusted odds ratio (OR) 3.1; 95% confidence interval (CI) 1.0-9.9, p = 0.05], pre-operative left ventricular heart failure (OR 5.3; 95% CI 1.3-10.9, p = 0.002), pre-operative right ventricular heart failure (OR 3.6; 95% CI 1.1-11.5, p = 0.02), and mitral valve replacement (OR 3.9; 95% CI 1.2-12.6, p = 0.03). LCOS affected the survival of patients (HR = 5.5; 95% CI 1.1-27.7 p = 0.04). LCOS is a frequent complication after mitral and tricuspid combined surgery and is associated with poor prognosis.

Relationship Between Regional Cerebral Oxygen Saturation and Percutaneous Oxygen Saturation at Initial Mobilisation in Patients with Acute Heart Failure.

In patients with acute heart failure, early mobilisation is performed according to physical condition, biometric information, and haemodynamic stability. Regional cerebral oxygen saturation (rSO2) is useful in monitoring patients during assisted circulation and cardiac arrest, but the measurement of rSO2 during early mobilisation is not standardised, and its relationship with percutaneous oxygen saturation (SpO2) has not been investigated. This study aimed to investigate the relationship between rSO2 and SpO2 during initial mobilisation in patients with acute heart failure. Patients with acute heart failure who presented to our emergency centre and were referred for physical therapy were included in this study. Data from 21 of the 24 patients who decided to start mobilisation based on the criteria of the Japanese Society of Intensive Care Medicine were analysed. The resting rSO2 was 58.6%, and it significantly changed (p<0.001), with a decrease in the first half of sitting on the edge of the bed (SEB) and an increase from the second half to the end of the SEB. The resting SpO2 was 96.0%, with a trend towards an increase in the latter half of the SEB (p=0.05608). Changes in rSO2 during initial mobilisation in patients with acute heart failure differed from those in SpO2.

Cardiac intensive care unit: where we are in 2023

Cardiac intensive care has been a constantly evolving area of research and innovation since the beginning of the 21st century. The story began in 1961 with Desmond Julian's pioneering creation of a coronary intensive care unit to improve the prognosis of patients with myocardial infarction, considered the major cause of death in the world. These units have continued to progress over time, with the introduction of new therapeutic means such as fibrinolysis, invasive hemodynamic monitoring using the Swan-Ganz catheter, and mechanical circulatory assistance, with significant advances in percutaneous interventional coronary and structural procedures. Since acute cardiovascular disease is not limited to the management of acute coronary syndromes and includes other emergencies such as severe arrhythmias, acute heart failure, cardiogenic shock, high-risk pulmonary embolism, severe conduction disorders, and post-implantation monitoring of percutaneous valves, as well as other non-cardiac emergencies, such as septic shock, severe respiratory failure, severe renal failure and the management of cardiac arrest after resuscitation, the conversion of coronary intensive care units into cardiac intensive care units represented an important priority. Today, the cardiac intensive care units (CICU) concept is widely adopted by most healthcare systems, whatever the country's level of development. The main aim of these units remains to improve the overall morbidity and mortality of acute cardiovascular diseases, but also to manage other non-cardiac disorders, such as sepsis and respiratory failure. This diversity of tasks and responsibilities has enabled us to classify these CICUs according to several levels, depending on a variety of parameters, principally the level of care delivered, the staff assigned, the equipment and technologies available, the type of research projects carried out, and the type of connections and networking developed. The European Society of Cardiology (ESC) and the American College of Cardiology (ACC) have detailed this organization in guidelines published initially in 2005 and updated in 2018, with the aim of harmonizing the structure, organization, and care offered by the various CICUs. In this state-of-the-art report, we review the history of the CICUs from the creation of the very first unit in 1968 to the discussion of their current perspectives, with the main objective of knowing what the CICUs will have become by 2023.

