Bingyang Ji

Review Article: Comparison of perfusion modes on microcirculation during acute and chronic cardiac support: is there a difference?

Although heart-lung machines and cardiac assist devices have been used successfully for acute and chronic cardiac support for decades, controversies still remain concerning the benefits of pulsatile and non-pulsatile perfusion. The core of the debate is whether enough energy is generated by the artificial pulse to keep capillary beds open and cell metabolism stabilized during acute or chronic cardiac support. In other words, does artificial pulsatility exist in the microcirculation: small vessels of less than 100 μm in diameter? Many investigators have tried to use different tools and biomarkers to reflect directly or indirectly the state of the microcirculation when comparing the two different perfusion modes during acute and chronic cardiac support. However, the results are controversial. First, direct observation of the state of the microcirculation during acute and chronic cardiac support is limited; and reports concerning direct observation of the microcirculation with different perfusion modes in contemporary literature are rare. Secondly, different investigators have used their own criteria to define pulsatile flow. Therefore, it is necessary to develop more efficient methodologies, enabling direct observation of the microcirculation during acute and chronic cardiac support and also establish common criteria that will precisely quantify the pulsatile flow in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) levels. Using these critical parameters may explain how excess energy is created by pulsatile flow and maintains perfusion through the microcirculation by ensuring capillary patency. Perfusion (2007) 22, 115—119.

Clinical evaluation of two different extracorporeal membrane oxygenation systems: a single center report.

Refinements in extracorporeal membrane oxygenation (ECMO) equipment, including heparin-coated surfaces, centrifugal pump, membrane oxygenator, and more biocompatible pump-oxygenator circuits, have reduced procedure-related complications and have made ECMO a safe and effective therapy for critical patients. The aim of this study was to evaluate the performance of two different ECMO circuit systems in a clinical setting and compare their outcomes. From December 2004 to December 2009, 121 patients required ECMO for primary or postcardiotomy cardiogenic shock at our heart center. We used the Medtronic circuit system in our earlier series (Group M, n = 64), and from July 2007, ECMO was carried out mainly with the Quadrox D PLS circuit system (Group Q, n = 56). We retrospectively summarized and analyzed the data of these patients. The evaluation was based on the comparison between properties of the membrane oxygenators and pumps, anticoagulation therapy, circuit-related complications, and clinical outcomes. Support pump flow rates, platelet counts, and trans-membrane pressure drops (TMPDs) of preoxygenator and postoxygenator pressures were compared between two groups at the time of support established (T1) and support established for 24 h (T2). There were no significant differences between the two groups with regard to patient characteristics and pre-ECMO data. The support pump flow rates and platelet counts at different times were comparable in the two groups. The cannulation technique, ECMO duration, and mean heparin dosage were similar in both groups. There were also no significant differences between the groups in mortality or complications related to bleeding and organ dysfunction. Compared with the M group, the Q group experienced less mechanical failure of the ECMO circuit. The Quadrox PLS circuit system showed less circuit thrombus formation (P < 0.045), less plasma leakage (P < 0.001), and less need for replacement of oxygenators (P < 0.001). Furthermore, frequency of hemolysis during ECMO was significantly lower (P < 0.045). In addition, at T1 and T2, TMPDs were significantly lower in the Q group. Our results suggest that both ECMO circuit systems provide similar effects for safe clinical application, but the Quadrox PLS ECMO circuit system demonstrated partially improved biocompatibility in terms of improved cell preservation, lower TMPDs, less plasma leakage, and thrombus formation.

The effect of preprocessing stored red blood cells on neonates undergoing corrective cardiac surgery.

This study compared the effect of unprocessed and processed packed red blood cells (PRBCs) with the continuous autotransfusion system (CATS) during neonate heart surgery. Sixteen neonatal patients undergoing cardiac surgery were randomly divided into two groups: unprocessed PRBC (C group, n = 8); processed PRBC (P group, n = 8). The CATS was employed perioperatively. Series laboratory and clinical parameters, including levels of hematocrit, blood potassium, blood glucose, blood lactate, acid-base, and total priming volume of PRBC, were used to compare the effect between the two groups. Before CPB, the hematocrit of processed PRBCs in P group was significantly higher than those in C group (p < 0.01), and the concentrations of potassium, blood glucose, and lactate of processed PRBCs in P group were significantly lower than those in C group (p < 0.01). At the beginning and the end of CPB, the hematocrit levels in P group were all higher than those in C group (p < 0.05); lactate levels in P group were significantly lower than those in C group at the beginning of CPB (p < 0.01), and lower than that of C group at the end of CPB (p < 0.05). The total priming of PRBCs in P group was significantly less than that in C group (p < 0.01). Perioperative processing with CATS provided a high-quality RBC concentration, decreased the total priming of PRBCs, providing increased high-quality blood salvage during neonatal CPB procedure.

