The Introduction of an MR-Conditional Prototype for Cardiopulmonary Bypass Support: Technical Aspects and System Requirements.

INTRODUCTION: The use of cardiopulmonary bypass (CBP; also known as a heart-lung machine) in newborns with complex congenital heart defects may result in brain damage. Magnetic resonance imaging (MRI) assessments cannot be performed safely because the metal components used to construct CBP devices may elicit adverse effects on patients when they are placed in a magnetic field. Thus, this project aimed to develop a prototype MR-conditional circulatory support system that could be used to perform cerebral perfusion studies in animal models. METHODS: The circulatory support device includes a roller pump with two rollers. The ferromagnetic and most of the metal components of the roller pump were modified or replaced, and the drive was exchanged by an air-pressure motor. All materials used to develop the prototype device were tested in the magnetic field according to the American Society for Testing and Materials (ASTM) Standard F2503-13. The technical performance parameters, including runtime/durability as well as achievable speed and pulsation behavior, were evaluated and compared to standard requirements. The behavior of the prototype device was compared with a commercially available pump. RESULTS: The MRI-conditional pump system produced no image artifacts and could be safely operated in the presence of the magnetic field. The system exhibited minor performance-related differences when compared to a standard CPB pump; feature testing revealed that the prototype meets the requirements (i.e., operability, controllability, and flow range) needed to proceed with the planned animal studies. CONCLUSION: This MR-conditional prototype is suitable to perform an open-heart surgery in an animal model to assess brain perfusion in an MR environment.

Experience with a "hotline" service for outpatients on a ventricular assist device.

OBJECTIVES: With the growing number of outpatients on ventricular assist devices (VADs), there is an increasing need for "home discharge programs." One important feature is a 24-hour telephone service. In our center, the perfusionists run a so-called "hotline" for all of our VAD patients. This study analyzes the hotline calls with regard to frequency, the reason for calling, and the type of action undertaken. PATIENTS AND METHODS: Over a period of 5 years, 16 (12 EXCOR and 4 INCOR; Berlin Heart, Berlin, Germany) of 33 VAD patients (48%) were discharged and instructed to use the "hotline" service. All the calls received by the perfusionists were reviewed. We classified the calls into three levels according to the severity of the problem: Level (L) 1 = assistance provided by the perfusionist alone; L2 = calls requiring discussion with the surgeon on duty and/or visit to the outpatient clinic ahead of time; and L3 = immediate action and/or admission to the hospital. RESULTS: Over a period of 2,890 outpatient days (7.9 years), a total of 26 calls were registered. There were 0.9 calls per 100 patient days and 1.6 calls per discharged patient. Out of the 26 calls, 14 calls (54%) were classified as L1, 8 (31%) as L2, and 4 (15%) as L3. The most frequent reasons for L1 or L2 calls were fibrin deposits in the EXCOR pump chamber (39%), followed by battery dysfunction (19%). L3 calls were related to dysfunction of the EXCOR driving units in three cases and to an EXCOR pump chamber disconnection, which the patient did not survive. CONCLUSIONS: The institution of a hotline is an essential component of a VAD outpatient program. It provides a certain level of safety for the patient, although a residual risk remains.

Extracorporeal membrane oxygenation: beneficial strategy for lung transplant recipients.

The role of extracorporeal membrane oxygenation (ECMO) as a therapeutic strategy has been very well documented for over a decade now with consistently positive remarks. The aim of the present study was analyzing the outcome of ECMO application in our lung transplant program, especially the feasibility and safety of our ECMO approach. Therefore, we retrospectively analyzed the data of 15 patients recipients requiring ECMO support. We analyzed clinical data, complications, and survival of the lung-transplanted population that needed ECMO support at our institution from 2006-2009. During that period, 19 applications of ECMO were done on 15 adult patients with the following indications: primary graft dysfunction (10 patients), "bridge to transplantation" (five), pulmonary hypertension (three), and severe acute respiratory distress syndrome (one). At 28 days, the overall survival was 93% (14 of 15 patients) and 12 of these patients (80%) survived at least 6 months. Complications included acute renal insufficiency with temporary need of renal replacement therapy (53%), bleeding (33%), critical illness polyneuropathy (66%), and reversible thrombocytopenia (73%). Based on the evaluation of the patients in this analysis, ECMO seems to be a safe therapeutic approach in lung transplant recipients with severe respiratory failure directly after transplantation.

