Start Of Extracorporeal Circulation Research Articles

Direct aortic cannulation, a safe alternative to femoral artery cannulation - 17 years of type A dissection surgery experience

Aim: Optimal cannulation strategy for acute type A aortic dissection (ATAAD) surgery remains debated. Recent guidelines have advocated antegrade systemic perfusion through right axillary artery (RAX) cannulation, instead of femoral artery (FA) cannulation. However, RAX cannulation can be technically challenging and time-consuming. On the other hand, direct (ascending) aorta (DA) cannulation is a swift procedure that also ensures downstream antegrade flow. In this regard, we assessed whether DA cannulation is a safe alternative to FA cannulation. Methods: Records of all patients undergoing ATAAD surgery between 2006-2022 at the Radboud University Medical Center were retrospectively reviewed. Results: In total, 281 patients underwent surgery for ATAAD during the investigated period. Three patients were excluded due to death before the start of extracorporeal circulation and four because of RAX cannulation. Of the remaining 274 patients, 53% (N = 145) received primary FA and 47% (N = 129) DA cannulation, with a success rate of 98% for both approaches. Surgical mortality (combined in-hospital and 30-day) was 9.9% (7.8% DA group vs. 11.7% FA group, P = 0.271). New permanent neurological damage was seen in 10.9% vs. 6.9% (P = 0.248), respectively. In multivariate analysis, cannulation strategies were not significantly associated with surgical mortality nor postoperative new permanent neurological damage. Conclusion: DA cannulation offers a safe and fast alternative to FA cannulation in ATAAD surgery. There were no significant differences in mortality and neurological complications. Future studies should focus on the differences between RAX and DA cannulation strategies on postoperative outcomes in ATAAD surgery.

Effect of different cardioprotective methods on extracorporeal circulation in fetal sheep: a randomized controlled trial

BackgroundCongenital heart disease is a leading cause of death in newborns and infants. The feasibility of fetal cardiac surgery is linked to extracorporeal circulation (ECC); therefore, cardioplegic solutions need to be effective and long-lasting.MethodsEighteen pregnant sheep were divided into an ECC-only group, St. Thomas’ Hospital cardioplegic solution (STH1) group (STH group), and HTK preservation solution (Custodiol®) group (HTK group). Markers of myocardial injury including troponin I (cTnI), troponin T (cTnT) and creatine kinase myocardial band (CKMB) were measured at specific time points (T1: pre-ECC, T2: 30 min of ECC, T3: 60 min of ECC, T4: 60 min post-ECC, T5: 120 min post-ECC). Myocardial tissue was removed from the fetal sheep at T5, and apoptosis was detected by TUNEL staining.ResultsChanges in the serum cTnI, cTnT and CKMB concentrations were not significantly different among the three groups before and during the ECC(T1,T2,T3). At 60 min after ECC shutdown(T4), cTnI and cTnT concentrations were significantly higher in the STH group than before the start of ECC. The concentration of cTnI was higher in the STH group than in the HTK and ECC-only groups. The concentration of cTnT was higher in the STH group than in the ECC-only group. At 120 min after ECC shutdown(T5), cTnI and cTnT concentrations were significantly higher in the ECC and HTK groups than before the start of ECC, and CKMB concentration was significantly higher in STH and HTK groups. The concentrations of cTnT, cTnI and CKMB was higher in the STH group than in the HTK and ECC-only groups. The number of TUNEL-positive cells in the HTK and STH groups was higher than in the ECC-only group. The number of TUNEL-positive cells in the STH group was higher than in the HTK group. There was no statistically significant difference among the groups in the heart rate and mean arterial pressure after ECC.ConclusionThe HTK preservation solution was significantly better than STH1 in reducing the release of cardiomyocyte injury markers and the number of apoptotic cells in fetal sheep ECC. Fetal sheep receiving ECC-only had an advantage in all indicators, which suggests ECC-only fetal heart surgery is feasible.

First results of HeartWare left ventricular assist device implantation with tunnelling of the outflow graft through the transverse sinus.