Lipid Emulsion for Spinal Anaesthesia Reversal - A Therapeutic Option

High spinal anaesthesia is also one of the commonly faced problems, with a low incidence of a complete spinal block; which is one of the life-threatening complications unless immediately identified and treated. Up to now, its management has relied mainly on intensive means such as respiratory and circulatory assistance. Intravenous lipid emulsions have an established position in the management of local anesthetic toxicity. After the success in this area, ILE has been used under clinical conditions for various kinds of overdose. At present, ILEs are expanding into a new field, that of reversing the effects of local anesthesia on peripheral nerves and neuraxial anesthesia. We report two cases of patients operated at our department, the first for genital prolapse under perimedullary anaesthesia, complicated by high spinal anaesthesia. The second case was a patient who underwent Caesarean section under spinal anaesthesia, intubated mid-operatively and presented with postoperative delayed awakening. Both complications were resolved by intralipid injection. We then reviewed the literature concerning similar cases and the different means used to resolve the problem.

Anatomical Correction of Transposition of the Great Arteries at the Arterial Level with Dacron Patch Closure of Multiple Ventricular Septal Defects under Integrated Extracorporeal Membrane Oxygenation: A Video Presentation

A 5-week-old male child, weighing 4 kg diagnosed with d-transposition of the great arteries with multiple muscular ventricular septal defects, Yacoub’s type-A coronary arterial pattern, successfully underwent arterial switch operation with Dacron patch closure of ventricular septal defects under moderately hypothermic cardiopulmonary bypass and St. Thomas based cold blood cardioplegia under integrated extracorporeal membrane oxygenation. Postoperatively, he required mechanical circulatory assistance for 72 h. At 12 months of follow-up, there was no mitral or tricuspid regurgitation, no neoaortic valve insufficiency with good biventricular function in Ross clinical score of 2.

Enhanced external counterpulsation treatment regulates blood flow and wall shear stress metrics in femoral artery: An in vivo study in healthy subjects

As a non-invasive assisted circulation therapy, enhanced external counterpulsation (EECP) has demonstrated potential in treatment of lower-extremity arterial disease (LEAD). However, the underlying hemodynamic mechanism remains unclear. This study aimed to conduct the first prospective investigation of the EECP-induced responses of blood flow behavior and wall shear stress (WSS) metrics in the femoral artery. Twelve healthy male volunteers were enrolled. A Doppler ultrasound-basedapproach was introduced for the in vivo determination of blood flow in the common femoral artery (CFA) and superficial femoral artery (SFA) during EECP intervention, with incremental treatment pressures ranging from 10 to 40 kPa. Three-dimensional subject-specific numerical models were developed in 6 subjects to quantitatively assess variations in WSS-derived hemodynamic metrics in the femoral bifurcation. A mesh-independence analysis was performed. Our results indicated that, compared to the pre-EECP condition, both the antegrade and retrograde blood flow volumes in the CFA and SFA were significantly augmented during EECP intervention, while the heart rate remained constant. The time average shear stress (TAWSS) over the entire femoral bifurcation increased by 32.41%, 121.30%, 178.24%, and 214.81% during EECP with treatment pressures of 10 kPa, 20 kPa, 30 kPa, and 40 kPa, respectively. The mean relative resident time (RRT) decreased by 24.53%, 61.01%, 69.81%, and 77.99%, respectively. The percentage of area with low TAWSS in the femoral artery dropped to nearly zero during EECP with a treatment pressure greater than or equal to 30 kPa. We suggest that EECP is an effective and non-invasive approach for regulating blood flow and WSS in lower extremity arteries.

Normothermic &lt;i&gt;ex vivo&lt;/i&gt; lung perfusion using a developed solution followed by orthotopic left lung transplantation (experimental study)

