Heparin Coating Extends the Durability of Oxygenators Used for Cardiopulmonary Support

Acomparative study was performed between a noncoated and heparin-coated cardiopulmonary support (CPS) systems with the same design and structure (Terumo Corporation, Capiox-SX series) to evaluate whether or not heparin coating extends oxygenator service life. Fifty patients underwent CPS from January 1993 until December 1997, and 54 oxygenators (Capiox-SX series) were used. There were 35 noncoated oxygenators (Group NC) and 19 heparin-coated ones (Group HC). Significant predictors for the durability of oxygenators were evaluated by a nonparametric survival analysis and a proportional hazards regression analysis. Thirteen of 35 Capiox-SX and only 2 of 19 Capiox SX-HP revealed gas transfer failure and had to be exchanged. The average life span of the Capiox-SX and Capiox-SX-HP were calculated to be 78.6 +/- 16.8 and 168 +/- 15.4 h, respectively. Group HP showed significantly longer durability than Group NC (p = 0.0017), although there were differences of perfusion index and platelet counts between the 2 groups. Heparin coating of the CPS system remained one of the 2 significant predictors (hazards ratio 8. 871, p = 0.0449) to determine the durability of oxygenators by increasing stepwise multivariate proportional hazards regression analysis, along with anemia with less than 8 g/dl hemoglobin (hazards ratio 9.438, p = 0.0173). Heparin coating of the CPS system assures improved durability because heparin-coated oxygenators have a longer service life than noncoated ones.     

Clinical Experience of Percutaneous Cardiopulmonary Support

Abstract: Recently, percutaneous cardiopulmonary support (PCPS) combined with femoro-femoral bypass without reservoir has become valued because of its quick and easy application. We developed a fully preconnected compact integrated cardiopulmonary bypass (CPB) unit (priming volume of 250 ml) with a blind pore membrane oxygenator (Kuraray Menox) for PCPS. From 1990 to 1995, PCPS was performed in 49 patients of whom 26 were weaned from support. In most cases, we applied this CICU in patients with no active bleeding (22 patients); in patients with active bleeding (n = 13), we used Medtron-ic's heparin-bonded close chest support pack (CCSP). Of these, PCPS was performed uneventfully for 2 h (median) in 8 elective cases; all of these patients were weaned or were switched to a left ventricular assist system (LVAS). In 8 urgent cases, such as those with low cardiac output syndrome, PCPS was performed for 4 days (median), 1 was weaned, and 2 CICU were cases switched to other procedures. In 32 cases of shock, 5 CICU patients were weaned, and 3 of them survived. Eight patients including 5 CICU patients and 1 CCSP patient were switched to operation or LVAS, and 2 CICU patients remain alive. From these data, PCPS has been shown to support the patient's circulation in the acute phase and earn time to switch to operation or LVAS; the quick and easy set-up of the CICU can improve the clinical results. The use of the Medtronic device broadened the indication for PCPS. The CCSP enlarged the indication of PCPS but could not improve the results. To improve the results, a heparin-bonded surface is desired.     

A Newly Developed Silicone-Coated Membrane Oxygenator for Long-Term Cardiopulmonary Bypass and Cardiac Support

Abstract: The surface of polypropylene hollow fiber was successfully coated with a very thin (0.2 μm) silicone layer. Experimental studies were performed in long-term (6 h) normothermic cardiopulmonary bypass (CPB) using 10 goats. A conventional membrane oxygenator (Mera Exce-lung HPO-lSH, MERA, Tokyo, Japan) was used for 5 goats as a control (Group C) and a new silicone-coated membrane oxygenator, which is of the same construction as that of the one used for Group C, for 5 (Group S). The O₂transfer and CO₂removal functions showed the same ranges. In the other parameters, there were no differences between the 2 groups. As for hemolysis, however, the plasma free hemoglobin of Group S was lower than that of Group C. Currently, 3 chronic percutaneous cardiopulmonary support (PCPS) experimental models have been conducted, and there has been no evidence of thromboembo-lism or deterioration of the oxygenator. In conclusion, this new oxygenator is suitable not only for CPB, but also for long-term cardiac support.     