The number of left ventricular assist device (LVAD) implants for the treatment of advanced heart failure is increasing tremendously. The main therapeutic goal of this operation is to provide a bridge to transplant for patients awaiting a donor heart. In 2011, we developed a novel, minimally invasive surgical technique for LVAD implantation. To avoid possible outflow graft injuries during redo sternotomies as well as to provide a more physiological outflow towards the aortic arch, a further modification of this approach was made with outflow graft tunnelling through the transverse sinus. More than 500 LVADs were implanted at Hannover Medical School between 2008 and 2015. From September 2012 to December 2015, we used this novel technique in 17 consecutive bridge-to-transplant patients and analysed their clinical outcomes retrospectively. Baseline characteristics were obtained for all patients, and outcome data were collected from a review of electronic medical records. Subsequently, we compared the results of a data analysis of a group of 86 patients with a minimally invasive left thoracotomy LVAD implantation with the results from patients in a control group receiving a conventional outflow graft placement between May 2009 and January 2015. Our data demonstrate that the outcomes and adverse events of the operated group were comparable to those of the control group. Three patients of the study group died within the first year (3 of 17, 18%); survival to 3 years was 84%. The adverse events were similar in both groups. The study group had 3 ischaemic strokes (18%) and 1 LVAD thrombosis (6%). Five patients had LVAD thrombosis (5 of 86, 6%) and 6 in the control group had ischaemic strokes (6 of 86, 7%). The average in-hospital stay was 35.4 days for the study group and 27.4 days for the control group. Three patients from the study group and 5 from the control group had cardiac transplants. The average time until cannulation and start of extracorporeal circulation was 56 min in the study group and 96 min in the control group. Re-thoracotomy was necessary in 2 patients from the control group, whereas none was necessary in the study group. LVAD implantation with outflow graft tunnelling through the transverse sinus is an innovative technique to prevent outflow graft damage in case of cardiac resternotomy. The results of this study show that there are no significant differences in pump speed or flow, adverse events or patient outcomes compared with the standard implant techniques. The theoretical benefits of this novel technique are the reduced risk in redo cases and the physiological direction of blood flow. Consequently, this procedure might be particularly suitable for younger patients who received an LVAD as a bridge-to-transplant option.

Ciclosporin to Protect Renal function In Cardiac Surgery (CiPRICS): a study protocol for a double-blind, randomised, placebo-controlled, proof-of-concept study

IntroductionAcute kidney injury (AKI) after cardiac surgery is common and results in increased morbidity and mortality. One possible mechanism for AKI is ischaemia–reperfusion injury caused by the extracorporeal circulation (ECC),...

Abstract 73: Changes in AMSA During Controlled Coronary Perfusion by Extracorporeal Circulation in a Swine Model of Ventricular Fibrillation

Background: Previous VF studies in rats showed that 6 min of CPR was needed before an electrical shock could be successful in reestablishing cardiac activity. During this interval the amplitude spectral area (AMSA) - a method of VF waveform analysis - progressively rose reaching a plateau within the same interval required for enabling successful defibrillation. No previous studies have examined AMSA continuously using a model of tightly controlled CPR. Methods: VF was induced and left untreated for 8 min in 16 swine after which extracorporeal circulation (ECC) was maintained for 10 min adjusting its flow to generate a coronary perfusion pressure of 10 mmHg. AMSA was calculated from the VF signal in the frequency domain within 2-48 Hz and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s. Results: AMSA progressively declined during untreated VF. During ECC, AMSA rose from 6.8±1.9 to 12.4±4.1 mV*Hz (p<0.001). The increase occurred early during ECC and plateaued after 4 to 6 minutes (Figure). Individual experiments showed distinct and varying AMSA patterns during ECC. The average peak AMSA was reached 368 ± 127 s after the start of ECC. Conclusion: The time course of AMSA varied among animals suggesting variability in the time required for the myocardium to reach the optimal conditions for successful defibrillation and highlights the value of continuous monitoring of AMSA during CPR.