Extracorporeal membrane oxygenation support in pediatrics.

Extracorporeal membrane oxygenation (ECMO) is a general term that describes the short- or long-term support of the heart and/or lungs in neonates, children and adults. Due to favorable results and a steady decline in absolute contraindications, its use is increasing worldwide. Indications in children differ from those in adults. The ECMO circuit as well as cannulation strategies also are individualized, considering their implications in children. The aim of this article is to review the clinical indications, different circuits, and cannulation strategies for ECMO. We also present our institutional experience with 92 pediatric ECMO patients (34 neonates, 58 pediatric) with the majority (80%) of veno-arterial placements between 2014 until 2018. We further to also highlight ECMO use in the setting of cardiac arrest [extracorporeal cardiopulmonary resuscitation (CPR) or eCPR].

Interhospital transfer of seriously sick ARDS patients using veno-venous Extracorporeal Membrane Oxygenation (ECMO): Concept of an ECMO transport team.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) therapy constitutes the last option for patients with acute respiratory distress syndrome (ARDS) refractory to conservative treatment. Since primary care centers are unable to provide this therapy, such patients need a transfer to a tertiary care center, which may be life-threatening without extracorporeal support. METHODS: An ECMO transport team implanted an ECMO at the site of the primary care center with subsequent transport of the patient to the tertiary care center. Between September 2009 and March 2011, six patients with ARDS were treated by our ECMO transport team. Mean age was 39.5±12.0 years. All implantations were done percutaneously in a veno-venous configuration. RESULTS: No complications occurred during the implant procedure and the subsequent transport. Four patients (67%) were successfully weaned from ECMO-therapy, and discharged from hospital. CONCLUSION: With a specialized ECMO transport team, ECMO-implantation can be achieved successfully in a peripheral hospital, and patients can be transported safely.

Thoraco-abdominal high-pitch dual-source CT angiography: experimental evaluation of injection protocols with an anatomical human vascular phantom.

OBJECTIVE: To experimentally evaluate three different contrast injection protocols at thoraco-abdominal high-pitch dual-source computed tomography angiography (CTA), with regard to level and homogeneity of vascular enhancement at different cardiac outputs. MATERIALS AND METHODS: A uniphasic, a biphasic as well as an individually tailored contrast protocol were tested using a human vascular phantom. Each protocol was scanned at 5 different cardiac outputs (3-5L/min, steps of 0.5L/min) using an extracorporeal cardiac pump. Vascular enhancement of the thoraco-abdominal aorta was measured every 5 cm. Overall mean enhancement of each protocol and mean enhancement for each cardiac output within each protocol were calculated. Enhancement homogeneity along the z-axis was evaluated for each cardiac output and protocol. RESULTS: Overall mean enhancement was significantly higher in the uniphasic than in the other two protocols (all p<.05), whereas the difference between the biphasic and tailored protocol was not significant (p=.76). Mean enhancement among each of the 5 cardiac outputs within each protocol was significantly different (all p<.05). Only within the tailored protocol mean enhancement differed not significantly at cardiac outputs of 3.5L/min vs. 5L/min (484 ± 25 HU vs. 476 ± 19 HU, p=.14) and 4 vs. 5L/min (443 ± 49 HU vs. 476 ± 19 HU, p=.05). Both, uniphasic and tailored protocol yielded homogenous enhancement at all cardiac outputs, whereas the biphasic protocol failed to achieve homogenous enhancement. CONCLUSION: This phantom study suggests that diagnostic and homogenous enhancement at thoraco-abdominal high-pitch dual-source CTA is feasible with either a uniphasic or an individually tailored contrast protocol.