The continued unavailability of adequate organs for transplantation to meet the existing demand has resulted in a major challenge in transplantology. This is especially felt in lung transplantation (LTx). LTx is the only effective method of treatment for patients with end-stage lung diseases. Normothermic ex vivo lung perfusion (EVLP) has been proposed to increase the number of donor organs suitable for transplant – EVLP has proven itself in a number of clinical trials. The ability to restore suboptimal donor lungs, previously considered unsuitable for transplantation, can improve organ functionality, and thus increase the number of lung transplants. However, widespread implementation of ex vivo perfusion is associated with high financial costs for consumables and perfusate.Objective: to test the developed solution on an ex vivo lung perfusion model, followed by orthotopic LT under experimental conditions.Materials and methods. The experiment included lung explantation stages, static hypothermic storage, EVLP and orthotopic left LTx. Perfusion was performed in a closed perfusion system. We used our own made human albumin-based perfusion solution as perfusate. Perfusion lasted for 2 hours, and evaluation was carried out every 30 minutes. In all cases, static hypothermic storage after perfusion lasted for 4 hours. The orthotopic single-lung transplantation procedure was performed using assisted circulation, supplemented by membrane oxygenation. Postoperative follow-up was 2 hours, after which the experimental animal was euthanized.Results. Respiratory index before lung explantation was 310 ± 40 mmHg. The PaO2/FiO2 ratio had positive growth dynamics throughout the entire EVLP procedure. Oxygenation index was 437 ± 25 mm Hg after 120 minutes of perfusion. Throughout the entire EVLP procedure, there was a steady decrease in pulmonary vascular resistance (PVR). Initial PVR was 300 ± 100 dyn×s/cm5; throughout the EVLP, PVR tended to fall, reaching 38,5 ± 12 dyn×s/cm5 at the end of perfusion.Conclusion. A safe and effective EVLP using our perfusate is possible. The developed orthotopic left lung transplantation protocol under circulatory support conditions, supplemented by membrane oxygenation, showed it is efficient and reliable.

A study on the immediate effects of enhanced external counterpulsation on physiological coupling.

Enhanced external counterpulsation (EECP) is a non-invasive assisted circulation technique for its clinical application in the rehabilitation and management of ischemic cardiovascular and cerebrovascular diseases, which has complex physiological and hemodynamic effects. However, the effects of EECP on the coupling of physiological systems are still unclear. We aimed to investigate the immediate effects of EECP on the coupling between integrated physiological systems such as cardiorespiratory and cardiovascular systems. Based on a random sham-controlled design, simultaneous electrocardiography, photoplethysmography, bio-electrical impedance, and continuous hemodynamic data were recorded before, during and after two consecutive 30 min EECP in 41 healthy adults. Physiological coupling strength quantified by phase synchronization indexes (PSI), hemodynamic measurements and heart rate variability indices of 22 subjects (female/male: 10/12; age: 22.6 ± 2.1 years) receiving active EECP were calculated and compared with those of 19 sham control subjects (female/male: 7/12; age: 23.6 ± 2.5 years). Immediately after the two consecutive EECP interventions, the physiological coupling between respiratory and cardiovascular systems PSIRES-PTT (0.34 ± 0.14 vs. 0.49 ± 0.17, P = 0.002), the physiological coupling between cardiac and cardiovascular systems PSIIBI-PTT (0.41 ± 0.14 vs. 0.52 ± 0.16, P = 0.006) and the total physiological coupling PSItotal (1.21 ± 0.35 vs. 1.57 ± 0.49, P = 0.005) in the EECP group were significantly lower than those before the EECP intervention, while the physiological coupling indexes in the control group did not change significantly (P > 0.05). Our study provides evidence that the PSI is altered by immediate EECP intervention. We speculate that the reduced PSI induced by EECP may be a marker of disturbed physiological coupling. This study provides a new method for exploring the mechanism of EECP action and may help to further optimize the EECP technique.