Initial results of an optimized perfusion system

In order to reduce the negative effects of extracorporeal circulation (ECC), the perfusion system and management were optimized at our institution. The goals of optimization were a reduction in the priming volume, in the foreign surface area and in microbubble activity, as well as optimization of suction blood management. Sixty patients were included in this retrospective study. Patients were assigned to two groups, with regard to the use of an optimized perfusion system (OPS-group, n=30) and a standard perfusion system (SPS-group, n=30). All patients underwent elective procedures. There were no significant differences with respect to patient demographics and operation time. ECC time and cross-clamp time were significantly longer in the OPS group. Statistically significant differences in outcome between the two groups were seen with regard to the following variables: effective priming volume (OPS: 775±447ml; SPS: 1610±0ml; p<0.0001), hemoglobin drop after the start of ECC (OPS: 2.7±1.2g/dl; SPS: 4.2±0.8g/dl; p<0.0001), c-reactive protein on postoperative day 2 (OPS: 121.0±59.4 U/l; SPS: 164.0±50.2 U/l; p=0.003). With regard to the use of blood transfusions, a 33% reduction in the overall amount of transfused units was seen. The rate of patients without transfusions during the entire hospital stay increased from 37% (SPS) to 53% (OPS). The mean transfused red blood cell units per patient was lower in the OPS-group (1.6±2.4 units) than in the SPS-group (2.3±3.5 units). With the described optimized perfusion system, a significantly lower priming volume, leading to less hemodilution after the onset of CPB, was achieved. The amount of blood transfusions and the inflammatory response were reduced.

Comparing microvascular alterations during minimal extracorporeal circulation and conventional cardiopulmonary bypass in coronary artery bypass graft surgery: A prospective, randomized study

Minimal extracorporeal circulation (MECC) has been introduced in coronary artery bypass graft (CABG) surgery, offering clinical benefits owing to reduced hemodilution and no blood-air interface. Yet, the effects of MECC on the intraoperative microvascular perfusion in comparison with conventional extracorporeal circulation (CECC) have not been studied so far. The current study aimed to analyze alterations in microvascular perfusion at 4 predefined time points (T1-T4) during on-pump CABG using orthogonal polarization spectral imaging. Forty patients were randomized for being operated on with either MECC or CECC. Changes in functional capillary density (FCD), blood flow velocity, and vessel diameter were analyzed by a blinded investigator. After start of extracorporeal circulation (ECC) and aortic crossclamping (T2), both groups showed a significant drop of FCD, with a significantly higher FCD in the MECC group (206.8 ± 33.6 cm/cm² in CECC group versus 217.8 ± 35.3 cm/cm² in MECC group; P = .034). In the late phase of the ECC (T3), FCD in the MECC group was already recovered, whereas FCD in the CECC group was still significantly depressed (223.1 ± 35.6 cm/cm² in MECC group; P = .100 vs T1; 211.1 ± 36.9 cm/cm² in CECC group; P = .017 vs T1). After termination of ECC (T4), FCD recovered in both groups to baseline. Blood flow velocity tended to be higher in the MECC group, with a significant intergroup difference after aortic crossclamping (T2). Orthogonal polarization spectral imaging data reveal an impairment of microvascular perfusion during on-pump CABG. Changes in FCD indicate a faster recovery of the microvascular perfusion in MECC during the reperfusion period. Beneficial recovery of microvascular organ perfusion could partly explain the perioperative advantages reported for MECC.

Hemolysis in extracorporeal circulation: relationship between time and procedures

Extracorporeal circulation (EC) is very important in cardiac surgery but causes significant damage to the blood, including hemolysis. To quantify the rate of hemolysis at different times during EC in elective coronary artery bypass grafting. We measured rates of hemolysis of 22 patients at 6 different times during myocardial revascularization during EC: T0 - before the start of EC, T1 - five minutes after of the EC initiation, T2 - 30 minutes of EC, T3 - immediately before the aortic unclamping, T4 - immediately before passage of the residual volume to the patient and T5 - five minutes after the passage of the residual volume to the patient. Rates of hemolysis were calculated between the intervals of time: T0-T1; T1-T2; T2-T3; T3-T4 and T4-T5. The first 5 minutes after the EC showed the highest rate of hemolysis (P = 0.0003) compared to the others calculated rates, representing 29% of the total haemolysis until T4 (Immediately before passage of the residual volume to the patient). There were no significant changes in the rate of hemolysis during the suction in the aortic root (P> 0.38), nor with the procedure used for the passage of the residual volume of blood in the circuit to the patient.