Study of Regional Cerebral Oxygen Saturation During Percutaneous Cardiopulmonary Support

Abstract: The purpose of this study was to evaluate the change of regional cerebral oxygen saturation (rSo₂) during percutaneous cardiopulmonary support (PCPS) in patients with cardiogenic shock. Fifteen patients with cardiogenic shock were evaluated during PCPS by continuous monitoring of rSo₂, systemic venous oxygen saturation (Svo₂), and hemodynamics. The brain damage of these patients was also evaluated during and after PCPS. There were 10 males and 5 females. Their ages ranged from 57 to 79 years old (average: 60.0 ± 14). Two patients were unconscious before PCPS, and 11 received intraaortic balloon pumping (IABP) before PCPS. The change of rSo₂was significantly correlated with the change of Svo,. The average of rSo₂was 64 ± 3% at the stable hernodynamic condition. The rSo₂with pulsatile PCPS was higher than that with nonpulsatile PCPS. There was no correlation between brain damage and rSo₂. The patients with low rSo₂(40%) that resulted in poor LV function could not be weaned from PCPS. In conclusion, the continuous monitoring of rSo₂during PCPS could be a useful tool.     

Clinical Experiences of Percutaneous Cardiopulmonary Support: Its Effectiveness and Limit

In recent years, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB) and postcardiotomy cardiac support. From April 1990 to March 1997, a percutaneous cardiopulmonary support (PCPS) system was used in 20 patients with an average age of 58 years (13 males and 7 females). They comprised 11 ischemic, 6 valvular, 2 aortic, and 1 congenital heart disease patients. Our PCPS system consists of a centrifugal pump (BioMedicus BP-80), an oxygenator, and a reservoir. The entire blood contacting surface, including that of the thin wall cannulas, is coated by heparin bonded materials. As a result of this new technology, this system can be used for the long term without systemic heparinization. No major critical thrombi were revealed inside the pumps or circuits. Of the 20 patients, 7 (35%) (Group 1) could be weaned from PCPS, and the remaining 13 (Group 2) could not. In Group 1 although 2 patients suffered from renal failure and pneumonia, respectively, both were discharged from our hospital. The long-term survival rate was 35%. In Group 2 cerebral vascular damage was recognized in 3 patients, renal failure in 4, multiple system organ failure in 4, bleeding in 2, arrhythmia in 1, and leg ischemia in 2. Pulse pressure was significantly elevated due to the recovery of the native heart in Group 1, 2 days after support. However, in Group 2, it did not elevate, and the left ventricular ejection fraction was less than 30 %, associated with high left atrial pressure. In conclusion, this heparin coated PCPS system was very simple and easy to control. It demonstrated long-term biocompatibility and was very effective in recovering deteriorated cardiac function. Quicker application of this system can play an important role in preventing severe complications and obtaining better clinical results. If long-term support is necessary, a ventricular assist device (VAD), which is more powerful, durable, and biocompatible, has to be applied instead of PCPS.     

Use of Percutaneous Cardiopulmonary Support System with Rotary Blood Pump in Graft Replacement of the Descending Thoracic and Thoracoabdominal Aorta

Abstract: Graft replacement of the descending thoracic or thoracoabdominal aorta was successfully performed in 3 patients using percutaneous cardiopulmonary bypass. Femoral inflow and outflow cannulas were inserted per-cutaneously after induction of anesthesia with the patient in supine position, and low flow normothermic bypass was established before thoracotomy. Next the patient was placed in a right lateral position to create an operating field. With this body position and even an almost prone position, which was sometimes necessary for easy dissection of adhesion of lung to the aneurysmal wall, the bypass flow was easily maintained adequately. The bypass circuit was coated with heparin, and the activated clotting time (ACT) was controlled to be between 150 and 200 s during the entire operating period. Percutaneous insertion of the cannulas avoided local bleeding in the groin, and the low ACT made control of hemorrhage in the operating field easy. For descending aortic surgery, heparin-coated percutaneous cardiopulmonary bypass proved to be a useful adjunctive measure.     