Application of modified perfusion technique on one stage repair of interrupted aortic arch in infants: a case series and literature review.

One stage repair of interrupted aortic arch (IAA) associated with cardiac anomalies in neonates and infants is challenging for the entire surgical team. Deep hypothermic circulatory arrest (DHCA) prolongs myocardial and cerebral ischemia and may induce heart, brain, and major organ dysfunction. From May 2004 to May 2006, 13 infants with IAA underwent one stage repair by median sternotomy under DHCA with continuous regional cerebral perfusion (RCP) in Fuwai Children’s Heart Center. Median age at operation was 10.4 ± 6.7 months, and mean body weight was 6.58 ± 2.15 kg. Temperature of nasopharynx was decreased to 18°C–20°C; rectal temperature was controlled at 19°C–22°C. Flow rate of RCP was maintained with 20–25 ml · kg−1 · min−1 under DHCA combined with RCP. Mean artery pressure (MAP) measuring from right radial artery was 32.5 ± 5.8 mm Hg, and MAP from femoral artery was 11.2 ± 3.5 mm Hg. Mean cardiopulmonary bypass (CPB) time was 141.6 ± 21.7 min, and mean aortic clamp time was 52.3 ± 10.9 min. Mean duration of RCP was 31.5 ± 12.4 min. Mean intubation time in intensive care unit (ICU) was 54.7 ± 12.6 hours, and mean ICU stay was 67.9 ± 28.4 hours. This report describes our CPB protocol under DHCA using continuous RCP in low weight pediatric patients to minimize neurological complications during one stage IAA repair and summarizes the various CPB managements in recent literature as well.

Real-time continuous neuromonitoring combines transcranial cerebral Doppler with near-infrared spectroscopy cerebral oxygen saturation during total aortic arch replacement procedure: a pilot study.

The purpose of this investigation was to use combined transcranial cerebral Doppler (TCD) and near-infrared spectroscopy cerebral oxygen saturation (NIRS) during total aortic arch replacement (TAAR) to monitor middle cerebral artery blood flow velocity and regional cerebral oximetry (rSO2) changes to provide a clinical basis for protective measures that may decrease injury of the central nervous system. Consecutive 12 adult patients underwent deep hypothermic circulatory arrest (DHCA) and antegrade selective cerebral perfusion (ASCP) during TAAR. A TCD probe was placed at the temporal windows after induction of anesthesia and the NIRS probe placed on the forehead of patients to collect perioperative, intraoperative, and postoperative hemodynamic parameters, and cerebral blood flow (CBF) and rSO2 during cardiopulmonary bypass (CPB). In this retrospective case series, all patients survived, and there were no postoperative neurologic complications. There was no significant correlation between the mean arterial pressure and rSO2. The middle cerebral artery mean velocity (VmMCA) and rSO2 were significantly correlated, and main pump flow significantly correlated with rSO2. After ASCP, VmMCA, rSO2, and venous oxygen saturation were significantly lower than before ASCP, but VmMCA and rSO2 returned to pre-CPB levels postoperatively. After off pump, the flow of ASCP showed a significant positive correlation with VmMCA and rSO2. During DHCA when ASCP flow was lower than 5 ml/kg/min, TCD could not detect the MCA blood flow signal. When the flow of ASCP was above keeping around 10 ml/kg/min, MCA CBF velocity was maintained and rSO2 > 45%. The combination of TCD and NIRS can be effective in monitoring brain function during DHCA with ASCP and may provide a guide for decreasing brain injury during the TAAR procedure.

Acidic buffer or plus cyclosporine A post-conditioning protects isolated rat hearts against ischemia-reperfusion injury.