P52: ECMO Circuit Exchange on a Single Pump Console: Maximizing Mechanical Circulatory Support Resources in the High Census Pediatric Environment

Background: Pediatric hospitals have faced an unprecedented period of high census due to a confluence of respiratory illnesses, resulting in increased use of ECMO for rescue and long-term therapy. Combined with equipment demands imposed by a cardiac surgical program, ECMO disposables and pump console inventories have been stretched to their limits in many centers. Circuit exchanges place additional burden on device numbers, as two pump consoles are typically used for the changeout procedure. We report the case of an infant cardiac surgical patient requiring ECMO circuit exchange while the remainder of appropriately sized systems were in use on other patients in the hospital. Methods: A 3kg infant with complex congenital heart disease on VA ECMO post repair required circuit exchange due to consumptive coagulopathy and significantly increased trans-oxygenator gradient after multiple weeks of support. Due to a concurrent period of high ECMO utilization, a size appropriate replacement system was unavailable. In our institution, cardiac patients under 20kg requiring mechanical circulatory assistance are supported on a roller system with multiple pump heads, allowing conversion from ECMO to cardiopulmonary bypass without exposing the patient to an additional circuit and associated sequalae. After careful planning, the decision was made to build and prime a replacement circuit on the currently used pump base, using one of the accessory roller heads to de-air and recirculate the system. The pump-mounted oxygen tank was used to oxygenate the blood-primed circuit, and an extra heater was used to bring the perfusate up patient temperature. Three-way stopcocks placed on the venous, pre-, and post-oxygenator transducers allowed simultaneous pressure monitoring of both circuits. After a period of recirculation, the new infusion and return lines were handed up to the field and marked with white tape to denote new versus old tubing. A brief period off support was well tolerated as the circuits were changed out at the arterial and venous cannula connections, and subsequently the old circuit was removed from the pump base and discarded. Sweep control was re-established by the on-board mixer and flow meters, and water lines were reconnected to the on-board heater.

“Double Myocardial Infarct Syndrome” resulting from Simultaneous Occlusion of Dual Coronary Arteries: A Double Jeopardy

Angiographic evidence of thrombosis in more than one coronary artery at the same time is uncommon in patients with acute myocardial infarction, and this is hard to identify with routine electrocardiography. Patients may manifest with high-degree atrioventricular block, cardiogenic shock, or sudden cardiac arrest, all of which are potentially fatal outcomes. This case study focuses on a patient who experienced cardiogenic shock, high-degree atrioventricular block secondary to acute anterior-inferior ST-segment elevation myocardial infarction. During the coronary angiogram, thrombotic occlusions of the left anterior descending and right coronary arteries were observed. A patient was salvaged by the use of mechanical circulatory assistance in conjunction with prompt percutaneous coronary intervention of both the culprit arteries. Our case report emphasizes the importance of completing revascularization as soon as possible by opening the culprit arteries and ensuring appropriate mechanical circulatory support to the patient.

BIO30: A Method to Monitor Ventricular Recovery Using VAD Signals Based on Parseval’s Power Theorem

Study: Recent studies highlight the growing interest in achieving ventricular recovery for VAD patients, thereby eliminating the need for cardiac transplantation. Hemodynamic measurements may be performed during periodic echocardiography for patients with probable recovery. However, there are no standard methods to evaluate ventricular recovery on a continuous outpatient basis. Such a method can help assess changes in cardiac function throughout daily activities, potentially optimized by a responsive VAD control algorithm. The objective of this study was to evaluate a surrogate measure of cardiac contractility based on VAD inherent signals using an in-silico simulation model of assisted circulation. Methods: Without loss of generality, hemodynamic power can be visualized as an electrical power signal in an implanted VAD. The power of a continuous periodic signal (the VAD Flow Rate signal), given by Parseval’s Power Theorem, is equivalently the average value integral over one period of the square of the magnitude of the signal (inclusive of all harmonic components). In this in-silico simulation study, we compute the ratio of this power with the norm (over multiple cardiac cycles) of the signal under steady-state conditions. We call this ratio the Power Factor of the VAD Flow Rate, represented by λVAD. Numerical simulations were conducted for different values of ventricular contractility (Emax Maximum Ventricular Elastance) from 0.5 to 2.0 mmHg/ml over a range of VAD speeds of 1000 to 8000 RPM (HeartMate 3® VAD Model) in steps of 100 RPM. Results: The figure below illustrates the relationship of the Power Factor to VAD speed for four levels of ventricular contractility. At 1000 RPM, the Power Factor for all Emax values was found to be equal. As the VAD speed increases above approximately 4000 RPM, the λVAD values diverge, demonstrating the direct relationship with Emax: having a peak of approximately 0.8 for the greatest ventricular contractility (Emax = 2.0). As speed increases further and approaches 8000 RPM, the values of λVAD once again converge. Another discriminating feature is the location (speed) of the local maximum (“hump”) in the curves within the range of 4000 and 6000 RPM, with the peak occurring at increasing speeds for increasing contractility. The cause of the hump is due to the cooperative relationship of the VAD and native ventricle, precisely the point of the aortic valve opening, allowing forward flow. At the lowest speeds, there is a slight negative flow through the VAD and, thus, a more subdued λVAD. Conclusion: This simulation study shows that the Power Factor of VAD flow rate has the potential as a noninvasive surrogate measure of ventricular recovery that can be monitored continuously. The metric is sensitive to the interaction between the native left ventricle and the VAD and thus helpful in developing feedback control that optimizes cardiac rehabilitation.Figure 1. Simulation results for the Power Factor of VAD Flow Rate as a function of different VAD Speeds (RPM).