Impact of deep hypothermic circulatory arrest on the BIS index

Study Objective To investigate the influence of duration of deep hypothermic circulatory arrest (DHCA) on recovery of the bispectral index (BIS). Design Prospective cohort study. Setting Operating room of university teaching hospital. Patients 30 adult, ASA physical status III and IV patients scheduled for cardiac surgery with extracorporeal circulation (ECC) and DHCA. Interventions There were no study-specific interventions undertaken with the study patients. Measurements After induction of anesthesia, propofol and sufentanil were used for maintenance. Duration until BIS values reached indices of 10, 20, and 30 after DHCA was measured. ΔBIS was defined as the difference between BIS before the start of ECC and after DHCA at the same nasopharyngeal body temperature. Data are means ± SD (ranges). Main Results Duration of DHCA was 24 ± 15 min (8-71 min). The deepest nasopharyngeal temperature was 20.1 ± 2.7°C at the end of DHCA. BIS reduction was 1.8/°C. At the end of DHCA, BIS was 2 ± 6 and at the end of ECC, BIS was 33 ± 11. Duration until BIS reached a value of 10 (BIS10) was 23 ± 21 min (0-83 min); until BIS reached 20 (BIS20): 36 ± 36 min (0-140 min); and until BIS reached 30 (BIS30): 43 ± 29 min (1-130 min). Regression analysis between duration of DHCA and BIS10 was R = 0.76; BIS20: R = 0.67; and BIS30: R = 0.54. Conclusion Deep hypothermia influences BIS linearly. In addition, there appears to be a reasonable correlation between recovery of BIS values and duration of DHCA.

Cytokine removal with a large pore cellulose triacetate filter: an ex vivo study.

To test the hypothesis that hemofiltration using a new large pore cellulose triacetate hemofilter can achieve effective ultrafiltration of cytokines. Ex-vivo study. Laboratory of Intensive Care Unit in tertiary hospital. Six healthy volunteers. Blood from 6 volunteers was incubated for 4 hours with 1 mg of endotoxin and then circulated through a closed hemofiltration circuit with a large pore cellulose triacetate hemofilter (nominal cut-off point: 60 kilodaltons). Hemofiltration was conducted at 1 L/h or 6 L/h of ultrafiltrate (UF) flow at the start of extra-corporeal circulation, and after 2 and 4 hours. Samples were taken from the arterial, venous and UF sampling ports. IL-Ibeta, IL-6, IL-8, IL-10, TNFalpha, and albumin were measured. Sieving coefficients (SC) above 0.6 were achieved for IL-Ibeta and IL-6 and SCs above 0.3 were achieved for IL-8 and TNF-alpha at 1 L/h. Sieving coefficients of all cytokines (except IL-10, p=0.22) were reduced when the ultrafiltration rate was increased from IL/h to 6 L/h (p<0.01), but the increase in ultrafiltration rate resulted in an overall increase in the clearance of all cytokines (p<0.001). The highest SC for albumin was 0.07 at 4 hours at 1 L/h, and fell to 0.01 at 6 L/h. The SCs for IL-8 fell at 4 hours (p<0.01), but the SCs for other cytokines did not change. No adsorption of cytokines and albumin was observed. High volume hemofiltration (HVHF) using a new large pore cellulose triacetate filter achieved cytokine clearances greater than those reported with currently available hemo filters.