BACKGROUND It is well documented that transient acidosis during reperfusion is protective. The aim of this study was to evaluate the cardioprotection of acidic buffer or plus cyclosporine A in isolated rat hearts after cardioplegic arrest. METHODS Langendorff-perfused Sprague-Dawley rat hearts were perfused for 20 min with Krebs-Henseleit (K-H) buffer followed by 30 min of crystalloid cardioplegia and 60 min of reperfusion. Control hearts were perfused with Krebs-Henseleit buffer. Acidic buffer post-conditioning hearts were perfused with acidic K-H buffer (pH 6.8) for the first 3 min of reperfusion. Acidic buffer plus cyclosporine A hearts were perfused with K-H acidic buffer (pH 6.8) containing cyclosporine A (0.2 μmol/L) for the first 3 min of reperfusion. RESULTS Compared with the control group, acidic buffer or plus cyclosporine A post-conditioning significantly improved myocardial performance, decreased cytochrome C release into the cytosol, increased Bcl-2 expression and decreased Bax expression, decreased sensitivity of mPTP-opening to [Ca2+] and the rate of apoptosis after reperfusion. CONCLUSION These findings suggested that acidic buffer or plus cyclosporine A post-conditioning prevented apoptosis-related mitochondrial permeabilization and provided the myocardial protection after cardioplegic arrest.Background: It is well documented that transient acidosis during reperfusion is protective. The aim of this study was to evaluate the cardioprotection of acidic buffer or plus cyclosporine A in isolated rat hearts after cardioplegic arrest. Methods: Langendorff-perfused Sprague–Dawley rat hearts were perfused for 20 min with Krebs–Henseleit (K-H) buffer followed by 30 min of crystalloid cardioplegia and 60 min of reperfusion. Control hearts were perfused with Krebs–Henseleit buffer. Acidic buffer post-conditioning hearts were perfused with acidic K-H buffer (pH 6.8) for the first 3 min of reperfusion. Acidic buffer plus cyclosporine A hearts were perfused with K-H acidic buffer (pH 6.8) containing cyclosporine A (0.2 μmol/L) for the first 3 min of reperfusion. Results: Compared with the control group, acidic buffer or plus cyclosporine A post-conditioning significantly improved myocardial performance, decreased cytochrome C release into the cytosol, increased Bcl-2 expression and decreased Bax expression, decreased sensitivity of mPTP-opening to [Ca2+] and the rate of apoptosis after reperfusion. Conclusion: These findings suggested that acidic buffer or plus cyclosporine A post-conditioning prevented apoptosisrelated mitochondrial permeabilization and provided the myocardial protection after cardioplegic arrest.

Myocardial protective effects of nicorandil, an opener of potassium channels on senile rat heart

The purpose of this study was to investigate the cardio-protective effects of nicorandil, an opener of potassium channels, on senile rat hearts from ischemic reperfusion injury. A modified working model of isolated perfused hearts of senile rats was used. After isolation, the hearts underwent 60 min of global hypothermic ischemia treatment, followed by 30 min of reperfusion. These hearts were distributed into three groups, each receiving different cardioplegic solutions: (1) St. Thomas’ solution (Group S), (2) 100 μmol/L nicorandil (Group N), (3) St. Thomas’ solution combined with 100 μmol/L nicorandil (Group S+N). The pre- and post-ischemic myocardial function were assessed by the percentage recovery of the heart rate (HR), ±dp/dtmax (maximal rate of change of left ventricular pressure) and cardiac output (CO). Upon reperfusion, the cardioplegic solution was collected from the coronary sinus and tested for lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) activity. During 30 min of reperfusion, the percentage recovery of HR, +dp/dt and left ventricular stroke work (LVSW) were significantly higher in Group S+N than in Group S and Group N (p < 0.05). The percentage of recovery in CO was higher in Group N and Group S+N than in Group S. The electrical activities arresting time (EAT) and mechanical activities arresting time (MAT) were longer in Group N than in Group S and Group N+S(p < 0.01). There were no statistical significance between Group S and Group N+ S(p > 0.05). There were no significant differences in the levels of LDH and CK-MB. Electron microscopic examination revealed better preservation of the ultra-structures of the myocardial tissue in Group N+S than the other two groups. These results indicate that nicorandil combined with St. Thomas’ solution can improve the left ventricular function of the post-ischemic senile rat and offer a better myocardial protective effect on the ischemic senile myocardium.

