A new system for right atrial cooling

Purpose. Controlled hypothermia of the right atrium has been shown to reduce postoperative atrial fibrillation after on-pump coronary artery bypass grafting. A device has been developed that couples right atrial and nodal cooling with modified dual-stage venous drainage by circulating cold sterile saline through an intracavity, shape-memory balloon. Description. The atrial cooling device was used in 41 patients undergoing elective coronary artery bypass grafting. Systemic temperatures were held at 36 degrees C, and temperatures of atrial structures were reduced to about 19 degrees to 20 degrees C at 30 minutes. Evaluation. Electrical activity was effectively suppressed during cross-clamp by controlled cooling of the right atrium. Hemodilution was reduced by right atrial isolation and collection of crystalloid cardioplegia. Cardiac electrical activity returned without sustained arrhythmias in all patients. Postoperative atrial fibrillation developed in only 3 of the 38 patients. Conclusions. The results indicate that local atrial cooling may contribute to protection of the right atrium, subsequently reducing the incidence of transient postoperative atrial fibrillation

In vitro air removal characteristics of two neonatal cardiopulmonary bypass systems:filtration may lead to fractionation of bubbles

Introduction of gaseous microemboli (GME) into the arterial line of a pediatric cardiopulmonary bypass (CPB) circuit may lead to cognitive decline and adverse outcomes of the pediatric patient. Arterial filters are incorporated into CPB circuits as a safeguard for gross air and to reduce GME. Recently, arterial filters were integrated in two neonatal oxygenators to reduce volume and foreign surface area. In this study a clinical CPB scenario was simulated. The oxygenators, the corresponding venous reservoirs and the complete CPB circuits were compared regarding air removal and bubble size distribution after the introduction of an air bolus or GME. During a GME challenge, the Capiox FX05 oxygenator removed a significantly higher volume of GME than the QUADROX-i Neonatal oxygenator (97% vs. 86%). Detailed air removal characteristics showed that more GME in the range of 20-50 mu m were leaving the devices than were entering. This phenomenon seems to be more present in the Capiox FX05. The circuits were also challenged with an air bolus. Each individual component tested removed 99.9%, which resulted in an air volume reduction of 99.99% by either complete CBP circuit. Overall, we conclude that both CPB systems were very adequate in removing GME and gross air. The air removal properties of both systems are considered safe and reliable. Detailed GME distribution data show that the Capiox FX05 showed more small GME

Effect of Oxygenator Size on Air Removal Characteristics: A Clinical Evaluation

During cardiopulmonary bypass (CPB), gaseous microemboli (GME) are released into the patients' arterial bloodstream. Gaseous microemboli may contribute to the adverse outcome after cardiac surgery. Recently, two oxygenator models with or without integrated arterial filter (IAF) were designed and only differ in size, leading to a change of 20% in surface area of the hollow fibers and 25% in blood velocities. The aim of this study was to assess the air removal characteristics of the inspire oxygenators with or without IAF. Sixty-eight patients were randomly assigned to four different groups: optimized adult and full adult and an additional IAF. Gaseous microemboli reduction rates were measured with a bubble counter. The number of GME reduction rates showed no differences. However, both models reduced significantly less volume of GME (optimized adult: 40.6% and full adult: 50.3%) compared with both models with IAF (88.7% and 88.5%, respectively). No significant differences of reduction rates were found between both devices without IAF and also not between both models with IAF. In conclusion, the larger inspire oxygenator tends to remove more GME. No effect from size of oxygenator device with integrated screen filter on GME reduction was observed. The inspire oxygenators with IAF may be considered as an adequate GME filte

Clinical evaluation of the air-handling properties of contemporary oxygenators with integrated arterial filter

Gaseous microemboli (GME) may originate from the extracorporeal circuit and enter the arterial circulation of the patient. GME are thought to contribute to cerebral deficit and to adverse outcome after cardiac surgery. The arterial filter is a specially designed component for removing both gaseous and solid microemboli. Integration of an arterial filter with an oxygenator is a contemporary concept, reducing both prime volume and foreign surface area. This study aims to determine the air-handling properties of four contemporary oxygenator devices with an integrated arterial filter. Two oxygenator devices, the Capiox FX25 and the Fusion, showed significant increased volume of GME reduction rates (95.03 +/- 3.13% and 95.74 +/- 2.69%, respectively) compared with both the Quadrox-IF (85.23 +/- 5.84%) and the Inspire 6F M (84.41 +/- 12.93%). Notably, both the Quadrox-IF and the Inspire 6F M as well as the Capiox FX 25 and the Fusion showed very similar characteristics in volume and number reduction rates and in detailed distribution properties. The Capiox FX25 and the Fusion devices showed significantly increased number and volume reduction rates compared with the Quadrox-IF and the Inspire 6F M devices. Despite the large differences in design of all four devices, our study results suggest that the oxygenator devices can be subdivided into two groups based on their fibre design, which results in screen filter (Quadrox-IF and Inspire 6F M) and depth filter (Capiox FX25 and Fusion) properties. Depth filter properties, as present in the Capiox FX25 and Fusion devices, reduced fractionation of air and may ameliorate GME remova

Comparison of Warm Blood Cardioplegia Delivery With or Without the Use of a Roller Pump