ＭＩＣＳにおける体外循環開始時の脱血方法について

当施設では,患者に優しい低侵襲の心臓手術として小切開で開心術(MICS)を行っている。MICS時の体外循環では,細いカニューレで脱血を行うため,遠心ポンプを用いた強制脱血を行っている。遠心ポンプによる強制脱血を施行した場合,気泡混入の可能性があるため,我々は遠心ポンプの手前に密閉したハードシェル貯血槽を用いた体外循環回路を考案し,良好な脱血状態を得ることができた。右心房を開ける2本脱血の場合,体外循環開始時に気泡混入の可能性はあるが,1本脱血の場合,体外循環開始時に気泡混入の可能性は少ないので,貯血槽をバイパスし体外循環を開始する。脱血方法により体外循環の開始法を変え,特に1本脱血時には貯血槽をバイパスすることにより,PCPS回路と同様に,低充填量で容易に体外循環が開始できるようになった。

Surgical alternatives in pulmonary embolism

Summary Surgical intervention in pulmonary embolism (PE) is still associated with an overall fatal outcome of 30–60% depending on the hemodynamic condition of the patient when operated. Thus conservative treatment using heparin or fibrinolytic agents has become the treatment of choice. In grade IV PE, however, surgical treatment might be a live-saving option in cases of shock or contraindication to fibrinolysis. The objective of this study was to evaluate the results of a modified surgical approach to treat fulminant PE. From May 1993 to June 1996 12 patients with fulminant PE were operated under emergency conditions, with six patients (50%) under or after cardiopulmonary resuscitation (CPR). A modified surgical approach was performed allowing for selective thrombectomy from both pulmonary artery systems down to the segmental artery level as well as simultaneous closed venous thrombectomy with clearance of the major body veins during extracorporeal circulation (ECC). In two cases the acute form of PE was associated with unilateral, chronic and subtotal obstructing embolization requiring deep hypothermic circulatory arrest and pulmonary thrombendarterectomy. In six patients systolic pulmonary artery pressure (PAP) was measured immediately prior to start of ECC, prior to closure of the chest and after an interval of 3–6 days. It could be demonstrated that an ad hoc fall from 53.3 ± 10.8 mmHg to 29.7 ± 13.1 mmHg (P=0.007) resulted, which continued during the first postoperative days to 23.3 ± 6.5 mmHg. All but one polytraumatized patient, in whom no pulmonary embolism was found at surgery, survived (92%). One patient died after prolonged preoperative CPR 4 months after surgery due to permanent neurologic damage, another patient died 20 months after surgery due to malignancy. All other patients (follow-up range 9–45 months) are fully rehabilitated and free of PE recurrency under coumadin medication, with three patients having required the placement of a LGM caval filter for ongoing iliac vein thrombosis. Fast and accurate diagnosis of grade IV PE still is problematic in an emergency situation. However, this study concluded that the modified surgical approach with complete desobliteration of the pulmonary artery system as well as simultaneous venous thrombectomy represents a safe and highly efficient therapeutic option in grade IV PE to immediately relieve acute pulmonary artery hypertension and to prevent early embolic recurrence. Long-term freedom from re-embolization is warranted by the differentiated use of caval filters and continued anticoagulation.

Effect of Physical Protection on the Mesothelial Integrity of the Pericardium

Background. Mesothelial integrity is essential for the prevention of pericardial adhesions. This study was performed to determine the effect of physical protection of the pericardium on mesothelial integrity.Methods. A pericardial biopsy specimen was obtained at the time of pericardiotomy (0 minutes) in 10 patients undergoing a cardiac operation for the first time. The left free edge of the pericardiotomy was plicated inward to protect the mesothelium. Biopsy specimens were obtained from the protected and unprotected pericardium at 45 and 90 minutes after the start of extracorporeal circulation. Mesothelial integrity and the local inflammatory response were then assessed and graded histologically.Results. The mesothelium was found to be present in the protected specimens at 0, 45, and 90 minutes, but it was found to be denuded in the unprotected specimens (p = 0.003 at 45 minutes; p = 0.004 at 90 minutes). Local inflammation was totally established in both the protected and unprotected specimens at 45 minutes.Conclusions. Physical agents appear to be the main factor that is damaging to the pericardial mesothelium, and this is an important concept to be taken into consideration when designing a method to prevent pericardial adhesions.(Ann Thorac Surg 1997;63:1091–4)