Pharmacological postconditioning protects isolated rat hearts against ischemia-reperfusion injury: the role of mitochondrial permeability transition pore.

Postconditioning has been verified to provide cardioprotection and is associated with the state of mitochondrial permeability transition pore. However, there are a few limitations with clinical use of classic postconditioning; therefore, the purpose of this investigation was to study whether inhibition of mitochondrial permeability transition pore opening with cyclosporine A also provided cardioprotection. Langendorff-perfused Sprague–Dawley rat hearts were perfused for 20 minutes with Krebs–Henseleit buffer followed by 30 minutes of crystalloid cardioplegia and 60 minutes of reperfusion. Control hearts (Con group) were reperfused with Krebs– Henseleit buffer. Postconditioning hearts (Ipo group) were with six cycles of 10 seconds reocclusion separated by 10 seconds perfusion before reperfusion. Cyclosporine A postconditioning hearts (CsA group) were reperfused with Krebs–Henseleit buffer containing 0.8 &mgr;mol/L cyclosporine A at first 5 minutes of reperfusion. Compared with Con group, myocardial performance was better preserved in CsA group. Mitochondrial outer membrane integrity was preserved, with less cytosolic diffusion of cytochrome C (p < 0.05) and less frequency of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate (dUTP) nick end labeling–positive myocytes in Ipo and CsA group (p < 0.05). Postconditioning prevented apoptosis-related mitochondrial permeabilization and dysfunction after cardioplegic arrest. Cyclosporine A postconditioning had a better effect than classic postconditioning in myocardial performance.

The application of a modified technique of SCP under DHCA during total aortic arch replacement combined with stented elephant trunk implantation.

We reviewed the perfusion experiences of 60 cases with a modified technique of selected cerebral perfusion (SCP) under deep hypothermic circulatory arrest (DHCA) during ascending aorta and total aortic arch replacement combined with transaortic stented graft implantation into the descending aorta for acute and chronic type A aortic dissection. Right auxiliary artery cannulation was routinely used for cardiopulmonary bypass (CPB) and SCP in this procedure. Generally, this technique requires two main pumps for two arterial lines before we applied the modified technique; one for CPB and the other for SCP. In order to simplify the circuit of the extracorporeal circuit (ECC) to operate easily, the arterial line was separated into two branches with a Y–connector on the operating table, one for axillary artery perfusion and the other for graft perfusion connected to the ECC set–up. This method is easy for the perfusionist to install and convenient for the surgeon. This is a safe and simple to use modified technique for SCP under DHCA during ascending aorta and total aortic arch replacement combined with transaortic stented graft implantation into the descending aorta.

The Optimal Flow Rate for Antegrade Cerebral Perfusion During Deep Hypothermic Circulatory Arrest

The aim of this study is to compare cerebral protection using antegrade cerebral perfusion (ACP) with various flow rates during deep hypothermic circulatory arrest (DHCA) in a piglet model. Twenty-three piglets were randomized to five groups: the control group (n = 3), DHCA group (n = 5), ACP25 group (n = 5), ACP50 group (n = 5), and ACP80 group (n = 5). Three control piglets did not undergo operations. Twenty piglets underwent cardiopulmonary bypass (CPB) and DHCA for 60 min at 20°C. ACP was conducted at 0, 25, 50, and 80 mL/kg/min in the DHCA, ACP25, ACP50, and ACP80 group, respectively. Serum S-100B protein and neuron-specific enolase were monitored, and brain tissues were assayed for the activities of caspase-3 and stained for the evidence of apoptotic cellular injury. Rise in serum S-100B level (post-CPB-pre-CPB) in the ACP50 group was significantly lower than that in the ACP80 group (P = 0.001). Caspase-3 levels were significantly elevated in the ACP80 group compared with the ACP25 (P = 0.041) and ACP50 group (P = 0.01), while positive terminal deoxyneucleotidyl transferase-mediated biotin-dUTP nick end labeling reaction scores in the ACP80 group were significantly higher than those in the ACP25 (P = 0.043) and ACP50 group (P = 0.023). Cerebral protection effects of ACP at 25 and 50 mL/kg/min were superior to that of ACP at 80 mL/kg/min as determined by cerebral markers, immunology, and histology.