Clinical relevance and prognostic value of renal Doppler in acute decompensated precapillary pulmonary hypertension.

We aim to evaluate the clinical relevance and the prognostic value of arterial and venous renal Doppler in acute decompensated precapillary pulmonary hypertension (PH). The renal resistance index (RRI) and the Doppler-derived renal venous stasis index (RVSI) were monitored at admission and on Day 3 in a prospective cohort of precapillary PH patients managed in intensive care unit for acute right heart failure (RHF). The primary composite endpoint included death, circulatory assistance, urgent transplantation, or rehospitalization for acute RHF within 90 days following inclusion. Ninety-one patients were enrolled (58% female, age 58 ± 16 years). The primary endpoint event occurred in 32 patients (33%). In univariate logistic regression analysis, variables associated with RRI higher than the median value were non-variable parameters (age and history of hypertension), congestion (right atrial pressure and renal pulse pressure), cardiac function [tricuspid annular plane systolic excursion (TAPSE) and left ventricular outflow tract- velocity time integral], systemic pressures and NT-proBNP. Variables associated with RVSI higher than the median value were congestion (high central venous pressure, right atrial pressure, and renal pulse pressure), right cardiac function (TAPSE), severe tricuspid regurgitation, and systemic pressures. Inotropic support was more frequently required in patients with high RRI (P = 0.01) or high RVSI (P = 0.003) at the time of admission. At Day 3, a RRI value <0.9 was associated with a better prognosis after adjusting to the estimated glomerular filtration rate. Renal Doppler provides additional information to assess the severity of patients admitted to the intensive care unit for acute decompensated precapillary PH.

Mechanical Circulatory Assistance in Children: Clinical Outcome

In countries where organ donation is scarce, mortality in the pediatric heart transplant waiting list is high, and ventricular assist devices (VADs) are therapeutic alternatives in these situations. Berlin Heart EXCOR is currently 1 of the few VADs specific for children. This retrospective study includes pediatric patients who underwent Berlin Heart EXCOR placement in a Brazilian hospital between 2012 and 2021. Clinical and laboratory data at the time of VAD implantation and the occurrence of complications and outcomes (success as a bridge to transplant or death) were analyzed. Eight patients, from 8 months to 15 years, were included: 6 with cardiomyopathy and 2 with congenital heart disease. Six were on Intermacs 1 and 2 on Intermacs 2. The most common complications observed were stroke and right ventricular dysfunction. Six were transplanted, and 2 died. Those submitted to transplant had a higher mean weight than those who died, with no statistically significant difference. The underlying disease had no impact on the outcome. The group undergoing transplant had lower brain natriuretic peptide and lactate values, but no laboratory variable showed a statistically significant difference in the outcome. A VAD is an invasive treatment with potentially serious adverse effects and is still poorly available in Brazil. However, as a bridge to transplant, it is a useful treatment for children in progressive clinical decline. In this study, we did not observe any clinical or laboratory factor at the time of VAD implantation that implied better outcomes.