ＭＡＰ加赤血球の心臓外科手術における使用経験

Purpose:Red blood cells added MAP as a additive solution (RC-MAP), developed by the Japanese Red Cross Society, is reported to be superior to the conventional CRC in that the good quality of red blood cells can be preserved for a long term. Another advantage is that the removal of huffy coat serves to alleviate transfusion-induced adverse reactions. We used RC-MAP (preserved 10-12 days after collection) and FFP (obtained from the same donors) in a total of 10 cases requiring cardiac surgery (3 for ASD, 1 for VSD+RSV, 1 fort AVR, 1 for MVR and 4 for AC bypass) from the start of extracorporeal circulation to postoperative management. This report describes the clinical courses in these cases.Results:The mean time of extracorporeal circulation was 112.5±71.3min. The volume of bleeding from the postoperative drain ranged from 4.6 to 20ml/kg except 35ml/kg in the AVR case, showing little difference from that in the cases of blood component and fresh whole blood transfusion. Fibrinogen and prothrombin time were within the normal ranges. Free Hb and BUN returned to the normal in a short time. Renal disturbance was not found in any case. The red blood cells of RC-MAP filled in the artificial heart-lung apparatus were lableled with Cr51. The half life proved to be about 26 days with little difference from that in the cases of fresh whole blood transfusion.The time of extracorporeal circulation was longer in one of the four AC bypass cases and the AVR case than in others. The total volume of RC-MAP used throughout the course was accordingly larger in these cases. This suggested that some appropriate measures should be taken for such cases, because hypoproteinemia and relative shortage of coagulation factors might arise from MAP-induced hyperhemodilution. With this in mind, we decreased MAP content in RC-MAP immediately before use for the cases treated after the above two cases. This measure could bring a good result.

End-Tidal Carbon Dioxide Tension as a Monitor of Native Blood Flow During Resuscitation by Extracorporeal Circulation

In a porcine model of cardiac arrest, we investigated end-tidal carbon dioxide tension as a monitor of native blood flow during resuscitation by extracorporeal circulation. After 15 minutes of cardiac arrest and after precordial compression and transthoracic countershocks had failed, extracorporeal circulation consistently restored spontaneous circulation. Native end-tidal carbon dioxide tension, which averaged 29.8 +/- 1.0 mm Hg before arrest, was only 5.2 +/- 0.8 mm Hg during precordial compression. After the start of extracorporeal circulation, native end-tidal carbon dioxide tension was measured during 15-second interruptions of pump flow. End-tidal carbon dioxide tension progressively increased with a corresponding increase in native cardiac index. The correlation coefficients between end-tidal carbon dioxide tension and native cardiac index averaged 0.92 +/- 0.03 (mean +/- standard error of the mean). When end-tidal carbon dioxide tension exceeded 15 mm Hg, mean aortic pressure in each instance was 60 mm Hg or greater, and the animal was successfully weaned from extracorporeal support. We conclude that end-tidal carbon dioxide tension serves as a reliable monitor of blood flow through the lung and therefore of native cardiac output during weaning from extracorporeal circulation. It therefore indicates when native cardiac output is likely to be adequate to sustain spontaneous circulation.

End-tidal carbon dioxide tension as a monitor of native blood flow during resuscitation by extracorporeal circulation

In a porcine model of cardiac arrest, we investigated end-tidal carbon dioxide tension as a monitor of native blood flow during resuscitation by extracorporeal circulation. After 15 minutes of cardiac arrest and after precordial compression and transthoracic countershocks had failed, extracorporeal circulation consistently restored spontaneous circulation. Native end-tidal carbon dioxide tension, which averaged 29.8 +/- 1.0 mm Hg before arrest, was only 5.2 +/- 0.8 mm Hg during precordial compression. After the start of extracorporeal circulation, native end-tidal carbon dioxide tension was measured during 15-second interruptions of pump flow. End-tidal carbon dioxide tension progressively increased with a corresponding increase in native cardiac index. The correlation coefficients between end-tidal carbon dioxide tension and native cardiac index averaged 0.92 +/- 0.03 (mean +/- standard error of the mean). When end-tidal carbon dioxide tension exceeded 15 mm Hg, mean aortic pressure in each instance was 60 mm Hg or greater, and the animal was successfully weaned from extracorporeal support. We conclude that end-tidal carbon dioxide tension serves as a reliable monitor of blood flow through the lung and therefore of native cardiac output during weaning from extracorporeal circulation. It therefore indicates when native cardiac output is likely to be adequate to sustain spontaneous circulation.