Experience with Emergency Cardiac Surgery Following Institution of Percutaneous Cardiopulmonary Support

Between August 1992 and February 1998, 43 patients were treated with percutaneous cardiopulmonary support (PCPS) in our institution, and 8 of them subsequently required emergency cardiac surgery. There were 3 males and 5 females with a mean age of 63 years (range, 37 to 81 years). The etiology of shock in these 8 patients was acute myocardial infarction in 3, postinfarction left ventricular (LV) free wall rupture in 1, postinfarction ventricular septal perforation (VSP) in 1, LV free wall rupture and VSP in 1, and fatal arrhythmia due to severe aortic valvular disease in 2. The mean time interval from the onset of cardiogenic shock to the institution of PCPS was 77 min (range, 18 to 183 min). The mean time interval from the institution of PCPS until surgery was 145 min (range, 40 to 603 min). The surgical procedures were coronary artery bypass grafting (CABG) in 3 patients, closure of the LV rupture and/or closure of VSP in 3, and aortic valve replacement in 2. Six patients were weaned from PCPS, and 2 patients were discharged from the hospital (discharge rate, 25%). Although the results of emergency cardiac surgery following PCPS still are not satisfactory, we continue to apply PCPS and perform appropriate surgical procedures to improve the survival rate of the patients who would die without PCPS.     

An Aortic Balloon Catheter Incorporating a Conduit for Percutaneous Cardiopulmonary Support

Circulatory support using both intraaortic balloon pumping (IABP) and percutaneous cardiopulmonary support (PCPS) can improve general hemodynamics; however, sometimes brain damage occurs caused by hypoperfusion. Such cerebral hypoperfusion is likely to be caused by PCPS when applying the conventional femoral cannulation. We have developed a new IABP catheter which incorporates a conduit for PCPS with an outlet at the catheter tip, the goal of which is the improvement of cerebral perfusion. The hemodynamic characteristics of this new IABP catheter were compared with those of the conventional combination of IABP and PCPS. Studies were performed by mock test using a pulsatile artificial heart. A polyvinyl chloride tube acted as the aorta with 2 branches at the proximal and distal portions representing the upper and lower portions of the body. The IABP balloon was positioned between the 2 branches, and changes in flow at the 2 branches were examined at varying PCPS flow rates. Flow in the proximal branch using the new device was greater than it was using the conventional PCPS device. We conclude that cerebral perfusion could be improved with the use of this new special IABP catheter.     

Percutaneous Cardiopulmonary Support as the Second Generation of Venoarterial Bypass: Current Status and Future Direction

Abstract: We have developed a new percutaneous cardiopulmonary support (PCPS) system in cooperation with Terumo Corporation, called the Emergency Bypass System (EBS). This preassembled system is unique in terms of its small priming volume (470 cc), fully automatic priming function, originally developed membrane oxygenator, and Capiox straight path centrifugal pump. The priming process takes only 5 min. We have used this system in 4 patients (all were male; mean age 56 years, range 35–73 years). The duration of assist ranged from 15 min to 210 h. Maximum bypass flow ranged from 2.2 to 3.6 L/min, systemic circulation was very well maintained, and urinary output was acceptable. Although the centrifugal pump was in good working condition, we had to change the oxygenator because of serum leakage 36 to 48 h after initiation of the assist. One patient was weaned from the PCPS, but died of brain death. The other patients could not be weaned from the PCPS. The cause of death in these patients was irreversible myocardial damage. Disseminated intravascular coagulopathy triggered by surgical trauma related to various procedures developed in 2 patients during assist and was the cause of cessation of the assist. Problems to be ratified and future directions in the EBS and PCPS were earlier introduction through the establishment of clear indications and endpoint, heparin coating, improvement in durability of the oxygenator, and cost.     

