Extracorporeal membrane oxygenation versus counterpulsatile, pulsatile, and continuous left ventricular unloading for pediatric mechanical circulatory support

Steady Flow Left Ventricle Unloading Is Superior to Pulsatile Pressure Augmentation Venting During Venoarterial Extracorporeal Membrane Oxygenation Support

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) shunts venous blood to the systemic arterial circulation to provide end-organ perfusion while increasing afterload that may impede left ventricle (LV) ejection and impair cardiac recovery. To maintain flow across the aortic valve and reduce risk of lethal clot formation, secondary mechanical circulatory support (MCS) devices are increasingly used despite limited understanding of their effects on cardiac function. This study sought to quantify the effects of VA-ECMO and combined with either intraaortic balloon pump (IABP) or percutaneous ventricular assist device (pVAD) on LV physiologic state and perfusion metrics in a porcine model of acute cardiogenic shock. Shock was induced through serial left anterior descending artery microbead embolization followed by initiation of VA-ECMO support and then placement of either IABP or pVAD. Hemodynamic measurements, LV pressure-volume loops, and carotid artery blood flow were evaluated before and after institution of combined MCS. The IABP decreased LV end-diastolic pressure by a peak of 15% while slightly increasing LV stroke work compared with decreases of more than 60% and 50% with the pVAD, respectively. The pVAD also demonstrated increased coronary perfusion and systemic pressure gradients in comparison to the IABP. Combined support with VA-ECMO and pVAD improves cardiovascular state in comparison to IABP.

Survival Outcome in Critically Ill Patients Receiving Extracorporeal Membrane Oxygenation Support: Early Experience from a University Hospital in Thailand

Objective  Extracorporeal membrane oxygenation (ECMO) is a relatively new technology used for life support in patients with cardiopulmonary failure from various causes. The objective of this study is to review the first 5-year experience in adopting this technology in a teaching hospital in southern Thailand. Methods  The data of ECMO-supported patients in Songklanagarind Hospital, from the years 2014 to 2018, were retrospectively reviewed. Data sources were from electronic medical records and the database of the perfusion service. Parameters in focus included prior conditions and indications of ECMO, type of ECMO and cannulation method, complications during and after the treatment, and discharge statuses. Results  A total of 83 patients received ECMO life support during the 5-year period and the number of cases per year increased. The proportion of venovenous: venoarterial ECMO in our institute was 49:34 cases and there were three cases who used ECMO as a part of cardiopulmonary resuscitation. Moreover, there were 57 cases who used ECMO for cardiac failure and 26 cases were for respiratory causes, while premature withdrawal was decided in 26 cases (31.3%). Overall survival from ECMO was 35/83 cases (42.2%) and survival to discharge was 32/83 (38.6%). During therapy, ECMO could restore serum pH to the normal range in all cases. Furthermore, those who used ECMO for respiratory failure had significantly higher survival probability (57.7%) when compared to the cardiac counterpart (29.8%, p -value = 0.03). Patients with younger ages also had significantly better survival outcomes. The most common complications were cardiac (75 cases, 85.5%), followed by renal (45 cases, 54.2%), and hematologic systems (38 cases, 45.8%). In those who survived to discharge, average ECMO duration was 9.7 days. Conclusion  Extracorporeal life support is a technology that bridges the patients with cardiopulmonary failure to their recovery or definitive surgery. Despite the high complication rate, survival can be expected, especially in respiratory failure cases and relatively young patients.

Clinical Implications for Children Developing Direct Hyperbilirubinemia on Extracorporeal Membrane Oxygenation

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO)-associated direct hyperbilirubinemia (DHB) is likely multifactorial. The objective of this study is to assess the frequency and risk factors for developing direct hyperbilirubinemia while on ECMO, and its implication on the mortality of children.

METHODS

We performed a retrospective study between January 2010 and January 2020. Using Mayo Clinic electronic health record, we identified children (<18 years) who required veno-arterial (VA) ECMO support. Demographics, ECMO indication, laboratory findings, and outcomes were abstracted. Illness acuity scores, including vasoactive-ionotropic score (VIS), were used to assess disease severity at time of admission. Study cohort was divided into two groups: children who developed direct hyperbilirubinemia (DHB) on ECMO and children who did not (control). DHB was defined as direct bilirubin (DB) of >1.0 mg/dL. Disease acuity and mortality rates were compared between the two groups. Logistic regression was used to analyze the risk of mortality independent of potential confounding variables.

RESULTS

We identified 106 children who required ECMO support during the study period. Of those, 36 (34%) children developed DHB on ECMO. Illness acuity scores were significantly higher in the DHB group on ECMO day 2 (P = 0.046) and day 7 (P = 0.01). Mortality rate was higher in the DHB group 72%, versus 29% in the control group (P < 0.001).

CONCLUSION

DHB was associated with a higher mortality rate than the control group.