Intraocular Pressure Variations During Extracorporeal Circulation and Some Influencing Factors

Intraocular pressure (IOP) variations during extracorporeal circulation (ECC) and some influencing factors were studied prospectively in 38 patients undergoing cardiovascular surgery. IOPs were measured preoperatively, during EEC after 5 min, 10 min, and then every 15 min and on the first, second and third postoperative days. IOP, haematocrit, arterial perfusion pressure, partial O2 pressure, partial CO2 pressure, pH, and blood bicarbonate levels were measured simultaneously. After beginning ECC, arterial perfusion pressure and haematocrit values decreased suddenly while IOP was raised immediately. The sudden increase of blood volume at the start of ECC is the probable cause of IOP elevation. Afterwards IOP levels decreased to pre-ECC levels. We think that the drop is due to the effect of mannitol in the priming solution and hyposecretion of aqueous humor due to insufficient nutrition-oxygenation of the corpus ciliaris after the haemodynamics have stabilised.

Deep hypotension at the start of extracorporeal circulation during open heart surge

Deep hypotension at the start of extracorporeal circulation during open heart surge

Cerebral Dysfunction Following Extracorporeal Circulation for Aortocoronary Bypass Surgery: No Differences in Neuropsychological Outcome After Pulsatile Versus Nonpulsatile Flow

Nonpulsatile perfusion techniques with extracorporeal circulation for open-heart surgery and aortocoronary bypass grafting are widely used; this treatment is often followed by temporary or permanent neurological deficits. Experimental studies suggest that pulsatile flow may be of greater benefit because of its ability to ameliorate cerebral microcirculation. We therefore investigated 22 men who underwent aortocoronary bypass grafting. Patients were randomly divided into either a group undergoing nonpulsatile (n = 14) or pulsatile flow (n = 8). Neurological examinations were done prior to the operation and on the 7th postoperative day. EEG, cerebral blood flow (CBF), and the metabolic rates of O2 (CMR O2) and glucose (CMR Glucose) were measured before anaesthesia and 30 minutes after the start of extracorporeal circulation, when venous blood temperature was 26 degrees C. Postoperative neurological symptoms consisted of cranial nerve palsies, dysfunctions of the visual cortex, cerebellar symptoms, and slight arm paresis, but no differences between the two treatment groups were detected. Moreover, changes in EEG, CBF, and CMR rates during anaesthesia did not differ between the two groups. Our data suggest that pulsatile flow is not superior to the nonpulsatile perfusion technique, but to confirm this larger patient samples are required.

Substance P- and leu-enkephalin-immunoreactive nerves before and after myocardial ischaemia, hypothermic chemical cardioplegia and reperfusion injury during open-heart surgery

During open-heart surgery, myocardial biopsies were obtained before the start of extracorporeal circulation (from the right auricular appendage) and after weaning from the pump (from the right atrium), and processed for immunocytochemical demonstration of substance P- and leu-enkephalin-immunoreactive nerve fibres and for electron microscopy. Substance P-immunoreactive nerves were seen around blood vessels, between myocardial cells and forming large glomerulus-like loops, but were not numerous. Leu-enkephalin-immunoreactive nerves were very sparse. We therefore believe that both nerve types primarily are modulatory axons. In the post-weaning specimens, nerves of both types were more numerous (attributable to the different site of biopsy), and no change was seen in the immunofluorescence reaction. The ultrastructure (all types) of nerve terminals was well preserved, although myocardial damage was obvious in many specimens. Cardiac nerves, including peptidergic nerves, thus seem to be relatively resistant to ischaemia, hypothermic chemical cardioplegia and reperfusion injury.