Various Problems During Long-Term Percutaneous Cardiopulmonary Support

Abstract: A 54-year-old man with a left ventricular free wall rupture following acute anterior myocardial infarction underwent a repair surgery with percutaneous cardiopulmonary support (PCPS). During surgery and postoperatively, PCPS provided sufficient support flow. The patient was successfully weaned from PCPS on the 15th postoperative day and discharged subsequently. In the management of cardiac rupture patients, PCPS has the merit of preventing rupture progression and the advantage of recovery of pulmonary function. However, there are several problems to solve. The support effectiveness and recovery of the patient's heart should be carefully evaluated. Effective left heart decompression also needs to be established. Heparin-coated circuits still need proper anticoagula-tion treatment to prevent thrombus formation especially while support flow is low. A circuit construction that allows easier maintenance and safer exchange of oxygen-ators and pump heads is suggested. Ischemia of the cannulated leg should be prevented by femoral artery perfusion.     

Out-of-Hospital Cardiopulmonary Arrest Due to Penetrating Cardiac Injury Treated by Percutaneous Cardiopulmonary Support in the Emergency Room: Report of a Case

Penetrating cardiac injury tends to generally be repaired without cardiopulmonary bypass in the operating room. We herein report the case of penetrating cardiac injury repaired using percutaneous cardiopulmonary support in an emergency room. A 57-year-old man attempted suicide by stabbing himself in the left anterior chest with a knife. Although the patient suffered cardiopulmonary arrest for 7 min in the ambulance, spontaneous circulation was restored following pericardiotomy through emergency left thoracotomy in the emergency room. To prevent coronary artery injury and control the massive bleeding, percutaneous cardiopulmonary support was instituted without systemic heparinization and the cardiac injury was repaired in the emergency room. The patient was then transferred to another hospital on day 46 for further rehabilitation. Percutaneous cardiopulmonary support might be helpful for treating critical patients in an emergency room, even in the case of trauma patients.     

Impact of Distinct Oxygenators on Pulsatile Energy Indicators in an Adult Cardiopulmonary Bypass Model

The quantification of pulse energy during cardiopulmonary bypass (CPB) post‐oxygenator is required prior to the evaluation of the possible beneficial effects of pulsatile flow on patient outcome. We therefore, evaluated the impact of three distinctive oxygenators on the energy indicators energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) in an adult CPB model under both pulsatile and laminar flow conditions. The pre‐ and post‐oxygenator pressure and flow were measured at room temperature using a 40% glycerin‐water mixture at flow rates of 1, 2, 3, 4, 5, and 6 L/min. The pulse settings at frequencies of 40, 50, 60, 70, and 80 beats per minute were according to the internal algorithm of the Sorin CP5 centrifugal pump. The EEP is equal to the mean pressure, hence no SHE is present under laminar flow conditions. The Quadrox‐i Adult oxygenator was associated with the highest preservation of pulsatile energy irrespective of flow rates. The low pressure drop–high compliant Quadrox‐i Adult oxygenator shows the best SHE performance at flow rates of 5 and 6 L/min, while the intermediate pressure drop–low compliant Fusion oxygenator and the high pressure drop–low compliant Inspire 8F oxygenator behave optimally at flow rates of 5 L/min and up to 4 L/min, respectively. In conclusion, our findings contributed to studies focusing on SHE values post‐oxygenator as well as post‐cannula in clinical practice. In addition, our findings may give guidance to the clinical perfusionist for oxygenator selection prior to pulsatile CPB based on the calculated flow rate for the individual patient.     