An innovative ovine model of severe cardiopulmonary failure supported by veno-arterial extracorporeal membrane oxygenation

Refractory cardiogenic shock (CS) often requires veno-arterial extracorporeal membrane oxygenation (VA-ECMO) to sustain end-organ perfusion. Current animal models result in heterogenous cardiac injury and frequent episodes of refractory ventricular fibrillation. Thus, we aimed to develop an innovative, clinically relevant, and titratable model of severe cardiopulmonary failure. Six sheep (60 ± 6 kg) were anaesthetized and mechanically ventilated. VA-ECMO was commenced and CS was induced through intramyocardial injections of ethanol. Then, hypoxemic/hypercapnic pulmonary failure was achieved, through substantial decrease in ventilatory support. Echocardiography was used to compute left ventricular fractional area change (LVFAC) and cardiac Troponin I (cTnI) was quantified. After 5 h, the animals were euthanised and the heart was retrieved for histological evaluations. Ethanol (58 ± 23 mL) successfully induced CS in all animals. cTnI levels increased near 5000-fold. CS was confirmed by a drop in systolic blood pressure to 67 ± 14 mmHg, while lactate increased to 4.7 ± 0.9 mmol/L and LVFAC decreased to 16 ± 7%. Myocardial samples corroborated extensive cellular necrosis and inflammatory infiltrates. In conclusion, we present an innovative ovine model of severe cardiopulmonary failure in animals on VA-ECMO. This model could be essential to further characterize CS and develop future treatments.

Pediatric ventricular assist device registries: update and perspectives in the era of miniaturized continuous-flow pumps

The success of ventricular assist devices (VADs) in the treatment of end-stage heart failure in the adult population has led to industrial innovation in VAD design, focusing on miniaturization and the reduction of complications. A byproduct of these innovations was that newer generation devices could have clinical applications in the pediatric population. Over the last decade, VAD usage in the pediatric population has increased dramatically, and the newer generation continuous flow (CF) devices have begun to supplant the older, pulsatile flow (PF) devices, formerly the sole option for ventricular assist in the pediatric population. However, despite the increase in VAD implants in the pediatric population, patient numbers remain low, and the need to share data between pediatric VAD centers has become that much more important for the continued growth of VAD programs worldwide. The creation of pediatric VAD registries, such as the Pediatric Registry for Mechanical Circulatory Support (PediMACS), the European Registry for Patients with Mechanical Circulatory Support (EUROMACS) and the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has enabled the collection of aggregate data from VAD centers worldwide, and provides a valuable resource for clinicians and programs, as more and more pediatric heart failure patients are considered candidates for VAD therapy.

Heart failure supported by veno-arterial extracorporeal membrane oxygenation (ECMO): a systematic review of pre-clinical models

OBJECTIVES

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly being used to treat patients with refractory severe heart failure. Large animal models are developed to help understand physiology and build translational research projects. In order to better understand those experimental models, we conducted a systematic literature review of animal models combining heart failure and VA-ECMO.

STUDIES SELECTION

A systematic review was performed using Medline via PubMed, EMBASE, and Web of Science, from January 1996 to January 2019. Animal models combining experimental acute heart failure and ECMO were included. Clinical studies, abstracts, and studies not employing VA-ECMO were excluded.

DATA EXTRACTION

Following variables were extracted, relating to four key features: (1) study design, (2) animals and their peri-experimental care, (3) heart failure models and characteristics, and (4) ECMO characteristics and management.

RESULTS

Nineteen models of heart failure and VA-ECMO were included in this review. All were performed in large animals, the majority (n = 13) in pigs. Acute myocardial infarction (n = 11) with left anterior descending coronary ligation (n = 9) was the commonest mean of inducing heart failure. Most models employed peripheral VA-ECMO (n = 14) with limited reporting.

CONCLUSION

Among models that combined severe heart failure and VA-ECMO, there is a large heterogeneity in both design and reporting, as well as methods employed for heart failure. There is a need for standardization of reporting and minimum dataset to ensure translational research achieve high-quality standards.

Insufficient left ventricular unloading after extracorporeal membrane oxygenation : A case-series observational study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a method widely used to support circulation in patients with fulminant myocarditis (FM). However, a common complication associated with ECMO is left ventricular (LV) overload.

METHODS

This case series observed the effects of intra-aortic balloon pump (IABP) and beta-blockers for the treatment of LV overload after ECMO. The cases of eight patients with FM who underwent ECMO from September 2009 to July 2016 were reviewed.

RESULTS

Six of the eight patients survived. After ECMO treatment, insufficient LV unloading occurred in six patients. Among these six patients, three experienced electrical storm but spontaneous circulation returned after interventions with beta-blockers and IABP. The survivors demonstrated full recovery of cardiac function.

CONCLUSION

Beta-blockers may prevent the occurrence of electrical storm, and IABP is feasible for the treatment of LV overload after ECMO application.