Various techniques for administration of blood cardioplegia are used worldwide. In this study, the effect of warm blood cardioplegia administration with or without the use of a roller pump on perioperative myocardial injury was studied in patients undergoing coronary artery bypass grafting using minimal extra-corporeal circuits (MECCs). Sixty-eight patients undergoing elective coronary bypass surgery with an MECC system were consecutively enrolled and randomized into a pumpless group (PL group: blood cardioplegia administration without roller pump) or roller pump group (RP group: blood cardioplegia administration with roller pump). No statistically significant differences were found between the PL group and RP group regarding release of cardiac biomarkers. Maximum postoperative biomarker values reached at T1 (after arrival intensive care unit) for heart-type fatty acid binding protein (2.7 [1.5; 6.0] ng/mL PL group vs. 3.2 [1.6; 6.3] ng/mL RP group, p = .63) and at T3 (first postoperative day) for troponin T high-sensitive (22.0 [14.5; 29.3] ng/L PL group vs. 21.1 [15.3; 31.6] ng/L RP group, p = .91), N-terminal pro-brain natriuretic peptide (2.1 [1.7; 2.9] ng/mL PL group vs. 2.6 [1.6; 3.6] ng/mL RP group, p = .48), and C-reactive protein (138 [106; 175] μg/mL PL group vs. 129 [105; 161] μg/mL RP group, p = .65). Besides this, blood cardioplegia flow, blood cardioplegia line pressure, and aortic root pressure during blood cardioplegia administration were similar between the two groups. Administration of warm blood cardioplegia with or without the use of a roller pump results in similar clinically acceptable myocardial protection

Carbon Dioxide Flush of an Integrated Minimized Perfusion Circuit Prior to Priming Prevents Spontaneous Air Release Into the Arterial Line During Clinical Use

Recently, an oxygenator with an integrated centrifugal blood pump (IP) was designed to minimize priming volume and to reduce blood foreign surface contact even further. The use of this oxygenator with or without integrated arterial filter was compared with a conventional oxygenator and nonintegrated centrifugal pump. To compare the air removal characteristics 60 patients undergoing coronary artery bypass grafting were alternately assigned into one of three groups to be perfused with a minimized extracorporeal circuit either with the conventional oxygenator, the oxygenator with IP, or the oxygenator with IP plus integrated arterial filter (IAF). Air entering and leaving the three devices was measured accurately with a bubble counter during cardiopulmonary bypass. No significant differences between all groups were detected, considering air entering the devices. Our major finding was that in both integrated devices groups incidental spontaneous release of air into the arterial line in approximately 40% of the patients was observed. Here, detectable bolus air (>500 µm) was shown in the arterial line, whereas in the minimal extracorporeal circulation circuit (MECC) group this phenomenon was not present. We decided to conduct an amendment of the initial design with METC-approval. Ten patients were assigned to be perfused with an oxygenator with IP and IAF. Importantly, the integrated perfusion systems used in these patients were flushed with carbon dioxide (CO2 ) prior to priming of the systems. In the group with CO2 flush no spontaneous air release was observed in all cases and this was significantly different from the initial study with the group with the integrated device and IAF. This suggests that air spilling may be caused by residual air in the integrated device. In conclusion, integration of a blood pump may cause spontaneous release of large air bubbles (>500 µm) into the arterial line, despite the presence of an integrated arterial filter. CO2 flushing of an integrated cardiopulmonary bypass system prior to priming may prevent spontaneous air release and is strongly recommended to secure patient safet

Attenuated renal and intestinal injury after use of a mini-cardiopulmonary bypass system

Background. Transient, subclinical myocardial, renal, intestinal, and hepatic tissue injury and impaired homeostasis is detectable even in low-risk patients undergoing conventional cardiopulmonary bypass (CPB). Small extracorporeal closed circuits with low priming volumes and optimized perfusion have been developed to reduce deleterious effects of CPB. Methods. A prospective, randomized trial was conducted in 49 patients undergoing elective coronary artery bypass graft surgery either with the use of a standard or mini-CPB system (Synergy). We determined early postoperative inflammatory response (leukocytosis, C-reactive protein, urine interleukin-6), platelet consumption and activation (urine thromboxane B2), proximal renal tubular injury (urine N-acetyl-glucosaminidase), and intestinal injury (intestinal fatty acid binding protein). Results. In patients undergoing coronary artery bypass grafting with a mini-CPB system, we observed decreased priming volumes with subsequent attenuation of on-pump hemodilution, improved hemostatic status with reduced platelet consumption and platelet activation, decreased postoperative bleeding and minimized transfusion requirements. We also found reduced leukocytosis and decreased urinary interleukin-6. Levels of urine N-acetyl-glucosaminidase were on average threefold lower, and urinary intestinal fatty acid binding protein was 40% decreased in the patients on the mini-CPB system, as compared with standard CPB. Conclusions. The use of the mini-CPB system during myocardial revascularization represents a viable non-pharmacologic strategy that can attenuate the alterations in the hemostatic system, reduce bleeding and transfusion requirements, decrease systemic inflammatory response, and reduce immediate postoperative renal and intestinal tissue injury

Strategies to Improve Survival from Surgery for Heart Valve Implantation in Sheep

Sheep are a commonly used and validated model for cardiovascular research and, more specifically, for heart valve research. Implanting a heart valve on the arrested heart in sheep is complex and is often complicated by difficulties in restarting the heart, causing significant on-table mortality. Therefore, optimal cardioprotective management during heart valve implantation in sheep is essential. However, little is known about successful cardioprotective management techniques in sheep. This article reports our experience in the cardioprotective management of 20 female sheep that underwent surgical aortic valve replacement with a stented tissue-engineered heart valve prosthesis. During this series of experiments, we modified our cardioprotection protocol to improve survival. We emphasize the importance of total body hypothermia and external cooling of the heart. Furthermore, we recommend repeated cardioplegia administration at 20 min intervals during surgery, with the final dosage of cardioplegia given immediately before the de-clamping of the aorta. To reduce the number of defibrillator shocks during a state of ventricular fibrillation (VF), we have learned to restart the heart by reclamping the aorta, administering cardioplegia until cardiac arrest, and de-clamping the aorta thereafter. Despite these encouraging results, more research is needed to finalize a protocol for this procedure