Clinical Evaluation of New Generation Oxygenators With Integrated Arterial Line Filters for Cardiopulmonary Bypass

New generation oxygenators with integrated arterial line filters have been marketed to improve the efficacy of cardiopulmonary bypass (CPB). Differences in designs, materials, coating surfaces, pore size of arterial filter, and static prime exist between the oxygenators. Despite abundant preclinical data, literature lacks clinical studies. From September 2010 to March 2011, 80 consecutive patients were randomized to CPB using Terumo Capiox FX25 (40 patients, Group‐T) or Sorin Synthesis (40 patients, Group‐S) oxygenators. Pressure drop and gas exchange efficacy were registered during CPB. High‐sensitivity C‐reactive protein (hs‐CRP), white blood cells (WBCs), fluid balance, activated clotting time, international normalized ratio (INR), activated partial thromboplastin time (aPTT), fibrinogen, platelets (PLTs), serum albumin, and total proteins were measured perioperatively at different timepoints. Clinical outcome was recorded. Repeated measure analysis of variance and nonparametric statistics assessed between‐groups and during time differences. The two groups showed similar baseline and intraoperative variables. No differences were recorded in pressure drop and gas exchange (group‐P and group*time‐P = N.S. for all) during CPB. Despite similar fluid balance (P = N.S. for static/dynamic priming and ΔVolume administered intraoperatively), Group‐T showed higher hs‐CRP (group‐P = 0.034), aPTT (group‐P = 0.0001), and INR (group‐P = 0.05), with lower serum albumin (group‐P = 0.014), total proteins (group‐P = 0.0001), fibrinogen (group‐P = 0.041), and PLTs (group‐P = 0.021). Group‐T also showed higher postoperative bleeding (group‐P = 0.009) and need for transfusions (P = 0.008 for packed red cells and P = 0.0001 for fresh frozen plasma and total transfused volumes). However, clinical outcome was comparable (P = N.S. for all clinical endpoints). Both oxygenators proved effective and resulted in comparable clinical outcomes. However, Sorin Synthesis seems to reduce inflammation and better preserve the coagulative cascade and serum proteins, resulting in lower transfusions and post‐CPB inflammatory response.     

A Novel Blood Viscosity Estimation Method Based on Pressure‐Flow Characteristics of an Oxygenator During Cardiopulmonary Bypass

During cardiopulmonary bypass (CPB), blood viscosity conspicuously increases and decreases due to changes in hematocrit and blood temperature. Nevertheless, blood viscosity is typically not evaluated, because there is no technology that can provide simple, continuous, noncontact monitoring. We modeled the pressure‐flow characteristics of an oxygenator in a previous study, and in that study we quantified the influence of viscosity on oxygenator function. The pressure‐flow monitoring information in the oxygenator is derived from our model and enables the estimation of viscosity. The viscosity estimation method was proposed and investigated in an in vitro experiment. Three samples of whole bovine blood with different hematocrit levels (21.8, 31.0, and 39.8%) were prepared and perfused into the oxygenator. As the temperature changed from 37°C to 27°C, the mean inlet pressure (P_in) and outlet pressure (P_out) of the oxygenator and the flow (Q) and viscosity of the blood were measured. The estimated viscosity was calculated from the pressure gradient (ΔP = P_in ? P_out) and Q and was compared to the measured blood viscosity. A strong correlation was found between the two methods for all samples. Bland‐Altman analysis revealed a mean bias of ?0.0263 mPa.s, a standard deviation of 0.071 mPa.s, limits of agreement of ?0.114–0.166 mPa.s, and a percent error of 5%. Therefore, this method is considered compatible with the torsional oscillation viscometer that has plus or minus 5% measurement accuracy. Our study offers the possibility of continuously estimating blood viscosity during CPB.     

Clinical Comparison of Blood Oxygenators: A Retrospective Study

Abstract: The results for platelet count (PC), activated clotting time (ACT), postoperative bleeding, and hemo-derivatives usage in cardiac surgeries were crossed against the type of oxygenator used. These were two bubble and one membrane type. A sample of the surgery population for each type was selected at random. Thus, the patients in this study were divided into 3 groups: BA: 87 patients, bubble oxygenator; BB: 87 patients, bubble oxygenator; M: 73 patients, membrane oxygenator. The groups were statistically similar (p < 0.05) for age, body surface area, cardiopulmonary bypass (CPB) time, and prevalence of cardiac disease. The rate of PC 15 min after CPB end and before its beginning was BA, 0.48 ± 0.02; BB, 0.49 ± 0.02; M, 0.55 ± 0.03. The rate of ACT after protamine administration and before CPB was BA, 1.22 ± 0.03; BB, 1.16 ± 0.03; M, 1.16 ± 0.03. Volume (ml) of total postoperative bleeding (POB) was BA, 904 ± 72; BB, 963 ± 73; M, 867 ± 83. Patient percentage that used hemoderivatives (HD) was BA, 86.3%; BB, 88.5%; M, 90.0%. No statistical difference was found between groups (p > 0.05). This study indicates that although membrane oxygenators have better theoretic and experimental biocompatibility, no significant difference in PC, ACT, POB, and HD usage was observed in the clinical setting. All values are expressed as the mean ± standard error of the mean.     

Results of Circulatory Support for Postoperative Cardiogenic Shock

Abstract: Over the last 5 years, 15 patients received ventricular assist devices (VADs) (Group 1) and 5 percutaneous cardiopulmonary support (CPS) (Group 2) while in postoperative cardiogenic shock. Group 1 consisted of 8 men and 7 women ranging in age from 22 to 73 years (average age, 55 years). Nine of these patients underwent surgery for valve replacement, 5 for coronary artery bypass grafting, and 1 for closure of a ventricular septal rupture. The duration of VAD support ranged from 6 h to 9 days (mean, 3. 9 days). Group 2 consisted of 4 men and 1 woman ranging in age from 49 to 68 years (average age, 57 years). One of these patients underwent surgery for valve replacement, 1 for coronary artery bypass grafting, 2 for replacement of a thoracic aneurysm, and 1 for left ventricular aneurysmectomy. The duration of CPS ranged from 4 h to 8 days (mean, 2. 8 days). In Group 1, 13 patients were weaned from the VADs and 8 survived. Bleeding occurred in 5 patients, renal failure in 4, infection in 3, cardiac failure in 4, cerebral infarction in 1, perioperative myocardial infarction in 1, arrhythmia in 1, and ileus in 1. In Group 2, 4 patients were weaned from the CPS and 3 survived. Bleeding occurred in 3 patients, renal failure in 2, CNS injury in 2, and cardiopulmonary failure in 1. The 8 survivors in Group 1 have been followed for 2 to 56 months (mean, 28. 7 months). Five patients were in NYHA class I, 2 were in class II, and 1 was in class III. The 3 survivors in Group 2 have been followed for 6 to 18 months (mean, 10. 6 months). Two of these patients were in NYHA class I, and 1 was in class III. The VADs and CPS were both effective in preventing circulatory failure, but serious complications were observed more frequently in patients with CPS.     

Emergency Percutaneous Cardiopulmonary Bypass Support for Acute Myocardial Infarction

(Received for publication on Apr. 28, 1997; accepted on Nov. 6, 1997)     

Mechanical Circulatory Support for Severe Heart Failure After Operation

To evaluate the clinical results of circulatory support for severe heart failure after operation, we examined 62 patients (39 males and 23 females) who underwent circulatory support for postoperative heart failure from 1984 to 1996. Their ages ranged from 22 to 78 (mean 52) years. In 62 patients, 35 had valvular, 25 had ischemic, and 2 had congenital heart disease. Postoperation, 29 patients underwent venoarterial bypass (VAB), 20 had biventricular bypass (BVB), and 8 had left ventricular bypass (LVB). The remaining 5 patients received a pulsatile left ventricular assist device (LVAD). The weaning and discharge rates of the patients by type of support were 51.7% and 31.0% with VAB, 75.0% and 55.0% with BVB, 87.5% and 37.5% with LVB, and 60.0% and 40.0% with LVAD, respectively. The complete results of this series (64.5% weaning rate and 40.3% discharge rate) were acceptable.